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1

Through Transmission Technique for Ultrasonic Attenuation Measurement Using Broadband, Plane Wave Pulses  

Microsoft Academic Search

One problem with present pulse-echo or through transmission, phase sensitive methods for measuring ultrasonic attenuation coefficients is that d iffraction corrections are necessary because of the finite size o f the source. Another difficulty common to spectral subtraction methods lies in generating an acoustic pulse with sufficient energy over the frequency range of interest. These problems can be ameliorated by

Gerald K. Harris; Bruce A. Herman; Stephen W. Smith; William J. Bodine

1983-01-01

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

Experiments in Pulsed Ultrasonics  

ERIC Educational Resources Information Center

Describes and apparatus designed to generate and detect pulsed ultrasonics in solids and liquids over the frequency range 1-20 MHz. Experiments are suggested for velocity of sound, elastic constant and ultrasonic attenuation measurements on various materials over a wide temperature range. The equipment should be useful for demonstration purposes.…

Palmer, S. B.; Forster, G. A.

1970-01-01

4

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

5

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

6

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Ultrasonic pulsed doppler imaging system. 892.1550 Section...Devices § 892.1550 Ultrasonic pulsed doppler imaging system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that...

2010-04-01

7

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Ultrasonic pulsed doppler imaging system. 892.1550 Section...Devices § 892.1550 Ultrasonic pulsed doppler imaging system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that...

2009-04-01

8

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

9

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

10

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

11

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

12

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

13

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

14

Wireless power transmission using ultrasonic guided waves  

NASA Astrophysics Data System (ADS)

The unavailability of suitable power supply at desired locations is currently an important obstacle in the development of distributed, wireless sensor networks for applications such as structural health monitoring of aircraft. Proposed solutions range from improved batteries to energy harvesting from vibration, temperature gradients and other sources. A novel approach is being investigated at Cardiff University School of Engineering in cooperation with Airbus. It aims to utilise ultrasonic guided Lamb waves to transmit energy through the aircraft skin. A vibration generator is to be placed in a location where electricity supply is readily available. Ultrasonic waves generated by this device will travel through the aircraft structure to a receiver in a remote wireless sensor node. The receiver will convert the mechanical vibration of the ultrasonic waves back to electricity, which will be used to power the sensor node. This paper describes the measurement and modelling of the interference pattern which emerges when Lamb waves are transmitted continuously as in this power transmission application. The discovered features of the pattern, such as a large signal amplitude variation and a relatively high frequency, are presented and their importance for the development of a power transmission system is discussed.

Kural, A.; Pullin, R.; Featherston, C.; Paget, C.; Holford, K.

2011-07-01

15

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

16

Ultrasonic Flowmetering with Reflected Pulses.  

National Technical Information Service (NTIS)

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. The present paper describes the successful continuation - to the...

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

1984-01-01

17

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

18

The pulse transmission mode laser  

SciTech Connect

The Pulse Transmission Mode (PTM) laser has been examined as a possible laser for the WRELADS (Weapons Research Establishment Laser Depth Sounder) system under development at the Electronic Research Laboratories of DRCS. In particular the PTM laser offers a means of generating the short pulses (5 ns FWHM) required by the system but its output is limited by gain saturation to < 40 millijoule.

See, B.A.

1980-09-01

19

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

20

[Research on ultrasonic permeability of low intensity pulsed ultrasound through PTFE membrane and Bio-Gide collagen membrane].  

PubMed

The aim of the present study was to detect the transmission rate of ultrasonic low intensity pulsed ultrasound (LIPUS) through polytetrafluoroethylene (PTFE) membrane (Thickness: 0.01 mm) and Bio-Gide collagen membrane, and to provide the basis for the barrier membrane selection on the study of LIPUS combined with guided tissue regeneration (GTR). The ultrasonic (LIPUS, frequency 1.5 MHz, pulse width 200 micros, repetition rate 1.0 kHz) transmission coefficient of the two kinds of barrier membrane were detected respectively through setting ten groups from 10 to 100mW/cm2 every other 10 mW/cm2. We found in the study that the ultrasonic transmission coefficient through 0.01 mm PTFE membrane was 78.1% to 92.%, and the ultrasonic transmission coefficient through Bio-Gide collagen membrane was 43.9% to 55.8%. The ultrasonic transmission coefficient through PTFE membrane was obviously higher than that through Bio-Gide collagen membrane. The transmission coefficient of the same barrier membrane of the ultrasonic ion was statistically different under different powers (P < 0.05). The results showed that the ultrasonic transmittance rates through both the 0.01 mm PTFE membrane and Bio-Gide collagen membrane were relatively high. We should select barrier membranes based on different experimental needs, and exercise ultrasonic transmission coefficient experiments to ensure effective power. PMID:24645590

Chai, Zhaowu; Zhao, Chunliang; Song, Jinlin; Deng, Feng; Yang, Ji; Gao, Xiang; Liu, Minyi

2013-12-01

21

Ultrasonic spectrum analysis using frequency-tracked gated RF pulses  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

22

Inline ultrasonic rheometry by pulsed Doppler.  

PubMed

This will be a discussion of the non-invasive determination of the viscosity of a non-Newtonian fluid in laminar pipe flow over the range of shear rates present in the pipe. The procedure used requires knowledge of the flow profile in and the pressure drop along a long straight run of pipe. The profile is determined by using a pulsed ultrasonic Doppler velocimeter. This approach is ideal for making non-invasive, real-time measurements for monitoring and control. Rheograms of a shear thinning gel will be presented. The operating parameters and limitations of the Doppler-based instrument will be discussed. The most significant limitation is velocity gradient broadening of the Doppler spectra near the walls of the pipe. This limitation can be significant for strongly shear thinning fluids (depending also on the ratio of beam to pipe diameter and the transducer's insertion angle). PMID:16808950

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

2006-12-22

23

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

24

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

Code of Federal Regulations, 2011 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1560 Ultrasonic pulsed echo imaging system. (a) Identification....

2011-04-01

25

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

Code of Federal Regulations, 2010 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1560 Ultrasonic pulsed echo imaging system. (a) Identification....

2010-04-01

26

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Code of Federal Regulations, 2011 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1550 Ultrasonic pulsed doppler imaging system. (a)...

2011-04-01

27

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Code of Federal Regulations, 2012 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1550 Ultrasonic pulsed doppler imaging system. (a)...

2012-04-01

28

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1560 Ultrasonic pulsed echo imaging system. (a) Identification....

2014-04-01

29

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

Code of Federal Regulations, 2012 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1560 Ultrasonic pulsed echo imaging system. (a) Identification....

2012-04-01

30

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1550 Ultrasonic pulsed doppler imaging system. (a)...

2014-04-01

31

Ultrasonic Synthetic Aperture Focusing Using Unfocused Pulse-Echo Transducers.  

National Technical Information Service (NTIS)

The lateral resolution of digital data from the unfocused pulse-echo transducers used in conventional ultrasonic inspections can be improved using the synthetic aperture focusing technique (SAFT). For practical applications it is important to minimise the...

S. F. Burch J. T. Burton

1984-01-01

32

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1550 Ultrasonic pulsed doppler imaging system. (a)...

2013-04-01

33

A Novel Method of Distance Measurement Based on Pulse Position Modulation and Synchronization of Chaotic Signals Using Ultrasonic Radar Systems  

Microsoft Academic Search

This paper deals with a novel method of transmission and receipt of a signal based on both the property of two chaotic systems generating the same chaotic signal when they are synchronized and the property of pulse position modulation (PPM) to be insensitive to the distortions of the transmission channel. The method is discussed in the context of ultrasonic radar

Francesco Alonge; Marco Branciforte; Francesco Motta

2009-01-01

34

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

35

Power and Interactive Information Transmission to Implanted Medical Device Using Ultrasonic  

Microsoft Academic Search

In this paper, we propose the power supply and the bi-directional information transmission system using ultrasonic. Ultrasonic does not interfere with the electronic circuits of implanted devices and is safe for a living body. Previously, we have clarified experimentally that ultrasonic is applicable to power and information transmission. This study deals with improving information transmission speed from the inside to

Shin-nosuke Suzuki; Shunsuke Kimura; Tamotsu Katane; Hideo Saotome; Osami Saito; Kazuhito Kobayashi

2002-01-01

36

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

37

Resonant ultrasonic wireless power transmission for bio-implants  

NASA Astrophysics Data System (ADS)

In this paper, we present the ultrasonic wireless power transmission system as part of a brain-machine interface (BMI) system in development to supply the required electric power. Making a small-size implantable BMI, it is essential to design a low power unit with a rechargeable battery. The ultrasonic power transmission system has two piezoelectric transducers, facing each other between skin tissues converting electrical energy to mechanical vibrational energy or vice versa. Ultrasound is free from the electromagnetic coupling effect and medical frequency band limitations which making it a promising candidate for implantable purposes. In this paper, we present the design of piezoelectric composite transducer, the rectifier circuit, and rechargeable battery that all packaged in biocompatible titanium can. An initial prototype device was built for demonstration purpose. The early experimental results demonstrate the prototype device can reach 50% of energy transmission efficiency in a water medium at 20mm distance and 18% in animal skin tissue at 18mm distance, respectively.

Lee, Sung Q.; Youm, Woosub; Hwang, Gunn; Moon, Kee S.; Ozturk, Yusuf

2014-03-01

38

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

39

Pulse transmission mode laser. Technical memo  

SciTech Connect

The Pulse Transmission Mode (PTM) laser has been examined as a possible laser for the WRELADS system under development at the Electronic Research Laboratories of DRCS. In particular the PTM laser offers a means of generating the short pulses (5 ns FWHM) required by the system but its output is limited by gain saturation to < 40 millijoule.

See, B.A.

1980-09-01

40

Wideband optical measurements of ultrasonic pulses  

NASA Technical Reports Server (NTRS)

Calibrated masurements of acoustic surface wave pulses by wide bandwidth differential interferometry are described. By interrogating the interference pattern formed by superimposing two optical beams reflected from the surface at slightly separated points, an output signal proportional to instantaneous surface particle displacement is obtained. Response to ideal propagating step function displacements is analyzed and measurements of gated pulses are described.

