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1

Air-coupled ultrasonic testing of metals using broadband pulses in through-transmission  

Microsoft Academic Search

A pair of air-coupled electrostatic ultrasonic transducers with polished metal backplates have been used to test metals using broadband pulses in non-contact through-transmission. A range of aluminium samples between 1.7mm and 12.9mm thick were successfully tested using entirely air-coupled non-contact bulk waves. Individual longitudinal reflections and mode-converted shear waves could be seen in the signals obtained through the thicker samples.

W. M. D. Wright; D. A. Hutchins

1999-01-01

2

Tunable time-reversal cavity for high-pressure ultrasonic pulses generation: A tradeoff between transmission and time compression  

NASA Astrophysics Data System (ADS)

This Letter presents a time reversal cavity that has both a high reverberation time and a good transmission factor. A multiple scattering medium has been embedded inside a fluid-filled reverberating cavity. This allows creating smart ultrasonic sources able to generate very high pressure pulses at the focus outside the cavity with large steering capabilities. Experiments demonstrate a 25 dB gain in pressure at the focus. This concept will enable us to convert conventional ultrasonic imaging probes driven by low power electronics into high power probes for therapeutic applications requiring high pressure focused pulses, such as histotripsy or lithotripsy.

Arnal, Bastien; Pernot, Mathieu; Fink, Mathias; Tanter, Mickael

2012-08-01

3

Pulsed ultrasonic stir welding system  

NASA Technical Reports Server (NTRS)

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.

Ding, R. Jeffrey (Inventor)

2013-01-01

4

Pulsed ultrasonic stir welding method  

NASA Technical Reports Server (NTRS)

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.

Ding, R. Jeffrey (Inventor)

2013-01-01

5

Ultrasonic flowmetering with reflected pulses  

E-print Network

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 ...

Hoyle, David C.

1984-01-01

6

A transmission oscillator ultrasonic spectrometer  

NASA Technical Reports Server (NTRS)

A continuous wave ultrasonic instrument capable of measuring very small changes in acoustic attenuation and phase velocity is described. This transmission oscillator ultrasonic spectrometer (TOUS) exhibits high sensitivity because it oscillates marginally. In spite of this high sensitivity, the TOUS system is relatively simple, compact, and inexpensive. These features suggest that the TOUS is suitable not only for precise laboratory measurements of the physical properties of materials, but also for field applications in nondestructive testing.

Conradi, M. S.; Miller, J. G.; Heyman, J. S.

1974-01-01

7

Ultrasonic-Transmission Testing Device  

NASA Technical Reports Server (NTRS)

Ultrasonic-testing apparatus measures transmission through component under inspection. Includes hand-held ultrasonic transmitter placed on one side of component and ultrasonic receiver placed on other side. However, no need to hold or manually align receiving transducer after initial setup. Transmitter loosely inserted in magnetic assembly on one side, while receiver placed in another magnetic assembly on other side. Magnetic coupling keeps transmitter and receiver assemblies pressed against component and keeps receiver alligned with transmitter as transmitter scans across surface of component. Receiver moved to locations otherwise inaccessible.

Atkins, Victor Ray; Bouvier, Carl

1996-01-01

8

Ultrasonic flowmetering with reflected pulses  

Microsoft Academic Search

Consolidated Edison of New York City has expressed the need for a new gasmeter for accurately monitoring large diameter interdistrict gas transmission lines for loss due to theft or leakage. A research effort aimed at developing a new flowmeter for Con Edison is described. The new flowmeter uses ultrasonic flowmetering technology in a novel way to meet Con Edison's four

D. C. Hoyle; L. R. Glicksman; C. R. Peterson

1984-01-01

9

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

Code of Federal Regulations, 2013 CFR

... false Ultrasonic pulsed echo imaging system. 892.1560...892.1560 Ultrasonic pulsed echo imaging system. (a) Identification. An ultrasonic pulsed echo imaging system is a device intended to project a pulsed sound beam into body...

2013-04-01

10

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

Code of Federal Regulations, 2012 CFR

... false Ultrasonic pulsed echo imaging system. 892.1560...892.1560 Ultrasonic pulsed echo imaging system. (a) Identification. An ultrasonic pulsed echo imaging system is a device intended to project a pulsed sound beam into body...

2012-04-01

11

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

Code of Federal Regulations, 2010 CFR

... false Ultrasonic pulsed echo imaging system. 892.1560...892.1560 Ultrasonic pulsed echo imaging system. (a) Identification. An ultrasonic pulsed echo imaging system is a device intended to project a pulsed sound beam into body...

2010-04-01

12

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

Code of Federal Regulations, 2014 CFR

... false Ultrasonic pulsed echo imaging system. 892.1560...892.1560 Ultrasonic pulsed echo imaging system. (a) Identification. An ultrasonic pulsed echo imaging system is a device intended to project a pulsed sound beam into body...

2014-04-01

13

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

Code of Federal Regulations, 2011 CFR

... false Ultrasonic pulsed echo imaging system. 892.1560...892.1560 Ultrasonic pulsed echo imaging system. (a) Identification. An ultrasonic pulsed echo imaging system is a device intended to project a pulsed sound beam into body...

2011-04-01

14

Lab Exercise Ultrasonic pulse-echo technique  

E-print Network

Lab Exercise Ultrasonic pulse-echo technique Sebastian Kr¨odel October 21, 2013 1 Ultrasonic Principle The propagation of ultrasonic waves (100kHz - 100MHz) in solid media is widely used for nondestructive testing. The wave velocity is the most common param- eter in these methods and describes

Daraio, Chiara

15

Ultrasonic thermometry using pulse techniques.  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

16

Through air transmission for ultrasonic nondestructive testing  

Microsoft Academic Search

The theoretical design and experimental evaluation of a prototype through air ultrasonic inspection system are described. It is based around a ceramic-epoxy composite transducer configuration that is tailored specifically for through transmission scanning in air. A simulation model is used for the design of transmission and reception devices and the main factors influencing transduction performance are discussed with respect to

D. Reilly; G. Hayward

1991-01-01

17

Effects of crack closure on ultrasonic transmission  

Microsoft Academic Search

Ultrasonic waves are attenuated as they propagate past the tip of a crack due to the reflection of the energy at the crack face and diffraction at the crack tip. Crack closure modifies the situation since partial transmission can occur at points along the crack face where asperities come in contact. This phenomenon is important in defining the ability to

R. B. Thompson; B. J. Skillings; L. W. Zachary; L. W. Schmerr; O. Buck

1983-01-01

18

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Code of Federal Regulations, 2012 CFR

...892.1550 Ultrasonic pulsed doppler imaging system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that...the features of continuous wave doppler-effect technology with...

2012-04-01

19

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Code of Federal Regulations, 2010 CFR

...892.1550 Ultrasonic pulsed doppler imaging system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that...the features of continuous wave doppler-effect technology with...

2010-04-01

20

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Code of Federal Regulations, 2014 CFR

...892.1550 Ultrasonic pulsed doppler imaging system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that...the features of continuous wave doppler-effect technology with...

2014-04-01

21

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Code of Federal Regulations, 2011 CFR

...892.1550 Ultrasonic pulsed doppler imaging system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that...the features of continuous wave doppler-effect technology with...

2011-04-01

22

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Code of Federal Regulations, 2013 CFR

...892.1550 Ultrasonic pulsed doppler imaging system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that...the features of continuous wave doppler-effect technology with...

2013-04-01

23

A pulsed ultrasonic distance measurement system based upon phase digitizing  

Microsoft Academic Search

A pulsed ultrasonic distance measurement system (UDMS) for use in air is described. A new method of timing is presented that is based upon the transmission of a binary-frequency shift-keyed (BFSK) signal followed by data acquisition and signal processing of phase-digitized information from the received signal. The method reduces many of the problems that arise when dealing with the nonideal

David Webster

1994-01-01

24

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

DOEpatents

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. 25 figures.

Thompson, D.O.; Hsu, D.K.

1993-12-14

25

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

DOEpatents

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.

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

1993-12-14

26

Ultrasonic unipolar pulse/echo instrument  

DOEpatents

An ultrasonic unipolar pulse/echo instrument uses active switches and a timing and drive circuitry to control electrical energy to a transducer, the discharging of the transducer, and the opening of an electrical pathway to the receiving circuitry for the returning echoes. The active switches utilize MOSFET devices along with decoupling circuitry to insure the preservation of the unipolar nature of the pulses, insure fast transition times, and maintain broad band width and time resolution. A housing contains the various circuitry and switches and allows connection to a power supply and a movable ultrasonic transducer. The circuitry maintains low impedance input to the transducer during transmitting cycles, and high impedance between the transducer and the receiving circuit during receive cycles to maintain the unipolar pulse shape. A unipolar pulse is valuable for nondestructive evaluation, a prime use for the present instrument.

Hughes, M.J.; Hsu, D.K.; Thompson, D.O.; Wormley, S.J.

1993-04-06

27

Ultrasonic unipolar pulse/echo instrument  

DOEpatents

An ultrasonic unipolar pulse/echo instrument uses active switches and a timing and drive circuitry to control electrical energy to a transducer, the discharging of the transducer, and the opening of an electrical pathway to the receiving circuitry for the returning echoes. The active switches utilize MOSFET devices along with decoupling circuitry to insure the preservation of the unipolar nature of the pulses, insure fast transition times, and maintain broad band width and time resolution. A housing contains the various circuitry and switches and allows connection to a power supply and a movable ultrasonic transducer. The circuitry maintains low impedance input to the transducer during transmitting cycles, and high impedance between the transducer and the receiving circuit during receive cycles to maintain the unipolar pulse shape. A unipolar pulse is valuable for nondestructive evaluation, a prime use for the present instrument.

Hughes, Michael S. (Ames, IA); Hsu, David K. (Ames, IA); Thompson, Donald O. (Ames, IA); Wormley, Samuel J. (Ames, IA)

1993-01-01

28

Pulse shaping with transmission lines  

DOEpatents

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.

Wilcox, R.B.

1985-08-15

29

Pulse shaping with transmission lines  

DOEpatents

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.

Wilcox, Russell B. (Oakland, CA)

1987-01-01

30

Coiled transmission line pulse generators  

DOEpatents

Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

McDonald, Kenneth Fox (Columbia, MO)

2010-11-09

31

Method of Pulse Transmission Measurements for Determining Sound Velocities  

Microsoft Academic Search

The purpose of this communication is lo describe an alternative arrangement for determining with pulse transmission methods, the propagational velocity of both P and S waves in rocks. The various methods in current use to determine velocities are reviewed by Simmons [1965] and Anderson and Liebermann [1966]. As noted by these authors, sophisticated and extremely precise techniques such as ultrasonic

Paul Mattaboni; Edward Schreiber

1967-01-01

32

Medical tomograph system using ultrasonic transmission  

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

33

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

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

34

Quantitative real-time pulsed Schlieren imaging of ultrasonic waves  

Microsoft Academic Search

A pulsed Schlieren system based on Raman-Nath scattering by ultrasonic waves in water is described. High powered, monochromatic infrared pulsed light is used in conjunction with axial optics and a video camera to visualize the acoustic field. Projection beam profiles in any plane parallel or orthogonal to the direction of acoustic propagation are demonstrated. Controlled delay between acoustic pulse and

A. Hanafy; C. I. Zanelli

1991-01-01

35

Fundamental Study of Smart IC Card System Using Ultrasonic Information Transmission  

Microsoft Academic Search

In this study, we propose a new type of smart IC card using ultrasonic information transmission. Ultrasonic transmission is safe for the human body and does not cause malfunctioning of electronic equipments. In addition, information transmission using ultrasonic can prevent ``skimming'' to utilize ultrasonic characteristics that have a large attenuation in air and a sharp directivity. Our study deals with

Shin-nosuke Suzuki; Manabu Ishihara; Tamotsu Katane; Osami Saito; Kazuto Kobayashi

2006-01-01

36

Capacitive micromachined ultrasonic transducer design for high power transmission  

Microsoft Academic Search

Capacitive micromachined ultrasonic transducers (cMUTs) were developed to meet the demands of the ultrasonic industry. To achieve maximum efficiency, the conventional operation of the cMUT requires a bias voltage close to the collapse voltage. Total acoustic output pressure is limited by the efficiency of the cMUT and the maximum-allowed pulse voltage on the membrane. In this paper, we propose the

Baris Bayram; Omer Oralkan; A. Sanli Ergun; E. Haeggstrom; G. G. Yaralioglu; B. T. Khuri-Yakub

2005-01-01

37

Probing of ultrasonic pulses by multidirectional K. Van Den Abeele" and 0. Leroy  

E-print Network

Probing of ultrasonic pulses by multidirectional light K. Van Den Abeele" and 0. Leroy K.U. Leuven multidirectional light diffraction by finite amplitude ultrasonic pulses is presented. When crossing the ultrasonic modulated in time. It is found that for special conditions, concerning direction of observation, ultrasonic

38

Using piezoelectric sensors for ultrasonic pulse velocity measurements in concrete  

NASA Astrophysics Data System (ADS)

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.

Kee, Seong-Hoon; Zhu, Jinying

2013-11-01

39

Correlation established between heat transfer and ultrasonic transmission properties of copper braze bonds  

NASA Technical Reports Server (NTRS)

Measuring and correlating the thermal conductivity and ultrasonic transmission of seven hot-brazed-bonded copper plates established a relationship between heat transfer and ultrasonic transmission properties of the bonds. This relationship permits the prediction of heat transfer characteristics from ultrasonic transmission tests.

Dinovi, R. A.

1967-01-01

40

Finite amplitude distortion-based inhomogeneous pulse echo ultrasonic imaging  

Microsoft Academic Search

Ultrasonic pulse echo imaging in inhomogeneous media suffers from significant lateral and contrast resolution losses due to the defocusing effects of the inhomogeneities. The losses in lateral and contrast resolution are associated with increases in the width of the mainbeam and increases in sidelobe levels, respectively. These two forms of resolution loss represent significant hurdles to improving the clinical utility

Ted Christopher

1997-01-01

41

Fuzzy Ultrasonic Testing System with Columnar Rod  

Microsoft Academic Search

This paper describes an ultrasonic testing system with a columnar rod. The general ultrasonic probe is affected by transmission pulse for measurement using the direct contact method. However, if we use a columnar rod between an ultrasonic probe and a target object, we can measure without the transmission pulse. This paper describes the measurement system of the object thickness by

J. Yasui; S. Kobashi; K. Kondo; Y. Hata

2006-01-01

42

Non-destructive characterization of CMP pads using scanning ultrasonic transmission  

Microsoft Academic Search

An automatic scanning ultrasonic transmission (UST) technique was developed and applied to nondestructive metrology and analysis of visco-elastic properties in full-size chemical mechanical planarization (CMP) pads prior to their use in CMP processing. The system is comprised of a specially designed ultrasonic transmitter as an emitter of acoustic vibrations and an ultrasonic probe as a receiver. Both, the transducer and

D. G. Totzke; A. Belyaev; W. Moreno; S. Ostapenko; I. Tarasov; W. Easter; A. Maury; A. Crevasse

2001-01-01

43

Coded pulse excitation for ultrasonic strain imaging.  

PubMed

Decorrelation strain noise can be significantly reduced in low echo-signal-to-noise (eSNR) conditions using coded excitation. Large time-bandwidth-product (>30) pulses are transmitted into tissue mimicking phantoms with 2.5-mm diameter inclusions that mimic the elastic properties of breast lesions. We observed a 5-10 dB improvement in eSNR that led to a doubling of the depth of focus for strain images with no reduction of spatial resolution. In high eSNR conditions, coded excitation permits the use of higher carrier frequencies and shorter correlation windows to improve the attainable spatial resolution for strain relative to that obtained with conventional short pulses. This paper summarizes comparative studies of strain imaging in noise-limited conditions obtained by short pulses and four common aperiodic codes (chirp, Barker, suboptimal, and Golay) as a function of attenuation, eSNR and applied strain. Imaging performance is quantified using SNR for displacement (SNRd), local modulation transfer function (LMTF), and contrast-to-noise ratio for strain (CNRepsilon). We found that chirp and Golay codes are the most robust for imaging soft tissue deformation using matched filter decoding. Their superior performance is obtained by balancing the need for low-range lobes, large eSNR improvement, and short-code duration. PMID:15801311

Liu, Jie; Insana, Michael F

2005-02-01

44

Coded Pulse Excitation for Ultrasonic Strain Imaging  

PubMed Central

Decorrelation strain noise can be significantly reduced in low echo-signal-to-noise (eSNR) conditions using coded excitation. Large time-bandwidth-product (>30) pulses are transmitted into tissue mimicking phantoms with 2.5-mm diameter inclusions that mimic the elastic properties of breast lesions. We observed a 5–10 dB improvement in eSNR that led to a doubling of the depth of focus for strain images with no reduction of spatial resolution. In high eSNR conditions, coded excitation permits the use of higher carrier frequencies and shorter correlation windows to improve the attainable spatial resolution for strain relative to that obtained with conventional short pulses. This paper summarizes comparative studies of strain imaging in noise-limited conditions obtained by short pulses and four common aperiodic codes (chirp, Barker, suboptimal, and Golay) as a function of attenuation, eSNR and applied strain. Imaging performance is quantified using SNR for displacement (SNRd), local modulation transfer function (LMTF), and contrast-to-noise ratio for strain (CNR?). We found that chirp and Golay codes are the most robust for imaging soft tissue deformation using matched filter decoding. Their superior performance is obtained by balancing the need for low-range lobes, large eSNR improvement, and short-code duration. PMID:15801311

Liu, Jie; Insana, Michael F.

2009-01-01

45

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

Microsoft Academic Search

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

Goeran VOGT; Carsten KOEHLER

2008-01-01

46

A Comparison of Q-Switched and Intensity Modulated Laser Pulses for Ultrasonic NDT  

Microsoft Academic Search

The purpose of this work was to investigate the potential of intensity modulated laser pulses for ultrasonic signal enhancement in NDT using a numerical model. Q-switched lasers produce broadband ultrasound which is susceptible to measurement noise. Intensity modulation can alleviate this problem by focussing the ultrasonic energy into a band centered around the modulation frequency. Ultrasonic waveforms and their DFTs

Terry Sanderson; Charles Ume; Jacek Jarzynski

1998-01-01

47

Near-Infrared Tomography by Detection of Ultrasonic Pulse Shift for Tissue Diagnosis  

NASA Astrophysics Data System (ADS)

An experimental apparatus for near-infrared absorption imaging by ultrasonic velocity shift using the 20 MHz ultrasonic transducer was fabricated for basic experiments of tissue characterization. The ultrasonic echo pulse shifts by thermal agitation by light was measured in the scattering medium as the ultrasonic transducer with 0.4mm beam width was translated above the sample. The optical information at the specified depth from the surface of the model tissue sample was obtained by our method.

Nishinaka, Fumihiko; Nakatani, Yumi; Wada, Kenji; Matsunaka, Toshiyuki; Horinaka, Hiromichi

48

Pulse transmission transceiver architecture for low power communications  

DOEpatents

Systems and methods for pulse-transmission low-power communication modes are disclosed. A method of pulse transmission communications includes: generating a modulated pulse signal waveform; transforming said modulated pulse signal waveform into at least one higher-order derivative waveform; and transmitting said at least one higher-order derivative waveform as an emitted pulse. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

Dress Jr., William B.; Smith, Stephen F.

2003-08-05

49

Ultrasonic pulse velocity test of concrete properties as specified in various standards  

Microsoft Academic Search

This is a review paper comparing critically eight standards. Methods for the determination of longitudinal pulse velocity and assessment of concrete properties by ultrasonic pulse velocity, as recommended by standards of the UK, USA, Germany, Russia, Slovakia, Hungary, and RILEM, are evaluated. It is shown that, despite the common basis of the measurement of ultrasonic longitudinal wave velocity, there are

S. Popovics; T. Nürnbergerová; B. Babál; J. S. Popovics

1996-01-01

50

Quantitative analysis of pulsed ultrasonic beam patterns using a schlieren system  

Microsoft Academic Search

The acoustic output from pulsed ultrasonic transducers has traditionally been analyzed with a hydrophone. Recently, a new faster technique has been developed using the principles of optical diffraction. This schlieren method allows the direct two-dimensional visualization of the ultrasonic beam as a pulse train. In order to obtain quantitative information in the form of temporal-average acoustic intensity, however, tomographic reconstruction

Byron Schneider; K. Kirk Shung

1996-01-01

51

Valuation of beachrock formation through ultrasonic pulse technique. A method to compare porosities in horizontal and vertical aspects  

NASA Astrophysics Data System (ADS)

The physical properties of carbonate sedimentary rocks provide important information about the precipitation conditions of cement material and furthermore contribute to studies that try to place the basic context of the phyisico-chemical and micro-environmental conditions of the time and location of rock formation. Porosity is an important factor of the evolution of precipitation, related to its rate, its origin - marine, meteoric, vadose etc -, the participation of the biological activity as well as the particular environmental and climatic conditions during precipitation. In this study, a fast, non-destructive method of ultrasonic pulse traveltimes determination has been applied to beachrock samples. The use of ultrasonic pulse transmission technique is widely used in order to estimate traveltimes of pulses through mainly structural materials. The aim of this study is to evaluate the results of velocity measurements both in vertical and horizontal directions on beachrock samples from Thassos Island, N. Greece. The relationship of ultrasonic pulses transmission velocities with the porosity of the formation has been widely developed in literature regarding sandstones as the most relative formation to beachrocks. The final results are also interpreted taking into account the physico-chemical properties of beachrocks, the topographic position of the formation and its sedimentary characteristics.

Psomiadis, D.; Vogiatzis, D.; Albanakis, K.; Christaras, V.; Dotsika, E.; Zisi, N.

2009-04-01

52

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

PubMed

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

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

2014-02-01

53

Photoacoustic generation of focused ultrasonic pulses with predefined temporal profiles including quasi-unipolar pressure pulses  

NASA Astrophysics Data System (ADS)

One of the applications of the photoacoustic effect in biomedical research is generation of ultra-short acoustic pressure pulses in tissue. An acoustic wave is generated directly in tissue or in an acoustically well coupled immersion liquid, thus avoiding mechanical resonances of the piezoelectric ultrasonic transducer. Although laser generation of the unipolar pressure pulses has been proposed and used before, little attention was paid to the change of the temporal shape of the pulse when it propagates from a transducer. Here we derive simple mathematical solution which helps to predict the pulse shape in the focal region of the transducer and to experimentally verify theoretical calculations showing generation of short quasi-unipolar pressure pulses.

Maslov, Konstantin; Zhang, Hao F.; Wang, Lihong V.

2008-02-01

54

Pulse transmission receiver with higher-order time derivative pulse correlator  

DOEpatents

Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission receiver includes: a higher-order time derivative pulse correlator; a demodulation decoder coupled to the higher-order time derivative pulse correlator; a clock coupled to the demodulation decoder; and a pseudorandom polynomial generator coupled to both the higher-order time derivative pulse correlator and the clock. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

Dress Jr., William B.; Smith, Stephen F.

2003-09-16

55

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

PubMed

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

Waag, Grunde; Hoff, Lars; Norli, Petter

2015-02-01

56

A comparison of Q-switched and intensity modulated laser pulses for ultrasonic NDT  

Microsoft Academic Search

The purpose of this work was to investigate the potential of intensity modulated laser pulses for ultrasonic signal enhancement\\u000a in NDT using a numerical model. Q-switched lasers produce broadband ultrasound which is susceptible to measurement noise.\\u000a Intensity modulation can alleviate this problem by focussing the ultrasonic energy into a band centered around the modulation\\u000a frequency. Ultrasonic waveforms and their DFTs

Terry Sanderson; Charles Ume; Jacek Jarzynski

1998-01-01

57

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

Microsoft Academic Search

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

Martin Pollakowski; Helmut Ermert

1994-01-01

58

An FPGA based multiple-output PWM pulse generator for ultrasonic cleaning machines  

Microsoft Academic Search

This paper presents design and implementation of a multiple-output 48 kHz PWM-controlled pulse generator for ultrasonic cleaning machines. The complete digital part including frequency and PWM-controlled pulse generator and display driver unit to drive four independent ultrasonic power units has been implemented on a single FPGA core. As a result, more precise (5Hz step) frequency adjustment and four independent but

Ali Tangel; Mehmet Yakut; Engin Afacan; Ulvi Güvenç; H. Sengul

2010-01-01

59

An Analysis of Pulsed Ultrasonic Fields as Measured by PVDF Spot-Poled Membrane Hydrophones  

Microsoft Academic Search

Absmcr-Transient fields of pulsed ultrasonic sources radiating into water were investigated experimentally. The measurements were made using dot and annular polyvinylidene fluoride (PVDF) spot-poled membrane hydrophones having element dimensions ranging from 0.3 mm to 1.0 mm. The transient ultrasonic fields were generated using thick piezoelectric circular plates and broadband thickness-resonant disks. Both source types produced pulses composed of the expected

GERALD R. HARRIS; EDWARD F. CAROME; HENRY D. DARDY

1983-01-01

60

Application of digital pulse shaping by least squares method to ultrasonic signals in composites  

NASA Technical Reports Server (NTRS)

For ultrasonic testing in composites, a signal processing tool is identified that can significantly enhance the sharpness of ultrasonic waveforms and provide clearer pictures of the nature of the material flaw. The technique artificially improves the resolution of the system to discrete events by pulse shaping the measured waveform based on the signal from a reference. The optimum pulse shape operator is determined from a least-squares method in the z-domain.

Kishoni, D.

1985-01-01

61

Pulse transmission transmitter including a higher order time derivate filter  

DOEpatents

Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission transmitter includes: a clock; a pseudorandom polynomial generator coupled to the clock, the pseudorandom polynomial generator having a polynomial load input; an exclusive-OR gate coupled to the pseudorandom polynomial generator, the exclusive-OR gate having a serial data input; a programmable delay circuit coupled to both the clock and the exclusive-OR gate; a pulse generator coupled to the programmable delay circuit; and a higher order time derivative filter coupled to the pulse generator. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

Dress Jr., William B.; Smith, Stephen F.

2003-09-23

62

Detection of cystic structures using pulsed ultrasonically induced resonant cavitation  

NASA Technical Reports Server (NTRS)

Apparatus and method for early detection of cystic structures indicative of ovarian and breast cancers uses ultrasonic wave energy at a unique resonance frequency for inducing cavitation in cystic fluid characteristic of cystic structures in the ovaries associated with ovarian cancer, and in cystic structures in the breast associated with breast cancer. Induced cavitation bubbles in the cystic fluid implode, creating implosion waves which are detected by ultrasonic receiving transducers attached to the abdomen of the patient. Triangulation of the ultrasonic receiving transducers enables the received signals to be processed and analyzed to identify the location and structure of the cyst.

Bar-Cohen, Yoseph (Inventor); Kovach, John S. (Inventor)

2002-01-01

63

Method of estimating tissue attenuation using wideband ultrasonic pulse and apparatus for use therein  

SciTech Connect

This patent describes a method of estimating tissue attenuation of ultrasound energy comprising the steps of: transmitting a wide band ultrasonic pulse into the tissue, the pulse having a frequency spectrum with a center frequency, detecting the pulse as reflected by the tissue, estimating decay of a measure of amplitude of the reflected pulse between two levels in the tissue to approximate the slope of the decay, estimating center frequency of the reflected pulse between the two levels, and obtaining tissue attenuation from the approximated slope of a measure of amplitude and the center frequency.

Flax, S.W.

1986-11-11

64

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

NASA Astrophysics Data System (ADS)

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.

Hou, Huirang; Zheng, Dandan; Nie, Laixiao

2015-04-01

65

Design and Development of Highly Efficient Transducer for Ultrasonic Wireless Power Transmission System  

NASA Astrophysics Data System (ADS)

In this paper, the transducer that is suitable for the ultrasonic wireless power transmission system is discussed. The transducer is designed based on the Mason's equivalent circuit theory, basically. Design parameters of the transducer are optimized for by using the multi physics analysis and developed. As results, it is confirmed that the transmission efficiency is drastically improved to more than 50%. This result suggests that the WPT by acoustic wave is practicable.

Hori, Yuki; Fujimori, Kazuhiro; Tsuruta, Kenji; Nogi, Shigeji

66

Pulse transmission receiver with higher-order time derivative pulse generator  

DOEpatents

Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission receiver includes: a front-end amplification/processing circuit; a synchronization circuit coupled to the front-end amplification/processing circuit; a clock coupled to the synchronization circuit; a trigger signal generator coupled to the clock; and at least one higher-order time derivative pulse generator coupled to the trigger signal generator. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

Dress Jr., William B.; Smith, Stephen F.

2003-08-12

67

Frequency tracked gated pulse technique for ultrasonic frequency  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

68

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

PubMed

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

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

2013-07-01

69

Application of ultrasonic-pulse-spectroscopy measurements to experimental stress analysis  

Microsoft Academic Search

We apply the technique of ultrasonic pulse spectroscopy to measure the interference effects between two shear waves propagating in specimens loaded in uniaxial compression. We show that the power spectrum of an echo containing both fast and slow components of a shear wave will exhibit periodic minima. The periodicity exhibited in the spectrum is 1\\/, where is the difference in

J. Blinka; W. Sachse

1976-01-01

70

A software controlled pulse compression technique applied to ultrasonic non?destructive testing  

Microsoft Academic Search

The pulse compression technique, which is widely used in Radar systems, has been successfully used in ultrasonic nondestructive testing (NDT) by hardware methods for real time display of the testing result to improve the signal?to?noise ratio (SNR). This technique transmits a linear frequency modulated signal and compresses the received signal by time delay of a linear frequency function. Therefore, the

2003-01-01

71

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

Microsoft Academic Search

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

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

2007-01-01

72

Precision pulse-timing instrumentation for ultrasonic nondestructive testing  

SciTech Connect

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.

Duncan, M.G.

1990-08-31

73

Development of Polygonal Buffer Rods for Ultrasonic Pulse-Echo Measurements  

NASA Astrophysics Data System (ADS)

In ultrasonic pulse-echo measurement with a long buffer rod (waveguide), it is required to prevent the generation of spurious echoes (often called trailing echoes) accompanying with a main echo in the buffer rod. In this work, new method to prevent such trailing echoes in the rod is proposed and the effectiveness of the method has been demonstrated experimentally and numerically. In the method the cross-sectional shape of the rod perpendicular to the axial direction is a polygon having sides any one of which is not parallel to any of the other sides, so that trailing echoes are hardly generated during the propagation of pulsed ultrasonic wave in the rod. Three-dimensional numerical simulations based on a finite different method are performed to examine the behaviours of ultrasonic pulse-echoes including trailing echoes for several types of buffer rods having different cross-sectional shapes such as a circle, triangle, square, pentagon, hexagon and heptagon. Based on the results, experiments with several buffer rods are carried out at frequency 5 MHz. It has been found that heptagon may be the suitable shape for effectively eliminating trailing echoes and improving the signal-to-noise ratio of the measured pulse-echo.

Foudzi, F. M.; Ihara, I.

2014-06-01

74

Video Transmission over Telephone Cable Pairs by Pulse Code Modulation  

Microsoft Academic Search

An experimental seven digit pulse code modulation (PCM) system has been built for the transmission of monochrome and color television signals over seven pairs of 22-gauge exchange area telephone cable, installed in the laboratory. A beam coding tube converts the signal to seven parallel digits of a binary Gray code at a 10 mc rate. All circuits except the coding

R. L. CARBREYt

1960-01-01

75

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

NASA Technical Reports Server (NTRS)

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%.

Sachse, W.; Ruoff, A. L.

1974-01-01

76

Quasisubharmonic vibrations in metal plates excited by high-power ultrasonic pulses  

Microsoft Academic Search

Strongly nonlinear vibration phenomena in metal plates excited by high-power ultrasonic pulses in different conditions are studied experimentally and theoretically. The experimental conditions for generating quasisubharmonics and subharmonics are found and discussed. The plate vibrations are characterized by waveforms, frequency spectra, pseudostate portraits, and Poincaré maps. Then, a three-degree-of-freedom vibroimpact-dynamic model is presented to explore the generation mechanisms of the

Zhao-Jiang Chen; Shu-Yi Zhang; Kai Zheng; Pao-Kuang Kuo

2009-01-01

77

Method and apparatus for characterizing reflected ultrasonic pulses  

NASA Technical Reports Server (NTRS)

The invention is a method of and apparatus for characterizing the amplitudes of a sequence of reflected pulses R1, R2, and R3 by converting them into corresponding electric signals E1, E2, and E3 to substantially the same value during each sequence thereby restoring the reflected pulses R1, R2, and R3 to their initial reflection values by timing means, an exponential generator, and a time gain compensator. Envelope and baseline reject circuits permit the display and accurate location of the time spaced sequence of electric signals having substantially the same amplitude on a measurement scale on a suitable video display or oscilloscope.

Yost, William T. (inventor); Cantrell, John H., Jr. (inventor)

1991-01-01

78

Some experiments on ultrasonic cavitation using a pulsed neutron source  

Microsoft Academic Search

Experiments on the prompt neutron-induced cavitation effect in tetrachloroethylene are described. Cavitation bubbles were detected by the fast acoustic signals they emit, probably during the collapse phase. Using a pulsed fast-neutron source phase locked to the acoustic field, and a time analyser, information was obtained on the history of bubbles which were nucleated at a known phase of the sound

R. Howlett

1968-01-01

79

Pulsed Power for a Dynamic Transmission Electron Microscope  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL) has converted a commercial 200kV transmission electron microscope (TEM) into an ultrafast, nanoscale diagnostic tool for material science studies. The resulting Dynamic Transmission Electron Microscope (DTEM) has provided a unique tool for the study of material phase transitions, reaction front analyses, and other studies in the fields of chemistry, materials science, and biology. The TEM's thermionic electron emission source was replaced with a fast photocathode and a laser beam path was provided for ultraviolet surface illumination. The resulting photoelectron beam gives downstream images of 2 and 20 ns exposure times at 100 and 10 nm spatial resolution. A separate laser, used as a pump pulse, is used to heat, ignite, or shock samples while the photocathode electron pulses, carefully time-synchronized with the pump, function as probe in fast transient studies. The device functions in both imaging and diffraction modes. A laser upgrade is underway to make arbitrary cathode pulse trains of variable pulse width of 10-1000 ns. Along with a fast e-beam deflection scheme, a 'movie mode' capability will be added to this unique diagnostic tool. This talk will review conventional electron microscopy and its limitations, discuss the development and capabilities of DTEM, in particularly addressing the prime and pulsed power considerations in the design and fabrication of the DTEM, and conclude with the presentation of a deflector and solid-state pulser design for Movie-Mode DTEM.

dehope, w j; browning, n; campbell, g; cook, e; king, w; lagrange, t; reed, b; stuart, b; Shuttlesworth, R; Pyke, B

2009-06-25

80

Evaluation of the transmission line model for couplant layer corrections in pulse-echo measurements.  

