Sample records for ultrasonic pulse transmission

  1. Pulsed ultrasonic stir welding system

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    An ultrasonic stir welding system includes a welding head assembly having a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. During a welding operation, ultrasonic pulses are applied to the rod as it rotates about its longitudinal axis. The ultrasonic pulses are applied in such a way that they propagate parallel to the longitudinal axis of the rod.

  2. Pulsed ultrasonic stir welding method

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.

  3. Ultrasonic flowmetering with reflected pulses

    E-print Network

    Hoyle, David C.

    1984-01-01

    A transit time type ultrasonic flowmeter was tested with two different reflected pulse trajectories in flowing air at ambient conditions against an orifice meter. The flowmeter was designed to be highly accurate, to require ...

  4. 21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...false Ultrasonic pulsed echo imaging system. 892.1560 Section...1560 Ultrasonic pulsed echo imaging system. (a) Identification. An ultrasonic pulsed echo imaging system is a device intended...measure the duration of an acoustic pulse from the...

  5. Ultrasonic thermometry using pulse techniques.

    NASA Technical Reports Server (NTRS)

    Lynnworth, L. C.; Carnevale, E. H.

    1972-01-01

    Ultrasonic pulse techniques have been developed which, when applied to inert gases, provide temperature measurements up to 8000 K. The response time can be less than 1 msec. This is a significant feature in studying shock-heated or combusting gases. Using a momentary contact coupling technique, temperature has been measured inside steel from 300 to 1500 K. Thin-wire sensors have been used above 2000 K in nuclear and industrial applications where conditions preclude the use of thermocouples, resistance devices, or optical pyrometers. At 2500 K, temperature sensitivity of 0.1% is obtained in Re wire sensors 5 cm long by timing five round trips with an electronic instrument that resolves the time interval between selected echoes to 0.1 microsec. Sensors have been operated at rotational speeds over 2000 rpm and in noisy environments. Temperature profiling of up to ten regions using only a single guided path or beam has also been accomplished.

  6. An Ultrasonic\\/Optical Pulse Sensor for Precise Distance Measurements

    Microsoft Academic Search

    Darold Wobschall; Ming Zeng; Bhooma Srinivasaraghavan

    2005-01-01

    The combined ultrasonic transit time and optical pulse method described here is an improvement over the standard ultrasonic echo by providing a lower signal loss and more precise location of sensor reference points, specifically the transmitting and receiving transducers. The ultrasonic transit time sensor described here uses only a one-way ultrasonic pulse. The transit time, typically 0.5 to 50 ms,

  7. Method and means of transmitting and receiving broad-band unipolar, ultrasonic pulses for ultrasonic inspection

    DOEpatents

    Thompson, Donald O. (Ames, IA); Hsu, David K. (Ames, IA)

    1993-12-14

    The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses.

  8. Pulse shaping with transmission lines

    DOEpatents

    Wilcox, R.B.

    1985-08-15

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  9. Pulse shaping with transmission lines

    DOEpatents

    Wilcox, Russell B. (Oakland, CA)

    1987-01-01

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  10. Pulse shaping with transmission lines

    NASA Astrophysics Data System (ADS)

    Wilcox, R. B.

    1985-08-01

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  11. Air-coupled ultrasonic transmission measurement through paper during wetting

    NASA Astrophysics Data System (ADS)

    Stor-Pellinen, Jyrki; Hæggström, Edward; Karppinen, Timo; Luukkala, Mauri

    2002-05-01

    In the first part of this work ultrasonic thickness resonances were measured with offset paper samples, 80-240 g m-2 in grammage. The resonance frequency was found to be linearly dependent on the grammage of the samples. In the second part of this investigation 240 g m-2 offset paper samples were wetted with a mist pulse of either water or isopropanol. This pulse, 61±4 ms in duration, was generated by a high-power ultrasonic actuator. The change in resonance frequency, initially 660±5 kHz, was monitored during the wetting of the paper sample. An ultrasonic burst, frequency swept from 500 to 900, 600 to 1000 and 1300 to 1700 kHz, was transmitted through the sample at a 10 Hz repetition rate. This made it possible to follow the wetting of the sample at several frequencies by the same measurement. It was also possible to follow the temporal development of the apparent absorption coefficient of the sample. The shape of the transmission curves suggests that two different processes, capillary wetting and diffusion wetting, can be distinguished.

  12. Medical tomograph system using ultrasonic transmission

    NASA Technical Reports Server (NTRS)

    Heyser, Richard C. (Inventor); Nathan, Robert (Inventor)

    1978-01-01

    Ultrasonic energy transmission in rectilinear array scanning patterns of soft tissue provides projection density values of the tissue which are recorded as a function of scanning position and angular relationship, .theta., of the subject with a fixed coordinate system. A plurality of rectilinear scan arrays in the same plane for different angular relationships .theta..sub.1 . . . .theta..sub.n thus recorded are superimposed. The superimposition of intensity values thus yields a tomographic image of an internal section of the tissue in the scanning plane.

  13. Portable apparatus with CRT display for nondestructive testing of concrete by the ultrasonic pulse method

    NASA Technical Reports Server (NTRS)

    Manta, G.; Gurau, Y.; Nica, P.; Facacaru, I.

    1974-01-01

    The development of methods for the nondestructive study of concrete structures is discussed. The nondestructive test procedure is based on the method of ultrasonic pulse transmission through the material. The measurements indicate that the elastic properties of concrete or other heterogeneous materials are a function of the rate of ultrasonic propagation. Diagrams of the test equipment are provided. Mathematical models are included to support the theoretical aspects.

  14. Ultrasonic spectrum analysis using frequency-tracked gated RF pulses

    NASA Technical Reports Server (NTRS)

    Cantrell, J. H., Jr.; Heyman, J. S.

    1980-01-01

    A new method of ultrasonic frequency analysis is introduced which employs frequency-tracked gated RF drive pulses rather than shock-excited broadband spikes to generate the ultrasonic waveform. The new technique, a variation of the sampled-continuous wave technique, eliminates problems associated with finite pulse widths of conventional methods. It is shown to yield correct ultrasonic wave velocity measurements of the sample irrespective of receiver gate width or position provided any portions of two successive echoes are gated simultaneously into the spectrum analyzer. The experimental observations are substantiated by a theoretical model based on the time-frequency domain formulation of ultrasonic frequency analysis.

  15. Inline Ultrasonic Rheometry by Pulsed Doppler

    SciTech Connect

    Pfund, David M.; Greenwood, Margaret S.; Bamberger, Judith A.; Pappas, Richard A.

    2006-12-22

    This will be a discussion of the non-invasive determination of the viscosity of a non-Newtonian fluid in laminar pipe flow over the range of shear rates present in the pipe. The procedure used requires knowledge of the flow profile in and the pressure drop along a long straight run of pipe. The profile is determined by using a pulsed ultrasonic Doppler velocimeter. This approach is ideal for making non-invasive, real-time measurements for monitoring and control. Rheograms of a shear thinning, thixotropic gel will be presented. The operating parameters and limitations of the Doppler-based instrument will be discussed. The most significant limitation is velocity gradient broadening of the Doppler spectra near the walls of the pipe. This limitation can be significant for strongly shear thinning fluids (depending also on the ratio of beam to pipe diameter and the transducer's insertion angle).

  16. High current pulse transmission cable

    SciTech Connect

    Parsons, W.M.

    1990-09-28

    This invention is comprised of a transmission cable for carrying high current pulses in which an even numbered plurality of electrical conductors surrounds a central ground conductor. Each electrical conductor is connected so that it at any instant in time it will carry current of opposite polarity to the polarity carried by adjacent conductors. This arrangement cancels practically all of the external fields generated by current in the conductors.

  17. Power and Information Transmission to Implanted Medical Device Using Ultrasonic

    Microsoft Academic Search

    Hideyuki Kawanabe; Tamotsu Katane; Hideo Saotome; Osami Saito; Kazuhito Kobayashi

    2001-01-01

    Using ultrasonic, we propose here a novel method of transmitting power and information to implanted medical equipment. The proposed system is composed of two piezo oscillators and has the following functions: transmission of power and control information to an implanted device, and transmission of the information acquired by an implanted device to the outside of a living body. With amplitude

  18. Using piezoelectric sensors for ultrasonic pulse velocity measurements in concrete

    NASA Astrophysics Data System (ADS)

    Kee, Seong-Hoon; Zhu, Jinying

    2013-11-01

    The ultrasonic pulse velocity (UPV) test has been a widely used non-destructive testing method for concrete structures. However, the conventional UPV test has limitations in consistency of results and applicability in hard-to-access regions of structures. The authors explore the feasibility of embedded piezoelectric (PZT) sensors for ultrasonic measurements in concrete structures. Two PZT sensors were embedded in a reinforced concrete specimen. One sensor worked as an actuator driven by an ultrasonic pulse-receiver, and another sensor worked as a receiver. A series of ultrasonic tests were conducted to investigate the performance of the embedded sensors in crack-free concrete and concrete specimens having a surface-breaking crack under various external loadings. Signals measured by the embedded sensors show a broad bandwidth with a centre frequency around 80 kHz, and very good coherence in the frequency range from 30 to 180 kHz. Furthermore, experimental variability in ultrasonic pulse velocity and attenuation is substantially reduced compared to previously reported values from conventional UPV equipment. Findings from this study demonstrate that the embedded sensors have great potential as a low-cost solution for ultrasonic transducers for health monitoring of concrete in structures.

  19. Input Pulse Response in Nonlinear Transmission Line

    Microsoft Academic Search

    Ian M. Rittersdorf; David M. French; Michael Johnson; Y. Y. Lau; Ronald M. Gilgenbach; Donald Shiffler; Brad Hoff; John Luginsland

    2010-01-01

    Nonlinear transmission lines have been demonstrated to be an effective technique for generating high power ultrawideband or mesoband radiation without the need for a vacuum system, electron beam, or magnet. Experiments have been performed at UM on a discrete element nonlinear transmission line that uses ferrite inductors as the nonlinear element. Pulse sharpening of multi-kA input pulses has been observed

  20. Implementation of a novel pulsed ultrasonic Doppler velocity profiler

    NASA Astrophysics Data System (ADS)

    Luo, Shounan; Liu, Yan; Feng, Guanping

    2003-09-01

    The objective of the work is to apply advanced digital signal processing (DSP) and pulsed Doppler echography techniques to analyze velocity profile of the measured fluid in a closed full-pipe. In order to reliably measure velocity profile where non-intrusive ultrasonic Doppler velocity profilers (UDVPs) cannot properly transmit and receive ultrasonic signals, a single-crystal transducer was inserted directly into the fluid stream. Then ultrasonic signals were transmitted and received based on the pulsed Doppler echography theory. A modified covariance (MCOV) estimator and a TMS320VC5410 DSP chip with a high-speed up to 160 MIPS were employed to analyze spectrum of the software-gated echo signals. Finally, computer simulations were also presented to demonstrate effectiveness of the novel UDVP. Results indicate that this instrument is particularly effective in terms of velocity profiling and can be widely applied for flow measurement and fluid dynamics research.

  1. Direct scanning tunneling microscope detection of laser induced ultrasonic pulses with nanometer resolution

    Microsoft Academic Search

    J. Jersch; F. Demming; I. Fedotov; K. Dickmann

    1999-01-01

    We show the use of scanning tunneling microscope (STM) with a self-designed wide-bandwidth current preamplifier (50 MHz) for direct registration of ultrasonic pulses induced by nanosecond laser pulses in substrate. The changes in tip-sample separation caused by ultrasonic vibrations are seen as perturbations in tunneling current. At moderate incident laser pulse energy of 1-2 mJ ultrasonic waves in glass rod

  2. PROline - Ultrasonic Testing for Electron Beam and Laser Weld Seams of Transmission Control Gears - Many more Applications in Production

    Microsoft Academic Search

    Goeran VOGT; Carsten KOEHLER

    2008-01-01

    The ultrasonic testing with pulse echo method has been approved since many years as a user suitable and expressive non-destructive te sting method for electron beam- and laser weld seams. The PROline-S system is used e.g. for the inspection especially at transmission control gears for the auto motive industry in Europe. In the process of immersion technique the ultrasound will

  3. Ultrasonic pulsed phase locked loop interferometer for bolt load measurements

    NASA Astrophysics Data System (ADS)

    Allison, S. G.; Clendenin, C. G.

    The pulsed phase-locked-loop bolt monitor (P2L2) that uses ultrasonic waves to measure bolt preload with accuracies ranging from 1 to 3 percent (depending on the specific bolt) is described. To remeasure bolt load after installation, a thermal calibration factor compensates for bolt temperature changes, and a standard reference block allows correction for acoustic phase errors due to measurement equipment configuration such as utilization of a different transducer, couplant, or cable. Some examples of critical applications including Space Shuttle landing-gear wheels and NASA wind-tunnel fan blades are discussed.

  4. Ultrasonic pulsed phase locked loop interferometer for bolt load measurements

    NASA Technical Reports Server (NTRS)

    Allison, S. G.; Clendenin, C. G.

    1989-01-01

    The pulsed phase-locked-loop bolt monitor (P2L2) that uses ultrasonic waves to measure bolt preload with accuracies ranging from 1 to 3 percent (depending on the specific bolt) is described. To remeasure bolt load after installation, a thermal calibration factor compensates for bolt temperature changes, and a standard reference block allows correction for acoustic phase errors due to measurement equipment configuration such as utilization of a different transducer, couplant, or cable. Some examples of critical applications including Space Shuttle landing-gear wheels and NASA wind-tunnel fan blades are discussed.

  5. The maturity characterization of orange fruit by using high frequency ultrasonic echo pulse method

    E-print Network

    Boyer, Edmond

    The maturity characterization of orange fruit by using high frequency ultrasonic echo pulse method of the maturity of orange fruit by the ultrasonic echo pulse method with immersion in water. This study relates of maturity of the fruit without passing by penetrometric and biochemical measurements which are mostly

  6. Experimental study of underwater transmission characteristics of high-frequency 30 MHz polyurea ultrasonic transducer.

    PubMed

    Nakazawa, Marie; Aoyagi, Takahiro; Tabaru, Masaya; Nakamura, Kentaro; Ueha, Sadayuki

    2014-02-01

    In this paper, we present the transmission characteristics of a polyurea ultrasonic transducer operating in water. In this study, we used a polyurea transducer with fundamental resonance at approximately 30 MHz. Firstly, acoustic pressure radiated from the transducer was measured using a hydrophone, which has a diameter of 0.2 mm. The transmission characteristics such as relative bandwidth, pulse width, and acoustic sensitivity were calculated from the experimental results. The results of the experiment showed a relative bandwidth of 50% and a pulse width of 0.061 ?s. The acoustic sensitivity was 0.60 kPa/V with good linearity, where the correlation coefficient R in the fitting calculation was 0.996. A maximum pressure of 13.1 kPa was observed when the transducer was excited at a zero-to-peak voltage of 21 V. Moreover, we experimentally verified the results. The results of the pulse/echo experiment showed that the estimated diameters of the copper wires were 458 and 726 ?m, where the differences between the actual and measured values were 15% and 4%, respectively. Acoustic streaming was also observed so that a particle velocity map was estimated by particle image velocimetry (PIV). The sound pressure calculated from the particle velocity obtained by PIV showed good agreement with the acoustic pressure measured using the hydrophone, where the differences between the calculated and measured values were 12-19%. PMID:24035608

  7. Air-coupled ultrasonic through-transmission thickness measurements of steel plates.

    PubMed

    Waag, Grunde; Hoff, Lars; Norli, Petter

    2015-02-01

    Non-destructive ultrasonic testing of steel structures provide valuable information in e.g. inspection of pipes, ships and offshore structures. In many practical applications, contact measurements are cumbersome or not possible, and air-coupled ultrasound can provide a solution. This paper presents air-coupled ultrasonic through-transmission measurements on a steel plate with thicknesses 10.15 mm; 10.0 mm; 9.8 mm. Ultrasound pulses were transmitted from a piezoelectric transducer at normal incidence, through the steel plate, and were received at the opposite side. The S1, A2 and A3 modes of the plate are excited, with resonance frequencies that depend on the material properties and the thickness of the plate. The results show that the resonances could be clearly identified after transmission through the steel plate, and that the frequencies of the resonances could be used to distinguish between the three plate thicknesses. The S1-mode resonance was observed to be shifted 10% down compared to a simple plane wave half-wave resonance model, while the A2 and S2 modes were found approximately at the corresponding plane-wave resonance frequencies. A model based on the angular spectrum method was used to predict the response of the through-transmission setup. This model included the finite aperture of the transmitter and receiver, and compressional and shear waves in the solid. The model predicts the frequencies of the observed modes of the plate to within 1%, including the down-shift of the S1-mode. PMID:25257299

  8. Estimation of diffraction effect in ultrasonic attenuation by through-transmission substitution technique.

    PubMed

    Xing, Guangzhen; Yang, Ping; He, Longbiao

    2013-04-01

    Measurement of ultrasonic attenuation is important in clinical and industrial applications. The overall goal of this research was to characterize the diffraction effect in ultrasonic attenuation. We have followed a systematic approach, beginning with the theoretical analysis of the calculation method using the transfer function of the signal spectrum, moving on to numerical computations and experimental confirmation. The relation of sample thickness to pulse duration is presented and the transmission coefficient of the sample for different propagation modes is discussed. Particular attention is paid to the diffraction effect which is easy to be neglected but a potential source of artifacts. Numerical computations demonstrated that lower frequencies, shorter transducer distances and larger velocity difference can result in significant diffraction effect. Due to the complexity of determining interface loss in Single Sample Substitution Method (SSM), Two Samples Substitution Method (TSM) was proposed to avoid this drawback. Comparison experiment with SSM illustrates that the proposed diffraction correction model is sound in theory and feasible in practice. PMID:23290825

  9. Laser ultrasonic analysis of normal modes generated by a voltage pulse on an AT quartz sensor

    Microsoft Academic Search

    Jozefien Goossens; Loïc Martinez; Christ Glorieux; Nicolas Wilkie-Chancellier; Chighali Ould Ehssein; Stéphane Serfaty

    2006-01-01

    Laser ultrasonic detection is a versatile and highly sensitive tool for the observation of surface waves. In the following study, laser ultrasonic detection is used for the experimental study of spurious normal vibration modes of a disk quartz sensor excited by a voltage pulse. The AT cut crystal (cut of the crystal relative to the the main crystallographic axis is

  10. Ultrasonic underwater transmission of composite turbine blade structural health

    NASA Astrophysics Data System (ADS)

    Heckman, A.; Rovey, J. L.; Chandrashekhara, K.; Watkins, S. E.; Mishra, R.; Stutts, D.

    2012-04-01

    A health monitoring approach is investigated for hydrokinetic turbine blade applications. In-service monitoring is critical due to the difficult environment for blade inspection and the cost of inspection downtime. Composite blade designs provide a medium for embedding sensors into the blades for in-situ health monitoring. The major challenge with in-situ health monitoring is transmission of sensor signals from the remote rotating reference frame of the blade to the system monitoring station. In the presented work, a novel system for relaying in-situ blade health measurements is described and demonstrated. An ultrasonic communication system is used to transmit health data underwater from the rotating frame of the blade to a fixed relay station. Data are then broadcast via radio waves to a remote monitoring station. Results indicate that the assembled system can transmit simulated sensor data with an accuracy of +/-5% at a max sampling rate of 500 samples/sec. A power investigation of the transmitter within the blade shows that continuous max-sampling operation is only possible for short durations (~days), and is limited due to the capacity of the battery power source. For a 1000 mA-hr battery to last two years, the transmitter must be operated with a duty cycle of 368, which means data are acquired and transmitted every 59 seconds. Finally, because the data transmission system is flexible, being able to operate at high sample rate for short durations and lower sample rate/high duty cycle for long durations, it is well-suited for short-term prototype and environmental testing, as well as long-term commercially-deployed hydrokinetic machines.

  11. Chirp signal matching and signal power optimization in pulse-echo mode ultrasonic nondestructive testing

    Microsoft Academic Search

    Martin Pollakowski; Helmut Ermert

    1994-01-01

    Chirp pulse compression is a signal correlation technique that uses frequency modulated pulses as transmitted signals. Usually, signals with linear frequency modulation are applied. They can be generated rather easily, but their spectra are not totally matched to the transfer function of ultrasonic systems. In pulse-echo mode operation, with signal duration and consequently the time-bandwidth product being critical parameters, waveforms

  12. Characterization of Nonlinear Transmission Lines for Short Pulse Amplification

    Microsoft Academic Search

    Koichi Narahara

    2010-01-01

    Pulse propagation on nonlinear transmission lines (NLTLs), which are transmission lines with regularly spaced Schottky varactors,\\u000a is investigated for the amplification of short pulses. We recently found that the soliton developed in an NLTL experiences\\u000a an exponential amplitude growth, when it couples with an existing voltage edge. This paper clarifies how the pulse gain depends\\u000a on the device parameters, including

  13. Linear synthetic aperture modes for ultrasonic pulse-echo imaging.

    PubMed

    Lang, M; Ermert, H

    1997-05-01

    A unified approach is developed to characterize and compare the most widely used two-dimensional ultrasound pulse-echo imaging procedures. The methods of monostatic, bistatic and multistatic time-domain holography are theoretically investigated with regard to line spread functions, resolution capabilities, and the effects of multiple scattering and object inhomogeneities. Analytical derivations and computer simulations show the superiority of monostatic holography in applications such as nondestructive testing, where in most cases the assumptions generally made in the calculation of the inverse scattering formulae are justified. However, if higher order scattering and/or the spatial variations of the sound speed play a significant role, then multistatic imaging is more advantageous. A modification of this latter mode, with fixed focus on transmission, is commonly used in medical imaging B-scan systems, but implementation of the full algorithm would offer improved resolving power and reduced side lobe levels throughout the image plane. PMID:9206320

  14. Enhanced multiple ultrasonic shear reflection method for the determination of high frequency viscoelastic properties

    E-print Network

    Boyer, Edmond

    (ultrasonic pulse transmission technique, thickness shear mode, Bulk acoustic wave, ultrasonic shear wave 17 February 2010 Keywords: Viscoelasticity Multiple ultrasonic shear wave reflection method Acoustic are using delay lines in glass or quartz and normal or obli- que incidence of ultrasonic rays. The oblique

  15. Gas ultrasonic flow rate measurement through genetic-ant colony optimization based on the ultrasonic pulse received signal model

    NASA Astrophysics Data System (ADS)

    Hou, Huirang; Zheng, Dandan; Nie, Laixiao

    2015-04-01

    For gas ultrasonic flowmeters, the signals received by ultrasonic sensors are susceptible to noise interference. If signals are mingled with noise, a large error in flow measurement can be caused by triggering mistakenly using the traditional double-threshold method. To solve this problem, genetic-ant colony optimization (GACO) based on the ultrasonic pulse received signal model is proposed. Furthermore, in consideration of the real-time performance of the flow measurement system, the improvement of processing only the first three cycles of the received signals rather than the whole signal is proposed. Simulation results show that the GACO algorithm has the best estimation accuracy and ant-noise ability compared with the genetic algorithm, ant colony optimization, double-threshold and enveloped zero-crossing. Local convergence doesn’t appear with the GACO algorithm until –10?dB. For the GACO algorithm, the converging accuracy and converging speed and the amount of computation are further improved when using the first three cycles (called GACO-3cycles). Experimental results involving actual received signals show that the accuracy of single-gas ultrasonic flow rate measurement can reach 0.5% with GACO-3?cycles, which is better than with the double-threshold method.

  16. Pulsed power transmission line transformer based on modern cable technology

    Microsoft Academic Search

    Adam Lindblom; Patrik Appelgren; Anders Larsson; Sten E Nyholm; Jan Isberg; Hans Bernhoff

    2003-01-01

    A high-voltage transmission-line pulse transformer has been constructed based on modern cable technology. The transformer has been successfully tested for output powers of 0.5 GW. The high-voltage cable is equipped with a resistive layer (semicon) on the inner conductor and on the inside of the outer conductor. Semicon cables are commonly used in high-voltage transmission of electrical power. The pulse

  17. Frequency tracked gated pulse technique for ultrasonic frequency

    NASA Technical Reports Server (NTRS)

    Cantrell, Jr., John H. (Inventor); Heyman, Joseph S. (Inventor)

    1983-01-01

    A tracking generator 21 is slaved to a spectrum analyzer 23 to produce an input signal having a frequency that follows the frequency of the spectrum analyzer sweeping local oscillator 22. The input signal is gated to a transducer 26 by a transmitter gate 25 to produce ultrasonic waves in the sample 28. The resulting ultrasonic echoes are converted into electrical signals by the transducer and then gated into the spectrum analyzer by receiver gate 29. This arrangement produces spectra that are equivalent to shock-exciting the transducer with a true delta function shock-excitation.

  18. Transmission line pulse transformers—Theory and applications

    Microsoft Academic Search

    RICHARD E. MATICK

    1968-01-01

    The advent of fast rise-time pulse techniques and their increasing importance brought on by high-speed microminiature circuits and the computer industry has resulted in an increased demand for pulse transformers of various types. The basic idea of constructing transmission line type transformers has been known and used for a number of years. However, such devices have not gained widespread usage,

  19. Compressive strength evaluation of structural lightweight concrete by non-destructive ultrasonic pulse velocity method.

    PubMed

    Bogas, J Alexandre; Gomes, M Glória; Gomes, Augusto

    2013-07-01

    In this paper the compressive strength of a wide range of structural lightweight aggregate concrete mixes is evaluated by the non-destructive ultrasonic pulse velocity method. This study involves about 84 different compositions tested between 3 and 180 days for compressive strengths ranging from about 30 to 80 MPa. The influence of several factors on the relation between the ultrasonic pulse velocity and compressive strength is examined. These factors include the cement type and content, amount of water, type of admixture, initial wetting conditions, type and volume of aggregate and the partial replacement of normal weight coarse and fine aggregates by lightweight aggregates. It is found that lightweight and normal weight concretes are affected differently by mix design parameters. In addition, the prediction of the concrete's compressive strength by means of the non-destructive ultrasonic pulse velocity test is studied. Based on the dependence of the ultrasonic pulse velocity on the density and elasticity of concrete, a simplified expression is proposed to estimate the compressive strength, regardless the type of concrete and its composition. More than 200 results for different types of aggregates and concrete compositions were analyzed and high correlation coefficients were obtained. PMID:23351273

  20. Determination of thermal shock resistance in refractory materials by ultrasonic pulse velocity measurement

    Microsoft Academic Search

    D. N. Boccaccini; M. Romagnoli; E. Kamseu; Paolo Veronesi; C. Leonelli; G. C. Pellacani

    2007-01-01

    Thermal shock resistance of refractory materials is one of the most important parameters in refractory material characterization since it determines their performance in many applications. Ultrasonic pulse velocity testing was used for non-destructive quantification of thermal shock damage in refractory plates used as support for the firing of porcelain articles. When refractory materials are subjected to the industrial thermal cycles

  1. Fiber Transmission Characteristics of Parabolic Pulses Generated by Optical Pulse Synthesizer

    NASA Astrophysics Data System (ADS)

    Kashiwagi, Ken; Ishizu, Hiroyuki; Kurokawa, Takashi

    2011-09-01

    We generated parabolic pulses by using an optical pulse synthesizer and investigated their fiber transmission characteristics in detail. The generated pulses had a rms difference of less than 0.03 between the target pulse shapes and their shapes. We transmitted them through standard single-mode fibers and dispersion-shifted fibers to evaluate the influences of their dispersions and nonlinearities on the pulse shapes. We compared the experimental results with simulated results calculated by the split-step Fourier method. The two results were well matched with each other. In the high power regime, the pulses experienced the higher order nonlinearities and were strongly distorted.

  2. Local SAR in parallel transmission pulse design

    E-print Network

    Lee, Joonsung

    The management of local and global power deposition in human subjects (specific absorption rate, SAR) is a fundamental constraint to the application of parallel transmission (pTx) systems. Even though the pTx and single ...

  3. Ultrasonic Pulse Waves Propagating through Cancellous Bone Phantoms with Aligned Pore Spaces

    NASA Astrophysics Data System (ADS)

    Hosokawa, Atsushi

    2006-05-01

    To elucidate the propagation phenomena of ultrasonic waves in cancellous bone related to trabecular structure, pulse waves propagating through three cancellous bone phantoms with different skeletal frames have been experimentally observed using a water-immersion ultrasonic technique. Skeletal frames with regularly aligned pore spaces were formed to imitate the orthotropic trabecular structure, using wire gauzes, punched plates and honeycomb ceramics. The propagations of the fast and slow waves, which were clearly observed in the direction of the trabecular alignment of cancellous bone, were investigated with the frame’s structures of these phantoms.

  4. Propagation effects for electromagnetic pulse transmission

    Microsoft Academic Search

    J. R. Wait

    1986-01-01

    Past research on the propagation of EM pulse signals over the surface of the earth is reviewed, with emphasis on analytical methods to predict waveforms. The overview begins with a flat-earth model that has the virtue of simplicity particularly when displacement currents in the earth are relatively small compared with the conduction currents. Here it is seen that the rise

  5. Optimisation of pulsed ultrasonic and microwave-assisted extraction for curcuminoids by response surface methodology and kinetic study.

    PubMed

    Li, Ming; Ngadi, Michael O; Ma, Ying

    2014-12-15

    A response surface methodology and a kinetic study were used to optimise the pulsed ultrasonic and microwave techniques in the extraction of curcuminoids. Microwave-assisted extraction had the same efficiency as pulsed ultrasonic-assisted extraction, and both methods were better than continuous ultrasonic extraction of curcuminoids. For the pulsed ultrasonic-assisted extraction, the optimal conditions were 60% amplitude (AMP), 83% ethanol (v/v), 3/1 (s/s) pulsed duration/interval time and 10 min irradiation time. For the microwave-assisted extraction, the optimal conditions were 82% ethanol, 10% power level and 7 min of extraction time. Both methods used a 1:200 mass to solvent ratio. PMID:25038645

  6. Precision pulse-timing instrumentation for ultrasonic nondestructive testing

    SciTech Connect

    Duncan, M.G.

    1990-08-31

    A new, pulse-timing discriminator and B-scan time-to-pulse-height converter have been developed for the inspection of production parts. The discriminator is easy to operate and features automatic echo gating and automatic pulse polarity discrimination. This instrument combines the noise-blanking advantages of threshold discrimination with the echo-timing precision of zero-crossing discrimination to improve measurement accuracy by a factor of two over the best precious techniques. When used with the discriminator, the B-scan unit allows detection of flaws at depths less than one-fourth those obtainable with commercially available instruments. 3 refs., 20 figs., 2 tabs.

  7. Elastic moduli of precompressed pyrophyllite used in ultrahigh pressure research. [propagation of ultrasonic pulses

    NASA Technical Reports Server (NTRS)

    Sachse, W.; Ruoff, A. L.

    1974-01-01

    The propagation of ultrasonic pulses in pyrophyllite specimens was studied to determine the effect of specimen precompression on the measured elastic moduli. Measurements were made at room pressure and, for the precompressed specimens, to pressures of 3 kbar. Pyrophyllite was found to be elastically anisotropic, apparently the result of the fabric present in our material. The room pressure adiabatic bulk modulus as measured on specimens made of isostatically compacted powered pyrophyllite was determined to be 96.1 kbar. The wave speeds of ultrasonic pulses in pyrophyllite were found to decrease with increasing specimen precompression. A limiting value of precompression was found, above which no further decrease in wave speed was observed. For the shear wave speeds this occurs at 10 kbar while for the longitudinal wave at 25 kbar. In the limit, the shear waves propagate 20% slower than in the unprecompressed samples; for the longitudinal wave the difference is 30%.

  8. Generation of Subgigawatt RF Pulses in Nonlinear Transmission Lines

    Microsoft Academic Search

    Vladislav V. Rostov; Nikolai M. Bykov; Dmitry N. Bykov; Alexei I. Klimov; Oleg B. Kovalchuk; Ilya V. Romanchenko

    2010-01-01

    This paper presents the experimental results on the generation of subgigawatt radio frequency (RF) pulses using two types of nonlinear transmission lines (NLTLs). In the high-voltage coaxial lines, we used the following: 1) a periodic gas gap structure and 2) uniformly loaded saturated ferrite with axial bias. The concept of the first line is based on the in-phase composition of

  9. Corrections to complex ray tracing for modeling ultrasonic beam interaction with single interfaces when the reflection\\/transmission coefficient vanishes

    Microsoft Academic Search

    Smaine Zeroug

    2000-01-01

    A high-frequency high-order asymptotic solution is presented to model the interaction of time-harmonic ultrasonic beams with single planar interfaces. The zeroth-order term of the asymptotic expansion yields the well-known ray acoustics solution often used as the basis, for instance, of fast ultrasonic modeling and simulation codes. Whenever the interface reflection or transmission coefficient vanishes in the neighborhood of the specular

  10. Pulse compression in a time variant system with application to ultrasonic vibrometry.

    PubMed

    Martin, J S; Rogers, P H; Gray, M D

    2013-03-01

    Pulse compression is normally applied only to time-invariant systems, as the variation of a system's properties during its interrogation violates assumptions of the compression process. However, there is an exact solution to the pulse-compression problem when the time variance satisfies two criteria, which are the same as those required for the operation of an ultrasonic vibrometer in the context of a tissue elastography system. One is that the variations be very small in comparison with the wavelength of the interrogating ultrasound. The other is that the bandwidth of the variations be within one Nyquist band as sampled by the periodic interrogation signal. The solution to this problem involves a step-wise interpolation of the static pulse-compression transfer function in the frequency domain. This technique, in conjunction with the selection of an appropriate interrogation signal, offers significant advantages in measurement time or measurement resolution for an ultrasonic vibrometer limited by additive noise at the receiver. The characteristics of optimal interrogation signals for this technique are the signal's crest factor, spectral energy distribution, and phasing. These relate to the intended compression pulse, the noise, and the static response of the system. The technique has been demonstrated analytically, experimentally, and with numerical models. PMID:23464021

  11. Plasma absorption evidence via chirped pulse spectral transmission measurements

    NASA Astrophysics Data System (ADS)

    Jedrkiewicz, Ottavia; Minardi, Stefano; Couairon, Arnaud; Jukna, Vytautas; Selva, Marco; Di Trapani, Paolo

    2015-06-01

    This work aims at highlighting the plasma generation dynamics and absorption when a Bessel beam propagates in glass. We developed a simple diagnostics allowing us to retrieve clear indications of the formation of the plasma in the material, thanks to transmission measurements in the angular and wavelength domains. This technique featured by the use of a single chirped pulse having the role of pump and probe simultaneously leads to results showing the plasma nonlinear absorption effect on the trailing part of the pulse, thanks to the spectral-temporal correspondence in the measured signal, which is also confirmed by numerical simulations.

  12. An MMIC Pulse Generator Using Dual Nonlinear Transmission Lines

    Microsoft Academic Search

    Mark Kintis; Xing Lan; Flavia Fong; Donald Sawdai; Kwok Loi; Keith Kono; Augusto Gutierrez

    2007-01-01

    We present a novel nonlinear transmission line (NLTL) pulse generator using dual-NLTL, true-time-delay, waveform-alignment technique, realized in Gallium Arsenide (GaAs) monolithic microwave integrated circuit (MMIC) technology. The diodes in these two NLTLs have opposite polarities in layout. Therefore, they are responsible for sharpening the two signals' rising and falling edges separately. A simple, low-cost, wideband combiner is adopted to combine

  13. Correlation of Human Metal Model and Transmission Line Pulsing Testing

    Microsoft Academic Search

    Slavica Malobabic; Javier A. Salcedo; Alan W. Righter; Jean-Jacques Hajjar; Juin J. Liou

    2011-01-01

    Passing voltage levels measured from the human metal model tester are correlated with the failure current levels ob- tained from the transmission line pulsing (TLP) tester for electro- static discharge protection devices fabricated in 0.18- and 0.35-?m MOS technologies. Various relevant TLP parameters, including the holding voltage and ON-state resistance, are accounted for in the improved correlation formula developed in

  14. Ultrasonic ranging and data telemetry system

    DOEpatents

    Brashear, Hugh R. (Farragut, TN); Blair, Michael S. (Knoxville, TN); Phelps, James E. (Knoxville, TN); Bauer, Martin L. (Oak Ridge, TN); Nowlin, Charles H. (Oak Ridge, TN)

    1990-01-01

    An ultrasonic ranging and data telemetry system determines a surveyor's position and automatically links it with other simultaneously taken survey data. An ultrasonic and radio frequency (rf) transmitter are carried by the surveyor in a backpack. The surveyor's position is determined by calculations that use the measured transmission times of an airborne ultrasonic pulse transmitted from the backpack to two or more prepositioned ultrasonic transceivers. Once a second, rf communications are used both to synchronize the ultrasonic pulse transmission-time measurements and to transmit other simultaneously taken survey data. The rf communications are interpreted by a portable receiver and microcomputer which are brought to the property site. A video display attached to the computer provides real-time visual monitoring of the survey progress and site coverage.

  15. FDTD Simulation of Nonlinear Ultrasonic Pulse Propagation in ESWL Using Equations Including Lagrangian

    NASA Astrophysics Data System (ADS)

    Fukuhara, Keisuke; Morita, Nagayoshi

    New FDTD algorithm is proposed for analyzing ultrasonic pulse propagation in the human body, the problem being connected with ESWL (Extracorporeal Shock Wave Lithotripsy). In this method, we do not use plane wave approximation but employ directly the original equations taking account of Lagrangian to derive new FDTD algorithms. This method is applied to an experimental setup and its numerical model that resemble actual treatment situation to compare sound pressure distributions obtained numerically with those obtained experimentally. It is shown that the present method gives clearly better results than the earlier method, in the viewpoint of numerical reappearance of strongly nonlinear waveform.

  16. Exploring diffusion of ultrasonically consolidated aluminum and copper films through scanning and transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Sietins, Jennifer Mueller

    Ultrasonic consolidation (UC) is a promising manufacturing method for metal matrix composite pre-preg tapes or foils that utilizes a layer build-up technique. The process involves three main variables: applied load, oscillation amplitude, and rolling speed. A main advantage of this process is the ability to manufacture multi-material parts at lower processing temperatures compared to other metal matrix composites processes. A major disadvantage, however, is a lack of understanding of diffusion during the ultrasonic consolidation process, which is expected to affect the microstructure, bond quality, and strength within the interface region. The role of diffusion during the low temperature, short duration ultrasonic consolidation process was explored. First, scanning electron microscopy (SEM) x-ray energy dispersive spectroscopy (XEDS) was used to measure concentration profiles of ultrasonically consolidated high purity aluminum and copper through which the interdiffusion coefficients were calculated. It was found that the experimental accelerating voltage had a significant impact on the measurement of the concentration profiles, and associated interdiffusion coefficients, due to the interaction volume interference. The effect of the interaction volume on the concentration profiles was confirmed through Monte Carlo simulations of electron trajectories, and the error due the interaction volume was quantified. The results showed the diffusion distance was too small for accurate measurements with SEM XEDS even at low accelerating voltages. To significantly reduce the error due to the interaction volume, transmission electron microscopy (TEM) samples were prepared using a focused ion beam (FIB) to ensure a uniform thickness. The TEM XEDS concentration profile and images revealed intermetallic phase transformations that occurred during the welding process. TEM images also showed dislocation pile-up located at the subgrain/bulk aluminum interface. This microstructural feature supports continuous dynamic recrystallization of grains through the rearrangement of dislocations. The apparent interdiffusion coefficient closely matched the bulk diffusion concentration profile for the times and temperatures of the ultrasonically consolidated sample. Support for bulk diffusion was independently found through calculating the minimum critical temperature for bulk diffusion dominance over grain boundary diffusion for the grain sizes measured.

  17. Numerical Analysis of Narrow Band Ultrasonic Wave Generation with High Repetition Pulse Laser and Laser Scanning

    NASA Astrophysics Data System (ADS)

    Hayashi, T.; Yamaguchi, K.; Biwa, S.

    2014-06-01

    Although the easiest way to enhance ultrasonic energy generated with pulse laser is to increase laser output, excessive laser output causes damage of the surface. This study introduced an alternative way to generate burst signals without any damages at the surface using a newly developed high repetition pulse laser controlled by galvano mirrors. The calculation results using two-dimensional elastodynamic finite integration technique coupled with thermoelastic effect proved that burst wave of 1 MHz and its higher harmonics were generated while supressing excessive temperature rise using this technique. Moreover, significantly large displacements at the frequency range sufficiently lower than laser repetition rate were observed of the same order of displacements generated with one single shot with the same input energy.

  18. Waveguide piezoelectric micromachined ultrasonic transducer array for short-range pulse-echo imaging

    NASA Astrophysics Data System (ADS)

    Lu, Y.; Tang, H.; Wang, Q.; Fung, S.; Tsai, J. M.; Daneman, M.; Boser, B. E.; Horsley, D. A.

    2015-05-01

    This paper presents an 8 × 24 element, 100 ?m-pitch, 20 MHz ultrasound imager based on a piezoelectric micromachined ultrasonic transducer (PMUT) array having integrated acoustic waveguides. The 70 ?m diameter, 220 ?m long waveguides function both to direct acoustic waves and to confine acoustic energy, and also to provide mechanical protection for the PMUT array used for surface-imaging applications such as an ultrasonic fingerprint sensor. The imager consists of a PMUT array bonded with a CMOS ASIC using wafer-level conductive eutectic bonding. This construction allows each PMUT in the array to have a dedicated front-end receive amplifier, which together with on-chip analog multiplexing enables individual pixel read-out with high signal-to-noise ratio through minimized parasitic capacitance between the PMUT and the front-end amplifier. Finite element method simulations demonstrate that the waveguides preserve the pressure amplitude of acoustic pulses over distances of 600 ?m. Moreover, the waveguide design demonstrated here enables pixel-by-pixel readout of the ultrasound image due to improved directivity of the PMUT by directing acoustic waves and creating a pressure field with greater spatial uniformity at the end of the waveguide. Pulse-echo imaging experiments conducted using a one-dimensional steel grating demonstrate the array's ability to form a two-dimensional image of a target.

  19. Assessment of strength properties of cemented paste backfill by ultrasonic pulse velocity test.

    PubMed

    Y?lmaz, Tekin; Ercikdi, Bayram; Karaman, Kadir; Külekçi, Gökhan

    2014-07-01

    Ultrasonic pulse velocity (UPV) test is one of the most popular non-destructive techniques used in the assessment of the mechanical properties of concrete or rock materials. In this study, the effects of binder type/dosage, water to cement ratio (w/c) and fines content (<20 ?m) of the tailings on ultrasonic pulse velocity (UPV) of cemented paste backfill (CPB) samples were investigated and correlated with the corresponding unconfined compressive strength (UCS) data. A total of 96 CPB samples prepared at different mixture properties were subjected to the UPV and UCS tests at 7, 14, 28 and 56-days of curing periods. UPV and UCS of CPB samples of ordinary Portland cement (CEM I 42.5 R) and sulphate resistant cement (SRC 32.5) initially increased rapidly, but, slowed down after 14 days. However, UPV and UCS of CPB samples of the blast furnace slag cement (CEM III/A 42.5 N) steadily increased between 7 and 56 days. Increasing binder dosage or reducing w/c ratio and fines content (<20 ?m) increased the UCS and UPV of CPB samples. UPV was found to be particularly sensitive to fines content. UCS data were correlated with the corresponding UPV data. A linear relation appeared to exist between the UCS and UPV of CPB samples. These findings have demonstrated that the UPV test can be reliably used for the estimation of the strength of CPB samples. PMID:24602334

  20. Nanosecond pulse generation in laser with pulsed transmission of Q-switch - Numerical simulation and experiment

    NASA Astrophysics Data System (ADS)

    Andrzejewska, T.; Badziak, J.; Dubicki, A.; Wodnicki, R.

    Numerical analysis results of the pulsed transmission mode (PTM) laser based on a model which takes into account the existence of two coupled photon beams moving in opposite directions, are presented. It is shown that the pulse in the resonator is self-generated as a result of fast switching-off of the losses and nonlinear amplification of the active medium. It is possible to generate pulse durations in typical YAG:Nd lasers from several hundred ps to several ns and with power one order of magnitude higher than in the conventional Q-switched generator. Simultaneous generation of pulses (with an accuracy of 1 ns) in two or three independent trajectories may be obtained. Such factors as initial gain coefficient, shape and duration of the voltage gate driving the Pockels cell, and cavity geometry are also discussed. Theoretical results were verified experimentally.

  1. Sand/cement ratio evaluation on mortar using neural networks and ultrasonic transmission inspection.

    PubMed

    Molero, M; Segura, I; Izquierdo, M A G; Fuente, J V; Anaya, J J

    2009-02-01

    The quality and degradation state of building materials can be determined by nondestructive testing (NDT). These materials are composed of a cementitious matrix and particles or fragments of aggregates. Sand/cement ratio (s/c) provides the final material quality; however, the sand content can mask the matrix properties in a nondestructive measurement. Therefore, s/c ratio estimation is needed in nondestructive characterization of cementitious materials. In this study, a methodology to classify the sand content in mortar is presented. The methodology is based on ultrasonic transmission inspection, data reduction, and features extraction by principal components analysis (PCA), and neural network classification. This evaluation is carried out with several mortar samples, which were made while taking into account different cement types and s/c ratios. The estimated s/c ratio is determined by ultrasonic spectral attenuation with three different broadband transducers (0.5, 1, and 2 MHz). Statistical PCA to reduce the dimension of the captured traces has been applied. Feed-forward neural networks (NNs) are trained using principal components (PCs) and their outputs are used to display the estimated s/c ratios in false color images, showing the s/c ratio distribution of the mortar samples. PMID:18840386

  2. Detection of tissue harmonic motion induced by ultrasonic radiation force using pulse-echo ultrasound and kalman filter

    Microsoft Academic Search

    Yi Zheng; Shigao Chen; Wei Tan; Randall Kinnick; James F. Greenleaf

    2007-01-01

    A method using pulse echo ultrasound and the Kalman filter is developed for detecting submicron harmonic motion induced by ultrasonic radiation force. The method estimates the amplitude and phase of the motion at desired locations within a tissue region with high sensitivity. The harmonic motion generated by the ultrasound radiation force is expressed as extremely small oscillatory Doppler frequency shifts

  3. Standard complex for reproduction and transmission of unit sizes of pulse electric and magnetic intensities in ultrashort pulse range

    Microsoft Academic Search

    K. Yu. Sakharov; O. V. Mikheev; V. A. Turkin; M. I. Dobrotvorsky; A. I. Aleshko

    2010-01-01

    Standard complex for reproduction and transmission of unit sizes of pulse electric and magnetic intensities with pulse leading-edge time no more than 20 ps has been presented. Field-forming system “cone over plane” excited by step voltage signal with amplitude 20 V has been used. Pulse electric intensity has been measured with strip transducer.

  4. Effects of panel density and particle type on the ultrasonic transmission through wood-based panels

    Microsoft Academic Search

    Ulrich Hilbers; Heiko Thoemen; Joerg Hasener; Arno Fruehwald

    Air-coupled ultrasonic inspection for the detection of delaminations inside panels is a widely applied technique in the wood-based\\u000a panel industry. Additionally, the ultrasonic signal is used to monitor the constancy of the production process as unsteady\\u000a material properties and process parameters cause variations in the transmitted ultrasonic signal. This article examines the\\u000a physical effects of air-coupled ultrasonic testing and analyses

  5. A high-voltage transmission-line pulse transformer with very low droop

    Microsoft Academic Search

    P. N. Graneau; J. O. Rossi; M. P. Brown; P. W. Smith

    1996-01-01

    The design, construction, and operational characteristics of a 200 kV transmission line pulse transformer is described. The transformer is wound using a new winding method that enhances the isolation of the output of the transformer from the input. As a result, pulse droop is substantially reduced, minimizing pulse distortion in the transformer. The ways in which both pulse rise time

  6. Finite element modeling of ultrasonic waves produced by a pulsed laser

    SciTech Connect

    Dike, J.J.

    1998-03-01

    As part of an effort to apply laser ultrasonics to stress evaluation, sequential thermal and mechanical finite element analyses were used to simulate heating a region of an aluminum surface by a laser pulse and the stress waves that result. As residual or applied stresses can be related to changes in wave velocities, time-of-flight measurements may be used to determine the stresses. The goal of the effort is to improve time-of-flight measurements, and therefore resolution of the calculated stresses, using calculated waveform shapes in model-based signal processing techniques. Detailed finite element simulations of laser ultrasonics may also be used to aid development of techniques that can generate narrow band ultrasound. Because penetration of Rayleigh waves is frequency dependent, they can be used to obtain information about gradients near a surface. If the frequency of the laser generated Rayleigh waves can be controlled, laser ultrasound becomes a more useful tool for examining gradients in material properties or stresses at the surface of a part. Presented here are some preliminary finite element simulations of laser generation of ultrasound waves. Techniques for using commercial finite element codes are discussed and calculated displacement histories are presented for epicentral and same surface locations. These displacement histories are compared with results from the literature.

  7. Development of an ultrasonic pulse-echo (UPE) technique for aircraft icing studies

    SciTech Connect

    Liu, Yang; Hu, Hui [Department of Aerospace Engineering, Iowa State University, 2271 Howe Hall, Room 1200, Ames, IA 50011 (United States); Chen, Wen-Li [Department of Aerospace Engineering, Iowa State University, 2271 Howe Hall, Room 1200, Ames, IA 50011 (United States); School of Civil Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150090 (China); Bond, Leonard J. [Department of Aerospace Engineering, Iowa State University, 2271 Howe Hall, Room 1200, Ames, IA 50011 (United States); Center for Nondestructive Evaluation, Iowa State University, 1915 Scholl Road, 151 ASC II, Ames, IA 50011 (United States)

    2014-02-18

    Aircraft operating in some cold weather conditions face the risk of icing. Icing poses a threat to flight safety and its management is expensive. Removing light frost on a clear day from a medium-size business jet can cost $300, heavy wet snow removal can cost $3,000 and removal of accumulated frozen/freezing rain can cost close to $10,000. Understanding conditions that lead to severe icing events is important and challenging. When an aircraft or rotorcraft flies in a cold climate, some of the super cooled droplets impinging on exposed aircraft surfaces may flow along the surface prior to freezing and give various forms and shapes of ice. The runback behavior of a water film on an aircraft affects the morphology of ice accretion and the rate of formation. In this study, we report the recent progress to develop an Ultrasonic Pulse-Echo (UPE) technique to provide real-time thickness distribution measurements of surface water flows driven by boundary layer airflows for aircraft icing studies. A series of initial experimental investigations are conducted in an ice wind tunnel employing an array of ultrasonic transducers placed underneath the surface of a flat plate. The water runback behavior on the plate is evaluated by measuring the thickness profile variation of the water film along the surface by using the UPE technique under various wind speed and flow rate conditions.

  8. Pulse-echo ultrasonic imaging method for eliminating sample thickness variation effects

    NASA Technical Reports Server (NTRS)

    Roth, Don J. (Inventor)

    1995-01-01

    A pulse-echo, immersion method for ultrasonic evaluation of a material is discussed. It accounts for and eliminates nonlevelness in the equipment set-up and sample thickness variation effects employs a single transducer, automatic scanning and digital imaging to obtain an image of a property of the material, such as pore fraction. The nonlevelness and thickness variation effects are accounted for by pre-scan adjusments of the time window to insure that the echoes received at each scan point are gated in the center of the window. This information is input into the scan file so that, during the automatic scanning for the material evaluation, each received echo is centered in its time window. A cross-correlation function calculates the velocity at each scan point, which is then proportionalized to a color or grey scale and displayed on a video screen.

  9. Pulse-Echo Ultrasonic Imaging Method for Eliminating Sample Thickness Variation Effects

    NASA Technical Reports Server (NTRS)

    Roth, Don J. (Inventor)

    1997-01-01

    A pulse-echo, immersion method for ultrasonic evaluation of a material which accounts for and eliminates nonlevelness in the equipment set-up and sample thickness variation effects employs a single transducer and automatic scanning and digital imaging to obtain an image of a property of the material, such as pore fraction. The nonlevelness and thickness variation effects are accounted for by pre-scan adjustments of the time window to insure that the echoes received at each scan point are gated in the center of the window. This information is input into the scan file so that, during the automatic scanning for the material evaluation, each received echo is centered in its time window. A cross-correlation function calculates the velocity at each scan point, which is then proportionalized to a color or grey scale and displayed on a video screen.

  10. Pulsed eddy current and ultrasonic data fusion applied to stress measurement

    NASA Astrophysics Data System (ADS)

    Habibalahi, A.; Safizadeh, M. S.

    2014-05-01

    Stress measurement and its variation are key problems in the operating performance of materials. Stress can affect the material properties and the life of components. There are several destructive and nondestructive techniques that are used to measure stress. However, no single nondestructive testing (NDT) technique or method is satisfactory to fully assess stress. This paper presents an NDT data fusion method to improve stress measurement. An aluminum alloy 2024 specimen subjected to stress simulation is nondestructively inspected using pulsed eddy current and ultrasonic techniques. Following these nondestructive examinations, the information gathered from these two NDT methods has been fused using a suitable fuzzy combination operator. The results obtained with these processes are presented in this paper and their efficiency is discussed. It is shown that the fusion of NDT data with a suitable fuzzy operator can be adequate to improve the reliability of stress measurements.