Claus, R. O.; Cantrell, J. H., Jr.

1981-01-01

41

Input Pulse Response in Nonlinear Transmission Line  

NASA Astrophysics Data System (ADS)

Nonlinear transmission lines have been demonstrated to be an effective technique for generating high power ultrawideband or mesoband radiation without the need for a vacuum system, electron beam, or magnet. Experiments have been performed at UM on a discrete element nonlinear transmission line that uses ferrite inductors as the nonlinear element. Pulse sharpening of multi-kA input pulses has been observed in addition to the generation of oscillations at the characteristic LC frequency. The response to various input pulses to excite a single inductor on a single stage of the nonlinear transmission line, which may consist of a linear capacitor and a nonlinear inductor, will be modeled. Also studied is the pulse response to a nonlinear telegraphic equation. Results of these modeling efforts as well as experimental results performed at UM will be presented.

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

2010-11-01

42

Evaluation of a pulsed ultrasonic Doppler flowmeter  

NASA Technical Reports Server (NTRS)

The in vivo application of the pulsed ultrasound Doppler velocity meter (PUDVM) for measuring arterial velocity waveforms is reported. In particular, the performance of the PUDVM is compared with a hot film anemometer of proven accuracy.

Wells, M. K.

1973-01-01

43

Axisymmetric free surface waves and droplets caused by ultrasonic pulses  

NASA Astrophysics Data System (ADS)

The numerical simulation of the deformation of a liquid free surface owing to ultrasonic beams is considered. Specifically, when an ultrasonic pulse of sufficient intensity is focused near the surface of water, the resulting acoustic pressure deforms the surface and may force a droplet to be ejected. It has been shown that a simple boundary integral equation method for inviscid incompressible fluid can, with reasonable accuracy, model the deformation of the water surface when the initial velocity potential on the surface is given. Here the method is used to compute the surface deformation when a series of pulses are applied. The velocity field near the surface is also considered. This research is part of a study of the lung damage caused by ultrasonic imaging. It has been observed in animal experiments that a focused ultrasonic beam can cause lung lesions. Since the animal flesh is mostly water and the lung is filled with air, a simple model of the interaction features an incompressible fluid with a free surface with small surface tension. Two regimes are observed: one a stationary solitary wave, the second a droplet emission.

Tjan, Kuan-Khoon; Phillips, William R. C.

2004-11-01

44

Axisymmetric free surface waves and droplets caused by ultrasonic pulses  

NASA Astrophysics Data System (ADS)

The numerical simulation of the deformation of a liquid free surface owing to ultrasonic beams is considered. Specifically, when an ultrasonic pulse of sufficient intensity is focused near the surface of water, the resulting acoustic pressure deforms the surface and may force a droplet to be ejected. It has been shown that a simple boundary integral equation method for inviscid incompressible fluid can, with reasonable accuracy, model the deformation of the water surface when the initial velocity potential on the surface is given. Here the method is used to compute the surface deformation when a series of pulses are applied. In this case, the reflected waves from the deformed surface must, as the time progresses, be taken into account. The velocity field near the surface is also considered. This research is part of a study of the lung damage caused by ultrasonic imaging. It has been observed in animal experiments that a focused ultrasonic beam can cause lung lesions. Since the animal flesh is mostly water and the lung is filled with air, a simple model of the interaction features an incompressible fluid with a free surface with small surface tension. Two regimes are observed: one a stationary solitary wave, the second a droplet emission.

Chung, Hyuck; Phillips, William Rc

2003-11-01

45

Generalized pulse equations for through-transmission evaluation of arbitrary multilayered structures  

NASA Technical Reports Server (NTRS)

Generalized transit-time and pulse-amplitude equations have been derived for modeling the ultrasonic through-transmission wave propagation of an arbitrary n-layered structure. The equations can be programmed into an expert system and used to identify and predict the through-transmission pulse signals from the critical interfaces of a multilayered structure. To test the formulas, the through-transmission responses from one- and three-layered configurations were measured in the laboratory and compared with computer-generated data that were determined using the derived equations. The results verify the validity of the formulas.

Chern, E. James; Nielsen, Hatsumi T. C.

1990-01-01

46

Ultrasonic flowmetering with reflected pulses. Final report  

Microsoft Academic Search

Consolidated Edison of New York City has expressed the need for a new gas meter for accurately monitoring large-diameter interdistrict gas-transmission lines for loss due to theft or leakage. This paper describes the successful continuation - to the point of making recommendations for field testing - of a previous research effort aimed at developing a new flowmeter for Con Edison.

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

1984-01-01

47

Measurement of ice accretion using ultrasonic pulse echo techniques  

NASA Technical Reports Server (NTRS)

Many figures are given to illustrate the measurement of ice deposition using ultrasonic pulse echo techniques. The basic concept is to measure the thickness of the ice by relating the pulse echo time to the speed of sound. The measurements are made in an icing research tunnel (IRT), where echo patterns are videotaped during icing exposures under a variety of conditions. Typical echo patterns for different types of ice are illustrated. A table summarizing the icing rates measured in the IRT, along with the presence or absence of surface water is also given.

Hansman, R. John, Jr.; Kirby, Mark S.

1987-01-01

48

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.

Liu, Jie; Insana, Michael F.

2009-01-01

49

Improved pulsed broadband ultrasonic spectroscopy for analysis of liquid-particle flow  

Microsoft Academic Search

The paper contains an investigation of broadband pulsed ultrasonic spectroscopy techniques, intended for testing of suspensions, such as a liquid-particle flow containing small diameter particles. Influence of traditional and novel broadband pulse shapes on quality of frequency spectra is analysed, as well as pulse design aspects leading to an optimal shape of an ultrasonic excitation wave. Effects that may influence

Barbara M. Wrobel

2011-01-01

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

Simulation of ultrasonic pulse propagation through the abdominal wall.  

PubMed

Ultrasonic pulse propagation through the abdominal wall has been simulated using a model for two-dimensional propagation through anatomically realistic tissue cross sections. The time-domain equations for wave propagation in a medium of variable sound speed and density were discretized to obtain a set of coupled finite-difference equations. These difference equations were solved numerically using a two-step MacCormack scheme that is fourth-order accurate in space and second-order accurate in time. The inhomogeneous tissue of the abdominal wall was represented by two-dimensional matrices of sound speed and density values. These values were determined by processing scanned images of abdominal wall cross sections stained to identify connective tissue, muscle, and fat, each of which was assumed to have a constant sound speed and density. The computational configuration was chosen to simulate that of wavefront distortion measurements performed on the same specimens. Qualitative agreement was found between those measurements and the results of the present computations, indicating that the computational model correctly depicts the salient characteristics of ultrasonic wavefront distortion in vivo. However, quantitative agreement was limited by the two-dimensionality of the computation and the absence of detailed tissue microstructure. Calculations performed using an asymptotic straight-ray approximation showed good agreement with time-shift aberrations predicted by the full-wave method, but did not explain the amplitude fluctuations and waveform distortion found in the experiments and the full-wave calculations. Visualization of computed wave propagation within tissue cross sections suggests that amplitude fluctuations and waveform distortion observed in ultrasonic propagation through the abdominal wall are associated with scattering from internal inhomogeneities such as septa within the subcutaneous fat. These observations, as well as statistical analysis of computed and observed amplitude fluctuations, suggest that weak fluctuation models do not fully describe ultrasonic wavefront distortion caused by the abdominal wall. PMID:9265762

Mast, T D; Hinkelman, L M; Orr, M J; Sparrow, V W; Waag, R C

1997-08-01

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

Design Considerations for Transmission Lines and Pulse-Forming Networks.  

National Technical Information Service (NTIS)

The lumped-constant analysis of transmission lines is given. Transient voltages and currents in infinite, open circuit, and terminated transmission lines are considered. The use of a transmission line as a pulse generator is discussed. The optimum operati...

R. W. Hawkins

1964-01-01

54

Transport parameters for pulsed ultrasonic waves propagating in an aluminum foam  

NASA Astrophysics Data System (ADS)

Aluminum foams have now been studied for many years in large part because of their applications as light-weight elastic materials (e.g., car bumpers, aerospace engineering applications). The pore size and the spatial distribution of the pores govern the mechanical behavior of the foam and can vary enormously depending on the method of manufacturing. Thus, new methods for the nondestructive characterization of these materials are needed. We present here a set of experimental ultrasonic methods in a range of frequencies where the ultrasonic waves are multiply scattered in the medium. In this regime, the propagation is described by ultrasonic transport parameters which are related to the microstructure of the foam. The diffusion coefficient and the absorption mean free path have been determined in pulse transmission experiments by fitting the solution of the diffusion equation to the average intensity, the so-called time of flight distribution. To more fully characterize the medium, the transport mean path and the diffusion coefficient have been measured in backscattering experiments using the static and dynamic coherent backscattering effects. For both methods, the properties of the sample interfaces have been taken into account.

Tourin, Arnaud; Derode, Arnaud; Mamou, Victor; Fink, Mathias; Page, John; Cowan, Michael L.

2002-11-01

55

Nonlinear transmission lines for pulse shaping in silicon  

Microsoft Academic Search

Abstract Non-linear transmission lines (NLTL) are used for pulse shaping. We developed the theory of pulse ,propagation through the NLTL. The problem of a wide pulse degenerating into multiple pulses rather than a single pulse is solved by using a novel gradually scaled NLTL. We exploit certain favorable properties of accumulation ,mode ,MOS varactors to design an NLTL that can

E. Afshari; A. Hajimiri

2005-01-01

56

Non-linear transmission lines for pulse shaping in silicon  

Microsoft Academic Search

Non-linear transmission lines (NLTL) are used for pulse shaping. We developed the theory of pulse propagation through the NLTL. The problem of a wide pulse degenerating into multiple pulses rather than a single pulse is solved by using a novel gradually scaled NLTL. We exploit certain favorable properties of accumulation mode MOS varactors to design an NLTL that can sharpen

Ehsan Afshari; A. Hajimiri

2003-01-01

57

Ultrasonic underwater transmission of composite turbine blade structural health  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

58

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

PubMed

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

Xing, Guangzhen; Yang, Ping; He, Longbiao

2013-04-01

59

Wireless transmission of ultrasonic waveforms for monitoring drug tablet properties and defects.  