PubMed

An acoustic couplant layer plays an integral role in many ultrasonic nondestructive testing and material characterization applications. It is important to account for this layer for accurate time-delay measurements. In pulse-echo measurements, the couplant layer can be accounted for by modeling the frequency dependence of phase delay. In this paper, two such models are evaluated for robustness in determining an accurate phase velocity: a simple linear relationship and the acoustic transmission line with its associated nonlinear expression. For this evaluation, measurements of acoustic phase delay in an aluminum sample were made by the pulse-echo method using tone bursts of 1800 different carrier frequencies between 35 and 125 MHz. The transmission line model was fit to the measured data using an unconstrained nonlinear least squares fitting routine with two free parameters: the acoustic phase velocity in the sample and the couplant thickness. It was found that this nonlinear model was extremely sensitive to the initial parameter guesses and could not unambiguously determine both the couplant layer thickness and acoustic phase velocity. In contrast, the faster and simpler linear least squares fit to the delay data determines a unique phase velocity in agreement with resonant ultrasound spectroscopy, an independent measurement technique. PMID:23661128

Sturtevant, Blake; Pantea, Cristian; Sinha, Dipen

2013-05-01

81

Testing ultrasonic pulsed Doppler instruments with a physiologic string phantom.  

PubMed

The spatial, temporal, and frequency resolution of conventional ultrasonic Doppler instruments and the time/space distortions in two-dimensional color Doppler imaging systems can be measured using a pulsatile moving string target. The diameter of the string is small compared with the Doppler sample volume, the velocity (speed and direction), acceleration and timing of the string motions are precisely known with reference to the R wave timing mark, and the spatial location of the string is known. A loop of surgical thread or monofilament fishline running between pulleys is driven by a motor that provides constant string speeds from 0.05 to 150 cm/s and variable string speeds programmed to mimic arterial velocity waveforms from the carotid, aortic, and femoral arteries. Constant string speeds are used to evaluate the Doppler sensitivity, frequency processing, and sample volume size; pulsatile movement of the string provides a physiologic model to evaluate the temporal performance of conventional Doppler systems and the temporal and spatial performance of two-dimensional color Doppler imaging scanners. PMID:2204713

Phillips, D J; Hossack, J; Beach, K W; Strandness, D E

1990-08-01

82

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

NASA Astrophysics Data System (ADS)

In this present work, we develop a new ultrasonic echo pulse method in order to study the feasibility of maturity assessment of orange fruit. This study concerns two varieties of orange (Navel and Mandarin) which are the most harvested in the region of Souss-Massa-Dr?a in Morocco. We worked in the range of high frequencies by the means of a focusing transducer with 20MHz as a central frequency. By taking into account the strong attenuation of the ultrasounds in the texture of fruits and vegetables, we limited our study only to the external layer of orange peel. This control is based mainly on the measure of the ultrasonic parameters eventually velocity and attenuation in order to check the aptitude of this technique to detect the maturity degree of the fruit without passing by penetrometric and biochemical measurements which are generally destructives but the mostly correlated with human perception concerning the firmness of the fruit.

Aboudaoud, I.; Faiz, B.; Aassif, E.; Moudden, A.; Izbaim, D.; Abassi, D.; Malainine, M.; Azergui, M.

2012-12-01

83

Constant frequency pulsed phase-locked-loop instrument for measurement of ultrasonic velocity  

NASA Technical Reports Server (NTRS)

A new instrument based on a constant-frequency pulsed phase-locked-loop (CFPPLL) concept has been developed to accurately measure the ultrasonic wave velocity in liquids and changes in ultrasonic wave velocity in solids and liquids. An analysis of the system shows that it is immune to many of the frequency-dependent effects that plague other techniques. Measurements of the sound velocity in ultrapure water are used to confirm the analysis. The results are in excellent agreement with values from the literature, and establish that the CFPPLL provides a reliable, accurate way to measure velocities, as well as for monitoring small changes in velocity without the sensitivity to frequency-dependent phase shifts common to other measurement systems. The estimated sensitivity to phase changes is better than a few parts in 10 to the 7th.

Yost, William T.; Cantrell, John H.; Kushnick, Peter W.

1991-01-01

84

Analysis of Doppler Effect on the Pulse Compression of Different Codes Emitted by an Ultrasonic LPS  

PubMed Central

This work analyses the effect of the receiver movement on the detection by pulse compression of different families of codes characterizing the emissions of an Ultrasonic Local Positioning System. Three families of codes have been compared: Kasami, Complementary Sets of Sequences and Loosely Synchronous, considering in all cases three different lengths close to 64, 256 and 1,024 bits. This comparison is first carried out by using a system model in order to obtain a set of results that are then experimentally validated with the help of an electric slider that provides radial speeds up to 2 m/s. The performance of the codes under analysis has been characterized by means of the auto-correlation and cross-correlation bounds. The results derived from this study should be of interest to anyone performing matched filtering of ultrasonic signals with a moving emitter/receiver. PMID:22346670

Paredes, José A.; Aguilera, Teodoro; Álvarez, Fernando J.; Lozano, Jesús; Morera, Jorge

2011-01-01

85

Vacuum transmission lines for pulse sharpening and diagnostics applications  

SciTech Connect

We investigated the propagation of MV electrical pulses along coaxial transmission lines (TL) in vacuum with network simulations and experiments. One goal was to establish how well a 3 m-long TL would sharpen the output pulse of a relativistic electron beam accelerator. Sharpening occurs as the cathode of the TL emits electrons and the current flow forces the TL into magnetic cut-off. The other goal was to determine how well field emission must be suppressed in a TL to avoid distortion of a propagating pulse. Simulations predict a four-fold risetime improvement (8 ns to 2 ns) through magnetic insulation in a TL with an electrical length (10 ns) comparable to the risetime of the input pulse. In the laboratory we have shown a five-fold improvement (15 to 3 ns) with a velvet covered 3-m line and a 7.5 fold improvement (2 ns) when a vacuum flashover switch was incorporated between the first third and the last two thirds of the TL. Simple arguments and TL simulations suggest that even a small fraction (1 or 2%) of Child-Langmuir (CL) space charge limited emission will distort a propagating voltage pulse. This result is of particular importance when the TL is part of a voltage diagnostic system.

Di Capua, M.S.; Goerz, D.A.; Freytag, E.K.

1987-06-01

86

Effect of the pulse trajectory on ultrasonic fluid velocity measurement  

NASA Astrophysics Data System (ADS)

In a general situation a non-uniform velocity field gives rise to a shift of the otherwise straight acoustic pulse trajectory between the transmitter and receiver transducers of a sonic anemometer. The aim of this paper is to determine the effects of trajectory shifts on the velocity as measured by the sonic anemometer. This determination has been accomplished by developing a mathematical model of the measuring process carried out by sonic anemometers; a model which includes the non-straight trajectory effect. The problem is solved by small perturbation techniques, based on the relevant small parameter of the problem, the Mach number of the reference flow, M. As part of the solution, a general analytical expression for the deviations of the computed measured speed from the nominal speed has been obtained. The correction terms of both the transit time and of the measured speed are of M 2 order in rotational velocity field. The method has been applied to three simple, paradigmatic flows: one-directional horizontal and vertical shear flows, and mixed with a uniform horizontal flow.

Franchini, S.; Sanz-Andrés, A.; Cuerva, A.

2007-12-01

87

Spark ultrasonic transducer  

NASA Technical Reports Server (NTRS)

Nondestructive testing by spark transducer induces ultrasonic pulses in materials without physical contact. High power pulse generator connected to step up transformer produces sparking between two tungsten rods and ultrasonic energy pulses in test samples placed between rods.

Hoop, J. M.

1972-01-01

88

Reflection and transmission of guided ultrasonic plate waves by vertical stiffeners.  

PubMed

Ultrasonic guided waves are very useful for structural health monitoring. They have the potential to interrogate and detect damage in a structure over a large area with few transducers. Guided plate modes (Lamb waves) are used and proposed for damage detection at a distance in semi-monococque structures such as airplane fuselages and spacecraft structures. The interaction of guided plate waves with stiffening members such as ribs, stringers, or the integral stiffeners used in spacecraft structures limits the distance over which structural health monitoring non-destructive evaluation systems can detect damage. This paper develops a simple explanatory model for the scattering of low-order ultrasonic Lamb waves crossing a stiffening device. The model illuminates the underlying mechanics of waves crossing a stiffener. The model shows that stop-bands for transmission of S(0) (longitudinal pressure) waves across a stiffener line up with flexural resonances of the stiffener. It also demonstrates why transmission of A(0) (flexural) waves is more complicated and harder to predict. The model is shown to agree well with both boundary element method calculations and experimental measurements. PMID:24993204

Reusser, Ricky S; Holland, Stephen D; Chimenti, D E; Roberts, Ron A

2014-07-01

89

Realization of a dispersive delay line for an ultrasonic non-destructive testing system using pulse compression  

Microsoft Academic Search

The key element in the implementation of an ultrasonic pulse compression system for non-destructive testing is the dispersive delay device. From system considerations it is concluded that an ultrasonic strip delay line is the most appropriate device to be used in the system. The design as well as the characteristics of a 1–8 MHz aluminium strip delay line having a linear

F. K. LAM

1977-01-01

90

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

NASA Astrophysics Data System (ADS)

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.

Sietins, Jennifer Mueller

91

Ultrasonic ranging and data telemetry system  

DOEpatents

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.

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

92

Transmission properties of terahertz pulses through subwavelength double split-ring resonators  

E-print Network

Transmission properties of terahertz pulses through subwavelength double split-ring resonators Abul 1, 2005 We present a terahertz time-domain spectroscopy study of the transmission properties of the SRRs on the transmission properties of terahertz pulses in normal-incidence geometry. In one of the SRR

93

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

PubMed

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

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

2014-07-01

94

Structural and elastic determinants of axial transmission ultrasonic velocity in the human radius  

NASA Astrophysics Data System (ADS)

Accurate clinical interpretation of the sound velocity derived from axial transmission devices requires a detailed understanding of the propa-gation phenomena involved and of the bone factors that have an impact on measurements. In the low-megahertz range, ultrasonic propagation in cortical bone depends on anisotropic elastic tissue properties, porosity, and the spatial dimensions, e.g., cortical thickness. A subset of ten human radius samples from a previous biaxial transmission investigation was inspected using 50-MHz scanning acoustic microscopy (SAM) and synchrotron radiation computed tomography (SR-CT). Low-frequency axial transmission sound speed at 1 and 2 MHz was related to structural properties (cortical thickness C.Th, porosity POR, Haversian cavity density CDH) and tissue parameters (acoustic impedance Z, mineral density MD) on site-matched cross sections. Significant linear multivariate regression models (1 MHz: R=0.84, p<1E-4, 2 MHz: R=0.65, p<1E-4) were found for the combination of C.Th with POR and Z (measured in the external cortical quarter). A modified model accounting for the nonlinear dispersion relation with C.Th was also highly significant (R=0.75, p<1E-4, rmse=49.22 m/s) and explained (after adjustment for dispersion) 55.6% of the variance of the sound velocity by variations of porosity (15.6%) and impedance (40%).

Raum, Kay; Leguerney, Ingrid; Chandelier, Florent; Talmant, Maryline; Saied, Amena; Laugier, Pascal; Peyrin, Françoise

2004-10-01

95

Evaluation Techniques for Austenitic Stainless Steels through Tensile Deformation by Analyzing Ultrasonic Pulse Waves in the Frequency Domain  

NASA Astrophysics Data System (ADS)

This paper describes a technique for evaluating the structural variations that tensile deformation induces in austenitic stainless steels. By using fast Fourier transform processing to analyze the spectral distributions of ultrasonic pulse waveforms, I quantitatively investigate the relationship between the spectral distributions of pulse echoes and the internal structures of SUS304 and SUS310 stainless steel. The spectral distributions are obtained by the zero-crossing method and the relationship between the spectral distributions and ultrasonic attenuation caused by grain scattering are discussed. With increasing elongation, the spectral peak frequency and Q value increase for SUS304 steel and are nearly constant for SUS310 steel. The results for SUS304 steel are attributed to martensite transformation, which results in smaller grain size and a corresponding reduction of the attenuation coefficient due to the ultrasonic scatterings.

Honjoh, Katsuhiko

1994-03-01

96

A New Transmission Method for Pulse-Code Modulation Communication Systems  

Microsoft Academic Search

This paper presents the results of a study of the basic factors underlying the selection of a preferable method of transmission for pulse-code modulation communication systems. A new method of transmission, called biternary, is described and is compared with quaternary transmission, as a means of doubling the channel capacity of PCM systems without requiring increased bandwidth or transmission facilities. It

A. Brogle

1960-01-01

97

326 ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 52, no. 2, february 2005 Capacitive Micromachined Ultrasonic  

E-print Network

, february 2005 Capacitive Micromachined Ultrasonic Transducer Design for High Power Transmission Baris operation, designed for high-power transmission, allowed the application of pulse voltages larger than, respectively. Therefore, collapse-snapback operation of the cMUTs was superior for high-power transmission. I

Khuri-Yakub, Butrus T. "Pierre"

98

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

SciTech Connect

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.

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

99

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

NASA Astrophysics Data System (ADS)

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.

Liu, Yang; Chen, Wen-Li; Bond, Leonard J.; Hu, Hui

2014-02-01

100

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

NASA Technical Reports Server (NTRS)

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.

Roth, Don J. (Inventor)

1995-01-01

101

Measurements of Elastic Properties of Plasma-Sprayed Coatings Using Bulk Ultrasonic Pulses  

NASA Astrophysics Data System (ADS)

A new theory is proposed to extend the limit of the application of bulk ultrasonic pulses, which have been thought to be unsuitable for the evaluation of sound velocity in thin coating layers because of interference with echoes. This extension is accomplished by introducing the new concept of the group delay spectrum. We first made a model representing waves reflected from a coating layer and found that many acoustic properties, for example, sound velocity, acoustic impedance, and coating density, can be derived easily by a group delay analysis. Next, the theory was applied to the analysis of a layer plasma-sprayed coated with alumina particles on a stainless steel substrate. To confirm the validity of the theory, we prepared coated specimens of varying thicknesses which covered from 0.16 mm to 0.48 mm, and we succeeded in evaluating sound velocity and coating density.

Sugasawa, Shinobu

2004-05-01

102

A comparative study of experimental and simulated ultrasonic pulse-echo signals from multilayered structures  

NASA Technical Reports Server (NTRS)

The effect on the system acoustic response of variations in the adhesive thickness, coupling thickness, and paint thickness is considered. Both simulations and experimental measurements are used to characterize and classify A-scans from test regions, and to study the effects of various parameters such as paint thickness and epoxy thickness on the variations in the reflected signals. A 1D model of sound propagation in multilayered structures is used to verify the validity of the measured signals, and is also used to computationally generate signals for a class of test locations with gradually varying parameters. This approach exploits the ability of numerical simulations to provide a good understanding of the ultrasonic pulses reflected at disbonds.

Abedin, M. N.; Prabhu, D. R.; Winfree, W. P.; Johnston, P. H.

1992-01-01

103

Pulsed eddy current and ultrasonic data fusion applied to stress measurement  

NASA Astrophysics Data System (ADS)

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.

Habibalahi, A.; Safizadeh, M. S.

2014-05-01

104

Transmission errors and forward error correction in embedded differential pulse code modulation  

Microsoft Academic Search

Formulas are derived for the combined effects of quantization and transmission errors on embedded Differential Pulse Code Modulation (DPCM) performance. The present analysis, which is both more general and precise than previous work on transmission errors in digital communication of analog signals, includes as its special cases the conventional DPCM and Pulse code Modulation. An SNR formula is obtained in

D. J. Goodman; C.-E. Sundberg

1983-01-01

105

Asymptotic breathing pulse in optical transmission systems with dispersion compensation Ildar Gabitov  

E-print Network

Asymptotic breathing pulse in optical transmission systems with dispersion compensation Ildar of the formation of a breathing solitary wave in the optical transmission systems with periodic amplification propagation of such breathing pulse over long distances. We have derived approximate equations describing

Gabitov, Ildar

106

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

E-print Network

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

Khuri-Yakub, Butrus T. "Pierre"

107

Hydraulic Fracture Propagation through Preexisting Discontinuity Monitored by Acoustic Emission and Ultrasonic Transmission  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing is critical to enhance hydrocarbon production from ultra-low permeability unconventional reservoirs, and is the common completion methodology for tight formations around the world. Unfortunately, these reservoirs are often highly heterogeneous and their heterogeneity imparts a degree of geometrical complexity in hydraulic fractures that is poorly understood. Fracture complexity (e.g. branching) results in higher surface area and could be beneficial to production provided it remains conductive. Understanding the sources and consequences of fracture complexity is thus of high importance to completion and production operations. In this study we postulate that textural complexity in tight heterogeneous formations induces fracture complexity, and that the main sources of textural complexity are associated with veins, bed boundaries, lithologic contacts, and geologic interfaces. We thus study the effect of interfaces on hydraulic fracture propagation under laboratory conditions by Acoustic Emission (AE) and Ultrasonic Transmission (UT) monitoring techniques. The experiments were conducted on low permeability sandstone blocks of 279 x 279 x 381 mm length with saw cut discontinuities oriented orthogonally to the expected direction of fracture propagation. The rock is loaded in a poly-axial test frame to representative effective in-situ stress conditions of normal and deviatoric stress. Hydraulic fracturing was initiated by injection of silicon oil into a borehole drilled off center from the block. Acoustic emission (AE) events were continuously monitored during testing using nineteen P-wave sensors. Additional sensors were installed to periodically monitor ultrasonic transmission (UT) along various directions oblique and perpendicular to the fracture and the interface. The AE and UT data were recorded using a Vallen AMSY-6 system, with 16-bit amplitude resolution and 5 MHz sampling rate. Detailed analysis of AE localizations allowed us to identify various stages of hydraulic fracturing, including fracture initiation, fracture interaction with the preexisting interface, fracture propagation and fracture closing. Observed variations in UT amplitudes and velocities, during fracture propagation, were related to fracture propagation, as well as to the penetration of fracturing fluid to the conductive interface. Analysis of the combined AE and UT data provides additional insight into the fracturing process and significantly improved our understanding of the dynamics of hydraulic fracture propagation. Detailed post-test 3D mapping of the final fracture allowed us to make an independent comparison of actual fracture and the fracture monitored by the AE and UT measurements. This comparison is essential for validating the interpretation of microseismic monitoring during hydraulic fracturing in the lab and in the field.

Stanchits, S.; Lund, J.; Surdi, A.; Edelman, E.; Whitney, N.; Eldredge, R.; Suarez-Rivera, R.

2011-12-01

108

SIMULATIONS OF LASER PULSE COUPLING AND TRANSMISSION EFFICIENCY IN PLASMA CHANNELS  

E-print Network

SIMULATIONS OF LASER PULSE COUPLING AND TRANSMISSION EFFICIENCY IN PLASMA CHANNELS R. E. Giacone, D the acceleration length. Energy efficient coupling of laser pulses in plasma channels is of critical importance size oscillations. ENERGY COUPLING OF LASER PULSES IN A PLASMA CHANNEL In this section we present 2D

Geddes, Cameron Guy Robinson

109

Generation of subpicosecond electrical pulses by nonuniform illumination of GaAs transmission-line gaps  

Microsoft Academic Search

We present a detailed study of subpicosecond pulse generation by nonuniform illumination of transmission-line gaps on semiinsulating GaAs. The dependence of such pulses on bias voltage, light intensity, and wavelength was examined in detail with the aid of a subpicosecond electrooptic sampling system. A complete spatial mapping of the excitation area indicates that the pulse generation is due to the

Sotiris Alexandrou; Chia-Chi Wang; Roman Sobolewski; Thomas Y. Hsiang

1994-01-01

110

Transmission properties of terahertz pulses through an ultrathin subwavelength silicon hole array  

E-print Network

Transmission properties of terahertz pulses through an ultrathin subwavelength silicon hole array 30 March 2005 We demonstrate extraordinary THz transmission of an array of subwavelength apertures patterned on ultrathin highly doped silicon by reactive ion etching. The zero-order transmission spectra

111

Three-dimensional simulations of ultrasonic axial transmission velocity measurement on cortical bone models  

NASA Astrophysics Data System (ADS)

The ultrasonic axial transmission technique, used to assess cortical shells of long bones, is investigated using numerical simulations based on a three-dimensional (3D) finite difference code. We focus our interest on the effects of 3D cortical bone geometry (curvature, cortical thickness), anisotropy, and microporosity on speed of sound (SOS) measurements for different frequencies in the MHz range. We first show that SOS values measured on tubular cortical shells are identical to those measured on cortical plates of equal thickness. Anisotropy of cortical bone is then shown to have a major impact on SOS measurement as a function of cortical thickness. The range of SOS values measured on anisotropic bone is half the range found when bone is considered isotropic. Dependence of thickness occurs for cortical shell thinner than 0.5×?bone in anisotropic bone (?bone: wavelength in bone), whereas it occurs for cortical shell thinner than ?bone when anisotropy is neglected. Sensitivity of SOS along the bone axis to intracortical microporosity is shown to be approximately -20 m s-1 per percent of porosity. Using homogenized porous bone, we finally show that the cortical depth that contributes to lateral wave SOS measurement is approximately 1-1.5 mm for frequencies ranging from 500 kHz to 2 MHz under classical in vivo measurement conditions.

Bossy, Emmanuel; Talmant, Maryline; Laugier, Pascal

2004-05-01

112

Modeling and phantom studies of ultrasonic wall shear rate measurements using coded pulse excitation.  

PubMed

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 degrees 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

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

2006-04-01

113

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

114

Monitoring fresh concrete by ultrasonic transmission measurements: Exploratory multi-way analysis of the spectral information  

Microsoft Academic Search

The setting of concrete can be monitored by measuring the characteristics of ultrasonic waves sent through a fresh sample at regular intervals. So far, the development of this ultrasonic method has mainly focussed on the wave velocity for technical reasons. However, the frequency spectrum might contain even more information since it takes the entire received signal into account. Therefore, the

Nicolas Robeyst; Christian U. Grosse; Nele De Belie

2009-01-01

115

Continued Evaluation of the Pulse-Echo Ultrasonic Instrument for Critical Velocity Determination during Hanford Tank Waste Transfer Operations  

SciTech Connect

Laboratory (PNNL) conducted an extensive evaluation of the ability of three ultrasonic instruments to detect critical velocity for a broad range of simulated Hanford nuclear waste streams containing particles with mean particle sizes of >50 microns. Evaluations were perform using the pipe loop at the Process Development Laboratory – East (PDL-E) at PNNL that was designed and built to evaluate the pipeline plugging issue during slurry transfer operations at the Hanford Waste Treatment Plant. In 2011 the ability of the ultrasonic PulseEcho system to detect critical velocity continued to be evaluated using the PDL-E flow loop and new simulants containing high-density particles with a mean particle size of < 15 microns. The PDL-E flow loop was modified for the 2011 testing to include a new test section that contained 5-MHz and 10-MHz ultrasonic transducers non-invasively mounted to schedule 40 pipe. The test section also contained reference instrumentation to facilitate direct comparison of the real-time PulseEcho transducer responses with experimentally observed critical velocities. This paper presents the results from the 2011 PulseEcho evaluation using a variety of simulated Hanford nuclear waste streams that were selected to encompass the expected high-level waste feed properties.

Denslow, Kayte M.; Bontha, Jagannadha R.; Adkins, Harold E.; Jenks, Jeromy WJ; Burns, Carolyn A.; Schonewill, Philip P.; Hopkins, Derek F.; Thien, Michael G.; Wooley, Theodore A.

2012-04-01

116

Brillouin scattering properties in partially chlorinated plastic optical fibers estimated with ultrasonic pulse-echo technique  

NASA Astrophysics Data System (ADS)

With their high thermal stability compared with other plastic optical fibers (POFs), partially chlorinated graded-index POFs (PCGI-POFs) are a promising candidate to develop the sensing heads of Brillouin-based distributed strain and temperature sensors. In this study, the Brillouin frequency shift (BFS) and its temperature dependence in a PCGI-POF are estimated by using ultrasonic pulse-echo technique. The estimated BFS is ~4.43 GHz with its temperature coefficient of approximately -6.9 MHz/K at 1550 nm. Its absolute value is ~5.8 times as large as that of silica single-mode fibers, and even larger than that of a perflurointated GI-POF. Its fracture strain of ~3.0% (mostly in elastic region) is small compared with other POFs, and so it appears difficult to estimate the BFS dependence on strain in a PCGI-POF with this technique. These experimental results imply that the Brillouin scattering in PCGI-POFs is potentially applicable to highprecision temperature sensing.

Minakawa, Kazunari; Hayashi, Neisei; Mizuno, Yosuke; Nakamura, Kentaro

2013-05-01

117

Fiber Optic Picosecond Laser Pulse Transmission Line for Hydrogen Ion Beam Profile Measurement  

SciTech Connect

We present a fiber optic laser pulse transmission line for non-intrusive longitudinal profile measurement of the hydrogen ion (H-) beam at the front-end of the Spallation Neutron Source (SNS) accelerator. The 80.5 MHz, 2.5 ps, multi-killowatt optical pulses are delivered to the accelerator beam line through a large mode area polarization maintaining optical fiber to ensure a high measurement stability. The transmission efficiency, output laser beam quality, pulse jitter and pulse width broadening over a 100-ft fiber line are experimentally investigated. A successful measurement of the H- beam microbunch (~130 ps) profile is obtained. Our experiment is the first demonstration of particle beam profile diagnostics using fiber optic laser pulse transmission line.

Liu, Yun [ORNL; Huang, Chunning [ORNL; Aleksandrov, Alexander V [ORNL

2013-01-01

118

Transmission time and bandwidth in pulse code modulation (application of the statistical thermodynamic formalism)  

Microsoft Academic Search

Employing the “statistical thermodynamic formalism” developed in an earlier paper, it is possible to determine “compact” sets of transmission times for the words of PCM (pulse code modulation) messages. In particular, we deal with pulses of zero or unit heights. These compact signals, which lead to shorter message times and eliminate redundancy even when successive words are correlated (Markov source),

C. Huang; H. Reiss

1971-01-01

119

The effect of constant and pulse vaccination on SIR epidemic model with horizontal and vertical transmission  

Microsoft Academic Search

A SIR epidemic model with horizontal and vertical transmission is presented. The dynamics of this disease model under constant and pulse vaccination are analyzed. Theoretical results show that under constant vaccination, the dynamic behavior is similar to no vaccination. But under a planned pulse vaccination regime, the system converges to a stable periodic solution with the number of infectious individuals

Lansun Chen

2002-01-01

120

Pulsed Power for a Dynamic Transmission Electron Microscope  

Microsoft Academic Search

Lawrence Livermore National Laboratory (LLNL) has converted a commercial 200kV transmission electron microscope (TEM) into an ultrafast, nanoscale diagnostic tool for material science studies. The resulting Dynamic Transmission Electron Microscope (DTEM) has provided a unique tool for the study of material phase transitions, reaction front analyses, and other studies in the fields of chemistry, materials science, and biology. The TEM's

w j dehope; n browning; g campbell; e cook; w king; t lagrange; b reed; b stuart; R Shuttlesworth; B Pyke

2009-01-01

121

Real-time measurement of ice growth during simulated and natural icing conditions using ultrasonic pulse-echo techniques  

NASA Technical Reports Server (NTRS)

Results of tests to measure ice accretion in real-time using ultrasonic pulse-echo techniques are presented. Tests conducted on a 10.2 cm diameter cylinder exposed to simulated icing conditions in the NASA Lewis Icing Research Tunnel and on an 11.4 cm diameter cylinder exposed to natural icing conditions in flight are described. An accuracy of + or - 0.5 mm is achieved for real-time ice thickness measurements. Ice accretion rate is determined by differentiating ice thickness with respect to time. Icing rates measured during simulated and natural icing conditions are compared and related to icing cloud parameters. The ultrasonic signal characteristics are used to detect the presence of surface water on the accreting ice shape and thus to distinguish between dry ice growth and wet growth. The surface roughness of the accreted ice is shown to be related to the width of the echo signal received from the ice surface.

Hansman, R. J., Jr.; Kirby, M. S.

1986-01-01

122

Applications of tunable high energy/pressure pulsed lasers to atmospheric transmission and remote sensing  

NASA Technical Reports Server (NTRS)

Atmospheric transmission of high energy C12 O2(16) lasers were improved by pulsed high pressure operation which, due to pressure broadening of laser lines, permits tuning the laser 'off' atmospheric C12 O2(16) absorption lines. Pronounced improvement is shown for horizontal transmission at altitudes above several kilometers, and for vertical transmission through the entire atmosphere. The atmospheric transmission of tuned C12 O2(16) lasers compares favorably with C12 O2(18) isotope lasers and CO lasers. The advantages of tunable, high energy, high pressure pulsed lasers over tunable diode lasers and waveguide lasers, in combining high energies with a large tuning range, are evaluated for certain applications to remote sensing of atmospheric constituents and pollutants. Pulsed operation considerably increases the signal to noise ratio without seriously affecting the high spectral resolution of signal detection obtained with laser heterodyning.

Hess, R. V.; Seals, R. K.

1974-01-01

123

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

DOEpatents

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.

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

2000-01-01

124

Terahertz pulse transmission in plastic photonic crystal fibres  

Microsoft Academic Search

Guided-wave single-mode propagation of sub-ps terahertz (THz) pulses in a plastic photonic crystal fibre has been experimentally demonstrated. The plastic photonic crystal fibre (PPCF) is fabricated from high-density polyethylene tubes and filaments. The fibre exhibits low loss and relatively low dispersive propagation of THz pulses within the experimental bandwidth of 0.1-3 THz. Such PPCFs have the promise of low loss,

M. Cho; J. Kim; H. Han

2002-01-01

125

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

PubMed

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

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

1992-01-01

126

Ultrasonics 36 ( 1998) 25~29 Miniature drumheads: microfabricated ultrasonic transducers  

E-print Network

Ultrasonics 36 ( 1998) 25~29 Miniature drumheads: microfabricated ultrasonic transducers I'A 94305. USA Abstract Significant improvement in the performance of capacitive microfabricated ultrasonic-coupled through-transmission; Capacitive ultrasonic transducer: Immersion transducer: Microfabrication process

Khuri-Yakub, Butrus T. "Pierre"

127

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

DOEpatents

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.

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

2013-02-12

128

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

SciTech Connect

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.

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

129

Nonlinear optical generation and detection of ultrashort electrical pulses in transmission lines.  

PubMed

The nonlinear optical generation and detection of subpicosecond electrical pulses on coplanar transmission lines is demonstrated. The electrical pulses are generated by optical rectification of ultrashort optical pulses and detected by electro-optic sampling. Both processes are the result of a second-order nonlinear optical response that occurs in the same poled polymer medium. A bipolar temporal waveform with a FWHM duration of 180 fs for the positive lobe that was measured after a propagation distance of 125 mum was observed. Pulse broadening was minimized by careful attention to the device structure. PMID:18040332

Nahata, A

2001-03-15

130

Pulse-Echo Phased Array Ultrasonic Inspection of Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS)  

NASA Technical Reports Server (NTRS)

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. Keywords: Phased Array, Ultrasonics, Composites, Out-of-Autoclave

Johnston, Pat H.

2010-01-01

131

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

PubMed

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

Ozeri, Shaul; Shmilovitz, Doron

2014-09-01

132

High pulse repetition frequency, multiple wavelength, pulsed CO2 lidar system for atmospheric transmission and target reflectance measurements  

NASA Astrophysics Data System (ADS)

A multiple wavelength, pulsed CO2 lidar system operating at a pulse repetition frequency of 200 Hz and permitting the random selection of CO2 laser wavelengths for each laser pulse is presented. This system was employed to measure target reflectance and atmospheric transmission by using laser pulse bursts consisting of groups with as many as 16 different wavelengths at a repetition rate of 12 Hz. The wavelength tuning mechanism of the transversely excited atmospheric laser consists of a stationary grating and a flat mirror controlled by a galvanometer. Multiple wavelength, differential absorption lidar (DIAL) measurements reduce the effects of differential target reflectance and molecular absorption interference. Examples of multiwavelength DIAL detection for ammonia and water vapor show the dynamic interaction between these two trace gases. Target reflectance measurements for maple trees in winter and autumn are presented.

Ben-David, Avishai; Emery, Silvio L.; Gotoff, Steven W.; D'Amico, Francis M.

1992-07-01

133

Pulse-excited, auto-zeroing multiple channel data transmission system  

DOEpatents

A multiple channel data transmission system is provided in which signals from a plurality of pulse operated transducers and a corresponding plurality of pulse operated signal processor channels are multiplexed for single channel FM transmission to a receiving station. The transducers and corresponding channel amplifiers are powered by pulsing the dc battery power to these devices to conserve energy and battery size for long-term data transmission from remote or inaccessible locations. Auto zeroing of the signal channel amplifiers to compensate for drift associated with temperature changes, battery decay, component aging, etc., in each channel is accomplished by means of a unique auto zero feature which between signal pulses holds a zero correction voltage on an integrating capacitor coupled to the corresponding channel amplifier output. Pseudo-continuous outputs for each channel are achieved by pulsed sample-and-hold circuits which are updated at the pulsed operation rate. The sample-and-hold outputs are multiplexed into an FM/FM transmitter for transmission to an FM receiver station for demultiplexing and storage in separate channel recorders.

Fasching, G.E.

1985-02-22

134

Pulse-excited, auto-zeroing multiple channel data transmission system  

DOEpatents

A multiple channel data transmission system is provided in which signals from a plurality of pulse operated transducers and a corresponding plurality of pulse operated signal processor channels are multiplexed for single channel FM transmission to a receiving station. The transducers and corresponding channel amplifiers are powered by pulsing the dc battery power to these devices to conserve energy and battery size for long-term data transmission from remote or inaccessible locations. Auto zeroing of the signal channel amplifiers to compensate for drift associated with temperature changes, battery decay, component aging, etc., in each channel is accomplished by means of a unique auto zero feature which between signal pulses holds a zero correction voltage on an integrating capacitor coupled to the corresponding channel amplifier output. Pseudo-continuous outputs for each channel are achieved by pulsed sample-and-hold circuits which are updated at the pulsed operation rate. The sample-and-hold outputs are multiplexed into an FM/FM transmitter for transmission to an FM receiver station for demultiplexing and storage in separate channel recorders.