  11. Micromachined ultrasonic transducers: 11.4 MHz transmission in air and Igal Ladabaum, B. T. KhuriYakub, and Dimitri Spoliansky

    E-print Network

    Khuri-Yakub, Butrus T. "Pierre"

    ultrasonic levitation device Rev. Sci. Instrum. 82, 105111 (2011) Modeling of ultrasound transmission through- cause the acoustic impedance of air 400 kg/m 2 s is many orders of magnitude smaller than the impedance

  12. Multiband tissue classification for ultrasonic transmission tomography using spectral profile detection

    NASA Astrophysics Data System (ADS)

    Jeong, Jeong-Won; Kim, Tae-Seong; Shin, Dae-Chul; Do, Synho; Marmarelis, Vasilis Z.

    2004-04-01

    Recently it was shown that soft tissue can be differentiated with spectral unmixing and detection methods that utilize multi-band information obtained from a High-Resolution Ultrasonic Transmission Tomography (HUTT) system. In this study, we focus on tissue differentiation using the spectral target detection method based on Constrained Energy Minimization (CEM). We have developed a new tissue differentiation method called "CEM filter bank". Statistical inference on the output of each CEM filter of a filter bank is used to make a decision based on the maximum statistical significance rather than the magnitude of each CEM filter output. We validate this method through 3-D inter/intra-phantom soft tissue classification where target profiles obtained from an arbitrary single slice are used for differentiation in multiple tomographic slices. Also spectral coherence between target and object profiles of an identical tissue at different slices and phantoms is evaluated by conventional cross-correlation analysis. The performance of the proposed classifier is assessed using Receiver Operating Characteristic (ROC) analysis. Finally we apply our method to classify tiny structures inside a beef kidney such as Styrofoam balls (~1mm), chicken tissue (~5mm), and vessel-duct structures.

  13. High-voltage subnanosecond pulse transformer composed of parallel-strip transmission lines

    Microsoft Academic Search

    Akira Homma

    1999-01-01

    A subnanosecond pulse isolation transformer composed of a parallel-strip transmission line was designed, constructed, and tested. The insertion loss and effective time constant of the transformer were calculated with transmission line analysis. To facilitate the analysis, the reflection diagram method was applied. The experiments indicate that the transformer can transmit subnanosecond rise time pulses across a potential difference of 100

  14. Noninvasive and localized neuronal delivery using short ultrasonic pulses and microbubbles.

    PubMed

    Choi, James J; Selert, Kirsten; Vlachos, Fotios; Wong, Anna; Konofagou, Elisa E

    2011-10-01

    Focused ultrasound activation of systemically administered microbubbles is a noninvasive and localized drug delivery method that can increase vascular permeability to large molecular agents. Yet the range of acoustic parameters responsible for drug delivery remains unknown, and, thus, enhancing the delivery characteristics without compromising safety has proven to be difficult. We propose a new basis for ultrasonic pulse design in drug delivery through the blood-brain barrier (BBB) that uses principles of probability of occurrence and spatial distribution of cavitation in contrast to the conventionally applied magnitude of cavitation. The efficacy of using extremely short (2.3 ?s) pulses was evaluated in 27 distinct acoustic parameter sets at low peak-rarefactional pressures (0.51 MPa or lower). The left hippocampus and lateral thalamus were noninvasively sonicated after administration of Definity microbubbles. Disruption of the BBB was confirmed by delivery of fluorescently tagged 3-, 10-, or 70-kDa dextrans. Under some conditions, dextrans were distributed homogeneously throughout the targeted region and accumulated at specific hippocampal landmarks and neuronal cells and axons. No histological damage was observed at the most effective parameter set. Our results have broadened the design space of parameters toward a wider safety window that may also increase vascular permeability. The study also uncovered a set of parameters that enhances the dose and distribution of molecular delivery, overcoming standard trade-offs in avoiding associated damage. Given the short pulses used similar to diagnostic ultrasound, new critical parameters were also elucidated to clearly separate therapeutic ultrasound from disruption-free diagnostic ultrasound. PMID:21930942

  15. 10-Gbit\\/s RZ pulses using an all-silicon nonlinear transmission line integrated circuit

    Microsoft Academic Search

    Martin Birk; Leda M. Lunardi; Alan H. Gnauck; Hermann Schumacher; Dag Behammer

    2000-01-01

    We demonstrate 25 ps wide electrical pulses using a nonlinear transmission line (NLTL) integrated circuit fabricated on high-resistivity silicon. These pulses are modulated electrically and used to drive a LiNbO3 Mach-Zehnder modulator to create optical 10 Gbit\\/s RZ data with 27 ps pulse width

  16. Adaptive Pulse Repetition Frequency Technique for an Ultrasonic Transit-Time Gas Flowmeter for Hot Pulsating Gases

    Microsoft Academic Search

    Mario Kupnik; Andreas Schröder; Paul O'Leary; Ewald Benes; Martin Gröschl

    2006-01-01

    A technique of using an adaptive pulse repetition frequency (PRF) to operate an ultrasonic contrapropagation transit-time gas flowmeter (UFM) is introduced. This adaptive PRF technique allows transient measurements of hot (up to 450 degC) and pulsating (up to 1.5 kHz) gas flows. Such conditions occur in the exhaust gas of a combustion engine. Here, a UFM with the widely used

  17. 3-D Surface Depression Profiling Using High Frequency Focused Air-Coupled Ultrasonic Pulses

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Kautz, Harold E.; Abel, Phillip B.; Whalen, Mike F.; Hendricks, J. Lynne; Bodis, James R.

    1999-01-01

    Surface topography is an important variable in the performance of many industrial components and is normally measured with diamond-tip profilometry over a small area or using optical scattering methods for larger area measurement. This article shows quantitative surface topography profiles as obtained using only high-frequency focused air-coupled ultrasonic pulses. The profiles were obtained using a profiling system developed by NASA Glenn Research Center and Sonix, Inc (via a formal cooperative agreement). (The air transducers are available as off-the-shelf items from several companies.) The method is simple and reproducible because it relies mainly on knowledge and constancy of the sound velocity through the air. The air transducer is scanned across the surface and sends pulses to the sample surface where they are reflected back from the surface along the same path as the incident wave. Time-of-flight images of the sample surface are acquired and converted to depth/surface profile images using the simple relation (d = V*t/2) between distance (d), time-of-flight (t), and the velocity of sound in air (V). The system has the ability to resolve surface depression variations as small as 25 microns, is useable over a 1.4 mm vertical depth range, and can profile large areas only limited by the scan limits of the particular ultrasonic system. (Best-case depth resolution is 0.25 microns which may be achievable with improved isolation from vibration and air currents.) The method using an optimized configuration is reasonably rapid and has all quantitative analysis facilities on-line including 2-D and 3-D visualization capability, extreme value filtering (for faulty data), and leveling capability. Air-coupled surface profilometry is applicable to plate-like and curved samples. In this article, results are shown for several proof-of-concept samples, plastic samples burned in microgravity on the STS-54 space shuttle mission, and a partially-coated cylindrical ceramic composite sample. Impressive results were obtained for all samples when compared with diamond-tip profiles and measurements from micrometers. The method is completely nondestructive, noninvasive, non-contact and does not require light-reflective surfaces.

  18. Modeling and Phantom Studies of Ultrasonic Wall Shear Rate Measurements Using Coded Pulse Excitation

    PubMed Central

    Tsou, Jean K.; Liu, Jie; Insana, Michael F.

    2009-01-01

    Wall shear rate (WSR) is the derivative of blood velocity with respect to vessel radius at the endothelial cell (EC) surface. The product of WSR and blood viscosity is the wall shear stress (WSS) that has been identified as an important factor for atherosclerosis development. High echo signal-to-noise ratio (eSNR) and high spatial resolution are crucial for minimizing the errors in WSR estimates. By transmitting coded pulses with time-bandwidth product greater than one, high eSNR from weak blood scatter can be achieved without increasing instantaneous power or sacrificing spatial resolution. This paper summarizes a series of measurements in a straight tube (5-mm diameter), constant velocity flow phantom using a 10 MHz transducer (60% bandwidth, f/1.5) imaged with a 72° Doppler angle, 125 MHz sampling frequency and 1 kHz pulse repetition frequency. Measurements were made using a frequency-modulated (FM) code, phase-modulated (PM) codes, and uncoded broadband and narrow band pulse transmissions. Both simulation and experimental results show that coded-pulse excitation increases accuracy and precision in WSR estimation for laminar flow over a broad range of peak velocity values when compared to standard pulsing techniques in noise-limited conditions (eSNR < 30 dB). The code sequence and its length are selected to balance range lobe suppression with eSNR and echo coherence enhancements to minimize WSR errors. In our study, the combination of an eight bit Optimal coded pulse with a Wiener compression filter yielded the highest WSR estimation performance. PMID:16615576

  19. Improvements in the ultrasonic contrast of targeted perfluorocarbon nanoparticles using an acoustic transmission line model

    Microsoft Academic Search

    Jon N. Marsh; C. S. Hall; M. J. Scott; R. W. Fuhrhop; P. J. Gaffney; S. A. Wickline; G. M. Lanza

    2002-01-01

    Targeted acoustic contrast agents offer the potential for sensitive ultrasonic detection of pathologic tissues. We have previously reported the development of a ligand-targeted, lipid-encapsulated, liquid perfluorodichlorooctane ultrasonic contrast system with a small nominal particle size (approximately 250-nm diameter)Perfluorocarbon nanoparticles substantially increase reflectivity when bound to targeted surfaces, and we propose that this system can be approximated physically as a simple,

  20. Method and apparatus for ultrasonic doppler velocimetry using speed of sound and reflection mode pulsed wideband doppler

    DOEpatents

    Shekarriz, Alireza (Kennewick, WA); Sheen, David M. (Richland, WA)

    2000-01-01

    According to the present invention, a method and apparatus rely upon tomographic measurement of the speed of sound and fluid velocity in a pipe. The invention provides a more accurate profile of velocity within flow fields where the speed of sound varies within the cross-section of the pipe. This profile is obtained by reconstruction of the velocity profile from the local speed of sound measurement simultaneously with the flow velocity. The method of the present invention is real-time tomographic ultrasonic Doppler velocimetry utilizing a to plurality of ultrasonic transmission and reflection measurements along two orthogonal sets of parallel acoustic lines-of-sight. The fluid velocity profile and the acoustic velocity profile are determined by iteration between determining a fluid velocity profile and measuring local acoustic velocity until convergence is reached.

  1. Microwave pulse generation using the Bragg cutoff of a nonlinear transmission line

    Microsoft Academic Search

    Keith G. Lyon; Edwin C. Kan

    2008-01-01

    Nonlinear transmission lines (NLTL) have received considerable attention for their frequency conversion, fast pulse generation, and rise\\/falltime compression properties. Here we present a new mode of operation for the NLTL which uses falltime compression to generate short RF pulses near the Bragg cutoff frequency. While this phenomenon has been reported in circuit model simulations, we demonstrate, to our knowledge, its

  2. Fast bipolar voltage pulse generator using nonlinear transmission line for exciting UV light source

    Microsoft Academic Search

    K. Yasuoka; H. Takahashi; M. Miyake; S. Ibuka; S. Ishii; Y. Uchida; H. Yasui

    1997-01-01

    Fast bipolar voltage pulses were generated for exciting a dielectric coated discharge system by using a nonlinear transmission line (NLTL) which included nonlinear capacitors. The energy transfer efficiency of a basic resonant circuit consisting of a nonlinear capacitor was evaluated from the viewpoint of efficient energy transfer. The simulation results of the pulsed laser discharge show that the nonlinear capacitor

  3. Voltage amplification effect of nonlinear transmission lines for fast high voltage pulse generation

    Microsoft Academic Search

    Shinji Ibuka; Mitsuru Ohnishi; Takeshi Yamada; Koichi Yasuoka; Shozo Ishii; Kwang-Cheol Ko

    1997-01-01

    The authors have proposed a new scheme of high voltage pulse generation utilizing a nonlinear transmission line (NLTL). The scheme is based on the voltage amplification effect of the process of the formation and collision of solitons in the NLTL with ferroelectric ceramic capacitors. Using the head-on collision scheme of two solitons, a fast high voltage pulse with 11 kV

  4. Ultrasonic probe deployment device for increased wave transmission and rapid area scan inspections

    DOEpatents

    DiMambro, Joseph (Placitas, NM); Roach, Dennis P. (Albuquerque, NM); Rackow, Kirk A. (Albuquerque, NM); Nelson, Ciji L. (Albuquerque, NM); Dasch, Cameron J. (Boomfield Hills, MI); Moore, David G. (Albuquerque, NM)

    2012-01-03

    An ultrasonic probe deployment device in which an ultrasound-transmitting liquid forms the portion of the ultrasonic wave path in contact with the surface being inspected (i.e., the inspection surface). A seal constrains flow of the liquid, for example preventing the liquid from surging out and flooding the inspection surface. The seal is not rigid and conforms to variations in the shape and unevenness of the inspection surface, thus forming a seal (although possibly a leaky seal) around the liquid. The probe preferably is held in place to produce optimum ultrasonic focus on the area of interest. Use of encoders can facilitate the production of C-scan area maps of the material being inspected.

  5. Ultrasonic probe deployment device for increased wave transmission and rapid area scan inspections

    SciTech Connect

    DiMambro, Joseph; Roach, Dennis P; Rackow, Kirk A; Nelson, Ciji L; Dasch, Cameron J; Moore, David G

    2013-02-12

    An ultrasonic probe deployment device in which an ultrasound-transmitting liquid forms the portion of the ultrasonic wave path in contact with the surface being inspected (i.e., the inspection surface). A seal constrains flow of the liquid, for example preventing the liquid from surging out and flooding the inspection surface. The seal is not rigid and conforms to variations in the shape and unevenness of the inspection surface, thus forming a seal (although possibly a leaky seal) around the liquid. The probe preferably is held in place to produce optimum ultrasonic focus on the area of interest. Use of encoders can facilitate the production of C-scan area maps of the material being inspected.

  6. Generation of kilovolt-subnanosecond pulses using a nonlinear transmission line

    Microsoft Academic Search

    R. J. Baker; D. J. Hodder; B. P. Johnson; P. C. Subedi; D. C. Williams

    1993-01-01

    A nonlinear transmission line (NLTL) is used to speed up the risetime of high voltage (>1 kV) pulses. The theory of the NLTL is reviewed and practical implementations and limitations are discussed. An NLTL is used to generate a 1.5 kV pulse with a risetime of 500 ps. A discussion of generating pulses with amplitudes greater than 3.5 kV and

  7. Fast high-voltage pulse generator with nonlinear transmission line for high repetition rate operation

    Microsoft Academic Search

    Shinji Ibuka; K. Abe; T. Miyazawa; A. Ishii; S. Ishii

    1997-01-01

    A new application of the nonlinear transmission line (NLTL) for high-voltage pulse generation is reported. In this NLTL, a rise time of an input pulse voltage of 20-kV amplitude can be reduced from 500 to less than 120 ns. Using this circuit, we demonstrated excitation of a pulsed CO2 laser, and obtained output energy of 129 mJ at an efficiency

  8. Generation of kilovolt-subnanosecond pulses using a nonlinear transmission line

    Microsoft Academic Search

    R J Baker; J Hodder; B P Johnson; PC Subedi; C Williams

    1993-01-01

    A nonlinear transmission line (NLTL) is used to speed up the risetime of high voltage (> 1 kV) pulses. The theory of the NL TL is reviewed and practical implementations and limitations are discussed. An NLTL is used to generate a 1.5 kV pulse with a risetime of 500 ps. The note concludes with a discussion of generating pulses with

  9. Heat pulse transmission across a solid He 1 interface

    Microsoft Academic Search

    N. E. Hager III

    1981-01-01

    A study of the thermal boundary resistance (Kapitza Resistance) between a solid crystal and liquid Helium 1 was made. Measurements were made by use of the fast heat pulse technique, allowing a direct observation of phonons emitted from the solid surface into the helium. Separate pulses originating from longitudinal and transverse crystal modes was resolved at the detector. An initial

  10. Measurement of linear-shaped charge jet penetration using an ultrasonic pulse echo technique

    SciTech Connect

    Hallett, S.G.; Gieske, J.H.; Walkington, P.D.

    1986-04-01

    A method for ultrasonically measuring the depth of penetration resulting from the detonation of aluminum linear-shaped charge (ALSC) into an aluminum target is described. The technique succeeds in determining the extent of jet penetration with exceptional accuracy and requires substantially less time to acquire the data than prior methods. Statistically, the greater number of points used to characterize the groove profile ultrasonically is superior to the measuring methods previously employed. These advantages suggest that the ultrasonic technique may potentially replace the laborious procedures currently used to measure jet penetration from ALSC detonation.

  11. Ultrasonic pulser-receiver

    DOEpatents

    Taylor, Steven C.

    2006-09-12

    Ultrasonic pulser-receiver circuitry, for use with an ultrasonic transducer, the circuitry comprising a circuit board; ultrasonic pulser circuitry supported by the circuit board and configured to be coupled to an ultrasonic transducer and to cause the ultrasonic transducer to emit an ultrasonic output pulse; receiver circuitry supported by the circuit board, coupled to the pulser circuitry, including protection circuitry configured to protect against the ultrasonic pulse and including amplifier circuitry configured to amplify an echo, received back by the transducer, of the output pulse; and a connector configured to couple the ultrasonic transducer directly to the circuit board, to the pulser circuitry and receiver circuitry, wherein impedance mismatches that would result if the transducer was coupled to the circuit board via a cable can be avoided.

  12. Time-resolved optical transmission of pulsed laser-irradiated silicon

    SciTech Connect

    Lee, M.C.; Lo, H.W.; Aydinli, A.; Compaan, A.

    1980-10-20

    The time-resolved optical transmission of silicon has been observed at lambda = 1.15 microns during irradiation by an 8 nsec pulsed laser at 485 nm with several energy densities in the range of .25 to 1.2 J/sq cm. The transmission exhibits a sudden brief drop consistent with the rise and fall of the reflectivity enhancement. However, the transmission does not exhibit the strong absorption expected of molten silicon with a skin depth of approx. 100A.

  13. Ultrasonic monitoring of material processing using clad buffer rod sensors

    Microsoft Academic Search

    Demartonne Ramos Franca

    2001-01-01

    Ultrasonic sensors and techniques are developed for in-line monitoring of polymer extrusion, cleanliness of molten metals and liquid flow speed at elevated temperature. Pulse-echo mode is used for the first two processes, while the through-transmission mode is applied in the third one. The ultrasonic probe consists of high performance clad buffer rods with different dimensions to thermally isolate the commercial

  14. Finger blood content, light transmission, and pulse oximetry errors.

    PubMed

    Craft, T M; Lawson, R A; Young, J D

    1992-01-01

    The changes in light emitting diode current necessary to maintain a constant level of light incident upon a photodetector were measured in 20 volunteers at the two wavelengths employed by pulse oximeters. Three states of finger blood content were assessed; exsanguinated, hyperaemic, and normal. The changes in light emitting diode current with changes in finger blood content were small and are not thought to represent a significant source of error in saturation as measured by pulse oximetry. PMID:1536406

  15. Full circuit calculation for electromagnetic pulse transmission in a high current facility

    NASA Astrophysics Data System (ADS)

    Zou, Wenkang; Guo, Fan; Chen, Lin; Song, Shengyi; Wang, Meng; Xie, Weiping; Deng, Jianjun

    2014-11-01

    We describe herein for the first time a full circuit model for electromagnetic pulse transmission in the Primary Test Stand (PTS)—the first TW class pulsed power driver in China. The PTS is designed to generate 8-10 MA current into a z -pinch load in nearly 90 ns rise time for inertial confinement fusion and other high energy density physics research. The PTS facility has four conical magnetic insulation transmission lines, in which electron current loss exists during the establishment of magnetic insulation. At the same time, equivalent resistance of switches and equivalent inductance of pinch changes with time. However, none of these models are included in a commercially developed circuit code so far. Therefore, in order to characterize the electromagnetic transmission process in the PTS, a full circuit model, in which switch resistance, magnetic insulation transmission line current loss and a time-dependent load can be taken into account, was developed. Circuit topology and an equivalent circuit model of the facility were introduced. Pulse transmission calculation of shot 0057 was demonstrated with the corresponding code FAST (full-circuit analysis and simulation tool) by setting controllable parameters the same as in the experiment. Preliminary full circuit simulation results for electromagnetic pulse transmission to the load are presented. Although divergences exist between calculated and experimentally obtained waveforms before the vacuum section, consistency with load current is satisfactory, especially at the rising edge.

  16. Precise sound source localisation of dolphin biosonar pulse transmissions

    Microsoft Academic Search

    Eric L. Ferguson

    2010-01-01

    Dolphins rely on auditory perception for survival and their biological sonars (or biosonars) equip them for life in marine environments. Dolphins probe their habitats using sequences of short underwater sound pulses (or clicks) for echolocation that enable them to navigate and avoid collisions with natural objects in the environment, and to detect and discriminate between prey, predators, and companions. In

  17. Pulse-echo phased array ultrasonic inspection of pultruded rod stitched efficient unitized structure (PRSEUS)

    SciTech Connect

    Johnston, P. H. [NASA Langley Research Center, Hampton, VA 23681 (United States)

    2011-06-23

    A PRSEUS test article was subjected to controlled impact on the skin face followed by static and cyclic axial compressions. Phased array ultrasonic inspection was conducted before impact, and after each of the test conditions. A linear phased array probe with a manual X-Y scanner was used for interrogation. Ultrasound showed a delamination between the skin and stringer flange adjacent to the impact. As designed, the stitching in the flange arrested the lateral flaw formation. Subsequent ultrasonic data showed no delamination growth due to continued loading.

  18. Reflection and Transmission of Pulsed Electromagnetic Fields through Multilayered

    E-print Network

    Oughstun, Kurt

    skin, fat and muscle is analyzed. The fre- quency dependent reflection and transmission coeffi- cients of the multilayer stack are computed using the transfer matrix method. Each of the three tissues is modeled based on empirical data suggest penetration depths much greater than that previously described by simple

  19. Subpicosecond measurements of the response of Josephson transmission lines to large current pulses

    Microsoft Academic Search

    Marc Currie; Roman Sobolewski; Thomas Y. Hsiang

    1999-01-01

    Josephson transmission lines (JTLs) are commonly used as signal interconnects in single-flux quantum (SFQ) circuits. They are also used, however, to transform arbitrary waveforms into SFQ pulses. Here we use a low-temperature electro-optic sampling system with subpicosecond resolution to observe the response of a JTL to a picosecond input pulse. Previously, this system has been used to directly observe SFQ

  20. Fiber transmission for sub-500-fs pulses using a dispersion-compensating fiber

    Microsoft Academic Search

    Cheng-Chun Chang; Andrew M. Weiner

    1997-01-01

    We report transmission of ~60-fs and ~245-fs pulses, respectively, over 42-m and 2.5-km fiber links which consist of standard single-mode fibers (SMF) concatenated with dispersion-compensating fibers (DCF). The experiments using very short pulses (~60 fs) over a short fiber length (~42 m) demonstrate the ability to achieve simultaneous dispersion and dispersion slope compensation using this technique. Femtosecond spectral interferometry measurements

  1. Microprocessor-based ultrasonic height controller for sugarcane harvesters 

    E-print Network

    Coad, Craig Allan

    1980-01-01

    SUGARCANE CUTTING HEIGHT CONTROL ALGORITHM Introduction. Lost Echo Discrimination. vi 7 9 9 12 17 21 21 21 24 27 33 33 36 37 38 38 40 44 44 46 48 49 49 49 The Need for Two Averages Methods of Averaging. LABORATORY TEST...-stalk discrimination and signal averaging. ULTRASONIC SENSING PRINCIPLES Basic Conce t Proximity of a reflecting target to an ultrasonic transducer is indicated by the time elapsi. ng between the transmission of an ultrasonic pulse and the reception of the echo...

  2. Measurement of linear-shaped charge jet penetration using an ultrasonic pulse echo technique

    Microsoft Academic Search

    S. G. Hallett; J. H. Gieske; P. D. Walkington

    1986-01-01

    A method for ultrasonically measuring the depth of penetration resulting from the detonation of aluminum linear-shaped charge (ALSC) into an aluminum target is described. The technique succeeds in determining the extent of jet penetration with exceptional accuracy and requires substantially less time to acquire the data than prior methods. Statistically, the greater number of points used to characterize the groove

  3. Coherent transmission of an ultrasonic shock wave through a multiple scattering medium.

    PubMed

    Viard, Nicolas; Giammarinaro, Bruno; Derode, Arnaud; Barrière, Christophe

    2013-08-01

    We report measurements of the transmitted coherent (ensemble-averaged) wave resulting from the interaction of an ultrasonic shock wave with a two-dimensional random medium. Despite multiple scattering, the coherent waveform clearly shows the steepening that is typical of nonlinear harmonic generation. This is taken advantage of to measure the elastic mean free path and group velocity over a broad frequency range (2-15 MHz) in only one experiment. Experimental results are found to be in good agreement with a linear theoretical model taking into account spatial correlations between scatterers. These results show that nonlinearity and multiple scattering are both present, yet uncoupled. PMID:24032956

  4. Optimized transmission-line impedance transformers for petawatt-class pulsed-power accelerators

    NASA Astrophysics Data System (ADS)

    Welch, D. R.; Genoni, T. C.; Rose, D. V.; Bruner, N. L.; Stygar, W. A.

    2008-03-01

    We have developed 1D analytic and 2D fully electromagnetic models of radial transmission-line impedance transformers. The models have been used to quantify the power-transport efficiency and pulse sharpening of such transformers as a function of voltage pulse width and impedance profile. For the cases considered, we find that in the limit as ??0 (where ? is the ratio of the pulse width to the one-way transit time of the transformer), the transport efficiency is maximized when the impedance profile is exponential. As ? increases from zero, the optimum profile gradually deviates from an exponential. A numerical procedure is presented that determines the optimum profile for a given pulse shape and width. The procedure can be applied to optimize the design of impedance transformers used in petawatt-class pulsed-power accelerators.

  5. Pulse sharpening and soliton generation with nonlinear transmission lines for producing RF bursts

    Microsoft Academic Search

    Jason M. Sanders; Yung-Hsu Lin; Richard Ness; Andras Kuthi; Martin Gundersen

    2010-01-01

    Nonlinear transmission lines (NLTL) are being designed and built to extend the range of available Ultra- Wide Band (UWB) and High Power RF pulse generation technology, especially in the area of high repetition rate microwave burst generation (1). The NLTL approach to UWB and RF generation eliminates the need for the electron beam, vacuum system, and magnets required in conventional

  6. Generation of sub-GW RF pulses in nonlinear transmission lines

    Microsoft Academic Search

    V.V. Rostov; N. M. Bykov; D. N. Bykov; A. V. Gunin; A. I. Klimov; O. B. Kovalchuk; V. O. Kutenkov; I. V. Romanchenko

    2009-01-01

    The paper presents the results of recent experiments on the generation of subgigawatt RF pulses using two types of nonlinear transmission lines (NLTL's). In the high-voltage coaxial lines, we used: (1) periodic gas gap structure and (2) uniformly loaded saturated ferrite with axial bias. The concept of the first element is based on the in-phase composition of RF fields produced

  7. Transient analysis of tapered transmission lines used as transformers for short pulses

    Microsoft Academic Search

    Yue Ping Tang; Zheng Li; Song Yue Tang

    1995-01-01

    The transient behavior of tapered transmission lines is studied in detail by investigating their step responses by an improved method of characteristics. We take interest in the first arriving wave and the following dropping process at the load end which play important roles in determining the response waveform and power coupling efficiency under short pulse excitation. Numerical results show that,

  8. Numerical study on nonlinear pulse transmission in a fiber link with periodical dispersion slope compensation

    Microsoft Academic Search

    Joji Maeda; Yutaka Fukuchi

    2005-01-01

    In fiber links with a bit rate greater than 100 Gb\\/s per wavelength channel, the third-order dispersion (TOD), known as the dispersion slope, becomes a major factor that limits transmission capabilities. This paper presents a numerical study on the propagation of picosecond pulses in anomalous dispersion fibers, the dispersion slope of which is periodically compensated for by lumped compensators. In

  9. AVOIDANCE OF DIRECT CURRENT VOLTAGE DISPLACEMENTS IN THE TRANSMISSION OF HIGH PULSE RATES

    Microsoft Academic Search

    1963-01-01

    The problem of avoiding direct current voltage displacements in the ; transmission of hlgh pulse rates is illustrated by a discussion of the principles ; and properties of an energy spectrometer. The conditions for avoidance of direct ; current displacements are derived. The displacements measured in the Co⁶° ; spectrum with a Nal crystal were -- 1 v without parallel

  10. The use of broadband acoustic transducers and pulse-compression techniques for air-coupled ultrasonic imaging

    Microsoft Academic Search

    T. H. Gan; D. A. Hutchins; D. R. Billson; D. W. Schindel

    2001-01-01

    A pulse-compression technique has been applied to air-coupled testing of solid materials. Capacitance transducers were used to generate wide bandwidth swept-frequency (chirp) signals in air, which were then used to measure and image solid samples in through transmission. The results demonstrate that such signal processing techniques lead to an improvement in the signal to noise ratio and timing accuracy for

  11. Effects of self-phase modulation on sub-500 fs pulse transmission over dispersion compensated fiber links

    Microsoft Academic Search

    Shuai Shen; Cheng-Chun Chang; Harshad P. Sardesai; Vikrant Binjrajka; Andrew M. Weiner

    1999-01-01

    The effects of nonlinearity on sub-500 fs pulse transmission over dispersion compensated fiber links using dispersion compensating fiber technique are investigated numerically and experimentally. The pulse broadening and recompression ratio of the 2.5-km transmission link is over 300. The postcompensated and precompensated links are compared when the input pulse energy ranges from 15 to 159 pJ. At high powers, self-phase

  12. A high-voltage transmission-line pulse transformer with very low droop

    NASA Astrophysics Data System (ADS)

    Graneau, P. N.; Rossi, J. O.; Brown, M. P.; Smith, P. W.

    1996-07-01

    The design, construction, and operational characteristics of a 200 kV transmission line pulse transformer is described. The transformer is wound using a new winding method that enhances the isolation of the output of the transformer from the input. As a result, pulse droop is substantially reduced, minimizing pulse distortion in the transformer. The ways in which both pulse rise time and droop can be further improved are investigated using a simple model for the transformer. The frequency response performance of the transformer is also described and modeled. As a result, it is shown that this type of transformer has the potential to be used as a high-frequency, continuously excited power transformer.

  13. Direct-detection DWDM and information transmission using infrared acousto-optic femtosecond pulse shaping

    NASA Astrophysics Data System (ADS)

    Huang, Feng; Warren, Warren S., Sr.

    2004-11-01

    Acousto-optic modulator (AOM)-based pulse shaping permits precise spectrum slicing, which is useful for dense wavelength division multiplexed (DWDM)-based architectures. In essence, this method uses microsecond-duration radio frequency pulses to completely control the spectra of femtosecond laser pulses, hence achieves dramatic temporal data compression. We demonstrated the AOM pulse shaper as the modulator and a CCD camera with 256 pixels as the receiver. The spectrum of a 200 fs Erbium Doped Fiber Laser (EDFL) pulse was dispersed across the AOM"s aperture (FWHM was 35 nm) and was then modulated in a conventional pulse shaper. We tested 87 channels with channel-spacing of 0.41 nm using a 518-MHz modulator, and 120 channels with channel-spacing of 0.29 nm using a 148-MHz modulator (in each case a 0.1 nm guard band was used). Starting from the original pulses, this modulation creates time slots of 43 ps and 63.4 ps respectively. The equivalent speed of the transmission will be 2.0 Tb/s and 1.9 Tb/s in a highly multiplexed system. The spectral efficiencies achieved in this experiment were ~46%, approaching the theoretical limit of 50% for On-Off Keying (OOK) modulation. A benchmark image was successfully sent over the test bed.

  14. Parallel transmission RF pulse design for eddy current correction at ultra high field

    NASA Astrophysics Data System (ADS)

    Zheng, Hai; Zhao, Tiejun; Qian, Yongxian; Ibrahim, Tamer; Boada, Fernando

    2012-08-01

    Multidimensional spatially selective RF pulses have been used in MRI applications such as B1 and B0 inhomogeneities mitigation. However, the long pulse duration has limited their practical applications. Recently, theoretical and experimental studies have shown that parallel transmission can effectively shorten pulse duration without sacrificing the quality of the excitation pattern. Nonetheless, parallel transmission with accelerated pulses can be severely impeded by hardware and/or system imperfections. One of such imperfections is the effect of the eddy current field. In this paper, we first show the effects of the eddy current field on the excitation pattern and then report an RF pulse the design method to correct eddy current fields caused by the RF coil and the gradient system. Experimental results on a 7 T human eight-channel parallel transmit system show substantial improvements on excitation patterns with the use of eddy current correction. Moreover, the proposed model-based correction method not only demonstrates comparable excitation patterns as the trajectory measurement method, but also significantly improves time efficiency.

  15. Parallel transmission RF pulse design for eddy current correction at ultra high field.

    PubMed

    Zheng, Hai; Zhao, Tiejun; Qian, Yongxian; Ibrahim, Tamer; Boada, Fernando

    2012-08-01

    Multidimensional spatially selective RF pulses have been used in MRI applications such as B? and B? inhomogeneities mitigation. However, the long pulse duration has limited their practical applications. Recently, theoretical and experimental studies have shown that parallel transmission can effectively shorten pulse duration without sacrificing the quality of the excitation pattern. Nonetheless, parallel transmission with accelerated pulses can be severely impeded by hardware and/or system imperfections. One of such imperfections is the effect of the eddy current field. In this paper, we first show the effects of the eddy current field on the excitation pattern and then report an RF pulse the design method to correct eddy current fields caused by the RF coil and the gradient system. Experimental results on a 7 T human eight-channel parallel transmit system show substantial improvements on excitation patterns with the use of eddy current correction. Moreover, the proposed model-based correction method not only demonstrates comparable excitation patterns as the trajectory measurement method, but also significantly improves time efficiency. PMID:22789452

  16. Parallel Transmission RF Pulse Design for Eddy Current Correction at Ultra High Field

    PubMed Central

    Zheng, Hai; Zhao, Tiejun; Qian, Yongxian; Ibrahim, Tamer; Boada, Fernando

    2012-01-01

    Multidimensional spatially selective RF pulses have been used in MRI applications such as B1 and B0 inhomogeneities mitigation. However, the long pulse duration has limited their practical applications. Recently, theoretical and experimental studies have shown that parallel transmission technique can effectively shorten pulse duration without sacrificing the quality of the excitation pattern. Nonetheless, parallel transmission with accelerated pulses can be severely impeded by hardware and/or system imperfections. One of such imperfections is the effect of the eddy current field. In this paper, we first show the effects of the eddy current field on the excitation pattern and then report RF pulse design method to correct eddy current fields caused by the RF coil and gradient system. Experimental results on a 7T human eight-channel transmit system show substantial improvements on excitation patterns with the use of eddy current correction. Moreover, the proposed model-based correction method not only demonstrates the comparable excitation pattern as the trajectory measurement method, but also significantly improves time efficiency. PMID:22789452

  17. Microstrip GaAs nonlinear transmission-line (NLTL) harmonic and pulse generators

    Microsoft Academic Search

    D. Salameh; D. Linton

    1999-01-01

    The design, simulation, and measurement of novel microstrip-based GaAs monolithic-microwave integrated-circuit (MMIC) nonlinear transmission-line (NLTL) harmonic and pulse generators is reported. The advantages of microstrip-based NLTL's are compressed size and flexible aspect ratio where these parameters are important in standard MMIC foundries. The disadvantages are the need for via holes causing limited bandwidth (up to 40 GHz) and lower performance

  18. Design of pulsed waveform oscillators with a short nonlinear transmission line

    Microsoft Academic Search

    M. Ponton; F. Ramirez; A. Suarez

    2010-01-01

    In this paper we present a new methodology for the design of pulsed-waveform oscillators. The design is based on the use of a short section of nonlinear transmission line (NLTL), constituting the load of a transistor-based subnetwork exhibiting negative resistance. The oscillation start-up conditions are imposed at a transistor port different from the one at which the NLTL is connected,

  19. Transmission Improvement in Ultralong Dispersion-Managed Soliton WDM Systems by Using Pulses With Different Widths

    NASA Astrophysics Data System (ADS)

    Lakoba, T. I.

    2005-09-01

    It was shown that one can improve transmission performance in ultra-long-haul wavelength-division-multiplexed (WDM) systems by matching the input pulsewidth to the path-averaged dispersion (PAD) in the line. Wider pulses should be used for higher values of PAD, and vice versa. It was also noted that this pulsewidth selection is only effective in the dispersion-managed soliton (DMS) propagation regime but not in the chirped return-to-zero (CRZ) regime.

  20. Continuous monitoring of a dam flush in a shallow river using two crossing ultrasonic transmission lines

    NASA Astrophysics Data System (ADS)

    Kawanisi, Kiyosi; Razaz, Mahdi; Yano, Jyunki; Ishikawa, Kazuhiko

    2013-05-01

    Continuous measurements of streamflow and water temperature were carried out in a shallow gravel-bed river during dam flushing operations using a new shallow acoustic system with two crossing transmission lines. The fluvial acoustic system (FAS) was equipped with four 25 kHz broadband omnidirectional transducers. The reciprocal sound transmissions were performed between the two pairs of acoustic stations, located on both sides of the river. The four-station FAS enabled the measurement of the stream direction in addition to the depth- and range-averaged sound speed, and therefore water velocity. Discharge values computed from FAS reports were compared to those estimated by the moving-boat acoustic Doppler current profiler (ADCP) and rating curve (RC) methods. FAS estimates were in good agreement with ADCP and RC estimates over a range of 50 to 180 m3 s-1. The temperature gradients induced strong sound scattering for the 25 kHz FAS. The fine suspended sediment particles also induced a gradual decrease in the signal-to-noise ratio of the FAS. Nevertheless, the FAS has been proved to be a reliable and accurate technique for the continuous measurement of cross-sectional average velocity/water temperature.

  1. Laser pulse transmission through the water breakdown plasma in laser shock peening

    SciTech Connect

    Wu Benxin; Shin, Yung C. [Center for Laser-Based Manufacturing Purdue University, West Lafayette, Indiana 47907 (United States)

    2006-01-23

    Laser shock peening (LSP) under a water confinement regime can produce plasma pressures on the target surface four times higher and 2-3 times longer than that under direct regime configurations. However, when the laser power density is above some threshold, a breakdown plasma occurs in water, which screens a significant amount of the incident laser pulse and therefore limits the magnitude and duration of the pressure induced on the target surface. A self-closed numerical model that can simulate the laser pulse transmission through the breakdown plasma generated in water during LSP has rarely been reported in literature. In this work, the breakdown plasma is simulated by solving an electron rate equation coupled with a Maxwell's wave equation. The peak irradiance and duration of the laser pulse transmitted through the breakdown plasma predicted from the model can be correlated reasonably well with experimental data for 25 ns-1064 nm laser pulses. This model is then coupled with a previously developed thermal model for LSP to calculate the pressure pulse induced on the target surface. The trend of the pressure saturation and the pressure pulse duration decrease beyond some threshold laser irradiance is captured successfully by the model, and good agreements with experimental data have been obtained under a variety of LSP conditions.

  2. Signal loss of double transmissions of ultrasonic waves through random rough surfaces.

    PubMed

    Chen, Ziqiang; Yang, Lin

    2011-01-01

    This paper establishes a model evaluating the signal loss of double transmitted acoustic beams through random rough liquid-solid surfaces based on Fresnel approximation and the phase-screen approximation. The numerical solution is replaced with a simple analytical solution through using the exponential substitution approach to remove the nonlinear integral terms. Therefore, the real-time inspection by using C-scan imaging systems of flaws in materials can be achieved through the proposed model. The research results show that the signal loss of double transmissions from random rough surfaces mainly depends on two factors: the root-mean-square (RMS) of the roughness and the depth of the flaw in materials. The experimentally measured signal loss is in good agreement with the theoretical predictions. The evaluation of the signal loss can be useful for improving the accuracy and reliability of the non-destructive testing (NDT). PMID:20561660

  3. A long-pulse repetitive operation magnetically insulated transmission line oscillator.

    PubMed

    Fan, Yu-Wei; Zhong, Hui-Huang; Zhang, Jian-De; Shu, Ting; Liu, Jin Liang

    2014-05-01

    The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO. PMID:24880374

  4. A long-pulse repetitive operation magnetically insulated transmission line oscillator

    NASA Astrophysics Data System (ADS)

    Fan, Yu-Wei; Zhong, Hui-Huang; Zhang, Jian-De; Shu, Ting; Liu, Jin Liang

    2014-05-01

    The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO.

  5. A long-pulse repetitive operation magnetically insulated transmission line oscillator

    SciTech Connect

    Fan, Yu-Wei; Zhong, Hui-Huang; Zhang, Jian-De; Shu, Ting; Liu, Jin Liang [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-05-15

    The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO.

  6. Pulse position modulation for a subcarrier-multiplexed optical fiber transmission system

    NASA Astrophysics Data System (ADS)

    Wickramasinghe, V. R.; Ghassemlooy, Zabih F.

    1996-11-01

    Subcarrier multiplexed (SCM) optical network s offer a near to medium term alternative solution over high cost, evolving digital technology to distribute broadband services. Majority of existing systems are based on analogue optical transmission techniques and their principle disadvantage is the sensitivity to noise and system nonlinearities. Therefore, conventional SCM systems impose stringent noise and linearity requirements and as a result their performance is limited. A simple and attractive solution is to introduce an appropriate second stage modulator in order to improve the receiver sensitivity, hence the system performance.In this paper a SCM optical transmission system employing pulse position modulation as a second stage modulator, for transmission of video, audio and data channels is reported. Signal to noise ratio measurements obtained shows an improvement in optical receiver sensitivity compared with standard SCM systems.

  7. Ultrasonic meters measure gas pipeline flow

    SciTech Connect

    NONE

    1995-04-01

    New ultrasonic meters from Stork Ultrasonic Technologies, Houston are improving pipeline gas flow measurements, custody transfers, process gas flow measurements, and flare gas applications. The meters are easy to install, extremely accurate, and all feature realtime measurements. This meter (Gassonic 400) is designed for use in 8-in. to 64-in. gas pipelines and features a dual transducer device which uses the absolute digital travel time method of pulse transmission. Wide band piezoceramic transducers are used in this bi-directional, single bounce system which includes pulse verification and high-speed electronic processing by a central processing unit. Measuring values of this meter are obtained by direct digital measurement of travel time of each individual ultrasonic pulse which covers a pre-determined distance between two transducers inserted in the pipe wall. These transducers cause negligible flow restriction and absolute digital reference and excellent repeatability is possible without adjustment or re-calibration. Dozens of measurements can be processed so that average output values are updated every second during use. It is a field-programmable meter for variations in site parameters, presentation of service diagnostics, user selected velocity or quantity outputs, and has standard analog and digital interfaces. Also, it is suitable for swirl measurement or compensation. Since it relies on a reflection method, the ultrasonic meter allows easy, one-sided insertion and it is suitable for hot-tapping. This instrument is especially useful in gas blending stations, compressor control, leak detection, salt dome storage applications, pipeline balancing, and additive injection systems.

  8. Modeling the effects of beam size and flaw morphology on ultrasonic pulse/echo sizing of delaminations in carbon composites

    NASA Astrophysics Data System (ADS)

    Margetan, Frank J.; Leckey, Cara A.; Barnard, Dan

    2013-01-01

    The size and shape of a delamination in a multi-layered structure can be estimated in various ways from an ultrasonic pulse/echo image. For example the -6dB contours of measured response provide one simple estimate of the boundary. More sophisticated approaches can be imagined where one adjusts the proposed boundary to bring measured and predicted UT images into optimal agreement. Such approaches require suitable models of the inspection process. In this paper we explore issues pertaining to model-based size estimation for delaminations in carbon fiber reinforced laminates. In particular we consider the influence on sizing when the delamination is non-planar or partially transmitting in certain regions. Two models for predicting broadband sonic time-domain responses are considered: (1) a fast "simple" model using paraxial beam expansions and Kirchhoff and phase-screen approximations; and (2) the more exact (but computationally intensive) 3D elastodynamic finite integration technique (EFIT). Model-to-model and model-to experiment comparisons are made for delaminations in uniaxial composite plates, and the simple model is then used to critique the -6dB rule for delamination sizing.

  9. Modeling the Effects of Beam Size and Flaw Morphology on Ultrasonic Pulse/Echo Sizing of Delaminations in Carbon Composites

    NASA Technical Reports Server (NTRS)

    Margetan, Frank J.; Leckey, Cara A.; Barnard, Dan

    2012-01-01

    The size and shape of a delamination in a multi-layered structure can be estimated in various ways from an ultrasonic pulse/echo image. For example the -6dB contours of measured response provide one simple estimate of the boundary. More sophisticated approaches can be imagined where one adjusts the proposed boundary to bring measured and predicted UT images into optimal agreement. Such approaches require suitable models of the inspection process. In this paper we explore issues pertaining to model-based size estimation for delaminations in carbon fiber reinforced laminates. In particular we consider the influence on sizing when the delamination is non-planar or partially transmitting in certain regions. Two models for predicting broadband sonic time-domain responses are considered: (1) a fast "simple" model using paraxial beam expansions and Kirchhoff and phase-screen approximations; and (2) the more exact (but computationally intensive) 3D elastodynamic finite integration technique (EFIT). Model-to-model and model-to experiment comparisons are made for delaminations in uniaxial composite plates, and the simple model is then used to critique the -6dB rule for delamination sizing.

  10. The effect of stress on ultrasonic pulses in fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Hemann, J. H.; Baaklini, G. Y.

    1983-01-01

    An acoustical-ultrasonic technique was used to demonstrate relationships existing between changes in attenuation of stress waves and tensile stress for an eight ply 0 degree graphite-epoxy fiber reinforced composite. All tests were conducted in the linear range of the material for which no mechanical or macroscopic damage was evident. Changes in attenuation were measured as a function of tensile stress in the frequency domain and in the time domain. Stress wave propagation in these specimens was dispersive, i.e., the wave speed depends on frequency. Wave speeds varied from 267 400 cm/sec to 680 000 cm/sec as the frequency of the signal was varied from 150 kHz to 1.9 MHz which strongly suggests that flexural/lamb wave modes of propagation exist. The magnitude of the attenuation changes depended strongly on tensile stress. It was further observed that the wave speeds increased slightly for all tested frequencies as the stress was increased.

  11. Inferring bread doneness with air-pulse/ultrasonic ranging measurements of the loaf elastic response

    NASA Astrophysics Data System (ADS)

    Faeth, Loren Elbert

    This research marks the discovery of a method by which bread doneness may be determined based on the elastic properties of the loaf as it bakes. The purpose of the study was to determine if changes in bread characteristics could be determined by non-contact methods during baking, as the basis for improved control of the baking process. Current control of the baking process is based on temperature and dwell time, which are determined by experience to produce a produce which is approximately ``done.'' There is no direct measurement of the property of interest, doneness. An ultrasonic measurement system was developed to measure the response of the loaf to an external stimulus. ``Doneness,'' as reflected in the internal elastic consistency of the bakery product, is assessed in less than 1/2 second, and requires no closer approach to the moving bakery product than about 2 inches. The system is designed to be compatible with strapped bread pans in a standard traveling-tray commercial oven.

  12. Simple Laser-Ultrasonic System Using a Single-Frequency Pulsed Laser Oscillator

    NASA Astrophysics Data System (ADS)

    Blouin, A.; Carrion, L.; Padioleau, C.; Bouchard, P.; Monchalin, J.-P.

    2005-04-01

    We present a new pulsed laser oscillator and system for the optical detection of ultrasound in materials using a flashlamp-pumped dual Nd:YAG rod configuration. A single-frequency laser oscillator based on one rod inside a ring cavity is proposed. The second rod can be used as an amplifier for the oscillator or as a generation laser. Performance of the system is investigated with a two-wave mixing phase demodulator. Tests on metallic samples are presented.

  13. Ultrasonic flow measurements for irrigation process monitoring

    NASA Astrophysics Data System (ADS)

    Ziani, Elmostafa; Bennouna, Mustapha; Boissier, Raymond

    2004-02-01

    This paper presents the state of the art of the general principle of liquid flow measurements by ultrasonic method, and problems of flow measurements. We present an ultrasonic flowmeter designed according to smart sensors concept, for the measurement of irrigation water flowing through pipelines or open channels, using the ultrasonic transit time approach. The new flowmeter works on the principle of measuring time delay differences between sound pulses transmitted upstream and downstream in the flowing liquid. The speed of sound in the flowing medium is eliminated as a variable because the flowrate calculations are based on the reciprocals of the transmission times. The transit time difference is digitally measured by means of a suitable, microprocessor controlled logic. This type of ultrasonic flowmeter will be widely used in industry and water management, it is well studied in this work, followed by some experimental results. For pressurized channels, we use one pair of ultrasonic transducer arranged in proper positions and directions of the pipe, in this case, to determine the liquid velocity, a real time on-line analysis taking account the geometries of the hydraulic system, is applied to the obtained ultrasonic data. In the open channels, we use a single or two pairs of ultrasonic emitter-receiver according to the desired performances. Finally, the goals of this work consist in integrating the smart sensor into irrigation systems monitoring in order to evaluate potential advantages and demonstrate their performance, on the other hand, to understand and use ultrasonic approach for determining flow characteristics and improving flow measurements by reducing errors caused by disturbances of the flow profiles.

  14. Ballistic-Phonon-Pulse Transmission through a Solid-Liquid He II Interface at T=0.25 K

    Microsoft Academic Search

    H. W. M. Salemink; H. van Kempen; P. Wyder

    1978-01-01

    The transmission of ballistic longitudinal (L) and transverse (T) phonon pulses from sapphire to liquid He II at temperatures of T=0.25 K has been measured as a function of the pulse power and He II hydrostatic pressure for the first time. Under these experimental conditions, the converted L- and T-mode pulses propagate ballistically through He II. The results indicate that

  15. Direct optoelectronic generation and detection of sub-ps-electrical pulses on sub-mm-coaxial transmission lines

    E-print Network

    transmission line, using a new method for which the photoconductive material is brought into physical contactDirect optoelectronic generation and detection of sub-ps-electrical pulses on sub-mm-coaxial transmission lines Tae-In Jeona) and D. Grischkowskyb) School of Electrical and Computer Engineering, Oklahoma

  16. Pulse compression technique for simultaneous HIFU surgery and ultrasonic imaging: A preliminary study

    PubMed Central

    Jeong, Jong Seob; Chang, Jin Ho; Shung, K. Kirk

    2013-01-01

    In an ultrasound image-guided High Intensity Focused Ultrasound (HIFU) surgery, reflected HIFU waves received by an imaging transducer should be suppressed for real-time simultaneous imaging and therapy. In this paper, we investigate the feasibility of pulse compression scheme combined with notch filtering in order to minimize these HIFU interference signals. A chirp signal modulated by the Dolph-Chebyshev window with 3–9 MHz frequency sweep range is used for B-mode imaging and 4 MHz continuous wave is used for HIFU. The second order infinite impulse response notch filters are employed to suppress reflected HIFU waves whose center frequencies are 4 MHz and 8 MHz. The prototype integrated HIFU/imaging transducer that composed of three rectangular elements with a spherically con-focused aperture was fabricated. The center element has the ability to transmit and receive 6 MHz imaging signals and two outer elements are only used for transmitting 4 MHz continuous HIFU wave. When the chirp signal and 4 MHz HIFU wave are simultaneously transmitted to the target, the reflected chirp signals mixed with 4 MHz and 8 MHz HIFU waves are detected by the imaging transducer. After the application of notch filtering with pulse compression process, HIFU interference waves in this mixed signal are significantly reduced while maintaining original imaging signal. In the single scanline test using a strong reflector, the amplitude of the reflected HIFU wave is reduced to ?45 dB. In vitro test, with a sliced porcine muscle shows that the speckle pattern of the restored B-mode image is close to that of the original image. These preliminary results demonstrate the potential for the pulse compression scheme with notch filtering to achieve real-time ultrasound image-guided HIFU surgery. PMID:22356771

  17. Phase and group velocity measurement of ultrasonic guided wavetrains in plates by pulsed TV holography.

    PubMed

    Deán-Ben, X Luís; Trillo, Cristina; Doval, Angel F; Fernández, José L

    2010-04-01

    A method for the measurement of the phase and group velocities of guided acoustic waves is presented. For this purpose, a unique capability of a self-developed double-pulsed TV holography system to create movies of the propagation of guided acoustic wavetrains is used. Thereby, the experimental visualization of the evolution of Lamb and Rayleigh wavetrains in aluminum plates is shown, including several movies that illustrate different dispersive behaviors. Each movie shows the propagation of a narrowband wavetrain with a central frequency in the order of 1 MHz that consists of a carrier moving with the phase velocity, modulated by an envelope moving with the group velocity. Each snapshot is a two-dimensional map of the instantaneous out-of-plane displacement field of the surface points of the plate, with amplitudes in the order of several nanometers, acquired with the double-pulsed TV holography system. Then, by repeating the acquisition with successively increasing delays between the generation and detection instants, a sequence of maps is obtained from which a movie is composed. The phase and group velocities of the waves are accurately measured from the movies, yielding values that match well with the reference values for the same plates obtained from independent measurements. PMID:20370002

  18. Measurement of internal diameter changes and pulse wave velocity in fetal descending aorta using the ultrasonic phased-tracking method in normal and growth-restricted fetuses.