PubMed

The geometric and mechanical properties of pharmaceutical materials are crucial to their structural, functional and therapeutic effectiveness. The implementation of automated and convenient quality monitoring procedures is an attempt to balance control of quality against the level of testing; within acceptable levels of probability and costs. The capability of rapid/extensive inspections with minimal time and manufacturing interruption make non-contact quality monitoring systems a desirable approach to optimize this balance. In the current study, a wireless transceiver proof of concept system developed for the real-time quality monitoring of tablets during compaction is presented and demonstrated. The effectiveness of ultrasonic wave transmission through the punch-tablet interface is the boundary condition that dictates the viability of the acoustic in-die compaction monitoring approach. These measurements in the current experimental set-up can be used in determining various mechanical and geometric properties of a compact, such as the tablet thickness, mass density, elasticity and/or integrity of the tablet core, and bonding quality between layers depending on the given parameters, as it is compacted. In the current study, it is demonstrated that the reflection of an ultrasonic pulse generated by a transducer embedded in an upper punch from the lower punch-tablet interface can be acquired by the same transducer in the upper punch and the analog waveform can be transmitted to a computer by means of wireless communications for further signal processing and property extraction. The evolution of apparent Young's moduli of a powder bed during a full-compaction cycle is derived from the ultrasonic time of flight of an acoustic waveform acquired during compaction in-die. PMID:22982256

Stephens, J D; Lakshmaiah, M V; Kowalczyk, B R; Hancock, B C; Cetinkaya, C

2013-02-14

60

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

61

Temperature dependence of the ultrasonic transmission through electrical resistance heated imperfect metal–metal interfaces  

Microsoft Academic Search

Because of surface roughness, the area of contact between real surfaces is less than the geometrical area. For this reason the known rules of acoustic reflection and transmission have to be modified for real interfaces. Ultrasonic transmission through imperfect interfaces is commonly described in terms of the contact stiffness model which assumes distributed springs between the surfaces in contact [Proc.

Klaus Offterdinger; Eckhard Waschkies

2004-01-01

62

Through-transmission ultrasonics for on-line sensing and control of thermoplastic fusion bonding processes  

Microsoft Academic Search

The focus of this work is to develop Through-Transmission Ultrasonics (TTU) as a process monitoring technique for non-intrusive, on-line control of thermoplastic fusion bonding. A model is developed to predict the TTU amplitude of a fusion bond by joining the theory of ultrasonic wave propagation through multilayered structures with a model for the evolution of intimate contact at the material

Kirk David Tackitt

1999-01-01

63

Ultrasonic Transmission Characteristics of In vitro Human Cancellous Bone  

NASA Astrophysics Data System (ADS)

An ultrasonic wave transmitted through an in vitro human cancellous bone was experimentally investigated. An osteoporotic cancellous bone specimen was obtained from an in vitro femoral head. A narrow ultrasonic beam was scanned on the specimen surface over an area of 30× 30 mm2 and the transmitted ultrasonic wave was obtained at an interval of 1 mm. Local bone densities corresponding to measurement points using the ultrasonic beam were obtained using a microfocus X-ray computed tomography system. Transmitted slow wave signals were detected at all measurements points; however, the measurable area of a fast wave was greatly reduced and limited because of the osteoporotic low-density specimen. The propagation speed of a slow wave was almost independent of bone density. The propagation speed of the fast wave and the amplitudes of the fast and slow waves considerably depended on bone density. The obtained results imply that the scattered values of the propagation speed of the fast wave and the amplitudes of the fast and slow waves reflect the ultrasonic characteristics of the cancellous bone, which depend on both the bone density and the trabecular macro- and micro-structures.

Mano, Isao; Yamamoto, Tadahito; Hagino, Hiroshi; Teshima, Ryota; Takada, Masahiko; Tsujimoto, Toshiyuki; Otani, Takahiko

2007-07-01

64

An Active Pulse Transmission Line Simulating Nerve Axon  

Microsoft Academic Search

To electronically simulate an animal nerve axon, the authors made an active pulse transmission line using tunnel diodes. The equation of propagation for this line is the same as that for a simplified model of nerve membrane treated elsewhere. This line shapes the signal waveform during transmission, that is, there being a specific pulse-like waveform peculiar to this line, smaller

J. Nagumo; S. Arimoto; S. Yoshizawa

1962-01-01

65

Characterization of Nonlinear Transmission Lines for Short Pulse Amplification  

Microsoft Academic Search

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

Koichi Narahara

2010-01-01

66

Global transmission and reflection coefficients of the ultrasonic component in porous media: a new approach.  

PubMed

The purpose of this paper is to propose a new approach to determining the global ultrasonic transmission and reflection coefficients in a random porous medium. Boundary conditions at the interface of the medium were used to determine local transmission and reflection coefficients. A study of the behavior of different waves inside the medium was carried out to derive a new global formulation that takes interior phenomena into consideration. All the results were obtained independently of the geometrical and physical characteristics of the medium so that the method can be applied to any two-phase porous medium. This study is based on normal incidence ultrasonic wave propagation. PMID:23499138

Nassar, G; Medjdoub, A; Saad, N

2013-08-01

67

Real-time through transmission inspection of aircraft composites using air-coupled ultrasonic arrays  

Microsoft Academic Search

The design, development and initial testing of a fully operational, through transmission ultrasonic array system to perform air-coupled, non-destructive testing (NDT) of advanced composite materials within the aerospace industry is presented. The system offers greater test flexibility and significantly improves the achievable scan rate, when compared with existing water jet systems, without loss of resolution or flaw detection integrity. A

S. P. Kelly; G. Hayward

1995-01-01

68

Characterization of Nonlinear Transmission Lines for Short Pulse Amplification  

NASA Astrophysics Data System (ADS)

Pulse propagation on nonlinear transmission lines (NLTLs), which are transmission lines with regularly spaced Schottky varactors, is investigated for the amplification of short pulses. We recently found that the soliton developed in an NLTL experiences an exponential amplitude growth, when it couples with an existing voltage edge. This paper clarifies how the pulse gain depends on the device parameters, including the line inductance, capacitance, and gradient of voltage edge, and describes the design criteria of an NLTL as a pulse amplifier, together with several results of calculations that examine the potential of the NLTL.

Narahara, Koichi

2010-04-01

69

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

70

Pulsed power transmission line transformer based on modern cable technology  

Microsoft Academic Search

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

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

2003-01-01

71

Rotational swashplate pulse continuously variable transmission based on helical gear axial meshing transmission  

NASA Astrophysics Data System (ADS)

The current research on pulse continuously variable transmission(CVT) is mainly focused on reducing the pulse degree and making pulse degrees a constant value. Current research mainly confined to find out new design parameters by using the method of optimization, and reduce the pulse degree of pulse CVT and its range of variation. But the fact is that the reduction of the pulse degree is not significant. This article presents a new structure of mechanical pulse CVT—the rotational swashplate pulse CVT with driven by helical gear axial meshing. This transmission is simple and compact in structure and low in pulsatile rate (it adopts 6 guide rods), and the pulsatile degree is irrelevant to the transmission ratio. Theoretically, pulsatile rate could be reduced to zero if appropriate curved surface of the swashplate is used. Compared with the connecting rod pulse CVT, the present structure uses helical gear mechanism as transmission part and it avoids unbalanced inertial force in the former model. This paper analyzes the principle of driving of this transmission, presents its mechanical structure, and discusses its motion characteristics. Experimental prototype of this type of CVT has been manufactured. Tests for the transmission efficiency(when the rotational speed of the output shaft is the maximum) and the angular velocity of the output shaft have been carried out, and data have been analyzed. The experimental results show that the speed of the output shaft for the experimental prototype is slightly lower than the theoretical value, and the transmission efficiency of the experimental prototype is about 70%. The pulse degree of the CVT discussed in this paper is less than the existing pulse CVT of other types, and it is irrelevant to the transmission ratio of the CVT. The research provides the new idea to the CVT study.

Sun, Jiandong; Fu, Wenyu; Lei, Hong; Tian, E.; Liu, Ziping

2012-11-01

72

Transmission line pulse transformers—Theory and applications  

Microsoft Academic Search

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

RICHARD E. MATICK

1968-01-01

73

Identification and characterisation of materials by broadband ultrasonic attenuation analysis  

Microsoft Academic Search

Ultrasound attenuation analysis has been demonstrated as a cheap, reliable method of identifying and characterising polymeric materials and components, which can assist in the separation and reclamation of thermoplastics from polymer waste streams. Material\\/Component broadband ultrasonic attenuation measurement, and the measurement of the time of flight of an ultrasonic pulse, in either pulse echo or pulse through transmission mode, can

J. B. Hull; C. M. Langton; S. Barker; A. R. Jones

1996-01-01

74

Fabrication and characterisation of ?-chitin nanofibers and highly transparent chitin films by pulsed ultrasonication.  