Fasching, George E. (Morgantown, WV)

1987-01-01

135

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

136

Reflection and Transmission of Pulsed Electromagnetic Fields through Multilayered  

E-print Network

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

Oughstun, Kurt

137

Using pulsed neutron transmission for crystalline phase imaging and analysis  

Microsoft Academic Search

The total scattering cross section of polycrystalline materials in the thermal neutron region contains valuable information about the scattering processes that neutrons undergo as they pass through the sample. In particular, it displays characteristic discontinuities or Bragg edges of selected families of lattice planes. We have developed a pixelated time-of-flight transmission detector able to record these features and in this

A. Steuwer; P. J. Withers; J. R. Santisteban; L. Edwards

2005-01-01

138

Pulse transmission mode \\/PTM\\/ Nd:YAG laser for airborne hydrography  

Microsoft Academic Search

The frequency-doubled Nd:YAG laser, operated in pulse transmission mode (PTM), can provide the required performance characteristics for the application of airborne coastal hydrography. This paper describes a PTM Nd:YAG laser operating reliably at pulse repetition frequencies (PRF) of up to 400 Hz. Technical problems encountered include thermal effects in the laser rod, design of suitable Q-switch circuitry, and the problem

M. B. Rankin; N. J. Hall; G. D. Ferguson

1980-01-01

139

Significant pulse-lengthening in a multigigawatt magnetically insulated transmission line oscillator  

Microsoft Academic Search

The Air Force Research Laboratory\\/Phillips Laboratory magnetically insulated transmission line oscillator (MILO) is a gigawatt-class, L-band, high-power microwave tube driven by a 500-kV, 60-kA electron beam. A previous version of this tube generated 1.5 GW pulses, but with significant RF pulse shortening, The paper reports on improvements to the tube that have allowed us to increase the output power by

M. D. Haworth; G. Baca; James N. Benford; T. Englert; K. Hackett; K. J. Hendricks; D. Henley; M. Lacour; R. W. Lemke; D. Price; D. Ralph; M. Sena; D. Shiffler; T. A. Spencer

1998-01-01

140

Improved large tip angle parallel transmission pulse design through a perturbation analysis of the Bloch equation.  

PubMed

Parallel transmission has emerged as an efficient means for implementing multidimensional spatially selective radiofrequency excitation pulses. To date, most theoretical and experimental work on parallel transmission radiofrequency (RF) pulse design is based on the small-tip-angle approximation to the Bloch equation. The small-tip-angle, while mathematically compact, is not an exact solution and leads to significant errors when large-tip-angle pulses are designed. Methods have been proposed to overcome the limitations of the small-tip-angle using regularized least-square optimization or optimal control algorithms. These methods, however, are based on further approximations to the Bloch equation or require the use of general purpose algorithms that do not capitalize fully on the dynamics of the physical model at hand. In this article, a novel algorithm for large-tip-angle parallel transmission pulse design is proposed. The algorithm relies on a perturbation analysis of the Bloch equation and it depicts the relationship between the excited magnetization, its deviation from the target pattern and the desired pulses. Simulations and experiments are used to validate the proposed method on a 7 T 8-channel transmit array. The results demonstrate that the perturbation analysis algorithm provides a fast and accurate approach for multidimensional large-tip-angle pulse design, especially when large acceleration factors and/or echo-planar trajectories are used. PMID:21520270

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

2011-09-01

141

Degree of dispersion monitoring by ultrasonic transmission technique and excitation of the transducer's harmonics  

NASA Astrophysics Data System (ADS)

The degree of dispersion of filled polymer compounds is an important quality parameter for various applications. For instance, there is an influence on the chroma in pigment colored plastics or on the mechanical properties of filled or reinforced compounds. Most of the commonly used offline methods are work-intensive and time-consuming. Moreover, they do not allow an all-over process monitoring. In contrast, the ultrasonic technique represents a suitable robust and process-capable inline method. Here, we present inline ultrasonic measurements on polymer melts with a fundamental frequency of 1 MHz during compounding. In order to extend the frequency range we additionally excite the fundamental and the odd harmonics vibrations at 3 and 5 MHz. The measurements were carried out on a compound consisting of polypropylene and calcium carbonate. For the simulation of agglomerates calcium carbonate with a larger particle size was added with various rates. The total filler content was kept constant. The frequency selective analysis shows a linear correlation between the normalized extinction and the rate of agglomerates simulated by the coarser filler. Further experiments with different types of glass beads with a well-defined particle size verify these results. A clear correlation between the normalized extinction and the glass bead size as well as a higher damping with increasing frequency corresponds to the theoretical assumption. In summary the dispersion quality can be monitored inline by the ultrasonic technique. The excitation of the ultrasonic transducer's harmonics generates more information about the material as the usage of the pure harmonic vibration.

Schober, G.; Heidemeyer, P.; Kretschmer, K.; Bastian, M.; Hochrein, T.

2014-05-01

142

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

SciTech Connect

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.

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

2011-06-23

143

Fundamental aspects of pulse phase-locked loop technology-based methods for measurement of ultrasonic velocity  

NASA Technical Reports Server (NTRS)

A new instrument based on a constant frequency pulse phase-locked loop concept has been developed to accurately measure the ultrasonic phase velocity in condensed matter. Measurements of the sound velocity in ultrapure water are reported in which both damped and undamped transducers are used with the instrument together with reflectors of various thicknesses placed in the sound propagation path. An analysis of measurements made with the new instrument and similar measurements, taken under identical experimental conditions, using a popular variable frequency pulsed-phase-locked loop instrument is reported. Uncertainties in both measurement systems are analyzed and discussed. A method for measuring inherent phase shifts, not addressed by previous investigations, within the variable frequency pulsed phase-locked loop system and a derivation of the equations that govern the overall use of variable frequency systems using phase-sensitive comparisons are presented. The effects of a finite pulse length on the measurements of phase velocity in dispersive media are addressed in detail.

Yost, William T.; Cantrell, John H.; Kushnick, Peter W.

1992-01-01

144

Standard practice for evaluating performance characteristics of ultrasonic Pulse-Echo testing instruments and systems without the use of electronic measurement instruments  

E-print Network

1.1 This practice describes procedures for evaluating the following performance characteristics of ultrasonic pulse-echo examination instruments and systems: Horizontal Limit and Linearity; Vertical Limit and Linearity; Resolution - Entry Surface and Far Surface; Sensitivity and Noise; Accuracy of Calibrated Gain Controls. Evaluation of these characteristics is intended to be used for comparing instruments and systems or, by periodic repetition, for detecting long-term changes in the characteristics of a given instrument or system that may be indicative of impending failure, and which, if beyond certain limits, will require corrective maintenance. Instrument characteristics measured in accordance with this practice are expressed in terms that relate to their potential usefulness for ultrasonic testing. Instrument characteristics expressed in purely electronic terms may be measured as described in E1324. 1.2 Ultrasonic examination systems using pulsed-wave trains and A-scan presentation (rf or video) may be e...

American Society for Testing and Materials. Philadelphia

2011-01-01

145

Noise immunity of data transmission systems using pulse code modulation (Review)  

Microsoft Academic Search

The paper presents a survey of the Soviet literature on the noise immunity of systems of digital single-channel transmission using adaptive pulse code modulation. Emphasis is placed on two approaches: (1) calculation of the system as a whole with allowance for factors that affect noise immunity; and (2) a consistent analysis of the statistical characteristics of analog-digital conversion, of errors

N. I. Pilipchuk

1983-01-01

146

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

Microsoft Academic Search

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

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

2010-01-01

147

The effect of abdominal wall morphology on ultrasonic pulse distortion. Part I. Measurements  

E-print Network

than for fat layers. © 1998 Acoustical Society of America. S0001-4966 98 05911-6 PACS numbers: 43.80.Cs is that poor ultrasonic image quality is primarily associated with obesity.1­3 Although this belief has some to obesity in general, that is, that image quality depends on the individual's body wall struc- ture

Mast, T. Douglas

148

The use of ultrasonic pulse velocity tests for the diagnosis of ancient masonries: the influence of the applied load  

NASA Astrophysics Data System (ADS)

Sophisticated non destructive techniques for the diagnosis of existing masonry structures have been developed and improved throughout the years, such as ground penetrating radar, thermography, sonic and ultrasonic tomography, laser scanner survey, etc.: by using an integrated approach it is possible to reconstruct the morphology of the masonry walls, to detect the presence of cracks and voids, achieving an accurate and reliable diagnosis of the construction, which is the basis for the restoration design. The ultrasonic pulse velocity (UPV) method can be conveniently used to check the quality of stones, but it can be used also for material characterization. Both the intrinsic characteristic of the stone (porosity, grain size, anisotropy, etc.) and the external factors (humidity, stress, temperature, presence of cracks) may affect the elastic wave propagation, thus in order to correctly estimate the ultrasonic behaviour of the material investigated it is important to know in what manner and how much the variation of the experimental conditions may modify the characteristics of the waves being measured. This aspect is of crucial importance when in situ measurements are made. In this work the influence of the applied load on UPV results has been investigated. In particular, the research has been carried out on ashlars and on sample masonry panels made of lime mortar joints and Lecce stone, a soft calcarenitic stone traditionally used in the Lecce district, South of Italy. The presence of load strongly influenced the UPV measures, due to the particular microstructural characteristic of the stone. The work aim at quantify this influence in order to correctly interpret in situ measurements.

Leucci, Giovanni; Vasanelli, Emilia; Calia, Angela; Micelli, Francesco; Aiello, Maria Antonietta

2014-05-01

149

Ultrasonic pulse velocity for the evaluation of physical and mechanical properties of a highly porous building limestone.  

PubMed

UPV as non-destructive technique can effectively contribute to the low invasive in situ analysis and diagnosis of masonry elements related to the conservation, rehabilitation and strengthening of the built heritage. The use of non-destructive and non-invasive techniques brings all the times many advantages in diagnostic activities on pre-existing buildings in terms of sustainability; moreover, it is a strong necessity with respect to the conservation constraints when dealing with the historical-architectural heritage. In this work laboratory experiments were carried out to investigate the effectiveness of ultrasonic pulse velocity (UPV) in evaluating physical and mechanical properties of Lecce stone, a soft and porous building limestone. UPV and selected physical-mechanical parameters such as density and uniaxial compressive strength (UCS) were determined. Factors such as anisotropy and water presence that induce variations on the ultrasonic velocity were also assessed. Correlations between the analysed parameters are presented and discussed. The presence of water greatly affected the values of the analysed parameters, leading to a decrease of UPV and to a strong reduction of the compressive strength. A discussion of the role of the water on these results is provided. Regression analysis showed a reliable linear correlation between UPV and compressive strength, which allows a reasonable estimation of the strength of Lecce stone by means of non-destructive testing methods such as the ultrasonic wave velocity. Low correlation between UPV and density was found, suggesting that other factors than density, related to the fabric and composition, also influence the response of the selected stone to the UPV. They have no influence on the UCS, that instead showed to be highly correlated with the packing density. PMID:25769219

Vasanelli, Emilia; Colangiuli, Donato; Calia, Angela; Sileo, Maria; Aiello, Maria Antonietta

2015-07-01

150

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

Microsoft Academic Search

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

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

1999-01-01

151

Wind turbines and bat mortality: Doppler shift profiles and ultrasonic bat-like pulse reflection from moving turbine blades.  

PubMed

Bat mortality resulting from actual or near-collision with operational wind turbine rotors is a phenomenon that is widespread but not well understood. Because bats rely on information contained in high-frequency echoes to determine the nature and movement of a target, it is important to consider how ultrasonic pulses similar to those used by bats for echolocation may be interacting with operational turbine rotor blades. By assessing the characteristics of reflected ultrasonic echoes, moving turbine blades operating under low wind speed conditions (<6 m s(-1)) were found to produce distinct Doppler shift profiles at different angles to the rotor. Frequency shifts of up to ±700-800 Hz were produced, which may not be perceptible by some bat species. Monte Carlo simulation of bat-like sampling by echolocation revealed that over 50 rotor echoes could be required by species such as Pipistrellus pipistrellus for accurate interpretation of blade movement, which may not be achieved in the bat's approach time-window. In summary, it was found that echoes returned from moving blades had features which could render them attractive to bats or which might make it difficult for the bat to accurately detect and locate blades in sufficient time to avoid a collision. PMID:20968394

Long, Chloe V; Flint, James A; Lepper, Paul A

2010-10-01

152

Energy shadowing correction of ultrasonic pulse-echo records by digital signal processing  

NASA Technical Reports Server (NTRS)

A numerical algorithm is described that enables the correction of energy shadowing during the ultrasonic testing of bulk materials. In the conventional method, an ultrasonic transducer transmits sound waves into a material that is immersed in water so that discontinuities such as defects can be revealed when the waves are reflected and then detected and displayed graphically. Since a defect that lies behind another defect is shadowed in that it receives less energy, the conventional method has a major drawback. The algorithm normalizes the energy of the incoming wave by measuring the energy of the waves reflected off the water/air interface. The algorithm is fast and simple enough to be adopted for real time applications in industry. Images of material defects with the shadowing corrections permit more quantitative interpretation of the material state.

Kishonio, D.; Heyman, J. S.

1985-01-01

153

Numerical modeling and measurement by pulsed television holography of ultrasonic displacement maps in plates with through-thickness defects  

NASA Astrophysics Data System (ADS)

We present a novel numerical modeling of ultrasonic Lamb and Rayleigh wave propagation and scattering by through-thickness defects like holes and slots in homogeneous plates, and its experimental verification in both near and far field by a self-developed pulsed TV holography system. In contrast to rigorous vectorial formulation of elasticity theory, our model is based on the 2-D scalar wave equation over the plate surface, with specific boundary conditions in the defects and plate edges. The experimental data include complex amplitude maps of the out-of-plane displacements of the plate surface, obtained by a two-step spatiotemporal Fourier transform method. We find a fair match between the numerical and experimental results, which allows for quantitative characterization of the defects.

López-Vázquez, J. Carlos; Deán-Ben, X. Luís; Trillo, Cristina; Doval, Ángel F.; Fernández, José L.; Amlani, Faisal; Bruno, Oscar P.

2010-09-01

154

Nonlinear ultrasonic pulsed measurements and applications to metal processing and fatigue  

NASA Astrophysics Data System (ADS)

Nonlinear ultrasonics research at NASA-Langley Research Center emphasizes development of experimental techniques and modeling, with applications to metal fatigue and metals processing. This review work includes a summary of results from our recent efforts in technique refinement, modeling of fatigue related microstructure contributions, and measurements on fatigued turbine blades. Also presented are data on 17-4PH and 410-Cb stainless steels. The results are in good agreement with the models.

Yost, William T.; Cantrell, John H.; Na, Jeong K.

2001-04-01

155

Pulse shaping and extraction of information from ultrasonic reflections in composite materials  

NASA Technical Reports Server (NTRS)

The application of ultrasonic inspection to the nondestructive testing of composite materials is examined with reference to specific examples including monitoring of epoxy curing, evaluation of impact damage in a graphite/epoxy laminate, and monitoring of a repaired area in a composite wing plate. Signal processing methods are described which improve time resolution, facilitating identification of discrete echoes corresponding to events in the material.

Kishoni, Doron

1988-01-01

156

Pulsed Terahertz Transmission Spectroscopy of Liquid CHCl3, CCl4, and their Mixtures B. N. Flanders, R. A. Cheville, D. Grischkowsky, and N. F. Scherer*,  

E-print Network

Pulsed Terahertz Transmission Spectroscopy of Liquid CHCl3, CCl4, and their Mixtures B. N. Flanders are measured by pulsed terahertz time domain transmission spectroscopy. The absorbance spectrum for neat CHCl3

Scherer, Norbert F.

157

Critical evaluation of pulse-echo ultrasonic test method for the determination of setting and mechanical properties of acrylic bone cement: influence of mixing technique.  

PubMed

Currently there is no reliable objective method to quantify the setting properties of acrylic bone cements within an operating theatre environment. Ultrasonic technology can be used to determine the acoustic properties of the polymerising bone cement, which are linked to material properties and provide indications of the physical and chemical changes occurring within the cement. The focus of this study was the critical evaluation of pulse-echo ultrasonic test method in determining the setting and mechanical properties of three different acrylic bone cement when prepared under atmospheric and vacuum mixing conditions. Results indicated that the ultrasonic pulse-echo technique provided a highly reproducible and accurate method of monitoring the polymerisation reaction and indicating the principal setting parameters when compared to ISO 5833 standard, irrespective of the acrylic bone cement or mixing method used. However, applying the same test method to predict the final mechanical properties of acrylic bone cement did not prove a wholly accurate approach. Inhomogeneities within the cement microstructure and specimen geometry were found to have a significant influence on mechanical property predictions. Consideration of all the results suggests that the non-invasive and non-destructive pulse-echo ultrasonic test method is an effective and reliable method for following the full polymerisation reaction of acrylic bone cement in real-time and then determining the setting properties within a surgical theatre environment. However the application of similar technology for predicting the final mechanical properties of acrylic bone cement on a consistent basis may prove difficult. PMID:25260486

Hagan, Christopher P; Orr, John F; Mitchell, Christina A; Dunne, Nicholas J

2015-02-01

158

Transmission mode adaptive beamforming for planar phased arrays and its application to 3D ultrasonic transcranial imaging  

NASA Astrophysics Data System (ADS)

A new adaptive beamforming method for accurately focusing ultrasound behind highly scattering layers of human skull and its application to 3D transcranial imaging via small-aperture planar phased arrays are reported. Due to its undulating, inhomogeneous, porous, and highly attenuative structure, human skull bone severely distorts ultrasonic beams produced by conventional focusing methods in both imaging and therapeutic applications. Strong acoustical mismatch between the skull and brain tissues, in addition to the skull's undulating topology across the active area of a planar ultrasonic probe, could cause multiple reflections and unpredictable refraction during beamforming and imaging processes. Such effects could significantly deflect the probe's beam from the intended focal point. Presented here is a theoretical basis and simulation results of an adaptive beamforming method that compensates for the latter effects in transmission mode, accompanied by experimental verification. The probe is a custom-designed 2 MHz, 256-element matrix array with 0.45 mm element size and 0.1mm kerf. Through its small footprint, it is possible to accurately measure the profile of the skull segment in contact with the probe and feed the results into our ray tracing program. The latter calculates the new time delay patterns adapted to the geometrical and acoustical properties of the skull phantom segment in contact with the probe. The time delay patterns correct for the refraction at the skull-brain boundary and bring the distorted beam back to its intended focus. The algorithms were implemented on the ultrasound open-platform ULA-OP (developed at the University of Florence).

Shapoori, Kiyanoosh; Sadler, Jeffrey; Wydra, Adrian; Malyarenko, Eugene; Sinclair, Anthony; Maev, Roman G.

2013-03-01

159

Analog pulse compression system for real-time ultrasonic non-destructive testing  

Microsoft Academic Search

An analog pulse compression system based on the use of a magnetoacoustic storage correlator as a pulse compressor is proposed, and a real-time operation of the system is demonstrated. The system offers good flexibility; it is not limited to any particular type of large time-bandwidth signal.

Vladimir Ermolov; Jyrki Stor-Pellinen; Mauri Luukkala

1996-01-01

160

DONAR - A computer processing system to extend ultrasonic pulse-echo testing.  

NASA Technical Reports Server (NTRS)

A dedicated general purpose digital computer has been built on the principle of a sampled-data system to run an ultrasonic subsystem under programmed control. A most significant application is the ability to extract a signal from an interfering background. As illustrated in the paper, a 1 mm diameter transducer was used to measure the diameter of a 2.5 mm OD plastics tube with 0.4 mm wall thickness. Echoes from all four surfaces were displayed and the measurements indicated an uncertainty of less than 0.1 mm.

Lees, S.; Gerhard, F. B.; Barber, F. E.; Cheney, S. P.

1973-01-01

161

Pulses of chaos synchronization in coupled map chains with delayed transmission  

NASA Astrophysics Data System (ADS)

Pulses of synchronization in chaotic coupled map lattices are discussed in the context of transmission of information. Synchronization and desynchronization propagate along the chain with different velocities which are calculated analytically from the spectrum of convective Lyapunov exponents. Since the front of synchronization travels slower than the front of desynchronization, the maximal possible chain length for which information can be transmitted by modulating the first unit of the chain is bounded.

Schmitzer, Bernhard; Kinzel, Wolfgang; Kanter, Ido

2009-10-01

162

Calculations and experimental investigation of pulse transmission system in the typical module of the facility “Gamma”  

NASA Astrophysics Data System (ADS)

For the last few years in INRP RFNC-VNIIEF the works on development of a multi-module «Gamma» facility have been conducted. An important part of each module is a pulse transmission system (PTS), providing transportation of a high-volt electromagnetic pulse ( 2.3 MV, 60 ns) to a diode load, positioned at an angle of 80° to the axis of a module's forming system. Basic PTS units: a water-insulated transmission line (WTL), having a bended section, a vacuum insulator stack and a magnetically-insulated transmission line (MITL). At the first stage an experimental sample of PTS with diameter 0.65 m was studied. Performed studies allowed a conclusion that the given experimental PTS sample did not possess enough electric strength, what was a reason for electric breakdowns in the bended section of WTL. Reasons for breakdown occurrence were analyzed; conclusions were made on the necessity for increasing PTS diameter. As a result a PTS version with diameter 1 m was developed. This paper presents results of the experimental studies as a part of the facility module. Totally 200 shots of the module were performed with given PTS at different charge voltage of its forming lines. Reliable and steady operation of all PTS units, as well as correspondence between output module parameters and their calculated values were proved. When using PTS, without MITL in the module diode load, with impedance 3 Ohm the pulses with power 1.5 TW and total electron energy in a pulse 80 kJ were obtained. When using PTS with cylindrical MITL of 1.6 m length, the pulse power was 1.4 TW.

Zavyalov, N. V.; Punin, V. T.; Gordeev, V. S.; Grishin, A. V.; Nazarenko, S. T.; Balakin, V. A.; Glushkov, S. L.; Demanov, V. A.; Kozachek, A. V.; Pavlov, V. S.; Puchagin, S. Yu.; Strabykin, K. V.; Moiseevskikh, M. A.; Kalashnikov, D. A.; Spirin, D. P.; Mansurov, D. O.

2014-08-01

163

A long-pulse repetitive operation magnetically insulated transmission line oscillator  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

164

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

PubMed

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

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

2014-05-01

165

A long-pulse repetitive operation magnetically insulated transmission line oscillator  

SciTech Connect

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.

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

166

Investigations on optimizing the energy transmission of ultrafast optical pulses in pure water  

NASA Astrophysics Data System (ADS)

Many of today's communication and imaging technologies share the common challenge of signal deterioration due to water's large absorption coefficient. As an example, it is water molecules that contaminate the fused silica of optical fibers and account for most of the absorption they exhibit at communication wavelengths. It is also water (in the form of vapor) that makes it challenging to devise practical THz spectroscopic systems. As such, this thesis examines how the transmission of electromagnetic radiation through water could be improved as a stepping stone towards bettering a wide array of communication and imaging applications. Recent time-domain approaches have noted the connection between pulse rise-time and precursor waveform absorption. This thesis represents the first in-depth analysis of precursors using an intuitive frequency-domain approach. It was shown with well-known physical metrics that precursors are a linear effect resulting from the temporal representation of a Beer's law of absorption for broadband pulses. Experimental validation was achieved with a spatial light modulator used in conjunction with Frequency-Resolved-Optical-Gating (FROG) to obtain the first measurement of the amplitude and phase of an optical precursor. The semi-classical two-level atom model was used to infer the transitional dipole moments of the 1447 nm and 2:94 mum vibrational resonances of the medium. These values supported finite-difference-time-domain simulations suggesting how 52 fs sech2 pulses of 220 GW/cm2 peak intensity could propagate with negligible attenuation over 15 absorption lengths when tuned to the 2:94 mum transition of water. Extensive use of 1550 nm lasers in communication systems and the presence of the second vibrational overtone resonance of water at 1447 nm were the motivation for transmission experiments completed at the Naval Research Laboratory (Washington, DC) at this transition. As much as a 500% increase in absolute transmission was observed in a 5 mm sample of distilled water when compared to steady-state transmission. Different causes for this increase in transmission were examined, including coherent and incoherent bleaching effects. Overall, this study reveals that efficient propagation of optical pulses in water requires pulses of near single-cycle duration and large intensities and/or fluence. While these large intensities would make it difficult to apply this work to medical imaging applications, there remains a window of opportunity for efficient underwater communication. Indeed, assuming a channel of water with few physical obstructions, the advent of sufficiently intense, robust, and high repetition-rate laser technology might one day lead to the implementation of a practical underwater communication link at optical wavelengths.

Lukofsky, David

167

An investigation of pulse-timing techniques for broadband ultrasonic velocity determination in cancellous bone: a simulation study.  

PubMed

Berlage wavelets are used to simulate ultrasonic pulses in an unbounded, homogeneous, isotropic and absorptive medium. Intrinsic absorption of the medium is properly described by Kolsky's attenuation, which considers velocity dispersion to meet the causality condition. Several current time-domain velocity measurement techniques have been investigated using numerically simulated pulses for three normalized BUA values: 20, 40 and 60 dB MHz(-1) cm(-1), which mimic experimentally determined values for cancellous bone. The velocities, calculated using first motion transit times, are used as references supported by the Fermat principle of least time. The simulated results for fixed sample thickness indicate that pulse-broadening increases with the transit time of the reference point and the intrinsic absorption of the medium. Comparison shows that the first zero-crossing method yields 3-6% errors in velocity results, better than the cross-correlation method. However, the zero-crossing method gives inconsistent velocity measurement for a medium of 40 dB MHz(-1) cm(-1)1 absorption and three different thicknesses: 0.2, 0.4 and 0.6 cm. A novel technique for velocity measurement is presented using the peak of the envelope of a signal as a reference point to measure transit time difference. The envelope of a signal represents the instantaneous amplitude of the associated analytic signal. The velocities derived using this method differ from the true velocities by only 1.2-2.4%, more accurate than those obtained by the first zero-crossing method. The envelope peak has the additional merits of easy detection and robustness. Most importantly, the envelope technique may be used to yield accurate velocity measurement in cases where an accurate determination of the first motion transit time is sometimes prohibited due to the presence of noise. PMID:9725605

Le, L H

1998-08-01

168

Transmission line pulse system for avalanche characterization of high power semiconductor devices  

NASA Astrophysics Data System (ADS)

Because of the increasing in power density of electronic devices for medium and high power application, reliabilty of these devices is of great interest. Understanding the avalanche behaviour of a power device has become very important in these last years because it gives an indication of the maximum energy ratings which can be seen as an index of the device ruggedness. A good description of this behaviour is given by the static IV blocking characteristc. In order to avoid self heating, very relevant in high power devices, very short pulses of current have to be used, whose value can change from few milliamps up to tens of amps. The most used method to generate short pulses is the TLP (Transmission Line Pulse) test, which is based on charging the equivalent capacitance of a transmission line to high value of voltage and subsequently discharging it onto a load. This circuit let to obtain very short square pulses but it is mostly used for evaluate the ESD capability of semiconductor and, in this environment, it generates pulses of low amplitude which are not high enough to characterize the avalanche behaviour of high power devices . Advanced TLP circuit able to generate high current are usually very expensive and often suffer of distorption of the output pulse. In this article is proposed a simple, low cost circuit, based on a boosted-TLP configuration, which is capable to produce very square pulses of about one hundreds of nanosecond with amplitude up to some tens of amps. A prototype is implemented which can produce pulses up to 20A of amplitude with 200 ns of duration which can characterize power devices up to 1600V of breakdown voltage. Usage of microcontroller based logic make the circuit very flexible. Results of SPICE simulation are provided, together with experimental results. To prove the effectiveness of the circuit, the I-V blocking characteristics of two commercial devices, namely a 600V PowerMOS and a 1200V Trench-IGBT, are measured at different operating temperature.

Riccio, Michele; Ascione, Giovanni; De Falco, Giuseppe; Maresca, Luca; De Laurentis, Martina; Irace, Andrea; Breglio, Giovanni

2013-05-01

169

264 IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY, VOL. 1, NO. 1, SEPTEMBER 2011 Broadband THz Pulse Transmission  

E-print Network

264 IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY, VOL. 1, NO. 1, SEPTEMBER 2011 Broadband THz Pulse Transmission Through the Atmosphere Yihong Yang, Student Member, IEEE, Mahboubeh Mandehgar that experienced negligible attenuation and group velocity dispersion due to transmission through water vapor

Oklahoma State University

170

Energy-Resolving Neutron Transmission Radiography at the ISIS Pulsed Spallation Source With a High-Resolution Neutron Counting Detector  

Microsoft Academic Search

Neutron transmission radiography can be strongly enhanced by adding spectroscopic data spatially correlated with the attenuation coefficient. This can now be achieved at pulsed neutron sources, utilizing a neutron detector with high spatial and temporal resolution. The energy of transmitted neutrons can be recovered from their time-of-flight, simultaneously with the acquisition of the transmission radiographic image by a pixelated detector.

Anton S. Tremsin; Jason B. McPhate; Winfried A. Kockelmann; John V. Vallerga; Oswald H. W. Siegmund; W. Bruce Feller

2009-01-01

171

Energy-resolving neutron transmission radiography at the ISIS pulsed spallation source with a high-resolution neutron counting detector  

Microsoft Academic Search

Neutron transmission radiography can be strongly enhanced by adding spectroscopic data spatially correlated with the attenuation coefficient. This can now be achieved at pulsed neutron sources, utilizing a neutron detector with high spatial and temporal resolution. The energy of transmitted neutrons can be recovered from their time-of-flight, simultaneously with the acquisition of the transmission radiographic image by a pixilated detector.

Anton S. Tremsin; Jason B. McPhate; Winfried A. Kockelmann; John V. Vallerga; Oswald H. W. Siegmund; W. Bruce Feller

2008-01-01

172

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

NASA Astrophysics Data System (ADS)

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.

Faeth, Loren Elbert

173

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

174

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

175

Frequency division multiple transmission method to utilize the wide bandwidth property of capacitive micromachined ultrasonic transducer arrays  

NASA Astrophysics Data System (ADS)

CMUT-on-ASIC integration techniques are promising for the development of lower cost smaller volume scanners with higher performance in terms of features and image qualities because it minimizes parasitic capacitances and ultimately improves signal-to-noise ratio (SNR). Moreover, a frequency bandwidth of CMUT array is known as relatively broader than that of other ultrasonic transducer arrays. To utilize the wide bandwidth characteristic of the CMUT arrays, in this paper, we introduce a FDMA (frequency division multiple access) based ultrasound imaging technique using orthogonally band-divided coded signals to provide dynamic transmit focused imaging without sacrificing the frame rate. In the presented method, the orthogonal sub-band coded signals are simultaneously fired on multiple ranges, in which each signal is focused at a different range, in one transmission event. This paper also presents an ultrasound imageformation method and a modulation and demodulation process of orthogonal sub-band coded signals designed within the frequency bandwidth of the CMUT arrays. The presented method is verified by computer simulations using Field II and experiments. The simulation results using a computer generated tissue mimicking phantom show that the presented method can be achieved with both increased image quality and frame rate. The experimental results to verify the feasibility of the presented method using orthogonal sub-band coded signals show that the reflected signals from targets are successfully separated into two compressed signals. Currently, we are extending the presented approach to ultrasound imaging technique for volumetric ultrasound scanners using 2-D CMUT-on-ASIC arrays.

Lee, Seunghun; Kim, Bae-Hyung; Jeon, Taeho; Kim, Youngil; Cho, Kyungil; Song, Jongkeun

2013-03-01

176

10-MHz, Yb-fiber chirped-pulse amplifier system with large-scale transmission gratings.  

PubMed

Large-scale transmission gratings were produced for a stretcher and a compressor in the Yb-fiber chirped-pulse amplification system. A 23-W, 200-fs laser system with a 10-MHz repetition rate was demonstrated. Focused intensity as high as 10(14) W/cm(2) was achieved, which is high enough for multi-photon processes such as high-order harmonics generation and multi-photon ionization of neutral atoms. High-order harmonics up to 7th order were observed using Xe gas as a nonlinear medium. PMID:23736505

Kobayashi, Yohei; Hirayama, Nozomi; Ozawa, Akira; Sukegawa, Takashi; Seki, Takashi; Kuramoto, Yoshiyuki; Watanabe, Shuntaro

2013-05-20

177

The combined use of heat-pulse flowmeter logging and packer testing for transmissive fracture recognition  

NASA Astrophysics Data System (ADS)

This paper presents an improved borehole prospecting methodology based on a combination of techniques in the hydrogeological characterization of fractured rock aquifers. The approach is demonstrated by on-site tests carried out in the Hoshe Experimental Forest site and the Tailuge National Park, Taiwan. Borehole televiewer logs are used to obtain fracture location and distribution along boreholes. The heat-pulse flow meter log is used to measure vertical velocity flow profiles which can be analyzed to estimate fracture transmissivity and to indicate hydraulic connectivity between fractures. Double-packer hydraulic tests are performed to determine the rock mass transmissivity. The computer program FLASH is used to analyze the data from the flowmeter logs. The FLASH program is confirmed as a useful tool which quantitatively predicts the fracture transmissivity in comparison to the hydraulic properties obtained from packer tests. The location of conductive fractures and their transmissivity is identified, after which the preferential flow paths through the fracture network are precisely delineated from a cross-borehole test. The results provide robust confirmation of the use of combined flowmeter and packer methods in the characterization of fractured-rock aquifers, particularly in reference to the investigation of groundwater resource and contaminant transport dynamics.

Lo, Hung-Chieh; Chen, Po-Jui; Chou, Po-Yi; Hsu, Shih-Meng

2014-06-01

178

Ultrasonic meters measure gas pipeline flow  

SciTech Connect

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.

NONE

1995-04-01

179

The Next Linear Collider Test Accelerator's RF Pulse Compression And Transmission  

SciTech Connect

The overmoded rf transmission and pulsed power compression system for SLAC's Next Linear Collider (NLC) program requires a high degree of transmission efficiency and mode purity to be economically feasible. To this end, a number of new, high power components and systems have been developed at X-band, which transmit rf power in the low loss, circular TE01 mode with negligible mode conversion. In addition, a highly efficient SLED-II* pulse compressor has been developed and successfully tested at high power. The system produced a 200 MW, 250 ns wide pulse with a near-perfect flat-top. In this paper we describe the design and test results of the high power pulse compression system using SLED-II. The NLC rf systems use low loss highly over-moded circular waveguides operating in the TE01 mode. The efficiency of the systems is sensitive to the mode purity of the mode excited inside these guides. We used the so called flower petal mode transducer [2] to excite the TE01 mode. This type of mode transducer is efficient, compact and capable of handling high levels of power. To make more efficient systems, we modified this device by adding several mode selective chokes to act as mode purifiers. To manipulate the rf signals we used these modified mode converters to convert back and forth between over-moded circular waveguides and single-moded WR90 rectangular waveguides. Then, we used the relatively simple rectangular waveguide components to do the actual manipulation of rf signals. For example, two mode transducers and a mitered rectangular waveguide bend comprise a 90 degree bend. Also, a magic tee and four mode transducers would comprise a four-port-hybrid, etc. We will discuss the efficiency of an rf transport system based on the above methodology. We also used this methodology in building the SLEDII pulse compression system. At SLAC we built 4 of these pulse systems. In this paper we describe the SLEDII system and compare the performance of these 4 systems at SLAC. We report the experimental procedures used to measure their performance as well as the results of high power tests.

Tantawi, S.G.; Adelphson, C.; Holmes, S.; Lavine, Theodore L.; Loewen, R.J.; Nantista, C.; Pearson, C.; Pope, R.; Rifkin, J.; Ruth, R.D.; Vlieks, A.E.; /SLAC

2011-09-14

180

Ultrasonic measurement of elastic moduli in slender specimens using extensional and torsional wave pulses.  