    PubMed

    Miyashita, Susumu; Murotsuki, Jun; Muromoto, Jin; Ozawa, Katsusuke; Yaegashi, Nobuo; Hasegawa, Hideyuki; Kanai, Hiroshi

    2015-05-01

    Phased tracking (PT) is an ultrasound-based technique that enables precise measurement of a target velocity. The aims of this study were to use PT to evaluate arterial pulse waveform, pulse wave velocity and fetal pulse pressure in normal and growth-restricted fetuses. One hundred fetuses with normal development and 15 fetuses with growth restriction were analyzed. Ultrasonic raw radiofrequency signals were captured from a direction perpendicular to the vascular axis at the fetal diaphragmatic level for the difference in internal dimensions (DID), or simultaneously from different directions for the pulse wave velocity. Pulsatile movement of the proximal and distal intima of the vessels was analyzed using PT. The fetal DID exhibited no significant changes in growth-restricted fetuses. Pulse wave velocity (3.8 ± 0.32 m/s vs. 2.2 ± 0.069 m/s, p < 0.001) and estimated pulse pressure (6.9 ± 0.90 kPa vs. 2.5 ± 0.18 kPa, p < 0.001) were significantly elevated in growth-restricted fetuses. Assessment of DID and pulse wave velocity of the descending aorta using PT is a feasible, non-invasive approach to evaluation of fetal hemodynamics. PMID:25727918

  19. Application of Laser-Ultrasonics to the Non-Contact, Pulse Echo Measurement of the Thickness of Micron Thin Metallic Coatings

    NASA Astrophysics Data System (ADS)

    Nadeau, A.; Martin, F.; Blouin, A.; Nadeau, F.; Choquet, M.; Lord, M.

    2007-03-01

    The general scope of this work was to use recently available ultra-short pulsed lasers to perform laser-ultrasonic pulse-echo thicknesses measurements on thin electroplated metallic coatings. Experiments were first performed using a femtosecond laser coupled to a confocal Fabry-Perot interferometer (CFPI). The results showed that the CFPI is often inappropriate for the detection of ultrasound pulses having spectral widths much larger than the interferometer's free spectral range. A second experimental session was conducted using a picosecond laser and an InPFe photorefractive interferometer. Multiple echoes of broad band compression waves (up to 500 MHz) were successfully detected on electrodeposited metallic coatings of zinc on steel substrates for thicknesses from 30 to 100 microns. The results show very little dispersion and attenuation in the zinc coatings.

  20. A comparison of traditional and emerging ultrasonic methods for the nondestructive evaluation of polymer matrix composites subjected to impact damage

    Microsoft Academic Search

    Richard E. Martin; Donald J. Roth; Charles G. Pergantis; Jaswinder S. Sandhu

    2004-01-01

    This paper presents the results of a comparison study of three ultrasonic nondestructive evaluation (NDE) methods applied to polymer matrix composite (PMC) specimens subjected to impact damage. Samples mainly consisted of various thicknesses of graphite\\/epoxy coupon panels impacted with various energy levels. Traditional pulse-echo and through transmission ultrasonic c-scan techniques were applied to impacted samples and served as the basis

  1. Detection of structural damage from the local temporal coherence of diffuse ultrasonic signals

    Microsoft Academic Search

    Jennifer E. Michaels; Thomas E. Michaels

    2005-01-01

    Permanently mounted ultrasonic transducers have the potential to interrogate large areas of a structure, and thus be effective global sensors for structural health monitoring. Recorded signals, although very sensitive to damage, are long, complex, and difficult to interpret compared to pulse echo and through transmission signals customary for nondestructive testing. These diffuse signals also are quite sensitive to environmental effects

  2. Ultrasonic pulse detection with split spectrum processing and consecutive polarity coincidence

    SciTech Connect

    Ericsson, L.; Stepinski, T. [Uppsala Univ. (Sweden); Dahlgren, S. [ABB TRC, Taeby (Sweden)

    1995-08-01

    The subject of signal processing for material noise reduction has been addressed in a large number of papers during the last decade. Several processing algorithms have been proposed, of which the Split Spectrum Processing (SSP) probably is the most renowned. The SSP technique is based on a synthetic frequency diversity approach, i.e. a filter bank is applied in order to obtain a set of signals with decorrelated noise components. Provided that the target echoes meet certain requirements, they will remain correlated in the generated set of signals. Target echo extraction may then be implemented using a suitable correlation measure. Simple target extractors such as Polarity Thresholding and Amplitude Minimization have been suggested and proven successful if the processing parameters had been correctly tuned. However, parameter tuning is not a trivial matter and relevant echoes may be lost due to the parameter sensitivity. In the paper a new target extraction algorithm, which avoids the requirement for a priori knowledge of frequency range, is introduced. The algorithm, referred to as Consecutive Polarity Coincidence, makes explicit use of the pulse characteristics of the target echo in order to implement local bandwidth estimation. If desired, a gating signal could be constructed by comparing the calculated bandwidth with a user defined threshold. Setting the threshold equal to the frequency range utilized for processing will generate a gating signal identical to the one obtained when using conventional Polarity Thresholding.

  3. System Performance Testing of the Pulse-Echo Ultrasonic Instrument for Critical Velocity Determination during Hanford Tank Waste Transfer Operations - 13584

    SciTech Connect

    Denslow, Kayte M.; Bontha, Jagannadha R.; Adkins, Harold E.; Jenks, Jeromy WJ; Hopkins, Derek F.; Thien, Michael G.; Kelly, Steven E.; Wooley, Theodore A.

    2013-06-01

    The delivery of Hanford double-shell tank waste to the Hanford Tank Waste Treatment and Immobilization Plant (WTP) is governed by specific Waste Acceptance Criteria that are identified in ICD 19 - Interface Control Document for Waste Feed. Waste must be certified as acceptable before it can be delivered to the WTP. The fluid transfer velocity at which solid particulate deposition occurs in waste slurry transport piping (critical velocity) is a key waste acceptance parameter that must be accurately characterized to determine if the waste is acceptable for transfer to the WTP. Washington River Protection Solutions and the Pacific Northwest National Laboratory have been evaluating the ultrasonic PulseEcho instrument since 2010 for its ability to detect particle settling and determine critical velocity in a horizontal slurry transport pipeline for slurries containing particles with a mean particle diameter of ?14 micrometers (?m). In 2012 the PulseEcho instrument was further evaluated under WRPS’ System Performance test campaign to identify critical velocities for slurries that are expected to be encountered during Hanford tank waste retrieval operations or bounding for tank waste feed. This three-year evaluation has demonstrated the ability of the ultrasonic PulseEcho instrument to detect the onset of critical velocity for a broad range of physical and rheological slurry properties that are likely encountered during the waste feed transfer operations between the Hanford tank farms and the WTP.

  4. System Performance Testing of the Pulse-Echo Ultrasonic Instrument for Critical Velocity Determination during Hanford Tank Waste Transfer Operations - 13584

    SciTech Connect

    Denslow, Kayte M.; Bontha, Jagannadha R.; Adkins, Harold E.; Jenks, Jeromy W.J.; Hopkins, Derek F. [Pacific Northwest National Laboratory, Richland, Washington 99354 (United States)] [Pacific Northwest National Laboratory, Richland, Washington 99354 (United States); Thien, Michael G.; Kelly, Steven E.; Wooley, Theodore A. [Washington River Protection Solutions, Richland, Washington 99354 (United States)] [Washington River Protection Solutions, Richland, Washington 99354 (United States)

    2013-07-01

    The delivery of Hanford double-shell tank waste to the Hanford Tank Waste Treatment and Immobilization Plant (WTP) is governed by specific Waste Acceptance Criteria that are identified in ICD 19 - Interface Control Document for Waste Feed. Waste must be certified as acceptable before it can be delivered to the WTP. The fluid transfer velocity at which solid particulate deposition occurs in waste slurry transport piping (critical velocity) is a key waste acceptance parameter that must be accurately characterized to determine if the waste is acceptable for transfer to the WTP. Washington River Protection Solutions and the Pacific Northwest National Laboratory have been evaluating the ultrasonic PulseEcho instrument since 2010 for its ability to detect particle settling and determine critical velocity in a horizontal slurry transport pipeline for slurries containing particles with a mean particle diameter of =14 micrometers (?m). In 2012 the PulseEcho instrument was further evaluated under WRPS' System Performance test campaign to identify critical velocities for slurries that are expected to be encountered during Hanford tank waste retrieval operations or bounding for tank waste feed. This three-year evaluation has demonstrated the ability of the ultrasonic PulseEcho instrument to detect the onset of critical velocity for a broad range of physical and rheological slurry properties that are likely encountered during the waste feed transfer operations between the Hanford tank farms and the WTP. (authors)

  5. A qualitative and quantitative investigation of the uncracked and cracked condition of concrete beams using impulse excitation, acoustic emission, and ultrasonic pulse velocity techniques

    NASA Astrophysics Data System (ADS)

    Iliopoulos, S.; Iliopoulos, A.; Pyl, L.; Sol, H.; Aggelis, D. G.

    2014-04-01

    The Impulse Excitation Technique (IET) is a useful tool for characterizing the structural condition of concrete. Processing the obtained dynamic parameters (damping ratio, response frequency) as a function of response amplitude, clear and systematic differences appear between intact and cracked specimens, while factors like age and sustained load are also influential. Simultaneously, Acoustic Emission (AE) and Ultrasonic Pulse Velocity (UPV) techniques are used during the three point bending test of the beams in order to supply additional information on the level of damage accumulation which resulted in the specific dynamic behavior revealed by the IET test.

  6. Magnetohydrodynamic electromagnetic pulse (MHD-EMP) interaction with power transmission and distribution systems

    SciTech Connect

    Tesche, F.M. [Tesche (F.M.), Dallas, TX (United States); Barnes, P.R. [Oak Ridge National Lab., TN (United States); Meliopoulos, A.P.S. [Georgia Inst. of Tech., Atlanta, GA (United States). Dept. of Electrical Engineering

    1992-02-01

    This report discusses the effects of the late-time high-altitude electromagnetic pulse (HEMP) on electrical transmission and distribution (T&D) systems. This environment, known as the magnetohydrodynamic electromagnetic pulse (MHD-EMP), is a very slowly varying electric field induced in the earth`s surface, similar to the field induced by a geomagnetic storm. It can result in the flow of a quasi-dc current in grounded power lines and in the subsequent magnetic saturation of transformers. This saturation, in turn, causes 6-Hz harmonic distortion and an increase in the reactive power required by generation facilities. This report analyzes and discusses these phenomena. The MHD-EMP environment is briefly discussed, and a simplified form of the earth-induced electric field is developed for use in a parametric study of transmission line responses. Various field coupling models are described, and calculated results for the responses of both transmission- and distribution-class power lines are presented. These calculated responses are compared with measurements of transformer operation under dc excitation to infer the MHD-EMP response of these power system components. It is found that the MHD-EMP environment would have a marked effect on a power system by inducing up to several hundreds of amperes of quasi-dc current on power lines. These currents will cause transformers to saturate which could result in excessive harmonic generation, voltage swings, and voltage suppression. The design of critical facilities which are required to operate during and after MHD-EMP events will have to be modified in order to mitigate the effects of these abnormal power system conditions.

  7. Magnetohydrodynamic electromagnetic pulse (MHD-EMP) interaction with power transmission and distribution systems

    SciTech Connect

    Tesche, F.M. (Tesche (F.M.), Dallas, TX (United States)); Barnes, P.R. (Oak Ridge National Lab., TN (United States)); Meliopoulos, A.P.S. (Georgia Inst. of Tech., Atlanta, GA (United States). Dept. of Electrical Engineering)

    1992-02-01

    This report discusses the effects of the late-time high-altitude electromagnetic pulse (HEMP) on electrical transmission and distribution (T D) systems. This environment, known as the magnetohydrodynamic electromagnetic pulse (MHD-EMP), is a very slowly varying electric field induced in the earth's surface, similar to the field induced by a geomagnetic storm. It can result in the flow of a quasi-dc current in grounded power lines and in the subsequent magnetic saturation of transformers. This saturation, in turn, causes 6-Hz harmonic distortion and an increase in the reactive power required by generation facilities. This report analyzes and discusses these phenomena. The MHD-EMP environment is briefly discussed, and a simplified form of the earth-induced electric field is developed for use in a parametric study of transmission line responses. Various field coupling models are described, and calculated results for the responses of both transmission- and distribution-class power lines are presented. These calculated responses are compared with measurements of transformer operation under dc excitation to infer the MHD-EMP response of these power system components. It is found that the MHD-EMP environment would have a marked effect on a power system by inducing up to several hundreds of amperes of quasi-dc current on power lines. These currents will cause transformers to saturate which could result in excessive harmonic generation, voltage swings, and voltage suppression. The design of critical facilities which are required to operate during and after MHD-EMP events will have to be modified in order to mitigate the effects of these abnormal power system conditions.

  8. Uplink transmission of a 60-km-reach WDM/OCDM-PON using a spectrum-sliced pulse source

    NASA Astrophysics Data System (ADS)

    Choi, Yong-Kyu; Hanawa, Masanori; Park, Chang-Soo

    2014-02-01

    We propose and experimentally demonstrate the uplink transmission of a 60-km-reach wavelength division multiplexing/optical code division multiplexing (WDM/OCDM) passive optical network (PON) using a spectrum-sliced pulse source. As a single light source, a broadband pulse source with a bandwidth of 6.5 nm and a repetition rate of 1.25 GHz is generated at a central office and supplied to a remote node (RN) through a 50-km fiber link. At the RN, narrow-band pulses (as a source for uplink transmission) are obtained by spectrum slicing the broadband pulse source with a cyclic arrayed waveguide grating and are then supplied to all optical network units (ONUs) via 1×4 power splitters and 10-km drop fibers. Eight wavelengths are obtained with a 6.5-nm bandwidth of the broadband pulse source, and the qualities of the pulses with a repetition rate of 1.25 GHz and a pulse width of 45 ps for the eight wavelengths are sufficient for four-chip OCDM encoding at the ONUs. In our experiments, four signals are multiplexed by OCDM at one wavelength, and another encoded signal is also multiplexed by WDM. The bit error rates (BERs) of the signals exhibit error-free transmission (BER<10-9) over a 60-km single-mode fiber at 1.25 Gb/s.

  9. Infrared transmission characteristic of indium-tin-oxide thin films prepared by femtosecond pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Zhu, Xubo; Sun, Weiguo; Tao, Fei; Cao, Xiancun; Zhang, Xiaolei

    2013-09-01

    Indium tin oxide (ITO) films were deposited on sapphire substrates at temperatures ranging from 30°C to 700°C and oxygen background pressure changing from 0.05 Pa to 0.25 Pa by femtosecond pulsed laser deposition (PLD). The films were characterized using metallurgical microscope, film resistance meter and Fourier transform infrared spectrometer to study the effect of substrate temperature and oxygen background pressure on the surface topography, sheet resistance and infrared transmission. The photographs of metallurgical microscope show that substrate temperature plays a dominant role on the surface morphology of the films. The sheet resistance test suggests that the sheet resistance of the film decreases with increase of substrate temperature but increases with increase of oxygen background pressure. The results of infrared transmission show that the infrared transmission through the ITO film is about 40% at the wavelength of 1.5?m to 1.8?m and is very low at other infrared band. The films deposited at higher substrate temperatures show lower value of transmittance, and which at higher oxygen background pressure show higher value of transmittance.

  10. Broadband method for measuring the ultrasonic absorption spectrum of biological tissues.

    PubMed

    Kaatze, U; Scholle, F D

    1990-09-01

    An apparatus is described which in the frequency range from about 5 to 500 MHz allows the ultrasonic absorption coefficient of biological tissues to be measured with 1% accuracy. This apparatus is based on a pulse transmission method in which a computer-controlled mode of operation is combined with a RF substitution technique. Superheterodyne detection of the transmitted signal, multiple data recording and signal averaging result in a high sensitivity of the measuring method. The apparatus can be also used to analyze the ultrasonic pulse reflected by the sample. PMID:2223939

  11. Experimental investigation on the nonlinear tolerance of root M-shaped pulse in spectrally efficient coherent transmissions.

    PubMed

    Xu, Xian; Zhuge, Qunbi; Châtelain, Benoît; Chagnon, Mathieu; Morsy-Osman, Mohamed; Malekiha, Mahdi; Qiu, Meng; Gao, Yuliang; Wang, Wei; Plant, David V

    2015-01-26

    We experimentally demonstrate improved intra-channel nonlinearity tolerance of the root M-shaped pulse (RMP) with respect to the root raised cosine (RRC) pulse in spectrally efficient 128 Gbit/s PDM-16QAM coherent transmission systems. In addition we evaluate the impact of dispersion map and fiber dispersion parameter on the intra-channel nonlinearity tolerance of the RRC pulse and the RMP via both simulation and experimentation. The RMP is shown to have a better nonlinear tolerance than the RRC pulse for most investigated scenarios except for links with zero residual dispersion percentage per span or the zero dispersion region of a fiber. Therefore, the RMP is suitable for extending the maximum reach of spectrally efficient coherent transmission systems in legacy links in addition to currently intensively studied standard single mode fiber (SSMF) based dispersion unmanaged links. PMID:25835848

  12. Long-distance pulse propagation on high-frequency dissipative nonlinear transmission lines\\/resonant tunneling diode line cascaded maps

    Microsoft Academic Search

    Yerima Klofaï; B. Z. Essimbi; D. Jäger

    2011-01-01

    Pulse propagation on high-frequency dissipative nonlinear transmission lines (NLTLs)\\/resonant tunneling diode line cascaded maps is investigated for long-distance propagation of short pulses. Applying perturbative analysis, we show that the dynamics of each line is reduced to an expanded Korteweg-de Vries-Burgers equation. Moreover, it is found by computer experiments that the soliton developed in NLTLs experiences an exponential amplitude decay on

  13. Ultrasonic Monitor

    NASA Technical Reports Server (NTRS)

    1983-01-01

    MicroUltrasonics PLR-1000 is a refined microprocessor-controlled version (usable on bolts, plates, liquids and gases) of the P2L2 developed by Langley Research Center. New technique is for nondestructive measurement of residual stress in various types of structures, for example, nuclear pressure vessels, pipes in nuclear reactors, offshore platforms, bridges, railroad tracks and wheels, aircraft wings, and engines. The instrument produces sound tone pulses that travel through a test specimen. PLR-1000 precisely measures speeds as stress increases speed of sound, tone changes, making precise measurements possible.

  14. Monitoring the early-age hydration of self-compacting concrete using ultrasonic p-wave transmission and isothermal calorimetry

    Microsoft Academic Search

    Bram DesmetKelly; Kelly Chrysanthe Atitung; Miguel Angel Abril Sanchez; John Vantomme; Dimitri Feys; Nicolas Robeyst; Katrien Audenaert; Geert De Schutter; Veerle Boel; Gert Heirman; Özlem Cizer; Lucie Vandewalle; Dionys Van Gemert

    The early-age hydration (?48 h) of a series of self-compacting concretes and corresponding mortars and one traditionally vibrated\\u000a concrete and mortar is monitored in a continuous way using ultrasonic testing and isothermal calorimetry. The mixtures differ\\u000a in type of mineral addition, superplasticizer, cement, cement-to-powder ratio and water-to-powder ratio. The influence of\\u000a these different mixture compositions on the kinetics of the hydration

  15. Novel high-frequency, high-power, pulsed oscillator based on a transmission line transformer.

    PubMed

    Burdt, R; Curry, R D

    2007-07-01

    Recent analysis and experiments have demonstrated the potential for transmission line transformers to be employed as compact, high-frequency, high-power, pulsed oscillators with variable rise time, high output impedance, and high operating efficiency. A prototype system was fabricated and tested that generates a damped sinusoidal wave form at a center frequency of 4 MHz into a 200 Omega load, with operating efficiency above 90% and peak power on the order of 10 MW. The initial rise time of the pulse is variable and two experiments were conducted to demonstrate initial rise times of 12 and 3 ns, corresponding to a spectral content from 4-30 and from 4-100 MHz, respectively. A SPICE model has been developed to accurately predict the circuit behavior and scaling laws have been identified to allow for circuit design at higher frequencies and higher peak power. The applications, circuit analysis, test stand, experimental results, circuit modeling, and design of future systems are all discussed. PMID:17672783

  16. Tailoring ultrasonic beams with optoacoustic holography

    Microsoft Academic Search

    Alex Meyer; Stefan J. Gspan; Stefan Bernet; Monika Ritsch-Marte

    2003-01-01

    A combination of laser-induced ultrasound generation and ultrasonic holography for spatial control of the generated ultrasonic pulse is presented. Ultrasound is produced by absorption of laser pulses at an absorbing layer in a water tank via the optoacoustic effect. In order to produce a defined ultrasonic frequency in the MHz range, the laser pulses are harmonically time-modulated using an acousto-optic

  17. Defect detection and size estimation in billet from profile of time-of-flight using ultrasonic transmission method with linear scanning

    NASA Astrophysics Data System (ADS)

    Miyamoto, Ryusuke; Mizutani, Koichi; Ebihara, Tadashi; Wakatsuki, Naoto

    2015-07-01

    In this study, defect detection and size estimation in billet by transmission method with linear scanning were carried out and the validity of the method was evaluated by numerical simulation. In addition, the suitable signal frequency and aperture of transducers were clarified. As a result, the following were found: a defect can be detected, signals with frequencies lower than those generally used in conventional ultrasonic testing (i.e., 0.5–1.5 MHz) are desirable, and the time-of-flight (TOF) deviation ?? becomes largest when the wavelength at center frequency and the aperture of transducers are comparable. Defect size can be estimated when a single defect exists alone and the defect is not near the surface of a billet. Although defect size estimation becomes difficult when the defect is near the surface of a billet, the defect can be detected by our proposed method.

  18. Infield CD uniformity control by altering transmission distribution of the photomask using ultra-fast pulsed laser technology

    Microsoft Academic Search

    Yasutaka Morikawa; Takanori Sutou; Yuichi Inazuki; Takashi Adachi; Yuuichi Yoshida; Kouichirou Kojima; Shiho Sasaki; Hiroshi Mohri; Naoya Hayashi; Vladimir Dmitriev; Sergey Oshemkov; Eitan Zait; Guy Ben-Zvi

    2006-01-01

    As pattern feature sizes on the wafer become smaller and smaller, requirements for CD variation control has become a critical issue. In order to correct CD uniformity on the wafer, the DUV light transmission distribution of the photomask was altered using an ultra-fast pulsed laser technology. By creating a small scattering pixel inside the quartz body of the mask, a

  19. A novel pulse echo correlation tester for transmission line fault location and identification using pseudorandom binary sequences

    Microsoft Academic Search

    Richard A. Guinee

    2008-01-01

    A novel pulse echo test methodology, using a pseudorandom binary sequence (PRBS) stimulus, is presented as a competitive alternative to Time Domain Reflectometry (TDR) for transmission line fault tracing and identification. The essential attribute of this scheme is the fault response cross correlation (CCR) with the PRBS test input which results in a unique identification signature for fault distance estimation

  20. Arctic acoustics ultrasonic modeling studies

    NASA Astrophysics Data System (ADS)

    Chamuel, Jacques R.

    1990-03-01

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

  1. Ultrasonic determination of recrystallization

    NASA Technical Reports Server (NTRS)

    Generazio, E. R.

    1986-01-01

    Ultrasonic attenuation was measured for cold worked Nickel 200 samples annealed at increasing temperatures. Localized dislocation density variations, crystalline order and colume percent of recrystallized phase were determined over the anneal temperature range using transmission electron microscopy, X-ray diffraction, and metallurgy. The exponent of the frequency dependence of the attenuation was found to be a key variable relating ultrasonic attenuation to the thermal kinetics of the recrystallization process. Identification of this key variable allows for the ultrasonic determination of onset, degree, and completion of recrystallization.

  2. Binary solvent extraction system and extraction time effects on phenolic antioxidants from kenaf seeds (Hibiscus cannabinus L.) extracted by a pulsed ultrasonic-assisted extraction.

    PubMed

    Wong, Yu Hua; Lau, Hwee Wen; Tan, Chin Ping; Long, Kamariah; Nyam, Kar Lin

    2014-01-01

    The aim of this study was to determine the best parameter for extracting phenolic-enriched kenaf (Hibiscus cannabinus L.) seeds by a pulsed ultrasonic-assisted extraction. The antioxidant activities of ultrasonic-assisted kenaf seed extracts (KSE) were determined by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay, ? -carotene bleaching inhibition assay, and ferric reducing antioxidant power (FRAP) assay. Total phenolic content (TPC) and total flavonoid content (TFC) evaluations were carried out to determine the phenolic and flavonoid contents in KSE. The KSE from the best extraction parameter was then subjected to high performance liquid chromatography (HPLC) to quantify the phenolic compounds. The optimised extraction condition employed 80% ethanol for 15?min, with the highest values determined for the DPPH, ABTS, and FRAP assay. KSE contained mainly tannic acid (2302.20?mg/100?g extract) and sinapic acid (1198.22?mg/100?g extract), which can be used as alternative antioxidants in the food industry. PMID:24592184

  3. Ultrasonic evaluation of high voltage circuit boards

    NASA Technical Reports Server (NTRS)

    Klima, S. J.; Riley, T. J.

    1976-01-01

    Preliminary observations indicate that an ultrasonic scanning technique may be useful as a quick, low cost, nondestructive method for judging the quality of circuit board materials for high voltage applications. Corona inception voltage tests were conducted on fiberglass-epoxy and fiberglass-polyimide high pressure laminates from 20 to 140 C. The same materials were scanned ultrasonically by utilizing the single transducer, through-transmission technique with reflector plate, and recording variations in ultrasonic energy transmitted through the board thickness. A direct relationship was observed between ultrasonic transmission level and corona inception voltage. The ultrasonic technique was subsequently used to aid selection of high quality circuit boards for the Communications Technology Satellite.

  4. Ringing in the pulse response of long and wideband coaxial transmission lines due to group delay dispersion

    SciTech Connect

    Kotzian,G.; de Maria,R.; Caspers, F.; Federmann, S.; Hofle, W.

    2009-05-04

    In particle accelerators coaxial cables are commonly used to transmit wideband beam signals covering many decades of frequencies over long distances. Those transmission lines often have a corrugated outer and/or inner conductor. This particular construction exhibits a significant amount of frequency dependent group delay variation. A comparison of simulations based on theoretical models, numerical simulations and S{sub 21} network analyzer measurements up to 2.5 GHz is presented. It is shown how the non-linear phase response and varying group delay leads to ringing in the pulse response and subsequent distortion of signal s transmitted through such coaxial transmission lines.

  5. Cross-phase modulation induced phase fluctuations in optical RZ pulse propagating in dispersion compensated WDM transmission systems

    NASA Astrophysics Data System (ADS)

    Faisal, Mohammad; Maruta, Akihiro

    2010-05-01

    The basic mechanism of cross-phase modulation induced phase fluctuations in optical RZ pulse propagating in a periodically dispersion compensated transmission line has been investigated. Ordinary differential equations have been derived using variational analysis to estimate the phase fluctuation and the analytical result is verified by numerical simulations based on split-step Fourier method. We therefore explore the impact of different dispersion compensation maps on phase fluctuation for 10 Gb/s and 40 Gb/s WDM transmission systems. The effects of initial pulse spacing between channels, channel spacing and residual dispersion on phase shift have been studied. We find that cross-phase modulation induced phase fluctuation can be mitigated by proper adjustment of channel spacing and/or residual dispersion.

  6. Use of Modified Transmission Line Models to reproduce Initial Breakdown Pulse Waveforms

    NASA Astrophysics Data System (ADS)

    Karunarathne, S.; Marshall, T. C.; Stolzenburg, M.; Karunarathna, N.

    2013-12-01

    E-change waveforms of Initial breakdown pulses (IBPs) were recorded at multiple sites in and around Kennedy Space center, Florida in summer of 2011. Locations of IBPs were obtained using TOA method and used as constraints to model six ';classic' IBPs using three modified transmission line (MTL) models (MTLL-linearly decaying current, MTLE-exponentially decaying current, MTLEI-exponentially increasing current) from the literature and a new model, MTLK, with the current following the Kumaraswamy distribution. All four models did a good job of modeling all six IBPs; the MTLE model was most often the best fit. It is important to note that for a given pulse, there is good agreement between the different models on a number of parameters: current risetime, current falltime, two current shape factors, current propagation speed, and the IBP charge moment change. Ranges and mean values of physical quantities found are: current risetime [4.8-25, (13×6)] ?s, current falltime [15-37, (25×6)] ?s, current speed [0.78-1.8, (1.3×0.3)]×10^8 m/s (excluding one extreme case of MTLEI), channel length [0.20-1.6, (0.6×0.3)] km, charge moment [0.015-0.30, (0.12×0.10)] C km, peak current [16-404, (80×80)] kA, and absolute average line charge density [0.11-4.7, (0.90×0.90)] mC/m. Currents in the MTLL and MTLE models deposit negative charge along their paths and the mean total charges deposited (Q) were -0.35 and -0.71 C. MTLEI currents effectively deposited positive charge along their paths with Q = 1.3 C. MTLK is more special regarding how it handles the charges. Initially, along the lower current path, negative charge is deposited and positive charge is deposited onto its upper path making the overall charge transfer almost zero, (Q = 3.8×10^-5 C). Because of this the MTLK model apparently obeys conservation of charge without making that a model constraint.

  7. Neutron resonance transmission spectroscopy with high spatial and energy resolution at the J-PARC pulsed neutron source

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; Shinohara, T.; Kai, T.; Ooi, M.; Kamiyama, T.; Kiyanagi, Y.; Shiota, Y.; McPhate, J. B.; Vallerga, J. V.; Siegmund, O. H. W.; Feller, W. B.

    2014-05-01

    The sharp variation of neutron attenuation at certain energies specific to particular nuclides (the lower range being from ~1 eV up to ~1 keV), can be exploited for the remote mapping of element and/or isotope distributions, as well as temperature probing, within relatively thick samples. Intense pulsed neutron beam-lines at spallation sources combined with a high spatial, high-timing resolution neutron counting detector, provide a unique opportunity to measure neutron transmission spectra through the time-of-flight technique. We present the results of experiments where spatially resolved neutron resonances were measured, at energies up to 50 keV. These experiments were performed with the intense flux low background NOBORU neutron beamline at the J-PARC neutron source and the high timing resolution (~20 ns at epithermal neutron energies) and spatial resolution (~55 ?m) neutron counting detector using microchannel plates coupled to a Timepix electronic readout. Simultaneous element-specific imaging was carried out for several materials, at a spatial resolution of ~150 ?m. The high timing resolution of our detector combined with the low background beamline, also enabled characterization of the neutron pulse itself - specifically its pulse width, which varies with neutron energy. The results of our measurements are in good agreement with the predicted results for the double pulse structure of the J-PARC facility, which provides two 100 ns-wide proton pulses separated by 600 ns, broadened by the neutron energy moderation process. Thermal neutron radiography can be conducted simultaneously with resonance transmission spectroscopy, and can reveal the internal structure of the samples. The transmission spectra measured in our experiments demonstrate the feasibility of mapping elemental distributions using this non-destructive technique, for those elements (and in certain cases, specific isotopes), which have resonance energies below a few keV, and with lower resolution for elements with relatively high resonance energies in the 1-30 keV range.

  8. Pulse-echo ultrasonic inspection system for in-situ nondestructive inspection of Space Shuttle RCC heat shields.

    SciTech Connect

    Roach, Dennis Patrick; Walkington, Phillip D.; Rackow, Kirk A.

    2005-06-01

    The reinforced carbon-carbon (RCC) heat shield components on the Space Shuttle's wings must withstand harsh atmospheric reentry environments where the wing leading edge can reach temperatures of 3,000 F. Potential damage includes impact damage, micro cracks, oxidation in the silicon carbide-to-carbon-carbon layers, and interlaminar disbonds. Since accumulated damage in the thick, carbon-carbon and silicon-carbide layers of the heat shields can lead to catastrophic failure of the Shuttle's heat protection system, it was essential for NASA to institute an accurate health monitoring program. NASA's goal was to obtain turnkey inspection systems that could certify the integrity of the Shuttle heat shields prior to each mission. Because of the possibility of damaging the heat shields during removal, the NDI devices must be deployed without removing the leading edge panels from the wing. Recently, NASA selected a multi-method approach for inspecting the wing leading edge which includes eddy current, thermography, and ultrasonics. The complementary superposition of these three inspection techniques produces a rigorous Orbiter certification process that can reliably detect the array of flaws expected in the Shuttle's heat shields. Sandia Labs produced an in-situ ultrasonic inspection method while NASA Langley developed the eddy current and thermographic techniques. An extensive validation process, including blind inspections monitored by NASA officials, demonstrated the ability of these inspection systems to meet the accuracy, sensitivity, and reliability requirements. This report presents the ultrasonic NDI development process and the final hardware configuration. The work included the use of flight hardware and scrap heat shield panels to discover and overcome the obstacles associated with damage detection in the RCC material. Optimum combinations of custom ultrasonic probes and data analyses were merged with the inspection procedures needed to properly survey the heat shield panels. System features were introduced to minimize the potential for human factors errors in identifying and locating the flaws. The in-situ NDI team completed the transfer of this technology to NASA and USA employees so that they can complete 'Return-to-Flight' certification inspections on all Shuttle Orbiters prior to each launch.

  9. Pulsed current wave shaping with a transmission line by utilizing superposition of a forward and a backward voltage wave for fast capillary Z-pinch discharge.

    PubMed

    Sakai, Y; Takahashi, S; Watanabe, M; Kim, G-H; Hotta, E

    2010-04-01

    By using a water transmission line, current wave shaping was demonstrated for a fast capillary Z-pinch discharge recombination soft x-ray laser study. The pulsed power system consists of a water capacitor, a gap switch, a transmission line, and a capillary plasma load. A voltage wave initiated at the water capacitor propagates toward the capillary load through the transmission line. Control of the pulse delay that occurred in the transmission line provides the superposition of the forward and the backward voltage waves effectively in order to perform current wave shaping with higher current amplitude and rapid current decay. PMID:20441338

  10. Ultrasonic Imaging Transceiver Design for CMUT: A Three-Level 30-Vpp Pulse-Shaping Pulser With Improved Efficiency and a Noise-Optimized Receiver

    E-print Network

    Chen, Kailiang

    This paper demonstrates a four-channel transceiver chip for medical ultrasonic imaging, interfacing to the capacitive micromachined ultrasonic transducers (CMUTs). The high-voltage transmitter (Tx) uses a three-level ...

  11. Comparison of X-Ray, Millimeter Wave, Shearography and Through-Transmission Ultrasonic Methods for Inspection of Honeycomb Composites

    NASA Astrophysics Data System (ADS)

    Abou-Khousa, M. A.; Ryley, A.; Kharkovsky, S.; Zoughi, R.; Daniels, D.; Kreitinger, N.; Steffes, G.

    2007-03-01

    Honeycomb composites are increasingly finding utility in a variety of environments and applications, such as aircraft structural components, flight control components, radomes, etc. In-service and environmental stresses can produce unwanted flaws that adversely affect the structural integrity and functionality of these composites. These flaws may be in the forms of disbonds, delaminations, impact damage, crushed honeycomb, moisture intrusion, internal cracks, etc. There are several nondestructive testing (NDT) methods that may be used to inspect these composites for the presence and evaluation of these flaws. Such NDT methods include X-ray computed tomography, near-field millimeter wave, shearography, and ultrasonic testing. To assess the capabilities of these methods for honeycomb composite inspection, two honeycomb composites panels were produced with several embedded flaws and missing material primarily representing planar disbonds at various levels within the thickness of the panels and with different shapes. Subsequently, the aforementioned NDT methods were used to produce images of the two panels. This paper presents the results of these investigations and a comparison among the capabilities of these methods.

  12. Fast Rise-Time Pulse Transformers Based on Transmission Line Transformer Like Structures

    Microsoft Academic Search

    K. KJain; P. W. Smith

    2005-01-01

    A new set of fast rise-time transformers based on transmission line transformer techniques (TLT's)1 are described. The transformers are wound using loosely coupled wire pairs rather than transmission lines in order to avoid high voltage cable failure problems experienced with commercial coaxial transmission lines commonly used in TLT's. Although the high frequency response, associated with conventional TLT's, is not quite

  13. In-field CD uniformity control by altering transmission distribution of the photomask using ultra-fast pulsed laser technology

    NASA Astrophysics Data System (ADS)

    Morikawa, Yasutaka; Sutou, Takanori; Inazuki, Yuichi; Adachi, Takashi; Yoshida, Yuuichi; Kojima, Kouichirou; Sasaki, Shiho; Mohri, Hiroshi; Hayashi, Naoya; Dmitriev, Vladimir; Oshemkov, Sergey; Zait, Eitan; Ben-Zvi, Guy

    2006-05-01

    As pattern feature sizes on the wafer become smaller and smaller, requirements for CD variation control has become a critical issue. In order to correct CD uniformity on the wafer, the DUV light transmission distribution of the photomask was altered using an ultra-fast pulsed laser technology. By creating a small scattering pixel inside the quartz body of the mask, a multitude of such points creates Shading Elements inside the quartz according to a predetermined CD variations distribution map. These Shading Elements reduce the dose of scanner's laser illumination onto the wafer per a local area. Thus by changing the local light intensity, inside the exposure field, to a required level during the photolithographic process the wafer CD is changed locally inside the field. This complete process of writing a multitude of Shading Elements inside the mask in order to control the light transmission and hence wafer level CD locally is called the CD Control (CDC) process. We have evaluated the tool utilizing Ultra fast laser pulses (CDC 101) for local transmission and CD controllability on the wafer. We used Binary and Att-PSM test masks and three kinds of test patterns to confirm the sensitivity of transmission and CD change by the attenuation levels of Shading Elements which is sequentially changed from 0% to 10%. We will compare the AIMS results to printed CD on wafer or simulation results, so that we can correlate the transmission change and CD change by the attenuation levels. This paper also reports the CD uniformity correction performances by using attenuation mapping method on Binary mask. We also cover how Shading Elements affect the phase and transmission on the Att-PSM.

  14. A New Model of Ultrasonic Imaging System Based on Plane Wave Transmission and Angular Spectrum Propagation Principle

    Microsoft Academic Search

    Hu Peng

    2007-01-01

    A kind of high frame rate (HFR) 2D and 3D imaging method based on array beams, which belong to limited diffraction beams family, was developed about several years ago. Because only one transmission is required to construct an image, this method can reach an ultra high frame rate. Compared with conventional delay-and-sum (dynamic focusing) method, the HFR system is simple

  15. Transmission zerocrossings

    E-print Network

    Chen, Sheng

    ELEC3028 Digital Transmission -- MODEM S Chen Revision of Lecture 2 . Pulse shaping Tx/Rx filter­o# factor, and required baseband transmission bandwidth B = fs 2 (1+ #) MODEM components pulse shaping Tx: modulator/demodulator 27 #12; ELEC3028 Digital Transmission -- MODEM S Chen QAM Modulator / Demodulator

  16. Methods of theoretical analysis and computer modeling of the shaping of electrical pulses by nonlinear transmission lines and lumped-element delay lines

    Microsoft Academic Search

    Miles M. Turner; Greg Branch; Paul W. Smith

    1991-01-01

    The mechanism by which high-power electrical pulses can be sharpened by propagation along nonlinear transmission lines and lumped-element delay lines is described with emphasis on the production of pulses with very fast leading or trailing edges. A survey of some of the mathematical techniques that have been applied to the propagation of electrical signals along nonlinear lines and ladder networks

  17. Transmission of 1064 nm laser radiation during ablation with an ultra-short pulse laser (USPL) system

    NASA Astrophysics Data System (ADS)

    Schelle, Florian; Meister, Jörg; Oehme, Bernd; Frentzen, Matthias

    2012-01-01

    During ablation of oral hard tissue with an USPL system a small amount of the incident laser power does not contribute to the ablation process and is being transmitted. Partial transmission of ultra-short laser pulses could potentially affect the dental pulp. The aim of this study was to assess the transmission during ablation and to deduce possible risks for the patient. The study was performed with an Nd:YVO4 laser, emitting pulses with a duration of 8 ps at a wavelength of 1064 nm. A repetition rate of 500 kHz and an average power of 9 W were chosen to achieve high ablation efficiency. A scanner system created square cavities with an edge length of 1 mm. Transmission during ablation of mammoth ivory and dentin slices with a thickness of 2 mm and 5 mm was measured with a power meter, placed directly beyond the samples. Effects on subjacent blood were observed by ablating specimens placed in contact to pork blood. In a separate measurement the temperature increase during ablation was monitored using an infrared camera. The influence of transmission was assessed by tuning down the laser to the corresponding power and then directly irradiating the blood. Transmission during ablation of 2 mm specimens was about 7.7% (ivory) and 9.6% (dentin) of the incident laser power. Ablation of specimens directly in contact to blood caused coagulation at longer irradiation times (t~18s). Direct irradiation of blood with the transmitted power provoked bubbling and smoke formation. Temperature measurements identified heat generation as the main reason for the observed coagulation.

  18. Ultrasonic monitoring of material processing using clad buffer rod sensors

    NASA Astrophysics Data System (ADS)

    Ramos Franca, Demartonne

    Ultrasonic sensors and techniques are developed for in-line monitoring of polymer extrusion, cleanliness of molten metals and liquid flow speed at elevated temperature. Pulse-echo mode is used for the first two processes, while the through-transmission mode is applied in the third one. The ultrasonic probe consists of high performance clad buffer rods with different dimensions to thermally isolate the commercial ultrasonic transducer from materials at high temperature. The clad buffer rods are made of steel, polymer and ceramic. Steel clad buffer rods are introduced for in-line monitoring of polymer extrusion processes. Owing to its superior performance in pulse-echo mode, for the first time such a probe is installed and performs ultrasonic monitoring in the die of a co-extrusion machine and in the barrel section of a twin-screw extruder. It can reveal a variety of information relevant to process parameters, such as polymer layer thickness, interface location and adhesion quality, stability, or polymer composition change. For the ultrasonic monitoring of polymer processes, probes with acoustic impedance that matches that of the processed polymer may offer certain advantages such as quantitative viscoelastic evaluation; thus high temperature polymer clad buffer rods, in particular PEEK, are developed. It is demonstrated that this new probe exhibits unique advantages for in-line monitoring of the cure of epoxies and polymer extrusion process. Long steel clad buffer rods with a spherical focus lens machined at the probing end are proposed for cleanliness evaluation of molten metals. The potential of this focusing probe is demonstrated by means of high-resolution imaging and particles detection in molten zinc at temperatures higher than 600°C, using a single probe operated at pulse-echo mode. A contrapropagating ultrasonic flowmeter employing steel clad buffer rods is devised to operate at high temperature. It is demonstrated that these rods guide ultrasonic signals whose velocity is dependent on the average temperature of the flow. Thus, a novel technique to significantly reduce the temperature effects of ultrasonic flowmeters is successfully developed and tested in motor oil flow at 130°C.

  19. Effective transformation of the energy of high-voltage pulses into high-frequency oscillations using a saturated-ferrite-loaded transmission line

    Microsoft Academic Search

    V. P. Gubanov; A. V. Gunin; O. B. Koval’chuk; V. O. Kutenkov; I. V. Romanchenko; V. V. Rostov

    2009-01-01

    A new method of converting a high-voltage video pulse into high-frequency oscillations using a nonlinear transmission line\\u000a with temporal dispersion has been studied. The dispersion was provided by pulsed magnetization reversal in a ferrite, which\\u000a was initially magnetized to saturation in an external magnetic field. For a 9-ns pulse, an average energy conversion efficiency\\u000a of about 10% was achieved. It

  20. High-voltage isolation transformer for sub-nanosecond rise time pulses constructed with annular parallel-strip transmission lines.

    PubMed

    Homma, Akira

    2011-07-01

    A novel annular parallel-strip transmission line was devised to construct high-voltage high-speed pulse isolation transformers. The transmission lines can easily realize stable high-voltage operation and good impedance matching between primary and secondary circuits. The time constant for the step response of the transformer was calculated by introducing a simple low-frequency equivalent circuit model. Results show that the relation between the time constant and low-cut-off frequency of the transformer conforms to the theory of the general first-order linear time-invariant system. Results also show that the test transformer composed of the new transmission lines can transmit about 600 ps rise time pulses across the dc potential difference of more than 150 kV with insertion loss of -2.5 dB. The measured effective time constant of 12 ns agreed exactly with the theoretically predicted value. For practical applications involving the delivery of synchronized trigger signals to a dc high-voltage electron gun station, the transformer described in this paper exhibited advantages over methods using fiber optic cables for the signal transfer system. This transformer has no jitter or breakdown problems that invariably occur in active circuit components. PMID:21806208

  1. Pulse

    MedlinePLUS

    ... resting for at least 10 minutes. Take the exercise heart rate while you are exercising. ... pulse rate can help determine if the patient's heart is pumping. ... exercise, the pulse rate gives information about your fitness ...

  2. Design of non-selective refocusing pulses with phase-free rotation axis by gradient ascent pulse engineering algorithm in parallel transmission at 7 T

    NASA Astrophysics Data System (ADS)

    Massire, Aurélien; Cloos, Martijn A.; Vignaud, Alexandre; Le Bihan, Denis; Amadon, Alexis; Boulant, Nicolas

    2013-05-01

    At ultra-high magnetic field (?7 T), B1 and ?B0 non-uniformities cause undesired inhomogeneities in image signal and contrast. Tailored radiofrequency pulses exploiting parallel transmission have been shown to mitigate these phenomena. However, the design of large flip angle excitations, a prerequisite for many clinical applications, remains challenging due the non-linearity of the Bloch equation. In this work, we explore the potential of gradient ascent pulse engineering to design non-selective spin-echo refocusing pulses that simultaneously mitigate severe B1 and ?B0 non-uniformities. The originality of the method lays in the optimization of the rotation matrices themselves as opposed to magnetization states. Consequently, the commonly used linear class of large tip angle approximation can be eliminated from the optimization procedure. This approach, combined with optimal control, provides additional degrees of freedom by relaxing the phase constraint on the rotation axis, and allows the derivative of the performance criterion to be found analytically. The method was experimentally validated on an 8-channel transmit array at 7 T, using a water phantom with B1 and ?B0 inhomogeneities similar to those encountered in the human brain. For the first time in MRI, the rotation matrix itself on every voxel was measured by using Quantum Process Tomography. The results are complemented with a series of spin-echo measurements comparing the proposed method against commonly used alternatives. Both experiments confirm very good performance, while simultaneously maintaining a low energy deposition and pulse duration compared to well-known adiabatic solutions.

  3. Controlled ultrasonic tissue erosion

    NASA Astrophysics Data System (ADS)

    Cain, Charles

    2003-04-01

    Controlled ultrasonic tissue erosion has many clinical applications, including the placement of very precise sharply defined perforations in biological interfaces and membranes with focused ultrasound. With carefully chosen acoustic parameters, tissue can be rapidly eroded away at a constant etching rate. The maximum erosion rate for minimal propagated energy is obtained by using very short high intensity pulses. The etching rate is higher with shorter pulse durations. For short pulses less than 10 cycles of the drive frequency, an optimum pulse repetition rate exists which maximizes the etching rate. Higher gas saturation in the surrounding medium reduces the etching rate and reduces the spatial sharpness of the holes produced. Most of the erosion appears to be produced in the first several cycles of the therapy pulse. For example, a series of short (about 3 cycles) focused pulses of 2100 W/cm2 (Isppa) at 788 kHz can erode a very well defined 2 mm diameter hole in a 1 mm thick sample of fresh pork atrial posterior wall in about 1 min at the optimum pulse repetition rate (about 18 kHz). Controlled ultrasonic tissue erosion may provide an effective image guided noninvasive tool in treatment of neonatal patients with hypoplastic left heart syndrome. Without the mixing of oxygenated blood across perforations placed in the atrial septum, these infants do not survive.

  4. Ultrasonic Imaging Of Deep Arteries

    NASA Technical Reports Server (NTRS)

    Rooney, James A.; Heyser, Richard C.; Lecroissette, Dennis H.

    1990-01-01

    Swept-frequency sound replaces pulsed sound. Ultrasonic medical instrument produces images of peripheral and coronary arteries with resolutions higher and at depths greater than attainable by previous ultrasonic systems. Time-delay-spectrometry imager includes scanning, image-processing, and displaying equipment. It sweeps in frequency from 0 to 10 MHz in 20 ms, pauses for 5 ms, and repeats sweep. Intended for use in noninvasive detection and measurement of atherosclerotic lesions.

  5. Continuous wave ultrasonic Doppler tomography

    PubMed Central

    Liang, Haidong-Dong; Tsui, Chun Sing Louis; Halliwell, Michael; Wells, Peter N. T.

    2011-01-01

    In continuous wave ultrasonic Doppler tomography (DT), the ultrasonic beam moves relative to the scanned object to acquire Doppler-shifted frequency spectra which correspond to cross-range projections of the scattering and reflecting structures within the object. The relative motion can be circular or linear. These data are then backprojected to reconstruct the two-dimensional image of the object cross section. By using coherent processing, the spatial resolution of ultrasonic DT is close to an order of magnitude better than that of traditional pulse-echo imaging at the same ultrasound frequency. PMID:22866236

  6. Quasi-monochromatic bound on ultrashort light-pulse transmission through fog.

    PubMed

    Shapiro, Jeffrey H

    2011-09-01

    The use of ultrashort (femtosecond duration) light pulses for line-of-sight free-space optical (FSO) communication through fog is receiving increasing attention. Assuming that the transmitter power is low enough to preclude nonlinear interactions, and that scattering-induced multipath spread is less than the reciprocal of the scattering-induced Doppler spread, it is shown that the average transmitter-to-receiver fractional energy transfer of an ultrafast FSO system cannot exceed that of a quasimonochromatic (nanosecond pulse duration) system operating at the optimum wavelength within the ultrafast system's spectrum. Thus, an ultrashort-pulse system is not a solution for high-data-rate FSO communication through fog, because, at best, it will reproduce on average the energy-transfer performance of a wavelength-optimized quasimonochromatic system. PMID:21886209

  7. Monitoring of freeze-thaw cycles in concrete using embedded sensors and ultrasonic imaging.

    PubMed

    Ranz, Javier; Aparicio, Sofía; Romero, Héctor; Casati, María Jesús; Molero, Miguel; González, Margarita

    2014-01-01

    This paper deals with the study of damage produced during freeze-thaw (F-T) cycles using two non-destructive measurement approaches-the first approach devoted to continuous monitoring using embedded sensors during the cycles, and the second one, performing ultrasonic imaging before and after the cycles. Both methodologies have been tested in two different types of concrete specimens, with and without air-entraining agents. Using the first measurement approach, the size and distribution of pores were estimated using a thermoporometrical model and continuous measurements of temperature and ultrasonic velocity along cycles. These estimates have been compared with the results obtained using mercury porosimetry testing. In the second approach, the damage due to F-T cycles has been evaluated by automated ultrasonic transmission and pulse-echo inspections made before and after the cycles. With these inspections the variations in the dimensions, velocity and attenuation caused by the accelerated F-T cycles were determined. PMID:24481231

  8. Monitoring of Freeze-Thaw Cycles in Concrete Using Embedded Sensors and Ultrasonic Imaging

    PubMed Central

    Ranz, Javier; Aparicio, Sofía; Romero, Héctor; Casati, María Jesús; Molero, Miguel; González, Margarita

    2014-01-01

    This paper deals with the study of damage produced during freeze-thaw (F-T) cycles using two non-destructive measurement approaches—the first approach devoted to continuous monitoring using embedded sensors during the cycles, and the second one, performing ultrasonic imaging before and after the cycles. Both methodologies have been tested in two different types of concrete specimens, with and without air-entraining agents. Using the first measurement approach, the size and distribution of pores were estimated using a thermoporometrical model and continuous measurements of temperature and ultrasonic velocity along cycles. These estimates have been compared with the results obtained using mercury porosimetry testing. In the second approach, the damage due to F-T cycles has been evaluated by automated ultrasonic transmission and pulse-echo inspections made before and after the cycles. With these inspections the variations in the dimensions, velocity and attenuation caused by the accelerated F-T cycles were determined. PMID:24481231

  9. SOLITONS AND OPTICAL FIBERS: Multiwavelength pulse transmission in an optical fibre — amplifier system

    NASA Astrophysics Data System (ADS)

    Panoiu, N.-C.; Mel'nikov, I. V.; Mihalache, D.; Etrich, C.; Lederer, F.

    2002-11-01

    The structure and dynamics of solitary waves created in the interaction of multiwavelength pulses in a single-mode optical fibre with amplification, filtering, and amplitude modulation is analysed. It is shown that there is a critical wavelength separation between channels above which wavelength-division multiplexing with solitons is feasible and that this separation increases with the number of channels.

  10. Fully dispersion-compensated 500 fs pulse transmission over 50 km single-mode fiber

    E-print Network

    Purdue University

    characteristics and trim the fiber length pre- cisely to match dispersion and minimize distortion. For example of fiber lengths. More importantly, the pulse is still broadened significantly (to 700 fs) be- cause precision in fiber lengths and increases the tolerance to variations in fiber dispersion. Previously, our

  11. Assessment of fetal scalp oxygen saturation determination in the sheep by transmission pulse oximetry

    Microsoft Academic Search

    Mark J. M. Nijland; Uday Shankar; Vijay Iyer; Michael G. Ross

    2000-01-01

    Objective: Electronic fetal heart rate monitoring has an unacceptable false-positive nonreassuring rate, which results in an excess of operative interventions. As a more objective measure of fetal oxygenation, fetal scalp pulse oximetry has been used to assess fetal blood oxygen saturation (SO2). The current devices use reflectance oximetry, which has inherent limitations. These include varying depths of signal penetration, variation

  12. Investigation of the temporal spread of an ultrashort light pulse on transmission through

    E-print Network

    Dainty, Chris

    light that is either not scat- tered 1the ballistic light2 or that has undergone rela- tively few pulse. The ballistic 1unscattered2 component is attenu- ated according to Beer's law, where I0 Universitaria, Circuito Exterior, A. P. 70-186, Mexico D. F. 04510, Mexico. F. E. W. Schmidt and J. C. Dainty

  13. Wire Crimp Connectors Verification using Ultrasonic Inspection

    NASA Technical Reports Server (NTRS)

    Cramer, K. Elliott; Perey, Daniel F.; Yost, William T.