PubMed

?-Chitin nanofibers were fabricated with dried shrimp shells via a simple high-intensity ultrasonic treatment under neutral conditions (60 KHz, 300 W, pH=7). The diameter of the obtained chitin nanofibers could be controlled within 20-200 nm by simply adjusting the ultrasonication time. The pulsed ultrasound disassembled natural chitin into high-aspect-ratio nanofibers with a uniform width (19.4 nm after 30 min sonication). The EDS, FTIR, and XRD characterisation results verified that ?-chitin crystalline structure and molecular structure were maintained after the chemical purification and ultrasonic treatments. Interestingly, ultrasonication can slightly increase the degree of crystallinity of chitin (from 60.1 to 65.8). Furthermore, highly transparent chitin films (the transmittance was 90.2% at a 600 nm) and flexible ultralight chitin foams were prepared from chitin nanofiber hydrogels. PMID:24053832

Lu, Yun; Sun, Qingfeng; She, Xilin; Xia, Yanzhi; Liu, Yixing; Li, Jian; Yang, Dongjiang

2013-11-01

75

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

76

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

77

Responses of Atlantic Salmon Parr to Output of Pulsed Ultrasonic Transmitters  

Microsoft Academic Search

The output from some pulsed ultrasonic transmitters commonly used in fish movement studies is faintly audible to humans. This study was undertaken to determine if the output from these and some other transmitters is detectable by Atlantic salmon (Salmo salar) parr. Classical conditioning of cardiac deceleration was attempted using the transmitter's output as the conditioned stimulus. The results from 29

DOUGLAS E. FACEY; JAMES D. MCCLEAVE; GLEN E. DOYON

1977-01-01

78

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

Microsoft Academic Search

New FDTD algorithm is proposed for analyzing ultrasonic pulse propagation in the human body, the problem being connected with ESWL (Extracorporeal Shock Wave Lithotripsy). In this method, we do not use plane wave approximation but employ directly the original equations taking account of Lagrangian to derive new FDTD algorithms. This method is applied to an experimental setup and its numerical

Keisuke Fukuhara; Nagayoshi Morita

2007-01-01

79

Non-destructive characterization of CMP pads using scanning ultrasonic transmission  

NASA Astrophysics Data System (ADS)

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 the probe are positioned on the moving X-Z stage, while the circular pad is attached to a rotary motor. The probe is aligned with the center of the transmitter and measures with high accuracy and repeatability the amplitude of the transmitted ultrasonic vibrations through the pad at a pre-selected depth in the pad in the contact mode or at a certain elevation above the surface using non-contact mode. The UST system is computer controlled and fully automated. Inhomogeneity of commercial pads with a diameter up to 32'' were revealed and analyzed. Typical UST map exhibits almost regular stripes of high and low acoustic transmission, which are superimposed with global inhomogeneity where the UST amplitude changes circumferentially. Aside from the UST mapping, the system allows for the study of visco-elastic behavior of pad components using UST transient curves. .

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

2001-01-01

80

Pulse elongation and deconvolution filtering for medical ultrasonic imaging  

Microsoft Academic Search

Range sidelobe artifacts which are associated with pulse compression methods can be reduced with a new method composed of pulse elongation and deconvolution (PED). While pulse compression and PED yield similar signal-to-noise ratio (SNR) improvements, PED inherently minimizes the range sidelobe artifacts. The deconvolution is implemented as a stabilized inverse filter. With proper selection of the excitation waveform an exact

Bruno Haider; Peter A. Lewin; Kai E. Thomenius

1998-01-01

81

Ultrasonic guided wave transmission through a geometry transition and NDE of composite-to-adhesive bond  

NASA Astrophysics Data System (ADS)

Ultrasonic guided waves are important tools for inspection of adhesively bonded composites. Mode sensitivity to adhesive defects and conversion at geometry transition are considered when doing mode identification. Matching coefficients are used to prediction energy partition at the transition and compared with transmission coefficients. It verifies that matching coefficients need to combine with phase velocity matching to give reliable prediction. Finally, experiments are carried out using predicted mode-frequency combinations. Peak frequency shifts and amplitude reductions are identified as defect indicators.

Ren, B.; Lissenden, C. J.

2014-02-01

82

Excitation of ultrasonic vibrations in solids by charged-particle pulse beams  

SciTech Connect

The general problem of excitation of ultrasonic vibrations by charged-particle pulse beams is solved for solids with free or rigid surface respectively. General expressions are derived in accordance with the theory of thermoelasticity which describe the space-time structure of acoustic pulses excited by monoenergetic and polyenergetic charged-particle beams. Expressions are also derived for the spectral characteristics of an acoustic pulse and for the efficiency of energy conversion from that of beam particles to acoustic. The results of calculations are illustrated with numerical examples. There follows a discussion concerning the feasibility of effectively using this contactless method of excitation of ultrasonic vibrations for nondestructive inspection (spectroscopy, defectoscopy, and pychometry). 15 references.

Simanchuk, V.I.; Ianisov, V.V.

1984-11-01

83

A pulsed phase measurement ultrasonic flowmeter for medical gases.  

PubMed

Pneumotachometers are used to measure instantaneous flowrate in the respiratory gas streams. The presently available devices suffer from lack of linearity, slow response times, and gas density sensitivity. A new design of an ultrasonic gas flowmeter is presented in this paper: We investigate the acoustic characteristics of ring and piston shaped transducers, and describe a sampling method to avoid the error due to reflection. A microcomputer is used to overcome the 360 degrees detection ambiguity problem associated with phase detection technique. This design has been tested in clinical settings and has been shown to give linear response, independent of gas density, and to have a wide dynamic range. PMID:6240213

Kou, A H; Peickert, W R; Polenske, E E; Busby, M G

1984-01-01

84

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

85

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

86

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

PubMed

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

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

2014-12-15

87

Nano features of Al/Au ultrasonic bond interface observed by high resolution transmission electron microscopy  

SciTech Connect

Nano-scale interfacial details of ultrasonic AlSi1 wire wedge bonding to a Au/Ni/Cu pad were investigated using high resolution transmission electron microscopy (HRTEM). The intermetallic phase Au{sub 8}Al{sub 3} formed locally due to diffusion and reaction activated by ultrasound at the Al/Au bond interface. Multilayer sub-interfaces roughly parallel to the wire/pad interface were observed among this phase, and interdiffusional features near the Au pad resembled interference patterns, alternately dark and bright bars. Solid-state diffusion theory cannot be used to explain why such a thick compound formed within milliseconds at room temperature. The major formation of metallurgical bonds was attributed to ultrasonic cyclic vibration.

Ji Hongjun [Harbin Institute of Technology Shenzhen Graduate School, HIT Campus, Shenzhen University Town, Xili, Shenzhen 518055 (China); State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, 92, Xidazhi Street, Nangang, Harbin 150001 (China); Li Mingyu [Harbin Institute of Technology Shenzhen Graduate School, HIT Campus, Shenzhen University Town, Xili, Shenzhen 518055 (China)], E-mail: myli@hit.edu.cn; Kim, Jong-Myung; Kim, Dae-Won [Jeonnam Provincial College, Jeonnam 517-802 (Korea, Republic of); Wang Chunqing [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, 92, Xidazhi Street, Nangang, Harbin 150001 (China)

2008-10-15

88

On estimating the center frequency of ultrasonic pulses.  

PubMed

In this paper we propose a new technique for estimating the center frequency of the ultrasound pulse from records of backscattering noise. We start by considering that the conventional maximum frequency method can be seen as a filtering (differentiator) of the pulse spectrum magnitude followed by a searching for the zero-crossing value. The new approach replaces the differentiator by a Hilbert transformer. We show in the paper that the proposed method has less variance than the maximum frequency method. In particular, we analyse the performance assuming that the real cepstrum method is used for extracting pulse spectrum magnitude. We give an upper bound for the variance reduction when practical criteria are applied for fitting the cepstrum cut-off frequency. The analytical work is verified by real and simulated data. PMID:15047389

Vergara, L; Gosálbez, J; Miralles, R; Bosch, I

2004-04-01

89

Prospects of pulse phase thermography for finding disbonds in CFRP-sandwich parts with aluminum honeycomb cores compared to ultrasonic  

NASA Astrophysics Data System (ADS)

This work shows the prospects of pulse phase thermography (PPT) compared to ultrasonic testing when applied to carbon fiber reinforced polymer (CFRP) sandwich parts with aluminum honeycomb cores. Measurements were carried out on full-scale components with flaws like disbonds, septum disbonds, staggers and displaced cores, where the last two are not literally flaws, but nevertheless regions of interest. The effect of the measurement time and the feasibility of extrapolating temperature decays were evaluated. Phase images, gathered with PPT, are compared with ultrasonic Cscan images to show the capability of PPT for quality assurance purposes. Finally, the saving on inspection time when using pulse phase thermography instead of ultrasonic testing is considered.

Gruber, J.; Stotter, B.; Mayr, G.; Hendorfer, G.

2013-01-01

90

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

91

ULTRASONIC INSPECTION OF GRAPHITE COMPOSITE AIRCRAFT STRUCTURES  

Microsoft Academic Search

Ultrasonic methods are extensively used for inspecting composite aircraft structures. These inspections play two principal roles: (1) Correction of fabrication and assembly problems through testing of prototype structures. (2) Monitoring of production composite fabrication processes.Through transmission ultrasonic (TTU) systems developed at Boeing for testing secondary aircraft composite components built with honeycomb construction will be described. A pulse-echo (PE) technique developed

WAYNE E. WOODMANSEE

1992-01-01

92

Pulse propagation in composite tubes for ultrasonic evaluation  

NASA Technical Reports Server (NTRS)

Recent revelations about potential EVA times predicted for inspection of large space structures make it clear that any reductions of this time by methods of inspection which may be efficiently implemented remotely are extremely desirable. The work undertaken is the study of detailed 3-D dynamics of the components of the truss assembly (truss tubes and joints) in order to be able to implement an ultrasonic inspection system which may be remotely operated to detect potential problems in the truss assembly such as material degradation or delamination in the truss tubes. Application may also be made to problems of impact response of the truss structure. We report here on the modeling of dynamics of finite composite tubes with dimensions consistent with those of space station tubes. Numerical modeling reported here may be applied to tubes with uniaxial or angle-ply laminae and arbitrary ply lay-ups. For specified time varying tube end conditions, the complete 3-D dynamic response at any position within the tube may be determined first in the frequency domain using a wave propagation based finite element method and the time response is then obtained using a fast Fourier transform. As an application of the method to the problem of material degradation, we consider the alteration in the axial strain time response to changes in material arrival of the elastic waves. In order to demonstrate the 3-D capability of the numerical method, results showing the extent of circumferential/longitudinal motion coupling for different numbers of lamina in 'specially orthotropic' tubes are presented. Decreased coupling for increasing numbers of plies is shown. The capability of capturing this coupling is being investigated as a potential tool for characterizing delamination. The work presented here will be supplemented with modeling of truss joints, integration of the joint and tube models, defect characterization and experimental verification of the modeling procedures.