NASA Technical Reports Server (NTRS)

The pulse-echo method using extensional and torsional waves is described relative to determining elastic properties and other characteristics of specimens which are slender acoustically. Several applications are reviewed, including: glass fibers of diameter 16 to 42 microns; glass rods of diameter about 1 mm, tested to 700 C; iron-base alloys of diameter 3.2 mm, tested from nearly -200 up to +200 C; titanium specimens of rectangular cross section, 1.5 by 3 mm; and tantalum-base alloys of diameter 6.4 mm, tested up to 1400 C. Limitations are pointed out regarding dispersive materials and geometry.

Lynnworth, L. C.

1973-01-01

181

A novel structure of transmission line pulse transformer with mutually coupled windings.  

PubMed

A novel structure of transmission line transformer (TLT) with mutually coupled windings is described in this paper. All transmission lines except the first stage of the transformer are wound on a common ferrite core for the TLT with this structure. A referral method was introduced to analyze the TLT with this structure, and an analytic expression of the step response was derived. It is shown that a TLT with this structure has a significantly slower droop rate than a TLT with other winding structures and the number of ferrite cores needed is largely reduced. A four-stage TLT with this structure was developed, whose input and output impedance were 4.2 ? and 67.7 ?, respectively. A frequency response test of the TLT was carried out. The test results showed that pulse response time of the TLT is several nanoseconds. The TLT described in this paper has the potential to be used as a rectangle pulse transformer with very fast response time. PMID:24689623

Yu, Binxiong; Su, Jiancang; Li, Rui; Zhao, Liang; Zhang, Xibo; Wang, Junjie

2014-03-01

182

Constant frequency pulsed phase-locked-loop instrument for measurement of ultrasonic velocity  

SciTech Connect

A new instrument based on a constant frequency pulsed phase-locked-loop (CFPPLL) concept has been developed to accurately measure the ultrasonicwavevelocity in liquids and changes in ultrasonicwavevelocity in solids and liquids. An analysis of the system shows that it is immune to many of the frequency-dependent effects that plague other techniques including the constant phase shifts of reflectors placed in the path of the ultrasonicwave.Measurements of the sound velocity in ultrapure water are used to confirm the analysis. The results are in excellent agreement with values from the literature, and establish that the CFPPLL provides a reliable, accurate way to measurevelocities, as well as for monitoring small changes in velocity without the sensitivity to frequency-dependent phase shifts common to other measurement systems. The estimated sensitivity to phase changes is better than a few parts in 10{sup 7}.

Yost, William T.; Cantrell, John H.; Kushnick, Peter W.

1991-10-01

183

Ultrasonic bone densitometer  

NASA Technical Reports Server (NTRS)

A device, for measuring the density of a bone structure so as to monitor the calcium content, is described. A pair of opposed spaced ultrasonic transducers are held within a clamping apparatus closely adjacent the bone being analyzed. These ultrasonic transducers incude piezoelectric crystals shaped to direct signals through the bone encompassed in the heel and finger of the subject being tested. A pulse generator is coupled to one of the transducers and generates an electric pulse for causing the transducers to generate an ultrasonic sound wave which is directed through the bone structure to the other transducer. An electric circuit, including an amplifier and a bandpass filter couples the signals from the receiver transducer back to the pulse generator for retriggering the pulse generator at a frequency proportional to the duration that the ultrasonic wave takes to travel through the bone structure being examined.

Hoop, J. M. (inventor)

1974-01-01

184

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

NASA Astrophysics Data System (ADS)

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.

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

2007-03-01

185

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

SciTech Connect

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.

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

186

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

SciTech Connect

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.

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

187

Magnetohydrodynamic Electromagnetic Pulse (MHD-EMP) interaction with power transmission and distribution systems  

NASA Astrophysics Data System (ADS)

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.

Tesche, F. M.; Barnes, P. R.; Meliopoulos, A. P. S.

1992-02-01

188

Laser ultrasonic TOFD method  

NASA Astrophysics Data System (ADS)

We applied laser ultrasound for the time of flight diffraction (TOFD) measurement. To find an effective testing condition of TOFD method, laser ultrasonic transmission around the slit in glass specimens was observed using the photoelastic ultrasonic visualization system. After the observation we constructed the laser TOFD system and applied to the slit depth measurement of aluminum plate, and then, obtained highly accurate results.

Mihara, T.; Ohtsuka, Y.; Cho, H.; Yamanaka, K.

2001-04-01

189

Laser ultrasonic TOFD method  

Microsoft Academic Search

We applied laser ultrasound for the time of flight diffraction (TOFD) measurement. To find an effective testing condition of TOFD method, laser ultrasonic transmission around the slit in glass specimens was observed using the photoelastic ultrasonic visualization system. After the observation we constructed the laser TOFD system and applied to the slit depth measurement of aluminum plate, and then, obtained

T. Mihara; Y. Ohtsuka; H. Cho; K. Yamanaka

2001-01-01

190

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

191

Ultrasonic pulse detection with split spectrum processing and consecutive polarity coincidence  

SciTech Connect

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.

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

1995-08-01

192

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

SciTech Connect

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.

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

193

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

SciTech Connect

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)

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

194

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)

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.

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

2014-04-01

195

Evaluation of Brillouin frequency shift and its temperature dependence in poly(pentafluorostyrene)-based polymer optical fibers by ultrasonic pulse-echo technique  

NASA Astrophysics Data System (ADS)

Poly(pentafluorostyrene) (PPFS), which can be easily synthesized and has a low optical loss window at 850 nm, is a promising alternative for a costly perfluorinated polymer as a base material of polymer optical fibers (POFs). To investigate the potential of a PPFS-POF as a Brillouin-based temperature sensing fiber, the Brillouin frequency shift and its temperature dependence of PPFS were estimated using an ultrasonic pulse-echo technique. The temperature coefficient, which determines the sensitivity of the temperature sensing, was approximately -7.1 MHz/K independently of the molecular weight and was nearly identical to that in perfluorinated POFs.

Minakawa, Kazunari; Koike, Kotaro; Hayashi, Neisei; Koike, Yasuhiro; Mizuno, Yosuke; Nakamura, Kentaro

2014-05-01

196

Evaluating the CDM-Robustness of the input buffer with very fast transmission line pulse  

NASA Astrophysics Data System (ADS)

In this paper, a scheme for how to utilize VFTLP (very fast transmission line pulse) data to design an input buffer circuit for CDM (charged-device model) ESD protection is reported. The impedance of the ESD device under VFTLP stress is nearly 120 ? at the beginning of turn-on transient, and decreases with time toward 10 ? prior to the voltage falling below 0 V. In this work, the fact that the dynamic-characteristic impedance of the ESD device under VFTLP testing is independent of the stress current is found. Since both VFTLP zapping and the CDM are nanosecond events, the dynamic-characteristic impedance of the ESD device can be used to evaluate the CDM threshold voltage of the input buffer based on the equivalent and simplified RLC circuit.

Kao, Tzu-Cheng; Lee, Jian-Hsing; Hung, Chung-Yu; Lien, Chen-Hsin; Su, Hung-Der

2015-02-01

197

Optical transmission control in graphene oxide and its organic composites with ultrashort laser pulses  

NASA Astrophysics Data System (ADS)

Nonlinear optical transmission of graphene oxide-(Cu, Zn, Sn, H2) porphyrin composites was investigated using the Z-scan technique at 532 nm with picosecond (ps) and 800 nm with femtosecond laser pulses. Pure porphyrins show saturable absorption (SA) in reverse saturable absorption (RSA) behaviour and graphene oxide shows complete RSA behaviour, observed in an open aperture Z-scan curve. Interestingly, composites have shown a switch-over from reverse RSA to SA and back to RSA behaviour, observed with variation of intensity towards the focus, due to strong two-photon absorption as well as excited state absorption in the ps regime. This switching behaviour was interpreted as due to long lifetimes and saturation of the excited states. This may find application in optical switching.

Krishna, M. Bala Murali; Venkatramaiah, N.; Narayana Rao, D.

2014-01-01

198

ELSEVIER Ultrasonics 35 (1997) 525-531 High-order spectra-based deconvolution of ultrasonic NDT  

E-print Network

ELSEVIER Ultrasonics 35 (1997) 525-531 High-order spectra-based deconvolution of ultrasonic NDTPetroleumund Mineruls, KFUPM Box 181 I, Dhahran 31261, Saudi Arabiu Received 14 April 1997 Abstract In ultrasonic of the measuring instruments, the propagation paths taken by the ultrasonic pulses, and noise. This measured pulse

Ghouti, Lahouari

199

Ultrasonic temperature measuring device  

NASA Technical Reports Server (NTRS)

Pulse echo ultrasonic system automatically determines the temperature in the core of a nuclear rocket engine by measuring the transit time of an acoustic pulse in a wire sensor. The measurement is based on the fact that the speed of sound in the sensor material is a function of temperature.

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

1968-01-01

200

Ultrasonic Monitor  

NASA Astrophysics Data System (ADS)

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.

1983-01-01

201

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

Microsoft Academic Search

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

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

202

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  

Microsoft Academic Search

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

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

2010-01-01

203

VOLUME 88, NUMBER 7 P H Y S I C A L R E V I E W L E T T E R S 18 FEBRUARY 2002 Boosting Sonoluminescence with a High-Intensity Ultrasonic Pulse Focused  

E-print Network

Sonoluminescence with a High-Intensity Ultrasonic Pulse Focused on the Bubble by an Adaptive Array Jean-bubble sonoluminescence is characterized by a great concentration of energy during the collapse of a gas bubble, which of sonoluminescence has limited previous attempts to reinforce this inertial confinement in order to generate photons

Forterre, Yoël

204

Ultrasonic Imaging of Reaction Wood in Standing Trees  

NASA Astrophysics Data System (ADS)

Wood is an orthotropic material and its properties depend on its age but also depend on environmental growing conditions. An important feature of property alteration is reaction wood formation. Reaction wood forms when part of a tree is subjected to mechanical stress, and helps to bring parts of the plant into an optimal position. This article aims to study the effect of reaction wood on ultrasonic wave propagation using tomographic imaging. The ultrasonic emission was a pulse train of square wave. The peak frequency was 80 kHz. Two logs of poplar and spruce were tested because of the presence of different types of reaction wood (tension wood for poplar and compression wood for spruce). Maps were computed according to the Radon theory and using a filtered back projection algorithm with fan beam geometry. The intrinsic parameters were the slowness (s/m) and attenuation (dB/m at 80 kHz). In addition to ultrasonic tests, X-ray imaging in transmission was used. The ultrasonic maps were analyzed to highlight the differences between normal wood and observed reaction zones. The X-ray images were also compared to ultrasonic maps and the relationships between X-ray attenuation and ultrasonic parameters were discussed.

Brancheriau, Loic; Saadat-Nia, Mohammad Ali; Gallet, Philippe; Lasaygues, Philippe; Pourtahmasi, Kambiz; Kaftandjian, Valerie

205

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

SciTech Connect

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.

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

2009-05-04

206

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 Central

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

Lau, Hwee Wen; Nyam, Kar Lin

2014-01-01

207

Axial transmission method for long bone fracture evaluation by ultrasonic guided waves: simulation, phantom and in vitro experiments.  

PubMed

Mode conversion occurs when the ultrasonic guided waves encounter fractures. The aim of this study was to investigate the feasibility of fracture assessment in long cortical bone using guided-mode conversion. Mode conversion behavior between the fundamental modes S0 and A0 was analyzed. The expressions proposed for modal velocity were used to identify the original and converted modes. Simulations and phantom experiments were performed using 1.0-mm-thick steel plates with a notch width of 0.5 mm and notch depths of 0.2, 0.4, 0.6 and 0.8 mm. Furthermore, in vitro experiments were carried out on nine ovine tibias with 1.0-mm-wide partial transverse gap break and cortical thickness varying from 2.10 to 3.88 mm. The study confirmed that mode conversion gradually becomes observable as fracture depth increases. Energy percentages of the converted modes correlated strongly with fracture depth, as illustrated by the frequency-sweeping experiments on steel phantoms (100-1100 kHz, r(2) = 0.97, p < 0.0069) and the fixed-frequency experiments on nine ovine tibias (250 kHz, r(2) = 0.97, p < 0.0056). The approaches described, including mode excitation, velocity expressions and energy percentage criteria, may also contribute to ultrasonic monitoring of long bone fracture healing. PMID:24433749

Xu, Kailiang; Ta, Dean; He, Runxin; Qin, Yi-Xian; Wang, Weiqi

2014-04-01

208

Ultrasonic determination of recrystallization  

NASA Technical Reports Server (NTRS)

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.

Generazio, E. R.

1986-01-01

209

Pulse  

MedlinePLUS

... the pulse rate can help determine if the patient's heart is pumping. Pulse measurement has other uses as well. During or immediately after exercise, the pulse rate gives information about your fitness ...

210

Accelerated Multi-Dimensional RF Pulse Design for Parallel Transmission Using Concurrent Computation on Multiple Graphics Processing Units  

PubMed Central

Multi-dimensional RF pulses are of current interest due to their promise for improving high field imaging as well as for optimizing parallel transmission methods. One major drawback is that the computation time of numerically designed multi-dimensional RF pulses increases rapidly with their resolution and number of transmitters. This is critical because the construction of multi-dimensional RF pulses often needs to be in real time. The use of graphics processing units for computations is a recent approach for accelerating image reconstruction applications. We propose the use of graphics processing units for the design of multi-dimensional RF pulses including the utilization of parallel transmitters. Using a desktop computer with four NVIDIA Tesla C1060 computing processors, we found acceleration factors on the order of twenty for standard eight-transmitter 2D spiral RF pulses with a 64 × 64 excitation resolution and a ten-microsecond dwell time. We also show that even greater acceleration factors can be achieved for more complex RF pulses. PMID:21264929

Deng, Weiran; Yang, Cungeng; Stenger, V. Andrew

2010-01-01

211

Transmission of laser pulses with high output beam quality using step-index fibers having large cladding  

SciTech Connect

An apparatus and method for transmission of laser pulses with high output beam quality using large core step-index silica optical fibers having thick cladding, are described. The thick cladding suppresses diffusion of modal power to higher order modes at the core-cladding interface, thereby enabling higher beam quality, M.sup.2, than are observed for large core, thin cladding optical fibers. For a given NA and core size, the thicker the cladding, the better the output beam quality. Mode coupling coefficients, D, has been found to scale approximately as the inverse square of the cladding dimension and the inverse square root of the wavelength. Output from a 2 m long silica optical fiber having a 100 .mu.m core and a 660 .mu.m cladding was found to be close to single mode, with an M.sup.2=1.6. Another thick cladding fiber (400 .mu.m core and 720 .mu.m clad) was used to transmit 1064 nm pulses of nanosecond duration with high beam quality to form gas sparks at the focused output (focused intensity of >100 GW/cm.sup.2), wherein the energy in the core was <6 mJ, and the duration of the laser pulses was about 6 ns. Extending the pulse duration provided the ability to increase the delivered pulse energy (>20 mJ delivered for 50 ns pulses) without damaging the silica fiber.

Yalin, Azer P; Joshi, Sachin

2014-06-03

212

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

NASA Astrophysics Data System (ADS)

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.

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

213

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  

SciTech Connect

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.

Sakai, Y.; Takahashi, S.; Watanabe, M.; Hotta, E. [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midoriku, Yokohama, Kanagawa 226-8502 (Japan); Kim, G.-H. [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

2010-04-15

214

Detection of laser-induced nanosecond ultrasonic pulses in metals using a pancake coil and a piezoelectric sensor  

Microsoft Academic Search

A piezoelectric sensor and a pancake coil sensor were used for broadband detection of laser-induced ultrasound in single-crystal aluminum and polycrystalline nickel. Pressure pulses with pronounced compression phases were induced by laser pulses of 5 ns duration from one side of the specimens and detected from the opposite side. A coupling layer of water was required for the piezoelectric method,

Victor V. Kozhushko; Heinz Krenn

2012-01-01

215

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

SciTech Connect

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.

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

2005-06-01

216

Ultrasonic evaluation of high voltage circuit boards  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

217

Transmission of THz pulse with a few circles through opaque samples placed at long distance (4-6 metres)  

NASA Astrophysics Data System (ADS)

Nowadays, the detection and identification of dangerous substances at long distance (several metres, for example) by using of THz pulse reflected from the object is an important problem. The main problem with this technique is the absorption of THz energy by water vapor. However, using THz pulsed radiation is possible at distance of some metres as it is well-known. Below we demonstrate possibility of THz signal measuring reflected from a flat metallic mirror placed about 4 metres from the parabolic mirror. Investigated object is placed before this mirror. Therefore, at present time our measurements contain features of both transmission and reflection modes. The reflecting mirror is used because of weak averaged power of femtosecond laser. This power is about 1 W. Moreover, the laser beam splits many times. Therefore, the averaged power falling on the THz emitter decreases at least 8 times. The pulse duration generated by the femtosecond laser is equal to 68 fs. Measurements were provided at room temperature and humidity about 70%. The aim of investigation was the detection of a substance in real conditions. We discuss new features of the detection of a substance covered under various ordinary materials and possible way for their influence deleting on the detection using reflected THz pulse. We discuss also details of action of THz pulse with a few circles on media. The main feature of such interaction is its dependence from absolute phase of the THz pulse. We demonstrate results of computer simulations as well as physical experiment results for propagation of such laser pulses.

Trofimov, Vyacheslav A.; Varentsova, Svetlana A.; Trofimov, Vladislav V.

2014-09-01

218

Ultrasonic characterization of materials by means of under water Laser Doppler Vibrometer measurements of continuous waves  

NASA Astrophysics Data System (ADS)

Pulse signals are widely use for several ultrasonic testing. They indeed allow an easy estimation of the delays occurring in echo and transmission measurements and give the possibility to filter the noise (i.e undesired reflections occurring in the surface of the transducers) applying a window in the time domain. However their high crest factor makes these signals unsuitable to test attenuating materials. For this reason this paper proposes a new method, based on continuous waves, for ultrasonic characterization of materials. A a wave propagation model in the frequency domain is presented, to determine simultaneously acoustic velocity, mass density, and thickness of two Plexiglas plates, during transmission experiments. The Ultrasonic waves are captured by a Scanning Laser Doppler Vibrometer (SLDV) in order to guarantee a large number of spatial points, acquired with a high resolution.

Longo, Roberto; Steenackers, Gunther; Vanlanduit, Steve; Guillaume, Patrick

2010-05-01

219

Ultrasonic Wave Generation by Lasers on Different Metal Surfaces  

Microsoft Academic Search

Ultrasonic wave generation by short pulsed laser is revisited in this paper with new experimental work. The generation laser pulse is fiber delivered and a virtually uniform intensity spot is obtained. Ultrasonic pulse strength versus laser pulse energy is obtained for various aluminum and steel surface conditions. To have a better reproducibility, the sample moves after each measurement in order

S. E. Kruger; M. Lord

2007-01-01

220

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

NASA Astrophysics Data System (ADS)

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.

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

2012-01-01

221

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

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 ...

Chen, Kailiang

222

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

NASA Astrophysics Data System (ADS)

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.

Homma, Akira

2011-07-01

223

Transmission  

Microsoft Academic Search

A transmission is described which consists of: an input shaft; an output shaft; a first planetary gear set including a first sun gear selectively connectable by a first clutch to the input shaft, a first carrier selectively connectable by a second clutch to the input shaft and a first ring gear connected to the output shaft. The first sun gear

Sugano

1988-01-01

224

Ultrasonic crack diffraction in metals using laser-generated ultrasonic shear waves and broadband EMAT detection  

Microsoft Academic Search

Understanding the nature of ultrasonic propagation, scattering effects and mode conversation for crack diffraction in materials is critical to the effectiveness of ultrasonic characterization and sizing cracks and defects in structures. Thus far, a complete solution for the diffraction of an ultrasonic pulse of arbitrary shape at a crack of arbitrary shape has not yet been achieved. In this work,

J. R. Bernstein; J. B. Spicer

2000-01-01

225

Ultrasonic crack diffraction in metals: Investigations using laser generated ultrasonic shear waves and broadband EMAT detection  

Microsoft Academic Search

Understanding the nature of ultrasonic propagation, scattering effects and mode conversion for crack diffraction in materials is critical to the effectiveness of ultrasonic characterization methods. This is especially important for the application of characterizing and sizing cracks and defects in structures. Thus far, a complete solution for the diffraction of an ultrasonic pulse of arbitrary shape at a crack of

Johanna Rebecca Bernstein

1999-01-01

226

The Effect of Channel Errors in the Differential Pulse-Code-Modulation Transmission of Sampled Imagery  

Microsoft Academic Search

This paper presents an analysis, simulation, and discussion of the effects of communication errors on four-bit differential pulse-code modulation (DPCM) sampled imagery. Simulations are presented that describe the effects of inserting periodic \\

R. Arguello; H. Sellner; J. Stuller

1971-01-01

227

Anomalous transmission of high contrast relativistically intense short pulses through thin metal foils  

Microsoft Academic Search

The frequency doubled laser pulses from the T3 laser system at the Center for Ultrafast Optical Science of the University Michigan1 (with energy up to 1 J, a pulse duration of 400 fs, the wavelength is 0.53 mu m and the maximum intensity is 2.7× 1019 W\\/cm2) has been used to measure the light transmitted through thin metal targets. The

T. Matsuoka; A. Maksimchuk; T. Lin; O. V. Batishchev; A. A. Batishcheva; V. Yu. Bychenkov

2006-01-01

228

Anomalous Transmission of High Contrast Relativistically Intense Short Laser Pulses through Thin Metal Foils  

Microsoft Academic Search

The frequency doubled laser pulses from the T^3 laser system at the Center for Ultrafast Optical Science of the University Michigan (with energy up to 1 J, a pulse duration of 400 fs, the wavelength is 0.53 mum and the maximum intensity is 10^19 W\\/cm^2) has been used for the measurement of the light transmitted through thin metal targets. The

T. Matsuoka; O. V. Batishchev; A. A. Batishcheva; V. Yu. Bychenkov

2005-01-01

229

Resolution of scanning ultrasonic imaging systems with arbitrary transducer excitation  

E-print Network

383 Resolution of scanning ultrasonic imaging systems with arbitrary transducer excitation M pulses, the same considerations might be needed in analysing optical focussing systems. point spread functions for each component in the frequency spectrum. In medical ultrasonics and in systems

Paris-Sud XI, Université de

230

A high-performance ultrasonic system for the simultaneous transmission of data and power through solid metal barriers.  

PubMed

This paper presents a system capable of simultaneous high-power and high-data-rate transmission through solid metal barriers using ultrasound. By coaxially aligning a pair of piezoelectric transducers on opposite sides of a metal wall and acoustically coupling them to the barrier, an acoustic- electric transmission channel is formed which prevents the need for physical penetration. Independent data and power channels are utilized, but they are only separated by 25.4 mm to reduce the system's form factor. Commercial off-the-shelf components and evaluation boards are used to create realtime prototype hardware and the full system is capable of transmitting data at 17.37 Mbps and delivering 50 W of power through a 63.5-mm thick steel wall. A synchronous multi-carrier communication scheme (OFDM) is used to achieve a very high spectral efficiency and to ensure that there is only minor interference between the power and data channels. Also presented is a discussion of potential enhancements that could be made to greatly improve the power and data-rate capabilities of the system. This system could have a tremendous impact on improving safety and preserving structural integrity in many military applications (submarines, surface ships, unmanned undersea vehicles, armored vehicles, planes, etc.) as well as in a wide range of commercial, industrial, and nuclear systems. PMID:23287924

Lawry, Tristan J; Wilt, Kyle R; Ashdown, Jon D; Scarton, Henry A; Saulnier, Gary J

2013-01-01

231

Application of a digital non-linear compensation algorithm for evaluating the performance of root-raised-cosine pulses in 112 Gbit s-1 DP-QPSK transmission  

NASA Astrophysics Data System (ADS)

In this paper, we numerically investigate the non-linear tolerance of root-raised-cosine (RRC) pulse shaping by interpolating finite impulse response (FIR) filters in conjunction with digital backward propagation (DBP) in coherent 112 Gbit s-1 dual-polarization quadrature phase shift keying (DP-QPSK) transmission. The results depict that RRC pulses are more tolerant to intra-channel non-linearities, i.e. self-phase modulation (SPM), as compared to standard RZ-33 and NRZ pulses. The non-linear threshold point is improved by using RRC pulses by a factor of 2 dB signal input power as compared to RZ pulses and by 4 dB signal launch power as compared to NRZ pulses. The behavior of RRC pulses is also investigated with standard single mode fiber (SMF), non-zero dispersion shifted fiber (NZDSF) and next-generation large Aeff pure silica core fiber (LA-PSCF). Most importantly multi-span DBP is implemented and in the case of RRC pulses the computational efforts of the conventional DBP algorithm are reduced by 80% with a diminutive Q-penalty of 0.74 dB. The duty cycle of the RRC pulses is further optimized for efficient system performance. We have also compared the performance of single-channel transmission with the multi-channel transmission, where the performance is limited due to inter-channel non-linear effects. Furthermore, the non-linear tolerance of RRC pulses is investigated with; (a) different amplifier spacing and (b) variation in transmission link design information for the DBP algorithm.

Asif, Rameez; Usman, Muhammad; Lin, Chien-Yu; Schmauss, Bernhard

2012-09-01

232

Ultrasonic monitoring of material processing using clad buffer rod sensors  

NASA Astrophysics Data System (ADS)

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.

Ramos Franca, Demartonne

233

Improvement of ultrasonic characteristics in butt-welded joint of austenitic stainless steel using magnetic stirring method  

SciTech Connect

Magnetic Stirring Method of Tungsten Inert Gas(TIG) Welding are applied to butt-welded joint of austenitic stainless steel. The purpose of this method is to refine the welded structure and to improve the ultrasonic characteristics. In the conventional method of ultrasonic test in austenitic stainless steel weldments, dendritic solidification structure of weldment prevents smooth ultrasonic beam transmission. The tests are performed in three welding conditions; One is conventional TIG welding (without magnetic stirring), the other two are TIG welding using magnetic stirring method. Each test piece is evaluated by observing macro structure of cross section and by several ultrasonic tests examining pulse amplitudes, beam path length and proceeding beam direction. The detectability of artificial notches in weldment is also investigated and compared.

Tanosaki, M.; Yoshikawa, K.; Arakawa, T. [Ishikawajima-Harima Heavy Industries Co., Ltd., Yokohama (Japan)

1995-08-01

234

Estimation and correction of ultrasonic wavefront distortion using pulse-echo data received in a two-dimensional aperture  

Microsoft Academic Search

Pulse-echo measurements from random scattering and from a point target have been used to quantify transmitter beam size effects and isoplanatic patch size as well as to evaluate the performance of different aberration compensation techniques. Measurements were made using a single-element transmitter with a diameter of 1\\/2 in., 1 in., or 2 in., each focused at 3 in. A tissue-mimicking

D.-L. D. Liu; Robert C. Waag

1998-01-01

235

How to check line channel of IKM-15 digital pulse-code-modulation transmission system  

Microsoft Academic Search

A generator of test signals is developed for checking the line channel of a digital pulse code modulation apparatus in rural telephone networks. The test signal generator consists of a relative group reference generator, a pseudorandom sequence generator and an output amplifier. The test signal generator for checking either a terminal station or an intermediate station of a line channel

G. A. Abramov; M. M. Ptichnikov; Y. P. Savchenkov

1984-01-01

236

Noise immunity of data transmission systems with delta modulation and differential pulse code modulation  

Microsoft Academic Search

A model of a memoryless binary symmetric channel for delta modulation is used to obtain a conditional distribution of errors in the sample caused by distortions in the communication channel. An algorithm for determining the conditional error distribution is proposed for differential pulse code modulation.

N. I. Pilipchuk

1982-01-01

237

An E-plane EBG waveguide for dispersion compensated transmission of short pulses  

Microsoft Academic Search

The resolution of radar applications can significantly suffer from pulse broadening along the propagation in homogeneous hollow waveguides. The latter occurs due to the strongly dispersive nature of the fast waves in the waveguides. A low-cost solution to this problem is here proposed, employing an EBG type of waveguide, compatible with traditional E-plane fabrication techniques. By means of an example,

G. Goussetis; N. Uzunoglou; J.-L. Gomez-Tornero; B. Gimeno; V. E. Boria

2007-01-01

238

Evaluation of the phase correlation between the optical pulses for transmission in quantum key distribution  

NASA Astrophysics Data System (ADS)

One of the key assumptions in the security proof of BB84 quantum key distribution (QKD) protocol with a weak coherent light source is that the phase of each pulse emitted from the source is random. If the phases correlated, an efficient eavesdropping method exists, and more sacrifice bits are necessary to guarantee the security of the protocol. The phase correlation between the adjacent pulses was examined experimentally, for the first time, by measuring the visibility of interference. An asymmetric Mach-Zehnder interferometer was used to observe the interference between adjacent pulses from a distributed feedback (DFB) laser diode driven by 10 GHz clock signal. Clear interference was observed when the DC bias current exceeds the laser threshold. This high visibility implies phase correlation between pulses. In contrast, only a low visibility, i.e. very weak phase correlation, was observed when the DC bias current was set far below the threshold. The phase correlation became stronger as the DC bias current increased. The experimental results imply that a QKD equipment implementing BB84 protocol with a coherent light source is secure as long as the laser is operated in gain-switch even for 10 GHz clock frequency.

Kobayashi, Toshiya; Tomita, Akihisa; Okamoto, Atsushi

2014-02-01

239

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

NASA Astrophysics Data System (ADS)

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.

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

2002-11-01

240

Transmission  

SciTech Connect

A transmission is described which consists of: an input shaft; an output shaft; a first planetary gear set including a first sun gear selectively connectable by a first clutch to the input shaft, a first carrier selectively connectable by a second clutch to the input shaft and a first ring gear connected to the output shaft. The first sun gear selectively held stationary by a first brake, the first carrier is allowed to rotate in the same forward direction as the input shaft when the second clutch is engaged, but prevented from rotating in a reverse direction opposite to the forward direction by a first one-way clutch, the first carrier being selectively held stationary by a second brake; a second planetary gear set including a second sun gear connected to the input shaft, a second carrier connected to the first ring gear and also the the output shaft, and a second ring gear.

Sugano, K.

1988-12-27

241

Low-latency photonic network using ultrashort-pulse transmissions and time-domain processing  

Microsoft Academic Search

This paper describes a family of interconnect system based on optical time division multiplexing (OTDM) for use as system area networks (SAN). The low latency and high bisection bandwidth that is attainable with this type of systems is ideally suited for scalable multiprocessor applications. The ability to rapidly switch transmission channels of these OTDM system gives them the logical appearance

Andreas G. Nowatzyk

1998-01-01

242

On pulse vaccination strategy in the SIR epidemic model with vertical transmission  

Microsoft Academic Search

The aim of this short paper is to improve a result recently given by Lu et al. on the global asymptotic stability of the eradication solution of the PVS applied to diseases with vertical transmission, by demonstrating that the condition for local stability guarantees also the global stability.

Alberto d’Onofrio

2005-01-01

243

Ultrasonic Imaging Of Deep Arteries  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

244

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

PubMed Central

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

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

2014-01-01

245

Transmission line pulse properties for a bidirectional transient voltage suppression diode fabricated using low-temperature epitaxy  

NASA Astrophysics Data System (ADS)

Based on low temperature epitaxy technology, a bidirectional transient voltage suppression (TVS) diode with abrupt multi-junctions was developed. The bidirectional triggering voltage of ±16 V was controlled by the thickness and dopant concentration in the multi-junctions using a reduced-pressure chemical vapor deposition (RPCVD) process. The manufactured TVS diode showed a small leakage current density and dynamic resistance of less than 5.1 × 10-14 A/ µm2 and 1 O, respectively, which could be associated with the epitaxially grown abrupt multijunctions. The transmission line pulse (TLP) analysis results demonstrated that the bidirectional TVS diodes were capable of withstanding a peak pulse current of up to ±20 A or ±1.02 × 10-3 A/ µm2, which is equivalent to ±40 kV of the human body model (HBM) and ±12 kV of IEC61000-4-2 (IEC). Nevertheless, the electrostatic discharge (ESD) design window showed that bidirectional TVS diodes meet IEC level 4 standard ESD protection requirements (8 kV in contact discharge). In addition, because of the bidirectional structure, the TVS devices exhibited a small capacitance of 4.9 pF, which confirms that the TVS diode can be used for protecting high data rate communication lines (over 500 Mbps) from ESD shock.

Bouangeune, Daoheung; Cho, Deok-Ho; Yun, Hyung-Joong; Shim, Kyu-Hwan; Choi, Chel-Jong

2015-01-01

246

Bragg-edge transmission imaging of strain and microstructure using a pulsed neutron source  

NASA Astrophysics Data System (ADS)

The residual strain and the total cross-section in Fe plate was investigated by a Bragg-edge transmission method. The experiments were performed at the position of the time-of-flight diffractometer at KENS, Sirius. The (? d/ d) reached about 0.1%. The high counting rate and high efficiency pixel type 2d-detector with 8×8 pixels was used. The spatial resolution is about 2.1 mm. We clearly observed the image of the change on Bragg-edge shapes and the strain distribution. The total cross-section around the bending points was larger than other areas but there was no change in the Bragg-edge positions, which would correspond to the change of the microstructure. We obtained the image of residual strain at several points. The values of the residual strain at several lattice planes, ?110, ?200 and ?211, are -263 to 1707 ??, -612 to 1665 ?? and -1205 to 327 ??, respectively. It is indicated that the residual strain measurement by the Bragg-edge transmission is not inferior to the high-resolution Bragg diffraction.

Iwase, K.; Sakuma, K.; Kamiyama, T.; Kiyanagi, Y.

2009-06-01

247

Ultrasonic absortion in fatigued materials  

NASA Astrophysics Data System (ADS)

Non-destructive detection of fatigue damage, allowing an estimate of the residual life-time of components, could contribute to a safe and reliable operation of components and installations. Ultrasonic absorption, i.e. the internal friction, of a material increases with increasing fatigue or creep damage and there are many theories trying to explain the physics behind this phenomenon. Measurement of ultrasonic absorption directly on components could provide information on the degree of damage. A laser ultrasonic method, using laser-generated pulses and optical detection, was applied to study ultrasonic absorption in fatigue specimens of different metals. A characteristic behavior of the ultrasonic absorption coefficient with increasing levels of fatigue damage was found for the titanium alloy Ti-6Al-4V. Another aim of this study was to relate the absorption mechanisms to the behavior of ultrasonic absorption observed in metals with complex microstructure. To achieve this, different ultrasonic absorption mechanisms were analyzed with respect to experimental data. A thermoelastic effect related to the size and elasticity of the microstructure is discussed as the origin of the increased ultrasonic absorption.

Dugan, S.; Arnold, W.