    2007-01-01

    The development of a new ultrasonic measurement technique to quantitatively assess wire crimp connections is discussed. The amplitude change of a compressional ultrasonic wave propagating through the junction of a crimp connector and wire is shown to correlate with the results of a destructive pull test, which previously has been used to assess crimp wire junction quality. Various crimp junction pathologies (missing wire strands, incorrect wire gauge, incomplete wire insertion in connector) are ultrasonically tested, and their results are correlated with pull tests. Results show that the ultrasonic measurement technique consistently (as evidenced with pull-testing data) predicts good crimps when ultrasonic transmission is above a certain threshold amplitude level. A physics-based model, solved by finite element analysis, describes the compressional ultrasonic wave propagation through the junction during the crimping process. This model is in agreement within 6% of the ultrasonic measurements. A prototype instrument for applying the technique while wire crimps are installed is also presented.

  14. Effect of experimental conditions on acousto-ultrasonic reproducibility

    Microsoft Academic Search

    Andrew L. Gyekenyesi; Laura M. Harmon; Harold E. Kautz

    2002-01-01

    Acousto-ultrasonics (AU) is a nondestructive evaluation (NDE) technique that utilizes two ultrasonic transducers to interrogate the condition of a test specimen. The sending transducer introduces an ultrasonic pulse at a point on the surface of the specimen while a receiving transducer detects the signal after it has passed through the material. The aim of the method is to correlate certain

  15. Analysis of Ferroelectric-Based Nonlinear Transmission Lines for Pulse Shaping Devices

    Microsoft Academic Search

    A. K. Mikhailov; T. B. Samoilova

    2006-01-01

    Described in this paper is the generalized analysis of a possibility to realize nonlinear transmission line (NLTL) as a distributed line with nonlinear dielectric. The analysis is based on phenomenological description of ferroelectrics C-V characteristics. Results presented show that the use of ceramic paraelectrics in NLTLs provides rather effective compression of high voltage steps of subnanosecond duration

  16. Pulse position modulation for a subcarrier-multiplexed optical fiber transmission system

    Microsoft Academic Search

    V. R. Wickramasinghe; Zabih F. Ghassemlooy

    1996-01-01

    Subcarrier multiplexed (SCM) optical network s offer a near to medium term alternative solution over high cost, evolving digital technology to distribute broadband services. Majority of existing systems are based on analogue optical transmission techniques and their principle disadvantage is the sensitivity to noise and system nonlinearities. Therefore, conventional SCM systems impose stringent noise and linearity requirements and as a

  17. AN ULTRASONIC STRAIN GAUGE Mathias Kersemans1

    E-print Network

    Boyer, Edmond

    of the reflection characteristics of normal incidence pulsed waves in frequency domain provides the out strain measurement techniques, yielding good agreement. As the ultrasonic strain gauge provides all three-UBPS) method is shown in Figure 1a, in which the ultrasonic transducer is operated as both emitter and receiver

  18. Active Monitoring of a Fault with Seismogenic Potential Using an Ultrasonic Transmission at 1 km Deep in the Ezulwini Mine, South Africa

    NASA Astrophysics Data System (ADS)

    Kawakata, H.; Yoshimitsu, N.; Nakatani, M.; Philipp, J.; Naoi, M.; Ward, A.; Doi, I.; Masakale, T.; Durrheim, R. J.; Ribeiro, L.; Morema, S.; Ogasawara, H.

    2014-12-01

    Not only the stress state but also the elastic and inelastic properties of rocks around a target fault may be key information on seismogenic processes. Monitoring them may help us improve earthquake hazard assessment. In laboratory, elastic wave speed has been found to decrease prior to the main fracture (e.g., Lockner et al., 1977; Yoshimitsu et al., 2009). At the Ezulwini mine in South Africa, a fault with a high potential for mining-induced earthquakes with a relatively large magnitude (M ~2) was specified based on boring-core observation, tunnel wall observation, and mining plans. We started monitoring transmitted waves across the fault at about 1 km deep (Kawakata et al., 2011). We installed a piezoelectric transmitter as a wave source about 20 m away from the fault in the hanging wall. Three accelerometers of 3-component were installed along the acoustic beam from the transmitter; one in the hanging wall, and the other two in the footwall. Ultrasonic pulses were repeatedly transmitted, and the received waves were recorded at 400 ksps. Transmitted signals can be clearly recognized in stacked waveforms of all channels. In May 2012, increases in travel times (5-10 ms) from 2011 were observed for all the three stations. The common delay suggested that the decrease in wave speed was not localized at the fault. After that, there was a long strike in the mine, and the data were missed for about 100 days and 300 days due to the lack of maintenance of the monitoring system. By September 2013, when the data recording was resumed, travel times to the two receivers located after crossing the fault had increased greatly to ~60 ms, while that to the receiver before the fault increased only to 20 ms. Assuming that the thickness of the fault is 5 m, the difference in delay of 40 ms corresponds to a wave speed decrease of 8 %. We have not identified a relatively large event that might be associated with this change in travel times, but the event search is not completed.

  19. Design of broadband transmission quarter-wave plates for polarization control of isolated attosecond pulses

    NASA Astrophysics Data System (ADS)

    Chen, Shujing; Lin, Chengyou; Gao, Hua

    2015-07-01

    Using a standard Levenberg–Marquardt algorithm, broadband quarter-wave plates (QWPs) with bandwidth from 3 to 18 eV in the extreme ultraviolet (EUV) region were designed using aperiodic Mo/Si multilayers. By analyzing the design results of the Mo/Si multiayers with different bilayer numbers, we found that a Mo/Si multilayer with more bilayers can achieve broader phase control, but suffers from lower total throughput and a degree of circular polarization. In addition, the pulse broadenings caused by the group delay dispersions of the designed broadband QWPs were studied, and their layer distributions were investigated. The oscillating distribution of bilayer thickness in optimized multilayers was observed, which is considered to be the reason for forming the broadband phase control. Such broadband QWPs can be applied to generate a circularly polarized broadband EUV source, such as isolated attosecond pulse, directly from a linearly polarized source.

  20. A fully distributed heterostructure-barrier varactor nonlinear transmission-line frequency multiplier and pulse sharpener

    Microsoft Academic Search

    Ming Li; Kathiravan Krishnamurthi; Robert G. Harrison

    1998-01-01

    The discrete symmetric heterostructure-barrier varactor (HBV) was previously developed as an unbiased frequency-tripling device that needed no second-harmonic idler circuit. Other work investigated nonlinear transmission lines (NLTLs) employing discrete varactors attached to linear guiding structures. Fully distributed Schottky-varactor NLTLs were excessively lossy. This paper explores NLTLs based on fully distributed HBV structures. Using both a modified finite-difference time-domain method and

  1. Application of wavelet analysis in two-dimensional ultrasonic flaw detection

    Microsoft Academic Search

    Anjani R. Achanta; Vittal Rao

    2003-01-01

    Ultrasonic inspection uses sound waves of short wavelength and high frequency to detect flaws in materials. The pulse of ultrasonic energy that is reflected by a discontinuity such as a void, delamination, inclusion or any other type of imperfection is highlighted as flaw in the ultrasonic image. Usually an ultrasonic signal that is reflected from the material contains multiple interfering

  2. High-temperature and broadband immersion ultrasonic probes

    Microsoft Academic Search

    Yuu Ono; Makiko Kobayashi; O. Moisan; Cheng-Kuei Jen

    2006-01-01

    Immersion ultrasonic probes for measurements and imaging at high temperature are presented. The probes consist of sol-gel-sprayed thick films as piezoelectric ultrasonic transducers (UTs) directly deposited onto steel buffer rods. They operate in pulse-echo mode at temperatures up to 500degC. The operating ultrasonic frequency is between 5 MHz and 20 MHz, controlled by the film thickness. The ultrasonic thickness measurement

  3. Comparative study of pulse interactions in optical fiber transmission systems with different modulation formats.

    PubMed

    Sinkin, O; Zweck, J; Menyuk, C

    2001-09-24

    We compare nonlinear channel interactions in classical soliton, periodically-stationary dispersion-managed soliton (DMS), and chirped-return-to-zero (CRZ) systems. We studied multichannel systems with a single pulse in each channel and a more general case with multiple bit streams in each channel. First, we find that in classical soliton systems, the distortions are reversible, while in the DMS and CRZ systems they are not. Second, we find that the classical soliton system shows no increase in the degradation as the number of channels increases, while both the DMS and CRZ systems do show an increase in the degradation. PMID:19421305

  4. Comparative study of pulse interactions in optical fiber transmission systems with different modulation formats

    NASA Astrophysics Data System (ADS)

    Sinkin, Oleg; Zweck, John W.; Menyuk, Curtis R.

    2001-09-01

    We compare nonlinear channel interactions in classical soliton, periodically-stationary dispersion-managed soliton (DMS), and chirped-return-to-zero (CRZ) systems. We studied multichannel systems with a single pulse in each channel and a more general case with multiple bit streams in each channel. First, we find that in classical soliton systems, the distortions are reversible, while in the DMS and CRZ systems they are not. Second, we find that the classical soliton system shows no increase in the degradation as the number of channels increases, while both the DMS and CRZ systems do show an increase in the degradation.

  5. An ultrasonic sensor for distance measurement in automotive applications

    Microsoft Academic Search

    Alessio Carullo; Marco Parvis

    2001-01-01

    This paper describes an ultrasonic sensor that is able to measure the distance from the ground of selected points of a motor vehicle. The sensor is based on the measurement of the time of flight of an ultrasonic pulse, which is reflected by the ground. A constrained optimization technique is employed to obtain reflected pulses that are easily detectable by

  6. Long range transmission loss of broadband seismic pulses in the Arctic under ice-free conditions.

    PubMed

    Thode, Aaron; Kim, Katherine H; Greene, Charles R; Roth, Ethan

    2010-10-01

    In 2008 the Louis S. St-Laurent (LSSL) surveyed deep Arctic waters using a three-airgun seismic source. Signals from the seismic survey were detected between 400 km and 1300 km range on a directional autonomous acoustic recorder deployed in water 53 m deep off the Alaskan North Slope. Observations of received signal levels between 10-450 Hz versus LSSL range roughly fit a cylindrical transmission loss model plus 0.01 dB/km attenuation in deep ice-free waters, and fit previous empirical models in ice-covered waters. The transition between ice-free and ice-covered propagation conditions shifted 200 km closer to the recorder during the survey. PMID:20968323

  7. Atmospheric transmission coefficients for laser pulses with spectral widths of a few tenths of a nanometer over the wavelength region from 800 to 860 nanometers

    NASA Technical Reports Server (NTRS)

    Safren, H. G.

    1988-01-01

    Effective atmospheric transmission spectra were calculated from 800 to 860 nanometers for laser sources with spectral widths of a few tenths of a nanometer. In this spectral region, the atmospheric absorption lines (water lines) have linewidths of a few hundredths of a nanometer, so that the transmission coefficient for a relatively wide laser pulse must be computed by taking a weighted average over the pulse spectral width. Laser spectral widths of several tenths of a nanometer are shown to reduce the effective absorption by water lines to as little as 10 to 20 percent, even when the laser is centered on a line or overlaps several lines. Thus, the effect of absorption by atmospheric water lines may be greatly reduced for laser communication systems using laser diode array transmitters, for which the pulse spectral width may be a few tenths of a nanometer.

  8. System and technique for ultrasonic determination of degree of cooking

    DOEpatents

    Bond, Leonard J. (Richland, WA); Diaz, Aaron A. (W. Richland, WA); Judd, Kayte M. (Richland, WA); Pappas, Richard A. (Richland, WA); Cliff, William C. (Richland, WA); Pfund, David M. (Richland, WA); Morgen, Gerald P. (Kennewick, WA)

    2007-03-20

    A method and apparatus are described for determining the doneness of food during a cooking process. Ultrasonic signal are passed through the food during cooking. The change in transmission characteristics of the ultrasonic signal during the cooking process is measured to determine the point at which the food has been cooked to the proper level. In one aspect, a heated fluid cooks the food, and the transmission characteristics along a fluid-only ultrasonic path provides a reference for comparison with the transmission characteristics for a food-fluid ultrasonic path.

  9. Surfaces and thin films studied by picosecond ultrasonics

    SciTech Connect

    Maris, J.H.; Tauc, J.

    1992-05-01

    This research is the study of thin films and interfaces via the use of the picosecond ultrasonic technique. In these experiments ultrasonic waves are excited in a structure by means of a picosecond light pulse ( pump pulse''). The propagation of these waves is detected through the use of a probe light pulse that is time-delayed relative to the pump. This probe pulse measures the change {Delta}R(t) in the optical reflectivity of the structure that occurs because the ultrasonic wave changes the optical properties of the structure. This technique make possible the study of the attenuation and velocity of ultrasonic waves up to much higher frequencies than was previously possible (up to least 500 GHz). In addition, the excellent time-resolution of the method makes it possible to study nanostructures of linear dimensions down to 100 {Angstrom} or less by ultrasonic pulse-echo techniques. 25 refs.

  10. Transmission Mössbauer spectroscopy on pulsed-laser-deposited thick Fe and Ni-Zn ferrite films

    NASA Astrophysics Data System (ADS)

    Oliver, F. W.; Seifu, D.; Hoffman, E.; Chrisey, D. B.; Horwitz, J. S.; Dorsey, P. C.

    1999-11-01

    Mössbauer spectroscopy with 57Fe is used to characterize pulsed-laser-deposited (PLD) Ni0.6Zny-Fe2O4 films is demonstrated. Mössbauer spectra were recorded as a function of film thickness (3-16 ?m) for films deposited in background O2 pressures of 50 and 200 mTorr, and for a zinc concentration of y=0.72. A spectrum was also recorded for y=0.4 deposited in a background pressure of 200 mTorr. The site occupancy was determined for the tetrahedral (A) and octahedral (B) sites. Results obtained here show that the effect of increasing the Zn is to shift Fe(tet) to Fe(oct). When compared with previous Mössbauer measurements on the bulk NiZn ferrites, the ferrite films give spectra of similar quality with no visible evidence of clustering or multiple phases present. The same linewidth was found for a PLD processed Fe film and a Mössbauer standard 70-?m-thick ?-Fe enriched foil. The Fe film had a magnetic hyperfine field of 334 kOe and no evidence of the presence of any iron oxides. Good spectra may be obtained by selecting substrates with low mass and low atomic number. We were successful in obtaining measurable Mössbauer spectra for films deposited on 0.5-mm-thick MgO, sapphire, and alumina substrates whereas films deposited on Si, GaAs, and cubic zirconia substrates did not give good spectra.

  11. Tailoring ultrasonic beams with optoacoustic holography

    NASA Astrophysics Data System (ADS)

    Meyer, Alex; Gspan, Stefan J.; Bernet, Stefan; Ritsch-Marte, Monika

    2003-06-01

    A combination of laser-induced ultrasound generation and ultrasonic holography for spatial control of the generated ultrasonic pulse is presented. Ultrasound is produced by absorption of laser pulses at an absorbing layer in a water tank via the optoacoustic effect. In order to produce a defined ultrasonic frequency in the MHz range, the laser pulses are harmonically time-modulated using an acousto-optic modulator (AOM). Additionally, the laser intensity is spatially controlled. This is realized with a high resolution liquid crystal spatial light modulator (LCD). A computer generated pattern is displayed at the LCD and projected by the expanded laser beam to an absorptive layer in the water tank. As a result, the emitted ultrasonic wave emerges in a predetermined way, which is an acoustical analogue to the effect of a "diffractive optical element" in laser optics. The flexible method of optical ultrasound generation and diffractive steering promises new applications in medical and technical ultrasound diagnostics.

  12. Model-based estimation of thin multi-layered media using ultrasonic measurements.

    PubMed

    Hägglund, Fredrik; Martinsson, Jesper; Carlson, Johan E

    2009-08-01

    In ultrasonic measurement situations, when dealing with media of multi-layered structures consisting of 1 or more thin layers, analysis of the measured ultrasonic waveform can be difficult because of overlapping and reverberant echoes. Information from the individual layers is then difficult to extract because the individual echoes cannot be detected. In this study, we use a parametric layer model to analyze the multi-layered material in a system identification approach. The parameters of the model are connected to physical properties of the investigated material, e.g., the reflection coefficients, the time-of-flight, and the attenuation. The main advantage using this model is that the complexity of the model is connected to the number of layers rather than the number of observable echoes in the received ultrasonic waveform. A system of linear equations is presented, giving the opportunity to find the model for both pulse-echo and through-transmission measurements. A thorough effort is made on the parameter estimation and optimization algorithm. The model is validated with practical measurements on a 3-layered structure using both pulse-echo and through-transmission techniques. The 3-layered material consists of a thin embedded middle layer with the time-of-flight in that layer shorter than the emitted signal's time support, giving rise to overlapping echoes. Finally the relation between the model parameters and physical properties of the material is established. PMID:19686984

  13. Ultrasonic imaging of textured alumina

    NASA Technical Reports Server (NTRS)

    Stang, David B.; Salem, Jonathan A.; Generazio, Edward R.

    1989-01-01

    Ultrasonic images representing the bulk attenuation and velocity of a set of alumina samples were obtained by a pulse-echo contact scanning technique. The samples were taken from larger bodies that were chemically similar but were processed by extrusion or isostatic processing. The crack growth resistance and fracture toughness of the larger bodies were found to vary with processing method and test orientation. The results presented here demonstrate that differences in texture that contribute to variations in structural performance can be revealed by analytic ultrasonic techniques.

  14. Intra-channel Fiber Nonlinearity Mitigation Based on DBP in Single Channel and WDM Coherent Transmission Systems Using Different Pulse Shapes

    Microsoft Academic Search

    Fangzheng Zhang; Jian Wu; Yu Ji; Yan Li; Wei Li; Kun Xu; Jintong Lin

    We numerically investigate intra-channel fiber nonlinearity mitigation using single-span step size digital backward propagation (DBP) in 112 Gb\\/s polarization-division-multiplexed-quadrature-phase-shift-keying (PDM-QPSK) coherent optical transmission systems. The DBP performance in single channel and wavelength-division-multiplexed (WDM) systems using non-return-to-zero (NRZ) or 50% return-to-zero (RZ) pulses are analyzed and compared. Results show that, the DBP benefits the transmission system with improved Q-factor and enlarged

  15. Out-of-plane ultrasonic velocity measurement

    DOEpatents

    Hall, Maclin S. (Marietta, GA); Brodeur, Pierre H. (Smyrna, GA); Jackson, Theodore G. (Atlanta, GA)

    1998-01-01

    A method for improving the accuracy of measuring the velocity and time of flight of ultrasonic signals through moving web-like materials such as paper, paperboard and the like, includes a pair of ultrasonic transducers disposed on opposing sides of a moving web-like material. In order to provide acoustical coupling between the transducers and the web-like material, the transducers are disposed in fluid-filled wheels. Errors due to variances in the wheel thicknesses about their circumference which can affect time of flight measurements and ultimately the mechanical property being tested are compensated by averaging the ultrasonic signals for a predetermined number of revolutions. The invention further includes a method for compensating for errors resulting from the digitization of the ultrasonic signals. More particularly, the invention includes a method for eliminating errors known as trigger jitter inherent with digitizing oscilloscopes used to digitize the signals for manipulation by a digital computer. In particular, rather than cross-correlate ultrasonic signals taken during different sample periods as is known in the art in order to determine the time of flight of the ultrasonic signal through the moving web, a pulse echo box is provided to enable cross-correlation of predetermined transmitted ultrasonic signals with predetermined reflected ultrasonic or echo signals during the sample period. By cross-correlating ultrasonic signals in the same sample period, the error associated with trigger jitter is eliminated.

  16. Out-of-plane ultrasonic velocity measurement

    DOEpatents

    Hall, M.S.; Brodeur, P.H.; Jackson, T.G.

    1998-07-14

    A method for improving the accuracy of measuring the velocity and time of flight of ultrasonic signals through moving web-like materials such as paper, paperboard and the like, includes a pair of ultrasonic transducers disposed on opposing sides of a moving web-like material. In order to provide acoustical coupling between the transducers and the web-like material, the transducers are disposed in fluid-filled wheels. Errors due to variances in the wheel thicknesses about their circumference which can affect time of flight measurements and ultimately the mechanical property being tested are compensated by averaging the ultrasonic signals for a predetermined number of revolutions. The invention further includes a method for compensating for errors resulting from the digitization of the ultrasonic signals. More particularly, the invention includes a method for eliminating errors known as trigger jitter inherent with digitizing oscilloscopes used to digitize the signals for manipulation by a digital computer. In particular, rather than cross-correlate ultrasonic signals taken during different sample periods as is known in the art in order to determine the time of flight of the ultrasonic signal through the moving web, a pulse echo box is provided to enable cross-correlation of predetermined transmitted ultrasonic signals with predetermined reflected ultrasonic or echo signals during the sample period. By cross-correlating ultrasonic signals in the same sample period, the error associated with trigger jitter is eliminated. 20 figs.

  17. An Ultrasonic-Adaptive Beamforming Method and Its Application for Trans-skull Imaging of Certain Types of Head Injuries; Part I: Transmission Mode.

    PubMed

    Shapoori, Kiyanoosh; Sadler, Jeff; Wydra, Adrian; Malyarenko, Eugene V; Sinclair, Anthony N; Maev, Roman Gr

    2015-05-01

    A new adaptive beamforming algorithm for imaging via small-aperture 1-D ultrasonic-phased arrays through composite layered structures is reported. Such structures cause acoustic phase aberration and wave refraction at undulating interfaces and can lead to significant distortion of an ultrasonic field pattern produced by conventional beamforming techniques. This distortion takes the form of defocusing the ultrasonic field transmitted through the barrier and causes loss of resolution and overall degradation of image quality. To compensate for the phase aberration and the refractional effects, we developed and examined an adaptive beamforming algorithm for small-aperture linear-phased arrays. After accurately assessing the barrier's local geometry and sound speed, the method calculates a new timing scheme to refocus the distorted beam at its original location. As a tentative application, implementation of this method for trans-skull imaging of certain types of head injuries through human skull is discussed. Simulation and laboratory results of applying the method on skull-mimicking phantoms are presented. Correction of up to 2.5 cm focal point displacement at up to 10 cm depth under our skull phantom is demonstrated. Quantitative assessment of the method in a variety of temporal focusing scenarios is also reported. Overall temporal deviation on the order of a few nanoseconds was observed between the simulated and experimental results. The single-point adaptive focusing results demonstrate strong potential of our approach for diagnostic imaging through intact human skull. The algorithms were implemented on an ultrasound advanced open-platform controlling 64 active elements on a 128-element phased array. PMID:25423646

  18. Intra-channel Fiber Nonlinearity Mitigation Based on DBP in Single Channel and WDM Coherent Optical Transmission Systems Using Different Pulse Shapes

    NASA Astrophysics Data System (ADS)

    Zhang, Fangzheng; Li, Jian Wu Yan; Xu, Kun; Lin, Jintong

    2011-11-01

    We numerically investigate intra-channel fiber nonlinearity mitigation using single-span step size digital backward propagation (DBP) in 112 Gb/s polarization-division-multiplexed-quadrature-phase-shift-keying (PDM-QPSK) coherent optical transmission systems. The DBP performance in single channel and wavelength-division-multiplexed (WDM) systems using non-return-to-zero (NRZ) or 50% return-to-zero (RZ) pulses are analyzed and compared. Results show that, the DBP can benefit the transmission system with improved Q-factor and enlarged input optical power range. This improvement for WDM system is poorer than that for single channel system, and the DBP performs even worse in WDM system with narrower channel spacing. Further studies show that single-span step size DBP can bring more system improvement for NRZ-PDM-QPSK system than 50% RZ-PDM-QPSK system, although the 50% RZ pulse is more resistant to fiber nonlinearities.

  19. Graphene electrostatic microphone and ultrasonic radio.

    PubMed

    Zhou, Qin; Zheng, Jinglin; Onishi, Seita; Crommie, M F; Zettl, Alex K

    2015-07-21

    We present a graphene-based wideband microphone and a related ultrasonic radio that can be used for wireless communication. It is shown that graphene-based acoustic transmitters and receivers have a wide bandwidth, from the audible region (20?20 kHz) to the ultrasonic region (20 kHz to at least 0.5 MHz). Using the graphene-based components, we demonstrate efficient high-fidelity information transmission using an ultrasonic band centered at 0.3 MHz. The graphene-based microphone is also shown to be capable of directly receiving ultrasound signals generated by bats in the field, and the ultrasonic radio, coupled to electromagnetic (EM) radio, is shown to function as a high-accuracy rangefinder. The ultrasonic radio could serve as a useful addition to wireless communication technology where the propagation of EM waves is difficult. PMID:26150483

  20. Inexpensive Ultrasonic Interferometer

    NASA Astrophysics Data System (ADS)

    Grossmann, John; Svitelskiy, Oleksiy; Suslov, Alexey

    2013-03-01

    Growing interest of small universities and colleges in research determines an increasing need in affordable laboratory equipment that would be capable of producing scientifically valuable experimental results. In this report we present the current status of our efforts to develop a simple and low-cost version of a classical experimental setup for ultrasonic pulse-echo measurements that would be easily reproducible in the electronics shop of any small educational institution. In particular, usage of a dual timer microchip LM556 allowed us to simplify the design of a probing pulse generator. Also, we propose that using modern broadband RF components in phase detection circuits will allow us to substitute the complicated and expensive superheterodyne design of receiver with the technique of direct transformation and analysis of the echo signal right at the probe frequency. Our analysis shows that these simplifications can be achieved without compromising for sensitivity of the experiment or precision of measurements. Growing interest of small universities and colleges in research determines an increasing need in affordable laboratory equipment that would be capable of producing scientifically valuable experimental results. In this report we present the current status of our efforts to develop a simple and low-cost version of a classical experimental setup for ultrasonic pulse-echo measurements that would be easily reproducible in the electronics shop of any small educational institution. In particular, usage of a dual timer microchip LM556 allowed us to simplify the design of a probing pulse generator. Also, we propose that using modern broadband RF components in phase detection circuits will allow us to substitute the complicated and expensive superheterodyne design of receiver with the technique of direct transformation and analysis of the echo signal right at the probe frequency. Our analysis shows that these simplifications can be achieved without compromising for sensitivity of the experiment or precision of measurements. This work is supported by Research Council of Colgate University

  1. Pulse transformers

    Microsoft Academic Search

    H. Lord

    1971-01-01

    Pulse transformers capable of transmitting substantially rectangular voltage pulses, with durations of less than one microsecond, were developed for radar applications during World War II. Their primary functions were to match the impedances of high-power microwave radio-frequency electron-tube generators to electronic pulse generators and coaxial transmission cables, and to provide polarity reversal and impedance matching functions within pulse generator circuitry.

  2. Characterization of Heat Treated Titanium-Based Implants by Nondestructive Eddy Current and Ultrasonic Tests

    NASA Astrophysics Data System (ADS)

    Mutlu, Ilven; Ekinci, Sinasi; Oktay, Enver

    2014-06-01

    This study presents nondestructive characterization of microstructure and mechanical properties of heat treated Ti, Ti-Cu, and Ti-6Al-4V titanium-based alloys and 17-4 PH stainless steel alloy for biomedical implant applications. Ti, Ti-Cu, and 17-4 PH stainless steel based implants were produced by powder metallurgy. Ti-6Al-4V alloy was investigated as bulk wrought specimens. Effects of sintering temperature, aging, and grain size on mechanical properties were investigated by nondestructive and destructive tests comparatively. Ultrasonic velocity in specimens was measured by using pulse-echo and transmission methods. Electrical conductivity of specimens was determined by eddy current tests. Determination of Young's modulus and strength is important in biomedical implants. Young's modulus of specimens was calculated by using ultrasonic velocities. Calculated Young's modulus values were compared and correlated with experimental values.

  3. A comparison of traditional and emerging ultrasonic methods for the nondestructive evaluation of polymer matrix composites subjected to impact damage

    NASA Astrophysics Data System (ADS)

    Martin, Richard E.; Roth, Donald J.; Pergantis, Charles G.; Sandhu, Jaswinder S.

    2004-07-01

    This paper presents the results of a comparison study of three ultrasonic nondestructive evaluation (NDE) methods applied to polymer matrix composite (PMC) specimens subjected to impact damage. Samples mainly consisted of various thicknesses of graphite/epoxy coupon panels impacted with various energy levels. Traditional pulse-echo and through transmission ultrasonic c-scan techniques were applied to impacted samples and served as the basis for comparison. Specimens were then inspected using acoustography, a large field ultrasonic inspection technique that is analogous to real-time X-ray imaging. Acoustography utilizes a unique, wide area two-dimensional (2-D) detector, called an acousto-optic (AO) sensor, to directly convert ultrasound into visual images; much like an image intensifier in real-time radiography. Finally, a newly developed guided wave scanning system was utilized to inspect the same set of samples. This system uses two transducers in a pitch catch configuration to examine the total (multi-mode) ultrasonic response in its inspection analysis. Several time- and frequency-domain parameters are calculated from the ultrasonic guided wave signal at each scan location to form images. Results are presented for all of the methods demonstrating each technique's detection capabilities and highlighting their advantages and disadvantages.

  4. Nanophononic thin-film filters and mirrors studied by picosecond ultrasonics

    NASA Astrophysics Data System (ADS)

    Lanzillotti-Kimura, N. D.; Perrin, B.; Fainstein, A.; Jusserand, B.; Lemaître, A.

    2010-02-01

    Optimized acoustic phonon thin-film filters are studied by picosecond ultrasonics. A broadband mirror and a color filter based on aperiodic multilayers were optimized to work in the subterahertz range, and grown by molecular beam epitaxy. Time resolved differential optical reflectivity experiments were performed with pump and probe pulses incident on opposite sides of the substrate. We provide broadband transmission curves for the phonon devices. The results are in good agreement with standard transfer matrix method simulations. In addition, we analyze the effects of the free surface and the influence of an Al capping layer on the response of the aperiodic devices.

  5. [RovoIving ultrasonic probe for medical endoscope imaging system based on USB2.0].

    PubMed

    Chen, Xiaodong; Wen, Shijie; Yu, Daoyin

    2008-10-01

    This paper mainly introduces the design and implementation of rotary scanning imaging for Endoscopic Ultrasonography System based on USB2.0. The ultrasonic pulse-echo imaging technique has been used. In the paper, we simply introduce the emission circuit, receiving circuit and isolation circuit. According to the character of rotary scanning, we design the synchronous control circuit based on FPGA and data transmission circuit based on USB2.0. Finally the original polar coordinate image is transformed to rectangular coordinate grey image through coordinate transformation. The system performances have been validated by the experimental result gotten by scanning a specific object with continuous rotary motor. PMID:19024444

  6. Photonic ultra-wideband pulse generation, hybrid modulation and dispersion-compensation-free transmission in multi-access communication systems.

    PubMed

    Tan, Kang; Shao, Jing; Sun, Junqiang; Wang, Jian

    2012-01-16

    We propose and demonstrate a scheme for optical ultrawideband (UWB) pulse generation by exploiting a half-carrier-suppressed Mach-Zehnder modulator (MZM) and a delay-interferometer- and wavelength-division-multiplexer-based, reconfigurable and multi-channel differentiator (DWRMD). Multi-wavelength, polarity- and shape-switchable UWB pulses of monocycle, doublet, triplet, and quadruplet are experimentally generated simply by tuning two bias voltages to modify the carrier-suppression ratio of MZM and the differential order of DWRMD respectively. The pulse position modulation, pulse shape modulation, pulse amplitude modulation and binary phase-shift keying modulation of UWB pulses can also be conveniently realized with the same scheme structure, which indicates that the hybrid modulation of those four formats can be achieved. Consequently, the proposed approach has potential applications in multi-shape, multi-modulation and multi-access UWB-over-fiber communication systems. PMID:22274463

  7. Ultrasonic generator and detector using an optical mask having a grating for launching a plurality of spatially distributed, time varying strain pulses in a sample

    DOEpatents

    Maris, Humphrey J. (Barrington, RI)

    2002-01-01

    A method and a system are disclosed for determining at least one characteristic of a sample that contains a substrate and at least one film disposed on or over a surface of the substrate. The method includes a first step of placing a mask over a free surface of the at least one film, where the mask has a top surface and a bottom surface that is placed adjacent to the free surface of the film. The bottom surface of the mask has formed therein or thereon a plurality of features for forming at least one grating. A next step directs optical pump pulses through the mask to the free surface of the film, where individual ones of the pump pulses are followed by at least one optical probe pulse. The pump pulses are spatially distributed by the grating for launching a plurality of spatially distributed, time varying strain pulses within the film, which cause a detectable change in optical constants of the film. A next step detects a reflected or a transmitted portion of the probe pulses, which are also spatially distributed by the grating. A next step measures a change in at least one characteristic of at least one of reflected or transmitted probe pulses due to the change in optical constants, and a further step determines the at least one characteristic of the sample from the measured change in the at least one characteristic of the probe pulses. An optical mask is also disclosed herein, and forms a part of these teachings.

  8. Ultrasonic generator and detector using an optical mask having a grating for launching a plurality of spatially distributed, time varying strain pulses in a sample

    DOEpatents

    Maris, Humphrey J. (Barrington, RI)

    2003-01-01

    A method and a system are disclosed for determining at least one characteristic of a sample that contains a substrate and at least one film disposed on or over a surface of the substrate. The method includes a first step of placing a mask over a free surface of the at least one film, where the mask has a top surface and a bottom surface that is placed adjacent to the free surface of the film. The bottom surface of the mask has formed therein or thereon a plurality of features for forming at least one grating. A next step directs optical pump pulses through the mask to the free surface of the film, where individual ones of the pump pulses are followed by at least one optical probe pulse. The pump pulses are spatially distributed by the grating for launching a plurality of spatially distributed, time varying strain pulses within the film, which cause a detectable change in optical constants of the film. A next step detects a reflected or a transmitted portion of the probe pulses, which are also spatially distributed by the grating. A next step measures a change in at least one characteristic of at least one of reflected or transmitted probe pulses due to the change in optical constants, and a further step determines the at least one characteristic of the sample from the measured change in the at least one characteristic of the probe pulses. An optical mask is also disclosed herein, and forms a part of these teachings.

  9. Asymmetric Ultrasonic Pulse Radiation Using Electromagnetic-Induction Transducer and PZT(Pb(Zr-Ti)O3) Transducer with Wave Synthesis Method

    NASA Astrophysics Data System (ADS)

    Endoh, Nobuyuki; Yamamoto, Koji

    1993-05-01

    In medical applications, especially in urology, we use a fragmentation calculus technique with shock waves. This technique is very profitable because of no abdominal surgery for a human being. Large negative sound amplitude pulses, however, can cause problems such as internal hemorrhage or pain in the human body. The final goal of this study is to develop a means to project an intense positive unipolar pulse without negative sound pressure. We improved a composite transducer consisting of an electromagnetic-induction-type (EMI) transducer and PZT (Pb(Zr-Ti)O3) transducers. An EMI transducer consisting of a metal coil and vibration membrane can project intense sound pulses into water. In order to suppress its negative sound pressure, we project a compensation pulse with PZT transducers using an inverse filtering method. An asymmetric pulse whose P+ to P- amplitude ratio was very high was projected in water.

  10. Laser ultrasonic diagnostics of residual stress.

    PubMed

    Karabutov, Alexander; Devichensky, Anton; Ivochkin, Alexander; Lyamshev, Michael; Pelivanov, Ivan; Rohadgi, Upendra; Solomatin, Vladimir; Subudhi, Manomohan

    2008-11-01

    Ultrasonic NDE is one of the most promising methods for non-destructive diagnostics of residual stresses. However the relative change of sound velocity, which is directly proportional to applied stress, is extremely small. An initial stress of 100 MPa produces the result of deltaV/V approximately 10(-4). Therefore measurements must be performed with high precision. The required accuracy can be achieved with laser-exited ultrasonic transients. Radiation from a Nd-YAG laser (pulse duration 7 ns, pulse energy 100 microJ) was absorbed by the surface of the sample. The exited ultrasonic transients resembled the form of laser pulses. A specially designed optoacoustic transducer was used both for the excitation and detecting of the ultrasonic pulses. The wide frequency band of the piezodetector made it possible to achieve the time-of-flight measurements with an accuracy of about 0.5 ns. This technique was used for measuring of plane residual stress in welds and for in-depth testing of subsurface residual stresses in metals. Plane stress distribution for welded metallic plates of different thicknesses (2-8 mm) and the subsurface stress distribution for titanium and nickel alloys were obtained. The results of conventional testing are in good agreement with the laser ultrasonic method. PMID:18762308

  11. In situ monitoring of damage in SiC\\/SiC composites using acousto-ultrasonics

    Microsoft Academic Search

    Andrew L. Gyekenyesi; Gregory N. Morscher; Laura M. Cosgriff

    2006-01-01

    Acousto-ultrasonics (AU) is a nondestructive evaluation (NDE) technique that utilizes two ultrasonic transducers to interrogate the condition of a test specimen. The sending transducer introduces an ultrasonic pulse at a point on the surface of the specimen while a receiving transducer detects the signal after it has passed through the material. The aim of the method is to correlate certain

  12. Modeling Angle Beam Ultrasonic Testing Using Multi-Gaussian Beams

    Microsoft Academic Search

    Hak-Joon Kim; Joon-Soo Park; Sung-Jin Song

    2004-01-01

    This paper proposes a new approach to modeling angle beam ultrasonic testing that can predict pulse-echo signals, in an absolute and computationally efficient manner, from various reflectors in steel welded joints. This approach relies on a model of the entire ultrasonic measurement process, a model which requires one to solve three subsidiary problems; 1) determination of a system efficiency factor,

  13. Ultrasonic method for inspection of the propellant grain in the space shuttle solid rocket booster

    NASA Astrophysics Data System (ADS)

    Doyle, T. E.; Degtyar, A. D.; Sorensen, K. P.; Kelso, M. J.; Berger, T. A.

    2000-05-01

    Defects in solid rocket propellant may affect the safe operation of a space launch vehicle. The Space Shuttle reusable solid rocket motor (RSRM) is therefore routinely inspected with radiography for voids, cracks, and inclusions. Ultrasonic methods can be used to supplement radiography when an indication is difficult to interpret due to the projection geometry or low contrast. Such a method was developed to inspect a local region of propellant in an RSRM forward segment for a suspect inclusion. The method used a through-transmission approach, with a stationary transmitter on the propellant grain inside the segment and a receiving transducer scanned over the case surface. Low frequency (?250 kHz) pulses were propagated through 10-12 inches of propellant, 0.5 inches of NBR insulation, and 0.5 inches of steel case. Through-transmission images were constructed using time-of-flight analysis of the waveforms. The ultrasonic inspections supported results from extended radiographic studies, showing that the indication was not an inclusion but an artifact resulting from liner thickness variations and a low X-ray projection angle in the segment's dome region. This work demonstrated the feasibility of using ultrasonics for inspection of propellant grain in steel-cased rocket motors.

  14. Ultrasonic imaging front-end design for CMUT: A 3-level 30Vpp pulse-shaping pulser with improved efficiency and a noise-optimized receiver

    E-print Network

    Chen, Kailiang

    A four-channel analog front-end (AFE) transceiver chip for medical ultrasound imaging is demonstrated. The high voltage transmitter uses a 3-level pulse-shaping technique to deliver over 50% more acoustic power for the ...

  15. On Variant Strategies To Solve The Magnitude Least Squares Optimization Problem In Parallel Transmission Pulse Design And Under Strict SAR And Power Constraints

    E-print Network

    Hoyos-Iruarrizaga, Andres; Massire, Aurélien; Amadon, Alexis; Boulant, Nicolas

    2013-01-01

    Parallel transmission has been a very promising candidate technology to mitigate the inevitable radio-frequency field inhomogeneity in magnetic resonance imaging (MRI) at ultra-high field (UHF). For the first few years, pulse design utilizing this technique was expressed as a least squares problem with crude power regularizations aimed at controlling the specific absorption rate (SAR), hence the patient safety. This approach being suboptimal for many applications sensitive mostly to the magnitude of the spin excitation, and not its phase, the magnitude least squares (MLS) problem then was first formulated in 2007. Despite its importance and the availability of other powerful numerical optimization methods, this problem yet has been faced exclusively by the pulse designer with the so-called variable exchange method. In this paper, we investigate other strategies and incorporate directly the strict SAR and hardware constraints. Different schemes such as sequential quadratic programming (SQP), interior point (I-...

  16. Ultrasonic attenuation - Q measurements on 70215,29. [lunar rock

    NASA Technical Reports Server (NTRS)

    Warren, N.; Trice, R.; Stephens, J.

    1974-01-01

    Ultrasonic attenuation measurements have been made on an aluminum alloy, obsidian, and rock samples including lunar sample 70215,29. The measurement technique is based on a combination of the pulse transmission method and the forced resonance method. The technique is designed to explore the problem of defining experimentally, the Q of a medium or sample in which mode conversion may occur. If modes are coupled, the measured attenuation is strongly dependent on individual modes of vibration, and a range of Q-factors may be measured over various resonances or from various portions of a transient signal. On 70215,29, measurements were made over a period of a month while the sample outgassed in hard varuum. During this period, the highest measured Q of this sample increased from a few hundred into the range of 1000-1300.

  17. Calcaneal ultrasonic measurements discriminate hip fracture independently of bone mass

    Microsoft Academic Search

    C. H. Turner; M. Peacock; L. Timmerman; J. M. Neal; C. C. Johnston

    1995-01-01

    We studied 336 elderly white women, of whom 22 had previously suffered a hip fracture and 22 had previously suffered a vertebral fracture. All subjects were 60 years old or older with a mean age of 73.7 years. Measurements of ultrasonic transmission velocity (UTV), broad-band ultrasonic attenuation (BUA) and stiffness (STF) were made at the os calcis using a Lunar

  18. Ultrasonic-Assisted Convective Drying of Apple Slices

    Microsoft Academic Search

    H. T. Sabarez; J. A. Gallego-Juarez; E. Riera

    2012-01-01

    A promising approach for the application of ultrasound to assist in convective food drying was developed and tested in this study. The application of ultrasound is based on the transmission of ultrasonic energy as a combination of airborne contacts and through a series of solid contacts between the ultrasound element and the product tray as the ultrasonic vibration transmitting surface.

  19. Simplified flexible-PON upstream transmission using pulse position modulation at ONU and DSP-enabled soft-combining at OLT for adaptive link budgets.

    PubMed

    Liu, Xiang; Effenberger, Frank; Chand, Naresh

    2015-03-01

    We demonstrate a flexible modulation and detection scheme for upstream transmission in passive optical networks using pulse position modulation at optical network unit, facilitating burst-mode detection with automatic decision threshold tracking, and DSP-enabled soft-combining at optical line terminal. Adaptive receiver sensitivities of -33.1 dBm, -36.6 dBm and -38.3 dBm at a bit error ratio of 10-4 are respectively achieved for 2.5 Gb/s, 1.25 Gb/s and 625 Mb/s after transmission over a 20-km standard single-mode fiber without any optical amplification. PMID:25836897

  20. Ultrasonic Interferometers Revisited

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2007-01-01

    I have been tinkering with ultrasonic transducers once more. In earlier notes I reported on optics-like experiments performed with ultrasonics, described a number of ultrasonic interferometers, and showed how ultrasonic transducers can be used for Fourier analysis. This time I became interested in trying the technique of using two detectors in…

  1. Ultrasonic colour Doppler imaging

    PubMed Central

    Evans, David H.; Jensen, Jørgen Arendt; Nielsen, Michael Bachmann

    2011-01-01

    Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue anatomy. The most common use of the technique is to image the movement of blood through the heart, arteries and veins, but it may also be used to image the motion of solid tissues such as the heart walls. Colour Doppler imaging is now provided on almost all commercial ultrasound machines, and has been found to be of great value in assessing blood flow in many clinical conditions. Although the method for obtaining the velocity information is in many ways similar to the method for obtaining the anatomical information, it is technically more demanding for a number of reasons. It also has a number of weaknesses, perhaps the greatest being that in conventional systems, the velocities measured and thus displayed are the components of the flow velocity directly towards or away from the transducer, while ideally the method would give information about the magnitude and direction of the three-dimensional flow vectors. This review briefly introduces the principles behind colour Doppler imaging and describes some clinical applications. It then describes the basic components of conventional colour Doppler systems and the methods used to derive velocity information from the ultrasound signal. Next, a number of new techniques that seek to overcome the vector problem mentioned above are described. Finally, some examples of vector velocity images are presented. PMID:22866227

  2. Transmission of endemic ST22-MRSA-IV on four acute hospital wards investigated using a combination of spa, dru and pulsed-field gel electrophoresis typing.

    PubMed

    Creamer, E; Shore, A C; Rossney, A S; Dolan, A; Sherlock, O; Fitzgerald-Hughes, D; Sullivan, D J; Kinnevey, P M; O'Lorcain, P; Cunney, R; Coleman, D C; Humphreys, H

    2012-11-01

    The transmission of meticillin-resistant Staphylococcus aureus (MRSA) between individual patients is difficult to track in institutions where MRSA is endemic. We investigated the transmission of MRSA where ST22-MRSA-IV is endemic on four wards using demographic data, patient and environmental screening, and molecular typing of isolates. A total of 939 patients were screened, 636 within 72 h of admission (on admission) and 303 >72 h after admission, and 1,252 environmental samples were obtained. Isolates were typed by spa, dru and pulsed-field gel electrophoresis (PFGE) typing. A composite dendrogram generated from the three sets of typing data was used to divide isolates into 'dendrogram groups' (DGs). Ten percent of patients (92/939) were MRSA-positive; 7 % (44/636) on admission and 16 % (48/303) >72 h after admission (p?=?0.0007). MRSA was recovered from 5 % of environmental specimens (65/1,252). Most isolates from patients (97 %, 85/88) and the environment (97 %, 63/65) exhibited the ST22-MRSA-IV genotype. Four DGs (DG1, DG4, DG16 and DG17) accounted for 58 % of ST22-MRSA-IV isolates from patients. Epidemiological evidence suggested cross-transmission among 44/92 patients (48 %) but molecular typing confirmed probable cross-transmission in only 11 instances (13 %, 11/88), with the majority of cross-transmission (64 %; 7/11) occurring on one ward. In the setting of highly clonal endemic MRSA, the combination of local epidemiology, PFGE, spa and dru typing provided valuable insights into MRSA transmission. PMID:22814876

  3. Digital ultrasonic signal processing: Primary ultrasonics task and transducer characterization use and detailed description

    NASA Technical Reports Server (NTRS)

    Hammond, P. L.

    1979-01-01

    This manual describes the use of the primary ultrasonics task (PUT) and the transducer characterization system (XC) for the collection, processing, and recording of data received from a pulse-echo ultrasonic system. Both PUT and XC include five primary functions common to many real-time data acquisition systems. Some of these functions are implemented using the same code in both systems. The solicitation and acceptance of operator control input is emphasized. Those operations not under user control are explained.

  4. Ultrasonic transducer

    DOEpatents

    Taylor, Steven C.; Kraft, Nancy C.

    2007-03-13

    An ultrasonic transducer having an effective center frequency of about 42 MHz; a bandwidth of greater than 85% at 6 dB; a spherical focus of at least 0.5 inches in water; an F4 lens; a resolution sufficient to be able to detect and separate a 0.005 inch flat-bottomed hole at 0.005 inches below surface; and a beam size of approximately 0.006–0.008 inches measured off a 11/2 mm ball in water at the transducer's focal point.

  5. Coherent Brillouin spectroscopy in a strongly scattering liquid by picosecond ultrasonics

    E-print Network

    Maznev, Alexei

    In a modification of a picosecond ultrasonic technique, a short acoustic pulse is launched into a liquid sample by a laser pulse absorbed in a semitransparent transducer film and is detected via coherent Brillouin scattering ...

  6. Assessment and Calibration of a Crimp Tool Equipped with Ultrasonic Analysis Features

    NASA Technical Reports Server (NTRS)

    Yost, William T. (Inventor); Perey, Daniel F. (Inventor); Cramer, K. Elliott (Inventor)

    2013-01-01

    A method is provided for calibrating ultrasonic signals passed through a crimp formed with respect to a deformable body via an ultrasonically-equipped crimp tool (UECT). The UECT verifies a crimp quality using the ultrasonic signals. The method includes forming the crimp, transmitting a first signal, e.g., a pulse, to a first transducer of the UECT, and converting the first signal, using the first transducer, into a second signal which defines an ultrasonic pulse. This pulse is transmitted through the UECT into the crimp. A second transducer converts the second signal into a third signal, which may be further conditioned, and the ultrasonic signals are calibrated using the third signal or its conditioned variant. An apparatus for calibrating the ultrasonic signals includes a pulse module (PM) electrically connected to the first and second transducers, and an oscilloscope or display electrically connected to the PM for analyzing an electrical output signal therefrom.

  7. Femtosecond measurements of near-infrared pulse induced mid-infrared transmission modulation of quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Cai, Hong; Liu, Sheng; Lalanne, Elaine; Guo, Dingkai; Chen, Xing; Wang, Xiaojun; Choa, Fow-Sen; Johnson, Anthony M.

    2014-05-01

    We temporally resolved the ultrafast mid-infrared transmission modulation of quantum cascade lasers (QCLs) using a near-infrared pump/mid-infrared probe technique at room temperature. Two different femtosecond wavelength pumps were used with photon energy above and below the quantum well (QW) bandgap. The shorter wavelength pump modulates the mid-infrared probe transmission through interband transition assisted mechanisms, resulting in a high transmission modulation depth and several nanoseconds recovery lifetime. In contrast, pumping with a photon energy below the QW bandgap induces a smaller transmission modulation depth but much faster (several picoseconds) recovery lifetime, attributed to intersubband transition assisted mechanisms. The latter ultrafast modulation (>60 GHz) could provide a potential way to realize fast QCL based free space optical communication.

  8. Ultrasonic hydrometer

    SciTech Connect

    Swoboda, C.A.

    1984-04-17

    The disclosed ultrasonic hydrometer determines the specific gravity (density) of the electrolyte of a wet battery, such as a lead-acid battery. The hydrometer utilizes a transducer that when excited emits an ultrasonic impulse that traverses through the electrolyte back and forth between spaced sonic surfaces. The transducer detects the returning impulse, and means measures the time ''t'' between the initial and returning impulses. Considering the distance ''d'' between the spaced sonic surfaces and the measured time ''t'', the sonic velocity ''V'' is calculated with the equation ''V=2d/t''. The hydrometer also utilizes a thermocouple to measure the electrolyte temperature. A hydrometer database correlates three variable parameters including sonic velocity in and temperature and specific gravity of the electrolyte, for temperature values between 0/sup 0/ and 40/sup 0/ C. and for specific gravity values between 1.05 and 1.30. Upon knowing two parameters (the calculated sonic velocity and the measured temperature), the third parameter (specific gravity) can be uniquely found in the database. The hydrometer utilizes a microprocessor for data storage and manipulation. The disclosed modified battery has a hollow spacer nub on the battery side wall, the sonic surfaces being on the inside of the nub and the electrolyte filling between the surfaces to the exclusion of intervening structure. An accessible pad exposed on the nub wall opposite one sonic surface allows the reliable placement thereagainst of the transducer.

  9. Wire Crimp Termination Verification Using Ultrasonic Inspection

    NASA Technical Reports Server (NTRS)

    Perey, Daniel F.; Cramer, K. Elliott; Yost, William T.

    2007-01-01

    The development of a new ultrasonic measurement technique to quantitatively assess wire crimp terminations is discussed. The amplitude change of a compressional ultrasonic wave propagating through the junction of a crimp termination and wire is shown to correlate with the results of a destructive pull test, which is a standard for assessing crimp wire junction quality. Various crimp junction pathologies such as undercrimping, missing wire strands, incomplete wire insertion, partial insulation removal, and incorrect wire gauge are ultrasonically tested, and their results are correlated with pull tests. Results show that the nondestructive ultrasonic measurement technique consistently (as evidenced with destructive testing) predicts good crimps when ultrasonic transmission is above a certain threshold amplitude level. A physics-based model, solved by finite element analysis, describes the compressional ultrasonic wave propagation through the junction during the crimping process. This model is in agreement within 6% of the ultrasonic measurements. A prototype instrument for applying this technique while wire crimps are installed is also presented. The instrument is based on a two-jaw type crimp tool suitable for butt-splice type connections. Finally, an approach for application to multipin indenter type crimps will be discussed.

  10. Fiberized laser ultrasonic source for process monitoring and biomedical applications

    NASA Astrophysics Data System (ADS)

    Fomitchov, Pavel A.; Kromine, Alexei K.; Krishnaswamy, Sridhar; Achenbach, Jan D.

    2000-08-01

    A new design for a fiberized laser ultrasonic source for process monitoring and bio-medical applications is proposed. The laser ultrasonic source consists of a pulsed laser, a fiber-optic cable, and a generation head. The generation head is a miniature hermetically sealed chamber, which can be embedded into solid structures or immersed in liquid media. The face of the chamber acts as a target for the laser irradiation. Bulk ultrasonic waves generated inside of the target are transmitted into the surrounding liquid media or solid structure. It is shown that ultrasonic pulses of 1 microsecond(s) to 30 ns duration can be generated. Sources with different radiation patterns with respect to the optical axis of the fiber, such as normal, angular, and focused, have been devised. An example use of these sources combined with a fiber optic ultrasonic sensor for inspection of small tubes is presented.