Kohl, Thomas W.; Datta, Subhendu K.; Shah, Arvind

1990-01-01

93

Ultrasonics  

NASA Technical Reports Server (NTRS)

Ultrasonic testing is discussed as a primary means of nondestructive evaluation of subsurface flaws. The advantages and disadvantages are listed. The elementary principles, basic components of test units, scan modes, resonance testing, detection of fatigue cracks, monitoring fatigue crack growth, and determination of residual stress are discussed.

Leonard, B. E.; Gardner, C. G.

1973-01-01

94

An MMIC Pulse Generator Using Dual Nonlinear Transmission Lines  

Microsoft Academic Search

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

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

2007-01-01

95

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 [Formula: see text] (longitudinal pressure) waves across a stiffener line up with flexural resonances of the stiffener. It also demonstrates why transmission of [Formula: see text] (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

96

A theoretical study of ultrasonic wave transmission through a fluid-solid interface.  

PubMed

This article develops a model for the study of the transient ultrasonic waves radiated by a transducer in a liquid and transmitted into a solid through a plane interface. The method is an extension to the transient case, of the angular spectrum method previously developed for the monochromatic case. It is based on the decomposition of the ultrasonic field, in impulse plane waves. The radiated waveform is calculated at any point in the field by a simple summation of these impulse plane waves, where the propagation delay and the refraction have been taken into account. These plane waves are, first of all, delayed by an amount of time corresponding to the travel time up to the considered field point. The transmission through the plane interface is taken into account by using Snell refraction laws and transmission coefficients. In the obtained results all the waves previously described by other authors are highlighted: direct wave, edge waves, head waves as well as subsurface waves with a clear resolution between compression and shear waves. PMID:18328524

Belgroune, Djema; de Belleval, Jean François; Djelouah, Hakim

2008-07-01

97

Use of tungsten2% thoria ultrasonic transmission line and sensor to improve the performance of high-temperature ultrasonic thermometry  

Microsoft Academic Search

EG and G Idaho Inc. has been involved in the development of the ultrasonic thermometer for use in measuring nuclear fuel rod centerline temperatures. Development efforts have been applied toward increasing the useful range of the device and in preventing the sheath-to-sensor sticking problem which occurs at high temperatures. Classically, high temperatures are determined ultrasonically by measuring the propagation time

A. E. Arave; J. Buchenauer

1976-01-01

98

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

Microsoft Academic Search

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

Lawrence H Ley

99

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

Microsoft Academic Search

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 ,

Lawrence H. Le

1998-01-01

100

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

101

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.

Paredes, Jose A.; Aguilera, Teodoro; Alvarez, Fernando J.; Lozano, Jesus; Morera, Jorge

2011-01-01

102

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

103

Use of Tungsten--2% Thoria Ultrasonic Transmission Line and Sensor to Improve the Performance of High-Temperature Ultrasonic Thermometry.  

National Technical Information Service (NTIS)

EG and G Idaho Inc. has been involved in the development of the ultrasonic thermometer for use in measuring nuclear fuel rod centerline temperatures. Development efforts have been applied toward increasing the useful range of the device and in preventing ...

A. E. Arave J. Buchenauer

1976-01-01

104

Application of the through transmission ultrasonic technique for estimation of the phase velocity dispersion in plastic materials  

Microsoft Academic Search

In many industrial applications through transmission ultrasonic measurements are widely used because they enable to perform characterization and long term monitoring of material properties. The waveform of the signal transmitted through the plastic object usually is distorted due to different factors, such as frequency dependent attenuation, phase velocity dispersion, diffraction, geometry of boundaries and etc. In order to increase the

A. Voleišis; R. Ka

2008-01-01

105

Through-transmission imaging of solids in air using ultrasonic gas-jet waveguides.  

PubMed

An ultrasonic waveguide has been produced in air by using a gas jet. This uses the fact that a lower acoustic velocity can be produced within the jet, relative to the air surrounding it. The lower velocity is achieved by mixing carbon dioxide with air within the jet at a concentration that is a compromise between lower acoustic velocity and increasing attenuation. Using a capacitance transducer placed within the flowing gas, it is shown that improvements in the beam width can result when the gas jet is used. Air-coupled images of solid samples have been produced in through transmission, which demonstrate that an improved lateral resolution can result when a comparison is made to images from conventional air-coupled testing. PMID:14682634

Hutchins, David A; Choi, Doowon; Davis, Lee A J; Gan, Tat-Hean; Billson, Duncan R

2003-11-01

106

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

107

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

108

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

109

Ideal distortion-free transmission using optical Fourier transformation and Fourier transform-limited optical pulses  

Microsoft Academic Search

A new scheme for undistorted ideal pulse transmission is proposed that uses optical Fourier transformation (OFT) and transform-limited (TL) pulses. The technique focuses on the unchanged spectrum of the Fourier TL pulse after transmission, and at the output we convert the unchanged spectrum to the time domain using OFT. The transformed waveform in the time domain has no distortion. To

Masataka Nakazawa; Toshihiko Hirooka; Fumio Futami; Shigeki Watanabe

2004-01-01

110

Experimental characterization of nonlinear transmission lines for amplification of short pulses  

Microsoft Academic Search

Pulse propagation on nonlinear transmission lines (NLTLs), which are transmission lines with regularly spaced Schottky varactors, is experimentally investigated for the am- plification of short pulses. We recently found that the soliton developed in an NLTL experiences an exponential amplitude growth, when it couples with an existing voltage edge. Using a test NLTL, we successfully demonstrate the pulse amplification through

Shun Nakagawa; Koichi Narahara

2011-01-01

111

Reflection and Transmission Behaviors of Ultrasonic Wave at Nano-Air Gap Examined Using Newton's Ring Specimen  

NASA Astrophysics Data System (ADS)

Although in previous studies were examined the ultrasonic reflection behaviors at a nano-air gap using a relatively small optical Newton's ring specimen and a commercial acoustic lens, the details of the quantitative ultrasonic behaviors at a nano-air gap have remained unqualified until now. Since the accuracy of estimating these behaviors is directly related to the accuracy of industrial ultrasonic crack sizing, we tried to measure more accurately quantitative ultrasonic behaviors at a nano-air gap in this study. For this purpose, a special highly focused acoustic lens was designed and fabricated and applied to a large optical Newton's ring specimen to obtain accurate and reliable experimental results. Comparisons between the experimental and the conventional small gap theoretical results for a nano-air gap were also carried out. As a result, ultrasonic transmission was found to begin to occur from 60--70 nm air gaps in all the measurements. This finding was largely different from that based on the gap theory. Regarding the cause of this large difference between the experimental and theoretical results, we also examined the influence of the surface roughness of contact plates.

Inoue, Masaki; Mihara, Tsuyoshi; Tashiro, Hatsuzou; Furukawa, Takashi

2012-07-01

112

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

113

Finite element modeling of ultrasonic waves produced by a pulsed laser  

SciTech Connect

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

Dike, J.J.

1998-03-01

114

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

115

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

Roth, Don J. (Inventor)

1997-01-01

116

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

117

Measurement of guided mode wavenumbers in soft tissue-bone mimicking phantoms using ultrasonic axial transmission  

NASA Astrophysics Data System (ADS)

Human soft tissue is an important factor that influences the assessment of human long bones using quantitative ultrasound techniques. To investigate such influence, a series of soft tissue-bone phantoms (a bone-mimicking plate coated with a layer of water, glycerol or silicon rubber) were ultrasonically investigated using a probe with multi-emitter and multi-receiver arrays in an axial transmission configuration. A singular value decomposition signal processing technique was applied to extract the frequency-dependent wavenumbers of several guided modes. The results indicate that the presence of a soft tissue-mimicking layer introduces additional guided modes predicted by a fluid waveguide model. The modes propagating in the bone-mimicking plate covered by the soft-tissue phantom are only slightly modified compared to their counterparts in the free bone-mimicking plate, and they are still predicted by an elastic transverse isotropic two-dimensional waveguide. Altogether these observations suggest that the soft tissue-bone phantoms can be modeled as two independent waveguides. Even in the presence of the overlying soft tissue-mimicking layer, the modes propagating in the bone-mimicking plate can still be extracted and identified. These results suggest that our approach can be applied for the purpose of the characterization of the material and structural properties of cortical bone.

Chen, Jiangang; Foiret, Josquin; Minonzio, Jean-Gabriel; Talmant, Maryline; Su, Zhongqing; Cheng, Li; Laugier, Pascal

2012-05-01

118

Multiband tissue classification for ultrasonic transmission tomography using spectral profile detection  

NASA Astrophysics Data System (ADS)

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

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

2004-04-01

119

Measurement of guided mode wavenumbers in soft tissue-bone mimicking phantoms using ultrasonic axial transmission.  