2013-01-01

248

Surface micromachined capacitive ultrasonic transducers  

Microsoft Academic Search

The current state of novel technology, surface microfabricated ultrasonic transducers, is reported. Experiments demonstrating both air and water transmission are presented. Air-coupled longitudinal wave transmission through aluminum is demonstrated, implying a 110 dB dynamic range for transducers at 2.3 MHz in air. Water transmission experiments from 1 to 20 MHz are performed, with a measured 60 dB SNR at 3

Igal Ladabaum; Xuecheng Jin; Hyongsok T. Soh; Abdullah Atalar; Butrus T. Khuri-Yakub

1998-01-01

249

Wire Crimp Connectors Verification using Ultrasonic Inspection  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

250

INSTANTANEOUS DAMAGE IDENTIFICATION AND LOCALIZATION THROUGH SPARSE LASER ULTRASONIC SCANNING  

E-print Network

INSTANTANEOUS DAMAGE IDENTIFICATION AND LOCALIZATION THROUGH SPARSE LASER ULTRASONIC SCANNING ultrasonic scanning. First, an inspection path is selected from an intended inspection region of a target structure. Then, ultrasonic waves are generated at one endpoint A of the path with a pulse laser

Paris-Sud XI, Université de

251

Ultrasonic Imaging of Immersed Objects using Migration Tomas Olofsson  

E-print Network

The synthetic aperture focusing technique (SAFT) is often used for imaging in non-destructive ultrasonic testing ultrasonic immersion tests. 1 Introduction Non-destructive testing (NDT) using pulse-echo data have much be successfully applied to data from ultrasonic immersion tests. The paper starts by noting some differences

252

Ultrasonic modeling for complex geometries and materials  

NASA Astrophysics Data System (ADS)

This work considers ultrasonic wave propagation in complex geometries and materials and the scattering of various types of flaws. Multi-Gaussian beam models are developed where the wave field of an ultrasonic transducer is simulated by the superposition of a few Gaussian beams. It is shown that the propagation and transmission/reflection of a Gaussian beam in both isotropic and anisotropic media with multiple curved interfaces can be compactly written in terms of A, B, C, D matrices that can then be multiplied together to determine the properties of the Gaussian beam. For anisotropic media, the Gaussian beam model is quite complex since it also depends on the slopes and curvatures of the slowness surface. It is demonstrated that this complexity can be considerably reduced through the use of slowness coordinates and that there is a new and efficient way to determine the slowness surface curvature terms. A number of simulation examples for both isotropic and anisotropic media demonstrate that multi-Gaussian beam models based on these formulations are both very versatile and efficient. Ultrasonic flaw scattering problems are solved in this work by use of the Kirchhoff and Born approximations. Through comparison with more exact scattering models it is shown that the Kirchhoff approximation for the pulse-echo response of both spherical voids and planar cracks in isotropic solids is valid over a much wider range of frequencies and angles normally assumed for this approximation provided the bandwidth of the ultrasonic system is sufficiently large. Using the Kirchhoff approximation a new analytical expression is obtained for the pulse-echo leading edge response of a volumetric flaw in a general anisotropic medium and for the response of an elliptical flat crack in a general anisotropic medium. The Born approximation has also been considered in this work. A new modified Born approximation is developed that substantially improves the ability of that approximation to predict the pulse-echo amplitude response of both strong and weak scattering inclusions in an isotropic solid. It is also shown that the form of this modified Born approximation remains valid for anisotropic media as well.

Huang, Ruiju

253

Flight tests of a digital data acquisition system for analysis of ultrasonic pulse-echo signals used to measure ice accretion  

E-print Network

A number of signal processing algorithms were developed for analyzing ultrasonic signals used to measure aircraft ice accretion in flight. A high speed digital signal acquisition system was designed and constructed to ...

Ryan, Justin Mark

1986-01-01

254

Using Pulse Width Modulation for Wireless Transmission of Neural Signals in Multichannel Neural Recording Systems  

PubMed Central

We have used a well-known technique in wireless communication, pulse width modulation (PWM) of time division multiplexed (TDM) signals, within the architecture of a novel wireless integrated neural recording (WINeR) system. We have evaluated the performance of the PWM-based architecture and indicated its accuracy and potential sources of error through detailed theoretical analysis, simulations, and measurements on a setup consisting of a 15-channel WINeR prototype as the transmitter and two types of receivers; an Agilent 89600 vector signal analyzer and a custom wideband receiver, with 36 and 75 MHz of maximum bandwidth, respectively. Furthermore, we present simulation results from a realistic MATLAB-Simulink model of the entire WINeR system to observe the system behavior in response to changes in various parameters. We have concluded that the 15-ch WINeR prototype, which is fabricated in a 0.5-?m standard CMOS process and consumes 4.5 mW from ±1.5 V supplies, can acquire and wirelessly transmit up to 320 k-samples/s to a 75-MHz receiver with 8.4 bits of resolution, which is equivalent to a wireless data rate of ~ 2.26 Mb/s. PMID:19497823

Yin, Ming; Ghovanloo, Maysam

2013-01-01

255

Real time adaptive parametric equalization of Ultrasonic Transducers  

Microsoft Academic Search

Parametric equalization is often used to achieve a desired response from an audio transmitter, but is rarely applied to ultrasonic transducer systems. The ability of a broadband ultrasonic transmission and reception system to adapt its frequency and time domain response to changing acoustic conditions would be a distinct advantage in certain applications. Ultrasonic remote monitoring systems would benefit significantly from

S. G. McSweeney; William M. D. Wright

2009-01-01

256

Ultrasonic monitoring of materials during extrusion manufacture  

Microsoft Academic Search

In this paper we present a new method to monitor polymeric materials as they are being extruded. The ultrasonic technique makes use of both thru-transmission and backscattered signals from sensors that do not contact the extrusion. A novel aspect of the approach is the use of the liquid inherent within the heated polymer to provide coupling of the ultrasonic waves.

W. N. Cobb; J. J. Johnson

2001-01-01

257

A 13.56-mbps pulse delay modulation based transceiver for simultaneous near-field data and power transmission.  

PubMed

A fully-integrated near-field wireless transceiver has been presented for simultaneous data and power transmission across inductive links, which operates based on pulse delay modulation (PDM) technique. PDM is a low-power carrier-less modulation scheme that offers wide bandwidth along with robustness against strong power carrier interference, which makes it suitable for implantable neuroprosthetic devices, such as retinal implants. To transmit each bit, a pattern of narrow pulses are generated at the same frequency of the power carrier across the transmitter (Tx) data coil with specific time delays to initiate decaying ringing across the tuned receiver (Rx) data coil. This ringing shifts the zero-crossing times of the undesired power carrier interference on the Rx data coil, resulting in a phase shift between the signals across Rx power and data coils, from which the data bit stream can be recovered. A PDM transceiver prototype was fabricated in a 0.35- ?m standard CMOS process, occupying 1.6 mm(2). The transceiver achieved a measured 13.56 Mbps data rate with a raw bit error rate (BER) of 4.3×10(-7) at 10 mm distance between figure-8 data coils, despite a signal-to-interference ratio (SIR) of -18.5 dB across the Rx data coil. At the same time, a class-D power amplifier, operating at 13.56 MHz, delivered 42 mW of regulated power across a separate pair of high-Q power coils, aligned with the data coils. The PDM data Tx and Rx power consumptions were 960 pJ/bit and 162 pJ/bit, respectively, at 1.8 V supply voltage. PMID:24760945

Kiani, Mehdi; Ghovanloo, Maysam

2015-02-01

258

Segmented Motion Compensation for Complementary Coded Ultrasonic Imaging   

E-print Network

Ultrasonic imaging using complementary coded pulses offers the SNR improvements of signal coding without the filter side-lobes introduced by single-transmit codes. Tissue motion between coded pulse emissions, however, can introduce high side...

Cannon, Cormac; Hannah, John; McLaughlin, Steve

259

Improvement of ultrasonic testing of concrete by combining signal conditioning methods, scanning laser vibrometer and space averaging techniques  

Microsoft Academic Search

This paper deals with the combination of several techniques to improve the ultrasonic pulse echo testing of concrete elements when a laser doppler interferometer is used as the ultrasonic receiver. This techniques involves specially designed ultrasonic probes, a pulse compression technique, random speckle modulation and space time signal processing methods. The pulse echo technique is carried out by sending frequency

B. Koehler; G. Hentges; W. Mueller

1998-01-01

260

Sparse deconvolution of ultrasonic NDE traces—a preliminary study  

Microsoft Academic Search

The paper deals with the problem of deconvolving sparse ultrasonic NDE traces with time-varying pulses. A sparse dictionary learning algorithm is utilized to learn a time-varying pulse matrix. Each element of the matrix represents an individual pattern of possible local impulse responses. An ultrasonic signal is then decomposed into a sparse representation by the sparse Bayesian learning algorithm over the

Guang-Ming Zhang; David M Harvey; Derek R Braden

2008-01-01

261

An ultrasonic sensor for distance measurement in automotive applications  

Microsoft Academic Search

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

Alessio Carullo; Marco Parvis

2001-01-01

262

Ultrasonic Maintenance  

NASA Technical Reports Server (NTRS)

The Ultraprobe 2000, manufactured by UE Systems, Inc., Elmsford, NY, is a hand-held ultrasonic system that detects indications of bearing failure by analyzing changes in amplitude. It employs the technology of a prototype ultrasonic bearing-failure monitoring system developed by Mechanical Technology, Inc., Latham, New York and Marshall Space Flight Center (which was based on research into Skylab's gyroscope bearings). Bearings on the verge of failure send ultrasonic signals indicating their deterioration; the Ultraprobe changes these to audible signals. The operator hears the signals and gages their intensity with a meter in the unit.

1991-01-01

263

Techniques for enhancing laser ultrasonic nondestructive evaluation  

SciTech Connect

Ultrasonic nondestructive evaluation is an extremely powerful tool for characterizing materials and detecting defects. A majority of the ultrasonic nondestructive evaluation is performed with piezoelectric transducers that generate and detect high frequency acoustic energy. The liquid needed to couple the high frequency acoustic energy from the piezoelectric transducers restricts the applicability of ultrasonics. For example, traditional ultrasonics cannot evaluate parts at elevated temperatures or components that would be damaged by contact with a fluid. They are developing a technology that remotely generates and detects the ultrasonic pulses with lasers and consequently there is no requirement for liquids. Thus the research in laser-based ultrasound allows them to solve inspection problems with ultrasonics that could not be done before. This technology has wide application in many Lawrence Livermore National Laboratory programs, especially when remote and/or non-contact sensing is necessary.

Candy, J; Chinn, D; Huber, R; Spicer, J; Thomas, G

1999-02-16

264

System and technique for ultrasonic determination of degree of cooking  

DOEpatents

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.

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

265

Ultrasonic system models and measurements  

NASA Astrophysics Data System (ADS)

In this work ultrasonic models and measurements are used to characterize a number of the important elements of an ultrasonic measurement system as well as the entire system. Ultrasonic measurement models for predicting the response from reference reflectors are described, including a new ultrasonic measurement model recently developed to simulate the ultrasonic response of an infinitely long cylindrical cavity. The reference reflectors considered include spherical pores, flat-bottom holes and side-drilled holes, which are commonly used in nondestructive evaluation studies. These reflectors are employed in a series of modeling/experimental studies to assess where approximate and more exact scattering models are needed and to estimate the significance of beam variations over the reflector surface. Model-based simulated flaw responses are compared to experimentally determined flaw responses from these reference reflectors and the accuracy of the models is discussed. The role that an ultrasonic piezoelectric transducer plays in an ultrasonic measurement system can be described in terms of the transducer's input electrical impedance and its sensitivity. A new model-based method for simultaneously determining the impedance and sensitivity of commercial ultrasonic immersion transducers is developed. This method is based on a pulse-echo setup and relies only on electrical measurements. It is demonstrated that sensitivities obtained with this new method agree well with the sensitivities obtained using a more complex three-transducer method originally developed for lower-frequency acoustic transducers that has been used in many previous studies. The influence of the pulser/receiver settings on the transducer electrical impedance and sensitivity is also discussed. Cabling effects present are compensated for in the new pulse-echo method. The transducer impedance and sensitivity measurements obtained using this new pulse-echo method are combined with measurements/models for all the other electrical elements in an ultrasonic measurement system to determine a system transfer function that characterizes the effect of all the electrical and electromechanical components in the system. It is shown that by combining the system transfer function with models of the acoustic/elastic process present in a measurement system it is possible to accurately simulate the output voltage of the entire ultrasonic measurement system.

Lopez-Sanchez, Ana Lilia

266

Model representation of the transmission of high-power pulsed laser IR radiation in the fundamental absorption region in Cd x Hg1- x Te epitaxial layers  

NASA Astrophysics Data System (ADS)

A model which describes the changes in the transmission of high-power laser pulses by Cd x Hg1- x Te in view of the variations of the optical parameters of the material with temperature is presented. The thermal fields, absorptance profiles, and transmittance of the semiconductor epitaxial structure have been calculated and compared with experimental data obtained for the wavelength of a carbon dioxide laser.

Voitsekhovskii, A. V.; Shulga, S. A.; Sredin, V. G.; Talipov, N. Kh.

2011-02-01

267

Nonlinear Ultrasonic Phased Array Imaging  

NASA Astrophysics Data System (ADS)

This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging through depth.

Potter, J. N.; Croxford, A. J.; Wilcox, P. D.

2014-10-01

268

Pulse based sensor networking using mechanical waves through metal substrates  

NASA Astrophysics Data System (ADS)

This paper presents a novel wireless sensor networking technique using ultrasonic signal as the carrier wave for binary data exchange. Using the properties of lamb wave propagation through metal substrates, the proposed network structure can be used for runtime transport of structural fault information to ultrasound access points. Primary applications of the proposed sensor networking technique will include conveying fault information on an aircraft wing or on a bridge to an ultrasonic access point using ultrasonic wave through the structure itself (i.e. wing or bridge). Once a fault event has been detected, a mechanical pulse is forwarded to the access node using shortest path multi-hop ultrasonic pulse routing. The advantages of mechanical waves over traditional radio transmission using pulses are the following: First, unlike radio frequency, surface acoustic waves are not detectable outside the medium, which increases the inherent security for sensitive environments in respect to tapping. Second, event detection can be represented by the injection of a single mechanical pulse at a specific temporal position, whereas radio messages usually take several bits. The contributions of this paper are: 1) Development of a transceiver for transmitting/receiving ultrasound pulses with a pulse loss rate below 2·10-5 and false positive rate with an upper bound of 2·10-4. 2) A novel one-hop distance estimation based on the properties of lamb wave propagation with an accuracy of above 80%. 3) Implementation of a wireless sensor network using mechanical wave propagation for event detection on a 2024 aluminum alloy commonly used for aircraft skin construction.

Lorenz, S.; Dong, B.; Huo, Q.; Tomlinson, W. J.; Biswas, S.

2013-05-01

269

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

PubMed

A new adaptive beamforming algorithm for imaging via small-aperture one-dimensional 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 2.5cm 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 (ULA-OP) controlling 64 active elements on a 128-element phased array. PMID:25423646

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

2014-11-20

270

Ultrasonic imaging of textured alumina  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

271

Ultrasonic Inspection Near Small Bores  

NASA Technical Reports Server (NTRS)

Portable ultrasonic probe makes it possible to inspect for hidden cracks near insides of narrow tubes. Using pulse-echo technique, instrument detects cracks as small as 0.015-in. (0.38-mm) deep. Used for nondestructive inspection of other hard-to-reach places where conventional large transducers will not fit or where difficult to apply coupling liquid for contact ultrasonic testing. Inspects bore of tubelike fitting. Instrument makes it unnecessary to disassemble fitting to check for cracks. Precise orientation of transducer with respect to part not necessary for detecting cracks.

Parent, R. G.

1986-01-01

272

Studies on Laser Generated Ultrasonic Waves in Inconel Super Alloy  

SciTech Connect

This paper deals with the generation, characterization and analysis of ultrasonic waves generated in a thick stepped sample of inconel super alloy using Laser Based Ultrasonic Technique. Nd-YAG pulsed laser is used for ultrasonic generation while He-Ne laser is used for heterodyne detection. Ultrasonic signals are analyzed using Fourier and wavelet transforms. Here the identification and estimation of velocity of pressure waves is presented. The mechanism of pressure wave generation is discussed in brief. Laser ultrasonics studies of inconel are being reported for the first time.

Pramila, T.; Shukla, Anita [Christ Church College, Kanpur (India); Raghuram, V. [Indian Institute of Technology Kanpur, Kanpur (India)

2010-05-28

273

Out-of-plane ultrasonic velocity measurement  

DOEpatents

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.

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

1998-01-01

274

Out-of-plane ultrasonic velocity measurement  

DOEpatents

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.

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

1998-07-14

275

Ultrasonic Polishing  

NASA Technical Reports Server (NTRS)

The ultrasonic polishing process makes use of the high-frequency (ultrasonic) vibrations of an abradable tool which automatically conforms to the work piece and an abrasive slurry to finish surfaces and edges on complex, highly detailed, close tolerance cavities in materials from beryllium copper to carbide. Applications range from critical deburring of guidance system components to removing EDM recast layers from aircraft engine components to polishing molds for forming carbide cutting tool inserts or injection molding plastics. A variety of materials including tool steels, carbides, and even ceramics can be successfully processed. Since the abradable tool automatically conforms to the work piece geometry, the ultrasonic finishing method described offers a number of important benefits in finishing components with complex geometries.

Gilmore, Randy

1993-01-01

276

System of Ultrasonic Transducer Performance Detection Based on Virtual Instrument and USB 2.0 Interface Technology  

Microsoft Academic Search

Ultrasonic transducer is a key in ultrasonic equipment. The amplitude and efficiency of High-power ultrasonic transducer are two major performance indices that should be detected. Because of ultrasonic wave's high vibration frequency, high enough sampling rate and data transmission rate should be achieved to obtain the actual vibration information by which the performance of transducers can be analyzed and evaluated.

Mingwei Li; Rensheng Wang

2009-01-01

277

Inexpensive Ultrasonic Interferometer  

NASA Astrophysics Data System (ADS)

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.

Grossmann, John; Svitelskiy, Oleksiy; Suslov, Alexey

2013-03-01

278

Use of an LC transmission line to supply the discharge in a pulsed electron-beam-controlled CO laser  

Microsoft Academic Search

The first description is given of an electron-beam-controlled (EBC) CO laser with the main discharge supplied from an LC transmission line. This line significantly weakened superelastic collisions of the discharge electrons with the vibrationally excited CO molecules. The time dependences of the output radiation power of an EBC CO laser supplied from an LC transmission line were different from the

V S Kazakevich; K V Morozov; A L Petrov; G N Popkov

1994-01-01

279

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

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.

Maris, Humphrey J. (Barrington, RI)

2003-01-01

280

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

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.

Maris, Humphrey J. (Barrington, RI)

2002-01-01

281

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

NASA Astrophysics Data System (ADS)

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.

Mutlu, Ilven; Ekinci, Sinasi; Oktay, Enver

2014-06-01

282

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

NASA Astrophysics Data System (ADS)

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.

Endoh, Nobuyuki; Yamamoto, Koji

1993-05-01

283

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)

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.

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

2004-07-01

284

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

PubMed

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

Liu, Xiang; Effenberger, Frank; Chand, Naresh

2015-03-01

285

A Monte-Carlo Model for Microstructure-Induced Ultrasonic Signal Fluctuations in Titanium Alloy Inspections  

SciTech Connect

In ultrasonic inspections of some jet-engine alloys, microstructural inhomogeneities act to significantly distort the amplitude and phase profiles of the incident sonic beam, and these distortions lead in turn to ultrasonic amplitude variations. For example, in pulse/echo inspections the back-wall signal amplitude is often seen to fluctuate dramatically when scanning a transducer parallel to a flat specimen. The stochastic nature of the ultrasonic response has obvious implications for both flaw characterization and probability of detection, and tools to estimate fluctuation levels are needed. In this study, as a first step, we develop a quantitative Monte-Carlo model to predict the back-wall amplitude fluctuations seen in ultrasonic pulse/echo inspections. Inputs to the model include statistical descriptions of various beam distortion effects, namely: the lateral 'drift' of the center-of-energy about its expected position; the distortion of pressure amplitude about its expected pattern; and two types of wave-front distortion ('wrinkling' and 'tilting'). The model inputs are deduced by analyzing through-transmission measurements in which the sonic beam emerging from an immersed metal specimen is mapped using a small receiver. The mapped field is compared to the model prediction for a homogeneous metal, and statistical parameters describing the differences are deduced using the technique of 'maximum likelihood estimation' (MLE). Our modeling approach is demonstrated using rectangular coupons of jet-engine Titanium alloys, and predicted back-wall fluctuation levels are shown to be in good agreement with experiment. As a new way of modeling ultrasonic signal fluctuations, the approach outlined in this paper suggests many possibilities for future research.

Yu Linxiao; Thompson, R.B.; Margetan, F.J.; Wang Yurong [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011 (United States)

2004-02-26

286

Fabrication of acoustic superlattice LiNbO3 by pulsed current induction and its application for crossed field ultrasonic excitation  

NASA Astrophysics Data System (ADS)

An acoustic superlattice LiNbO3 crystal with periodic ferroelectric domain structure was fabricated by introducing a periodic electric current through the solid-liquid interface during the crystal growing process. The domain morphology of an as-grown crystal was observed with a scanning electron microscope, and was found to be of good periodicity. A light diffraction experiment indicated that there was a periodic fluctuation of the dielectric constant along the crystal's growing direction. Using the "crossed field" scheme, a 340 MHz ultrasonic was excited in the crystal, which means that the acoustic superlattice is suitable for constructing high-frequency bulk-wave acoustic devices.

Wan, Zhi-liang; Wang, Quan; Xi, Yuan-xin; Lu, Yan-qing; Zhu, Yong-yuan; Ming, Nai-ben

2000-09-01

287

Piezoelectric Ultrasonic Micromotors  

E-print Network

This report describes development of micro-fabricated piezoelectric ultrasonic motors and bulk-ceramic piezoelectric ultrasonic motors. Ultrasonic motors offer the advantage of low speed, high torque operation without ...

Flynn, Anita M.

1995-06-01

288

Ultrasonic inspection apparatus and method using a focused wave device  

DOEpatents

An ultrasonic pulse echo inspection apparatus and method for detecting structural failures. A focus lens is coupled to the transducer to focus the ultrasonic signal on an area to be inspected and a stop is placed in the focus lens to block selected ultrasonic waves. Other waves are not blocked and are transmitted through the structure to arrive at interfaces therein concurrently to produce an echo response with significantly less distortion.

Gieske, John H. (Albuquerque, NM); Roach, Dennis P. (Albuquerque, NM); Walkington, Phillip D. (Albuquerque, NM)

2001-01-01

289

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

290

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

SciTech Connect

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.

Cai, Hong; Liu, Sheng [Department of Physics, University of Maryland, Baltimore County (UMBC), Baltimore, Maryland 21250 (United States); Center for Advanced Studied in Photonics Research (CASPR), UMBC, Baltimore, Maryland 21250 (United States); Lalanne, Elaine [Center for Advanced Studied in Photonics Research (CASPR), UMBC, Baltimore, Maryland 21250 (United States); Guo, Dingkai; Chen, Xing; Choa, Fow-Sen [Center for Advanced Studied in Photonics Research (CASPR), UMBC, Baltimore, Maryland 21250 (United States); Department of CSEE, UMBC, Baltimore, Maryland 21250 (United States); Wang, Xiaojun [AdTech Optics, Inc., City of Industry, California 91748 (United States); Johnson, Anthony M., E-mail: amj@umbc.edu [Department of Physics, University of Maryland, Baltimore County (UMBC), Baltimore, Maryland 21250 (United States); Center for Advanced Studied in Photonics Research (CASPR), UMBC, Baltimore, Maryland 21250 (United States); Department of CSEE, UMBC, Baltimore, Maryland 21250 (United States)

2014-05-26

291

Ultrasonic transducer  

Microsoft Academic Search

An ultrasonic transducer is provided substantially at the hot spot in an engine manifold for vaporizing the fuel from the carburetor prior to entry of the fuel-air mixture into the cylinders. Transducer comprises a crystal adapted to be vibrated at a high frequency on the order of at least 1,000,000 Hz and a resonator tuned to the frequency of the

G. Csaszar; F. M. Goldman; G. Oehley; E. J. Svoboda

1983-01-01

292

Noninvasive picosecond ultrasonic detection of ultrathin interfacial layers: CFx at the AVSi interface  

E-print Network

Noninvasive picosecond ultrasonic detection of ultrathin interfacial layers: CFx at the AVSi ultrasonics technique has been used to detect interfacial fluorocarbon (CF,) layers as thin as 0.5 nm between techniqueld based on pulsed picosecond ultrasonics which is sensitive to ultrathin interfacial layers

Rubloff, Gary W.

293

DECONVOLUTION OF ULTRASONIC NONDESTRUCTIVE EVALUATION SIGNALS USING HIGHER-ORDER STATISTICS  

E-print Network

DECONVOLUTION OF ULTRASONIC NONDESTRUCTIVE EVALUATION SIGNALS USING HIGHER-ORDER STATISTICS Darmouth North Darmouth, MA 02747-2300. USA. E-mail: ghoutiBccse.kfupm.edu.sa ABSTRACT In ultrasonic of the measuring instruments, the prop- agation paths taken by the ultrasonic pulses, and are corrupted by additive

Ghouti, Lahouari

294

Including frequency-dependent attenuation for the deconvolution of ultrasonic Ewen Carcreff1,2  

E-print Network

, 72085, Le Mans, France Abstract Ultrasonic non-destructive testing (NDT) is a standard process In the context of non-destructive testing (NDT) by ultrasound, a pulse is emitted by an ultrasonic transducerIncluding frequency-dependent attenuation for the deconvolution of ultrasonic signals Ewen Carcreff

Paris-Sud XI, Université de

295

Artificial neural networks for quality control by ultrasonic testing in resistance spot welding  

Microsoft Academic Search

An artificial neural network is proposed to solve problems in the interpretation of ultrasonic oscillograms obtained by the pulse echo method. The artificial neural network classifies resistance spot welds in several quality levels through their respective ultrasonic oscillograms. The inputs of the artificial neural network are vectors obtained from each ultrasonic oscillogram with the help of a MATLAB® program. The

Óscar Martín; Manuel López; Fernando Martín

2007-01-01

296

Accurate estimation of airborne ultrasonic time-of-flight for overlapping echoes.  

PubMed

In this work, an analysis of the transmission of ultrasonic signals generated by piezoelectric sensors for air applications is presented. Based on this analysis, an ultrasonic response model is obtained for its application to the recognition of objects and structured environments for navigation by autonomous mobile robots. This model enables the analysis of the ultrasonic response that is generated using a pair of sensors in transmitter-receiver configuration using the pulse-echo technique. This is very interesting for recognizing surfaces that simultaneously generate a multiple echo response. This model takes into account the effect of the radiation pattern, the resonant frequency of the sensor, the number of cycles of the excitation pulse, the dynamics of the sensor and the attenuation with distance in the medium. This model has been developed, programmed and verified through a battery of experimental tests. Using this model a new procedure for obtaining accurate time of flight is proposed. This new method is compared with traditional ones, such as threshold or correlation, to highlight its advantages and drawbacks. Finally the advantages of this method are demonstrated for calculating multiple times of flight when the echo is formed by several overlapping echoes. PMID:24284774

Sarabia, Esther G; Llata, Jose R; Robla, Sandra; Torre-Ferrero, Carlos; Oria, Juan P

2013-01-01

297

Accurate Estimation of Airborne Ultrasonic Time-of-Flight for Overlapping Echoes  

PubMed Central

In this work, an analysis of the transmission of ultrasonic signals generated by piezoelectric sensors for air applications is presented. Based on this analysis, an ultrasonic response model is obtained for its application to the recognition of objects and structured environments for navigation by autonomous mobile robots. This model enables the analysis of the ultrasonic response that is generated using a pair of sensors in transmitter-receiver configuration using the pulse-echo technique. This is very interesting for recognizing surfaces that simultaneously generate a multiple echo response. This model takes into account the effect of the radiation pattern, the resonant frequency of the sensor, the number of cycles of the excitation pulse, the dynamics of the sensor and the attenuation with distance in the medium. This model has been developed, programmed and verified through a battery of experimental tests. Using this model a new procedure for obtaining accurate time of flight is proposed. This new method is compared with traditional ones, such as threshold or correlation, to highlight its advantages and drawbacks. Finally the advantages of this method are demonstrated for calculating multiple times of flight when the echo is formed by several overlapping echoes. PMID:24284774

Sarabia, Esther G.; Llata, Jose R.; Robla, Sandra; Torre-Ferrero, Carlos; Oria, Juan P.

2013-01-01

298

Hand-Held Ultrasonic Instrument for Reading Matrix Symbols  

NASA Technical Reports Server (NTRS)

A hand-held instrument that would include an ultrasonic camera has been proposed as an efficient means of reading matrix symbols. The proposed instrument could be operated without mechanical raster scanning. All electronic functions from excitation of ultrasonic pulses through final digital processing for decoding matrix symbols would be performed by dedicated circuitry within the single, compact instrument housing.

Schramm, Harry F.; Kula, John P.; Gurney, John W.; Lior, Ephraim D.

2008-01-01

299

Air coupled ultrasonic detection of surface defects in food cans  

Microsoft Academic Search

In this paper, we describe an ultrasonic inspection system used for detection of surface defects in food cans. The system operates in the pulse–echo mode and analyses the 220 kHz ultrasonic signal backscattered by the object. The classification of samples into valid or defective is achieved with ?2 statistics and the k nearest neighbour method, applied to features computed from

Fernando Seco; Antonio Ramón Jiménez; María Dolores del Castillo

2006-01-01

300

Ultrasonics without a Source: Thermal Fluctuation Correlations at MHz Frequencies  

Microsoft Academic Search

Noise generated in an ultrasonic receiver circuit consisting of transducer and amplifier is usually ignored, or treated as a nuisance. Here it is argued that acoustic thermal fluctuations, with displacement amplitudes of 3 fm, contain substantial ultrasonic information. It is shown that the noise autocorrelation function is the waveform that would be obtained in a direct pulse\\/echo measurement. That thesis

Richard L. Weaver; Oleg I. Lobkis

2001-01-01

301

High resolution measurements in liquid metal by focused ultrasonic wave  

Microsoft Academic Search

High spatial resolution measurements in molten zinc at temperatures more than 600 °C are performed using a focused ultrasonic pulse-echo technique with clad metallic buffer rods. The focused ultrasonic waves are generated by a spherical acoustic lens which is fabricated at the end of the buffer rod. In order to evaluate its focussing ability, several experiments are carried out in

I. Ihara; C.-K. Jen; D. Ramos França

2000-01-01

302

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

NASA Astrophysics Data System (ADS)

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.

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

2000-05-01

303

Microgravity effects on ultrasonic absorption in molten salts  

NASA Astrophysics Data System (ADS)

Measurements of ultrasonic absorption in liquids show values which exceed the classical values calculated from viscosity and heat conductions by an order of magnitude. In terrestrial experiments, the pulse-transmission and Debye-Sears methods were used to investigate the absorption in binary nitrate melts as a function of composition and frequency. The disturbances caused by convection with the optical Debye-Sears method led to experiments under microgravity conditions, in order to perform precise reference measurements. The results of the two evaluable TEXUS experiments showed, however, that the absorption was 20 and 15 percent higher, whereas lower absorption coefficients were expected. This new microgravity effect is to be confirmed in further experiments.

Merkens, W.; Richter, J.

1989-10-01

304

Ultrasonic modeling of a viscoelastic homogeneous plate A. El Mouhtadi, J. Duclos and H. Duflo  

E-print Network

Ultrasonic modeling of a viscoelastic homogeneous plate A. El Mouhtadi, J. Duclos and H. Duflo Nantes Conference 23-27 April 2012, Nantes, France 2611 #12;An ultrasonic method for determination-2 ), whereas estimated attenuation is less precise. 1 Introduction The use of ultrasonic transmission

Boyer, Edmond

305

Identification of weak ultrasonic signals in testing of metallic materials using wavelet transform  

Microsoft Academic Search

Non-destructive testing using ultrasonic signals has been widely employed to detect material damage and prevent accidents. A collected ultrasonic signal may be noisy and weak because of the grains in materials, incomplete contact between transducers and the mounting surface, and the long transmission path. Stationary wavelet transform has been applied together with kurtosis and universal de-noising to analyze ultrasonic signals

Xianfeng Fan; Ming J. Zuo; Xiaodong Wang

2006-01-01

306

Evaluation of Defects in the Seal Region of Food Packages Using the Ultrasonic Contrast  

E-print Network

, speed and safety. A US patent6 describes an ultrasonic transmission technique for testing the sealEvaluation of Defects in the Seal Region of Food Packages Using the Ultrasonic Contrast Descriptor and trays, by reducing inspection costs. To evaluate high-frequency ultrasonic imaging as a sensing method

Illinois at Urbana-Champaign, University of

307

21 CFR 1050.10 - Ultrasonic therapy products.  

Code of Federal Regulations, 2010 CFR

...amplitude exceeds the minimum pressure amplitude plus 10 percent...the maximum and minimum pressure amplitudes, and ending at the last time the pressure amplitude returns to...21) Pulse repetition rate means the repetition...Ultrasonic therapy product means: (i)...

2010-04-01

308

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

NASA Astrophysics Data System (ADS)

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.

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

309

Calcaneal ultrasonic measurements discriminate hip fracture independently of bone mass  

Microsoft Academic Search

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

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

1995-01-01

310

Transmission electron microscopy investigation of pulsed-laser deposited hydroxylapatite thin films prepared by tripod and focused ion beam techniques  

Microsoft Academic Search

Hydroxylapatite-based ceramics are largely applied as coatings and thin films on metallic components of prostheses for inducing osteoblasts apposition and subsequent bone re-growth. We report for the first time the focused ion beam technique (FIB) as a milling method to prepare specimens for transmission electron microscopy investigations of HA thin films grown on metallic substrates. New FIB technique results were

Monica Iliescu; V. Nelea; J. Werckmann; I. N. Mihailescu

2004-01-01

311

Transmission of Campylobacter spp. in a poultry slaughterhouse and genetic characterisation of the isolates by pulsed-field gel electrophoresis  

Microsoft Academic Search

1. Contamination of retail products with Campylobacter spp. during the slaughter of poultry is a well-known problem of product hygiene. Mechanical evisceration often leads to intestinal rupture and discharge of gut contents, which can contain zoonotic and human pathogens. Processes along the slaughter line cause aerosols and airborne droplets, containing bacterial loads.2. To estimate the possible transmission routes of intestinal

J. Posch; G. Feierl; G. Wuest; W. Sixl; S. Schmidt; D. U. Haas; F. F. Reinthaler; E. Marth

2006-01-01

312

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

NASA Technical Reports Server (NTRS)

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.

Hammond, P. L.

1979-01-01

313

Absolute calibration technique for broadband ultrasonic transducers  

NASA Technical Reports Server (NTRS)

Calibrating an ultrasonic transducer can be performed with a reduced number of calculations and testing. A wide-band pulser is connected to an ultrasonic transducer under test to generate ultrasonic waves in a liquid. A single frequency is transmitted to the electrostatic acoustic transducer (ESAT) and the voltage change produced is monitored. Then a broadband ultrasonic pulse is generated by the ultrasonic transducer and received by the ESAT. The output of the ESAT is amplified and input to a digitized oscilloscope for fast Fourier transform. The resulting plot is normalized with the monitored signal from the single frequency pulse. The plot is then corrected for characteristics of the membrane and diffraction effects. The transfer function of the final plot is determined. The transfer function gives the final sensitivity of the ultrasonic transducer as a function of frequency. The advantage of the system is the speed of calibrating the transducer by a reduced number of measurements and removal of the membrane and diffraction effects.