  11. Three-dimensional imaging of biological cells with picosecond ultrasonics

    NASA Astrophysics Data System (ADS)

    Danworaphong, Sorasak; Tomoda, Motonobu; Matsumoto, Yuki; Matsuda, Osamu; Ohashi, Toshiro; Watanabe, Hiromu; Nagayama, Masafumi; Gohara, Kazutoshi; Otsuka, Paul H.; Wright, Oliver B.

    2015-04-01

    We use picosecond ultrasonics to image animal cells in vitro—a bovine aortic endothelial cell and a mouse adipose cell—fixed to Ti-coated sapphire. Tightly focused ultrashort laser pulses generate and detect GHz acoustic pulses, allowing three-dimensional imaging (x, y, and t) of the ultrasonic propagation in the cells with ˜1 ?m lateral and ˜150 nm depth resolutions. Time-frequency representations of the continuous-wavelet-transform amplitude of the optical reflectivity variations inside and outside the cells show GHz Brillouin oscillations, allowing the average sound velocities of the cells and their ultrasonic attenuation to be obtained as well as the average bulk moduli.

  12. Interactive signal analysis and ultrasonic data collection system user's manual

    NASA Technical Reports Server (NTRS)

    Smith, G. R.

    1978-01-01

    The interactive signal analysis and ultrasonic data collection system (ECHO1) is a real time data acquisition and display system. ECHO1 executed on a PDP-11/45 computer under the RT11 real time operating system. Extensive operator interaction provided the requisite parameters to the data collection, calculation, and data modules. Data were acquired in real time from a pulse echo ultrasonic system using a Biomation Model 8100 transient recorder. The data consisted of 2084 intensity values representing the amplitude of pulses transmitted and received by the ultrasonic unit.

  13. An ultrasonic plethysmograph for space flight applications

    NASA Technical Reports Server (NTRS)

    Bhagat, P. K.; Lafferty, J. F.; Bowman, D.; Kadaba, M. P.

    1980-01-01

    The development of an ultrasonic plethysmograph based on the transit time measurement principle is reported, which meets the space-imposed requirements for evaluating cardiovascular deconditioning. It consists of a pulse generator, pulse receiver amplifier, voltage comparator, synchronous pulse generator, elapsed time counter, and transmit and receive piezoelectric crystals resonant at 2 MHz and of 3 mm diameter. The transit time for an ultrasonic pulse to propagate across a limb cross section is computed in a digital fashion using a 32 MHz clock, and resolution is 0.049 mm with the range being approximately 200 mm. Experimental results regarding dynamic system response were found comparable in both accuracy and sensitivity to those of a Whitney strain gage using a 50 torr venous occlusion.

  14. Surfaces and thin films studied by picosecond ultrasonics. Progress report, December 1, 1989--November 30, 1992

    SciTech Connect

    Maris, J.H.; Tauc, J.

    1992-05-01

    This research is the study of thin films and interfaces via the use of the picosecond ultrasonic technique. In these experiments ultrasonic waves are excited in a structure by means of a picosecond light pulse (``pump pulse``). The propagation of these waves is detected through the use of a probe light pulse that is time-delayed relative to the pump. This probe pulse measures the change {Delta}R(t) in the optical reflectivity of the structure that occurs because the ultrasonic wave changes the optical properties of the structure. This technique make possible the study of the attenuation and velocity of ultrasonic waves up to much higher frequencies than was previously possible (up to least 500 GHz). In addition, the excellent time-resolution of the method makes it possible to study nanostructures of linear dimensions down to 100 {Angstrom} or less by ultrasonic pulse-echo techniques. 25 refs.

  15. Effective ultrasonication process for better colloidal dispersion of nanofluid.

    PubMed

    Mahbubul, I M; Saidur, R; Amalina, M A; Elcioglu, E B; Okutucu-Ozyurt, T

    2015-09-01

    Improving dispersion stability of nanofluids through ultrasonication has been shown to be effective. Determining specific conditions of ultrasonication for a certain nanofluid is necessary. For this purpose, nanofluids of varying nanoparticle concentrations were prepared and studied to find out a suitable and rather mono-dispersed concentration (i.e., 0.5vol.%, determined through transmission electron microscopy (TEM) analyses). This study aims to report applicable ultrasonication conditions for the dispersion of Al2O3 nanoparticles within H2O through the two-step production method. The prepared samples were ultrasonicated via an ultrasonic horn for 1-5h at two different amplitudes (25% and 50%). The microstructure, particle size distribution (PSD), and zeta potentials were analyzed to investigate the dispersion characteristics. Better particle dispersion, smaller aggregate sizes, and higher zeta potentials were observed at 3 and 5h of ultrasonication duration for the 50% and 25% of sonicator power amplitudes, respectively. PMID:25616639

  16. Production of aqueous spherical gold nanoparticles using conventional ultrasonic bath

    PubMed Central

    2012-01-01

    A conventional ultrasonic bath was used to examine the feasibility of forming aqueous spherical gold nanoparticles (GNPs) under atmospheric conditions. The effects of ultrasonic energy on the size and morphology of GNPs were also investigated. Highly monodispersed spherical GNPs were successfully synthesised by sodium citrate reduction in a conventional ultrasonic bath, without an additional heater or magnetic stirrer, as evidenced by ultraviolet–visible spectra and transmission electron microscopy. Ultrasonic energy was shown to be a key parameter for producing spherical GNPs of tunable sizes (20 to 50?nm). A proposed scheme for understanding the role of ultrasonic energy in the formation and growth of GNPs was discussed. The simple single-step method using just a conventional ultrasonic bath as demonstrated in this study offers new opportunities in the production of aqueous suspensions of monodispersed spherical GNPs. PMID:22839598

  17. Design of polarizers for a mega-watt long-pulse millimeter-wave transmission line on the large helical device

    NASA Astrophysics Data System (ADS)

    Ii, T.; Kubo, S.; Shimozuma, T.; Kobayashi, S.; Okada, K.; Yoshimura, Y.; Igami, H.; Takahashi, H.; Ito, S.; Mizuno, Y.; Okada, K.; Makino, R.; Kobayashi, K.; Goto, Y.; Mutoh, T.

    2015-02-01

    The polarizer is one of the critical components in a high-power millimeter-wave transmission line. It requires full and highly efficient coverage of any polarization states, high-power tolerance, and low-loss feature. Polarizers with rounded shape at the edge of the periodic groove surface are designed and fabricated by the machining process for a mega-watt long-pulse millimeter-wave transmission line of the electron cyclotron resonance heating system in the large helical device. The groove shape of ?/8- and ?/4-type polarizers for an 82.7 GHz transmission line is optimally designed in an integral method developed in the vector theories of diffraction gratings so that the efficiency to realize any polarization state can be maximized. The dependence of the polarization states on the combination of the two polarizer rotation angles (??/8, ??/4) is examined experimentally in a low-power test with the newly developed polarization monitor. The results show that the measured polarization characteristics are in good agreement with the calculated ones.

  18. On the Dissipative Complex Ginzburg-Landau Equation Governing the Propagation of Solitary Pulses in Dissipative Nonlinear Transmission Lines

    Microsoft Academic Search

    E. Kengne; C. Tadmon; R. Vaillancourt

    2009-01-01

    A class of dissipative complex Ginzburg-Landau (DCGL) equations that govern the wave propagation in dissipative nonlinear transmission lines is solved exactly by means of the Hirota bilinear method. Two-soliton solutions of the DCGL equations, from which the one- soliton solutions are deduced, are obtained in analytical form. The modified Hirota method imposes some restrictions on the coefficients of the equations,

  19. Transmission communication

    E-print Network

    Chen, Sheng

    ELEC3028 Digital Transmission -- MODEM S Chen Revision of Lecture 1 . Major blocks of digital communication system . MODEM functions . Channel has finite bandwidth and introduces noise: two main factors recovering of transmitted data symbols MODEM components pulse shaping Tx/Rx filter pair modulator

  20. Bundled hollow optical fibers for transmission of high-peak-power Q-switched Nd:YAG laser pulses

    Microsoft Academic Search

    Ozgur Yilmaz; Mitsunobu Miyagi; Yuji Matsuura

    2006-01-01

    A hollow-fiber bundle was designed and used to deliver high-peak-power pulses from a Q-switched Nd:YAG laser. An 80 cm long bundle with a total diameter of 5.5 mm was composed of 37 glass capillaries with bore diameters of 0.7 mm. Beam-resizing optics with two lenses were used to couple the laser beam into the bundle. The measured coupling loss due

  1. Non-uniform triggering of gg-nMOSt investigated by combined emission microscopy and transmission line pulsing

    Microsoft Academic Search

    Christian Russ; Karlheinz Bock; Mahmoud Rasras; Ingrid De Wolf; Guido Groeseneken; Herman E. Maes

    1998-01-01

    The triggering of grounded gate nMOSFET (gg-nMOS) and field-oxide devices (FOXFETs), essential for optimized ESD protection design, is addressed by TLP-pulsed emission microscopy. Current nonuniformity and instability effects in snapback operation under DC and TLP conditions are demonstrated. The comprehensive correlation of emission and electrical behaviour allows an improved interpretation of device operation. Technological influences on the trigger uniformity are

  2. Ultrasonic imaging techniques for breast cancer detection.

    SciTech Connect

    Goulding, N. R. (Nathan R.); Marquez, J. D. (Joel D.); Prewett, E. M. (Emily M.); Claytor, T. N. (Thomas N.); Nadler, B. R. (Brett Ross); Huang, L. (Lian-Jie)

    2006-01-01

    Improving the resolution and specificity of current ultrasonic imaging technology can enhance its relevance to detection of early-stage breast cancers. Ultrasonic evaluation of breast lesions is desirable because it is quick, inexpensive, and does not expose the patient to potentially harmful ionizing radiation. Improved image quality and resolution enables earlier detection and more accurate diagnoses of tumors, thus reducing the number of biopsies performed, increasing treatment options, and lowering mortality, morbidity, and remission percentages. In this work, a novel ultrasonic imaging reconstruction method that exploits straight-ray migration is described. This technique, commonly used in seismic imaging, accounts for scattering more accurately than standard ultrasonic approaches, thus providing superior image resolution. A breast phantom with various inclusions is imaged using a pulse-echo approach. The data are processed using the ultrasonic migration method and results are compared to standard linear ultrasound and to x-ray computed tomography (CT) scans. For an ultrasonic frequency of 2.25 MHz, imaged inclusions and features of approximately 1mm are resolved, although better resolution is expected with minor modifications. Refinement of this application using other imaging techniques such as time-reversal mirrors (TRM), synthetic aperture focusing technique (SAFT), decomposition of the time reversal operator (DORT), and factorization methods is also briefly discussed.

  3. Analysis of laser generated ultrasonic wave frequency characteristics induced by a partially closed surface-breaking crack.

    PubMed

    Li, Jia; Zhang, Hongchao; Ni, Chenyin; Shen, Zhonghua

    2013-06-20

    This research focuses on analyzing the frequency characteristics of ultrasonic waves induced by a partially closed surface-breaking crack. When acoustic waves interact with the crack, transmission, reflection, and mode conversions occur and the frequency characteristics of signals perform obvious changes. A pulsed laser line source is used to generate ultrasonic waves in the sample with a partially closed surface-breaking crack, and one can see how the frequency characteristics of detected signals change as the pulsed laser beam scans across the sample surface. The optical deflection beam method is developed to detect the ultrasonic signals experimentally. The fast Fourier transform (FFT) is used to analyze the time-domain data, and the FFT data are visualized by a B-scan plot. A clear disruption in the B-scan can be observed when the laser beam illuminates directly onto the crack, which is due to the changes of frequency characteristics induced by the partially closed crack. A frequency-domain B-scan of numerical simulation results is presented, and the clear disruption can also be observed clearly. PMID:23842158

  4. Ultrasonic position and velocity measurement for a moving object by M-sequence pulse compression using Doppler velocity estimation by spectrum-pattern analysis

    NASA Astrophysics Data System (ADS)

    Ikari, Yohei; Hirata, Shinnosuke; Hachiya, Hiroyuki

    2015-07-01

    Pulse compression using a maximum-length sequence (M-sequence) can improve the signal-to-noise ratio (SNR) of the reflected echo in the pulse–echo method. In the case of a moving object, however, the echo is modulated owing to the Doppler effect. The Doppler-shifted M-sequence-modulated signal cannot be correlated with the reference signal that corresponds to the transmitted M-sequence-modulated signal. Therefore, Doppler velocity estimation by spectrum-pattern analysis of a cyclic M-sequence-modulated signal and cross correlations with Doppler-shifted reference signals that correspond to the estimated Doppler velocities has been proposed. In this paper, measurements of the position and velocity of a moving object by the proposed method are described. First, Doppler velocities of the object are estimated using a microphone array. Secondly, the received signal from each microphone is correlated with each Doppler-shifted reference signal. Then, the position of the object is determined from the B-mode image formed from all cross-correlation functions. After that, the velocity of the object is calculated from velocity components estimated from the Doppler velocities and the position. Finally, the estimated Doppler velocities, determined positions, and calculated velocities are evaluated.

  5. Ultrasonic characterization of laser ablation

    NASA Astrophysics Data System (ADS)

    Smith, J. A.; Telschow, K. L.

    When a pulsed laser beam strikes the surface of an absorbing material, ultrasonic waves are generated due to thermoelectric expansion and, at higher laser power densities, ablation of the material. These sound generation mechanisms have been the subject of numerous theoretical and experimental studies and are now fairly well understood. In particular, it has been established that at low power densities the thermoelastic mechanism is well described by a surface center of expansion. This mechanism produces a characteristic waveform whose amplitude is proportional to the energy absorbed from the laser pulse and also dependent on the thermal and elastic properties of the material. The ablation ultrasonic source can be described by a point normal force acting on the material surface. For laser power densities near the ablation onset, the time dependence of the source is that of the laser pulse. The resultant waveform recorded on epicenter (source and detector collinear) has a sharp peak determined by the momentum impulse delivered to the material by the ablation process. Particularly in the near ablation onset region, this ultrasonic displacement peak can be used to characterize the ablation process occurring at the material surface. The onset power density for ablation and subsequent ablation dependence on power density are material dependent and thought to be a function of the heat capacity and thermal conductivity of the material. With this in mind, it is possible that these ablation signals could be used to characterize material microstructures, and perhaps material mechanical properties such as hardness, through microstructural changes of the material thermal parameters. This paper explores this question for samples of Type 304 stainless steel with microstructures controlled through work hardening and annealing.

  6. Characterization of nonlinear absorption of InN epitaxial films with femtosecond pulsed transmission Z-scan measurements

    NASA Astrophysics Data System (ADS)

    Tsai, Tsong-Ru; Wu, Tsung-Han; Liao, Jung-Cheng; Wei, Tai-Huei; Chiang, Hai-Pang; Hwang, Jih-Shang; Tsai, Din-Ping; Chen, Yang-Fang

    2009-03-01

    The femtosecond pulsed Z-scan measurements of the resonant nonlinear optical absorption of the InN epitaxial films in the range of 720-790nm were reported. The absorption saturation behavior was found to gradually decrease with increasing photon energy. The nonlinear optical absorption cross sections of the InN films were estimated and the values are found to be in good agreement with the calculations based on the band-filling model. These results are relevant for the future development of nonlinear optical devices based on InN.

  7. Autonomous data transmission apparatus

    DOEpatents

    Kotlyar, O.M.

    1997-03-25

    A autonomous borehole data transmission apparatus is described for transmitting measurement data from measuring instruments at the downhole end of a drill string by generating pressure pulses utilizing a transducer longitudinally responsive to magnetic field pulses caused by electrical pulses corresponding to the measured downhole parameters. 4 figs.

  8. Autonomous data transmission apparatus

    DOEpatents

    Kotlyar, Oleg M. (4675 W. 3825 S, Salt Lake City, UT 84120)

    1997-01-01

    A autonomous borehole data transmission apparatus for transmitting measurement data from measuring instruments at the downhole end of a drill string by generating pressure pulses utilizing a transducer longitudinally responsive to magnetic field pulses caused by electrical pulses corresponding to the measured downhole parameters.

  9. Optically excited nanoscale ultrasonic transducers.

    PubMed

    Smith, Richard J; Cota, Fernando Perez; Marques, Leonel; Chen, Xuesheng; Arca, Ahmet; Webb, Kevin; Aylott, Jonathon; Somekh, Micheal G; Clark, Matt

    2015-01-01

    In order to work at higher ultrasonic frequencies, for instance, to increase the resolution, it is necessary to fabricate smaller and higher frequency transducers. This paper presents an ultrasonic transducer capable of being made at a very small size and operated at GHz frequencies. The transducers are activated and read optically using pulsed lasers and without physical contact between the instrumentation and the transducer. This removes some of the practical impediments of traditional piezoelectric architectures (such as wiring) and allows the devices to be placed immediately on or within samples, reducing the significant effect of attenuation which is very strong at frequencies above 1?GHz. The transducers presented in this paper exploit simultaneous optical and mechanical resonances to couple the optical input into ultrasonic waves and vice versa. This paper discusses the mechanical and optical design of the devices at a modest scale (a few ?m) and explores the scaling of the transducers toward the sub-micron scale. Results are presented that show how the transducers response changes depending on its local environment and how the resonant frequency shifts when the transducer is loaded by a printed protein sample. PMID:25618053

  10. Passive wireless ultrasonic transducer systems

    NASA Astrophysics Data System (ADS)

    Zhong, C. H.; Croxford, A. J.; Wilcox, P. D.

    2014-02-01

    Inductive coupling and capacitive coupling both offer simple solutions to wirelessly probe ultrasonic transducers. This paper investigates the theory and feasibility of such system in the context of non-destructive evaluation (NDE) applications. Firstly, the physical principles and construction of an inductively coupled transducer system (ICTS) and a capacitively coupled transducer system (CCTS) are introduced. Then the development of a transmission line model with the measured impedance of a bonded piezoelectric ceramic disc representing a sensor attached to an arbitrary solid substrate for both systems is described. The models are validated experimentally. Several applications of CCTS are presented, such CCTS for the underwater and through-composite testing.

  11. Numerical calculations of ultrasonic fields. [STEALTH

    SciTech Connect

    Johnson, J.A.

    1982-02-01

    A code for calculating ultrasonic fields has been developed by revisng the thermal-hydraulics code STEALTH. This code may be used in a wide variety of situations in which a detailed knowledge of a propagating wave field is required. Among the potential used are: interpretation of pulse-echo or pitch-catch ultrasonic signals in complicated geometries; ultrasonic transducer modeling and characterization; optimization and evaluation of transducer design; optimization and reliability of inspection procedures; investigation of the response of different types of reflectors; flaw modeling; and general theoretical acoustics. The code is described, and its limitations and potential are discussed. A discussion of the required input and of the general procedures for running the code is presented. Three sample problems illustrate the input and the use of the code.

  12. Flexible ultrasonic array sensors for health monitoring

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Wu, K.-T.; Song, L.; Liu, Q.; Jen, C.-K.

    2007-04-01

    Flexible ultrasonic array transducers which can be attached to the desired structures or materials for nondestructive testing and structural health monitoring applications at room and elevated temperatures are developed. These flexible ultrasonic transducers (UTs) arrays consist of a thin polyimide membrane with a bottom electrode or stainless steel foil, a piezoelectric lead-zirconate-titanate (PZT) composite film and top electrodes. The flexibility is realized owing to the porosity of piezoelectric film and the thinness of substrate and electrodes. Top and bottom electrode materials are silver paste, silver paint or electroless plated nickel alloys. The UT array is configured by the several top electrodes. The flexible UT has been successfully tested at 150°C and also immersed into water as immersion ultrasonic probe operated in the pulse-echo mode with good signal to noise ratio.

  13. First comparison of electric field induced second harmonic of near-infrared femtosecond laser pulses in reflection and transmission generated from Si/SiO2 interfaces of a silicon membrane

    NASA Astrophysics Data System (ADS)

    Nyamuda, G. P.; Rohwer, E. G.; Steenkamp, C. M.; Stafast, H.

    2011-09-01

    For the first time electric field induced second harmonic (EFISH) generation of femtosecond (fs) laser pulses ( ?=800 nm, ?=75±5 fs, rep. rate=80 MHz, E pulse?10 nJ) is observed in transmission through a thin free-standing silicon (Si) membrane of 10-?m thickness and compared to the well-known EFISH results in reflection by use of the z-scan technique. EFISH in reflection and transmission unequivocally originate from the front and rear Si/SiO2 interfaces, respectively, with SiO2 being the natural oxide on the Si surfaces. Frequency conversion is enhanced by photoinduced electric fields across the Si/SiO2 interfaces caused by charge-carrier injection from Si into the oxide. The z-scan results and time-dependent measurements allow comparison of the EFISH signal amplitudes and time constants detected in transmission and reflection, demonstrating the need for further investigation.

  14. Harmonic generation of an obliquely incident ultrasonic wave in solid-solid contact interfaces.

    PubMed

    Nam, Taehyung; Lee, Taehun; Kim, Chungseok; Jhang, Kyung-Young; Kim, Nohyu

    2012-08-01

    The conventional acoustic nonlinear technique to evaluate the contact acoustic nonlinearity (CAN) at solid-solid contact interfaces (e.g., closed cracks), which uses the through-transmission of normally incident bulk waves, is limited in that access to both the inner and outer surfaces of structures for attaching pulsing and receiving transducers is difficult. The angle beam incidence and reflection technique, where both the pulsing and receiving transducers are located on the same side of the target, may allow the above problem to be overcome. However, in the angle incidence technique, mode-conversion at the contact interfaces as well as the normal and tangential interface stiffness should be taken into account. Based on the linear and nonlinear contact stiffness, we propose a theoretical model for the reflection of an ultrasonic wave angularly incident on contact interfaces. In addition, the magnitude of the CAN-induced second harmonic wave in the reflected ultrasonic wave is predicted. Experimental results obtained for the contact interfaces of A16061-T6 alloy specimens at various loading pressures showed good agreement with theoretical predictions. Such agreement proves the validity of the suggested oblique incidence model. PMID:22410490

  15. Ultrasonic determination of Young's moduli of the coat and core materials of a drug tablet.

    PubMed

    Akseli, Ilgaz; Becker, Douglas C; Cetinkaya, Cetin

    2009-03-31

    Many modern tablet presses have system controls that monitor the force exerted to compress the solid oral dosage forms; however this data provides only limited information about the mechanical state of the tablet due to various process and materials uncertainties. A contact pulse/echo ultrasonic scheme is presented for the determination of the local Young's moduli of the coat and the core materials of enteric-coated and monolayer coated tablets. The Young's modulus of a material compacted into solid dosage can be related to its mechanical hardness and, consequently, its dissolution rate. In the current approach, short ultrasonic pulses are generated by the active element of a delay line transducer and are launched into the tablet. The waveforms reflected from the tablet coat-core interface are captured by the same transducer and are processed for determining the reflection and transmission coefficients of the interface from partially overlapping echoes. The Young's moduli of the coat and the core materials are then extracted from these coefficients. The results are compared to those obtained by an air-coupled acoustic excitation study, and good agreement is found. The described measurement technique provides greater insight into the local physical properties of the solid oral dosage form and, as a result, has the potential to provide better hardness-related performance predictability of compacts. PMID:19059326

  16. Real-time ultrasonic sensing of arc welding processes

    SciTech Connect

    Lott, L.A.; Johnson, J.A.; Smartt, H.B.

    1983-01-01

    NDE techniques are being investigated for fusion zone sensing of arc welding processes for closed-loop process control. An experimental study of pulse-echo ultrasonics for sensing the depth of penetration of molten weld pools in structural metals during welding indicates that real-time ultrasonic sensing is feasible. Results on the detection of liquid/solid weld pool interfaces, the determination of interface location, and effects of high temperature gradients near the molten zones on ultrasonic wave propagation are presented. Additional work required and problems associated with practical application of the techniques are discussed.

  17. Phased Arrays for Ultrasonic Investigations in Concrete Components

    Microsoft Academic Search

    Frank Mielentz

    2008-01-01

    An innovative application of ultrasonic testing using phased arrays for concrete components was investigated. A low frequency\\u000a ultrasonic phased array consisting of ten transducers was used. This configuration allowed the variation and control of the\\u000a sound field directivity during the measurement. The measurements were carried out on concrete test specimens using a scanning\\u000a laservibrometer in through transmission mode. The laboratory

  18. High temperature immersion type ultrasonic imaging probes

    NASA Astrophysics Data System (ADS)

    Rehman, A.-U.; Jen, C.-K.; Ihara, I.

    2001-04-01

    Ultrasonic probes for high temperature measurements in immersion are presented. These probes consist of piezoelectric transducers and buffer rods, are operated in the pulse-echo mode. The operating temperature is up to 215 °C and there is no need for a cooling system. For imaging purposes, one end of the clad buffer rod is attached with a piezoelectric transducer and the other end is machined into a semi-spherical concave shape that provides the focus. The operating frequency is 5 MHz. Ultrasonic images produced using mechanical raster scan and the measurements, when the probes are fully immersed in silicone oil at elevated temperatures, are presented. The importance of the signal-to-noise ratio in the pulse-echo measurement is discussed.

  19. Ultrasonic probes for high temperature immersion measurements

    NASA Astrophysics Data System (ADS)

    Rehman, A.-U.; Jen, C.-K.; Ihara, I.

    2001-03-01

    Ultrasonic probes for high temperature measurements in immersion are presented. These probes consist of piezoelectric transducers and buffer rods, and may be operated in the pulse echo mode. The probes can operate to temperatures as high as 215 °C without requiring a cooling system. For imaging purposes, one end of the clad buffer rod is machined into a semi-spherical concave shape, of which the purpose is to focus the ultrasound. The operating frequency is between 5 and 9 MHz. Ultrasonic images, produced using a mechanical raster scan with the probes fully immersed in silicone oil at elevated temperatures, are presented. The importance of the signal-to-noise ratio in the pulse-echo measurement is discussed.

  20. Embedded fiber optic ultrasonic sensors and generators

    NASA Astrophysics Data System (ADS)

    Dorighi, John F.; Krishnaswamy, Sridhar; Achenbach, Jan D.

    1995-04-01

    Ultrasonic sensors and generators based on fiber-optic systems are described. It is shown that intrinsic fiber optic Fabry-Perot ultrasound sensors that are embedded in a structure can be stabilized by actively tuning the laser frequency. The need for this method of stabilization is demonstrated by detecting piezoelectric transducer-generated ultrasonic pulses in the presence of low frequency dynamic strains that are intentionally induced to cause sensor drift. The actively stabilized embedded fiber optic Fabry-Perot sensor is also shown to have sufficient sensitivity to detect ultrasound that is generated in the interior of a structure by means of a high-power optical fiber that pipes energy from a pulsed laser to an embedded generator of ultrasound.

  1. Ultrasonic Bolt Gage

    NASA Technical Reports Server (NTRS)

    Gleman, Stuart M. (Inventor); Rowe, Geoffrey K. (Inventor)

    1999-01-01

    An ultrasonic bolt gage is described which uses a crosscorrelation algorithm to determine a tension applied to a fastener, such as a bolt. The cross-correlation analysis is preferably performed using a processor operating on a series of captured ultrasonic echo waveforms. The ultrasonic bolt gage is further described as using the captured ultrasonic echo waveforms to perform additional modes of analysis, such as feature recognition. Multiple tension data outputs, therefore, can be obtained from a single data acquisition for increased measurement reliability. In addition, one embodiment of the gage has been described as multi-channel, having a multiplexer for performing a tension analysis on one of a plurality of bolts.

  2. Low noise design of ultrasonic transducers

    Microsoft Academic Search

    A. Puttmer; N. Hoppe; P. Hauptmann

    1999-01-01

    Several industrial applications of ultrasonic techniques are limited by the signal-to-noise ratio (SNR). Examples include NDE or process monitoring. Transducers in these applications usually operate in the pulse-echo mode. Several transducers, especially those for high temperatures, use buffer rods. Interference of echo signal and noise causes errors of both amplitude and phase measurement of the detected echoes. This work aims

  3. Modal dispersion, pulse broadening and maximum transmission rate in GRIN optical fibers encompass a central dip in the core index profile

    NASA Astrophysics Data System (ADS)

    El-Diasty, Fouad; El-Hennawi, H. A.; El-Ghandoor, H.; Soliman, Mona A.

    2013-12-01

    Intermodal and intramodal dispersions signify one of the problems in graded-index multi-mode optical fibers (GRIN) used for LAN communication systems and for sensing applications. A central index dip (depression) in the profile of core refractive-index may occur due to the CVD fabrication processes. The index dip may also be intentionally designed to broaden the fundamental mode field profile toward a plateau-like distribution, which have advantages for fiber-source connections, fiber amplifiers and self-imaging applications. Effect of core central index dip on the propagation parameters of GRIN fiber, such as intermodal dispersion, intramodal dispersion and root-mean-square broadening, is investigated. The conventional methods usually study optical signal propagation in optical fiber in terms of mode characteristics and the number of modes, but in this work multiple-beam Fizeau interferometry is proposed as an inductive but alternative methodology to afford a radial approach to determine dispersion, pulse broadening and maximum transmission rate in GRIN optical fiber having a central index dip.

  4. High-resolution photoacoustic imaging with focused laser and ultrasonic beams

    E-print Network

    High-resolution photoacoustic imaging with focused laser and ultrasonic beams Fanting Kong,1 Y. C focusing transducer to obtain micron-resolution tissue images over a long working distance. The imager improvement in lateral and axial resolutions compared to the pulse-echo ultrasonic imaging technique

  5. Ultrasonic beam focusing through tissue inhomogeneities with a time reversal mirror: application to transskull therapy

    Microsoft Academic Search

    Jean-Louis Thomas; Mathias A. Fink

    1996-01-01

    Time reversal of ultrasonic fields allows a very efficient approach to focus pulsed ultrasonic waves through lossless inhomogeneous media. Time reversal mirrors (TRMs) are made of large transducer arrays, allowing the incident field to be sampled, time reversed, and reemitted. Time reversal method corrects for phase, amplitude, and even shape aberration and thus, is more efficient than time shift compensation

  6. Ultrasonic tissue characterization of prostate biopsy tissues by ultrasound speed microscope

    Microsoft Academic Search

    Hideki Tanoue; Yoshihiro Hagiwara; Kazuto Kobayashi; Yoshifumi Saijo

    2011-01-01

    Ultrasound speed microscope was developed for quantitative measurement of ultrasonic parameters of soft tissues. The system can measure the ultrasonic attenuation and sound speed in the tissue using fast Fourier transform of a single pulsed wave instead of burst waves used in conventional acoustic microscopy. Prostate biopsy tissues were formalin-fixed and sectioned approximately 5–6 ?m in thickness. They were mounted

  7. The aim of this project is to develop an ultrasonic device for parametric imaging of standing trees. The device is designed to perform both transmission and reflection measurements that can be therefore used for quantitative

    E-print Network

    Boyer, Edmond

    environments. Studies have demonstrated the effectiveness of acoustics in detecting/imaging trees' de- cay. The main commercial acoustic devices for tree assess- ment are essentially based on methods using low as possible. The parameter measured is the time-of-flight (travel time) of the ultrasonic wave between

  8. High voltage pulse conditioning

    DOEpatents

    Springfield, Ray M. (Sante Fe, NM); Wheat, Jr., Robert M. (Los Alamos, NM)

    1990-01-01

    Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

  9. Ultrasonic Communication Project, Phase 1, FY1999

    SciTech Connect

    Haynes, H.D.; Akerman, M.A.; Baylor, V.M.

    2000-06-01

    This Phase 1 project has been successful in identifying, exploring, and demonstrating methods for ultrasonic-based communication with an emphasis on the application of digital signal processing techniques. During the project, at the direction of the agency project monitor, particular attention was directed at sending and receiving ultrasonic data through air and through pipes that would be commonly found in buildings. Efforts were also focused on development of a method for transmitting computer files ultrasonically. New methods were identified and evaluated for ultrasonic communication. These methods are based on a technique called DFS. With DFS, individual alphanumeric characters are broken down into a sequence of bits, and each bit is used to generate a discrete ultrasonic frequency. Characters are then transmitted one-bit-at-a-time, and reconstructed by the receiver. This technique was put into practice through the development of LabVIEW{trademark}VIs. These VIs were integrated with specially developed electronic circuits to provide a system for demonstrating the transmission and reception/reconstruction of typed messages and computer files. Tests were performed to determine the envelope for ultrasound transmission through pipes (with and without water) versus through air. The practical aspects of connections, efficient electronics, impedance matching, and the effect of damping mechanisms were all investigated. These tests resulted in a considerable number of reference charts that illustrate the absorption of ultrasound through different pipe materials, both with and without water, as a function of distance. Ultrasound was found to be least attenuated by copper pipe and most attenuated by PVC pipe. Water in the pipe provides additional damping and attenuation of ultrasonic signals. Dramatic improvements are observed, however, in ultrasound signal strength if the transducers are directly coupled to the water, rather than simply attaching them to the outside of the pipe. A major accomplishment of this project was the development and integration of hardware and software into a fully functional ultrasonic communication system for demonstration purposes. The development of this system was a major deliverable of this project and has been successfully demonstrated to the program monitor. Major system considerations are discussed in this report, including signal conditioning electronics, speed and distance of transmission, triggering and noise filtering, and error checking. The methods employed by this system are believed to be capable of transmitting information over long distances (greater than 200 ft) under ideal conditions, and under extreme conditions if several improvements are made. Several improvements are suggested as follow-on work. Brief descriptions of these activities are given.

  10. Ultrasonic/Sonic Anchor

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Sherrit, Stewart

    2009-01-01

    The ultrasonic/sonic anchor (U/S anchor) is an anchoring device that drills a hole for itself in rock, concrete, or other similar material. The U/S anchor is a recent addition to a series of related devices, the first of which were reported in "Ultrasonic/Sonic Drill/Corers With Integrated Sensors"

  11. Review on ultrasonic machining

    Microsoft Academic Search

    T. B. Thoe; D. K. Aspinwall; M. L. H. Wise

    1998-01-01

    Ultrasonic machining is of particular interest for the cutting of non-conductive, brittle workpiece materials such as engineering ceramics. Unlike other non-traditional processes such as laser beam, and electrical discharge machining, etc., ultrasonic machining does not thermally damage the workpiece or appear to introduce significant levels of residual stress, which is important for the survival of brittle materials in service. The

  12. Ultrasonic properties of granular media saturated with DNAPL/water mixtures

    NASA Astrophysics Data System (ADS)

    Ajo-Franklin, J. B.; Geller, J. T.; Harris, J. M.

    2007-04-01

    We present the results of four experiments investigating the ultrasonic properties of granular materials partially saturated with trichloroethylene (TCE), a dense non-aqueous contaminant. P-wave velocity measurements were made under in situ effective stress conditions using a pulse transmission cell at ~250 kHz. Two synthetic samples and two natural aquifer cores were fully saturated with water and then subjected to an axial injection of TCE. The resulting measurements show reductions in P-wave velocity of up to 15% due to contaminant saturation. A theoretical model combining Gassmann fluid substitution and Hill's equation was used to estimate the effects of DNAPL saturation; this model underpredicted observed reductions in velocity at high TCE saturations. A linear relationship, expressed in terms of volumetric contaminant fraction, provided an excellent empirical fit to the laboratory measurements.

  13. Simple modeling of ultrasonic testing

    Microsoft Academic Search

    Takashi Furukawa; Kuzuhiro Date

    1994-01-01

    The ultrasonic wave generation and propagation were modeled to simulate an ultrasonic test. In order to make the wave generation model of an angle probe, sound pressure distribution of the wave generated from the probe was analyzed by the ultrasonic visualization method. Ray modeling is proposed for ultrasonic wave generation and propagation. In this method, the sound pressure was expressed

  14. Nondegenerate optical parametric chirped pulse amplifier

    DOEpatents

    Jovanovic, Igor; Ebbers, Christopher A.

    2005-03-22

    A system provides an input pump pulse and a signal pulse. A first dichroic beamsplitter is highly reflective for the input signal pulse and highly transmissive for the input pump pulse. A first optical parametric amplifier nonlinear crystal transfers part of the energy from the input pump pulse to the input signal pulse resulting in a first amplified signal pulse and a first depleted pump pulse. A second dichroic beamsplitter is highly reflective for the first amplified signal pulse and highly transmissive for the first depleted pump pulse. A second optical parametric amplifier nonlinear crystal transfers part of the energy from the first depleted pump pulse to the first amplified signal pulse resulting in a second amplified signal pulse and a second depleted pump pulse. A third dichroic beamsplitter receives the second amplified signal pulse and the second depleted pump pulse. The second depleted pump pulse is discarded.

  15. a Theoretical Study of the Kinetic Processes in a High-Power Xenon Chloride Excimer Laser Oscillator Driven by a Long Transmission Line Pulse Forming Network.

    NASA Astrophysics Data System (ADS)

    Wang, Yuh-Shuh

    1982-03-01

    The avalanche/self-sustained discharge rare gas halide (RGH) excimer lasers driven by a transmission line type pulse forming network (PFN) belong to a novel class of discharge pumped gas lasers operating in the visible and ultraviolet wavelengths efficiently. The kinetics in this class of lasers, however, has not yet been fully understood. Therefore, it seems essential at this point to study the characteristics of the discharge plasma in such a device and determine the major energy flow paths in the active media before one attempts to optimize the operating conditions or deduce the scaling rules. The work presented here is the theoretical modeling of the discharge pumped XeCl laser driven by a long transmission line (two way transit time, 200 nsec). The mathematical formulation consisting of the rate equations, the temperature equation, the circuit equation, and the Boltzmann equation governing the velocity and energy distributions of the free electrons is developed under the assumptions that the applied electric field strength is spatially uniform and the number densities of all important chemical species are spatially homogeneous in the discharge volume. These coupled non-linear differential equations are solved numerically by using the GBS extrapolation method simultaneously with the time evolution of the electron mole fraction during the transient discharge. The time-dependent electron velocity and energy distribution functions are obtained from the numerical solutions of the Boltzmann equation, with all elastic (including electron-electron), inelastic, attachment, recombination, and ionization collisions included, by a self-consistent iteration technique. The kinetic reactions involved in the XeCl laser using Ne/Xe/HCl and He/Xe/HCl mixtures are comprehensively examined. The results of this study reveal that the new processes. e + XeCl('*) (--->) Xe('*) + Cl('-),. e + XeCl (--->) Xe + Cl('-) or Xe + Cl + e,. are important and have to be included in the model. In addition, the rate constants of the processes. e + HCl(v=1) (--->) H + Cl('-),. XeCl + Ne,He (--->) Xe + Cl + Ne,He, and. h(nu) + XeCl('*) (--->) XeC('**). should be revised from the earlier published values. They are discussed in detail. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of school.) UMI.

  16. Method for the concurrent ultrasonic inspection of partially completed welds

    DOEpatents

    Johnson, John A. (Idaho Falls, ID); Larsen, Eric D. (Idaho Falls, ID); Miller, Karen S. (Idaho Falls, ID); Smartt, Herschel B. (Idaho Falls, ID); McJunkin, Timothy R. (Idaho Falls, ID)

    2002-01-01

    A method for the concurrent ultrasonic inspection of partially completed welds is disclosed and which includes providing a pair of transducers which are individually positioned on the opposite sides of a partially completed weld to be inspected; moving the transducers along the length of and laterally inwardly and outwardly relative to the partially completed weld; pulsing the respective transducers to produce an ultrasonic signal which passes through or is reflected from the partially completed weld; receiving from the respective transducers ultrasonic signals which pass through or are reflected from the partially completed welds; and analyzing the ultrasonic signal which has passed through or is reflected from the partially completed weld to determine the presence of any weld defects.

  17. Transmission Modulator/demodulator

    E-print Network

    Chen, Sheng

    ELEC3028 Digital Transmission -- MODEM S Chen Revision of Lecture 4 . We have discussed all basic components of MODEM -- Pulse shaping Tx/Rx filter pair -- Modulator/demodulator -- Bits map # symbols be compensated MODEM components pulse shaping Tx/Rx filter pair modulator/demodulator bits map # symbols

  18. Measurement of the spectral directivity of optoacoustic and ultrasonic transducers with a laser ultrasonic source.

    PubMed

    Conjusteau, André; Ermilov, Sergey A; Su, Richard; Brecht, Hans-Peter; Fronheiser, Matthew P; Oraevsky, Alexander A

    2009-09-01

    Comprehensive characterization of wideband ultrasonic transducers and specifically optoacoustic detectors is achieved through the analysis of their frequency response as a function of the incident angle. The tests are performed under well-defined, repeatable operating conditions. Backillumination of a blackened, acoustically matched planar surface with a short laser pulse creates an acoustic impulse which is used as a wideband ultrasonic source. Upon illumination with a short laser pulse, the bandwidth of our source shows a -6 dB point of 12 MHz and a low-frequency roll-off around 300 kHz. Using proprietary software, we examine thoroughly the planarity of the emitted wave front within a specified amplitude cutoff and phase incoherence. Analysis of the angular dependence of the frequency response yields invaluable directivity information about the detector under study: a necessary component toward accurate optoacoustic image reconstruction and quantitative tomography. The laser ultrasonic source we developed is the main feature of our directivity measurement setup. Due to its simplicity, it can easily be adapted to various calibration devices. This paper focuses on the development and characterization of the flatness and the bandwidth of our wideband ultrasonic source. PMID:19791945

  19. Three dimensional ultrasonic imaging

    SciTech Connect

    Thomas, G. H.; Benson, S.; Crawford, S.

    1993-03-01

    Ultrasonic nondestructive evaluation techniques interrogate components with high frequency acoustic energy. A transducer generates the acoustic energy and converts acoustic energy to electrical signals. The acoustic energy is reflected by abrupt changes in modulus and/or density which can be caused by a defect. Thus defects reflect the ultrasonic energy which is converted into electrical signals. Ultrasonic evaluation typically provides a two dimensional image of internal defects. These images are either planar views (C-scans) or cross-sectional views (B-scans). The planar view is generated by raster scanning an ultrasonic transducer over the component and capturing the amplitude of internal reflections. Depth information is generally ignored. The cross-sectional view is generated by scanning the transducer along a single line and capturing the amplitude and time of flight for each internal reflection. The amplitude and time of flight information is converted into an image of the cross section of the component where the scan was performed. By fusing the C-scan information with the B-scan information a three dimension image of the internal structure of the component can be produced. The three dimensional image can be manipulated by rotating and slicing to produce the optimal view of the internal structure. The high frequency ultrasonic energy requires a liquid coupling media and thus applications for imaging in liquid environments are well suited to ultrasonic techniques. Examples of potential ultrasonic imaging applications are: Inside liquid filled tanks, inside the human body, and underwater.

  20. Ultrasonic Imaging Techniques for Breast Cancer Detection

    NASA Astrophysics Data System (ADS)

    Goulding, N. R.; Marquez, J. D.; Prewett, E. M.; Claytor, T. N.; Nadler, B. R.

    2008-02-01

    Improving the resolution and specificity of current ultrasonic imaging technology is needed to enhance its relevance to breast cancer detection. A novel ultrasonic imaging reconstruction method is described that exploits classical straight-ray migration. This novel method improves signal processing for better image resolution and uses novel staging hardware options using a pulse-echo approach. A breast phantom with various inclusions is imaged using the classical migration method and is compared to standard computed tomography (CT) scans. These innovative ultrasonic methods incorporate ultrasound data acquisition, beam profile characterization, and image reconstruction. For an ultrasonic frequency of 2.25 MHz, imaged inclusions of approximately 1 cm are resolved and identified. Better resolution is expected with minor modifications. Improved image quality and resolution enables earlier detection and more accurate diagnoses of tumors thus reducing the number of biopsies performed, increasing treatment options, and lowering remission percentages. Using these new techniques the inclusions in the phantom are resolved and compared to the results of standard methods. Refinement of this application using other imaging techniques such as time-reversal mirrors (TRM), synthetic aperture focusing technique (SAFT), decomposition of the time reversal operator (DORT), and factorization methods is also discussed.

  1. Ultrasonic Digital Communication System for a Steel Wall Multipath Channel: Methods and Results

    SciTech Connect

    TL Murphy

    2006-02-16

    As of the development of this thesis, no commercially available products have been identified for the digital communication of instrumented data across a thick ({approx} 6 n.) steel wall using ultrasound. The specific goal of the current research is to investigate the application of methods for digital communication of instrumented data (i.e., temperature, voltage, etc.) across the wall of a steel pressure vessel. The acoustic transmission of data using ultrasonic transducers prevents the need to breach the wall of such a pressure vessel which could ultimately affect its safety or lifespan, or void the homogeneity of an experiment under test. Actual digital communication paradigms are introduced and implemented for the successful dissemination of data across such a wall utilizing solely an acoustic ultrasonic link. The first, dubbed the ''single-hop'' configuration, can communicate bursts of digital data one-way across the wall using the Differential Binary Phase-Shift Keying (DBPSK) modulation technique as fast as 500 bps. The second, dubbed the ''double-hop'' configuration, transmits a carrier into the vessel, modulates it, and retransmits it externally. Using a pulsed carrier with Pulse Amplitude Modulation (PAM), this technique can communicate digital data as fast as 500 bps. Using a CW carrier, Least Mean-Squared (LMS) adaptive interference suppression, and DBPSK, this method can communicate data as fast as 5 kbps. A third technique, dubbed the ''reflected-power'' configuration, communicates digital data by modulating a pulsed carrier by varying the acoustic impedance at the internal transducer-wall interface. The paradigms of the latter two configurations are believed to be unique. All modulation methods are based on the premise that the wall cannot be breached in any way and can therefore be viably implemented with power delivered wirelessly through the acoustic channel using ultrasound. Methods, results, and considerations for future research are discussed herein.

  2. Transmission Modulator/demodulator --

    E-print Network

    Chen, Sheng

    ELEC3028 Digital Transmission -- MODEM S Chen Revision of Lecture 3 . Modulator -- Carrier recovery and timing recovery This lecture: bits map # symbols MODEM components pulse shaping Tx several bits into a symbol? 40 #12; ELEC3028 Digital Transmission -- MODEM S Chen Bits to Symbols

  3. The application research of laser ultrasonic technique used in testing compound material

    NASA Astrophysics Data System (ADS)

    Xu, Jun; Kong, Lingjian; Gu, Xiaofei; Luo, Jijun; Hou, Xun

    2005-01-01

    The principles of laser ultrasonic generation and measurements with pulsed laser are presented. There are two kinds of means to actuate ultrasonic pulse: elasticity actuating and ablation actuating. The progress in laser ultrasonic about laser ultrasound generation, detection, propagation and its applications is introduced briefly. Applications in the field of Non-Destructive Testing (NDT) are reviewed. In the field of Non-Destructive Testing, according to the principle, the laser ultrasonic testing system consists of laser system, laser interferometer, photoelectric detector and receiving system with signal amplifier. Thus, long-range and non-contact on-line detection of ultrasonic testing system was realized. In view of some of the problems, the developing trends of such techniques are analyzed.

  4. Ultrasonic drilling apparatus

    DOEpatents

    Duran, Edward L. (Santa Fe, NM); Lundin, Ralph L. (Los Alamos, NM)

    1989-01-01

    Apparatus attachable to an ultrasonic drilling machine for drilling deep holes in very hard materials, such as boron carbide, is provided. The apparatus utilizes a hollow spindle attached to the output horn of the ultrasonic drilling machine. The spindle has a hollow drill bit attached at the opposite end. A housing surrounds the spindle, forming a cavity for holding slurry. In operation, slurry is provided into the housing, and into the spindle through inlets while the spindle is rotating and ultrasonically reciprocating. Slurry flows through the spindle and through the hollow drill bit to cleanse the cutting edge of the bit during a drilling operation.

  5. Ultrasonic liquid level detector

    DOEpatents

    Kotz, Dennis M. (North Augusta, SC); Hinz, William R. (Augusta, GA)

    2010-09-28

    An ultrasonic liquid level detector for use within a shielded container, the detector being tubular in shape with a chamber at its lower end into which liquid from in the container may enter and exit, the chamber having an ultrasonic transmitter and receiver in its top wall and a reflector plate or target as its bottom wall whereby when liquid fills the chamber a complete medium is then present through which an ultrasonic wave may be transmitted and reflected from the target thus signaling that the liquid is at chamber level.

  6. Laser ultrasonics: Current research needs

    SciTech Connect

    Wagner, J.W. (Johns Hopkins Univ., Baltimore, MD (USA). Center for Nondestructive Evaluation)

    1990-09-26

    Laser-ultrasonics refers to a range of technologies involving the use of laser electrooptical systems both to generate and to detect ultrasonic signals in and on materials and structures. Such systems have been developed to permit classical ultrasonic measurements for materials characterization and defect identification and measurement. From the point of view of one concerned with practical applications of ultrasonic inspection and measurement methods, laser-ultrasonic systems offer the flexibility which, in principle, should permit remote ultrasonic measurements to be performed on objects at elevated temperatures or in hostile environments. Laser-ultrasonic systems can be designed and constructed with extremely wide and flat detection bandwidth so that ultrasonic vibrational displacements can be recorded with high fidelity. In addition, there is no mechanical loading of the surface to damp, absorb, or otherwise distort the propagating acoustic energy. This feature has been used to great advantage in performing ultrasonic measurements in thin plates and films. In spite of the great advantages offered by laser-ultrasonics, there are severe limitations which restrict its application. In fact, based upon the performance of current state-of-the-art laser-ultrasonic systems, it is almost always more advantageous to use conventional ultrasonic transduction methods, if possible for a given application, than it is to apply laser-ultrasonics. In short, the main reason leading to this conclusion is the poor system detection sensitivity of laser-ultrasonic systems compared with piezoelectric transducer systems. The ramifications of this limited sensitivity are many.

  7. Detection and characterization of impact damage in composite panels using multiple ultrasonic methods

    NASA Astrophysics Data System (ADS)

    Williams, Westin B.; Michaels, Thomas E.; Michaels, Jennifer E.

    2015-03-01

    Abrupt impacts to solid laminate composite panels often produce internal damage that is not visible on the impacted surface. It is important that such damage be promptly detected since it can compromise the strength of composite structures. Ultrasonic C-scan imaging has been extensively used to detect and characterize impact damage using both pulse-echo and through-transmission methods. More recently developed guided wave imaging methods, such as sparse array imaging with baseline subtraction and wavefield imaging, have also been used to successfully detect damage in composite panels; however, their performance is generally not comparable to that achieved with bulk wave C-scans. For this study, various force impacts were used to create defect conditions ranging from barely detectable damage to extensive damage that was visible on the impact surface. Guided wave signals were recorded from an attached sparse transducer array before and after the impacts, and panels were scanned using both conventional ultrasonic C-scan methods and acoustic wavefield imaging. For each method, imaging results are presented and compared in terms of their ability to locate and characterize impact damage.

  8. Simulation of ultrasonic lamb wave generation, propagation and detection for a reconfigurable air coupled scanner.

    PubMed

    Dobie, Gordon; Spencer, Andrew; Burnham, Kenneth; Pierce, S Gareth; Worden, Keith; Galbraith, Walter; Hayward, Gordon

    2011-04-01

    A computer simulator, to facilitate the design and assessment of a reconfigurable, air-coupled ultrasonic scanner is described and evaluated. The specific scanning system comprises a team of remote sensing agents, in the form of miniature robotic platforms that can reposition non-contact Lamb wave transducers over a plate type of structure, for the purpose of non-destructive evaluation (NDE). The overall objective is to implement reconfigurable array scanning, where transmission and reception are facilitated by different sensing agents which can be organised in a variety of pulse-echo and pitch-catch configurations, with guided waves used to generate data in the form of 2-D and 3-D images. The ability to reconfigure the scanner adaptively requires an understanding of the ultrasonic wave generation, its propagation and interaction with potential defects and boundaries. Transducer behaviour has been simulated using a linear systems approximation, with wave propagation in the structure modelled using the local interaction simulation approach (LISA). Integration of the linear systems and LISA approaches are validated for use in Lamb wave scanning by comparison with both analytic techniques and more computationally intensive commercial finite element/difference codes. Starting with fundamental dispersion data, the paper goes on to describe the simulation of wave propagation and the subsequent interaction with artificial defects and plate boundaries, before presenting a theoretical image obtained from a team of sensing agents based on the current generation of sensors and instrumentation. PMID:21094966

  9. Ultrasonic Behaviour of Liquid Crystalline Mixture of Octadecanol and Cholestrol

    Microsoft Academic Search

    S. K. Kor; A. K. Srivastava

    1985-01-01

    The paper reports experimental results of ultrasonic absorption and velocity in a liquid crystalline mixture of ocatadecanol and cholestrol with different concentrations and its behaviour with temperature specially near transition temperature. The absorption has been measured using the pulse technique and the velocity with the help of an acoustic interferometer both at a single frequency of 2 MHz. The temperature

  10. Capacitive Micromachined Ultrasonic Transducers (CMUTs) for Photoacoustic Imaging

    Microsoft Academic Search

    Srikant Vaithilingam; Ira O. Wygant; P Aulina S. Kuo; Xuefeng Zhuang; Omer Oralkan; Peter D. Olcott; Butrus T. Khuri-yakub

    ABSTRACT In photoacoustic (optoacoustic) medical imaging, short laser pulses irradiate absorbing structures found in tissue, such as blood vessels, causing brief thermal expansions that in turn generate ultrasound waves. These ultrasound waves which correspond to the optical absorption distribution were imaged using a two-dimensional array of capacitive micromachined ultrasonic transducers (CMUTs). Advantages of CMUT technology for photoacoustic imaging include the

  11. Optoacoustic imaging using two-dimensional ultrasonic detection

    Microsoft Academic Search

    Guenther Paltauf; Heinz Schmidt-Kloiber; Kornel P. Koestli; Martin Frenz; Heinz P. Weber

    2000-01-01

    Optoacoustic imaging uses thermoelastic waves generated by short laser pulses to localize structures with preferential light absorption inside a material. The acoustic waves are directly generated in absorbing structures and are detected outside the sample with a wide-band ultrasonic transducer. Image reconstruction is usually done by backprojection of temporal ultrasound signals that are taken at different positions. As an alternative,

  12. COMPARISON OF IMAGING CAPABILITIES BETWEEN ULTRASONICS AND RADIOGRAPHY

    E-print Network

    Avenue, N.W. Washington, D.C. 20460 Prepared by Department of Sensor Systems and NDE Technology Division by Department of Sensor Systems and NDE Technology Division of Applied Physics Southwest Research Institute of the internal working of the ultrasonic imaging cameras developed by Imperium, Inc., in (a) pulse-echo mode

  13. Nonlinear Angle Beam Ultrasonic Evaluation of Adhesive Bonds

    Microsoft Academic Search

    S. I. Rokhlin; L. Wang; A. Baltazar; V. A. Yakovlev; L. Adler

    2003-01-01

    We have developed an experimental method incorporating high frequency pulsed angle beam ultrasonic measurements under low frequency vibration of bonded structures utilizing parametric\\/nonlinear mixing between high and low frequencies. We have demonstrated that the effect of environmental degradation of adhesive bonds can be detected by this method. It is shown that good quality (undamaged) bonds do not exhibit dependence of

  14. Ultrasonic-Assisted Synthesis of Graphite-Reinforced Al Matrix Nanocomposites

    NASA Astrophysics Data System (ADS)

    Christy Roshini, P.; Nagasivamuni, B.; Raj, Baldev; Ravi, K. R.