PubMed

Human soft tissue is an important factor that influences the assessment of human long bones using quantitative ultrasound techniques. To investigate such influence, a series of soft tissue-bone phantoms (a bone-mimicking plate coated with a layer of water, glycerol or silicon rubber) were ultrasonically investigated using a probe with multi-emitter and multi-receiver arrays in an axial transmission configuration. A singular value decomposition signal processing technique was applied to extract the frequency-dependent wavenumbers of several guided modes. The results indicate that the presence of a soft tissue-mimicking layer introduces additional guided modes predicted by a fluid waveguide model. The modes propagating in the bone-mimicking plate covered by the soft-tissue phantom are only slightly modified compared to their counterparts in the free bone-mimicking plate, and they are still predicted by an elastic transverse isotropic two-dimensional waveguide. Altogether these observations suggest that the soft tissue-bone phantoms can be modeled as two independent waveguides. Even in the presence of the overlying soft tissue-mimicking layer, the modes propagating in the bone-mimicking plate can still be extracted and identified. These results suggest that our approach can be applied for the purpose of the characterization of the material and structural properties of cortical bone. PMID:22538382

Chen, Jiangang; Foiret, Josquin; Minonzio, Jean-Gabriel; Talmant, Maryline; Su, Zhongqing; Cheng, Li; Laugier, Pascal

2012-05-21

120

A theoretical study of ultrasonic wave transmission through a fluid–solid interface  

Microsoft Academic Search

This article develops a model for the study of the transient ultrasonic waves radiated by a transducer in a liquid and transmitted into a solid through a plane interface. The method is an extension to the transient case, of the angular spectrum method previously developed for the monochromatic case. It is based on the decomposition of the ultrasonic field, in

Djema Belgroune; Jean François de Belleval; Hakim Djelouah

2008-01-01

121

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

122

Extraction of anthocyanins from grape by-products assisted by ultrasonics, high hydrostatic pressure or pulsed electric fields: A comparison  

Microsoft Academic Search

Extracts from grape by-products contain bioactive substances such as anthocyanins which could be used as natural antioxidants or colourants. The effect of heat treatment at 70 °C combined with the effect of different emerging novel technologies such as ultrasonics (35 KHz), high hydrostatic pressure (600 MPa) (HHP) and pulsed electric fields (3 kV cm?1) (PEF) showed a great feasibility and selectivity for

M. Corrales; S. Toepfl; P. Butz; D. Knorr; B. Tauscher

2008-01-01

123

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

124

Detection and assessment of wood decay in glulam beams using a through-transmission ultrasonic approach  

NASA Astrophysics Data System (ADS)

A glulam beam retired from the field and without visible indications of wood decay was used. Towards detection and assessing wood decay, X-ray computer tomography and ultrasonic measurements were carried out. It was observed that decrease in mass density with increasing levels of wood decay affects x-rays attenuation and allows radioscopy to detect and assess wood decay. Furthermore, it was also observed that the decrease in mass density and stiffness caused by wood decay affects ultrasonics measurements. It was observed that ultrasonic velocity and stress wave features such as time of arrival, area under the power spectral density curve, energy, and frequency of maximum amplitude allows detection and assessment of wood decay. Results show that results from both X-ray computer tomography and ultrasonic measurements are consistent with each other and can be used to detect and assess wood decay in structural lumber.

Senalik, Adam; Beall, Frank C.; O'Dell, Kristen; Reis, Henrique

2008-05-01

125

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

126

Digital Data Transmission in a Pulse Amplitude Modulation (PAM) Communication System.  

National Technical Information Service (NTIS)

This report presents the results of an experimental evaluation of the effectiveness of digital data transmission in a pulse-amplitude modulation (PAM) communication system. Some sources of PAM system errors are discussed to clarify the nature of the probl...

D. A. King

1975-01-01

127

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

128

Fiber optic picosecond laser pulse transmission line for hydrogen ion beam longitudinal profile measurement.  

PubMed

We present a fiber optic laser pulse transmission line for nonintrusive longitudinal profile measurement of the hydrogen ion (H(-)) beam at the front-end of the Spallation Neutron Source accelerator. The 80.5 MHz, 2.5 ps, multikilowatt optical pulses are delivered to the accelerator beam line through a large-mode-area polarization-maintaining optical fiber to ensure high measurement stability. The transmission efficiency, output laser beam quality, pulse jitter, and pulse width broadening over a 30 m long fiber line are experimentally investigated. A successful measurement of the H(-) beam microbunch (~130 ps) profile is obtained. The experiment is the first demonstration to our knowledge of particle beam profile diagnostics using a fiber optic laser pulse transmission line. PMID:23842239

Huang, Chunning; Liu, Yun; Aleksandrov, Alexander

2013-07-01

129

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

130

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

131

Nonlinear transmission line (NLTL) design as a pulse generator  

Microsoft Academic Search

Computer simulations are performed to optimize the number of sections in a tapered NLTL generating a pulse signal. The Schottky diode model is used based on physical simulation using Silvaco. The extracted CV characteristics are fitted to a hyperbolic function. The effect of the input frequency on the output pulse is investigated

D. Salamh; D. Linton

1996-01-01

132

Monitoring of pulsed ultrasonic waves' interaction with metal continuously heated to the melting point  

NASA Astrophysics Data System (ADS)

A resistance spot welder has been equipped with embedded ultrasonic transducers. Using this setup for ultrasonic data acquisition during welding and a feature analysis promising results are reported. The technology discovers a large potential for nondestructive investigation of thermoelastic behavior of welds. .

Maev, R. Gr.; Ptchelintsev, A.

2001-04-01

133

Studies of ceramic dielectrics for use in high power, pulsed power transmission lines  

Microsoft Academic Search

Summary form only given. The development of compact pulsed power systems has been limited by the materials used in traditional pulsed power accelerators. One approach to decreasing the size of transmission lines would be to use ceramic dielectrics in lieu of traditional plastics or their derivatives. This presentation discusses a collaborative program with a ceramics group that is developing novel

E. Schamiloglu; J. Gaudet; M. Roybal; M. Joler; C. Christodoulou

2003-01-01

134

A Time-Frequency Well-localized Pulse for Multiple Carrier Transmission  

Microsoft Academic Search

In multicarrier transmission schemes, the essential requirement on the elementary pulse or envelope function is the orthogonality with its time-frequency shifted versions. However, the time and frequency dispersion of the mobile radio channel leads to the loss of orthogonality which produces intersymbol interference (ISI) and interchannel interference (ICI). Therefore, another requirement on the elementary pulse has to be imposed: the

Ralf Haas; Jean-Claude Belfiore

1997-01-01

135

Fast high voltage pulse generator with nonlinear transmission line for high repetitive operation  

Microsoft Academic Search

The pulse sharpening effect of nonlinear transmission lines (NLTL) with nonlinear power capacitors has been applied to fast high voltage pulse generation. NLTL can be utilized for high repetitive operation, since NLTL consist of only passive elements. The main problem of the scheme is difficulty of obtaining nonlinear power capacitors with high withstand voltage. In this study, the authors employed

Shinji Ibuka; Takehiro Miyazawa; Akira Ishii; Shozo Ishii

1995-01-01

136

2 THz bandwidth electrical pulses on Au and YBa2Cu3Ox transmission lines  

Microsoft Academic Search

An amorphous photoconductive GaAs switch is laser ablated directly onto a superconducting YBa2Cu3Ox coplanar transmission line structure. Illuminating the switch with femtosecond laser pulses generates electrical pulses containing frequency components up to 2 THz. The pulses are detected by photoconductive sampling and have a full width at half maximum of 0.4 ps without deconvolution. Measurements have been performed on both

Christian J. Osbahr; Britt H. Larsen; Thorsten Holst; Yueqiang Shen

1999-01-01

137

Generation of kilovolt-subnanosecond pulses using a nonlinear transmission line  

Microsoft Academic Search

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

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

1993-01-01

138

Progress in the Study of Folded Blumlein Transmission Lines for Compact Pulsed Power Applications  

Microsoft Academic Search

Abstract One approach tode veloping compactpul sed power drivers ofHi gh Power Microwave (HPM) sourcesi nvolves usingfo ldedB lumleintran smissionlin es as the pulse shaping element. We report on progress int he developmento f these transmission lines. In particular, we report on two aspects of the problem: 1) calculations of the electric field distribution within the transmission line materials, and

Edl Schamiloglu

139

A Pulsed Power Supply Based on Power Semiconductor Switches and Transmission Line Transformer  

Microsoft Academic Search

Transmission line transformers (TLT's) as pulse transformers have received increasingly more attention due to their excellent frequency response characteristics over conventional wound transformers. This transformer basically consists of equal lengths of transmission line (normally coaxial cables are used) connected in parallel at the input side of the transformer, and in series at the output side so that the output voltage

Jian Qiu; Kefu Liu; Yifan Wu

2007-01-01

140

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

141

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

142

Study of Optimum Pulse Transmission through a Dispersion Medium.  

National Technical Information Service (NTIS)

The propagation of electromagnetic signals through ionized media was studied with the goal of relating characteristics of transmitted signals to the physical properties of gaseous plasmas. In particular, methods of optimum transmission were considered usi...

R. E. McIntosh

1973-01-01

143

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

144

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

145

Transmission of solitary pulses in inhomogeneous, nonlinear media: exact solutions  

NASA Astrophysics Data System (ADS)

The dynamics of solitary pulses in an inhomogeneous nonlinear-optical waveguide, and in Bose-Einstein con-densates controlled by means of the Feshback-resonance techniques with a time-dependent magnetic field, which usually includes dispersion and nonlinearity management as typical scenarios, obeys a variable-coefficient non-linear Schrödinger (NLS)/Gross-Pitaevskii (GP) equation. In this paper, we survey approaches that make it possible to identify special cases of such equations that admit families of exact solutions obtained by means of the Hirota bilinear method. In particular, pulse compression and chirp effects are studied by means of this technique. The method is shown to be effective in modeling the evolution and interaction of solitary pulses.

Chow, K. W.; Malomed, Boris A.

2007-08-01

146

ULTRASONIC ECHO-PULSE TOMOGRAPHY OF CONCRETE USING SHEAR WAVES LOW-FREQUENCY PHASED ANTENNA ARRAYS  

Microsoft Academic Search

The paper gives the description of up-to-date metho d for concrete testing based on the dry- point contact ultrasonic transducers technology, ad vanced methods of computer tomography and new techniques of signal processing using SAFT algorithm. The authors explain the operating principles of Low -frequency ultrasonic Tomograph for concrete A1040M MIRA, the main working element of which is 40 DPC

Alexandr V. BISHKO; Andrey A. SAMOKRUTOV; Victor G. SHEVALDYKIN

147

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

148

Pulse Propagation Along Transmission Lines in the Presence of Corona and Their Implication to Lightning Return Strokes  

Microsoft Academic Search

Transmission line equations in air in the presence of corona are derived. The analysis shows that the corona caused by a voltage or a current pulse propagating along a transmission line can be represented by a series of corona current sources distributed along the line. Corona has two effects on the voltage or current pulses propagating along a transmission line.

Vernon Cooray; Nelson Theethayi

2008-01-01

149

Analysis of pulse propagation in coupled microstrip transmission lines  

NASA Astrophysics Data System (ADS)

In this report the problem of propagation of high speed pulses is considered. The purpose of this analysis is to investigate effects such as RC delays, reflection cross-coupling or cross talk, etc., in coupled microstrip lines. Two-, three-, and coupled N-line configurations are considered under various conditions of terminations.