Yost, William T. (inventor); Cantrell, John H. (inventor)

1994-01-01

314

Ultrasonic pipe assessment  

DOEpatents

An ultrasonic pipe or other structure assessment system includes an ultrasonic transducer positioned proximate the pipe or other structure. A fluid connection between the ultrasonic transducer and the pipe or other structure is produced. The ultrasonic transducer is moved relative to the pipe or other structure.

Thomas, Graham H.; Morrow, Valerie L.; Levie, Harold; Kane, Ronald J.; Brown, Albert E.

2003-12-23

315

Ultrasonic Interferometers Revisited  

ERIC Educational Resources Information Center

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…

Greenslade, Thomas B., Jr.

2007-01-01

316

Ultrasonic transducer  

DOEpatents

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.

Taylor, Steven C.; Kraft, Nancy C.

2007-03-13

317

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

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

318

Flexible ultrasonic transducers.  

PubMed

Flexible ultrasonic transducers (UTs) consisting of a metal foil, a piezoelectric ceramic film, and a top electrode have been developed. The flexibility is realized owing to the porosity of piezoelectric film and the thinness of metal foil. In this paper, the stainless steel (SS), lead-zirconate-titanate (PZT)/PZT composite and silver paste were chosen as metal foil, piezoelectric film, and top electrode materials, respectively. The SS foil serves as both substrate and bottom electrode. The PZT/PZT piezoelectric composite film is made by the sol-gel spray technique. PZT/PZT films of thicknesses from 40 to 70 microm were fabricated onto SS foils. The capability of these flexible sensors operated in the pulse-echo mode for nondestructive testing on flat and curved surfaces of different materials at room temperature and 160 degrees C has been demonstrated. Numerical simulations of the effects of the metal foil thickness on the ultrasonic performance of flexible UTs also were carried out, and the results are in reasonable agreement with experimental data. In addition, a PZT/PZT flexible transducer showed a signal strength comparable with that obtained by a commercial room temperature broad bandwidth transducer. PMID:16921900

Kobayashi, Makiko; Jen, Cheng-Kuei; Lévesque, Daniel

2006-08-01

319

Calibration method for an ultrasonic gray-scale recorder  

NASA Technical Reports Server (NTRS)

Calibrated method for ultrasonic C-scanning is based on direct correlation of gray-scale response to electronic signal used. In procedure, optical density of reference recording is measured to generate curve of reflective intensity versus transmission.

Moorhead, P. E.

1978-01-01

320

Optoacoustic generation of a helicoidal ultrasonic beam  

NASA Astrophysics Data System (ADS)

The optoacoustic generation of a helicoidal ultrasonic beam is demonstrated. Such an ultrasonic ``doughnut'' beam has a pressure amplitude minimum in the center along its entire longitudinal extension, and it carries orbital angular momentum. It is produced by illuminating a specially structured absorbing surface in a water tank with pulsed laser light. The absorbing surface has a profile with a screw dislocation, similar to the transverse cross-sectional surface of a helix. Upon illumination with modulated light, a correspondingly prepared absorber generates an ultrasonic wave with the desired phase discontinuity in its wave front, which propagates through the water tank and is detected with spatial resolution using a scanning needle hydrophone. This situation can be viewed as the optoacoustic realization of a diffractive acoustical element. The method can be extended to tailor optoacoustically generated ultrasonic waves in a customized way.

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

2004-03-01

321

High resolution ultrasonic densitometer  

SciTech Connect

The velocity of torsional stress pulses in an ultrasonic waveguide of non-circular cross section is affected by the temperature and density of the surrounding medium. Measurement of the transit times of acoustic echoes from the ends of a sensor section are interpreted as level, density, and temperature of the fluid environment surrounding that section. Methods of making these measurements to obtain high resolution, temperature-corrected absolute and relative density and level determinations of the fluid are examined. Possible applications include on-line process monitoring, a hand-held density probe for battery charge state indication, and precise inventory control for such diverse fluids as uranium salt solutions in accountability storage and gasoline in service station storage tanks.

Dress, W.B.

1983-01-01

322

High resolution ultrasonic densitometer  

SciTech Connect

The velocity of torsional stress pulses in an ultrasonic waveguide of non-circular cross section is affected by the temperature and density of the surrounding medium. Measurement of the transit times of acoustic echoes from the ends of a sensor section are interpreted as level, density, and temperature of the fluid environment surrounding that section. This paper examines methods of making these measurements to obtain high resolution, temperature-corrected absolute and relative density and level determinations of the fluid. Possible applications include on-line process monitoring, a hand-held density probe for battery charge state indication, and precise inventory control for such diverse fluids as uranium salt solutions in accountability storage and gasoline in service station storage tanks.

Dress, W.B.

1983-01-01

323

A practical ultrasonic plethysmograph  

NASA Technical Reports Server (NTRS)

An ultrasonic plethysmograph, which gives improved performance over the standard Whitney Strain Gauge, is described. This instrument monitors dimension changes in human limbs by measuring the transit times of acoustic pulses across two chords of the limb. In the case of a small uniform expansion, the percentage change in limb volume is shown to be proportional to twice the percentage change in either of the measured chords. Measurement of two chords allows correction for possible non-uniform expansion. In addition, measurement of two chords allows an estimate of the absolute cross-sectional area of the limb. The developed instrument incorporates a microprocessor, which performs necessary calculation and control functions. Use of the microprocessor allows the instrument to be self-calibrating. In addition, the device can be easily reprogrammed to incorporate improvements in operating features or computational schemes.

Wu, V. C.; Nickell, W. T.; Bhagat, P. K.

1982-01-01

324

Ultrasonic hydrometer  

DOEpatents

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.degree. and 40.degree. 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.

Swoboda, Carl A. (Naperville, IL)

1984-01-01

325

Wire Crimp Termination Verification Using Ultrasonic Inspection  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

326

Numerical simulation of ultrasonic tomography inspections of highly heterogeneous materials  

NASA Astrophysics Data System (ADS)

This paper deals with the simulation of ultrasonic transmission tomography systems in water-immersed to nondestructively inspect highly heterogeneous materials with fractures. The time-domain Elastodynamic Finite Integration Technique (EFIT) was employed for all numerical simulations because is able to reliably simulate this type of ultrasonic problems. The EFIT code was implemented using OpenCL and PyOpenCL. Several ultrasonic tomography inspection setups were numerically simulated under different conditions varying the number of ultrasonic sources and their size and number and different operation schemes. Sinograms of concrete scenarios were computed and compared for each configuration, using homogeneous materials with similar fracture types and experimentally validated.

Molero, M.; Medina, L.; Lluveras, D.; Izquierdo, M. A. G.; Anaya, J. J.

2012-12-01

327

Gold-aluminum wirebond interface testing using laser-induced ultrasonic energy  

Microsoft Academic Search

A new, non-destructive method of testing wirebonded interfaces is under development. The method uses thermoelastically-generated pulse of ultrasonic waves as a probe. This ultrasonic wave is generated in a gold ball's surface by rapid heating with a laser pulse; it then travels through the bonded interface, and is detected on the surface of the die by an interferometer. Numerical reduction

B. M. Romenesko; J. A. Cristion; B. K. Siu

2000-01-01

328

Self-phase-modulation-based 2R regenerator including pulse compression and offset filtering for 42.6 Gbit/s RZ-33% transmission systems.  

PubMed

We report on the experimental and theoretical study of a self-phase-modulation-based regenerator at 42.6 Gbit/s with a return-to-zero 33% format. We point out some detrimental effects such as intrachannel interactions and Brillouin scattering. An efficient solution, relying on a self-phase-modulation-based pulse compressor in combination with the regenerator, is proposed to overcome these detrimental phenomena. The experimental demonstration shows the effectiveness of a wavelength-transparent regenerator at 42.6 Gbit/s with a sensitivity-improvement of more than 5 dB and an eye-opening improvement of 2.3 dB in a back-to-back configuration, as well as a 10 times maximum transmission distance improvement for a BER of 10(-4). PMID:19907561

Nguyen, Thanh Nam; Chartier, Thierry; Bramerie, Laurent; Gay, Mathilde; Le, Quang Trung; Lobo, Sebastien; Joindot, Michel; Simon, Jean-Claude; Fatome, Julien; Finot, Christophe

2009-09-28

329

Federal technology alert: Ultrasonic humidifiers  

SciTech Connect

Humidifiers are used in buildings to maintain humidity levels to ensure quality and handling capabilities in manufacturing processes, to lower the transmission rate of disease-causing bacteria in hospitals, to reduce static electricity in manufacturing clean rooms and in computer rooms, and to provide higher levels of employee comfort in offices. Ultrasonic humidifiers generate a water mist without raising its temperature. An electronic oscillation is converted to a mechanical oscillation using a piezo disk immersed in a reservoir of mineral-free water. The mechanical oscillation is directed at the surface of the water, where at very high frequencies it creates a very fine mist of water droplets. This adiabatic process, which does not heat the supply water, reduces humidifier energy use by 90 to 93% compared with systems that do boil the water. Ultrasonic humidifiers have been demonstrated to be more efficient and to require less maintenance than competing humidifier technologies such as electrode canisters, quartz lamps, and indirect steam-to-steam. They do not require anticorrosive additives that affect the indoor air quality of buildings using direct steam humidifiers. There are two potential disadvantages of ultrasonic humidifiers. They must use mineral-free, deionized water or water treated with reverse osmosis. Treated water reduces maintenance costs because it eliminates calcium deposits, but increases other operating costs. Also, the cool mist from ultrasonic humidifiers absorbs energy from the supply air as it evaporates and provides a secondary cooling effect.

NONE

1998-11-01

330

Computer simulation of ultrasonic testing for aerospace vehicle  

NASA Astrophysics Data System (ADS)

Non-destructive testing techniques are developed to secure reliability of aerospace vehicles used repetitively. In the case of cracks caused by thermal stress on walls in combustion chambers of liquid-fuel rockets, it is examined by ultrasonic waves visualization technique developed in AIST. The technique is composed with non-contact ultrasonic generation by pulsed-laser scanning, piezoelectric transducer for the ultrasonic detection, and image reconstruction processing. It enables detection of defects by visualization of ultrasonic waves scattered by the defects. In NIMS, the condition of the detection by the visualization is investigated using computer simulation for ultrasonic propagation that has capability of fast 3-D calculation. The simulation technique is based on finite-difference method and two-step elastic wave equations. It is reported about the investigation by the calculation, and shows availability of the simulation for the ultrasonic testing technique of the wall cracks.

Yamawaki, H.; Moriya, S.; Masuoka, T.; Takatsubo

2011-01-01

331

Prototype ultrasonic instrument for quantitative testing  

NASA Technical Reports Server (NTRS)

Ultrasonic instrument has been developed for use in quantitative nondestructive evaluation of material defects such as cracks, voids, inclusions, and unbonds. Instrument is provided with standard pulse source and transducer for each frequency range selected and includes integral aids that allow calibration to prescribed standards.

Lynworth, L. C.; Dubois, J. L.; Kranz, P. R.

1973-01-01

332

Production of aqueous spherical gold nanoparticles using conventional ultrasonic bath  

PubMed Central

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

2012-01-01

333

An adaptive neuro fuzzy inference system controlled space cector pulse width modulation based HVDC light transmission system under AC fault conditions  

NASA Astrophysics Data System (ADS)

In HVDC Light transmission systems, converter control is one of the major fields of present day research works. In this paper, fuzzy logic controller is utilized for controlling both the converters of the space vector pulse width modulation (SVPWM) based HVDC Light transmission systems. Due to its complexity in the rule base formation, an intelligent controller known as adaptive neuro fuzzy inference system (ANFIS) controller is also introduced in this paper. The proposed ANFIS controller changes the PI gains automatically for different operating conditions. A hybrid learning method which combines and exploits the best features of both the back propagation algorithm and least square estimation method is used to train the 5-layer ANFIS controller. The performance of the proposed ANFIS controller is compared and validated with the fuzzy logic controller and also with the fixed gain conventional PI controller. The simulations are carried out in the MATLAB/SIMULINK environment. The results reveal that the proposed ANFIS controller is reducing power fluctuations at both the converters. It also improves the dynamic performance of the test power system effectively when tested for various ac fault conditions.

Ajay Kumar, M.; Srikanth, N.

2014-03-01

334

Ultrasonic P-wave and S-wave attenuation in partially frozen porous material saturated with brine  

NASA Astrophysics Data System (ADS)

Ultrasonic wave transmission measurements were conducted in order to examine the influence of ice-brine coexisting system grown in porous material on ultrasonic P- and S-waves. We observed the variations of a transmitted wave with a frequency content of 150-1000 kHz through a liquid system to a solid-liquid coexistence system, changing its temperature from 20°C to -15°C. We quantitatively estimated attenuation for porous materials with two different porosities (37.3 and 48.2 %) during the freezing of salty water in porous material by considering different distances between the source and receiver transducers. This paper is concerned with attenuation at ultrasonic frequencies of 500-1000 kHz for P-waves and 100-400 kHz for S-waves. The waveform analyses indicate that the attenuation curves reach their peak at a temperature of -3°C and gradually decrease with decreasing temperature. We found a positive correlation between the attenuation of ultrasonic waves and the existence of unfrozen brine estimated by the pulsed nuclear magnetic resonance (NMR) technique. Thus, the laboratory experiments of the present study demonstrated that ultrasonic waves with such a frequency range are significantly affected by the existence of a solid-liquid coexistence system in the porous material. In terms of a plausible mechanism for attenuation, we must consider the physical interactions between pore fluid and ice, that is, the pore microstructure and permeability in such system is important. Furthermore, We demonstrate a method that derives a more accurate measurement of ultrasonic attenuation by using sweep-type signals than by using impulse-type signals. We obtained spectral amplitude of the sweep signal in frequency-time domain using the continuous wavelet transform (CWT) and estimated attenuation in the time-frequency domain using the spectral-ratio method. The advantage of this method is independent on the effect of windowing. Finally we demonstrated the possibility of sweep signal to estimate attenuation.

Matsushima, J.; Suzuki, M.; Kato, Y.; Rokugawa, S.

2010-12-01

335

Ultrasonic analysis of bolt preloads  

NASA Technical Reports Server (NTRS)

This paper covers an investigation into the feasibility of analyzing bolt preloads by ultrasonic techniques. Various techniques were evaluated and a pulse echo inteferometric method was selected for experimental testing. In agreement with theoretical predictions, the interferometer response was found to be linearly related to tensile stresses oriented parallel to the bolt axis. Under rather idealized conditions, bolt loads can be determined with errors of less than 1%. The ultimate operational accuracy depends on a number of variables, such as bolt dimensions and geometry, bolt temperature, uniformity of stresses, and bolt materials, but load analyses to within + or - 3% are readily achievable. Best results are obtained with the ultrasonic transducer contact coupled to a small flat area near the center of the bolt head. The transducer can be applied and measurements made without interfering with normal wrenching operations. Prototype instrumentation is described and calibration results are tabulated for numerous bolt sizes and materials.

Rollins, F. R., Jr.

1977-01-01

336

Fundamentals of picosecond laser ultrasonics.  

PubMed

The aim of this article is to provide an introduction to picosecond laser ultrasonics, a means by which gigahertz-terahertz ultrasonic waves can be generated and detected by ultrashort light pulses. This method can be used to characterize materials with nanometer spatial resolution. With reference to key experiments, we first review the theoretical background for normal-incidence optical detection of longitudinal acoustic waves in opaque single-layer isotropic thin films. The theory is extended to handle isotropic multilayer samples, and is again compared to experiment. We then review applications to anisotropic samples, including oblique-incidence optical probing, and treat the generation and detection of shear waves. Solids including metals and semiconductors are mainly discussed, although liquids are briefly mentioned. PMID:24998119

Matsuda, Osamu; Larciprete, Maria Cristina; Li Voti, Roberto; Wright, Oliver B

2015-02-01

337

Autonomous data transmission apparatus  

DOEpatents

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.

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

1997-01-01

338

Autonomous data transmission apparatus  

DOEpatents

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.

Kotlyar, O.M.

1997-03-25

339

System and method for ultrasonic tomography  

DOEpatents

A system and method for doing both transmission mode and reflection mode three-dimensional ultrasonic imagining. The multimode imaging capability may be used to provide enhanced detectability of cancer tumors within human breast, however, similar imaging systems are applicable to a number of other medical problems as well as a variety of non-medical problems in non-destructive evaluation (NDE).

Haddad, Waleed Sami (Dublin, CA)

2002-01-01

340

The quasi-harmonic ultrasonic polar scan for material characterization: Experiment and numerical modeling.  

PubMed

Conventionally, the ultrasonic polar scan (UPS) records the amplitude or time-of-flight in transmission using short ultrasonic pulses for a wide range of incidence angles, resulting in a fingerprint of the critical bulk wave angles of the material at the insonified spot. Here, we investigate the use of quasi-harmonic ultrasound (bursts) in a polar scan experiment, both experimentally and numerically. It is shown that the nature of the fingerprint drastically changes, and reveals the positions of the leaky Lamb angles. To compare with experiments, both plane wave and bounded beam simulations have been performed based on the recursive stiffness matrix method. Whereas the plane wave computations yield a pure Lamb wave angle fingerprint, this is no longer valid for the more realistic case of a bounded beam. The experimental recordings are fully supported by the bounded beam simulations. To complement the traditional amplitude measurement, experimental and numerical investigations have been performed to record, predict and analyze the phase of the transmitted ultrasonic beam. This results in the conceptual introduction of the 'phase polar scan', exposing even more intriguing and detailed patterns. In fact, the combination of the amplitude and the phase polar scan provides the complete knowledge about the complex transmission coefficient for every possible angle of incidence. This comprehensive information will be very valuable for inverse modeling of the local elasticity tensor based on a single UPS experiment. Finally, the UPS method has been applied for the detection of an artificial delamination. Compared to the pulsed UPS, the quasi-harmonic UPS (both the amplitude and phase recording) shows a superior sensitivity to the presence of a delamination. PMID:25620710

Kersemans, Mathias; Martens, Arvid; Van Den Abeele, Koen; Degrieck, Joris; Pyl, Lincy; Zastavnik, Filip; Sol, Hugo; Van Paepegem, Wim

2015-04-01

341

Modeling of ultrasonic processing  

E-print Network

This paper presents a finite element analysis (FEA) of ultrasonic processing of an aerospace-grade carbon-epoxy composite laminate. An ultrasonic (approximately 30 kHz) loading horn is applied to a small region at the ...

Zhao, Wenguang, S.M. Massachusetts Institute of Technology

2005-01-01

342

A unique method to study acoustic transmission through ducts using signal synthesis and averaging of acoustic pulses  

NASA Technical Reports Server (NTRS)

An acoustic impulse technique using a loudspeaker driver is developed to measure the acoustic properties of a duct/nozzle system. A signal synthesis method is used to generate a desired single pulse with a flat spectrum. The convolution of the desired signal and the inverse Fourier transform of the reciprocal of the driver's response are then fed to the driver. A signal averaging process eliminates the jet mixing noise from the mixture of jet noise and the internal noise, thereby allowing very low intensity signals to be measured accurately, even for high velocity jets. A theoretical analysis is carried out to predict the incident sound field; this is used to help determine the number and locations of the induct measurement points to account for the contributions due to higher order modes present in the incident tube method. The impulse technique is validated by comparing experimentally determined acoustic characteristics of a duct-nozzle system with similar results obtained by the impedance tube method. Absolute agreement in the comparisons was poor, but the overall shapes of the time histories and spectral distributions were much alike.

Salikuddin, M.; Ramakrishnan, R.; Ahuja, K. K.; Brown, W. H.

1981-01-01

343

Non-contact weight measurement of flat-faced pharmaceutical tablets using terahertz transmission pulse delay measurements.  

PubMed

By measuring the time delay of a terahertz pulse traversing a tablet, and hence its effective refractive index, it is possible to non-invasively and non-destructively detect the weight of tablets made of microcrystalline cellulose (MCC). Two sets of MCC tablets were used in the study: Set A (training set) consisted of 13 tablets with nominally constant height but varying porosities, whereas Set B (test set) comprised of 21 tablets with nominally constant porosity but different heights. A linear correlation between the estimated absolute weight based on the terahertz measurement and the measured weight of both sets of MCC tablets was found. In addition, it was possible to estimate the height of the tablets by utilizing the estimated absolute weight and calculating the relative change of height of each tablet with respect to an ideal tablet. A good agreement between the experimental and the calculated results was found highlighting the potential of this technique for in-line sensing of the weight, porosity and the relative change in height of the tablets compared to a reference/ideal tablet. In this context, we propose a quantitative quality control method to assess the deviations in porosity of tablets immediately after compaction. PMID:25245546

Bawuah, Prince; Silfsten, Pertti; Ervasti, Tuomas; Ketolainen, Jarkko; Zeitler, J Axel; Peiponen, Kai-Erik

2014-12-10

344

Analysis of microcracks in dry polycrystalline NaCl by ultrasonic signal processing  

SciTech Connect

The attenuation of energy and the change in shape of transient waveforms is a basic feature associated with the propagation of waves in crustal rocks. The dimensionless quality factor Q is observed as a useful quantity to characterize the attenuation of energy. Existing an elastic (attenuation) theories on the Q-determination problem are compared with experimental measurements to better understand rock properties. Experimental attenuation measurements were made on Avery Island (Louisiana) rock salt, Westerly (Rhode Island) granite, and Creighton (Ontario) quartz biotite gabbro. The attenuation mechanisms and how they affect the agreement between the an elastic theories were examined. Ultrasonic pulse methods were utilized of examine crack geometries as a function of frequency and thermal cycling temperature in dry polycrystalline rock salt. The attenuation of compressional (P) and shear (S) waves was studied in a thermally-induced, isotropic distribution of microcracks using ultrasonic-transmission techniques. These attenuation measurements led to the following series of generalities: ultrasonic or seismic attenuation depends on frequency in the rocks tested; thermal cycling of rock salt increases the porosity and attenuation; grain scattering seems to be the dominant loss mechanism at the higher frequencies in rocks; friction explains why the introduction of cracks into rock salt increases the attenuation; and attenuation appears to be independent of strain amplitude for low strains (10/sup -6/) such as those associated with these measurements. Much work remains to be done to adequately describe the attenuation loss mechanisms and the an elasticity of rocks both experimentally and theoretically.

Sears, F.M.

1980-07-01

345

Ultrasonic and mechanical characterizations of fatigue states of graphite epoxy composite laminates  

NASA Technical Reports Server (NTRS)

Results of an exploration of the relationship between ultrasonic attenuation and fatigue survivability of graphite fiber epoxy composites fabricated under different cure conditions are reported. A total of 9 27 x 40 cm eight-ply graphite epoxy laminated specimens were formed, and fatigue tests were run on five partial samples at 73.5 N varying at 30 Hz, with tests ending at a 1.27 cm deflection. A pulsed oscillator generated sinusoidal waves and transducers recorded the passage of the ultrasonic waves for display on oscilloscopes. Cure pressures ranged from 0.52-0.85 MPa and cure temperatures were in the 150-200 C interval. Ultrasonic through-transmission at 4 MHz was performed prior to and during fatigue testing. The minimum void volume fraction occurred at 175 C and 0.86 MPa. The flexural stiffness decreased with the number of fatigue cycles past 10,000, when the attenuation also increased. Correlations were found between the 4.0 MHz signal attenuation and the void volume fraction, and between the number of fatigue cycles to failure and the 4.0 MHz signal attenuation.

Williams, J. H., Jr.; Lee, S. S.; Yuce, H.

1982-01-01

346

PHASEBASED ULTRASONIC DEFORMATION ESTIMATION  

E-print Network

PHASE­BASED ULTRASONIC DEFORMATION ESTIMATION J. E. Lindop, G. M. Treece, A. H. Gee and R. W Cambridge CB2 1PZ United Kingdom Email: jel35/gmt11/ahg/rwp @eng.cam.ac.uk #12; PHASE­BASED ULTRASONIC theoretical analysis and experimental results for an inves­ tigation of phase­based ultrasonic deformation

Drummond, Tom

347

Piezoelectric ultrasonic motors: overview  

Microsoft Academic Search

This paper reviews recent developments of ultrasonic motors using piezoelectric resonant vibrations. Following the historical background, ultrasonic motors using standing and traveling waves are introduced. Driving principles and motor characteristics are explained in comparison with conventional electromagnetic motors. After a brief discussion on speed and thrust calculation, finally, reliability issues of ultrasonic motors are described.

Kenji Uchino

1998-01-01

348

A novel ultrasonic method for characterizing suspensions of nanoparticles  

Microsoft Academic Search

The Ultrasonic Pulsed Doppler (USPD) technique for characterization of nanoparticle suspensions is described. This method uses a single transducer as both source and receiver of pulsed ultrasound to measure backscattered energy from suspended and moving particles. Particle motion can be provided mechanically (e.g., by stirring or unidirectional flow) or by acoustic streaming generated by the interrogating acoustic field itself. The

Steven Africk

2005-01-01

349

Torsional ultrasonic technique for LWR liquid-level measurement  

SciTech Connect

Since 1980, the Instrumentation and Controls Division of ORNL has been involved in the evaluation of sensors using torsional ultrasonic pulses to make level and density measurements, and extensional ultrasonic pulses for temperature measurements and correction of the torsional measurements. Work at ORNL through 1981 demonstrated the feasibility of transmitting torsional pulses in a ribbon of stainless steel and the sensor was used to measure the level of a steam/water interface at 290/sup 0/C and 10 MPa. Subsequent work under the Advanced Two-Phase Instrumentation Program has been directed towards an operational prototype instrument that can be installed in functional power reactor.

Dress, W.B.

1983-01-01

350

M-ary pulse-position modulation and frequency-shift keying with additional polarization/phase modulation for high-sensitivity optical transmission.  

PubMed

We present a new class of optical modulation formats based on the combination of m-ary pulse-position modulation (m-PPM) or m-ary frequency-shift keying (FSK) with additional polarization and/or phase modulation, which is applied on the information carrying pulses in the case of m-PPM or on the information carrying frequency carriers in the case of m-FSK. We describe the principle and implementation of this class of optical modulation formats, and formulate their theoretical receiver sensitivities in optically pre-amplified receivers. Pilot-assisted frequency-domain equalization, similar to that used in coherent optical orthogonal frequency-division multiplexing (CO-OFDM), is used for reliable channel estimation and compensation. CO-OFDM also allows m-FSK to be implemented with high spectral efficiency. As a particular format in this class, m-PPM in combination with polarization-division-multiplexed quadrature phase-shift keying (PDM-QPSK), termed as PQ-mPPM, offers superior receiver sensitivity in optically pre-amplified receivers at bit error ratios (BERs) around the thresholds of common forward-error correction codes. Record receiver sensitivities of 3.5 photons per bit (ppb) at BER = 10(-3) and 2.7 ppb at BER = 1.5 × 10(-2) are experimentally demonstrated at 2.5 Gb/s and 6.23 Gb/s using PQ-16PPM and PQ-4PPM, respectively. We further demonstrate the transmission of a 6.23-Gb/s PQ-4PPM signal over a 370-km unrepeatered ultra-large-area-fiber span with 71.7-dB total loss budget. PMID:22274115

Liu, Xiang; Chandrasekhar, S; Wood, T H; Tkach, R W; Winzer, P J; Burrows, E C; Chraplyvy, A R

2011-12-12

351

Design of embedded endoscopic ultrasonic imaging system  

NASA Astrophysics Data System (ADS)

Endoscopic ultrasonic imaging system is an important component in the endoscopic ultrasonography system (EUS). Through the ultrasonic probe, the characteristics of the fault histology features of digestive organs is detected by EUS, and then received by the reception circuit which making up of amplifying, gain compensation, filtering and A/D converter circuit, in the form of ultrasonic echo. Endoscopic ultrasonic imaging system is the back-end processing system of the EUS, with the function of receiving digital ultrasonic echo modulated by the digestive tract wall from the reception circuit, acquiring and showing the fault histology features in the form of image and characteristic data after digital signal processing, such as demodulation, etc. Traditional endoscopic ultrasonic imaging systems are mainly based on image acquisition and processing chips, which connecting to personal computer with USB2.0 circuit, with the faults of expensive, complicated structure, poor portability, and difficult to popularize. To against the shortcomings above, this paper presents the methods of digital signal acquisition and processing specially based on embedded technology with the core hardware structure of ARM and FPGA for substituting the traditional design with USB2.0 and personal computer. With built-in FIFO and dual-buffer, FPGA implement the ping-pong operation of data storage, simultaneously transferring the image data into ARM through the EBI bus by DMA function, which is controlled by ARM to carry out the purpose of high-speed transmission. The ARM system is being chosen to implement the responsibility of image display every time DMA transmission over and actualizing system control with the drivers and applications running on the embedded operating system Windows CE, which could provide a stable, safe and reliable running platform for the embedded device software. Profiting from the excellent graphical user interface (GUI) and good performance of Windows CE, we can not only clearly show 511×511 pixels ultrasonic echo images through application program, but also provide a simple and friendly operating interface with mouse and touch screen which is more convenient than the traditional endoscopic ultrasonic imaging system. Including core and peripheral circuits of FPGA and ARM, power network circuit and LCD display circuit, we designed the whole embedded system, achieving the desired purpose by implementing ultrasonic image display properly after the experimental verification, solving the problem of hugeness and complexity of the traditional endoscopic ultrasonic imaging system.

Li, Ming; Zhou, Hao; Wen, Shijie; Chen, Xiodong; Yu, Daoyin

2008-12-01

352

A self-calibrating technique for the ultrasonic discrimination of solid-state welds  

Microsoft Academic Search

This paper presents the description and application of a self-calibrating technique for ultrasonic weld discrimination. A broad-band ultrasonic transducer is bonded to one side of the component containing the weld. The transducer transmits and receives short pulses in the pulse-echo mode. The received short pulses are processed to provide data on weld quality. The technique is self-calibrating in the sense

B. R. Tittmann; B. H. Hosten

1988-01-01

353

Passive wireless ultrasonic transducer systems  

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

354

P1H-6 Picosecond Ultrasonics as a Helpful Technique for Introducing a New Electrode Material in BAW Technology: The Iridium Case  

Microsoft Academic Search

We present picosecond ultrasonic characterizations on e-beam evaporated Ir thin films and on AlN films deposited by pulsed DC reactive sputtering on Ir. Picosecond ultrasonics is an optical technique which uses ultrashort laser pulses to generate and detect very short acoustic pulses. We first investigate the properties of the Ir films by measuring samples of various thicknesses and deposition parameters.

A. Devos; J. Olivares; M. Clement; E. Iborra; S. Gonzalez-Castilla; N. Rimmer; A. Rastogi

2007-01-01

355

Ultrasonic angle beam standard reflector. [ultrasonic nondestructive inspection  

NASA Technical Reports Server (NTRS)

A method that provides an impression profile in a reference standard material utilized in inspecting critically stressed components with pulsed ultrasound is described. A die stamp having an I letter is used to impress the surface of a reference material. The die stamp is placed against the surface and struck with an inertia imparting member to impress the I in the reference standard material. Upset may appear on the surface as a result of the impression and is removed to form a smooth surface. The stamping and upset removal is repeated until the entire surface area of a depth control platform on the die stamp uniformly contacts the material surface. The I impression profile in the reference standard material is utilized for reflecting pulsed ultrasonic beams for inspection purposes.

Berry, R. F., Jr. (inventor)

1985-01-01

356

Ultrasonic Method for Measuring Internal Temperature Profile in Heated Materials  

NASA Astrophysics Data System (ADS)

A new ultrasonic method for internal temperature measurement is presented. The principle of the method is based on temperature dependence of the velocity of the ultrasonic wave propagating through the material. An inverse analysis to determine the temperature profile in a heated material is developed and an experiment is carried out to verify the validity of the developed method. A single side of a silicone rubber plate of 30 mm thickness is heated and ultrasonic pulse-echo measurements are then performed during heating. A change in transit time of ultrasonic wave in the heated rubber plate is monitored and used to determine the transient variation in internal temperature distribution of the rubber. The internal temperature distribution determined ultrasonically agrees well with both obtained using commercial thermocouples installed in the rubber and estimated theoretically.

Ihara, I.; Takahashi, M.

2008-02-01

357

Ultrasonic Monitoring of Internal Temperature Distribution in a Heated Material  

NASA Astrophysics Data System (ADS)

An ultrasonic method for internal temperature monitoring is presented. The principle of the method is based on the temperature dependence of ultrasonic velocity in materials. An inverse analysis to determine the one-dimensional temperature gradient in a heated plate is developed and an experiment is carried out to verify the validity of the developed method. A single side of a silicone rubber plate of 30 mm thickness is heated and ultrasonic pulse-echo measurements are then performed during heating. A change in the transit time of ultrasonic waves in the heated rubber is monitored and used to determine the transient variation in the internal temperature gradient of the rubber. The internal temperature gradient determined ultrasonically agrees well with both results obtained using commercial thermocouples installed in the rubber and estimated theoretically.

Takahashi, Manabu; Ihara, Ikuo

2008-05-01

358

Acousto-ultrasonic characterization of fiber reinforced composites  

NASA Technical Reports Server (NTRS)

The acousto-ultrasonic technique combines advantageous aspects of acoustic emission and ultrasonic methodologies. Acousto-ultrasonics operates by introducing a repeating series of ultrasonic pulses into a material. The waves introduced simulate the spontaneous stress waves that would arise if the material were put under stress as in the case of acoustic emission measurements. These benign stress waves are detected by an acoustic emission sensor. The physical arrangement of the ultrasonic (input) transducer and acoustic emission (output) sensor is such that the resultant waveform carries an imprint of morphological factors that govern or contribute to material performance. The output waveform is complex, but it can be quantitized in terms of a 'stress wave factor.' The stress wave factor, which can be defined in a number of ways, is a relative measure of the efficiency of energy dissipation in a material. If flaws or other material anomalies exist in the volume being examined, their combined effect appears in the stress wave factor.

Vary, A.

1981-01-01

359

ULTRASONIC EXAMINATION OF TYPE IV CRACKING IN HIGH ENERGY STEAM PIPING USING TOFD AND PHASE ARRAY TECHNIQUES  

Microsoft Academic Search

Type IV creep damage in welded high energy piping has been an industry problem over the years. Ultrasonic examination is one technique that helps detect creep damage at early stages. Current ultrasonic methods range from traditional pulse echo techniques, that requires a traditional raster scan, to the time of flight Diffraction (TOFD) technique, that requires a traditional pulse echo technique

H. Fukutomi; S. Lin; A. Nitta

360

High voltage pulse conditioning  

DOEpatents

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.