    2015-06-01

    A novel approach to produce Al-2 vol.% graphite nanocomposites using micron-sized graphite particles has been reported using conventional stir casting technique combined with ultrasonic treatment. Microstructural observations indicate that the visible agglomerations and porosities are significantly reduced after ultrasonic treatment. Transmission electron microscopy studies of ultrasonic-treated composites reveal that the size of the graphite particles is reduced substantially and its morphology is transformed into flake type structures. The width of the graphite flakes is reduced markedly with the increase in ultrasonic processing time and it is found to be in the range of 100-120 nm with an aspect ratio of 8.83 after 5 min of ultrasonication. Added to that, considerable improvement in the hardness values are noted for ultrasonic-treated Al-2 vol.% graphite composites when compared to conventional untreated composites. The mechanism behind the significant reduction in graphite particle size and porosity, uniform distribution of graphite particles and hardness increments are discussed.

  15. Ultrasonic-Assisted Synthesis of Graphite-Reinforced Al Matrix Nanocomposites

    NASA Astrophysics Data System (ADS)

    Christy Roshini, P.; Nagasivamuni, B.; Raj, Baldev; Ravi, K. R.

    2015-04-01

    A novel approach to produce Al-2 vol.% graphite nanocomposites using micron-sized graphite particles has been reported using conventional stir casting technique combined with ultrasonic treatment. Microstructural observations indicate that the visible agglomerations and porosities are significantly reduced after ultrasonic treatment. Transmission electron microscopy studies of ultrasonic-treated composites reveal that the size of the graphite particles is reduced substantially and its morphology is transformed into flake type structures. The width of the graphite flakes is reduced markedly with the increase in ultrasonic processing time and it is found to be in the range of 100-120 nm with an aspect ratio of 8.83 after 5 min of ultrasonication. Added to that, considerable improvement in the hardness values are noted for ultrasonic-treated Al-2 vol.% graphite composites when compared to conventional untreated composites. The mechanism behind the significant reduction in graphite particle size and porosity, uniform distribution of graphite particles and hardness increments are discussed.

  16. A Novel Application of Ultrasonic Imaging to Study Smoldering Combustion

    NASA Technical Reports Server (NTRS)

    Tse, S. D.; Anthenien, R. A.; Fernandez-Pello, A. Carlos; Miyasaka, K.

    1997-01-01

    An ultrasonic imaging technique has been developed to examine the propagation of a smolder reaction within a porous combustible material. The technique provides information about the location of a propagating smolder front, as well as line-of-sight average permeability variations of the smoldering material. The method utilizes the observation that transmission of an ultrasonic signal through a porous material increases with permeability. Since a propagating smolder reaction leaves behind char with a higher permeability than the original material, ultrasound transmission can be employed to monitor smolder progress. The technique can also be used to track the char evolution as it continues to react. Experiments are presented where the technique is applied to smoldering combustion in a two-dimensional geometry. The results have furthered the understanding of two-dimensional smolder, especially in identifying the controlling mechanisms leading to the transition from smoldering to flaming. The applicability of ultrasonic tomography to smoldering combustion has also been investigated.

  17. Error-eliminating rapid ultrasonic firing

    DOEpatents

    Borenstein, J.; Koren, Y.

    1993-08-24

    A system for producing reliable navigation data for a mobile vehicle, such as a robot, combines multiple range samples to increase the confidence'' of the algorithm in the existence of an obstacle. At higher vehicle speed, it is crucial to sample each sensor quickly and repeatedly to gather multiple samples in time to avoid a collision. Erroneous data is rejected by delaying the issuance of an ultrasonic energy pulse by a predetermined wait-period, which may be different during alternate ultrasonic firing cycles. Consecutive readings are compared, and the corresponding data is rejected if the readings differ by more than a predetermined amount. The rejection rate for the data is monitored and the operating speed of the navigation system is reduced if the data rejection rate is increased. This is useful to distinguish and eliminate noise from the data which truly represents the existence of an article in the field of operation of the vehicle.

  18. Pulse stretcher

    DOEpatents

    Horton, James A. (Livermore, CA)

    1994-01-01

    Apparatus (20) for increasing the length of a laser pulse to reduce its peak power without substantial loss in the average power of the pulse. The apparatus (20) uses a White cell (10) having a plurality of optical delay paths (18a-18d) of successively increasing number of passes between the field mirror (13) and the objective mirrors (11 and 12). A pulse (26) from a laser (27) travels through a multi-leg reflective path (28) between a beam splitter (21) and a totally reflective mirror (24) to the laser output (37). The laser pulse (26) is also simultaneously injected through the beam splitter (21) to the input mirrors (14a-14d) of the optical delay paths (18a-18d). The pulses from the output mirrors (16a-16d) of the optical delay paths (18a-18d) go simultaneously to the laser output (37) and to the input mirrors ( 14b-14d) of the longer optical delay paths. The beam splitter (21) is 50% reflective and 50% transmissive to provide equal attenuation of all of the pulses at the laser output (37).

  19. Detonator comprising a nonlinear transmission line

    DOEpatents

    Elizondo-Decanini, Juan M

    2014-12-30

    Detonators are described herein. In a general embodiment, the detonator includes a nonlinear transmission line that has a variable capacitance. Capacitance of the nonlinear transmission line is a function of voltage on the nonlinear transmission line. The nonlinear transmission line receives a voltage pulse from a voltage source and compresses the voltage pulse to generate a trigger signal. Compressing the voltage pulse includes increasing amplitude of the voltage pulse and decreasing length of the voltage pulse in time. An igniter receives the trigger signal and detonates an explosive responsive to receipt of the trigger signal.

  20. Ultrasonic characterization of granites obtained from industrial quarries of Extremadura (Spain).

    PubMed

    del Río, L M; López, F; Esteban, F J; Tejado, J J; Mota, M; González, I; San Emeterio, J L; Ramos, A

    2006-12-22

    The industry of ornamental rocks, such as granites, represents one of the most important industrial activities in the region of Extremadura, SW Spain. A detailed knowledge of the intrinsic properties of this natural stone and its environmental evolution is a required goal in order to fully characterize its quality. In this work, two independent NDT acoustic techniques have been used to measure the acoustic velocity of longitudinal waves in different prismatic granitic-samples of industrial quarries. A low-frequency transceiver set-up, based on a high-voltage BPV Steinkamp instrument and two 50 kHz probes, has been used to measure pulse travel times by ultrasonic through-transmission testing. In complementary fashion, an Erudite MK3 test equipment with an electromagnetic vibrator and two piezoelectric sensors has also been employed to measure ultrasonic velocity by means of a resonance-based method, using the same types of granite varieties. In addition, a comprehensive set of physical/mechanical properties have also been analyzed, according to Spanish regulations in force, by means of alternative methods including destructive techniques such as strength, porosity, absorption, etc. A large number of samples, representing the most important varieties of granites from quarries of Extremadura, have been analyzed using the above-mentioned procedures. Some results obtained by destructive techniques have been correlated with those found using ultrasonic techniques. Our experimental setting allowed a complementary characterization of granite samples and a thorough validation of the different techniques employed, thus providing the industry of ornamental rocks with a non-destructive tool that will facilitate a more detailed insight on the properties of the rocks under study. PMID:16814343

  1. Ultrasonic Velocities in Lightly-Loaded Natural and Synthetic Granular Media*

    NASA Astrophysics Data System (ADS)

    Du Frane, W.; Toffelmier, D.; Carlson, S.; Bonner, B.; Berge, P.

    2002-12-01

    The seismic properties of near surface soils are of interest for a variety of problems, including pore fluid identification and tracking, wave propagation modeling, geotechnical site characterization, static corrections for reflection seismology, and locating underground objects. Ultrasonic velocities increase rapidly when a granular material is loaded as contact stress and area and coordination number of grain contacts increase. Porosity, grain size and distribution, grain shape, and mineralogy all play a role in determining this nonlinear response. We adapted the ultrasonic pulse transmission method to measure compressional (P) and shear (S) wave velocities at ultrasonic frequencies (100-500 kHz) for lightly loaded artificial soils (to 0.1 MPa maximum). Samples were fabricated from Ottawa sand (some with montmorillonite added), Santa Cruz beach aggregate, artificial glass beads, and alumina spheres. All materials were characterized with the SEM before the experiments. We focused on packing, mineralogy, and hysteretic effects in our study and found that compressional velocities vary from ~200 to ~700 m/s over the narrow loading range investigated as a result of these effects. In light cyclic loading of pure Ottawa sand we observed hysteretic effects in the shear mode velocity, implicating sticking of the grains. Our measurements demonstrate a cubic relationship between stress and compressional wave velocity for pure quartz sand, as predicted by Hertzian contact theory when grain roughness is incorporated. The sand/clay mixtures were found to have very different properties from pure sand. The clay bridged sand grains creating more area at the contacts and higher sound speeds over the narrow loading range, but suppressed the strong nonlinear behavior predicted by Hertzian contact theory. *This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract number W-7405-ENG-48 and was supported specifically by the Environmental Management Science Program of the Office of Environmental Management and the Office of Energy Research.

  2. Magnetization changes by superimposed stress pulses

    NASA Technical Reports Server (NTRS)

    Onengut, D.; Schroder, K.

    1979-01-01

    The magnetization of a BiMn alloy with ferromagnetic inclusions changes at constant magnetic field, if the sample is subjected to ultrasonic pulses. The magnetization changes can be described on the basis of the Stoner-Wohlfarth theory of coherent rotation. It is possible to change the magnetization in selected volume elements by superimposing short pulses in those volume elements.

  3. Ultrasonic evaluation of high-voltage circuit boards

    NASA Technical Reports Server (NTRS)

    Klima, S. J.; Riley, T. J.

    1978-01-01

    Ultrasonic transmission technique, using reflector plate, indicates resistance to corona formation. Technique is useful as tool for mapping specific panels to permit selecting best areas of laminate for circuit board use. Procedure is relatively safe, fast, inexpensive, and uses commercially-available equipment.

  4. Ultrasonic transducers for cure monitoring: design, modelling and validation

    Microsoft Academic Search

    Francesca Lionetto; Francesco Montagna; Alfonso Maffezzoli

    2011-01-01

    The finite element method (FEM) has been applied to simulate the ultrasonic wave propagation in a multilayered transducer, expressly designed for high-frequency dynamic mechanical analysis of polymers. The FEM model includes an electro-acoustic (active element) and some acoustic (passive elements) transmission lines. The simulation of the acoustic propagation accounts for the interaction between the piezoceramic and the materials in the

  5. Structural improvement for solder joint failure in ultrasonic plastic assembly

    Microsoft Academic Search

    Jie Shen; Xianlong Jin

    2008-01-01

    This paper presents a method of structural dynamic analysis with finite element method to identify the cause failure of solder joint caused by the vibration of ultrasonic welding. In this method, explicit FE method and its contact algorithm are used to simulate the energy transmission from vibrational energy to internal energy under some assumptions. Therefore, firstly, its feasibility is verified

  6. Surface nanocrystallization of iron induced by ultrasonic shot peening

    Microsoft Academic Search

    N. R. Tao; M. L. Sui; J. Lu; K Lua

    1999-01-01

    A nanocrystalline surface layer was fabricated on a pure Fe plate by using an ultrasonic shot peening (USSP) technique. The USSP induced surface nanocrystallization products were characterized by means of X-ray diffraction (XRD) and transmission electron microscope (TEM). Experimental evidences showed that after USSP treatments, the initial coarse-grained structure in the surface layer was refined into equiaxed ultrafine grains (about

  7. Non-invasive and non-destructive ultrasonic technique for the detection of microbial contamination in packed UHT milk

    Microsoft Academic Search

    L. Elvira; L. Sampedro; J. Matesanz; Y. Gómez-Ullate; P. Resa; J. R. Iglesias; F. J. Echevarría; F. Montero de Espinosa

    2005-01-01

    An eight-channel ultrasonic device was developed to detect microorganism growth in UHT milk contained in carton-like packages without opening the packs. The system analyses automatically the amplitude and the delay of an ultrasonic pulse passing through packed UHT processed milk, being the coupling between the transducers and the packs accomplished in dry conditions. Changes in these parameters produced by different

  8. Flexible ultrasonic array system for inspecting thick composite structures

    NASA Astrophysics Data System (ADS)

    Frankle, Robert S.; Rose, Douglas N.

    1995-06-01

    Composite materials, which have commonly been used in recreational boats, are now being applied to more challenging marine applications. The high specific stiffness and strength of composites translates into increased range and payload. Composites offer the added benefits of corrosion and erosion resistance, fatigue and wear resistance, reduced signature, and reduced maintenance and life cycle costs as compared to traditional metallic structures. Although ultrasonic techniques are typically used to inspect composite structures, thick composites, such as those used in marine applications, are difficult to inspect with ordinary ultrasonic methods. An ultrasonic inspection system is being developed for the US Army to inspect thick composite materials for future armored vehicles. This system is an extension of the existing PARIS flexible array ultrasonic inspection system, which was originally developed for inspecting thin composite aircraft structures. The extension is designed to increase ultrasonic penetration by 1) fabricating an array that operates at lower frequency and higher voltage, and 2) employing a synthetic pulse technique. The flexible array can rapidly inspect large areas and produce images of the inspection results that are easy to interpret. This paper describes the ultrasonic inspection system and presents examples of inspection results from both thick and thin composite materials.

  9. Parallax, Inc. PING))) Ultrasonic Distance Sensor (#28015) v1.3 6/13/2006 Page 1 of 13

    E-print Network

    Grantner, Janos L.

    an output pulse that corresponds to the time required for the burst echo to return to the sensor microcontroller (trigger pulse), the sensor emits a short 40 kHz (ultrasonic) burst. This burst travels through))) sensor provides an output pulse to the host that will terminate when the echo is detected, hence

  10. Photoconductive circuit element pulse generator

    DOEpatents

    Rauscher, Christen (Alexandria, VA)

    1989-01-01

    A pulse generator for characterizing semiconductor devices at millimeter wavelength frequencies where a photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test.

  11. Focused high frequency needle transducer for ultrasonic imaging and trapping

    PubMed Central

    Hsu, Hsiu-Sheng; Zheng, Fan; Li, Ying; Lee, Changyang; Zhou, Qifa; Kirk Shung, K.

    2012-01-01

    A miniature focused needle transducer (<1?mm) was fabricated using the press-focusing technique. The measured pulse-echo waveform showed the transducer had center frequency of 57.5 MHz with 54% bandwidth and 14?dB insertion loss. To evaluate the performance of this type of transducer, invitro ultrasonic biomicroscopy imaging on the rabbit eye was obtained. Moreover, a single beam acoustic trapping experiment was performed using this transducer. Trapping of targeted particle size smaller than the ultrasonic wavelength was observed. Potential applications of these devices include minimally invasive measurements of retinal blood flow and single beam acoustic trapping of microparticles. PMID:22865930

  12. Focused high frequency needle transducer for ultrasonic imaging and trapping

    NASA Astrophysics Data System (ADS)

    Hsu, Hsiu-Sheng; Zheng, Fan; Li, Ying; Lee, Changyang; Zhou, Qifa; Kirk Shung, K.

    2012-07-01

    A miniature focused needle transducer (<1 mm) was fabricated using the press-focusing technique. The measured pulse-echo waveform showed the transducer had center frequency of 57.5 MHz with 54% bandwidth and 14 dB insertion loss. To evaluate the performance of this type of transducer, invitro ultrasonic biomicroscopy imaging on the rabbit eye was obtained. Moreover, a single beam acoustic trapping experiment was performed using this transducer. Trapping of targeted particle size smaller than the ultrasonic wavelength was observed. Potential applications of these devices include minimally invasive measurements of retinal blood flow and single beam acoustic trapping of microparticles.

  13. American Institute of Aeronautics and Astronautics Embedded Ultrasonic Structural Radar with Piezoelectric Wafer

    E-print Network

    Giurgiutiu, Victor

    a relatively large ultrasonic transducer. Snell's law ensures mode conversion at the interface, hence and passive modes. In active mode, PWAS generated Lamb waves that can be used for damage detection through pulse-echo or pitch-catch techniques. An efficient application of the pulse-echo method with PWAS

  14. Effect of lateral electronic diffusion on acoustic diffraction in picosecond ultrasonics

    Microsoft Academic Search

    Thomas Dehoux; Nikolay Chigarev; Clément Rossignol; Bertrand Audoin

    2008-01-01

    A diffracted picosecond ultrasonic field is generated by a 100 fs laser pulse focused onto a spot with diameter less than 1mum . As the pulse duration is shorter than the relaxation time of the electrons, the microscopic evolutions must be accounted for in metals. Following the absorption of the laser energy transported by the photons, electrons diffuse in all

  15. High-spatial-resolution digital system for ultrasonic imaging. Final technical report

    SciTech Connect

    McDonald, J.F.; Das, P.K.; Laprade, K.C.; Hidalgo, C.J.; Goekjian, K.S.

    1986-02-01

    In recent years, the authors have investigated some of the fundamental theoretical physical limitations imposed on ultrasonic array performance. This has led to the extensive study of energy trapping as one means of enhancing the spatial confinement of element radiation in the array. In this report, they describe a system designed to explore the quality of the images produced by practical trapped energy mode, hybrid trapped energy mode, and other types of arrays. The system implements a 256-channel parallel set of A/D and D/A converters for attachment to an arbitrary array. All 256 channels operate simultaneously at a maximum sampling frequency of 10 MHz. Hence, the total throughput of signal samples reaches 2.5 billion samples per second in a burst mode. The multiple-ported DRAM memory has 1x10/sup 6/ bytes of local high-speed storage. Since all of the input and output signals are in digital form, a wide variety of image-processing techniques can be employed. For example, from a single pulse, it is possible to reconstruct the two-dimensional hologram of the ultrasonic imaging using fast digital hardware. The images can also be prepared by pulse-echo techniques using the same system. Transmission from one portion of the array and monitoring the signal in another portion simultaneously to detect interelement coupling is possible. In this way, all of the key array parameters can be controlled and calibrated. Because of the D/A capability of the system, various signals can be transmitted from each array element, thereby permitting focusing and design of optimum probing signals.

  16. Intense Microwave Pulses III

    Microsoft Academic Search

    Howard E. Brandt

    1995-01-01

    The goal of the Intense Microwave Pulses III conference was to present and critically assess new and innovative ideas, together with recent advances, in the generation and transmission of intense microwave pulses. Significant advances were reported on Super-Reltron source development. Also presented were numerous results of research on high-power klystron oscillators and amplifiers. Results of preliminary experimental studies were presented

  17. Ultrasonic Stir Welding

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy

    2015-01-01

    NASA Marshall Space Flight Center (MSFC) developed Ultrasonic Stir Welding (USW) to join large pieces of very high-strength metals such as titanium and Inconel. USW, a solid-state weld process, improves current thermal stir welding processes by adding high-power ultrasonic (HPU) energy at 20 kHz frequency. The addition of ultrasonic energy significantly reduces axial, frictional, and shear forces; increases travel rates; and reduces wear on the stir rod, which results in extended stir rod life. The USW process decouples the heating, stirring, and forging elements found in the friction stir welding process allowing for independent control of each process element and, ultimately, greater process control and repeatability. Because of the independent control of USW process elements, closed-loop temperature control can be integrated into the system so that a constant weld nugget temperature can be maintained during welding.

  18. Laser ultrasonic generation at the surface of a liquid metal

    SciTech Connect

    Walter, J.B.; Telschow, K.L. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Conant, R.J. [Montana State Univ., Bozeman, MT (United States). Dept. of Mechanical Engineering

    1995-01-01

    The noncontacting nature of laser-based ultrasonic measurement has made it attractive in many applications. While most applications thus far involve solid samples, molten metals encountered in some stages of metal processing appear well suited to this technique. Possible applications for liquid metals include locating and characterizing the liquid/solid interface; characterizing a surface layer, contaminant, or alloying constituent; and measuring the temperature of the sample surface or bulk. This work aimed to characterize laser generation of ultrasound in liquid metals to facilitate the development of techniques for these applications. This paper describes measurements of the angular distribution and energy dependence of laser-generated ultrasound in mercury at ambient temperature. Mercury was chosen as the model liquid metal because it is liquid at room temperature, and so should have negligible temperature gradients beyond those produced in the laser generation process, and because it exhibits a very shallow optical penetration depth. Brief descriptions about the theory of laser generation by thermoelastic and ablation sources at the surface of a liquid metal are included. Both thermoelastic expansion and ablation cause similar ultrasound generation in liquid metals when laser generated ultrasonic pulses are directed perpendicular to the surface of liquid metals. The ultrasonic pulse amplitude is proportional to the absorbed laser pulse energy for both mechanisms. The simple threshold model presented for ablation describes the transition from thermoelastic generation with the model`s two parameters being material dependent. For mercury, ablation produces about 100 times larger ultrasonic pulse amplitudes than thermoelastic expansion and has a threshold of about 6 MW/square cm. Molten metals offer a good medium for studying ablation, since the surface is always refreshed and ablation, at least for mercury, dominates ultrasonic generation above the threshold.

  19. Ultrasonic thermoacoustic energy converter.

    PubMed

    Flitcroft, Myra; Symko, Orest G

    2013-03-01

    Thermoacoustic prime movers have been developed for operation in the low ultrasonic frequency range by scaling down the device size. The developed engines operate at frequencies up to 23 kHz. They are self-sustained oscillators whose dimensions scale inversely with operating frequency. The smallest one being 3.4 mm long with a 1mm diameter bore, i.e. the engine inner volume of 2.67 mm(3). The generated sound levels reached intensities in the range of 143-150 dB in the low ultrasonic range. The miniaturization of thermoacoustic engines will lead to the development of device arrays. PMID:23218928

  20. Ultrasonic Processing of Materials

    SciTech Connect

    Meek, Thomas T.; Han, Qingyou; Jian, Xiaogang; Xu, Hanbing

    2005-06-30

    The purpose of this project was to determine the impact of a new breakthrough technology, ultrasonic processing, on various industries, including steel, aluminum, metal casting, and forging. The specific goals of the project were to evaluate core principles and establish quantitative bases for the ultrasonc processing of materials, and to demonstrate key applications in the areas of grain refinement of alloys during solidification and degassing of alloy melts. This study focussed on two classes of materials - aluminum alloys and steels - and demonstrated the application of ultrasonic processing during ingot casting.

  1. Ultrasonic shear wave velocity in CLF/CMT graphite from room temperature to 2000/sup 0/F

    SciTech Connect

    Gieske, J.H.

    1980-11-01

    The temperature dependence of the ultrasonic shear velocity in CLF/CMT graphite was determined from room temperature to 2000/sup 0/F using a pulse-echo technique. Data are presented for five 0.75-inch-diameter specimens all machined from the same CLF/CMT billet. Plots of ultrasonic pulse-echo radial and axial scans of the billet which characterize the material property uniformity of the billet are also given.

  2. Differential pulse code modulation

    NASA Technical Reports Server (NTRS)

    Herman, C. F. (inventor)

    1976-01-01

    A differential pulse code modulation (DPCM) encoding and decoding method is described along with an apparatus which is capable of transmission with minimum bandwidth. The apparatus is not affected by data transition density, requires no direct current (DC) response of the transmission link, and suffers from minimal ambiguity in resolution of the digital data.

  3. High energy, low frequency, ultrasonic transducer

    DOEpatents

    Brown, Albert E. (Hayward, CA)

    2000-01-01

    A wide bandwidth, ultrasonic transducer to generate nondispersive, extensional, pulsed acoustic pressure waves into concrete reinforced rods and tendons. The wave propagation distance is limited to double the length of the rod. The transducer acoustic impedance is matched to the rod impedance for maximum transfer of acoustic energy. The efficiency of the transducer is approximately 60 percent, depending upon the type of active elements used in the transducer. The transducer input energy is, for example, approximately 1 mJ. Ultrasonic reflections will occur at points along the rod where there are changes of one percent of a wavelength in the rod diameter. A reduction in the rod diameter will reflect a phase reversed echo, as compared with the reflection from an incremental increase in diameter. Echo signal processing of the stored waveform permits a reconstruction of those echoes into an image of the rod. The ultrasonic transducer has use in the acoustic inspection of long (40+foot) architectural reinforcements and structural supporting members, such as in bridges and dams.

  4. Ultrasonic measurement of larynx height and vocal fold vibratory pattern.

    PubMed

    Hamlet, S L

    1980-07-01

    This paper describes the modification and extension of an ultrasonic through-transmission technique for examining vocal fold activity. The purpose was to achieve improved lateral resolution in the cranio-caudal dimension. A transducer was specially designed to produce an eliptical beam, so that a measurable signal might be received through the extreme upper and lower edges of the vibrating vocal folds. An interpretation of amplitude variation within the ultrasonic waveform is offered, with illustrative data shown for a single subject. PMID:7391354

  5. Ultrasonic determination of chicken composition.

    PubMed

    Chanamai, R; McClements, D J

    1999-11-01

    An ultrasonic technique has been developed for measuring the composition of chicken meat. The relationship between the composition and ultrasonic velocity of chicken meat was determined using chicken analogues of different composition, prepared from dried chicken powder, corn oil, and distilled water. The ultrasonic velocity of chicken analogues was measured at temperatures from 5 to 35 degrees C using an ultrasonic spectrometer. The ultrasonic velocity increased with solids-nonfat (SNF) content at all temperatures but had a more complex dependence on fat content. Around 15 degrees C the ultrasonic velocity was independent of fat content; however, at lower temperatures it increased with fat content, and at higher temperatures it decreased. Semiempirical equations were developed to describe the relationship between ultrasonic velocity and chicken composition. To determine the usefulness of these equations, the ultrasonic velocities of various chicken meats were measured. The compositions of the chicken meats predicted on the basis of ultrasonic measurements were in good agreement with those determined by using standard methods (r(2) > 0. 97). The ultrasonic technique could also be used to measure the solid fat content of chicken fat. This study shows that ultrasonic velocity measurements can be used to characterize chicken composition. This method has great potential for application in the food industry because it is simple, fast, nondestructive, and reliable. PMID:10552873

  6. Plate Wave Resonance with Air-Coupled Ultrasonics

    NASA Astrophysics Data System (ADS)

    Bar, H. N.; Dayal, V.; Barnard, D.; Hsu, D. K.

    2010-02-01

    Air-coupled ultrasonic transducers can excite plate waves in metals and composites. The coincidence effect, i.e., the wave vector of plate wave coincides with projection of exciting airborne sound vector, leads to a resonance which strongly amplifies the sound transmission through the plate. The resonance depends on the angle of incidence and the frequency. In the present study, the incidence angle for maximum transmission (?max) is measured in plates of steel, aluminum, carbon fiber reinforced composites and honeycomb sandwich panels. The variations of (?max) with plate thickness are compared with theoretical values in steel, aluminum and quasi-isotropic carbon fiber composites. The enhanced transmission of air-coupled ultrasound at oblique incidence can substantially improve the probability of flaw detection in plates and especially in honeycomb structures. Experimental air-coupled ultrasonic scan of subtle flaws in CFRP laminates showed definite improvement of signal-to-noise ratio with oblique incidence at ?max.

  7. Effect of External Magnetic Field on Ultrasonic Propagation Velocity in Magnetic Fluids

    NASA Astrophysics Data System (ADS)

    Motozawa, Masaaki; Matsumoto, Yoshiyuki; Sawada, Tatsuo

    Experimental results for the properties of ultrasonic propagation velocity in kerosene-based and water-based magnetic fluids are reported. Ultrasonic wave frequencies of 1MHz, 2MHz and 4MHz are used and the measurement scheme is based on the pulse method. The external magnetic field intensity is varied from 0mT to 550mT and the angle between the magnetic field direction and the direction of ultrasonic wave propagation is varied from 0° to 90°. The ultrasonic propagation velocity in magnetic fluids is dependent on temperature, elapsed time of applying the magnetic field, and magnetic field intensity. Hysteresis and anisotropy of ultrasonic propagation velocity are observed. These interesting results seem to be related to chain-like cluster formation in the magnetic fluids and the characteristic period of Brownian motion of the magnetic particles.

  8. Ultrasonic Flow Measurement at High, Cryo or Ordinary Temperatures Using Wetted and Clamp-On Transducers by

    Microsoft Academic Search

    Martin Bragg; Rory McMahon; Per Fredrickson; Larry Lynnworth

    1999-01-01

    This paper explains the problems in measuring flow by the ultrasonic transmission method at high temperature, and offers solutions based on waveguide buffers. Buffer waveguides only a foot or so in length (~300 mm) convectively cool down enough at their \\

  9. Simulation of transducer-couplant effects on broadband ultrasonic signals

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1980-01-01

    The increasing use of broadband, pulse-echo ultrasonics in nondestructive evaluation of flaws and material properties has generated a need for improved understanding of the way signals are modified by coupled and bonded thin-layer interfaces associated with transducers. This understanding is most important when using frequency spectrum analyses for characterizing material properties. In this type of application, signals emanating from material specimens can be strongly influenced by couplant and bond-layers in the acoustic path. Computer synthesized waveforms were used to simulate a range of interface conditions encountered in ultrasonic transducer systems operating in the 20 to 80 MHz regime. The adverse effects of thin-layer multiple reflections associated with various acoustic impedance conditions are demonstrated. The information presented is relevant to ultrasonic transducer design, specimen preparation, and couplant selection.

  10. Ultrasonic sensing of GMAW: Laser/EMAT defect detection system

    SciTech Connect

    Carlson, N.M.; Johnson, J.A.; Larsen, E.D. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Van Clark, A. Jr.; Schaps, S.R.; Fortunko, C.M. [National Inst. of Standards and Technology, Boulder, CO (United States)

    1992-08-01

    In-process ultrasonic sensing of welding allows detection of weld defects in real time. A noncontacting ultrasonic system is being developed to operate in a production environment. The principal components are a pulsed laser for ultrasound generation and an electromagnetic acoustic transducer (EMAT) for ultrasound reception. A PC-based data acquisition system determines the quality of the weld on a pass-by-pass basis. The laser/EMAT system interrogates the area in the weld volume where defects are most likely to occur. This area of interest is identified by computer calculations on a pass-by-pass basis using weld planning information provided by the off-line programmer. The absence of a signal above the threshold level in the computer-calculated time interval indicates a disruption of the sound path by a defect. The ultrasonic sensor system then provides an input signal to the weld controller about the defect condition. 8 refs.

  11. Ultrasonic Drilling and Coring

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph

    1998-01-01

    A novel drilling and coring device, driven by a combination, of sonic and ultrasonic vibration, was developed. The device is applicable to soft and hard objects using low axial load and potentially operational under extreme conditions. The device has numerous potential planetary applications. Significant potential for commercialization in construction, demining, drilling and medical technologies.

  12. Scanning ultrasonic probe

    DOEpatents

    Kupperman, D.S.; Reimann, K.J.

    1980-12-09

    The invention is an ultrasonic testing device for rapid and complete examination of the test specimen, and is particularly well suited for evaluation of tubular test geometries. A variety of defect categories may be detected and anlayzed at one time and their positions accurately located in a single pass down the test specimen.

  13. Ultrasonic agitation in microchannels

    Microsoft Academic Search

    Martin Bengtsson; Thomas Laurell

    2004-01-01

    This paper describes an acoustic method for inducing rotating vortex flows in microchannels. An ultrasonic crystal is used to create an acoustic standing wave field in the channel and thus induce a Rayleigh flow transverse to the laminar flow in the channel. Mixing in microchannels is strictly diffusion-limited because of the laminar flow, a transverse flow will greatly enhance mixing

  14. Design and experimental results of a tunable vibration turning device operating at ultrasonic frequencies

    Microsoft Academic Search

    Jerald L. Overcash; James F. Cuttino

    2009-01-01

    The development of a tunable ultrasonic vibration-assisted diamond-turning tool is described. The resonance operation method, which formerly served to achieve mechanical motion at ultrasonic frequencies, is now replaced by a newly developed pulse driving technique. The prototype tools allow for vibration frequencies from dc up to 40kHz and vibration amplitudes from 0 to 10?m. This paper reviews the design of

  15. Pulse Shaping, Modulation and Spectrum Shaping for UWB Wireless Communications and the Effects on Interference for Single and Multiband Transmission of UWB Signals

    Microsoft Academic Search

    Michael Sablatash

    2006-01-01

    This paper focuses on pulse shaping, modulation techniques, randomization by pseudo noise (PN) and other sequences, and power spectral density (PSD) shaping of ultra wideband (UWB) wireless communication signals and their effects on interference into and by other communication signals. The evolution of techniques proposed for these, and implementations based on research and development since the early 1990's, to those

  16. PSIDD: A Post-Scan Interactive Data Display system for ultrasonic scans

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Szatmary, Steven A.

    1993-01-01

    An ultrasonic data display system was developed at NASA Lewis Research Center that allows the user to interactively examine digitized waveforms and processed information associated with any specific scan location of an ultrasonic contact scan. This information is displayed on a video display monitor and includes acquired time-domain waveforms, frequency-domain magnitude and phase spectra, and ultrasonic properties (pulse velocity, phase velocity, reflection coefficient, attenuation coefficient, attenuation coefficient error) as a function of frequency for a material. This report describes the system features and illustrates the system's usefulness for nondestructive materials characterization.

  17. A New Approach to Ultrasonic Tissue Characterization on Second Harmonic Component of 100 MHz

    NASA Astrophysics Data System (ADS)

    Nishimura, Toshihiro; Kubota, Akira; Yoshihara, Sozaboru; Kanda, Hiroshi; Senda, Syoichi; Saito, Masao

    In order to evaluate the properties of ultrasonic nonlinear scattering, the ultrasonic attenuation characteristics using the second harmonic component of the transmitted ultrasonic signal through normal and fatty hen liver as well as the fundamental component were measured. In The experiment, a 50MHz transducer was by reflection method and its frequency dependency was analyzed. The second harmonic component was detected by using pulse inversion detection technique. The experimental results showed that the attenuation coefficient was almost constant around second harmonic frequency dependence can identify the property of normal and fatty hen liver.

  18. High-temperature ultrasonic sensor for in-situ monitoring of hot isostatic processing

    NASA Astrophysics Data System (ADS)

    Stubbs, David A.; Dutton, Rollie E.

    1996-11-01

    A sensor has been developed and tested that is capable of emitting and receiving ultrasonic energy at temperatures exceeding 900 degrees C and pressures above 150 MPa. The sensor is based on a unique form of aluminum nitride that retains tits piezoelectric properties at high temperatures. The sensor works with standard ultrasonic pulse-receivers and has demonstrated the capability of measuring workpiece deformation during hot isostatic pressing (HIP). Details of the sensor design, performance, and coupling of the ultrasound to the workpiece are described. Ultrasonic data acquired by the sensor, in situ, during HIP runs and at elevated temperatures in air are presented.

  19. Ultrasonic wave velocity measurement in small polymeric and cortical bone specimens

    NASA Technical Reports Server (NTRS)

    Kohles, S. S.; Bowers, J. R.; Vailas, A. C.; Vanderby, R. Jr

    1997-01-01

    A system was refined for the determination of the bulk ultrasonic wave propagation velocity in small cortical bone specimens. Longitudinal and shear wave propagations were measured using ceramic, piezoelectric 20 and 5 MHz transducers, respectively. Results of the pulse transmission technique were refined via the measurement of the system delay time. The precision and accuracy of the system were quantified using small specimens of polyoxymethylene, polystyrene-butadiene, and high-density polyethylene. These polymeric materials had known acoustic properties, similarity of propagation velocities to cortical bone, and minimal sample inhomogeneity. Dependence of longitudinal and transverse specimen dimensions upon propagation times was quantified. To confirm the consistency of longitudinal wave propagation in small cortical bone specimens (< 1.0 mm), cut-down specimens were prepared from a normal rat femur. Finally, cortical samples were prepared from each of ten normal rat femora, and Young's moduli (Eii), shear moduli (Gij), and Poisson ratios (Vij) were measured. For all specimens (bone, polyoxymethylene, polystyrene-butadiene, and high-density polyethylene), strong linear correlations (R2 > 0.997) were maintained between propagation time and distance throughout the size ranges down to less than 0.4 mm. Results for polyoxymethylene, polystyrene-butadiene, and high-density polyethylene were accurate to within 5 percent of reported literature values. Measurement repeatability (precision) improved with an increase in the wave transmission distance (propagating dimension). No statistically significant effect due to the transverse dimension was detected.

  20. Ultrasonic texture characterization of aluminum, zirconium and titanium alloys

    SciTech Connect

    Anderson, A.J.

    1997-10-08

    This work attempts to show the feasibility of nondestructive characterization of non-ferrous alloys. Aluminum alloys have a small single crystal anisotropy which requires very precise ultrasonic velocity measurements for derivation of orientation distribution coefficients (ODCs); the precision in the ultrasonic velocity measurement required for aluminum alloys is much greater than is necessary for iron alloys or other alloys with a large single crystal anisotropy. To provide greater precision, some signal processing corrections need to be applied to account for the inherent, half-bandwidth offset in triggered pulses when using a zero-crossing technique for determining ultrasonic velocity. In addition, alloys with small single crystal anisotropy show a larger dependence on the single crystal elastic constants (SCECs) when predicting ODCs which require absolute velocity measurements. Attempts were made to independently determine these elastics constants in an effort to improve correlation between ultrasonically derived ODCs and diffraction derived ODCs. The greater precision required to accurately derive ODCs in aluminum alloys using ultrasonic nondestructive techniques is easily attainable. Ultrasonically derived ODCs show good correlation with derivations made by Bragg diffraction techniques, both neutron and X-ray. The best correlation was shown when relative velocity measurements could be used in the derivations of the ODCs. Calculation of ODCs in materials with hexagonal crystallites can also be done. Because of the crystallite symmetries, more information can be extracted using ultrasonic techniques, but at a cost of requiring more physical measurements. Some industries which use materials with hexagonal crystallites, e.g. zirconium alloys and titanium, have traditionally used texture parameters which provide some specialized measure of the texture. These texture parameters, called Kearns factors, can be directly related to ODCs.

  1. Comparison of ultrasonic image features with echodynamic curves for defect classification and characterization

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Wedge, Sam; Rogerson, Allan; Drinkwater, Bruce

    2015-03-01

    Ultrasonic array imaging and multi-probe pulse echo inspection are two common ultrasonic techniques used for defect detection, classification and characterization in non-destructive evaluation. Compared to multi-probe pulse echo inspection, ultrasonic array imaging offers some advantages such as higher resolution images and the requirement to obtain fewer measurements. However, it is also limited by a lack of industry-approved inspection procedures and standards. In this paper, several artificial planar and volumetric weld defects of different orientations and locations embedded in 60 mm thick welded ferritic test specimens were measured using both ultrasonic arrays and multiple single crystal probes. The resultant TFM images and echodynamic curves for each defect were compared and the results demonstrate the correlations between TFM image features and echodynamic curve characteristics. Combining the analysis of multi-probe pulse echo inspection data and ultrasonic array images offers better classification and characterization of defects. These findings benefit the further development of industrial ultrasonic array inspection procedures and encourage the uptake of TFM technology within industry.

  2. A correlation of air-coupled ultrasonic and thermal diffusivity data for CFCC materials

    SciTech Connect

    Pillai, T.A.K. [Univ. of Wisconsin, LaCrosse, WI (United States). Dept. of Physics; Easler, T.E.; Szweda, A. [Dow Corning Corp., Midland, MI (United States). Advanced Ceramics Program] [and others

    1997-01-01

    An air-coupled (non contact) through-transmission ultrasonic investigation has been conducted on 2D multiple ply Nicalon{trademark} SiC fiber/SiNC CFCC panels as a function of number of processing cycles. Corresponding thermal diffusivity imaging was also conducted. The results of the air-coupled ultrasonic investigation correlated with thermal property variations determined via infrared methods. Areas of delaminations were detected and effects of processing cycles were also detected.

  3. Surface nanocrystallization of 316L stainless steel induced by ultrasonic shot peening

    Microsoft Academic Search

    G. Liu; J. Lu; K. Lu

    2000-01-01

    A new technique was introduced to realize surface nanocrystallization (i.e. generation of a surface layer of nanostructures) on a 316L stainless steel by means of ultrasonic shot peening treatment. The microstructural evolution of the 316L stainless steel was characterized by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. After the ultrasonic shot peening treatment, obvious grain refinement was

  4. Center crack detection during continuous casting of aluminum by laser ultrasonic measurements

    NASA Astrophysics Data System (ADS)

    Grün, Hubert; Mitter, Thomas; Roither, Jürgen; Betz, Andreas; Bozorgi, Salar; Burgholzer, Peter

    2014-05-01

    Crack detection during continuous direct chill casting of aluminum is a matter of economics. Determining cracks during production process saves money, energy and raw material. Of course, a non-destructive method is required for this evaluation. Because of temperature concerns conventional ultrasound is not applicable. One non-contact alternative is laser ultrasonics. In laser ultrasonics short laser pulses illuminate the sample. The electromagnetic energy gets absorbed at the surface of the sample and results in local heating followed by expansion. Thereby broadband ultrasonic waves are launched which propagate through the sample and get back reflected or scattered at interfaces (cracks, blowholes,…) like conventional ultrasonic waves. Therefore laser ultrasonics is an alternative thermal infrared technology. By using an interferometer also the detection of the ultrasonic waves at the sample surface is done in a remote manner. During preliminary examinations in the lab by scanning different aluminum studs it was able to distinguish between studs with and without cracks. The prediction of the dimension of the crack by evaluation of the damping of the broadband ultrasonic waves was possible. With simple image reconstruction methods one can localize the crack and give an estimation of its extent and even its shape. Subsequent first measurements using this laser ultrasonic setup during the continuous casting of aluminum were carried out and showed the proof of principle in an industrial environment with elevated temperatures, dust, cooling water and vibrations.

  5. 21 CFR 890.5300 - Ultrasonic diathermy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5300 Ultrasonic diathermy. (a) Ultrasonic diathermy for...

  6. 21 CFR 890.5300 - Ultrasonic diathermy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5300 Ultrasonic diathermy. (a) Ultrasonic diathermy for...

  7. 21 CFR 890.5300 - Ultrasonic diathermy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5300 Ultrasonic diathermy. (a) Ultrasonic diathermy for...

  8. Comparison of pulsed field gel electrophoresis and repetitive sequence polymerase chain reaction as genotyping methods for detection of genetic diversity and inferring transmission of Salmonella

    Microsoft Academic Search

    Ronald M. Weigel; Baozhen Qiao; Belete Teferedegne; Dong Kyun Suh; David A. Barber; Richard E. Isaacson; Bryan A. White

    2004-01-01

    Pulsed field gel electrophoresis (PFGE) using restriction enzymes AvrII, SpeI, and XbaI, and repetitive sequence polymerase chain reaction (Rep-PCR) using BOX, ERIC, and REP primers, were compared with respect to their ability to detect genetic differences among 68 Salmonella isolates from nine Illinois swine farms. Both genotyping methods had high reproducibility of fragment numbers (reliability>0.9) and sizes (reliability>0.85), and produced

  9. Ultrasonic Doppler measurement of renal artery blood flow

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Implantable pulsed Doppler ultrasonic flowmeter development has resulted in designs for application to the aortas of dogs and humans, and to human renal and coronary arteries. A figure of merit was derived for each design, indicating the degree of its precision. An H-array design for transcutaneous observation of blood flow was developed and tested in vitro. Two other simplified designs for the same purpose obviate the need to determine vessel orientation. One of these will be developed in the next time period. Techniques for intraoperative use and for implantation have had mixed success. While satisfactory on large vessels, higher ultrasonic frequencies and alteration of transducer design are required for satisfactory operation of pulsed Doppler flowmeters with small vessels.

  10. Ultrasonic Transducers for Fourier Analysis.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1995-01-01

    Describes an experiment that uses the ultrasonic transducer for demonstrating the Fourier components of waveshapes such as the square and triangular waves produced by laboratory function generators. (JRH)

  11. Ultrasonic leak detector

    SciTech Connect

    Fisch, A.C.

    1989-03-07

    This patent describes an ultrasonic leak test apparatus comprising means for sequentially feeding a plurality of workpieces to a test station, means for alternately lifting workpieces in sequence from the transfer means to an elevated position and lowering workpieces onto the transfer means in a lowered position, means for forming a sound chamber enclosing a workpiece on the elevator means, and means for selectively feeding air under pressure into a workpiece enclosed in the chamber, and means for ultrasonically detecting air leakage from within the workpiece. The sequentially-feeding means comprises a transfer line including support means defining a transfer plane, transfer means positioned on opposed sides of the support means for selectively engaging and disengaging workpieces on the support means, and indexing means coupled to the transfer means for selectively indexing the transfer means for moving workpieces sequentially along the support means onto the elevator means.

  12. A Method For The Verification Of Wire Crimp Compression Using Ultrasonic Inspection

    NASA Technical Reports Server (NTRS)

    Cramer, K. E.; Perey, Daniel F.; Yost, William t.

    2010-01-01

    The development of a new ultrasonic measurement technique to assess quantitatively wire crimp terminations is discussed. The amplitude change of a compressional ultrasonic wave propagating at right angles to the wire axis and through the junction of a crimp termination is shown to correlate with the results of a destructive pull test, which is a standard for assessing crimp wire junction quality. To demonstrate the technique, the case of incomplete compression of crimped connections is ultrasonically tested, and the results are correlated with pull tests. Results show that the nondestructive ultrasonic measurement technique consistently predicts good crimps when the ultrasonic transmission is above a certain threshold amplitude level. A quantitative measure of the quality of the crimped connection based on the ultrasonic energy transmitted is shown to respond accurately to crimp quality. A wave propagation model, solved by finite element analysis, describes the compressional ultrasonic wave propagation through the junction during the crimping process. This model is in agreement within 6% of the ultrasonic measurements. A prototype instrument for applying this technique while wire crimps are installed is also presented. The instrument is based on a two-jaw type crimp tool suitable for butt-splice type connections. A comparison of the results of two different instruments is presented and shows reproducibility between instruments within a 95% confidence bound.

  13. Borehole data transmission apparatus

    DOEpatents

    Kotlyar, O.M.

    1993-03-23

    A borehole data transmission apparatus is described whereby a centrifugal pump impeller(s) is used to provide a turbine stage having substantial pressure characteristics in response to changing rotational speed of a shaft for the pressure pulsing of data from the borehole through the drilling mud to the surface of the earth.

  14. Ultrasonic Cutting of Foods

    Microsoft Academic Search

    Yvonne Schneider; Susann Zahn; Harald Rohm

    2011-01-01

    \\u000a In the field of food engineering, cutting is usually classified as a mechanical unit operation dealing with size reduction\\u000a by applying external forces on a bulk product. Ultrasonic cutting is realized by superpositioning the macroscopic feed motion\\u000a of the cutting device or of the product with a microscopic vibration of the cutting tool. The excited tool interacts with\\u000a the product

  15. Miniature implantable ultrasonic echosonometer

    NASA Technical Reports Server (NTRS)

    Kojima, G. K. (inventor)

    1978-01-01

    A miniature echosonometer adapted for implantation in the interior of an animal for imaging the internal structure of a organ, tissue or vessel is presented. The echosonometer includes a receiver/transmitter circuit which is coupled to an ultrasonic transducer. Power is coupled to the echosonometer by electromagnetic induction through the animal's skin. Imaging signals from the echosonometer are electromagnetically transmitted through the animal's skin to an external readout apparatus.

  16. Piezocomposites improve ultrasonic testing

    SciTech Connect

    Meyer, P.A. [Krautkramer Branson, Lewistown, PA (United States)

    1997-02-01

    Ultrasonic testing is a nondestructive technique in which beams of high-frequency sound waves are introduced into materials for the detection of surface and subsurface flaws. Ultrasound probes--the devices that generate and receive acoustic energy--have historically been made of lead zirconate titanate (PZT) and similar piezoelectric ceramics. these materials have the capability to convert an electrical signal into acoustic energy (sound waves) to be transmitted into a part. The piezoelectric ceramic then converts the returning echoes into an electrical signal, which is evaluated by an electronic instrument similar to an oscilloscope. Although conventional transducers based on piezoelectric ceramics provide adequate performance, newly undeveloped piezocomposite transducers enable ultrasonic nondestructive testing devices to detect flaws with greater sensitivity than possible before. These are mixtures of conventional piezoelectric ceramics and polymers such as epoxy, polyurethane, and silicone rubber. A typical piezocomposite consists of an array of ceramic rods in a polymer matrix. This article explains the basics of ultrasonic testing, describes the advantages of the composite detector material, and shows how it is applied to detect flaws.

  17. Design of pulse transformers for PFL charging

    Microsoft Academic Search

    G. J. Rohwein

    1979-01-01

    Air core pulse transformers powered by low voltage capacitor banks can be simple efficient systems for charging high-voltage (0.5 to 3 MV), pulse forming transmission lines (PFL) such as those used in electron and ion beam accelerators. In these applications pulse transformers must have the combined capability of high voltage endurance and high energy transfer efficiency, particularly in repetitive pulse

  18. Ultrasonic evaluation of matrix damage in impacted composite laminates

    Microsoft Academic Search

    F Aymerich; S Meili

    2000-01-01

    Conventional ultrasonic inspection methods are largely used for detection of delaminations in composite materials while only recently new techniques have been proposed to identify matrix cracks in simple tension loaded coupon specimens. In this study delaminations and matrix cracking caused by low-energy impacts on quasi-isotropic carbon\\/PEEK laminated plates are examined by means of different pulse-echo techniques: conventional time-of-flight and amplitude

  19. Aluminum buffer rods for ultrasonic monitoring at elevated temperatures

    Microsoft Academic Search

    Yuu Ono; Cheng-Kuei Jen; Chun-Yi Su

    2005-01-01

    Aluminum (Al) buffer rods, having circular, square, and rectangular cross-section shapes with and without cladding, were experimentally investigated to achieve high performance in ultrasound for industrial process monitoring. Focus was devoted to the signal-to noise ratio (SNR) aspect in pulse-echo mode because high SNR can make many practical ultrasonic monitoring applications feasible. If the size of the rod cross section

  20. Elastic moduli of boron carbide/copper composites from -40/sup 0/C to 800/sup 0/C by ultrasonic methods

    SciTech Connect

    Gieske, J.H.

    1980-10-01

    An ultrasonic through-transmission technique for high attenuating materials was developed to determine the ultrasonic longitudinal and shear velocities in B/sub 4/C/Cu composites to 800/sup 0/C. Ultrasonic velocity data was used to calculate Young's modulus, shear modulus, and Poisson's ratio for the composites from -40/sup 0/C to 800/sup 0/C. 5 figures, 1 table.

  1. 30 ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 45, no. 1, january 1998 Channel Defect Detection in Food Packages

    E-print Network

    Illinois at Urbana-Champaign, University of

    - generated channels which simulate defects in food pack- ages using pulse-echo ultrasonic imaging techniques30 ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 45, no. 1, january-generated channels that simulate de- fects with diameters between 9 and 325 m in the seal plane traversing the major

  2. Ultrasonic Imaging of Welded Metals Using Simplified Ultrasonic Computerized Tomography

    Microsoft Academic Search

    Kyung-Cho Kim; Hiroaki Fukuhara; Hisashi Yamawaki

    2002-01-01

    In this paper, as a new measurement method to estimate the infinitesimal change of material condition, the simplified ultrasonic computerized tomography (CT) system, which uses the information of three directions, i.e., the 90°, +45\\\\circ and -45\\\\circ directions about the inspection plane, is proposed. The use of the simplified ultrasonic CT system has two merits: First, the measurement time is very

  3. Shielding of Piezoelectric Ultrasonic Probes in Hall Effect Imaging

    PubMed Central

    Wen, Han; Bennett, Eric; Wiesler, David G.