Schutt-Aine, J. E.; Mittra, R.

1985-03-01

150

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

151

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

152

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

153

Acoustic and elastic characterization of marine sediments by analysis, modeling, and inversion of ultrasonic P wave transmission seismograms  

NASA Astrophysics Data System (ADS)

Ultrasonic P wave transmission seismograms recorded on sediment cores have been analyzed to study the acoustic and estimate the elastic properties of marine sediments from different provinces dominated by terrigenous, calcareous, and diatomaceous sedimentation. Instantaneous frequencies computed from the transmission seismograms are displayed as gray-shaded images to give an acoustic overview of the lithology of each core. Centimeter-scale variations in the ultrasonic waveforms associated with lithological changes are illustrated by wiggle traces in detail. Cross-correlation, multiple-filter, and spectral ratio techniques are applied to derive P wave velocities and attenuation coefficients. S wave velocities and attenuation coefficients, elastic moduli, and permeabilities are calculated by an inversion scheme based on the Biot-Stoll viscoelastic model. Together with porosity measurements, P and S wave scatter diagrams are constructed to characterize different sediment types by their velocity- and attenuation-porosity relationships. They demonstrate that terrigenous, calcareous, and diatomaceous sediments cover different velocity- and attenuation-porosity ranges. In terrigenous sediments, P wave velocities and attenuation coefficients decrease rapidly with increasing porosity, whereas S wave velocities and shear moduli are very low. Calcareous sediments behave similarly at relatively higher porosities. Foraminifera skeletons in compositions of terrigenous mud and calcareous ooze cause a stiffening of the frame accompanied by higher shear moduli, P wave velocities, and attenuation coefficients. In diatomaceous ooze the contribution of the shear modulus becomes increasingly important and is controlled by the opal content, whereas attenuation is very low. This leads to the opportunity to predict the opal content from nondestructive P wave velocity measurements at centimeter-scale resolution.

Breitzke, Monika

2000-09-01

154

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

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.

Tantawi, Sami.

1999-02-24

155

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

NASA Astrophysics Data System (ADS)

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 TE_01 mode with negligible mode conversion. In addition, a highly efficient SLED-II^1 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. ^1P.B.Wilson, Z.D.Farkas, and R.D.Ruth, Linear Accel. Conf., Albuquerque, NM, Sept.'90; SLAC-PUB-5330.

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

1997-05-01

156

Electrical short pulses generation using a resonant tunneling diode nonlinear transmission line  

NASA Astrophysics Data System (ADS)

In this paper, the generation of short electrical pulses based on nonlinear active wave propagation effects along the resonant tunneling diode transmission line is studied. The principle of operation is discussed and it is shown by computer experiments that an input rectangular pulse as well as a sinusoidal input signal can be converted into a set of output spikes, suitable for A/D conversion at millimeter wave frequencies.

Essimbi, B. Z.; Jäger, D.

2012-03-01

157

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

158

Pulse sharpening effects of thin film ferroelectric transmission lines  

NASA Astrophysics Data System (ADS)

Advances in material science have resulted in the development of electrically nonlinear high dielectric thin film ferroelectrics, which have led to new opportunities for the creation of novel devices. This dissertation investigated one such device: a low voltage nonlinear transmission line (NLTL). A finite element simulation of ferroelectric transmission lines showed that NLTLs are capable of creating shockwaves. Additionally, if the losses are kept sufficiently low, it was shown that voltage gain should be possible. Furthermore, a method of accounting for material dispersion was developed. Results from simulations including material dispersion showed that temporal solitons might be possible from a continuous ferroelectric based nonlinear transmission line. Fabrication of a thin film ferroelectric NLTL required the growth of a ferroelectric material on a conductive substrate. Barium titanate (BTO), which has been gaining popularity due to its high dielectric constant, strong nonlinearity, and lack of lead, was grown. Molecular beam epitaxy and sol-gel growth were both explored and sol-gel was chosen as the growth method for the final device, in part due to its ability to grow BTO thin films on highly conductive nickel substrates. Samples approximately 330 nm thick were grown by this method. Oxygen vacancies in the as grown BTO films were filled by annealing in low pressure oxygen environments. X-ray diffraction measurements were used to determine an O2 pressure for oxidation that was slightly less than the pressure at which NiO forms to ensure maximum filling of the vacancies in the BTO. Grown samples were successfully shown to have ferroelectric properties. A lumped element transmission line was fabricated using discrete capacitors and inductors with a sample as described above. Test capacitors were fabricated and used to determine the dielectric constant of the BTO thin film. This was used to select capacitor pad sizes and inductor values to create a 50 Ohm line. The substrate was mounted to a chip carrier which was subsequently soldered to a printed circuit board with the appropriate inductors. The device was characterized electrically and the results were compared to the simulation results.

Sleezer, Robert J.

159

Semiconductor mode-locked lasers as pulse sources for high bit rate data transmission  

Microsoft Academic Search

Semiconductor mode-locked lasers are evaluated as pulse sources\\u000afor high bit rate data transmission. This chapter describes the\\u000arequirements of OTDM sources for high bit rate data transmission,\\u000acompares various OTDM source technologies, describes three\\u000asemiconductor mode-locked laser cavity designs, explains the\\u000aimpact of timing jitter and amplitude noise on OTDM performance,\\u000aillustrates how to characterize noise of OTDM sources

Leaf A. Jiang; Erich P. Ippen; Hiroyuki Yokoyama

2005-01-01

160

Ultrasonic Respiration Analysis  

Microsoft Academic Search

We present the design of an ultrasonic respiration analysis system. The system determines the velocity of the respiratory gas flow by measuring absolute transit-times of ultrasonic pulse trains. Besides this standard flow meter function the system computes the 'equivalent molecular weight' M* of the gas flow: M* is calculated by combining the results of the ultrasonic transit-time measurements with temperature

C. Buess; R. Burger; W. Guggenbuhl

1991-01-01

161

Prototype and estimation an ultrasonic motor using a transmission rod with a stator vibrator and a rotor at the both ends  

NASA Astrophysics Data System (ADS)

A new structure of ultrasonic motor composed of a stator vibrator, a rotor and an ultrasonic transmission rod is proposed. Two vibrations of a stator vibrator mounted at a rod end excite two orthogonal bending vibrations in the rod and elliptic motions of displacement are formed at another end of the rod. The elliptic motions produce a rotating force to a rotor pressed at the end. The simple structure of mounting and preloading a rotor is designed by FEM. It is checked experimentally that two orthogonal bending vibrations are excited in the rod and the motor operation of the new construction is confirmed.

Takano, Takehiro; Tamura, Hideki; Sato, Daisuke; Aoyagi, Manabu

2012-05-01

162

Angle-Dependent Ultrasonic Transmission through Plates with Subwavelength Hole Arrays  

NASA Astrophysics Data System (ADS)

We study the angle and frequency dependence of sound transmission through water-immersed perforated aluminum plates. Three types of resonances are found to govern the acoustic properties of the plates: lattice resonances in periodic arrays, Fabry-Perot modes of the hole cavities, and elastic Lamb modes. The last two of them are still present in random arrays and have no parallel in optical transmission through holes. These modes are identified by comparing experiment with various levels of theoretical analysis, including full solution of the elasto-acoustic wave equations. We observe strong mixture of different transmission mechanisms, giving rise to unique acoustic behavior and opening new perspectives for exotic wave phenomena.

Estrada, Héctor; García de Abajo, F. Javier; Candelas, Pilar; Uris, Antonio; Belmar, Francisco; Meseguer, Francisco

2009-04-01

163

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

164

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

NASA Astrophysics Data System (ADS)

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 ? m and the maximum intensity is 2.7× 1019 W/cm2) has been used to measure the light transmitted through thin metal targets. The intensity contrast ratio of the laser pulse was better than 10 - 9 which is low enough to suggest the interaction with solid density plasma without preplasma. We observed the transmittance of the laser pulse through the aluminum foil with thickness up to 4 ? m and found that this radiation is polarized and centered at 0.53 ? m. We found that for 0.8 ? m thick foils the transmission was anomalously high (˜10 - 2 %) and can't be explained by the skin effect for relativistic pulse.

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

2006-06-01

165

Assessment of Effects of Pipe Surface Roughness and Pipe Elbows on the Accuracy of Meter Factors Using the Ultrasonic Pulse Doppler Method  

Microsoft Academic Search

The velocity profile of the flow in a pipe and its influence on the profile factor used with conventional flow meters were investigated with ultrasonic pulse Doppler measurements. From the measured velocity profiles, the influences of surface roughness and Reynolds number were characterized qualitatively and quantitatively. As pipe surface roughness changes during plant operation, the velocity profile changes, producing a

Kenichi TEZUKA; Michitsugu MORI; Takeshi SUZUKI; Masanori ARITOMI; Hiroshige KIKURA; Yasushi TAKEDA

2008-01-01

166

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

167

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

NASA Astrophysics Data System (ADS)

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 ?m 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 intensity contrast ratio of the laser pulses was better than 10-9 which is low enough to suggest the interaction with solid density plasma. We observed the transmittance of the laser pulse through the aluminum foil with thickness up to 4 ?m and found that this radiation is polarized and centered at 0.53 ?m. We found that for 0.8 ?m thick foils the transmission was anomalously high (˜10-4) and can't be explained by the skin effect for relativistic pulse. The performed adaptive grid PIC simulations show good agreement between the calculated transmission coefficient and the experimental transmittance. Energetic electrons produced by the interaction are responsible for the anomalous transmission.