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

1990-01-01

361

Air coupled ultrasonic detection of surface defects in food cans  

Microsoft Academic Search

In this paper, we describe an ultrasonic inspection system used for detection of surface defects in food cans. The system operates in the pulse-echo mode and analyses the 220 kHz ultrasonic signal backscattered by the object. The classification of samples into valid or defective is achieved with chi2 statistics and the k nearest neighbour method, applied to features computed from

Fernando Seco; Antonio Ramón Jiménez; María Dolores del Castillo

2006-01-01

362

The characterization of capacitive micromachined ultrasonic transducers in air  

Microsoft Academic Search

Surface micromachined, capacitive ultrasonic transducers have been fabricated using a low thermal budget, CMOS-compatible process. They exhibit interesting properties for transduction in air at frequencies in excess of 1 MHz, when driven from a standard ultrasonic voltage source. Experiments are described using 1 mm square devices in air, operating in both pitch-catch and pulse-echo modes. The dependence on d.c. bias

J. S. McIntosh; D. A. Hutchins; D. R. Billson; T. J. Robertson; R. A. Noble; A. D. R. Jones

2002-01-01

363

Controlled-Shape, Ultrasonic-Angle-Beam Standard Reflector  

NASA Technical Reports Server (NTRS)

New ultrasonic angle-beam standard reflector uses impression of letter "l" steel-die stamp. NDE techniques and standard reflector apply to use of pulse-echo-type ultrasonic equipment for inspection of wrought metals including forgings and forging stock; rolled billet, bar or plate; and extruded bar, tube, and shapes. "l" reference standard reflector affords advantages of easy insertion in inspected item using common hand-tools and greatly reduced implementation time through elimination of machining operations.

Berry, J., Robertf.

1986-01-01

364

Real-time ultrasonic sensing of arc welding processes  

Microsoft Academic Search

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

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

1983-01-01

365

Measurement of intergranular attack in stainless steel using ultrasonic energy  

DOEpatents

Ultrasonic test methods are used to measure the depth of intergranular attack (IGA) in a stainless steel specimen. The ultrasonic test methods include a pitch-catch surface wave technique and a through-wall pulse-echo technique. When used in combination, these techniques can establish the extent of IGA on both the front and back surfaces of a stainless steel specimen from measurements made on only one surface.

Mott, Gerry (Pittsburgh, PA); Attaar, Mustan (Monroeville, PA); Rishel, Rick D. (Monroeville, PA)

1989-08-08

366

Generation of extreme ultrasonics in rainforest katydids.  

PubMed

The calling song of an undescribed Meconematinae katydid (Tettigoniidae) from South America consists of trains of short, separated pure-tone sound pulses at 129 kHz (the highest calling note produced by an Arthropod). Paradoxically, these extremely high-frequency sound waves are produced by a low-velocity movement of the stridulatory forewings. Sound production during a wing stroke is pulsed, but the wings do not pause in their closing, requiring that the scraper, in its travel along the file, must do so to create the pulses. We hypothesize that during scraper pauses, the cuticle behind the scraper is bent by the ongoing relative displacement of the wings, storing deformation energy. When the scraper slips free it unbends while being carried along the file and its deformation energy contributes to a more powerful, higher-rate, one-tooth one-wave sound pulse, lasting no more than a few waves at 129 000 Hz. Some other katydid species make pure-tone ultrasonic pulses. Wing velocities and carriers among these pure-tone species fall into two groups: (1) species with ultrasonic carriers below 40 kHz that have higher calling frequencies correlated with higher wing-closing velocities and higher tooth densities: for these katydids the relationship between average tooth strike rate and song frequency approaches 1:1, as in cricket escapement mechanisms; (2) a group of species with ultrasonic carriers above 40 kHz (that includes the Meconematinae): for these katydids closing wing velocities are dramatically lower and they make short trains of pulses, with intervening periods of silence greater than the duration of the pulses they separate. This signal form may be the signature of scraper-stored elastic energy. PMID:17142681

Montealegre-Z, Fernando; Morris, Glenn K; Mason, Andrew C

2006-12-01

367

Coherent ultrasonic Doppler tomography.  

PubMed

Ultrasonic imaging based on the pulse-echo principle is widely used throughout the world, particularly in medical applications. However, its spatial resolution is poor (around 2 times the wavelength, or 200 ?m at 15 MHz), limiting its ability to detect small but clinically important lesions (such as microcalcifications in breast cancer). The work presented here is different from the traditional approach. Continuous-wave ultrasound is transmitted to insonate a rotating object, then the amplitude and phase of the returned signals are coherently processed to reconstruct a Doppler tomographic image of the object's backscatter field. It is demonstrated numerically that the spatial resolution is up to 0.19 wavelengths and the sampling requirement and image formation method are given. To show the performance of the method, we present the results obtained by applying the new technique in simulation and experiment. A string phantom consisting of very thin copper wires and two cylindrical phantoms constructed by tissue-mimicking-material were scanned. It is demonstrated that the copper wires were located very accurately with very high spatial resolution, and good shape approximation for the cylindrical phantoms was achieved. PMID:21376452

Tsui, Chun Sing Louis; Liang, Hai-Dong; Halliwell, Michael; Shere, Mike; Braybrooke, Jeremy P; Whipp, Elisabeth; Wells, Peter N T

2011-04-01

368

Ultrasensitive ultrasonic transducer studies  

SciTech Connect

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project sought to continue development of the ultrasensitive ultrasonic transducers that won a 1994 R&D 100 Award. These transducers have a very smooth response across a broad frequency range and thus are extremely well- suited for resonant ultrasound spectroscopy as well as pulsed-echo and acoustic-emission applications. Current work on these transducers has indicated that bonding the piezoelectric and wear surface to a metal foil and attaching the foil to a body is less expensive and produces a transducer that is as good or better than commercially produced transducers. We have diffusion- bonded piezoelectric crystals and backings to stainless-steel-foil and wear surfaces. These are then attached onto stainless-steel tubes with electrical connectors to form the transducers. The transducers have been characterized using a reciprocity technique, electrical response, and optical interferometry. After characterization, the transducers have been compared to existing transducers by measuring and testing identical properties.

Dixon, R.; Darling, T.; Migliori, A.

1996-09-01

369

Continuous Ultrasonic Inspection of Extruded Wood-Plastic Composites  

SciTech Connect

Nondestructive evaluation (NDE) techniques are needed for in-line monitoring of wood-plastic composite (WPC) quality during manufacturing for process control. Through-transmission ultrasonic inspection is useful in characterizing stiffness and detecting cracks and voids in a range of materials; however, little is documented about ultrasound propagation in WPC materials. The objectives of this research were to determine applicable ultrasonic transducer frequencies, coupling methods, configurations and placements for wave speed monitoring and web defect detection within an extrusion process; to quantify the effects of temperature on ultrasonic parameters; and to develop a prototype ultrasonic inspection system for a full-size extrusion line. An angled beam, water-coupled ultrasonic inspection system using a pair of 50-kHz narrowband transducers was adequate for monitoring wave speed parallel to the extrusion direction. For locating internal web defects, water-coupled, 500-kHz broadband ultrasonic transducers were used in a through-thickness transmission setup. Temperature compensation factors were developed to adjust ultrasonic wave speed measurements. The prototype inspection system was demonstrated in a 55 mm conical twin-screw extrusion line.

Tucker, Brian J. (BATTELLE (PACIFIC NW LAB)); Bender, Donald A. (Washington State University)

2003-06-19

370

Detection of Shear and Pressure Waves in Metals by Dynamic Wavelet Fingerprinting in Laser Based Ultrasonics  

Microsoft Academic Search

A dynamic wavelet fingerprinting and visual pattern recognition method has been developed for characterization of Bulk Ultrasonic Waves. Signals are generated in thick stepped samples of aluminum, steel, Inconel and Brass using laser based ultrasonics. The pulsed wave Nd-YAG laser is used to generate the ultrasonic signal in the material and continuous wave He-Ne laser heterodyne interferometry to record surface(out

N. N. Kishore; Aparna Gajendragadkar; Pankaj Gupta; V. Raghuram

2011-01-01

371

Ultrasonic detection of hydrogen attack in low alloy steels  

SciTech Connect

The objective of this study is to predict the early stage of hydrogen attack by means of ultrasonic technique and to correlate the variations in ultrasonic characteristics to the deterioration in mechanical properties, residual hydrogen and microstructural changes (methane bubble formation, decarburization and microcrack formation). On the specimens served at high pressure, high temperature hydrogen atmosphere, non-destructive ultrasonic detection of degradation by hydrogen attack has been performed. The bottom reflected ultrasonic rf pulses from 2,500 points of 50 square mm area in the specimens were collected as digitized rf waves through 100 MHz A/D converter. The variation in wave characteristics resulted from the dispersion of materials can be revealed in the power spectrum of traversed wave in frequency domain and can be defined as characteristic feature values such as center frequency, peak frequency, moment and skewness of Spectrums. Variation in the ultrasonic ``signature`` in time domain and frequency domain given by spectrum analysis due to hydrogen attack has been examined. Based on the knowledge that cavitation in material affects ultrasonic attenuation and velocity, frequency dependent ultrasonic attenuation and velocity have been examined to obtain the size and the number of cavities by using multiple scattering theories and the results have been ascertained by metallographic observations. The results obtained demonstrate that the measurements of frequency dependent ultrasonic attenuation and velocity have a strong potential to quantitative predictions of the methane bubble formation.

Suetsugu, J.; Imanaka, T. [Non-Destructive Inspection Co., Ltd., Osaka (Japan)

1995-08-01

372

High resolution in situ ultrasonic corrosion monitor  

DOEpatents

An ultrasonic corrosion monitor is provided which produces an in situ measurement of the amount of corrosion of a monitoring zone or zones of an elongate probe placed in the corrosive environment. A monitoring zone is preferably formed between the end of the probe and the junction of the zone with a lead-in portion of the probe. Ultrasonic pulses are applied to the probe and a determination made of the time interval between pulses reflected from the end of the probe and the junction referred to, both when the probe is uncorroded and while it is corroding. Corresponding electrical signals are produced and a value for the normalized transit time delay derived from these time interval measurements is used to calculate the amount of corrosion.

Grossman, R.J.

1984-01-10

373

High resolution in situ ultrasonic corrosion monitor  

DOEpatents

An ultrasonic corrosion monitor is provided which produces an in situ measurement of the amount of corrosion of a monitoring zone or zones of an elongate probe placed in the corrosive environment. A monitoring zone is preferably formed between the end of the probe and the junction of the zone with a lead-in portion of the probe. Ultrasonic pulses are applied to the probe and a determination made of the time interval between pulses reflected from the end of the probe and the junction referred to, both when the probe is uncorroded and while it is corroding. Corresponding electrical signals are produced and a value for the normalized transit time delay derived from these time interval measurements is used to calculate the amount of corrosion.

Grossman, Robert J. (Schenectady, NY)

1985-01-01

374

Design of piezocomposites for ultrasonic transducers  

Microsoft Academic Search

1–3 piezoelectric-rod\\/passive-matrix composites offer advantages over the conventional piezoceramics and piezopolymers for the pulse-echo transducers used in medical ultrasonic imaging. Their benefits include high electromechanical coupling, acoustic impedance close to that of tissue, a wide range of dielectric constants, low dielectric and mechanical losses, an adjustable sound speed, low coupling to spurious oscillations, ease of subdividing into acoustically isolated array

Wallace Arden Smith; Avner A. Shaulov; B. A. Auld

1989-01-01

375

Electrical pulse generator  

DOEpatents

A technique for generating high-voltage, wide dynamic range, shaped electrical pulses in the nanosecond range. Two transmission lines are coupled together by resistive elements distributed along the length of the lines. The conductance of each coupling resistive element as a function of its position along the line is selected to produce the desired pulse shape in the output line when an easily produced pulse, such as a step function pulse, is applied to the input line.

Norris, Neil J. (Santa Barbara, CA)

1979-01-01

376

An Ultrasonic Study of the Area of Contact between Stationary and Sliding Surfaces  

Microsoft Academic Search

This paper describes a novel attempt to determine quantitatively the area of contact between stationary and sliding contacts by means of an ultrasonic technique. The basic idea is to generate an ultrasonic wave in one body and measure the impulse passing into the second body through the interface. Analysis shows that the transmitted pulse depends on the elastic stiffness of

K. Kendall; D. Tabor

1971-01-01

377

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

Microsoft Academic Search

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

Jean-Louis Thomas; Mathias A. Fink

1996-01-01

378

Apparatus for generating a focusable and scannable ultrasonic beam for non destructive examination  

Microsoft Academic Search

An apparatus for generating a focusable and scannable ultrasonic beam for use in nondestructive internal examination of an object. In one embodiment an optical mask modifies a pulsed light beam to form an optical zone pattern. The zone pattern is imaged on the surface of an optically absorbing thermoelastic layer in contact with a propagation medium. An ultrasonic beam is

R. J. von Gutfeld; S. S. Wang

1985-01-01

379

An ultrasonic method for studying elastic moduli as a function of temperature  

NASA Technical Reports Server (NTRS)

Ultrasonic method is used to determine the elastic moduli of materials used in components of high-temperature nuclear reactors. An ultrasonic, pulse-echo technique determines the velocity of sound waves propogating in a heated region of rod-shaped specimens. From these velocities, the elastic moduli are calculated.

Peterson, R. G.

1969-01-01

380

Pulse-Code Modulation Systems  

Microsoft Academic Search

Following a review of the principles of pulsed transmission of information, the method of pulse-code modulation (PCM) is discussed. Two different experimental systems for performing this function are described.

A. J. Oxford

1953-01-01

381

Ultrasonic techniques for imaging and measurements in molten aluminum.  

PubMed

In order to achieve net shape forming, processing of aluminum (Al) in the molten state is often necessary. However, few sensors and techniques have been reported in the literature due to difficulties associated with molten Al, such as high temperature, corrosiveness, and opaqueness. In this paper, development of ultrasonic techniques for imaging and measurements in molten Al using buffer rods operated at 10 MHz is presented. The probing end of the buffer rod, having a flat surface or an ultrasonic lens, was immersed into molten Al while the other end with an ultrasonic transducer was air-cooled to room temperature. An ultrasonic image of a character "N", engraved on a stainless steel plate immersed in molten Al, and its corrosion have been observed at 780 degrees C using the focused probe in ultrasonic pulse-echo mode. Because cleanliness of molten Al is crucial for part manufacturing and recycling in Al processing, inclusion detection experiments also were carried out using the nonfocused probe in pitch-catch and pulse-echo modes. Backscattered ultrasonic signals from manually added silicon carbide particles, with an average diameter of 50 microm, in molten Al have been successfully observed at 780 degrees C. For optimal image quality, the spatial resolution of the focused probe was crucial, and the high signal-to-noise ratio of the nonfocused probe was the prime factor responsible for the inclusion detection sensitivity using backscattered ultrasonic signals. In addition, it was found that ultrasound could provide an alternative method for evaluating the degree of wetting between a solid material and a molten metal. Our experimental results showed that there was no ultrasonic coupling at the interface between an alumina rod and molten Al up to 1000 degrees C; therefore, no wetting existed at this interface. Also because ultrasonic velocity in alumina is temperature dependent, this rod proved to be able to be used as an in-line temperature monitoring sensor under 1000 degrees C in molten Al. PMID:14761042

Ono, Yuu; Moisan, Jean-François; Jen, Cheng-Kuei

2003-12-01

382

Picosecond ultrasonic measurements using an optical mask.  

PubMed

In this paper we describe results obtained using a variation of the picosecond ultrasonics technique. We place a transparent optical mask very close to the surface of the sample. The lower surface of the mask has a series of grooves to produce a variation of the intensity of the pump and probe light pulses across the surface of the sample. Because the light intensity varies with position, the application of the pump light pulse can generate surface acoustic waves with a wavelength equal to the period of the mask. We report results obtained in this way and discuss the possible practical applications of this new approach. PMID:24767174

Miao, Q; Liu, L-W; Grimsley, T J; Nurmikko, A V; Maris, H J

2015-02-01

383

Fig. 1. Interface buffer connected to OPS network. Packets are first copied to the buffer, then injected into the network. If network transmission is successful, a control signaling ack is sent to the buffer and the copy is discarded. If no ack pulse is r  

E-print Network

to the buffer and the copy is discarded. If no ack pulse is received, the packet is retransmitted in the next, it is discarded from the queue. In the case of an unsuccessful message transmission, the input buffer can

Bergman, Keren

384

Ultrasonic Communication Project, Phase 1, FY1999  

SciTech Connect

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.

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

2000-06-01

385

Proposal for an Ultrasonic Tool to Monitor the Osseointegration of Dental Implants  

PubMed Central

The longevity of dental implants depends on osseointegration, which provides load-bearing capacity without putting the prosthesis at risk from micromotions at the implant-bone interface. This research involved an analysis of the viability of an ultrasonic evaluation tool to quantify osseointegration. Ultrasonic transmission is directly dependent on the difference between the acoustic impedance of materials in intimate contact with each other. The closer their acoustic impedances the more intense their transmission. Therefore, an analysis of the ultrasonic echoes would presumably allow for a quantitative evaluation of the bone tissue that has grown into the pores of the implant. In addition, the literature reports that bone fracture healing can be accelerated by the application of a controlled low-amplitude mechanical stimulus on the site of the lesion. In fact, acoustic pressure waves of low-intensity pulsed ultrasound are reportedly a secure technique for promoting mechanical stimulus without impairing the healing process. Many experimental and clinical trials have confirmed that daily transcutaneous ultrasound applications on the injured site are beneficial to the enhancement of fractured bone. This proposal aims to bring together the characteristics of ultrasound propagation and the positive effect of ultrasound on bone growth into a single tool that quantitatively monitors the evolution of the osseointegration process. The viability of a device with these features was investigated through simulations and experimentally. The initial simulations were conducted to explore the influence of waveguide shapes on the tool's sensitivity to changes in the implant supporting media. The waveguides were designed in two parts, one consisting of a screw-shaped part to attach to the implant and the other a conical or step-shaped part to which the ultrasonic source was fixed in the first simulations. The step-shaped waveguide proved to be the more sensitive; intermediate stages of the osseointegration process were simulated and experiments were conducted with the step-shaped aluminum waveguide attached to a cylindrical aluminum nut embedded at different depths, so that the results obtained were only due to lateral attachment of the parts. These devices indicated that the transmission of ultrasound through the lateral surface of the implant by dilatational waves could render this tool suitable for monitoring the osseointegration of dental implants.

de Almeida, Marina Storani; Maciel, Carlos Dias; Pereira, José Carlos

2007-01-01

386

646 ULTRASONIC PHYSICAL MECHANISMS AND CHEMICAL EFFECTS ULTRASONIC PHYSICAL MECHANISMS  

E-print Network

646 ULTRASONIC PHYSICAL MECHANISMS AND CHEMICAL EFFECTS ULTRASONIC PHYSICAL MECHANISMS AND CHEMICAL. Copyright # 1999 John Wiley & Sons, Inc. #12;ULTRASONIC PHYSICAL MECHANISMS AND CHEMICAL EFFECTS 647 sion. In addition, high- velocity interparticle collisions will occur during ultrasonic ir- can be extremely violent

Suslick, Kenneth S.

387

Investigation of inductively coupled ultrasonic transducer system for NDE.  

PubMed

Inductive coupling offers a simple solution to wirelessly probe ultrasonic transducers. This paper investigates the theory and feasibility of such an inductively coupled transducer system in the context of nondestructive evaluation (NDE) applications. The noncontact interface is based on electromagnetic coupling between three coils; one of the coils is physically connected to the transducer, the other two are in a separate probing unit, where they are connected to the transmit and receive channels of the instrumentation. The complete system is modeled as a three-port network with the measured impedance of a bonded piezoelectric ceramic disc representing a sensor attached to an arbitrary solid substrate. The developed transmission line model is a function of the physical parameters of the electromagnetic system, such as the number of turns and diameter of each coil, and their separation. This model provides immediate predictions of electrical input impedance and pulse-echo response. The model has been validated experimentally and a sensitivity analysis of the input parameters performed. This has enabled optimization of the various parameters. Inductively coupled transducer systems have been built for both bulk and guided wave examples. By using chirped excitation and baseline subtraction, inspection distance of up to 700 mm is achieved in single-shot, guided-wave pulse-echo mode measurements with a 5 mm separation between the probing coils and transducer coil on an aluminum plate structure. In the bulk wave example, a delamination in an 8.9-mm-thick carbon fiber composite specimen is successfully identified from the changes in the arrival time of a reflected pulse. PMID:25004474

Zhong, Cheng Huan; Croxford, Anthony J; Wilcox, Paul D

2013-06-01

388

Review on ultrasonic machining  

Microsoft Academic Search

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

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

1998-01-01

389

Ultrasonic corona sensor study  

NASA Technical Reports Server (NTRS)

The overall objective of this program is to determine the feasibility of using ultrasonic (above 20 kHz) corona detection techniques to detect low order (non-arcing) coronas in varying degrees of vacuum within large high vacuum test chambers, and to design, fabricate, and deliver a prototype ultrasonic corona sensor.

Harrold, R. T.

1976-01-01

390

Ultrasonic/Sonic Anchor  

NASA Technical Reports Server (NTRS)

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"

Bar-Cohen, Yoseph; Sherrit, Stewart

2009-01-01

391

Monitoring the setting of concrete by measuring the change in ultrasonic p-wave energy  

Microsoft Academic Search

Research on ultrasonic methods to monitor the setting of concrete has mainly focussed on the wave velocity as a useful quantity. To investigate the application of also the wave energy as a parameter, the ultrasonic wave transmission technique was performed on several concrete and mortar samples in which increasing amounts of the Portland cement was replaced by blast-furnace slag or

Nicolas ROBEYST; Nele DE BELIE

392

Proposal of 3 dimension imaginary space touch panel using ultrasonic sensors  

Microsoft Academic Search

It proposes three dimension virtual space touch panel that can be intuitively operated by moving the finger. In the present study, the ultrasonic wave transmission sensor is installed in the finger as a pointer, and four ultrasonic wave reception sensors are put on the floor. Then, three dimension coordinates of the pointer are specified by measuring the distance of each

R. Yasunaka; Y. Kitazono; Lifeng Zhang; S. Serikawa; S. Nakashima

2010-01-01

393

Automated Detection of Cracked Railway Axle Journals Using an Ultrasonic Phased Array Technique  

E-print Network

-coupled experiments are demonstrated: 1) the line-source air-coupled ultrasonic array sensors in through-transmission mode, 2) the point-source air-coupled ultrasonic generation using Rayleigh waves, and 3) the laser array detector on a steel plate. A complete air...

Baik, Jaeyong

2014-06-27

394

Ultrasonic diagnosing apparatus  

SciTech Connect

An ultrasonic diagnosing apparatus displays a modified c-mode image of the target of an object to be diagnosed by mechanically moving an ultrasonic probe around the target portion while electronically driving the probe to scan the target. The ultrasonic diagnosing apparatus comprises a circuit for setting a desired cross-section to be diagnosed in the b-mode image of the target while observing said b-mode image, a memory for storing the data of the cross-section set by the cross-section setting circuit, a function generator for converting the position data into a function signal for controlling the scanning of the target and the processing of an ultrasonic echo signal reflected therefrom, a signal processing device for processing the ultrasonic echo signal under control of the function signal, and a display means for displaying a modified c-mode image of the target.

Uranishi, M.

1980-12-23

395

Pulse stretcher  

DOEpatents

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).

Horton, James A. (Livermore, CA)

1994-01-01

396

Ultrasonic evaluation of the physical and mechanical properties of granites.  

PubMed

Masonry is the oldest building material that survived until today, being used all over the world and being present in the most impressive historical structures as an evidence of spirit of enterprise of ancient cultures. Conservation, rehabilitation and strengthening of the built heritage and protection of human lives are clear demands of modern societies. In this process, the use of nondestructive methods has become much common in the diagnosis of structural integrity of masonry elements. With respect to the evaluation of the stone condition, the ultrasonic pulse velocity is a simple and economical tool. Thus, the central issue of the present paper concerns the evaluation of the suitability of the ultrasonic pulse velocity method for describing the mechanical and physical properties of granites (range size between 0.1-4.0 mm and 0.3-16.5 mm) and for the assessment of its weathering state. The mechanical properties encompass the compressive and tensile strength and modulus of elasticity, and the physical properties include the density and porosity. For this purpose, measurements of the longitudinal ultrasonic pulse velocity with distinct natural frequency of the transducers were carried out on specimens with different size and shape. A discussion of the factors that induce variations on the ultrasonic velocity is also provided. Additionally, statistical correlations between ultrasonic pulse velocity and mechanical and physical properties of granites are presented and discussed. The major output of the work is the confirmation that ultrasonic pulse velocity can be effectively used as a simple and economical nondestructive method for a preliminary prediction of mechanical and physical properties, as well as a tool for the assessment of the weathering changes of granites that occur during the serviceable life. This is of much interest due to the usual difficulties in removing specimens for mechanical characterization. PMID:18471849

Vasconcelos, G; Lourenço, P B; Alves, C A S; Pamplona, J

2008-09-01

397

Hadamard multiplexing in laser ultrasonics.  

PubMed

In state-of-the-art laser ultrasonics (LU), the signal-to-noise ratio (SNR) is limited by the shot noise of the detected laser radiation. Further improving the SNR then requires averaging multiple signals or increasing generation and/or detection laser intensities. The former strategy is time consuming and the latter leads to surface damages. For signal-independent limiting noises, Hadamard multiplexing increases the SNR by averaging multiple signals in parallel using a single detector. Here we consider the use of Hadamard multiplexing in LU for the non-contact ultrasonic inspection of materials. By using 31 element Hadamard masks to modulate the spatial intensity distribution of the generation laser beam, the measured SNR is improved by a factor 2.8, in good agreement with the expected multiplexing or Fellgett advantage. In contrast to many other applications of Hadamard multiplexing, the SNR is improved for shot-noise-limited measurements since the shot noise level is independent of the signal in LU. The Hadamard multiplexing of the detection laser beam is also considered but can only lead to a throughput or Jacquinot advantage. However, for pulse-echo LU, the Hadamard multiplexing of both generation and detection laser beams allows using the synthetic aperture focusing technique (SAFT). PMID:23187397

Rousseau, Guy; Blouin, Alain

2012-11-01

398

Detonator comprising a nonlinear transmission line  

DOEpatents

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.

Elizondo-Decanini, Juan M

2014-12-30

399

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

SciTech Connect

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.

TL Murphy

2006-02-16

400

Image measurement technique on vibration amplitude of ultrasonic horn  

NASA Astrophysics Data System (ADS)

The paper proposes a method to measure vibration amplitude of ultrasonic horn which is a very important component in the spindle for micro-electrical-chemical discharging machining. The method of image measuring amplitude on high frequency vibration is introduced. Non-contact measurement system based on vision technology is constructed. High precision location algorithm on image centroid, quadratic location algorithm, is presented to find the center of little light spot. Measurement experiments have been done to show the effect of image measurement technique on vibration amplitude of ultrasonic horn. In the experiments, precise calibration of the vision system is implemented using a normal graticule to obtain the scale factor between image pixel and real distance. The vibration amplitude of ultrasonic horn is changed by modifying the voltage amplitude of pulse power supply. The image of feature on ultrasonic horn is captured and image processing is carried out. The vibration amplitudes are got at different voltages.

Zhang, Yong-bin; Wu, Zhi-qun; Zhu, Jian-ping; He, Jian-guo; Liu, Guang-min

2013-10-01

401

Three dimensional ultrasonic imaging  

SciTech Connect

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.

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

1993-03-01

402

LASER COMPONENTS AND DEVICES: Use of an LC transmission line to supply the discharge in a pulsed electron-beam-controlled CO laser  

Microsoft Academic Search

The first description is given of an electron-beam-controlled (EBC) CO laser with the main discharge supplied from an LC transmission line. This line significantly weakened superelastic collisions of the discharge electrons with the vibrationally excited CO molecules. The time dependences of the output radiation power of an EBC CO laser supplied from an LC transmission line were different from the

V. S. Kazakevich; K. V. Morozov; A. L. Petrov; G. N. Popkov

1994-01-01

403

Ultrasonic Imaging System  

NASA Technical Reports Server (NTRS)

An imaging system is described which can be used to either passively search for sources of ultrasonics or as an active phase imaging system. which can image fires. gas leaks, or air temperature gradients. This system uses an array of ultrasonic receivers coupled to an ultrasound collector or lens to provide an electronic image of the ultrasound intensity in a selected angular region of space. A system is described which includes a video camera to provide a visual reference to a region being examined for ultrasonic signals.

Youngquist, Robert C. (Inventor); Moerk, Steven (Inventor)

1999-01-01

404

Ultrasonic liquid level detector  

DOEpatents

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.

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

2010-09-28

405

Numerical simulation of laser ultrasonics for detecting subsurface lateral defects  

Microsoft Academic Search

Non-contact and nondestructive monitoring of subsurface defects are urgently required especially in the line production of such products. In this paper a two-dimensional plane stress finite element model with absorbing boundary condition has been developed to investigate the ultrasonic wave generated by nanosecond pulsed laser propagation in two-layer material. The pulsed laser is assumed to be transient heat source, and

Jianfei Guan; Zhonghua Shen; Baiqiang Xu; Jian Lu; Xiaowu Ni

2005-01-01

406

Photoconductive circuit element pulse generator  

DOEpatents

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.

Rauscher, Christen (Alexandria, VA)

1989-01-01

407

Investigation of capacitively coupled ultrasonic transducer system for nondestructive evaluation.  

PubMed

Capacitive coupling offers a simple solution to wirelessly probe ultrasonic transducers. This paper investigates the theory, feasibility, and optimization of such a capacitively coupled transducer system (CCTS) in the context of nondestructive evaluation (NDE) applications. The noncontact interface relies on an electric field formed between four metal plates-two plates are physically connected to the electrodes of a transducer, the other two are in a separate probing unit connected to the transmit/receive channel of the instrumentation. The complete system is modeled as an electric network with the measured impedance of a bonded piezoelectric ceramic disc representing a transducer attached to an arbitrary solid substrate. A transmission line model is developed which is a function of the physical parameters of the capacitively coupled system, such as the permittivity of the material between the plates, the size of the metal plates, and their relative positions. This model provides immediate prediction of electric input impedance, pulse-echo response, and the effect of plate misalignment. The model has been validated experimentally and has enabled optimization of the various parameters. It is shown that placing a tuning inductor and series resistor on the transmitting side of the circuit can significantly improve the system performance in terms of the signal-to-crosstalk ratio. Practically, bulk-wave CCTSs have been built and demonstrated for underwater and through-composite testing. It has been found that electrical conduction in the media between the plates limits their applications. PMID:24297024

Zhong, Cheng Huan; Wilcox, Paul D; Croxford, Anthony J

2013-12-01

408

Testing Results of Magnetostrictive Ultrasonic Sensor Cables for Signal Loss  

SciTech Connect

The purpose of this test was to determine the signal strength and resolution losses of a magnetostrictive ultrasonic system with an extended signal cable. The cable of interest carries electrical signals between the pulse generator/receiver and the magnetostrictive transducer. It was desired to determine the loss introduced by different lengths of the signal cable (6', 100', and 200').

JT Evans

2005-05-01

409

A neural network architecture for ultrasonic nondestructive testing  

Microsoft Academic Search

The application of neural networks for detecting defects in materials consisting of dense microstructures using ultrasonic pulse-echo systems is discussed. The motivation for this work is the desire to detect defects modeled by small complex scattering centers. To preserve signal features useful for defect detection, minimal preprocessing is performed on the data presented to the neural network. Modifications to the

Y. Guez; K. D. Donohue; N. M. Bilgutay

1991-01-01

410

Error-eliminating rapid ultrasonic firing  

DOEpatents

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.

Borenstein, J.; Koren, Y.

1993-08-24

411

Error-eliminating rapid ultrasonic firing  

DOEpatents

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.

Borenstein, Johann (Ann Arbor, MI); Koren, Yoram (Ann Arbor, MI)

1993-08-24

412

A contact method for the assessment of ultrasonic velocity and broadband attenuation in cortical and cancellous bone  

Microsoft Academic Search

A portable system using a direct contact method for the measurement of ultrasonic velocity and broadband attenuation in bone is described (contact ultrasonic bone analyser, CUBA). Soft-tissue compensation is performed using an ultrasonic pulse-echo technique. CUBA has been successfully validated using reference materials, the precision of velocity and broadband attenuation measurements being typically 0.2% and 0.5% respectively. The clinical reproducibility

C M Langton; A V Ali; C M Riggs; G P Evans; W Bonfield

1990-01-01

413

Integrated ultrasonic and petrographical characterization of carbonate building materials  

NASA Astrophysics Data System (ADS)

This paper presents the application of non-destructive ultrasonic techniques in evaluating the conservation state and quality of monumental carbonate building materials. Ultrasonic methods are very effective in detecting the elastic characteristics of the materials and thus their mechanical behaviour. They are non-destructive and effective both for site and laboratory tests, though it should be pointed out that ultrasonic data interpretation is extremely complex, since elastic wave velocity heavily depends on moisture, heterogeneity, porosity and other physical properties of the materials. In our study, considering both the nature of the building materials and the constructive types of the investigated monuments, the ultrasonic investigation was carried out in low frequency ultrasonic range (24 kHz - 54 kHz) with the aim of detecting damages and degradation zones and assessing the alterability of the investigated stones by studying the propagation of the longitudinal ultrasonic pulses. In fact alterations in the materials generally cause a decrease in longitudinal pulse velocity values. Therefore starting from longitudinal velocity values the elasto-mechanical behaviour of the stone materials can be deduced. To this aim empirical and effective relations between longitudinal velocity and mechanical properties of the rocks can be used, by transferring the fundamental concepts of the studies of reservoir rocks in the framework of hydrocarbon research to the diagnostic process on stone materials. The ultrasonic measurements were performed both in laboratory and in situ using the Portable Ultrasonic Non-Destructive Digital Indicating Tester (PUNDIT) by C.N.S. Electronics LTD. A number of experimental sessions were carried out choosing different modalities of data acquisition. On the basis of the results of the laboratory measurements, an in situ ultrasonic survey on significant monuments, have been carried out. The ultrasonic measurements were integrated by a petrographical and petrophysical study of the investigated stone materials to correlate their petrographical-petrophysical features with the elastic ones. From this integrated study results that the modifications in the elasto-mechanical and petrographical-petrophysical features of the investigated carbonate materials are the main causes which reduce their quality as building materials. The use of the ultrasonic method integrated with information on petrography and petrophysics of the rocks has been successful to assess the rock quality and better understanding their alteration process. Acknowledgments: This work was financially supported by Sardinian Local Administration (RAS - LR 7 August 2007, n.7, Promotion of Scientific Research and Innovation in Sardinia - Italy, Responsible Scientist: S. Fais).

Ligas, Paola; Fais, Silvana; Cuccuru, Francesco

2014-05-01

414

Experimental and simulated ultrasonic characterization of complex damage in fused silica.  