    2010-01-01

    This paper addresses significant sources of electromagnetic noise in Hall effect imaging. Hall effect imaging employs large electrical pulses for signal generation and high sensitivity ultrasonic probes for signal reception. Coherent noise arises through various coupling mechanisms between the excitation pulse and the probe. In this paper, the coupling mechanisms are experimentally isolated and theoretically analyzed. Several methods of shielding the probe from electromagnetic interference are devised and tested. These methods are able to reduce the noise to levels below the random thermal noise, thereby improving the signal-to-noise ratio in HEI by two orders of magnitude. PMID:9921620

  4. Extraction of activated sludge bacteria exopolymers by ultrasonication

    Microsoft Academic Search

    V. R. F. Matias; M. C. Cammarota; G. L. Sant'Anna

    2003-01-01

    Ultrasonication for the extraction of activated sludge exopolymers was evaluated by total cell count, exopolymer extraction and transmission electron microscopy (TEM). A high deflocculation was achieved after 30 s of sonication in PBS (phosphate-buffered saline). TEM showed that cell lysis was minimal only when sludges were sonicated for 30 s. For sludges sonicated for 30, 90 and 420 s and stained with Ruthenium

  5. Correcting for Strong Eddy Current Induced B0 Modulation Enables Two-Spoke RF Pulse Design with Parallel Transmission: Demonstration at 9.4T in the Human Brain

    PubMed Central

    Wu, Xiaoping; Adriany, Gregor; Ugurbil, Kamil; Van de Moortele, Pierre-Francois

    2013-01-01

    Successful implementation of homogeneous slice-selective RF excitation in the human brain at 9.4T using 16-channel parallel transmission (pTX) is demonstrated. A novel three-step pulse design method incorporating fast real-time measurement of eddy current induced B0 variations as well as correction of resulting phase errors during excitation is described. To demonstrate the utility of the proposed method, phantom and in-vivo experiments targeting a uniform excitation in an axial slice were conducted using two-spoke pTX pulses. Even with the pre-emphasis activated, eddy current induced B0 variations with peak-to-peak values greater than 4 kHz were observed on our system during the rapid switches of slice selective gradients. This large B0 variation, when not corrected, resulted in drastically degraded excitation fidelity with the coefficient of variation (CV) of the flip angle calculated for the region of interest being large (?12% in the phantom and ?35% in the brain). By comparison, excitation fidelity was effectively restored, and satisfactory flip angle uniformity was achieved when using the proposed method, with the CV value reduced to ?3% in the phantom and ?8% in the brain. Additionally, experimental results were in good agreement with the numerical predictions obtained from Bloch simulations. Slice-selective flip angle homogenization in the human brain at 9.4T using 16-channel 3D spoke pTX pulses is achievable despite of large eddy current induced excitation phase errors; correcting for the latter was critical in this success. PMID:24205098

  6. Correcting for strong eddy current induced B0 modulation enables two-spoke RF pulse design with parallel transmission: demonstration at 9.4T in the human brain.

    PubMed

    Wu, Xiaoping; Adriany, Gregor; Ugurbil, Kamil; Van de Moortele, Pierre-Francois

    2013-01-01

    Successful implementation of homogeneous slice-selective RF excitation in the human brain at 9.4T using 16-channel parallel transmission (pTX) is demonstrated. A novel three-step pulse design method incorporating fast real-time measurement of eddy current induced B0 variations as well as correction of resulting phase errors during excitation is described. To demonstrate the utility of the proposed method, phantom and in-vivo experiments targeting a uniform excitation in an axial slice were conducted using two-spoke pTX pulses. Even with the pre-emphasis activated, eddy current induced B0 variations with peak-to-peak values greater than 4 kHz were observed on our system during the rapid switches of slice selective gradients. This large B0 variation, when not corrected, resulted in drastically degraded excitation fidelity with the coefficient of variation (CV) of the flip angle calculated for the region of interest being large (~ 12% in the phantom and ~ 35% in the brain). By comparison, excitation fidelity was effectively restored, and satisfactory flip angle uniformity was achieved when using the proposed method, with the CV value reduced to ~ 3% in the phantom and ~ 8% in the brain. Additionally, experimental results were in good agreement with the numerical predictions obtained from Bloch simulations. Slice-selective flip angle homogenization in the human brain at 9.4T using 16-channel 3D spoke pTX pulses is achievable despite of large eddy current induced excitation phase errors; correcting for the latter was critical in this success. PMID:24205098

  7. Self-starting and overclocking a harmonically mode-locking WRC-FPLD with a dual-loop feedback controller for 10 Gb s?1 pulse-data transmission

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Ju; Chi, Yu-Chieh; Lin, Gong-Ru

    2013-06-01

    The self-starting and overclocking of a harmonically mode-locked weak-resonant-cavity Fabry–Perot laser diode (WRC-FPLD) with a dual-loop coupled optoelectronic oscillator (COEO) based feedback controller is demonstrated to perform a clock-free pulsed data transmission at 10 Gb s?1. The WRC-FPLD is considered as the preferred candidate for harmonic mode-locking due to its highly asymmetric cavity architecture, whereby the spontaneous noise can be significantly suppressed without inducing large intra-cavity loss. With the dual-loop COEO configuration, the WRC-FPLD can be boosted to four times of its original modulation bandwidth such that the pulsed carrier quality can be refined. The structure-optimizing principle with the closed-loop model is corroborated by the effective spurious-noise-suppression. The lowest phase noises as low as ?100 dBc Hz?1 at 10 kHz with corresponding RMS timing jitter of 0.67 ps are measured. This is achieved by individually inserting 100 and 120 m long single mode fiber segments into two decoupled arms, the dual-loop COEO before the optical receiver pair. The BER performance reaches a minimum with the optimized SMF segment lengths. However, the spurious peaks arise to degrade the BER performance as the phase noise and jitter are inevitably enlarged when inserting longer SMF segments. After modulating the optimized output pulse train with the pseudo-random-bit-sequence data triggered by the same COEO clock, the SNR can achieve 10.9 dB and the receiving sensitivity is ?19.2 dBm.

  8. Ultrasonic Attenuation in Lanthanum Monochalcogenides

    Microsoft Academic Search

    Raja Ram Yadav; Devraj Singh

    2001-01-01

    Ultrasonic attenuation due to phonon-phonon interaction and thermoelastic relaxation are studied in Lanthanum Monochalcogenides in direction at different higher temperatures. For evaluation of ultrasonic absorption coefficients the second and third order elastic constants (SOEC) and (TOEC) are also calculated. Shear wave attenuation shows maximum along propagation direction with polarized along and the attenuation increases at higher temperatures. Thermo-elastic loss is

  9. Nonlinear Response of the High-Temperature Superconductor YBa2Cu3O7-? to the Transmission of Intense Terahertz Pulses

    NASA Astrophysics Data System (ADS)

    Kawayama, Iwao; Glossner, Andreas; Zhang, Caihong; Kikuta, Shinya; Murakami, Hironaru; Müller, Paul; Tonouchi, Masayoshi

    2012-02-01

    High-Power Terahertz Time-Domain Spectroscopy (THz-TDS) was used to examine YBa2Cu3O7-? thin films when transmitted by intense single-cycle THz pulses. This allowed for an investigation of the nonlinear, time-resolved behavior of YBa2Cu3O7-? in the presence of strong THz electric fields for the first time. High field strengths of tens of kV cm-1 were achieved by improving the efficiency of optical rectification in LiNbO3 through the tilted-pulse-front method and by ensuring a tight focusing of the THz beam. In the case of low field strengths, the behavior of the thin films agrees with previous examinations of YBa2Cu3O7-? by means of conventional, low-power THz-TDS. However, for strong THz electric fields, it was found by analysis with the two-fluid model that the superfluid population decreases dramatically, possibly due to Cooper pair breakup. This was accompanied by a drop in the imaginary part of the conductivity in the investigated frequency range of 0.2 to 0.8 THz. The results further suggest a decrease of the effective mass of the carriers for strong THz fields.

  10. Enzyme-catalyzed synthesis and kinetics of ultrasonic-assisted biodiesel production from waste tallow.

    PubMed

    Adewale, Peter; Dumont, Marie-Josée; Ngadi, Michael

    2015-11-01

    The use of ultrasonic processing was evaluated for its ability to achieve adequate mixing while providing sufficient activation energy for the enzymatic transesterification of waste tallow. The effects of ultrasonic parameters (amplitude, cycle and pulse) and major reaction factors (molar ratio and enzyme concentration) on the reaction kinetics of biodiesel generation from waste tallow bio-catalyzed by immobilized lipase [Candida antarctica lipase B (CALB)] were investigated. Three sets of experiments namely A, B, and C were conducted. In experiment set A, two factors (ultrasonic amplitude and cycle) were investigated at three levels; in experiment set B, two factors (molar ratio and enzyme concentration) were examined at three levels; and in experiment set C, two factors (ultrasonic amplitude and reaction time) were investigated at five levels. A Ping Pong Bi Bi kinetic model approach was employed to study the effect of ultrasonic amplitude on the enzymatic transesterification. Kinetic constants of transesterification reaction were determined at different ultrasonic amplitudes (30%, 35%, 40%, 45%, and 50%) and enzyme concentrations (4, 6, and 8wt.% of fat) at constant molar ratio (fat:methanol); 1:6, and ultrasonic cycle; 5Hz. Optimal conditions for ultrasound-assisted biodiesel production from waste tallow were fat:methanol molar ratio, 1:4; catalyst level 6% (w/w of fat); reaction time, 20min (30 times less than conventional batch processes); ultrasonic amplitude 40% at 5Hz. The kinetic model results revealed interesting features of ultrasound assisted enzyme-catalyzed transesterification (as compared to conventional system): at ultrasonic amplitude 40%, the reaction activities within the system seemed to be steady after 20min which means the reaction could proceed with or without ultrasonic mixing. Reversed phase high performance liquid chromatography indicated the biodiesel yield to be 85.6±0.08%. PMID:26186814

  11. Ultrasonic flow nozzle cleaning apparatus

    SciTech Connect

    Fridsma, D.E.; Silvestri, G.J. Jr.; Twerdochlib, M.

    1992-06-23

    This patent describes an ultrasonic cleaning apparatus for a venturi flow measuring nozzle mounted in a pipe of a steam power plant and having an inlet, venturi throat, and an outlet, the pipe and nozzle having fluid flowing therethrough, the cleaning occurring while the fluid is flowing. It comprises first ultrasonic transducer means mounted to connect to the inside of the pipe, disposed adjacent the inlet of the venturi flow nozzle and the means being in direct contact with the fluid flowing through the pipe for transmitting ultrasonic waves directly into and thereby exciting the fluid flowing through the venturi flow nozzle; and control means coupled to the first ultrasonic transducer means for activating the first ultrasonic transducer means.

  12. Determination of inlet transmission and conversion efficiencies for in situ measurements of the nocturnal nitrogen oxides, NO3, N2O5 and NO2, via pulsed cavity ring-down spectroscopy.

    PubMed

    Fuchs, Hendrik; Dubé, William P; Ciciora, Steven J; Brown, Steven S

    2008-08-01

    Pulsed cavity ring-down spectroscopy is a highly sensitive method for direct absorption spectroscopy that has been applied to in situ detection of NO3, N2O5 and NO2 in the atmosphere from a variety of platforms, including ships, aircraft, and towers. In this paper, we report the development of schemes to significantly improve the accuracy of these measurements. This includes the following: (1) an overall improvement in the inlet transmission efficiencies (92 +/- 2% for NO3 and 97 +/- 1% for N2O5) achieved primarily through a reduction in the inlet residence time; and (2) the development of a calibration procedure that allows regular determination of these efficiencies in the field by addition of NO3 or N2O5 to the inlet from a portable source followed by conversion of NO3 to NO2. In addition, the dependence of the instrument's sensitivity and accuracy to a variety of conditions encountered in the field, including variations in relative humidity, aerosol loading, and VOC levels, was systematically investigated. The rate of degradation of N2O5 transmission efficiency on the inlet and filter system due to the accumulation of inorganic aerosol was determined, such that the frequency of filter changes required for accurate measurements could be defined. In the absence of aerosol, the presence of varying levels of relative humidity and reactive VOC were found to be unimportant factors in the instrument's performance. The 1 sigma accuracy of the NO3, N2O5, and NO2 measured with this instrument are -9/+12, -8/+11, +/- 6%, respectively, where the -/+ signs indicate that the actual value is low/high relative to the measurement. The largest contribution to the overall uncertainty is now due to the NO3 absorption cross section rather than the inlet transmission efficiency. PMID:18588318

  13. Pulsed Electromagnet Emat for High Temperatures

    NASA Astrophysics Data System (ADS)

    Hernandez-Valle, F.; Dixon, S.

    2010-02-01

    We presented recently a design of Electromagnetic Acoustic Transducer (EMAT) that uses a pulsed electromagnet to provide the required magnetic field for operation. This new EMAT exhibited a significant improvement in the generated ultrasonic signal amplitude and signal to noise ratio, for operation on mild steel samples at room temperature, compared to equivalent EMATs that use permanent magnets. Results for using the pulsed electromagnet EMAT to generate and detect shear waves in mild steel at elevated temperatures are presented here.

  14. Transmission electron microscopy study of amorphous Ge2Sb2Te5 films induced by an ultraviolet single-pulse laser

    NASA Astrophysics Data System (ADS)

    Zhao, J. J.; Liu, F. R.; Han, X. X.; Zhu, Z.; Lin, X.; Liu, F.; Sun, N. X.

    2014-08-01

    Crystallization behaviors of ?-GST films with the thickness of 80 and 30 nm induced by an ultraviolet pulse laser were investigated by using TEM integrated with SAED. Firstly, crystalline phase morphologies were shown and analyzed. Both plate grains and spherical grains were found for 80 nm thick film, while only plate grains were found for 30 nm thick film. Then the relationship between the grain size and laser fluence for the 80 nm thick film was studied and the effects of film thickness on crystallization morphology were analyzed. Finally a crystallization process model based on the relationship of the crystallization starting temperature and heating temperature was constructed to elucidate how the solid-phase crystallization and melt-cooling crystallization occurred and developed. It also unified the crystallization starting temperature under static conditions and the crystallization starting temperature under laser inducing conditions.

  15. Ultrasonic aesthetic cranioplasty.

    PubMed

    Robiony, Massimo; Casadei, Matteo; Sbuelz, Massimo; Della Pietra, Lorenzo; Politi, Massimo

    2014-07-01

    The management of frontal bone injury is an important issue, and inappropriate management of such injuries may give rise to serious complications. Piezosurgery is a technique used to perform safe and effective osteotomies using piezoelectric ultrasonic vibrations. This instrument allows a safe method for osteotomy of the cranial vault in close proximity to extremely injury-sensitive tissue such as the brain. After a wide review of the literature, the authors present this technical report, introduce the use of piezosurgery to perform a safe "slim-osteotomies" for treatment of posttraumatic frontal bone deformities, and suggest the use of this instrument for aesthetic recontouring of the craniofacial skeleton. PMID:24914759

  16. Determination of Ultrasonic Parameters Based on Attenuation and Dispersion Measurements

    Microsoft Academic Search

    PING HE

    n , the traditional through- transmission method uses only the amplitude information of the recorded pulses to determine the two parameters, ? and n. In this paper, we propose a new method that utilizes both the amplitude and phase information of the pulses to determine the two parameters. According to this method, the two parame- ters are estimated by simultaneously

  17. Ultrasonic Mixing of Epoxy Curing Agents

    NASA Technical Reports Server (NTRS)

    Hodges, W. T.; St. Clair, T. L.

    1986-01-01

    New ultrasonic mixing technique used to mix several curing agents/epoxy combinations. Major component of commercially available base epoxy resin used in tetraglycidylmethylenedianiline (TGMDA). In ultrasonic mixing system cup holds resin and curing agent during acoustic excitation. Samples placed in cup with top to ultrasonic horn forming bottom of cup. Ultrasonically treated until amber colored and transparent. Because ultrasonic agitation drives out entrapped air, degassing not necessary before cure.

  18. Ultrasonic thermoacoustic cooler

    NASA Astrophysics Data System (ADS)

    Kwon, Young S.; El-Gendy, H.; Symko, O. G.

    2005-09-01

    The development of a thermoacoustic cooler in the ultrasonic range is presented. This cooler was designed to operate at a drive frequency of 24 kHz using air as the working fluid; the resonator is 7.1 mm long and it contains a cotton wool stack with copper heat exchangers at each end. Since the ultrasonic driver is a key element in this device, a major effort was made to optimize its performance and coupling to the resonator. It is a resonant piezoelectric monomorph loaded with a metallic cone for impedance matching to the resonator. By its design it is capable of intense sound levels, of order 140 dB and higher. The attained cooling power scales with the sound power levels and a COP larger than one is achieved. Studies of heat losses consist of PIV imaging of acoustic streaming (such as Eckart) in this device and back heat flow along the stack. The developed device shows much promise for rapid cooling of small samples. [Work supported by the Office of Naval Research.

  19. Ultrasonics and space instrumentation

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The design topic selected was an outgrowth of the experimental design work done in the Fluid Behavior in Space experiment, which relies on the measurement of minute changes of the pressure and temperature to obtain reasonably accurate volume determinations. An alternative method of volume determination is the use of ultrasonic imaging. An ultrasonic wave system is generated by wall mounted transducer arrays. The interior liquid configuration causes reflection and refraction of the pattern so that analysis of the received wave system provides a description of the configuration and hence volume. Both continuous and chirp probe beams were used in a laboratory experiment simulating a surface wetting propellant. The hardware included a simulated tank with gaseous voids, transmitting and receiving transducers, transmitters, receivers, computer interface, and computer. Analysis software was developed for image generation and interpretation of results. Space instrumentation was pursued in support of a number of experiments under development for GAS flights. The program included thirty undergraduate students pursuing major qualifying project work under the guidance of eight faculty supported by a teaching assistant. Both mechanical and electrical engineering students designed and built several microprocessor systems to measure parameters such as temperature, acceleration, pressure, velocity, and circulation in order to determine combustion products, vortex formation, gas entrainment, EMR emissions from thunderstorms, and milli-g-accelerations due to crew motions.

  20. [Spatial and temporal control of ultrasonic fields via optoacoustic holography].

    PubMed

    Gspan, Stefan; Meyer, Alex; Bernet, Stefan; Ritsch-Marte, Monika

    2004-01-01

    The present paper presents a new method for generating ultrasound, based on the interaction of laser-induced ultrasound generation and ultrasonic holography. An ultrasonic field generated in a water tank via the optoacoustic effect is spatially and temporally controlled: In order to produce defined ultrasonic frequencies in the MHz range, the laser pulses incident on a light-absorbing layer are modulated in time using an electro-optic modulator (EOM). Additionally, a high-resolution liquid crystal spatial light modulator (SLM) is used to imprint a pre-calculated phase front to the laser beam. A computer-generated binary hologram is also displayed at the SLM. The expanded laser beam projects the corresponding pattern to the plane absorptive layer in the water tank. The projection of specific patterns for the generation of ultrasonic beams resembles the use of, diffractive optical elements" in optics. Optical ultrasound generation with holographic steering is a flexible tool with promising numerous new applications in medical and technical ultrasound diagnostics. PMID:15462419

  1. Laser ultrasonics evaluation and testing of coated HTR nuclear fuel

    NASA Astrophysics Data System (ADS)

    Amziane, Ahmed; Amari, Mohamed; Mounier, Denis; Breteau, Jean-Marc; Joly, Nicolas; Edely, Mathieu; Larcher, Maxime; Noiré, Paul; Banchet, Julien; Tisseur, David; Gusev, Vitalyi

    2011-05-01

    Laser ultrasonics was applied to the manufacturing control of the quality and integrity (no failure) of coated spherical particles designed for High Temperature Reactors (HTR). The coating of the nuclear fuel kernel is designed to prevent from the diffusion of fission products outside the particle during reactor operation. The quality assessment of the coating layers is of major importance. Using laser ultrasonics, we determined the vibration eigenmodes of dummy HTR particles. The vibration spectrum of a HTR particle provides a non-destructive method of evaluating some important mechanical parameters of the coating. Moreover, without damaging the particle, the laser ultrasonics technique allows to test the presence of a crack in the SiC layer, through the observation of the particle vibration spectrum, which is significantly changed, compared to that of a defect-free particle. We applied nanosecond acoustic pulses, i.e., high frequency laser-generated ultrasound, to measure the acoustic velocity of longitudinal waves the SiC layer. This technique provides an alternative method of evaluation of the Young modulus of the SiC layer. We measure the velocity of surface acoustic waves (SAW) on a pyrocarbon layer cross-section and we demonstrated that the anisotropy of the internal pyrocarbon layer can be evaluated by laser ultrasonics.

  2. An implementation of signal processing algorithms for ultrasonic NDE

    SciTech Connect

    Ericsson, L.; Stepinski, T. [Uppsala Univ. (Sweden). Dept. of Technology, Circuits and Systems

    1994-12-31

    Probability of detection flaws during ultrasonic pulse-echo inspection is often limited by the presence of backscattered echoes from the material structure. A digital signal processing technique for removal of this material noise, referred to as split spectrum processing (SSP), has been developed and verified using laboratory experiments during the last decade. The authors have performed recently a limited scale evaluation of various SSP techniques for ultrasonic signals acquired during the inspection of welds in austenitic steel. They have obtained very encouraging results that indicate promising capabilities of the SSP for inspection of nuclear power plants. Thus, a more extensive investigation of the technique using large amounts of ultrasonic data is motivated. This analysis should employ different combinations of materials, flaws and transducers. Due to the considerable number of ultrasonic signals required to verify the technique for future practical use, a custom-made computer software is necessary. At the request of the Swedish nuclear power industry the authors have developed such a program package. The program provides a user-friendly graphical interface and is intended for processing of B-scan data in a flexible way. Assembled in the program are a number of signal processing algorithms including traditional Split Spectrum Processing and the more recent Cut Spectrum Processing algorithm developed by them. The program and some results obtained using the various algorithms are presented in the paper.

  3. Structural damage identification based on laser ultrasonic propagation imaging technology

    NASA Astrophysics Data System (ADS)

    Chia, Chen-Ciang; Jang, Si-Gwang; Lee, Jung-Ryul; Yoon, Dong-Jin

    2009-06-01

    An ultrasonic propagation imaging (UPI) system consisted of a Q-switched Nd-YAG pulsed laser and a galvanometer laser mirror scanner was developed. The system which requires neither reference data nor fixed focal length could be used for health monitoring of curved structures. If combined with a fiber acoustic wave PZT (FAWPZT) sensor, it could be used to inspect hot target structures that present formidable challenges to the usage of contact piezoelectric transducers mainly due to the operating temperature limitation of transducers and debonding problem due to the mismatch of coefficient of thermal expansion between the target, transducer and bonding material. The inspection of a stainless steel plate with a curvature radius of about 4 m, having 2mm×1mm open-crack was demonstrated at 150°C using a FAWPZT sensor welded on the plate. Highly-curved surfaces scanning capability and adaptivity of the system for large laser incident angle up to 70° was demonstrated on a stainless steel cylinder with 2mm×1mm open-crack. The imaging results were presented in ultrasonic propagation movie which was a moving wavefield emerged from an installed ultrasonic sensor. Damages were localized by the scattering wavefields. The result images enabled easy detection and interpretation of structural defects as anomalies during ultrasonic wave propagation.

  4. Method and apparatus for dual amplitude dual time-of-flight ultrasonic imaging

    NASA Technical Reports Server (NTRS)

    Chern, Engmin James (Inventor); Butler, David W. (Inventor)

    1998-01-01

    A method and apparatus for ultrasonic imaging which includes scanning a test specimen located in a test fixture in a predetermined scan pattern. Propagating and receiving reflected pulses of ultrasonic energy from an ultrasonic transducer directed to a surface of the test specimen. Detecting and generating data of both the amplitude and the depth of a defect in the test specimen from the pulses received from the test specimen. Merging the data of the amplitude and the data of the depth of the defect into composite data and then displaying the composite data in a three dimensional image whereby a mesh of both amplitude and depth data of the defect is displayed in a single image of the defect.

  5. Ultrasonic tomography for in-process measurements of temperature in a multi-phase medium

    DOEpatents

    Beller, Laurence S. (Idaho Falls, ID)

    1993-01-01

    A method and apparatus for the in-process measurement of internal particulate temperature utilizing ultrasonic tomography techniques to determine the speed of sound through a specimen material. Ultrasonic pulses are transmitted through a material, which can be a multi-phase material, over known flight paths and the ultrasonic pulse transit times through all sectors of the specimen are measured to determine the speed of sound. The speed of sound being a function of temperature, it is possible to establish the correlation between speed of sound and temperature, throughout a cross-section of the material, which correlation is programmed into a computer to provide for a continuous in-process measurement of temperature throughout the specimen.

  6. Ultrasonic Evaluation of Deeply Located Trabecular Bones - Preliminary Results

    NASA Astrophysics Data System (ADS)

    Cie?lik, Lucyna; Litniewski, Jerzy

    The analysis of ultrasonic signals scattered by soft tissues have been successfully applied for their characterization. Similarly, the trabecular bone backscattered signal contains information about the properties of the bone structure. Therefore scattering-based ultrasonic technique potentially enables the assessment of microstructure characteristics of a bone. The femoral neck fracture often occurs in the course of osteoporosis and can lead to severe complications. Therefore assessment of femoral bone microstructure and condition is important and essential for the diagnosis and treatment monitoring. As far most of the trabecular bone investigations have been performed in vitro. The only in vivo measurements were carried out in transmission and mostly concerned estimation of the attenuation in heel bone. We have built the ultrasonic scanner that could be useful in acquiring the RF (Radio Frequency) echoes backscattered by the trabecular bone in vivo. Moreover, the bone scanner provides data not only from heel bone but from deeply located bones as well (e.g. femoral bone). It can be also used for easily accessible bones like heel bone or breastbone. In this case a gel-pad is applied to assure focusing of ultrasound in trabecular bone (approximately 10 mm beneath the cortical bone). This study presents preliminary results of the attenuating properties evaluation of trabecular bone from the ultrasonic echoes backscattered by heel bone and femoral neck.

  7. Time-Frequency Analysis of Long Range Ultrasonic Signals

    NASA Astrophysics Data System (ADS)

    Thornicroft, Keith; Mares, Cristinel; Mudge, Peter

    2012-08-01

    Long range ultrasonic testing (LRUT) is a relatively new development within the non-destructive testing sector. Traditionally, conventional ultrasonic testing (UT) is performed at high frequencies, in the MHz range, and is capable of detecting small flaws within a range of millimetres; whereas long range ultrasonic inspection is carried out at lower frequencies, typically between 20 and 100kHz, and is capable of highlighting structural detail and discontinuities tens of metres from a test position. Conventional ultrasonic testing relies on the transmission of bulk waves, the velocities of which are independent of frequency and can usually be predicted easily if the elastic properties of the material under test are known. The dynamics of guided waves, however, are dependent upon frequency making the analysis of received data from a specimen complex. This paper will serve as an introduction to time-frequency representation and may allow a clearer understanding of the non-stationary raw signals produced by this inspection process. Currently, LRUT data are assessed in the time or distance domain using the amplitude vs. time 'A-Scan', therefore structural features and potential flaws are highlighted on a time-of-flight basis. However, as the data obtained are dynamic in time and frequency (non-stationary), time-frequency distributions could provide a mode identification or de-noising process to deal with the problem of coherent noise.

  8. Void detection beneath reinforced concrete sections: The practical application of ground-penetrating radar and ultrasonic techniques

    Microsoft Academic Search

    Nigel J. Cassidy; Rod Eddies; Sam Dods

    2011-01-01

    Ground-penetrating radar (GPR) and ultrasonic ‘pulse echo’ techniques are well-established methods for the imaging, investigation and analysis of steel reinforced concrete structures and are important civil engineering survey tools. GPR is, arguably, the more widely-used technique as it is suitable for a greater range of problem scenarios (i.e., from rebar mapping to moisture content determination). Ultrasonic techniques are traditionally associated

  9. Study on boring hardened materials dryly by ultrasonic vibration cutter

    NASA Astrophysics Data System (ADS)

    Zhang, Jiangzhong; Zhang, Heng; Zhang, Yue

    2011-05-01

    It has been one of the difficulties that high-precision hole on hardened materials is machined. The supersonic vibration boring acoustic system in the lathe in which supersonic wave energy is applied on tool is introduced to create pulse power on the cutting process. The separation vibration cutting is achieved by the pulse force. The comparative tests on boring accuracy and surface quality are carried. The quality of surface machined by this method is compared to that by grinding. This cutting is the green cutting. The boring process system is stability. Under the condition that the cutting speed is less than or equal to 1/3 the tool vibration speed, the cutting force is pulse force and the Cutting energy is of high concentration in time, space and direction. The pulse energy effects on the cutting unit in less than one ten-thousandth second. Traditional cutting of irregular movement elastic compression are eliminated. The cutting force is greatly reduced. The cutting temperature is at room temperature. The tool life is greatly increased. Shape precision and surface quality is greatly improved. The regulations of the ultrasonic vibration boring dry cutting of hardened material are also summarized. The test results show that the ultrasonic vibration cutting tool boring is of very superior cutting mechanism and is a high-precision deep-hole machining of hardened materials, efficient cutting methods.

  10. Study on boring hardened materials dryly by ultrasonic vibration cutter

    NASA Astrophysics Data System (ADS)

    Zhang, Jiangzhong; Zhang, Heng; Zhang, Yue

    2010-12-01

    It has been one of the difficulties that high-precision hole on hardened materials is machined. The supersonic vibration boring acoustic system in the lathe in which supersonic wave energy is applied on tool is introduced to create pulse power on the cutting process. The separation vibration cutting is achieved by the pulse force. The comparative tests on boring accuracy and surface quality are carried. The quality of surface machined by this method is compared to that by grinding. This cutting is the green cutting. The boring process system is stability. Under the condition that the cutting speed is less than or equal to 1/3 the tool vibration speed, the cutting force is pulse force and the Cutting energy is of high concentration in time, space and direction. The pulse energy effects on the cutting unit in less than one ten-thousandth second. Traditional cutting of irregular movement elastic compression are eliminated. The cutting force is greatly reduced. The cutting temperature is at room temperature. The tool life is greatly increased. Shape precision and surface quality is greatly improved. The regulations of the ultrasonic vibration boring dry cutting of hardened material are also summarized. The test results show that the ultrasonic vibration cutting tool boring is of very superior cutting mechanism and is a high-precision deep-hole machining of hardened materials, efficient cutting methods.

  11. Time domain attenuation estimation method from ultrasonic backscattered signals

    PubMed Central

    Ghoshal, Goutam; Oelze, Michael L.

    2012-01-01

    Ultrasonic attenuation is important not only as a parameter for characterizing tissue but also for compensating other parameters that are used to classify tissues. Several techniques have been explored for estimating ultrasonic attenuation from backscattered signals. In the present study, a technique is developed to estimate the local ultrasonic attenuation coefficient by analyzing the time domain backscattered signal. The proposed method incorporates an objective function that combines the diffraction pattern of the source/receiver with the attenuation slope in an integral equation. The technique was assessed through simulations and validated through experiments with a tissue mimicking phantom and fresh rabbit liver samples. The attenuation values estimated using the proposed technique were compared with the attenuation estimated using insertion loss measurements. For a data block size of 15 pulse lengths axially and 15 beamwidths laterally, the mean attenuation estimates from the tissue mimicking phantoms were within 10% of the estimates using insertion loss measurements. With a data block size of 20 pulse lengths axially and 20 beamwidths laterally, the error in the attenuation values estimated from the liver samples were within 10% of the attenuation values estimated from the insertion loss measurements. PMID:22779499

  12. Limitations of forehead pulse oximetry

    Microsoft Academic Search

    Jan S. Jørgensen; Edith R. Schmid; Volker König; Karin Faisst; Albert Huch; Renate Huch

    1995-01-01

    During initial clinical tests to calibrate our reflectance pulse oximetry system, we observed serious physiologic limitations\\u000a to the use of pulse oximetry in the forehead region. We present a case of simultaneous reflectance and transmission mode pulse\\u000a oximetry monitoring in a child undergoing cardiac surgery for congenital cyanotic heart disease with a large intracardiac\\u000a shunt. During general anesthesia, when the

  13. Ultrasonic Technology in Duress Alarms.

    ERIC Educational Resources Information Center

    Lee, Martha A.

    2000-01-01

    Provides the pros and cons of the most commonly used technologies in personal duress alarm systems in the school environment. Discussed are radio frequency devices, infrared systems, and ultrasonic technology. (GR)

  14. SAW propagation on cylindrical parts using laser-ultrasonics: application to crack detection

    Microsoft Academic Search

    D. Clorennec; D. Royer; S. Catheline

    2002-01-01

    We applied the laser-ultrasonic technique for detecting surface breaking slots in steel or duraluminurn cylinders. Surface acoustic waves (SAW) are launched by a pulsed YAG laser focused along a line. The radial component of the displacement is measured by a heterodyne optical interferometer. In the first experiment, we study the evolution of Rayleigh waveforms with the angle ? between the

  15. A new focusing ultrasonic transducer and two foci acoustic lens for acoustic microscopy

    Microsoft Academic Search

    Konstantin I. Maslov; Leonid M. Dorozhkin; Valery S. Doroshenko; Roman G. Maev

    1997-01-01

    The textured piezoelectric film of a new organic-based material produced by vapor deposition was used as an active element of a focusing ultrasonic transducer. The transducer exhibits near theoretical lateral and axial resolution, unipolar pulse response to a step voltage, and 30 dB insertion losses in an octave frequency band. The transducer is acoustically transparent over a wide frequency range

  16. Ultrasonic Tissue Characterization of Atherosclerosis by a Speed-of-Sound Microscanning System

    Microsoft Academic Search

    Yoshifumi Saijo; Esmeraldo Santos Filho; Hidehiko Sasaki; Tomoyuki Yambe; Motonao Tanaka; Naohiro Hozumi; Kazuto Kobayashi; Nagaya Okada

    2007-01-01

    We have been developing a scanning acoustic microscope (SAM) system for medicine and biology featuring quantitative measurement of ultrasonic parameters of soft tissues. In the present study, we propose a new concept sound speed microscopy that can measure the thickness and speed of sound in the tissue using fast Fourier transform of a single pulsed wave instead of burst waves

  17. Ultrasonic imaging of the group velocity surface about the cubic axis in silicon

    Microsoft Academic Search

    Kwang Yul Kim; Kathleen C. Bretz; Arthur G. Every; Wolfgang Sachse

    1996-01-01

    This article reports measurements of the group velocity surface of silicon in the region of the ?100? axis. Pulsed ultrasonic beams generated by a piezoelectric longitudinal mode transducer are transmitted through water and focused onto a small spot on the surface of a (001) oriented silicon single crystal disk. This gives rise to transient elastic waves which propagate in a

  18. Ultrasonic Frost Suppression

    NASA Astrophysics Data System (ADS)

    Adachi, Kazunari; Saiki, Kazushi; Sato, Hiroki; Ito, Takahiro

    2003-02-01

    The authors have observed the accumulation of frost on the surface of a rectangular aluminum alloy (duralumin) plate flexurally vibrating at approximately 37 kHz in an atmosphere of almost 100% relative humidity at 2°C. The plate surface, which had been prepolished with abrasive slurry for maintaining its average surface roughness of about 100 nm, was refrigerated at a temperature of -20°C with cold carbon-dioxide gas as coolant. Experiments have been conducted with and without fine silver oxide powder spread on the plate surface so as to examine the effect of artificial ice crystal nuclei. Ultrasonic vibrations with an amplitude of 3.4 ?m (rms) are found to suppress frost accumulation by approximately 60%. The phenomenon cannot be ascribed directly to the heat generation caused by high-amplitude vibration, but may have a complex mechanical and/or acoustical effect on small ice crystals.

  19. The acousto-ultrasonic approach

    NASA Technical Reports Server (NTRS)

    Vary, Alex

    1987-01-01

    The nature and underlying rationale of the acousto-ultrasonic approach is reviewed, needed advanced signal analysis and evaluation methods suggested, and application potentials discussed. Acousto-ultrasonics is an NDE technique combining aspects of acoustic emission methodology with ultrasonic simulation of stress waves. This approach uses analysis of simulated stress waves for detecting and mapping variations of mechanical properties. Unlike most NDE, acousto-ultrasonics is less concerned with flaw detection than with the assessment of the collective effects of various flaws and material anomalies. Acousto-ultrasonics has been applied chiefly to laminated and filament-wound fiber reinforced composites. It has been used to assess the significant strength and toughness reducing effects that can be wrought by combinations of essentially minor flaws and diffuse flaw populations. Acousto-ultrasonics assesses integrated defect states and the resultant variations in properties such as tensile, shear, and flexural strengths and fracture resistance. Matrix cure state, porosity, fiber orientation, fiber volume fraction, fiber-matrix bonding, and interlaminar bond quality are underlying factors.

  20. An evaluation of effective radiuses of bulk-wave ultrasonic transducers as circular piston sources for accurate velocity measurements

    Microsoft Academic Search

    Mototaka Arakawa; Jun-ichi Kushibiki; Naoya Aoki

    2004-01-01

    The effective radius of a bulk-wave ultrasonic transducer as a circular piston source, fabricated on one end of a synthetic silica (SiO2) glass buffer rod, was evaluated for accurate velocity measurements of dispersive specimens over a wide frequency range. The effective radius was determined by comparing measured and calculated phase variations due to diffraction in an ultrasonic transmission line of

  1. Ultrasonically treated multi-walled carbon nanotubes (MWCNTs) as PtRu catalyst supports for methanol electrooxidation

    Microsoft Academic Search

    Chunwei Yang; Xinguo Hu; Dianlong Wang; Changsong Dai; Liang Zhang; Haibo Jin; Simeon Agathopoulos

    2006-01-01

    In the quest of fabricating supported catalysts, experimental results of transmission electron microscopy, Raman and infrared spectroscopy indicate that ultrasonic treatment effectively functionalizes multi-walled carbon nanotubes (MWCNTs), endowing them with groups that can act as nucleation sites which can favor well-dispersed depositions of PtRu clusters on their surface. Ultrasonic treatment seems to be superior than functionalization via regular refluxing. This

  2. Ultrasonic monitoring of asymmetric carbon fibre reinforced aluminum laminates

    NASA Astrophysics Data System (ADS)

    Zhao, Junqing; Yang, Fan; Wang, Rongguo

    2013-08-01

    Asymmetric carbon fibre reinforced aluminum alloy laminates was manufactured for the purpose with repeat tensile test, which will be applied in composite pressure vessel. Ultrasonic C scan and A scan approach are used to evaluate the damage of the asymmetric CFRP-Al (carbon fibre reinforced aluminum alloy) laminates. Nondestructive detection is carried out for the CFRP-Al laminates before and after tensile test. Comparison results and pulse echo analysis show that when subjected to repeat tensile test with 70% elastic limit strain load of the CFRP laminates, the interface debonding between CFRP and Al will not occur but the delamination within CFRP laminates becomes the main damage of the asymmetric CFRP-Al laminates. This investigation indicated that combined ultrasonic C scan and A scan is available for damage evaluation of fibre metal laminates.

  3. Ultrasonic testing of concrete using split spectrum processing

    SciTech Connect

    Karaoguz, M.; Bilguetay, N.; Akguel, T.; Popovics, S.

    1999-11-01

    In this paper, the authors present results for nondestructive testing of concrete using ultrasonic pulse echo techniques to detect and localize discontinuities which may cause critical infrastructure problems. Concrete is a highly attenuating medium and only limited penetration can be obtained using high frequency ultrasonic signals. However, even when sufficient penetration is achieved, significant background noise due to randomly distributed scatterers can corrupt the echoes from discontinuities. They apply split spectrum processing (SSP) technique to distinguish flaw signals from the background microstructure noise corresponding to complex, dispersive and nonhomogeneous reflectors. The experimental results are obtained for different types of concrete, using transducers with center frequencies of up to 1 MHz. Experimental data from concrete samples such as mortar, with and without discontinuities, and other concrete specimens using transducers with 0.25, 0.5, and 1 MHz center frequencies demonstrate SSPs noise reduction and discontinuity detection capabilities.

  4. Assessment of ultrasonic NDT methods for high speed rail inspection

    NASA Astrophysics Data System (ADS)

    Cheng, Jianzheng; Bond, Leonard J.

    2015-03-01

    This article reviews some new ultrasonic rail inspection methods emerging in recent years. It focuses on the state of the art for guided wave technologies and their potential use for used for rail inspection. It considers ultrasound transduction options including EMATs, air coupled, pulsed laser and wheel probe guided wave methods. It compares performances in terms of frequency ranges, energy delivered, ultrasonic wave modes excited, sensitivity, potential speeds of inspection, inspection regions, transducer angle and positioning. The advantages and disadvantages of each transduction modality for possible use in high speed railway are discussed. It is concluded that an EMAT and laser method, or their combination has the potential to provide a new tool for higher speed rail in-service inspection.

  5. Non-Contact Ultrasonic Characterization of Defects Using EMATs

    NASA Astrophysics Data System (ADS)

    Edwards, R. S.; Dixon, S.; Jian, X.

    2005-04-01

    We have developed a non-contact ultrasonic technique for detecting and gauging the depth of surface and subsurface defects in metals. A low-frequency broadband Rayleigh-wave pulse is generated and detected by two electro-magnetic acoustic transducers (EMATs) held at a standoff of up to 5 mm, with laser generation and detection also possible. This technique has applications for online testing such as rail track inspection, where faster speeds than with conventional contact ultrasonic techniques should be possible. We describe experiments gauging the position and depth of cracks by measuring the change in signal amplitude and frequency content with the EMATs on either side of the defect, or by looking for an enhancement of the signal close to the defect.

  6. Ultrasonic probe of the AuZn Fermi surface.

    SciTech Connect

    Svitelskiy, O. (Oleksiy); Suslov, A. V. (Alexey V.); Singleton, J. M. (John M.); Lashley, J. C. (Jason C.)

    2005-01-01

    We, for the first time, apply the ultrasonic pulse-echo technique to explore the Fermi surface of the martensite phase of the single crystalline AuZn shape memory alloy. The ultrasonic measurements were performed in the magnetic fields of up to 45 T in the temperature range of 0.07 < T < 300 K. In the martensite phase (T < 64 K), the oscillations of the speed of the longitudinal sound wave propagating in the (110) direction indicated a strong acoustic de Haas - van Alphen effect. In addition to the earlier described oscillations with frequencies of 1140 and 4720 Tesla, we observed a new frequency of 120 Tesla, which was predicted theoretically. Corresponding effective masses were in favorable agreement with those expected from band structure calculations.

  7. Effect of experimental conditions on acousto-ultrasonic reproducibility

    NASA Astrophysics Data System (ADS)

    Gyekenyesi, Andrew L.; Harmon, Laura M.; Kautz, Harold E.

    2002-06-01

    Acousto-ultrasonics (AU) is a nondestructive evaluation (NDE) technique that utilizes two ultrasonic transducers to interrogate the condition of a test specimen. The sending transducer introduces an ultrasonic pulse at a point on the surface of the specimen while a receiving transducer detects the signal after it has passed through the material. The aim of the method is to correlate certain parameters of the detected waveform to characteristics of the material between the two transducers. The waveform parameter of interest is the attenuation due to internal damping for which information is being garnered from the frequency domain. The parameters utilized to indirectly quantify the attenuation are the ultrasonic decay rate as well as various moments of the frequency power spectrum. Here, the sensitivity for each of the parameters was assessed in respect to changing boundary conditions during the experiments. Three conditions were controlled during the ultrasonic characterization of the specimens. First, issues concerning the contact force of the transducer were studied. Second, the support structure of the specimen was addressed. Lastly, the damage state of the material itself was considered. After analyzing the various AU parameters, the overall sensitivity of the AU technique to material change or damage were quantified and compared to changes in the AU values resulting from the experimental boundary conditions. This investigation showed that certain AU parameters could be utilized to gauge damage in composites, although, the experimental boundary conditions may slightly influence the results. The results of this study are important due to the fact that at this point AU is an empirical method.

  8. A web-based tutorial for ultrasonic attenuation measurement

    NASA Astrophysics Data System (ADS)

    Margetan, Frank J.; Barnard, Dan; Orman, David; Feygin, Alex; Pavel, Brittney

    2014-02-01

    An ultrasonic attenuation-versus-frequency curve can serve as an "ultrasonic signature" which may be correlated with microstructural properties of interest such as grain size in metals or porosity level in composites. Attenuation also plays a role in ultrasonic inspections and is consequently a key input into many inspection simulation models. A web-based self-tutorial on practical attenuation measurements is under development. The focus is on pulse/echo immersion measurements made using a broadband transducer to deduce attenuation within the transducer's useable bandwidth. Two approaches are considered: one using a calibration specimen having a known attenuation curve, and one without. In the first approach a back-wall (BW) echo in the calibration specimen is compared with a BW echo in the test specimen. In the second approach various BW reverberation echoes in the test specimen are compared with one another or with a front-wall echo. The web-based tutorial incorporates three classes of materials. The first includes written documentation and videos describing the measurement setups, the data-acquisition and analysis procedures, and the underlying models use to analyze the raw UT data. Secondly, general purpose "stand-alone" data-analysis software is supplied that is designed to be used with any ultrasonic inspection system that can output A-scan data as a text file. This includes both FORTRAN software and Excel spreadsheet calculators that accept A-scan text data as inputs. Thirdly, we supply demonstration software where the data acquisition and analysis procedures are integrated with a specific class of commercial ultrasonic test instruments, namely those running UTEX Winpect control software. This paper provides an overview of the measurement methods and tutorial materials. We also present early results from round-robin trials in which selected metal and composite specimens are being sent to participating partners for attenuation measurement.

  9. Repeat scanning technology for laser ultrasonic propagation imaging

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Ryul; Yenn Chong, See; Sunuwar, Nitam; Park, Chan Yik

    2013-08-01

    Laser ultrasonic scanning in combination with contact or non-contact sensors provides new paradigms in structural health management (SHM) and non-destructive in-process quality control (IPQC) for large composite structures. Wave propagation imaging technology based on laser ultrasonic scanning and fixed-point sensing shows remarkable advantages, such as minimal need for embedded sensors in SHM, minimum invasive defect visualization in IPQC and general capabilities of curved and complex target inspection, and temporal reference-free inspection. However, as with other SHM methods and non-destructive evaluation based on ultrasound, the signal-to-noise ratio (SNR) is a prevalent issue in real structural applications, especially with non-contact thin-composite sensing or with thick and heterogeneous composites. This study proposes a high-speed repeat scanning technique for laser ultrasonic propagation imaging (UPI) technology, which is realized with the scanning speed of 1 kHz of a Q-switched continuous wave laser, and precise control of the laser beam pulses for identical point scanning. As a result, the technique enables the achievement of significant improvement in the SNR to inspect real-world composite structures. The proposed technique provides enhanced results for impact damage detection in a 2 mm thick wing box made of carbon-fiber-reinforced plastic, despite the low sensitivity of non-contact laser ultrasonic sensing. A field-applicable pure laser UPI system has been developed using a laser Doppler vibrometer as the non-contact ultrasonic sensor. The proposed technique enables the visualization of the disbond defect in a 15 mm thick wind blade specimen made of glass-fiber-reinforced plastic, despite the high dissipation of ultrasound in the thick composite.

  10. Transmission Communication

    E-print Network

    Chen, Sheng

    ELEC3028 Digital Transmission -- MODEM S Chen Digital Communication System . Purpose: communicate: rate, quality # spectral bandwidth requirement . Major components: CODEC, MODEM and channel modulation input output CODEC MODEM Medium 1 #12; ELEC3028 Digital Transmission -- MODEM S Chen Digital

  11. AQUIFER TRANSMISSIVITY

    EPA Science Inventory

    Evaluation of groundwater resources requires the knowledge of the capacity of aquifers to store and transmit ground water. This requires estimates of key hydraulic parameters, such as the transmissivity, among others. The transmissivity T (m2/sec) is a hydrauli...

  12. Capacitive micromachined ultrasonic transducers with piston-shaped membranes: fabrication and experimental characterization

    Microsoft Academic Search

    Yongli Huang; Xuefeng Zhuang; E. Hggstrom; A. Ergun; Ching-Hsiang Cheng; B. Khuri-Yakub

    2009-01-01

    Capacitive micromachined ultrasonic transducers (CMUTs) featuring piston-shaped membranes (piston CMUTs) were developed to improve device performance in terms of transmission efficiency, reception sensitivity, and fractional bandwidth (FBW). A piston CMUT has a relatively flat active moving surface whose membrane motion is closer to ideal piston-type motion compared with a CMUT with uniformly thick membranes (classical CMUT). Piston CMUTs with a

  13. Ultrasonic transducers for cure monitoring: design, modelling and validation

    NASA Astrophysics Data System (ADS)

    Lionetto, Francesca; Montagna, Francesco; Maffezzoli, Alfonso

    2011-12-01

    The finite element method (FEM) has been applied to simulate the ultrasonic wave propagation in a multilayered transducer, expressly designed for high-frequency dynamic mechanical analysis of polymers. The FEM model includes an electro-acoustic (active element) and some acoustic (passive elements) transmission lines. The simulation of the acoustic propagation accounts for the interaction between the piezoceramic and the materials in the buffer rod and backing, and the coupling between the electric and mechanical properties of the piezoelectric material. As a result of the simulations, the geometry and size of the modelled ultrasonic transducer has been optimized and used for the realization of a prototype transducer for cure monitoring. The transducer performance has been validated by measuring the velocity changes during the polymerization of a thermosetting matrix of composite materials.

  14. Study on Multi-DOF Ultrasonic Actuator for Laparoscopic Instrument

    NASA Astrophysics Data System (ADS)

    Park, Shinsuk; Takemura, Kenjiro; Maeno, Takashi

    In surgical robots, compact manipulators with multi-degree-of-freedom (DOF) are essential owing to a small work volume in the patient body. Conventional single-DOF actuators such as electromagnetic motors require a multiple number of actuators to generate multi-DOF motion, which in turn results in bulky mechanism combined with transmission device. Our previous work has developed a compact ultrasonic motor capable of generating a multi-DOF rotation of a spherical rotor utilizing three natural vibration modes of a bar-shaped stator. The present study designs and builds a novel multi-DOF master-slave system for laparoscopic surgical procedures, using a single ultrasonic actuator. The system consists of surgical forceps on multi-DOF wrist with joystick controller. Experimental results have confirmed high responsiveness and precise position control of the master-slave system.

  15. Magnetic and ultrasonic studies on stable cobalt ferrite magnetic nanofluid.

    PubMed

    Nabeel Rashin, M; Hemalatha, J

    2014-03-01

    Stable cobalt ferrite nanofluids of various concentrations have been prepared through co-precipitation method. Structural and morphological studies of nanoparticles are made with the help of X-ray diffraction technique and Transmission Electron Microscope respectively and it is found that the particles exhibit face centered cubic structure with an average size of 14 nm. The magnetic properties of the nanofluids have been analyzed at room temperature which revealed ferromagnetic behavior and also the very low value of coupling constant which ensures the negligible interparticle interaction in the absence of magnetic field. Ultrasonic investigations have been made for the nanofluids at different temperatures and magnetic fields. The temperature effects are explained with the help of open and close-packed water structure. The inter particle interactions of surface modified CoFe2O4 particles and the cluster formation at higher concentrations are realized through the variations in ultrasonic parameters. PMID:24188514

  16. Recovery of the parameters of cancellous bone by inversion of effective velocities, and transmission and reflection coefficients

    NASA Astrophysics Data System (ADS)

    Buchanan, James L.; Gilbert, Robert P.; Ou, Miao-jung Y.

    2011-12-01

    Estimating the parameters of an elastic or poroelastic medium from reflected or transmitted acoustic data is an important but difficult problem. Use of the Nelder-Mead simplex method to minimize an objective function measuring the discrepancy between some observable and its value calculated from a model for a trial set of parameters has been tried by several authors. In this paper, the difficulty with this direct approach, which is the existence of numerous local minima of the objective function, is documented for the in vitro experiment in which a specimen in a water tank is subject to an ultrasonic pulse. An indirect approach, based on the numerical solution of the equations for a set of ‘effective’ velocities and transmission coefficients, is then observed empirically to ameliorate the difficulties posed by the direct approach.

  17. Pulse Oximetry

    MedlinePLUS

    ... Society Pulse Oximetry amount of gases (oxygen and carbon dioxide) that are in your blood. To get ... Also, a pulse oximeter does not measure your carbon dioxide level. How accurate is the pulse oximeter? ...

  18. 21 CFR 872.4850 - Ultrasonic scaler.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4850 Ultrasonic...ultrasonic scaler is a device intended for use during dental cleaning and periodontal (gum) therapy to...

  19. 21 CFR 872.4850 - Ultrasonic scaler.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4850 Ultrasonic...ultrasonic scaler is a device intended for use during dental cleaning and periodontal (gum) therapy to...

  20. 21 CFR 872.4850 - Ultrasonic scaler.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4850 Ultrasonic...ultrasonic scaler is a device intended for use during dental cleaning and periodontal (gum) therapy to...

  1. 21 CFR 872.4850 - Ultrasonic scaler.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4850 Ultrasonic...ultrasonic scaler is a device intended for use during dental cleaning and periodontal (gum) therapy to...

  2. 21 CFR 872.4850 - Ultrasonic scaler.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4850 Ultrasonic...ultrasonic scaler is a device intended for use during dental cleaning and periodontal (gum) therapy to...

  3. 21 CFR 890.5300 - Ultrasonic diathermy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5300 Ultrasonic diathermy. (a) Ultrasonic diathermy for use in...

  4. Ultrasonic cure monitoring of advanced composites

    SciTech Connect

    Shepard, D.D.; Smith, K.R.