PubMed

The growth of a laser-induced, surface damage site in a fused silica window was monitored by the ultrasonic pulse-echo technique. The laser damage was grown using 12-ns pulses of 1.053-microm wavelength light at a fluence of approximately 27 J/cm2. The ultrasonic data were acquired after each pulse of the laser beam for 19 pulses. In addition, optical images of the surface and subsurface damage shape were recorded after each pulse of the laser. The ultrasonic signal amplitude exhibited variations with the damage size, which were attributed to the subsurface morphology of the damage site. A mechanism for the observed ultrasonic data based on the interaction of the ultrasound with cracks radiating from the damage site was tested using two-dimensional numerical simulations. The simulated results exhibit qualitatively similar characteristics to the experimental data and demonstrate the usefulness of numerical simulation as an aid for ultrasonic signal interpretation. The observed sensitivity to subsurface morphology makes the ultrasonic methodology a promising tool for monitoring laser damage in large aperture laser optics used in fusion energy research. PMID:11885682

Martin, L Peter; Chambers, David H; Thomas, Graham H

2002-02-01

415

Differential pulse code modulation  

NASA Technical Reports Server (NTRS)

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.

Herman, C. F. (inventor)

1976-01-01

416

Matrix techniques for modeling ultrasonic waves in multilayered media  

Microsoft Academic Search

Research into ultrasonic NDE techniques for the inspection of multilayered structures relies strongly on the use of modeling tools which calculate dispersion curves and reflection and transmission spectra. These predictions are essential to enable the best inspection strategies to be identified and their sensitivities to be evaluated. General purpose multilayer modeling tools may be developed from a number of matrix

Michael J. S. Lowe

1995-01-01

417

Ultrasonic scattering from imperfect interfaces: A quasi-static model  

Microsoft Academic Search

A quasi-static model for the ultrasonic transmission and reflection at imperfect interfaces is developed. The interface is represented by a distributed spring, determined by the change in static compliance of the medium with respect to one with a perfect interface, and a distributed mass, representing excess mass at the interface. Comparison of the model predictions to exact solutions for two

Jai-Man Baik; R. Bruce Thompson

1984-01-01

418

Ultrasonic annular array system for detecting tissue motion  

NASA Astrophysics Data System (ADS)

We are developing ultrasonic strain-flow imaging instrumentation specifically to facilitate improved diagnosis of breast tissue disease. An 8-ring, 30-mm-diameter, f/1.5, spherically focused annular array was built to generate broadband, 10 MHz pulses at a rate up to 10 KHz. This transducer uses the synthetic receive aperture technique to record echoes while being mechanically steered by a linear positioner under microprocessor control. Specifically, a 200Vpp signal is applied to all rings simultaneously on transmission. Individual rings are then sequentially multiplexed to a receiver. Echoes are dynamically delayed and coherently summed off-line to adjust the receive focus and extend the depth of focus. The aperture material is a 1-3 composite built by Imasonic SA, Besancon, France. One advantage of the design is that it provides a well-focused axisymmetric beam with an improved depth of focus to acquire images at a high spatial resolution. Pulse-echo simulations of our array using the Field II software package show a -6dB beam width at 0.24 mm and -6dB depth of focus at 2.4 mm that can be extended to 3.2 mm with dynamic focusing. These simulations agree with later measurements performed on the transducer. Our flexible aperture design allows us to drop outer rings significantly increasing the depth of focus (up to 56% increase by dropping 3 rings) with a tolerable decrease in lateral resolution (27% increase in beam width). We expect that our probe will enable us to examine detailed biological processes throughout the malignant growth period of a tumor tissue that exhibits elastic anisotropy, thus providing high resolution ultrasound images over an extended and adjustable depth of field.

Mhanna, Hisham; Trummer, Birget; Kargel, Christian M.; Insana, Michael F.

2002-04-01

419

Cross-sectional distributions of gas and solid holdups in slurry bubble column investigated by ultrasonic computed tomography  

Microsoft Academic Search

A brief review on recently developed non-invasive techniques for gas–liquid and gas–liquid–solid systems is presented first. The ultrasonic computed tomography (UCT) developed for measuring the time-averaged cross-sectional distributions of gas and solid holdups in a slurry bubble column is then described. The ultrasonic tomography is a coupling of the earlier developed transmission-mode ultrasonic technique with two-parameter sensing (the energy attenuation

M Warsito; M. Ohkawa; N. Kawata; S. Uchida

1999-01-01

420

Cluster-enhanced sparse approximation of overlapping ultrasonic echoes.  

PubMed

Ultrasonic pulse-echo methods have been used extensively in non-destructive testing of layered structures. In acoustic measurements on thin layers, the resulting echoes from two successive interfaces overlap in time, making it difficult to assess the individual echo parameters. Over the last decade sparse approximation methods have been extensively used to address this issue. These methods employ a large dictionary of elementary functions (atoms) and attempt to select the smallest subset of atoms (sparsest approximation) that represent the ultrasonic signal accurately. In this paper we propose the cluster-enhanced sparse approximation (CESA) method for estimating overlapping ultrasonic echoes. CESA is specifically adapted to deal with a large number of signals acquired during an ultrasonic scan. It incorporates two principal algorithms. The first is a clustering algorithm, which divides a set of signals comprising an ultrasonic scan into groups of signals that can be approximated by the same set of atoms. The second is a two-stage iterative algorithm, which alternates between update of the atoms associated with each cluster, and re-clustering of the signals according to the updated atoms. Because CESA operates on clusters of signals, it achieves improved results in terms of approximation error and computation time compared with conventional sparse methods, which operate on each signal separately. The superior ability of CESA to approximate highly overlapping ultrasonic echoes is demonstrated through simulation and experiments on adhesively bonded structures. PMID:25643086

Mor, Etai; Aladjem, Mayer; Azoulay, Amnon

2015-02-01

421

Solid state stepped transmission line transformer for spark gap triggering  

Microsoft Academic Search

Spark gap switched transmission line pulse generators can achieve faster switching by overvolting the spark gap with high amplitude nanosecond pulses. A solid-state driven stepped transmission line transformer (TLT) is presented for triggering spark gaps in the overvoltage mode. The spark gap trigger source is simple and compact for integration with pulse generator systems. A totem pole MOSFET pulse source

Matthew Behrend; Andras Kuthi; Martin Gundersen

2003-01-01

422

Randomized comparison of ultrasonic aspiration versus conventional electrocautery for dissection of the human internal thoracic artery.  

PubMed

The most common technique currently employed to harvest the internal thoracic artery for coronary artery bypass grafting is conventional electrocautery. This study compared an alternative method, electrocautery with an ultrasonic aspirator, for harvesting the internal thoracic artery. Patients were randomly assigned to one of six experimental groups (conventional electrocautery, ultrasonic aspirator at settings of 60%, 80%, and 100% power output, and ultrasonic aspirator in 100% CAVI-Pulse modes 1 and 3). Ring segments of internal thoracic artery were studied in an organ bath. Contraction responses were elicited with 123 mmol/L potassium physiologic salt solution, KPSS, KPSS solution containing noradrenaline, and a cumulative noradrenaline dose-contraction curve. Relaxation studies were performed with the vasodilators acetylcholine, bradykinin, and sodium nitroprusside. Forty percent of the electrocauterized vessels were traumatized or damaged and failed to respond to contractile stimuli, whereas only 10% of the vessels in ultrasonic aspirator groups 60%, 80%, and 100% failed to respond. All vessels in the group harvested by ultrasonic aspirator in 100% CAVI-Pulse mode 1 responded, whereas 20% of the vessels in the group harvested by ultrasonic aspirator in 100% CAVI-Pulse mode 3 failed to respond. All settings of electrocautery with an ultrasonic aspirator produced a greater contractile response to KPSS and noradrenaline. Acetylcholine and sodium nitroprusside produced similar relaxations in all groups, but the bradykinin responses were significantly improved in all groups undergoing 100% electrocautery with an ultrasonic aspirator. These results suggest that 100% electrocautery with an ultrasonic aspirator, particularly in 100% CAVI-Pulse mode 1, resulted in less damage and trauma than conventional electrocautery during harvesting of the internal thoracic artery. PMID:8642820

Blake, K L; Watt, P A; Smith, J M; De Souza, A C; Spyt, T J; Thurston, H

1996-06-01

423

ULTRASOUND PULSE-ECHO IMAGING USING THE SPLIT-STEP FOURIER PROPAGATOR  

SciTech Connect

Ultrasonic reflection imaging has the potential to produce higher image resolution than transmission tomography, but imaging resolution and quality still need to be further improved for early cancer detection and diagnosis. We present an ultrasound reflection image reconstruction method using the split-step Fourier propagator. It is based on recursive inward continuation of ultrasonic wavefields in the frequency-space and frequency-wavenumber domains. The inward continuation within each extrapolation interval consists of two steps. In the first step, a phase-shift term is applied to the data in the frequency-wavenumber domain for propagation in a reference medium. The second step consists of applying another phase-shift term to data in the frequency-space domain to approximately compensate for ultrasonic scattering effects of heterogeneities within the breast. We use synthetic ultrasound pulse-echo data recorded around a ring for heterogeneous, computer-generated numerical breast phantoms to study the imaging capability of the method. The phantoms are derived from an experimental breast phantom and a sound-speed tomography image of an in-vivo ultrasound breast data collected usi ng a ring array. The heterogeneous sound-speed models used for pulse-echo imaging are obtained using a computationally efficient, first-arrival-time (time-of-flight) transmission tomography method. Our studies demonstrate that reflection image reconstruction using the split-step Fourier propagator with heterogeneous sound-speed models significantly improves image quality and resolution. We also numerically verify the spatial sampling criterion of wavefields for a ring transducer array.

HUANG, LIANJIE [Los Alamos National Laboratory; QUAN, YOULI [Los Alamos National Laboratory

2007-01-31

424

Laser ultrasonic propagation imaging method in the frequency domain based on wavelet transformation  

NASA Astrophysics Data System (ADS)

A wavelet-transformed ultrasonic propagation imaging method capable of ultrasonic propagation imaging in the frequency domain was developed and applied as a new structural damage or flaw visualization algorithm. Since the wavelet-transformed ultrasonic propagation imaging method has strong frequency selectivity, it can visualize the propagation of ultrasonic waves of a specific frequency (for example, to isolate ultrasonic mode of interest and a damage-related ultrasonic wave). The strong frequency selectivity of the wavelet-transformed ultrasonic propagation imaging method was demonstrated, isolating only the zeroth-order asymmetrical mode of the fundamental Lamb wave modes in an anisotropic carbon fiber-reinforced plastic plate with a thickness of 5 mm. The wavelet-transformed ultrasonic propagation imaging method can also convert a complex time domain multiple wavefield into a simple frequency domain single wavefield. This feature enables easy interpretation of the results, and facilitates the precise evaluation of the location and size of structural damage or flaws. We demonstrated this capability by detecting a disbond in a sandwich structure made of Al-alloy skins and a foam core. A disbond with a diameter of 20 mm, which is representative of a common manufacturing flaw, was successfully detected, localized, and evaluated. Since a method to determine the allowable maximum pulse repetition frequency depending on target materials and structures was found by investigating the residual wave caused from the previous laser impinging, our laser ultrasonic system can scan rapidly the target with an optimal pulse repetition rate. In addition, the proposed wavelet-transformed ultrasonic propagation imaging method can visualize damage or flaw without the need for reference data from the intact state of the structure. Hence, we propose the wavelet-transformed ultrasonic propagation imaging approach for automatic inspection of in-service engineering structures, or in-process quality inspection in manufacturing.

Lee, Jung-Ryul; Ciang Chia, Chen; Jin Shin, Hye; Park, Chan-Yik; Jin Yoon, Dong

2011-01-01

425

Ultrasonic wave techniques and characterization of filled elastomers and biodegradable polymers  

NASA Astrophysics Data System (ADS)

Ultrasonic wave technique is an excellent method for non-destructive testing and for the monitoring of polymer curing, fatigue damage and polymer transition. It is also a potentially effective tool to be applied in the characterization of high frequency viscoelastic properties of polymers. This research represents the effort to improve and further develop ultrasonic wave techniques and extend its applications to new material evaluation areas. The work is presented as followings: In chapter 1, the fundamental wave propagation theories and characterization of the viscoelastic properties of materials by acoustic parameters were briefly reviewed. In chapter 2, the effects of carbon black filler on the elastomers were studied by the longitudinal wave pulse-echo technique. It is found that the enhanced pulse-echo technique is able to characterize the effects of polymer base, filler loading level, type as well as temperature, on the acoustic properties of filled elastomers. In chapter 3, the application of longitudinal wave pulse-echo technique was extended to the monitoring of the degradation process of biodegradable polymers: poly (glycolic acid)(PGA), poly (lactic acid) (PLA) and their copolymer-poly(d,l-lactide-co-glycolide) (PDLLG). It shows that the pulse-echo technique is able to differentiate the effects of polymer structure and preparation method on the degradation behavior of biopolymers. In chapter 4, the Young's modulus, shear modulus, bulk modulus and Poisson ratio of carbon black filled elastomers were determined by the longitudinal wave pulse-echo method and the shear wave through-transmission method. The effects of polymer base, filler loading and dispersion on the elastomers were also studied by the calculated elastic constants. In chapter 5, the effects of carbon black filler on the elastomers were studied by an innovative calibrated longitudinal and shear wave surface impedance technique. The results show that the effects of polymer base, filler loading level and dispersion can be characterized and there is an optimal dispersion time for the mixing process of rubber manufacturing. In the last chapter, an overall conclusion was given regarding the whole theoretical and experimental work in the study.

Wu, Hsueh-Chang

426

Artificial Intelligence Assists Ultrasonic Inspection  

NASA Technical Reports Server (NTRS)

Subtle indications of flaws extracted from ultrasonic waveforms. Ultrasonic-inspection system uses artificial intelligence to help in identification of hidden flaws in electron-beam-welded castings. System involves application of flaw-classification logic to analysis of ultrasonic waveforms.

Schaefer, Lloyd A.; Willenberg, James D.

1992-01-01

427

Non-destructive evaluation of concrete with ultrasonic C-scan and digital image enhancement techniques  

NASA Astrophysics Data System (ADS)

This paper presents the results of Non-Destructive Evaluation (NDE) of concrete slabs using Ultrasonic C-Scan and image-enhancement algorithms for the detection and extraction of damage information from raw data. Two fabricated concrete slabs, one undamaged and the other with three rectangular voids were used for the test. Damage was evaluated by using ultrasonic through transmission C-Scan method. A 500 kHz transducer with pulse rates of 100 Hz to 5000 Hz was investigated to determine the best pulse rate for scanning concrete. The amplitude scan shows accurately the position of the voids present in the damaged concrete with respect to the reference edge. The results also show the inherent in-homogeneity of the concrete slab due to the presence of air pockets that invariably arise during the fabrication. Three statistical filtering techniques (Median, Mean and Gaussian) and one wavelet filtering technique were comparatively evaluated to enhance the quality of the digital image. The results show clearly the presence of the rectangular voids. Median filtering technique was the best in enhancing the image obtained from the C-Scan in terms of removing noise and preserving the details of the defects. Wavelet filtering technique was good in terms of overall noise reduction, but it resulted in loss of details of the defects producing a comparatively blurred image. This technique can be used to determine the quality of concrete at any stage in its working lifecycle thus making it a useful tool in the field of health monitoring of concrete.

Okafor, A. Chukwujekwu; Dutta, Amitabha

2014-02-01

428

Focused high frequency needle transducer for ultrasonic imaging and trapping  

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

429

Measuring the change in ultrasonic p-wave energy transmitted in fresh mortar with additives to monitor the setting  

Microsoft Academic Search

Research on ultrasonic methods to monitor the setting of concrete has mainly focussed on the wave velocity as a useful quantity. To investigate the application of also the wave energy as a parameter, an experimental program was set up to apply the ultrasonic wave transmission technique on several mortar samples containing air entrainer, blast-furnace slag or fly ash causing clearly

Nicolas Robeyst; Christian U. Grosse; Nele De Belie

2009-01-01

430

Ultrasonic/Sonic Jackhammer  

NASA Technical Reports Server (NTRS)

The invention provides a novel jackhammer that utilizes ultrasonic and/or sonic vibrations as source of power. It is easy to operate and does not require extensive training, requiring substantially less physical capabilities from the user and thereby increasing the pool of potential operators. An important safety benefit is that it does not fracture resilient or compliant materials such as cable channels and conduits, tubing, plumbing, cabling and other embedded fixtures that may be encountered along the impact path. While the ultrasonic/sonic jackhammer of the invention is able to cut concrete and asphalt, it generates little back-propagated shocks or vibrations onto the mounting fixture, and can be operated from an automatic platform or robotic system. PNEUMATICS; ULTRASONICS; IMPACTORS; DRILLING; HAMMERS BRITTLE MATERIALS; DRILL BITS; PROTOTYPES; VIBRATION

Bar-Cohen, Yoseph (Inventor); Sherrit, Stewart (Inventor); Herz, Jack L. (Inventor)

2014-01-01

431

Ultrasonic Leak Detection System  

NASA Technical Reports Server (NTRS)

A system for detecting ultrasonic vibrations. such as those generated by a small leak in a pressurized container. vessel. pipe. or the like. comprises an ultrasonic transducer assembly and a processing circuit for converting transducer signals into an audio frequency range signal. The audio frequency range signal can be used to drive a pair of headphones worn by an operator. A diode rectifier based mixing circuit provides a simple, inexpensive way to mix the transducer signal with a square wave signal generated by an oscillator, and thereby generate the audio frequency signal. The sensitivity of the system is greatly increased through proper selection and matching of the system components. and the use of noise rejection filters and elements. In addition, a parabolic collecting horn is preferably employed which is mounted on the transducer assembly housing. The collecting horn increases sensitivity of the system by amplifying the received signals. and provides directionality which facilitates easier location of an ultrasonic vibration source.

Youngquist, Robert C. (Inventor); Moerk, J. Steven (Inventor)

1998-01-01

432

The use of high-intensity ultrasonics  

Microsoft Academic Search

Features of the application of high-intensity ultrasonics are related to intensity measurements of ultrasonic oscillation and high-intensity ultrasonic effects on the resonance system. High-intensity ultrasonics applications in various technologies are considered, taking into account filtration and catalysis, drying, aerosol and hydrosol coagulation, emulsification and dispersion, metal-powder production, ultrasonic liquid degassing, cavitation, ultrasonic cleaning, metallizing and soldering, welding in an ultrasonic

A. Puskar

1982-01-01

433

Precision Thickness Variation Mapping via One-Transducer Ultrasonic High Resolution Profilometry for Sample with Irregular or Rough Surface  

NASA Technical Reports Server (NTRS)

An apparatus and method for determination of sample thickness and surface depression utilizing ultrasonic pulses. The sample is held in a predetermined position by a support member having a reference surface. Ultrasonic pulses travel through a medium of known velocity propagation and reflect off the reference surface and a sample surface. Time of flight data of surface echoes are converted to distances between sample surfaces to obtain computer-generated thickness profiles and surface mappings.

Roth, Don J. (Inventor)

1997-01-01

434

Precision Thickness Variation Mapping Via One-Transducer Ultrasonic High Resolution Profilometry for Sample With Irregular or Rough Surface  

NASA Technical Reports Server (NTRS)

An apparatus and method for determination of sample thickness and surface depression utilizing ultrasonic pulses is discussed. The sample is held in a predetermined position by a support member having a reference surface. Ultrasonic pulses travel through a medium of known velocity propagation and reflect off the reference surface and a sample surface. Time of flight data of surface echoes are converted to distances between sample surfaces to obtain computer-generated thickness profiles and surface mappings.

Roth, Don J. (Inventor)

1996-01-01

435

Ultrasonic Processing of Materials  

SciTech Connect

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.

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

2005-06-30

436

Automated ultrasonic measuring system  

NASA Astrophysics Data System (ADS)

An experiment in which a microcomputer in the single-chip mode is utilized to control an acoustic-imaging process is described. The experiment was conducted using an aluminum specimen with a spherical deformation on the upper surface, a noncontact-piezoelectric transducers to transmit waves, and an eight-bit microprocessor. The effects of deformation on the transmitted acoustic waves and on the reflected ultrasonic waves are investigated. Intensity distributions for the specimen are studied. Block diagrams of the automated ultrasonic-measuring system are provided.

Umeagukwu, C. I.; Peters, W. H.; Dickerson, J. R.; Ranson, W. F.

1987-01-01

437

Ultrasonic/Sonic Jackhammer  

NASA Technical Reports Server (NTRS)

An ultrasonic/sonic jackhammer (USJ) is the latest in a series of related devices. Each of these devices cuts into a brittle material by means of hammering and chiseling actions of a tool bit excited with a combination of ultrasonic and sonic vibrations. A small-scale prototype of the USJ has been demonstrated. A fully developed, full-scale version of the USJ would be used for cutting through concrete, rocks, hard asphalt, and other materials to which conventional pneumatic jackhammers are applied, but the USJ would offer several advantages over conventional pneumatic jackhammers.

Bar-Cohen, Yoseph; Sherrit, Stewart; Herz, Jack

2005-01-01

438

Ultrasonic characterization of solid liquid suspensions  

DOEpatents

Using an ultrasonic field, properties of a solid liquid suspension such as through-transmission attenuation, backscattering, and diffuse field are measured. These properties are converted to quantities indicating the strength of different loss mechanisms (such as absorption, single scattering and multiple scattering) among particles in the suspension. Such separation of the loss mechanisms can allow for direct comparison of the attenuating effects of the mechanisms. These comparisons can also indicate a model most likely to accurately characterize the suspension and can aid in determination of properties such as particle size, concentration, and density of the suspension.

Panetta, Paul D.

2010-06-22

439

Studies on ultrasonic microfeeding of fine powders  

NASA Astrophysics Data System (ADS)

Microfeeding can be used, inter alia, for solid freeforming, colour management and pharmaceutical dosing. In this work, a computer-controlled microfeeding system using ultrasonic vibration of a capillary was built. This paper describes the powder structures in the microfeeding process and defines the main processing factors affecting the mean dose mass. The experimental results show that the particle structures in the capillary tube can be divided into three types: arching, plugging and blocking. The nozzle diameter, transmission fluid depth, waveforms, voltage amplitude, frequency and oscillation duration all influence the dose mass. Among these factors, the nozzle diameter, voltage amplitude and oscillation duration can be used to control the dose mass.

Lu, Xuesong; Yang, Shoufeng; Evans, Julian R. G.

2006-06-01

440

Coupling apparatus for ultrasonic medical diagnostic system  

NASA Technical Reports Server (NTRS)

An apparatus for the ultrasonic scanning of a breast or other tissue is reported that contains a cavity for receiving the breast, a vacuum for drawing the breast into intimate contact with the walls of the cavity, and transducers coupled through a fluid to the cavity to transmit sound waves through the breast. Each transducer lies at the end of a tapered chamber which has flexible walls and which is filled with fluid, so that the transducer can be moved in a raster pattern while the chamber walls flex accordingly, with sound transmission always occurring through the fluid.

Frazer, R. E. (inventor)

1978-01-01

441

Ultrasonic Study of Dislocation Dynamics in Lithium -  

NASA Astrophysics Data System (ADS)

Experimental studies of dislocation dynamics in LiF single crystals, using ultrasonic techniques combined with dynamic loading, were performed to investigate the time evolution of the plastic deformation process under a short stress pulse at room temperature, and the temperature dependence of the dislocation damping mechanism in the temperature range 25 - 300(DEGREES)K. From the former, the time dependence of the ultrasonic attenuation was understood as resulting from dislocation multiplication followed by the evolution of mobile dislocations to immobile ones under large stress. From the latter, the temperature dependence of the ultrasonic attenuation was interpreted as due to the motion of the dislocation loops overcoming the periodic Peierls potential barrier in a manner analogous to the motion of a thermalized sine-Gordon chain under a small stress. The Peierls stress obtained from the experimental results by application of Seeger's relaxation model with exponential dislocation length distribution was 4.26MPa, which is consistent with the lowest stress for the linear relation between the dislocation velocity and stress observed by Flinn and Tinder.

Han, Myeong-Deok

1987-09-01

442

The use of high-intensity ultrasonics  

NASA Astrophysics Data System (ADS)

Features of the application of high-intensity ultrasonics are related to intensity measurements of ultrasonic oscillation and high-intensity ultrasonic effects on the resonance system. High-intensity ultrasonics applications in various technologies are considered, taking into account filtration and catalysis, drying, aerosol and hydrosol coagulation, emulsification and dispersion, metal-powder production, ultrasonic liquid degassing, cavitation, ultrasonic cleaning, metallizing and soldering, welding in an ultrasonic field, and ultrasonics in material machining. Other topics considered are related to ultrasonics in the crystallization of metals and alloys, ultrasonics in heat and chemical-heat treatment, safety and hygiene of working with ultrasonic devices, the effect of high-intensity ultrasonics on solids, the properties of materials after prior action of high-intensity ultrasound, the fatigue of materials during high-frequency stressing, and ultrasonic oscillation and material deformation characteristics. The technological exploitation of ultrasound during material forming is also discussed.

Puskar, A.

443

Ultrashort Pulse Propagation in the Linear Regime  

E-print Network

First, we investigate the Bouguer-Lambert-Beer (BLB) law as applied to the transmission of ultrashort pulses through water in the linear absorption regime. We present a linear theory for propagation of ultrashort laser pulses, and related...

Wang, Jieyu

2010-07-14

444

Noncontact determination of elastic moduli by two-dimensional Fourier transformation and laser ultrasonic technique  

NASA Astrophysics Data System (ADS)

A laboratory instrument that utilizes broadband laser ultrasonics and two-dimensional Fourier transformation for signal processing has been developed to characterize the properties of various foils and plates. Laser ultrasonics generation is achieved by using a pulsed laser which deposits pulsed laser energy on the surface of the specimen. The displacement of the resulting broadband ultrasonic modes is monitored using a two-wave mixing photorefractive interferometer. By means of the two-dimensional Fourier transformation of the detected spatial and temporal displacement wave forms, the image of density of state (DOS) for the excited ultrasound is obtained, and from it the materials properties are extracted. Results are presented for a 150?m thick paper sample, a 50?m stainless steel foil, and a 1.27mm thick aluminum plate. The DOS image demonstrates the ability to measure the properties of each generated ultrasonic modes and provides a direct, nondestructive, measure of elastic moduli of the tested specimens.

Zhang, Xinya; Jackson, Ted; Lafond, Emmanuel

2005-02-01

445

Simulation of transducer-couplant effects on broadband ultrasonic signals  

NASA Technical Reports Server (NTRS)

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.

Vary, A.

1980-01-01

446

Acousto-ultrasonic characterization of fiber reinforced composites  

NASA Technical Reports Server (NTRS)

The advantageous aspects of acoustic emission and ultrasonic methodologies are combined in a technique which operates by introducing a repeating series of ultrasonic pulses into a material. The waves introduced simulate the spontaneous stress waves that would arise if the material were put under stress as in the case of acoustic emission measurements. These benign stress waves are detected by an acoustic emission sensor. The physical arrangement of the ultrasonic (input) transducer and acoustic emission (output) sensor is such that the resultant waveform carries an imprint of morphological factors that govern or contribute to material performance. The output waveform is quite complex, but it can be quantitized in terms of a "stress wave factor". The stress wave factor, which can be defined in a number of ways, is essentially a relative measure of the efficiency of energy dissipation in a material. If flaws or other material anomalies exist in the volume being examined, their combined effect will appear in the stress wave factor.

Vary, A.

1982-01-01

447

Broadband high-frequency measurement of ultrasonic attenuation of tissues and liquids.  

PubMed

The ongoing expansion of the frequency range used for ultrasonic imaging requires increasing attention to the acoustic attenuation of biomaterials. This work presents a novel method for measuring the attenuation of tissue and liquids in vitro on the basis of single transmission measurements. Ultrasound was generated by short laser pulses directed onto a silicon wafer. In addition, unfocused piezoelectric transducers with a center frequency of 50 MHz were used to detect and emit ultrasound. The laser ultrasound method produces signals with a peak frequency of 30 MHz. In comparison to piezoelectric generation, pulse laser excitation provides approximately 4 times higher amplitudes and 20% larger bandwidth. By using two excitation methods in succession, the attenuation parameters of porcine fat samples with thicknesses in the range of 1.5 to 20 mm could be determined quantitatively within a total frequency range of 5 to 45 MHz. The setup for liquid measurements was tested on samples of human blood and olive oil. Our results are in good agreement with reports in literature. PMID:23221212

Bauer-Marschallinger, Johannes; Berer, Thomas; Grun, Hubert; Roitner, Heinz; Reitinger, Bernhard; Burgholzer, Peter

2012-12-01

448

Broadband Ultrasonic Transducers  

NASA Technical Reports Server (NTRS)

New geometry spreads out resonance region of piezoelectric crystal. In new transducer, crystal surfaces made nonparallel. One surface planar; other, concave. Geometry designed to produce nearly uniform response over a predetermined band of frequencies and to attenuate strongly frequencies outside band. Greater bandwidth improves accuracy of sonar and ultrasonic imaging equipment.

Heyser, R. C.

1986-01-01

449

Ultrasonic Processing of Materials  

Microsoft Academic Search

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

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

2005-01-01

450

Experiments with Ultrasonic Transducers.  

ERIC Educational Resources Information Center

Discusses the use of 40 kHz ultrasonic transducers to study wave phenomena. Determines that the resulting wavelength of 9 mm allows acoustic experiments to be performed on a tabletop. Includes transducer characteristics and activities on speed of sound, reflection, double- and single-slit diffraction, standing waves, acoustical zone plate, and…

Greenslade, Thomas R., Jr.

1994-01-01

451

Ultrasonic Drilling and Coring  

NASA Technical Reports Server (NTRS)

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.

Bar-Cohen, Yoseph

1998-01-01

452

Scanning ultrasonic probe  

DOEpatents

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 analyzed at one time and their positions accurately located in a single pass down the test specimen.

Kupperman, David S. (Oak Park, IL); Reimann, Karl J. (Lisle, IL)

1982-01-01

453

Scanning ultrasonic probe  

DOEpatents

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.

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

1980-12-09

454

Ultrasonic cleaning: Fundamental theory and application  

NASA Technical Reports Server (NTRS)

This presentation describes: the theory of ultrasonics, cavitation and implosion; the importance and application of ultrasonics in precision cleaning; explanations of ultrasonic cleaning equipment options and their application; process parameters for ultrasonic cleaning; and proper operation of ultrasonic cleaning equipment to achieve maximum results.

Fuchs, F. John

1995-01-01

455

Ultrasonic wave velocity measurement in small polymeric and cortical bone specimens  

NASA Technical Reports Server (NTRS)

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.

Kohles, S. S.; Bowers, J. R.; Vailas, A. C.; Vanderby, R. Jr

1997-01-01

456

Localized transmission of electromagnetic energy  

Microsoft Academic Search

Novel electromagnetic directed-energy pulse train (EDEPT) solutions of Maxwell's equations have been obtained. One particular solution, the modified-power-spectrum (MPS) pulse, will be described in detail. EDEPT's such as the MPS pulses, can be tailored to give localized energy transmission along a specified direction in space that is significantly improved over conventional diffraction-limited beams. Moreover, they represent fields that recover their

Richard W. Ziolkowski

1989-01-01

457

Optical and ultrasonic monitoring of femtosecond laser filamentation in fused silica  

Microsoft Academic Search

Millimeter-long filaments and accompanying luminous plasma and defect channels created in fused silica (FS) by single focused femtosecond laser pulses with supercritical powers were probed in situ using optical imaging and contact ultrasonic techniques. Above the threshold pulse energy Eopt=5?J corresponding to a few megawatt power levels pulses collapse due to self-focusing, producing channels filled by electron–hole plasma and luminescent

Vygantas Mizeikis; Saulius Juodkazis; Tadas Balciunas; Sergey I. Kudryashov; Vladimir D. Zvorykin; Andrei A. Ionin; Hiroaki Misawa

2009-01-01

458

Pulse shaping system  

DOEpatents

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

Skeldon, Mark D. (Penfield, NY); Letzring, Samuel A. (Jemez Springs, NM)

1999-03-23

459

Pulse shaping system  

DOEpatents

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

Skeldon, M.D.; Letzring, S.A.

1999-03-23

460

PSIDD: A Post-Scan Interactive Data Display system for ultrasonic scans  

NASA Technical Reports Server (NTRS)

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.

Roth, Don J.; Szatmary, Steven A.

1993-01-01

461

Ultrasonic texture characterization of aluminum, zirconium and titanium alloys  

SciTech Connect

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.

Anderson, A.J.

1997-10-08

462

Acousto-ultrasonic characterization of fiber reinforced composites  

NASA Technical Reports Server (NTRS)

The acousto-ultrasonic technique combines advantageous aspects of acoustic emission and ultrasonic methodologies. Acousto-ultrasonics operates by introducing a repeating series of ultrasonic pulses into a material. The waves introduced simulate the spontaneous stress waves that would arise if the material were put under stress as in the case of acoustic emission measurements. These benign stress waves are detected by an acoustic emission sensor. The physical arrangement of the ultrasonic (input) transducer and acoustic emission (output) sensor is such that the resultant waveform carries an imprint of morphological factors that govern or contribute to material performance. The output waveform is quite complex, but it can be quantitized in terms of a 'stress wave factor'. The stress wave factor, which can be defined in a number of ways, is essentially a relative measure of the efficiency of energy dissipation in a material. If flaws or other material anomalies exist in the volume being examined, their combined effect will appear in the stress wave factor.

Vary, A.

1981-01-01

463

Micromachined piezoelectric ultrasonic transducer with ultra-wide frequency bandwidth  

NASA Astrophysics Data System (ADS)

An ultrasonic transducer with a wide frequency bandwidth is always preferred for diagnostic ultrasound imaging, because a wide frequency bandwidth can reduce the duration of an ultrasonic pulse and enhance the axial imaging resolution. However, the frequency bandwidth of both conventional ultrasonic transducer and normal piezoelectric micromachined ultrasonic transducer (pMUT) is quite limited. To overcome this limitation, the mode-merging pMUT is presented in this letter. By using the rectangular membrane with large length/width aspect ratio, several resonant modes are excited within a narrow frequency range. When this pMUT works in a largely damped medium, excited modes are merged together and result in an ultra-wide bandwidth. A -6 dB bandwidth of 95% is measured in water for the proposed pMUT without matching layer, which is much broader than that of conventional pMUTs. Benefited from such ultra-wide frequency bandwidth, the pulse duration of 1 ?s is achieved at a central frequency of 1.24 MHz. If this ultra-wide bandwidth pMUT is utilized to replace the conventional transducer for diagnostic ultrasound imaging, the axial resolution can be significantly enhanced without compromising imaging depth.

Wang, Tao; Kobayashi, Takeshi; Lee, Chengkuo

2015-01-01

464

COMPRESSION, ESTIMATION, AND ANALYSIS OF ULTRASONIC SIGNALS  

E-print Network

COMPRESSION, ESTIMATION, AND ANALYSIS OF ULTRASONIC SIGNALS BY GUILHERME CARDOSO DE CARDOSO .................................................................. 5 2.2 Ultrasonic Imaging ................................................................ 7 2. THRESHOLDING TECHNIQUES FOR DENOISING AND COMPRESSING ULTR