    1997-12-31

    Measurements of the ultrasonic sound speed of thermosetting resins and composites can be used as an in-process cure monitoring technique. Ultrasonic measurements have an advantage over other in-process techniques in that ultrasonic sensors do not make contact with the part (thus leaving no imbedded sensor or witness mark) and can make true bulk measurements of the part. A new commercially available ultrasonic cure monitoring system for the cure monitoring of thermosetting resins and composites has been developed. Advancements in ultrasonic sensor technology enable the self-contained ultrasonic sensor to be easily installed in a mold and maintain good coupling to the part during thermal cycling to 260{degrees}C. Data is presented showing the chance in ultrasonic sound speed during the compression molding of epoxy prepregs. The data shows a good relationship to the electrical resistivity data collected via dielectric cure monitoring. The ultrasonic technique is also applicable to phenolic based materials.

  5. NDE application of ultrasonic tomography to a full-scale concrete structure.

    PubMed

    Choi, Hajin; Popovics, John S

    2015-06-01

    Newly developed ultrasonic imaging technology for large concrete elements, based on tomographic reconstruction, is presented. The developed 3-D internal images (velocity tomograms) are used to detect internal defects (polystyrene foam and pre-cracked concrete prisms) that represent structural damage within a large steel reinforced concrete element. A hybrid air-coupled/contact transducer system is deployed. Electrostatic air-coupled transducers are used to generate ultrasonic energy and contact accelerometers are attached on the opposing side of the concrete element to detect the ultrasonic pulses. The developed hybrid testing setup enables collection of a large amount of high-quality, through-thickness ultrasonic data without surface preparation to the concrete. The algebraic reconstruction technique is used to reconstruct p-wave velocity tomograms from the obtained time signal data. A comparison with a one-sided ultrasonic imaging method is presented for the same specimen. Through-thickness tomography shows some benefit over one-sided imaging for highly reinforced concrete elements. The results demonstrate that the proposed through-thickness ultrasonic technique shows great potential for evaluation of full-scale concrete structures in the field. PMID:26067042

  6. Novel Real-Time Temperature Diagnosis of Conventional Hot-Embossing Process Using an Ultrasonic Transducer

    PubMed Central

    Cheng, Chin-Chi; Yang, Sen-Yeu; Lee, Dasheng

    2014-01-01

    This paper presents an integrated high temperature ultrasonic transducer (HTUT) on a sensor insert and its application for real-time diagnostics of the conventional hot embossing process to fabricate V-cut patterns. The sensor was directly deposited onto the sensor insert of the hot embossing mold by using a sol-gel spray technique. It could operate at temperatures higher than 400 °C and uses an ultrasonic pulse-echo technique. The ultrasonic velocity could indicate the three statuses of the hot embossing process and also evaluate the replication of V-cut patterns on a plastic plate under various processing conditions. The progression of the process, including mold closure, plastic plate softening, cooling and plate detachment inside the mold, was clearly observed using ultrasound. For an ultrasonic velocity range from 2197.4 to 2435.9 m/s, the height of the V-cut pattern decreased from 23.0 to 3.2 ?m linearly, with a ratio of ?0.078 ?m/(m/s). The incompleteness of the replication of the V-cut patterns could be indirectly observed by the ultrasonic signals. This study demonstrates the effectiveness of the ultrasonic sensors and technology for diagnosing the replicating condition of microstructures during the conventional hot embossing process. PMID:25330051

  7. LASER-ULTRASONIC TESTING AND ITS APPLICATIONS TO NUCLEAR REACTOR INTERNALS

    SciTech Connect

    Ochiai, M.; Miura, T. [Power and Industrial Sys. R and D Center, Toshiba Corp., 8, Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa 235-8523 (Japan); Yamamoto, S. [Isogo Nuclear Engineering Center, Toshiba Corp., 8, Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa 235-8523 (Japan)

    2008-02-28

    A new nondestructive testing technique for surface-breaking microcracks in nuclear reactor components based on laser-ultrasonics is developed. Surface acoustic wave generated by Q-switched Nd:YAG laser and detected by frequency-stabilized long pulse laser coupled with confocal Fabry-Perot interferometer is used to detect and size the cracks. A frequency-domain signal processing is developed to realize accurate sizing capability. The laser-ultrasonic testing allows the detection of surface-breaking microcrack having a depth of less than 0.1 mm, and the measurement of their depth with an accuracy of 0.2 mm when the depth exceeds 0.5 mm including stress corrosion cracking. The laser-ultrasonic testing system combined with laser peening system, which is another laser-based maintenance technology to improve surface stress, for inner surface of small diameter tube is developed. The generation laser in the laser-ultrasonic testing system can be identical to the laser source of the laser peening. As an example operation of the system, the system firstly works as the laser-ultrasonic testing mode and tests the inner surface of the tube. If no cracks are detected, the system then changes its work mode to the laser peening and improves surface stress to prevent crack initiation. The first nuclear industrial application of the laser-ultrasonic testing system combined with the laser peening was completed in Japanese nuclear power plant in December 2004.

  8. Health monitoring of complex curved structures using an ultrasonic wavefield propagation imaging system

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Ryul; Takatsubo, Junji; Toyama, Nobuyuki; Kang, Dong-Hoon

    2007-12-01

    An ultrasonic wavefield propagation imaging system is introduced and then applied for ultrasonic wavefield imaging of complex curved surfaces. A Q-switched pulsed laser is utilized as a moving ultrasonic generator, and a PZT ultrasonic sensor is fixed during the laser beam scanning and detects the ultrasonic waves propagated from the points excited by the laser beam. The waveforms are allocated in the spatial domain of the scanned points and then manipulated in the form of a time versus wavefield movie. The visualized wavefields enable easy detection and interpretation of structural defects because anomalies during wavefield propagation can be visualized. Furthermore, this ultrasonic wavefield propagation imaging system enables reference-free inspection, complex curved surface scanning because it does not require control of focal length and incidence angle of the laser beam, and excellent adaptability with built-in structural health monitoring sensors, such as piezoelectric and fiber optic sensors. The system is demonstrated in the applications of wavefield visualization on a drill surface, detection of mass loss parts inside an elbow pipe joint, and detection and characterization of impact damage and stringer disbond in a composite skin-stringer structure.

  9. Ultrasonic stir welding process and apparatus

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2009-01-01

    An ultrasonic stir welding device provides a method and apparatus for elevating the temperature of a work piece utilizing at least one ultrasonic heater. Instead of relying on a rotating shoulder to provide heat to a workpiece an ultrasonic heater is utilized to provide ultrasonic energy to the workpiece. A rotating pin driven by a motor assembly performs the weld on the workpiece. A handheld version can be constructed as well as a fixedly mounted embodiment.

  10. Rolling dry-coupled transducers for ultrasonic inspections of aging aircraft structures

    NASA Astrophysics Data System (ADS)

    Komsky, Igor N.

    2004-07-01

    Some advanced aircraft materials or coatings are porous or otherwise sensitive to the application of water, gel, or some other ultrasonic couplants. To overcome the problems associated with the liquid coupling medium, dry-coupled rolling modules were developed at Northwestern University for the transmission of both longitudinal and transverse ultrasonic waves at frequencies up to 10 MHz. Dry-coupled ultrasonic modules contain solid core internal stators and solid or flexible external rotors with the flexible polymer substrates. Two types of the dry-coupled modules are under development. Cylindrical base transducer modules include solid core cylindrical rotors with flexible polymer substrates that rotate around the stators with ultrasonic elements. Dry-coupled modules with elongated bases contain solid core stators and flexible track-like polymer substrates that rotate around the stators as rotors of the modules. The elongated base modules have larger contact interfaces with the inspection surface in comparison with the cylindrical base modules. Some designs of the dry-coupled rolling modules contain several ultrasonic elements with different incident angles or a variable angle unit for rapid adjustments of incident angles. The prototype dry-coupled rolling modules were integrated with the portable ultrasonic inspection systems and tested on a number of Boeing aircraft structures.

  11. Nondestructive ultrasonic determination of avocado softening process

    Microsoft Academic Search

    Amos Mizrach; Uri Flitsanov

    1999-01-01

    A testing technique based on a new nondestructive ultrasonic device was applied to a whole avocado fruit to measure its internal changes during ripening and to assess its quality. The method was based on local measurements of ultrasonic wave velocity and attenuation, by means of two inclined ultrasonic probes, which were moved across the fruit peel. Multiple readings of wave

  12. On ultrasonic detection of surface features

    Microsoft Academic Search

    Michael K. Brown

    1986-01-01

    Ultrasonic range finding is an inexpensive means of obtaining 3-dimensional information about the surrounding environment. Because of this ultrasonic detection methods have received considerable attention recently, particularly in the robotic community. Unfortunately, ultrasonic range finding suffers from shortcomings that are not found in more expensive techniques such as laser range finding. For example, a laser range finder can determine both

  13. Pitch-catch only ultrasonic fluid densitometer

    DOEpatents

    Greenwood, Margaret S. (Richland, WA); Harris, Robert V. (Pasco, WA)

    1999-01-01

    The present invention is an ultrasonic fluid densitometer that uses a material wedge and pitch-catch only ultrasonic transducers for transmitting and receiving ultrasonic signals internally reflected within the material wedge. Density of a fluid is determined by immersing the wedge into the fluid and measuring reflection of ultrasound at the wedge-fluid interface.

  14. Magnetostrictive materials and ultrasonics

    SciTech Connect

    Hansen, T.T.

    1996-08-01

    In the early 1970s a group of Navy scientists led by A.E. Clark began experimenting with highly magnetostrictive rare earth metals, substances that would lengthen in response to a magnetic field. By 1976 the group had discovered an alloy of iron and terbium that exhibited tremendous levels of magnetostriction. They also discovered that, by adding dysprosium, they could lessen the degree of anisotropy in the magnetization of the alloy. Clark named the new material Terfenol-D after terbium, iron, the Naval Ordinance Lab, and dysprosium. Because Terfenol-D was originally developed for sonar applications, it was regarded as usable at low frequencies only from direct current (dc) to 2 kHz. Furthermore, eddy current activity was believed to be so great that high-frequency operation was deemed impractical. However, Terfenol-D can be used into the ultrasonic frequency range. It exhibits the greatest magnetostrictive effects of any commercially available material and is now positioned for a wide range of high-frequency uses--in which piezoceramic materials were formerly used exclusively. The authors have harnessed the energy efficiency of this alloy and discuss the use of this material in actuators.

  15. Ultrasonic Time Reversal Mirrors

    NASA Astrophysics Data System (ADS)

    Fink, Mathias; Montaldo, Gabriel; Tanter, Mickael

    2004-11-01

    For more than ten years, time reversal techniques have been developed in many different fields of applications including detection of defects in solids, underwater acoustics, room acoustics and also ultrasound medical imaging and therapy. The essential property that makes time reversed acoustics possible is that the underlying physical process of wave propagation would be unchanged if time were reversed. In a non dissipative medium, the equations governing the waves guarantee that for every burst of sound that diverges from a source there exists in theory a set of waves that would precisely retrace the path of the sound back to the source. If the source is pointlike, this allows focusing back on the source whatever the medium complexity. For this reason, time reversal represents a very powerful adaptive focusing technique for complex media. The generation of this reconverging wave can be achieved by using Time Reversal Mirrors (TRM). It is made of arrays of ultrasonic reversible piezoelectric transducers that can record the wavefield coming from the sources and send back its time-reversed version in the medium. It relies on the use of fully programmable multi-channel electronics. In this paper we present some applications of iterative time reversal mirrors to target detection in medical applications.

  16. Ultra-short pulse generator

    DOEpatents

    McEwan, Thomas E. (Livermore, CA)

    1993-01-01

    An inexpensive pulse generating circuit is disclosed that generates ultra-short, 200 picosecond, and high voltage 100 kW, pulses suitable for wideband radar and other wideband applications. The circuit implements a nonlinear transmission line with series inductors and variable capacitors coupled to ground made from reverse biased diodes to sharpen and increase the amplitude of a high-voltage power MOSFET driver input pulse until it causes non-destructive transit time breakdown in a final avalanche shockwave diode, which increases and sharpens the pulse even more.

  17. Ultra-short pulse generator

    DOEpatents

    McEwan, T.E.

    1993-12-28

    An inexpensive pulse generating circuit is disclosed that generates ultra-short, 200 picosecond, and high voltage 100 kW, pulses suitable for wideband radar and other wideband applications. The circuit implements a nonlinear transmission line with series inductors and variable capacitors coupled to ground made from reverse biased diodes to sharpen and increase the amplitude of a high-voltage power MOSFET driver input pulse until it causes non-destructive transit time breakdown in a final avalanche shock wave diode, which increases and sharpens the pulse even more. 5 figures.

  18. System and technique for characterizing fluids using ultrasonic diffraction grating spectroscopy

    DOEpatents

    Greenwood, Margaret S.

    2005-04-12

    A system for determining a property of a fluid based on ultrasonic diffraction grating spectroscopy includes a diffraction grating on a solid in contact with the fluid. An interrogation device delivers ultrasound through the solid and a captures a reflection spectrum from the diffraction grating. The reflection spectrum including a diffraction order equal to zero exhibits a peak whose location is used to determine speed of sound in the fluid. A separate measurement of the acoustic impedance is combined with the determined speed of sound to yield a measure of fluid density. A system for determining acoustic impedance includes an ultrasonic transducer on a first surface of a solid member, and an opposed second surface of the member is in contact with a fluid to be monitored. A longitudinal ultrasonic pulse is delivered through the solid member, and a multiplicity of pulse echoes caused by reflections of the ultrasonic pulse between the solid-fluid interface and the transducer-solid interface are detected. The decay rate of the detected echo amplitude as a function of echo number is used to determine acoustic impedance.

  19. Ultrasonic velocity in water-ethanol-sucrose mixtures during alcoholic fermentation.

    PubMed

    Resa, P; Elvira, L; Montero de Espinosa, F; Gómez-Ullate, Y

    2005-02-01

    During alcoholic fermentation, sucrose and water are transformed into ethanol and carbon dioxide by the action of yeast enzymes. The measurement of the velocity of an ultrasonic pulse travelling through a fermentation tank can be used to characterize the state of the process. In this work, an experimental study of the density and ultrasonic velocity in the ternary mixture (water-ethanol-saccharose) is presented. Experimental results were compared to ideal density and to commonly used expressions of the sound velocity in liquid mixtures (Urick, Natta-Baccaredda and Nomoto). A semiempirical approach was proposed to improve the efficiency of theoretical models when dealing with mixtures of associated liquids. PMID:15567201

  20. Ultrasonic velocity measurement using phase-slope cross-correlation methods

    NASA Technical Reports Server (NTRS)

    Hull, D. R.; Kautz, H. E.; Vary, A.

    1984-01-01

    Computer implemented phase-slope and cross-correlation methods are introduced for measuring time delays between pairs of broadband ultrasonic pulse-echo signals for determining velocity in engineering materials. The phase-slope and cross-correlation methods are compared with the overlap method which is currently in wide use. Comparison of digital versions of the three methods shows similar results for most materials having low ultrasonic attenuation. However, the cross-correlation method is preferred for highly attenuating materials. An analytical basis for the cross-correlation method is presented. Examples are given for the three methods investigated to measure velocity in representative materials in the megahertz range.

  1. Piezoelectric thick film ultrasonic transducers fabricated by a sol-gel spray technique.

    PubMed

    Kobayashi, M; Olding, T R; Sayer, M; Jen, C K

    2002-10-01

    Thick film broadband ultrasonic transducers (UTs) produced by a sol-gel spray technique and operated below 10 MHz are presented. These UTs are formed by dispersing PZT and LiTaO3 particles, respectively in Al2O3 and PZT sol-gel solution. The 50-100 microm thick films have been deposited on curved steel, flat steel and aluminum substrates and steel rods. Ultrasonic pulse-echo signals with a signal to noise ratio of more than 25 dB are experimentally obtained for the operating temperatures up to 250 degrees C. PMID:12479598

  2. Ultrasonic Behaviour of Liquid Crystalline Mixture of Octadecanol and Cholestrol

    NASA Astrophysics Data System (ADS)

    Kor, S. K.; Srivastava, A. K.

    1985-02-01

    The paper reports experimental results of ultrasonic absorption and velocity in a liquid crystalline mixture of ocatadecanol and cholestrol with different concentrations and its behaviour with temperature specially near transition temperature. The absorption has been measured using the pulse technique and the velocity with the help of an acoustic interferometer both at a single frequency of 2 MHz. The temperature has been controlled to within ± 0.2°C. Abrupt increase in absorption and decrease in velocity has been observed near cholesteric-isotropic transition temperature and the results have been discussed qualitatively.

  3. Improved ultrasonic standard reference blocks

    NASA Technical Reports Server (NTRS)

    Eitzen, D. G.

    1975-01-01

    A program to improve the quality, reproducibility and reliability of nondestructive testing through the development of improved ASTM-type ultrasonic reference standards is described. Reference blocks of aluminum, steel, and titanium alloys were considered. Equipment representing the state-of-the-art in laboratory and field ultrasonic equipment was obtained and evaluated. Some RF and spectral data on ten sets of ultrasonic reference blocks were taken as part of a task to quantify the variability in response from nominally identical blocks. Techniques for residual stress, preferred orientation, and microstructural measurements were refined and are applied to a reference block rejected by the manufacturer during fabrication in order to evaluate the effect of metallurgical condition on block response.

  4. Ultrasonic ash/pyrite liberation

    SciTech Connect

    Yungman, B.A.; Buban, K.S.; Stotts, W.F.

    1990-06-01

    The objective of this project was to develop a coal preparation concept which employed ultrasonics to precondition coal prior to conventional or advanced physical beneficiation processes such that ash and pyrite separation were enhanced with improved combustible recovery. Research activities involved a series of experiments that subjected three different test coals, Illinois No. 6, Pittsburgh No. 8, and Upper Freeport, ground to three different size fractions (28 mesh [times] 0, 200 mesh [times] 0, and 325 mesh [times] 0), to a fixed (20 kHz) frequency ultrasonic signal prior to processing by conventional and microbubble flotation. The samples were also processed by conventional and microbubble flotation without ultrasonic pretreatment to establish baseline conditions. Product ash, sulfur and combustible recovery data were determined for both beneficiation processes.

  5. Improved ultrasonic standard reference blocks

    NASA Technical Reports Server (NTRS)

    Eitzen, D. G.; Sushinsky, G. F.; Chwirut, D. J.; Bechtoldt, C. J.; Ruff, A. W.

    1976-01-01

    A program to improve the quality, reproducibility and reliability of nondestructive testing through the development of improved ASTM-type ultrasonic reference standards is described. Reference blocks of aluminum, steel, and titanium alloys are to be considered. Equipment representing the state-of-the-art in laboratory and field ultrasonic equipment was obtained and evaluated. RF and spectral data on ten sets of ultrasonic reference blocks have been taken as part of a task to quantify the variability in response from nominally identical blocks. Techniques for residual stress, preferred orientation, and micro-structural measurements were refined and are applied to a reference block rejected by the manufacturer during fabrication in order to evaluate the effect of metallurgical condition on block response. New fabrication techniques for reference blocks are discussed and ASTM activities are summarized.

  6. Flexible ultrasonic pipe inspection apparatus

    DOEpatents

    Jenkins, Charles F. (Aiken, SC); Howard, Boyd D. (Augusta, GA)

    1998-01-01

    A flexible, modular ultrasonic pipe inspection apparatus, comprising a flexible, hollow shaft that carries a plurality of modules, including at least one rotatable ultrasonic transducer, a motor/gear unit, and a position/signal encoder. The modules are connected by flexible knuckle joints that allow each module of the apparatus to change its relative orientation with respect to a neighboring module, while the shaft protects electrical wiring from kinking or buckling while the apparatus moves around a tight corner. The apparatus is moved through a pipe by any suitable means, including a tether or drawstring attached to the nose or tail, differential hydraulic pressure, or a pipe pig. The rotational speed of the ultrasonic transducer and the forward velocity of the apparatus are coordinated so that the beam sweeps out the entire interior surface of the pipe, enabling the operator to accurately assess the condition of the pipe wall and determine whether or not leak-prone corrosion damage is present.

  7. Lecture 4: transmission lines and capacitors

    SciTech Connect

    Butcher, R.R.

    1980-01-01

    The topic of this lecture is pulse forming networks. The first item of discussion will be transmission lines because they are so prevalent, even if only in the form of coaxial cable. From there the subject will proceed to pulse-forming networks: the practical problems encountered with them, their advantages, and disadvantages. Capacitors will be our final topic, as they are the limiting factor in lumped transmission elements.

  8. PLATE WAVE RESONANCE WITH AIR-COUPLED ULTRASONICS

    SciTech Connect

    Bar, H. N. [National Metallurgical Laboratory, Jamshedpur, India 831007 (India); Dayal, V.; Barnard, D.; Hsu, D. K. [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011 (United States)

    2010-02-22

    Air-coupled ultrasonic transducers can excite plate waves in metals and composites. The coincidence effect, i.e., the wave vector of plate wave coincides with projection of exciting airborne sound vector, leads to a resonance which strongly amplifies the sound transmission through the plate. The resonance depends on the angle of incidence and the frequency. In the present study, the incidence angle for maximum transmission (theta{sub max}) is measured in plates of steel, aluminum, carbon fiber reinforced composites and honeycomb sandwich panels. The variations of (theta{sub max}) with plate thickness are compared with theoretical values in steel, aluminum and quasi-isotropic carbon fiber composites. The enhanced transmission of air-coupled ultrasound at oblique incidence can substantially improve the probability of flaw detection in plates and especially in honeycomb structures. Experimental air-coupled ultrasonic scan of subtle flaws in CFRP laminates showed definite improvement of signal-to-noise ratio with oblique incidence at theta{sub max}.

  9. Efficient imaging techniques using an ultrasonic array

    NASA Astrophysics Data System (ADS)

    Moreau, L.; Hunter, A. J.; Drinkwater, B. W.; Wilcox, P. D.

    2010-03-01

    Over the past few years, ultrasonic phased arrays have shown good potential for non-destructive testing (NDT), thanks to high resolution imaging algorithms that allow the characterization of defects in a structure. Many algorithms are based on the full matrix capture, obtained by firing each element of an ultrasonic array independently, while collecting the data with all elements. Because of the finite sound velocity in the specimen, two consecutive firings must be separated by a minimum time interval. Therefore, more elements in the array require longer data acquisition times. Moreover, if the array has N elements, then the full matrix contains N2 temporal signals to be processed. Because of the limited calculation speed of current computers, a large matrix of data can result in rather long post-processing times. In an industrial context where real-time imaging is desirable, it is crucial to reduce acquisition and/or post-processing times. This paper investigates methods designed to reduce acquisition and post-processing times for the TFM and wavenumber algorithms. To reduce data capture and post-processing, limited transmission cycles are used. Post-processing times is also further reduced by demodulating the data to baseband, which allows reducing the sampling rate of signals. Results are presented so that a compromise can be made between acquisition time, post-processing time and image quality. Possible improvement of images quality, using the effective aperture theory, is discussed. This has been implemented for the TFM but it still has to be developed for the wavenumber algorithm.

  10. Ultrasonic Thermometry for In-Pile Temperature Detection

    SciTech Connect

    J.E. Daw; J.L. Rempe; S.C. Wilkins

    2002-11-01

    The Idaho National Laboratory has recently initiated a new effort to evaluate the viability of using ultrasonic thermometry technology as an improved sensor for detecting temperature during irradiation testing. Ultrasonic thermometers (UTs) work on the principle that the speed at which sound travels through a material (acoustic velocity) is dependant on the temperature of the material. By introducing an acoustic pulse to the sensor and measuring the time delay of echoes, temperature may be derived. UTs have several advantages over other sensor types. UTs can be made very small, as the sensor consists only of a small diameter rod which may or may not require a sheath. Measurements may be made near the melting point of the sensor material, as no electrical insulation is required; and shunting effects are avoided. Most attractive, however, is the ability to introduce acoustic discontinuities to the sensor, as this enables temperature measurements at several points along the sensor length (allowing temperature profiling with a single sensor). A typical multi-sensor UT system, with key components identified, is shown in Figure 1. As indicated in this figure, a narrow ultrasonic pulse is generated in a magnetostrictive rod by an excitation coil. The ultrasonic pulse propagates to the sensor wire, where a fraction of the pulse energy is reflected at each discontinuity (notches or diameter change). Each reflected pulse is received by the excitation coil, transformed into an electrical signal, amplified and evaluated in a start/stop counter system. The time interval between two adjacent echoes is evaluated and compared to a calibration curve to give the average temperature in the corresponding sensor segment. When a number of notches are available on the wire sensor, the various measurements give access to a temperature profile along the probe. UTs have been used successfully for several applications; however, several problems have limited the success of these sensors. For example, signal processing can be very complicated, as multiple echoes may overlap. Contact between the sensor and solid materials can cause extraneous echoes. If a sheath is required, contact bonding at high temperatures may cause extraneous echoes or attenuation of primary echoes. The most successful materials used in previous studies, tungsten and rhenium, are unattractive for nuclear applications due to material transmutation. Clearly, in order for ultrasonic thermometers to be viable for an in-pile sensor, these issues must be resolved through the use of modern signal processing and materials technologies. As part of the INL feasibility study, all of the issues associated with UT use and proposed resolution options will be identified and evaluated. Once most promising options are proven, it is planned to produce one or more prototype ultrasonic temperature sensors for evaluation. Ultimately, a full test should include a long term installation in a high temperature test assembly installed in a high neutron flux environment, such as that found in the Idaho National Laboratory’s Advanced Test Reactor.

  11. Concurrent ultrasonic weld evaluation system

    DOEpatents

    Hood, D.W.; Johnson, J.A.; Smartt, H.B.

    1985-09-04

    A system for concurrent, non-destructive evaluation of partially completed welds for use in conjunction with an automated welder. The system utilizes real time, automated ultrasonic inspection of a welding operation as the welds are being made by providing a transducer which follows a short distance behind the welding head. Reflected ultrasonic signals are analyzed utilizing computer based digital pattern recognition techniques to discriminate between good and flawed welds on a pass by pass basis. The system also distinguishes between types of weld flaws.

  12. Ultrasonic Attenuation in Lanthanum Monochalcogenides

    NASA Astrophysics Data System (ADS)

    Yadav, Raja; Singh, Devraj

    2001-06-01

    Ultrasonic attenuation due to phonon-phonon interaction and thermoelastic relaxation are studied in Lanthanum Monochalcogenides in <110> direction at different higher temperatures. For evaluation of ultrasonic absorption coefficients the second and third order elastic constants (SOEC) and (TOEC) are also calculated. Shear wave attenuation shows maximum along <110> propagation direction with polarized along <110> and the attenuation increases at higher temperatures. Thermo-elastic loss is very small compared to phonon-viscosity loss. Behavior of temperature dependence of the absorption is the same as in case of pure metals and dielectric crystals.

  13. Concurrent ultrasonic weld evaluation system

    DOEpatents

    Hood, Donald W. (Idaho Falls, ID); Johnson, John A. (Idaho Falls, ID); Smartt, Herschel B. (Idaho Falls, ID)

    1987-01-01

    A system for concurrent, non-destructive evaluation of partially completed welds for use in conjunction with an automated welder. The system utilizes real time, automated ultrasonic inspection of a welding operation as the welds are being made by providing a transducer which follows a short distance behind the welding head. Reflected ultrasonic signals are analyzed utilizing computer based digital pattern recognition techniques to discriminate between good and flawed welds on a pass by pass basis. The system also distinguishes between types of weld flaws.

  14. Accuracy of fetal pulse oximetry and pitfalls in measurements

    Microsoft Academic Search

    Roel Nijland; Henk W Jongsma; Jan G. Nijhuis; Berend Oeseburg

    1997-01-01

    Pulse oximetry is a technique for estimating arterial oxygen saturation continuously and non-invasively. Reflectance pulse oximetry might become useful for monitoring the fetus during labour but it is much more susceptible to all kinds of physiological variations than the well-established transmission pulse oximetry for neonatal or adult monitoring. This review focuses on the accuracy of reflectance pulse oximetry. Results of

  15. Pulsed stress behavior of flexible thick film resistors

    Microsoft Academic Search

    D. Bonfertl; H. Wolfl; H. Gieser; G. Klink; K. Bock; P. Svasta; C. Ionescu

    2008-01-01

    In order to investigate the behavior for very high current densities on polymer resistors on flexible substrates, a pulsed measurement technique was applied. The analytical test technique of transmission line pulsing (TLP) allows, on the basis of square pulses, the in-situ monitoring of the voltages and currents at the device under test (DUT) during pulsing and helps to gain fundamental

  16. Pulsed stress behavior of flexible thick film resistors

    Microsoft Academic Search

    D. Bonfert; H. Wolf; H. Gieser; G. Klink; K. Bock; P. Svasta; C. Ionescu

    2008-01-01

    In order to investigate the behavior for very high current densities of polymer resistors on flexible substrates, a pulsed measurement technique was applied. The analytical test technique of Transmission Line Pulsing (TLP) allows, on the basis of square pulses, the in-situ monitoring of the voltages and currents at the Device Under Test (DUT) during pulsing and helps to gain fundamental

  17. Imaging Laser Ultrasonics Measurement of the Elastodynamic Properties of Paper

    SciTech Connect

    Telschow, Kenneth Louis; Deason, Vance Albert

    2001-10-01

    Many sheet and plate material industries (e.g. paper) desire knowledge of the anisotropic stiffness properties of their material to optimize the manufacturing process. A determination of the anisotropic elastic matrix would be very beneficial for determination of parameters, such as as microstructural texture, fiber or grain orientation and stiffness. The propagation of ultrasonic waves in plates is a method for determining the anisotropic elastic properties in a nondestructive manner. Laser ultrasonics offes a noncontacting means to implement these measurements in the workplace by employing pulsed or modulated light to excite symmetric and antisymmetric plate waves concurrent with optical interferometric detection. Measurements can then be performed along the machine and cross directions to obtain parameters that are used empirically for process monitoring. Recently, the INEEL has developed a full-field view laser based ultrasonic imaging method that allows simultaneous measurement of plate wave motion in all planar directions within a single image without scanning. The imaging measurements are based on dynamic holography using photorefractive materials for interferometric deteciton and are operated as normal video rates. Results from this laser based imaging approach are presented that record Lamb wave mode wavefronts in all planar directions from localized sources in a single image. Specific numerical predictions for flexural wave propagation in distinctly different types of paper accounting fully for orthotropic anisotropy are presented and compared with direct imaging measurements. Very good agreement with theoretical calculations is obtained for the lowest antisymmetric plate mode in all planar directions using paper properties independently determined by others.

  18. The Application of Ultrasonic Inspection to Crimped Electrical Connections

    NASA Technical Reports Server (NTRS)

    Cramer, K. Elliott; Perey, Daniel F.; Yost, William T.

    2010-01-01

    The development of a new ultrasonic measurement technique to quantitatively assess wire crimp terminations is discussed. The development of a prototype instrument, based on a modified, commercially available, crimp tool, is demonstrated for applying this technique when wire crimps are installed. The crimp tool has three separate crimping locations that accommodate the three different ferrule diameters. The crimp tool in this study is capable of crimping wire diameters ranging from 12 to 26 American Wire Gauge (AWG). A transducer design is presented that allows for interrogation of each of the three crimp locations on the crimp tool without reconfiguring the device. An analysis methodology, based on transmitted ultrasonic energy and timing of the first received pulse is shown to correlate to both crimp location in the tool and the AWG of the crimp/ferrule combination. The detectability of a number of the crimp failure pathologies, such as missing strands, partially inserted wires and incomplete crimp compression, is discussed. A wave propagation model, solved by finite element analysis, describes the compressional ultrasonic wave propagation through the junction during the crimping process.

  19. Noise reduction in ultrasonic NDT using undecimated wavelet transforms.

    PubMed

    Pardo, E; San Emeterio, J L; Rodriguez, M A; Ramos, A

    2006-12-22

    Translation-invariant wavelet processing is applied to grain noise reduction in ultrasonic non-destructive testing of materials. In particular, the undecimated wavelet transform (UWT), which is essentially a discrete wavelet transform (DWT) that avoids decimation, is used. Two different UWT processors have been specifically developed for that purpose, based on two UWT implementation schemes: the "à trous" algorithm and the cycle-spinning scheme. The performance of these two UWT processors is compared with that of a classical DWT processor, by using synthetic grain noise registers and experimental pulse-echo NDT traces. The synthetic ultrasonic traces have been generated by an own-developed frequency-domain model that includes frequency dependence in both material attenuation and scattering. The experimental ultrasonic traces have been obtained by inspecting a piece of carbon-fiber reinforced plastic composite in which we have mechanized artificial flaws. Decomposition level-dependent thresholds, which are suitable for correlated noise, are specifically determined in all cases. Soft thresholding, Daubechies db6 mother wavelet and the three well-known threshold selection rules, Universal, Minimax and SURE, are applied to the different decomposition levels. The performance of the different de-noising procedures for single echo detection has been comparatively evaluated in terms of signal-to-noise ratio enhancement. PMID:16797651

  20. Dental hard tissue characterization using laser-based ultrasonics

    NASA Astrophysics Data System (ADS)

    Blodgett, David W.; Massey, Ward L.

    2003-07-01

    Dental health care and research workers require a means of imaging the structures within teeth in vivo. One critical need is the detection of tooth decay in its early stages. If decay can be detected early enough, the process can be monitored and interventional procedures, such as fluoride washes and controlled diet, can be initiated to help re-mineralize the tooth. Currently employed x-ray imaging is limited in its ability to visualize interfaces and incapable of detecting decay at a stage early enough to avoid invasive cavity preparation followed by a restoration. To this end, non-destructive and non-contact in vitro measurements on extracted human molars using laser-based ultrasonics are presented. Broadband ultrasonic waves are excited in the extracted sections by using a pulsed carbon-dioxide (CO2) laser operating in a region of high optical absorption in the dental hard tissues. Optical interferometric detection of the ultrasonic wave surface displacements in accomplished with a path-stabilized Michelson-type interferometer. Results for bulk and surface in-vitro characterization of caries are presented on extracted molars with pre-existing caries.

  1. Retardation and reduction of pulse distortion by group-velocity dispersion through pulse shaping

    NASA Astrophysics Data System (ADS)

    Eliyahu, Danny; Salvatore, Randal A.; Rosen, Joseph; Yariv, Amnon; Drolet, Jean-Jacques

    1995-06-01

    We show that a reduction in the pulse distortion caused by chromatic dispersion can be achieved through pulse shaping. We argue that a simple binary phase mask in the Fourier plane of the laser spectrum can improve the transmission of short pulses in a dispersive channel through reduced broadening. The argument was tested experimentally, and a good agreement was found with the theory.

  2. Acousto-ultrasonic nondestructive evaluation of materials using laser beam generation and detection. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Huber, Robert D.; Green, Robert E., Jr.

    1990-01-01

    The acousto-ultrasonic method has proven to be a most interesting technique for nondestructive evaluation of the mechanical properties of a variety of materials. Use of the technique or a modification thereof, has led to correlation of the associated stress wave factor with mechanical properties of both metals and composite materials. The method is applied to the nondestructive evaluation of selected fiber reinforced structural composites. For the first time, conventional piezoelectric transducers were replaced with laser beam ultrasonic generators and detectors. This modification permitted true non-contact acousto-ultrasonic measurements to be made, which yielded new information about the basic mechanisms involved as well as proved the feasibility of making such non-contact measurements on terrestrial and space structures and heat engine components. A state-of-the-art laser based acousto-ultrasonic system, incorporating a compact pulsed laser and a fiber-optic heterodyne interferometer, was delivered to the NASA Lewis Research Center.

  3. High-Performance Scanning Acousto-Ultrasonic System

    NASA Technical Reports Server (NTRS)

    Roth, Don; Martin, Richard; Kautz, Harold; Cosgriff, Laura; Gyekenyesi, Andrew

    2006-01-01

    A high-performance scanning acousto-ultrasonic system, now undergoing development, is designed to afford enhanced capabilities for imaging microstructural features, including flaws, inside plate specimens of materials. The system is expected to be especially helpful in analyzing defects that contribute to failures in polymer- and ceramic-matrix composite materials, which are difficult to characterize by conventional scanning ultrasonic techniques and other conventional nondestructive testing techniques. Selected aspects of the acousto-ultrasonic method have been described in several NASA Tech Briefs articles in recent years. Summarizing briefly: The acousto-ultrasonic method involves the use of an apparatus like the one depicted in the figure (or an apparatus of similar functionality). Pulses are excited at one location on a surface of a plate specimen by use of a broadband transmitting ultrasonic transducer. The stress waves associated with these pulses propagate along the specimen to a receiving transducer at a different location on the same surface. Along the way, the stress waves interact with the microstructure and flaws present between the transducers. The received signal is analyzed to evaluate the microstructure and flaws. The specific variant of the acousto-ultrasonic method implemented in the present developmental system goes beyond the basic principle described above to include the following major additional features: Computer-controlled motorized translation stages are used to automatically position the transducers at specified locations. Scanning is performed in the sense that the measurement, data-acquisition, and data-analysis processes are repeated at different specified transducer locations in an array that spans the specimen surface (or a specified portion of the surface). A pneumatic actuator with a load cell is used to apply a controlled contact force. In analyzing the measurement data for each pair of transducer locations in the scan, the total (multimode) acousto-ultrasonic response of the specimen is utilized. The analysis is performed by custom software that extracts parameters of signals in the time and frequency domains. The computer hardware and software provide both real-time and postscan processing and display options. For example, oscilloscope displays of waveforms and power spectral densities are available in real time. Images can be computed while scanning continues. Signals can be digitally preprocessed and/or post-processed by filtering, windowing, time-segmenting, and running-waveform-averaging algorithms. In addition, the software affords options for off-line simulation of the waveform-data-acquisition and scanning processes. In tests, the system has been shown to be capable of characterizing microstructural changes and defects in SiC/SiC and C/SiC ceramic-matrix composites. Delaminations, variations in density, microstructural changes attributable to infiltration by silicon, and crack-space indications (defined in the next sentence) have been revealed in images formed from several time- and frequency-domain parameters of scanning acousto-ultrasonic signals. The crack-space indications were image features that were not revealed by other nondestructive testing methods and are so named because they turned out to mark locations where cracking eventually occurred.

  4. HIV Transmission

    PubMed Central

    Shaw, George M.; Hunter, Eric

    2012-01-01

    HIV-1 is transmitted by sexual contact across mucosal surfaces, by maternal-infant exposure, and by percutaneous inoculation. For reasons that are still incompletely understood, CCR5-tropic viruses (R5 viruses) are preferentially transmitted by all routes. Transmission is followed by an orderly appearance of viral and host markers of infection in the blood plasma. In the acute phase of infection, HIV-1 replicates exponentially and diversifies randomly, allowing for an unambiguous molecular identification of transmitted/founder virus genomes and a precise characterization of the population bottleneck to virus transmission. Sexual transmission of HIV-1 most often results in productive clinical infection arising from a single virus, highlighting the extreme bottleneck and inherent inefficiency in virus transmission. It remains to be determined if HIV-1 transmission is largely a stochastic process whereby any reasonably fit R5 virus can be transmitted or if there are features of transmitted/founder viruses that facilitate their transmission in a biologically meaningful way. Human tissue explant models of HIV-1 infection and animal models of SIV/SHIV/HIV-1 transmission, coupled with new challenge virus strains that more closely reflect transmitted/founder viruses, have the potential to elucidate fundamental mechanisms in HIV-1 transmission relevant to vaccine design and other prevention strategies. PMID:23043157

  5. Tunable ultrasonic phononic crystal controlled by infrared radiation

    NASA Astrophysics Data System (ADS)

    Walker, Ezekiel; Reyes, Delfino; Rojas, Miguel Mayorga; Krokhin, Arkadii; Wang, Zhiming; Neogi, Arup

    2014-10-01

    A tunable phononic crystal based ultrasonic filter was designed by stimulating the phase of the polymeric material embedded in a periodic structure using infrared radiation. The acoustic filter can be tuned remotely using thermal stimulation induced by the infrared radiation. The filter is composed of steel cylinder scatterers arranged periodically in a background of bulk poly (N-isopropylacrylamide) polymer hydrogel. The lattice structure creates forbidden bands for certain sets of mechanical waves that cause it to behave as an ultrasonic filter. Since the bandstructure is determined by not only the arrangement of the scatterers but also the physical properties of the materials composing the scatterers and background, modulating either the arrangement or physical properties will alter the effect of the crystal on propagating mechanical waves. Here, the physical properties of the filter are varied by inducing changes in the polymer hydrogel using an electromagnetic thermal stimulus. With particular focus on the k00-wave, the transmission of ultrasonic wave changes by as much as 20 dBm, and band widths by 22% for select bands.

  6. On-line ultrasonic characterisation of barium doped lanthanum perovskites

    NASA Astrophysics Data System (ADS)

    Thamilmaran, P.; Arunachalam, M.; Sankarrajan, S.; Sakthipandi, K.

    2015-06-01

    Perovskite manganite samples La1-xBaxMnO3 with the composition of x=0.30, 0.33 and 0.36 were prepared by employing solid state reaction technique. The X-ray diffraction (XRD) patterns confirmed the rhombhedral structure with R3c space group of the samples. The obtained energy dispersive analysis X-rays (EDX) spectra of the samples have confirmed the elemental composition of the samples. The scanning electron microscope (SEM) images of the samples were used to find out the size of the particles. In-situ ultrasonic measurements were carried out on the samples by through transmission method. The temperature dependence of the ultrasonic parameters revealed interesting features of the samples. The observed ultrasonic velocities and attenuation both in longitudinal and shear mode are related to the paramagnetic (PM) to ferromagnetic (FM) phase transition in the prepared samples. The results confirmed that an increase in the barium content in the sample leads to an increase in the phase transition temperature TC.

  7. Simulation of Low-Intensity Ultrasound Propagating in a Beagle Dog Dentoalveolar Structure to Investigate the Relations between Ultrasonic Parameters and Cementum Regeneration.

    PubMed

    Vafaeian, Behzad; Al-Daghreer, Saleh; El-Rich, Marwan; Adeeb, Samer; El-Bialy, Tarek

    2015-08-01

    The therapeutic effect of low-intensity pulsed ultrasound on orthodontically induced inflammatory root resorption is believed to be brought about through mechanical signals induced by the low-intensity pulsed ultrasound. However, the stimulatory mechanism triggering dental cell response has not been clearly identified yet. The aim of this study was to evaluate possible relations between the amounts of new cementum regeneration and ultrasonic parameters such as pressure amplitude and time-averaged energy density. We used the finite-element method to simulate the previously published experiment on ultrasonic wave propagation in the dentoalveolar structure of beagle dogs. Qualitative relations between the thickness of the regenerated cementum in the experiment and the ultrasonic parameters were observed. Our results indicated that the areas of the root surface with greater ultrasonic pressure were associated with larger amounts of cementum regeneration. However, the establishment of reliable quantitative correlations between ultrasound parameters and cementum regeneration requires more experimental data and simulations. PMID:25957755

  8. Hidden corrosion detection in aircraft aluminum structures using laser ultrasonics and wavelet transform signal analysis.

    PubMed

    Silva, M Z; Gouyon, R; Lepoutre, F

    2003-06-01

    Preliminary results of hidden corrosion detection in aircraft aluminum structures using a noncontact laser based ultrasonic technique are presented. A short laser pulse focused to a line spot is used as a broadband source of ultrasonic guided waves in an aluminum 2024 sample cut from an aircraft structure and prepared with artificially corroded circular areas on its back surface. The out of plane surface displacements produced by the propagating ultrasonic waves were detected with a heterodyne Mach-Zehnder interferometer. Time-frequency analysis of the signals using a continuous wavelet transform allowed the identification of the generated Lamb modes by comparison with the calculated dispersion curves. The presence of back surface corrosion was detected by noting the loss of the S(1) mode near its cutoff frequency. This method is applicable to fast scanning inspection techniques and it is particularly suited for early corrosion detection. PMID:12782263

  9. Phase-delayed laser diode array allows ultrasonic guided wave mode selection and tuning

    NASA Astrophysics Data System (ADS)

    Karppinen, Pasi; Salmi, Ari; Moilanen, Petro; Karppinen, Timo; Zhao, Zuomin; Myllylä, Risto; Timonen, Jussi; Hæggström, Edward

    2013-04-01

    Selecting and tuning modes are useful in ultrasonic guided wave non-destructive testing (NDT) since certain modes at various center frequencies are sensitive to specific types of defects. Ideally one should be able to select both the mode and the center frequency of the launched waves. We demonstrated that an affordable laser diode array can selectively launch either the S0 or A0 ultrasonic wave mode at a chosen center frequency into a polymer plate. A fiber-coupled diode array (4 elements) illuminated a 2 mm thick acrylic plate. A predetermined time delay matching the selected mode and frequency was employed between the output of the elements. The generated ultrasound was detected by a 215 kHz piezo receiver. Our results imply that this array permits non-contacting guided wave ultrasonic NDT. The solution is small, affordable, and robust in comparison to conventional pulsed lasers. In addition, it does not require experienced operators.

  10. Non-destructive evaluation of depth of surface cracks using ultrasonic frequency analysis.

    PubMed

    Her, Shiuh-Chuan; Lin, Sheng-Tung

    2014-01-01

    Ultrasonic is one of the most common uses of a non-destructive evaluation method for crack detection and characterization. The effectiveness of the acoustic-ultrasound Structural Health Monitoring (SHM) technique for the determination of the depth of the surface crack was presented. A method for ultrasonic sizing of surface cracks combined with the time domain and frequency spectrum was adopted. The ultrasonic frequency spectrum was obtained by Fourier transform technique. A series of test specimens with various depths of surface crack ranging from 1 mm to 8 mm was fabricated. The depth of the surface crack was evaluated using the pulse-echo technique. In this work, three different longitudinal waves with frequencies of 2.25 MHz, 5 MHz and 10 MHz were employed to investigate the effect of frequency on the sizing detection of surface cracks. Reasonable accuracies were achieved with measurement errors less than 7%. PMID:25225875

  11. A Portable Ultrasonic Nondestructive Inspection System for Metal Matrix Composite Track Shoes

    NASA Astrophysics Data System (ADS)

    Mi, Bao; Zhao, Xiaoliang; Qian, Tao; Stevenson, Mark; Kwan, Chiman; Owens, Steven E.; Royer, Roger L.; Tittmann, Bernhard R.; Raju, Basavaraju B.

    2007-03-01

    Cast aluminum track shoes reinforced with metal matrix composite (MMC) inserts at heavy loading areas such as center splines and sprocket windows are light in weight, and can resist high temperature and wear. Various defects such as disbonds at the insert-substrate interface, cracks and porosity in the MMC layer, etc. can be introduced during the manufacturing process and/or in service. This paper presents a portable ultrasonic system to automatically inspect tank track shoes for disbond. Ultrasonic pulse/echo inspection has shown good reliability for disbond detection. A prototype sensor array fixture has been designed and fabricated to prove the feasibility. Good agreements between the sensor fixture results and ultrasonic C-scan images were obtained.

  12. Evaluation of ultrasonics and optimized radiography for 2219-T87 aluminum weldments

    NASA Technical Reports Server (NTRS)

    Clotfelter, W. N.; Hoop, J. M.; Duren, P. C.

    1975-01-01

    Ultrasonic studies are described which are specifically directed toward the quantitative measurement of randomly located defects previously found in aluminum welds with radiography or with dye penetrants. Experimental radiographic studies were also made to optimize techniques for welds of the thickness range to be used in fabricating the External Tank of the Space Shuttle. Conventional and innovative ultrasonic techniques were applied to the flaw size measurement problem. Advantages and disadvantages of each method are discussed. Flaw size data obtained ultrasonically were compared to radiographic data and to real flaw sizes determined by destructive measurements. Considerable success was achieved with pulse echo techniques and with 'pitch and catch' techniques. The radiographic work described demonstrates that careful selection of film exposure parameters for a particular application must be made to obtain optimized flaw detectability. Thus, film exposure techniques can be improved even though radiography is an old weld inspection method.

  13. Ultrasonication-dependent production and breakdown lead to minimum-sized amyloid fibrils

    PubMed Central

    Chatani, Eri; Lee, Young-Ho; Yagi, Hisashi; Yoshimura, Yuichi; Naiki, Hironobu; Goto, Yuji

    2009-01-01

    Because of the insolubility and polymeric properties of amyloid fibrils, techniques used conventionally to analyze protein structure and dynamics have often been hampered. Ultrasonication can induce the monomeric solution of amyloidogenic proteins to form amyloid fibrils. However, ultrasonication can break down preformed fibrils into shorter fibrils. Here, combining these 2 opposing effects on ?2-microglobulin (?2-m), a protein responsible for dialysis-related amyloidosis, we present that ultrasonication pulses are useful for preparing monodispersed amyloid fibrils of minimal size with an average molecular weight of ?1,660,000 (140-mer). The production of minimal and monodispersed fibrils is achieved by the free energy minimum under competition between fibril production and breakdown. The small homogeneous fibrils will be of use for characterizing the structure and dynamics of amyloid fibrils, advancing molecular understanding of amyloidosis. PMID:19564620

  14. A Portable Ultrasonic Nondestructive Inspection System for Metal Matrix Composite Track Shoes

    SciTech Connect

    Mi Bao; Zhao Xiaoliang; Qian Tao; Stevenson, Mark; Kwan, Chiman [Intelligent Automation, Inc., 15400 Calhoun Dr., Suite 400, Rockville, MD 20855 (United States); Owens, Steven E.; Royer, Roger L. Jr. [FBS, Inc., 2134 Sandy Drive, Suite 14, State College, PA 16803 (United States); Tittmann, Bernhard R. [Dept of Engineering Science and Mechanics, Pennsylvania State University, PA 16802 (United States); Raju, Basavaraju B. [U.S. Army TACOM, 6501 E. 11 Mile Road, MS 255, Warren, MI 48397 (United States)

    2007-03-21

    Cast aluminum track shoes reinforced with metal matrix composite (MMC) inserts at heavy loading areas such as center splines and sprocket windows are light in weight, and can resist high temperature and wear. Various defects such as disbonds at the insert-substrate interface, cracks and porosity in the MMC layer, etc. can be introduced during the manufacturing process and/or in service. This paper presents a portable ultrasonic system to automatically inspect tank track shoes for disbond. Ultrasonic pulse/echo inspection has shown good reliability for disbond detection. A prototype sensor array fixture has been designed and fabricated to prove the feasibility. Good agreements between the sensor fixture results and ultrasonic C-scan images were obtained.

  15. Porosity detection in ceramic armor tiles via ultrasonic time-of-flight

    SciTech Connect

    Margetan, Frank J.; Richter, Nathaniel; Jensen, Terrence [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011 (United States)

    2011-06-23

    Some multilayer armor panels contain ceramic tiles as one constituent, and porosity in the tiles can affect armor performance. It is well known that porosity in ceramic materials leads to a decrease in ultrasonic velocity. We report on a feasibility study exploring the use of ultrasonic time-of-flight (TOF) to locate and characterize porous regions in armor tiles. The tiles in question typically have well-controlled thickness, thus simplifying the translation of TOF data into velocity data. By combining UT velocity measurements and X-ray absorption measurements on selected specimens, one can construct a calibration curve relating velocity to porosity. That relationship can then be used to translate typical ultrasonic C-scans of TOF-versus-position into C-scans of porosity-versus-position. This procedure is demonstrated for pulse/echo, focused-transducer inspections of silicon carbide (SiC) ceramic tiles.

  16. Ultrasonic micromixer for microfluidic systems

    Microsoft Academic Search

    Zhen Yang; Sohei Matsumoto; Hiroshi Goto; Mikio Matsumoto; Ryutaro Maeda

    2001-01-01

    This paper describes the design, fabrication and evaluation of an active micromixer for continuous flow. Mixing occurs directly from ultrasonic vibration. The intended use of the device is for integrated microchemical synthesis systems or for micro total analysis systems. The patterns of inlets, outlet and mixing chamber were formed in glass. The entire flow path was encapsulated by anodic bonding

  17. Automated Ultrasonic Pipe Weld Inspection

    Microsoft Academic Search

    Wolfram A. Karl; Peter SCHULTE; Michael JOSWIG; Rainer KATTWINKEL

    Summary This article contains an overview on automated ultrasonic w eld inspection for various pipe types. Some inspection steps might by carried out with portable t est equipment (e.g. pipe end test), but the weld inspection in all internationally relevant specif ications must be automated. The pipe geometry, the production process, and the further pipe usage determine if ND T

  18. Ultrasonic lithotripsy of bladder stones.

    PubMed

    Cetin, S; Ozgür, S; Yazicio?lu, A; Unsal, K; Ilker, Y

    1988-01-01

    In the second half of 1985, 15 patients with 25 bladder stones were treated with Lutzeyer's Ultrasonic Lithotriptor. Of the patients 13 underwent additional operations, mostly transurethral resection of the prostate. The average duration of lithotripsy was 30.5 minutes. Some difficulties were experienced especially when drilling hard stones and as a complication late urethral bleeding occurred in one patient. PMID:3170106

  19. Flexible ultrasonic pipe inspection apparatus

    DOEpatents

    Jenkins, C.F.; Howard, B.D.

    1994-01-01

    Pipe crawlers, pipe inspection {open_quotes}rabbits{close_quotes} and similar vehicles are widely used for inspecting the interior surfaces of piping systems, storage tanks and process vessels for damaged or flawed structural features. This paper describes the design of a flexible, modular ultrasonic pipe inspection apparatus.

  20. Ultrasonic Songs of Male Mice

    Microsoft Academic Search

    Timothy E Holy; Zhongsheng Guo

    2005-01-01

    Previously it was shown that male mice, when they encounter female mice or their pheromones, emit ultrasonic vocalizations with frequencies ranging over 30–110 kHz. Here, we show that these vocalizations have the characteristics of song, consisting of several different syllable types, whose temporal sequencing includes the utterance of repeated phrases. Individual males produce songs with characteristic syllabic and temporal structure.