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

2005-10-01

168

The next linear collider test accelerator{close_quote}s RF pulse compression and transmission systems  

SciTech Connect

The overmoded rf transmission and pulsed power compression system for SLAC{close_quote}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 TE{sub 01} mode with negligible mode conversion. In addition, a highly efficient SLED-II [1] pulse compressor has been developed and successfully tested at high power at two accelerator test facilities at SLAC. The systems produced a 200 MW pulse with a near-perfect flat-top with pulse widths ranging from 150{endash}245 ns. In this paper we describe the design and test results of a rectangular-to-circular mode converter and the components/transmission systems based on them, as well as the design and measurements of the high power pulse compression systems using SLED-II. We will also describe how these components are being used to efficiently provide high power rf in the NLC Test Accelerator (NLCTA) program at SLAC. {copyright} {ital 1997 American Institute of Physics.}

Tantawi, S.G.; Vlieks, A.E.; Fant, K.; Lavine, T.; Loewen, R.J.; Pearson, C.; Pope, R.; Rifkin, J.; Ruth, R.D. [Stanford Linear Accelerator Center, 2575 Sand Hill Rd., Menlo Park, California, 94025 (United States)

1997-03-01

169

The next linear collider test accelerator's RF pulse compression and transmission systems  

NASA Astrophysics Data System (ADS)

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 [1] pulse compressor has been developed and successfully tested at high power at two accelerator test facilities at SLAC. The systems produced a 200 MW pulse with a near-perfect flat-top with pulse widths ranging from 150-245 ns. In this paper we describe the design and test results of a rectangular-to-circular mode converter and the components/transmission systems based on them, as well as the design and measurements of the high power pulse compression systems using SLED-II. We will also describe how these components are being used to efficiently provide high power rf in the NLC Test Accelerator (NLCTA) program at SLAC.

Tantawi, S. G.; Vlieks, A. E.; Fant, K.; Lavine, T.; Loewen, R. J.; Pearson, C.; Pope, R.; Rifkin, J.; Ruth, R. D.

1997-03-01

170

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

171

External synchronization of oscillating pulse edge on a transmission line with regularly spaced tunnel diodes  

NASA Astrophysics Data System (ADS)

We investigate the external synchronization of the oscillating pulse edges developed in a transmission line periodically loaded with tunnel diodes (TDs), termed a TD line. It is observed that the pulse edge oscillates on a TD line when supplied by an appropriate voltage at the end of the line. We discuss how the pulse edge oscillates on a TD line and the properties of the external synchronization of the edge oscillation driven by a sinusoidal perturbation. By applying a phase-reduction scheme to the transmission equation of a TD line, we obtain the phase sensitivity, which satisfactory explains the measured spatial dependence of the locking range on the frequency. Moreover, we successfully detect the spatiotemporal behaviors of the edge oscillation by establishing synchronization with the sampling trigger of an oscilloscope.

Narahara, Koichi; Misono, Masatoshi; Miyakawa, Kenji

2013-01-01

172

Responses of transmission-line networks to electrostatic discharge electromagnetic pulses  

NASA Astrophysics Data System (ADS)

A modelling method of transmission-line networks based on Baum-Liu-Tesche (BLT) equation is investigated, and a use of BLT equation for calculating transmission-line load responses in the time domain is discussed. From the frequency-domain BLT equation, the expressions for the propagation function at each terminal load are derived. Using the propagation function and time-domain convolution calculation, the transient load responses in the time domain are gained. For special cases of a dendriform network and an annular network, the transient load responses excited by electrostatic discharge (ESD) pulse are calculated. Compared with test results, and the agreement of the calculation is excellent. The modelling and calculating method could be used to investigate the load responses of transmission-line networks, and estimate the influence of electromagnetic pulses on networks.

Zhou, Xing; Wang, Qingguo; Li, Yang

2013-03-01

173

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

174

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

175

Narrow-band hybrid pulsed laser/EMAT system for noncontact ultrasonic inspection using angled shear waves  

SciTech Connect

Angled, shear wave ultrasonic testing using piezoelectric transducers has been used in industry for years to inspect the plate welds of steel vessels. This method`s reliance on viscous surface couplants limits its reproducibility as well as its applicability for testing surfaces at elevated temperatures. In this work, a pulsed laser/meander line EMAT (electromagnetic acoustic transducer) system was demonstrated to perform testing using vertically polarized, angled, shear waves. This capability was augmented with a narrow-bandwidth laser excitation technique to increase signal-to-noise ratio. The system was tested on both aluminum and steel plates containing saw cuts to mimic cracks. Finally, a steel weld specimen with known defects was tested with good results.

Oursler, D.A.; Wagner, J.W. [Johns Hopkins Univ., Baltimore, MD (United States). Center for Nondestructive Evaluation

1995-05-01

176

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

177

Charge transmission through a molecular junction: Voltage pulse induced transient currents  

NASA Astrophysics Data System (ADS)

The transient response of a single molecule sandwiched between two leads is studied for the case when a single voltage pulse or a sequence of pulses is applied. The theoretical approach focuses on the sequential transmission regime, it accounts for molecular vibrational states and vibrational relaxation, and it utilizes a density matrix approach to compute the current. Charging and discharge rates are presented which adiabatically follow the time-dependent applied voltage. Their improvement to rates which also account for non-adiabatic corrections is discussed. To have a measurable quantity at hand the averaged dc current is computed which results from a huge sequence of single pulses or pulse pairs. The strength of this scheme to get inside in molecular vibrational relaxation upon charging or discharge is highlighted.

Zelinskyy, Yaroslav; May, Volkhard

2014-08-01

178

In vitro comparative study of three devices based on ultrasonic axial transmission  

NASA Astrophysics Data System (ADS)

In the axial transmission technique the velocity of waves propagating in the direction of bone axis is used to characterize cortical bone (radius, tibia, etc.). Corresponding clinically used devices are based on a long wavelength approach (typical frequency around 200 kHz) or shorter wavelength (typical frequency around 1 MHz) compared to bone thickness. They differ also by the methods of wave velocity evaluation. The aim of this study is to compare the sensitivity to bone properties of three representative devices using an in vitro investigation of the same specimens coupled with x-ray determination of bone properties. The moderate correlation between velocities suggests an important impact of site-matching. Among higher frequency devices, the one associated to the bidirectional probe provided generally higher correlation with bone properties than conventional axial transmission. The high-frequency devices are less sensitive to cortical thickness, CSA and trabecular BMD than the low-frequency device because high-frequency waves interrogate a thinner cortical layer than low-frequency waves. Our results suggest that different axial transmission approaches reflect different bone properties. Therefore, a multi-frequency technique might be useful in probing different bone properties at the same time (e.g., cortical thickness and BMD).

Muller, M.; Talmant, M.; Laugier, P.; Moilanen, P.; Kilappa, V.; Timonen, J.; Nicholson, P.; Cheng, S.

2004-10-01

179

In-situ monitoring of asymmetric poly(ethylene-co-vinyl alcohol) membrane formation via a phase inversion process by an ultrasonic through-transmission technique  

Microsoft Academic Search

An ultrasonic through-transmission technique as a novel protocol was developed to monitor asymmetric poly(ethylene-co-vinyl alcohol) (EVAL) membrane formation via the phase inversion process in real-time so as to reveal the relationship between the phase inversion rate and the membrane morphology. The EVAL membrane was prepared with dimethyl sulfoxide (DMSO) as a solvent and water as a nonsolvent at 25°C. The

Ying Cai; Jianxin Li; Yugao Guo; Zhenyu Cui; Yuzhong Zhang

180

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

PubMed

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

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

2012-08-01

181

Ultrasonic Fish Tagging System Development.  

National Technical Information Service (NTIS)

Researchers in the United States, and other countries, are using ultrasonic fish tracking equipment to aid in the study of the habits of individual fish. Most of these systems consist of a pulsed ultrasonic transmitter. Recently at Tennessee Technological...

G. T. Meares J. R. McDearman

1976-01-01

182

Measurement of ultrasonic velocity with improved accuracy in pulse echo setup  

SciTech Connect

In the present work a personal computer based circuit adopted in pulseecho setup has been developed for the measurement of time-of-flight between the two successive echoes using a differential time measurement with a 16 bit counter and an external clock frequency of 32 MHz. A control program is developed in C to display the time of flight and wave propagation velocity on a user screen. The technique, so developed, minimizes the errors in time delay measurements due to the variation in threshold trigger points of echoes and improves the ultrasonic velocity measurement.

Rajagopalan, S.; Sharma, S. J.; Dubey, P. K. [Department of Electronics, R.S.T.M. Nagpur University, Nagpur, Maharastra 440033 (India); Department of Electronics, S.K. Porwal College, Kamptee, Nagpur, Maharashtra 441002 (India); Department of Electronics, R.S.T.M. Nagpur University, Nagpur, Maharastra 440033 (India)

2007-08-15

183

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

NASA Technical Reports Server (NTRS)

Attention is given to a numerical algorithm that, via signal processing, enables the dynamic correction of the shadowing effect of reflections on ultrasonic displays. The algorithm was applied to experimental data from graphite-epoxy composite material immersed in a water bath. It is concluded that images of material defects with the shadowing corrections allow for a more quantitative interpretation of the material state. It is noted that the proposed algorithm is fast and simple enough to be adopted for real time applications in industry.

Kishoni, D.; Heyman, J. S.

1986-01-01

184

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

185

High temperature superconducting Josephson transmission lines for pulse and step sharpening  

SciTech Connect

An increasing number of high speed digital and other circuit applications require very narrow impulses or rapid pulse edge transitions. Shock wave transmission lines using series or shunt Josephson junctions are one way to generate these signals. Using two different high temperature superconducting Josephson junction processes (step-edge and electron beam defined nanobridges), such transmission lines have been constructed and tested at 77 K. Shock wave lines with approximately 60 YBaCuO nanobridges, have generated steps with fall times of about 10 ps. With step-edge junctions (with higher figures of merit but lower uniformity), step transition times have been reduced to an estimated 1 ps.

Martens, J.S.; Wendt, J.R.; Hietala, V.M.; Ginley, D.S.; Ashby, C.I.H.; Plut, T.A.; Vawter, G.A.; Tigges, C.P. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)); Siegal, M.P.; Hou, S.Y.; Phillips, J.M. (AT T Bell Laboratories, Murray Hill, New Jersey 07974 (United States)); Hohenwarter, G.K.G. (Parkview R D, Madison, Wisconsin 53711 (United States))

1992-12-15

186

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

187

Simulation Studies for Nonlinear-Transmission-Line Based Ultrafast Rise Times and Waveform Shaping for Pulsed-Power Applications  

Microsoft Academic Search

The generation of high-voltage electrical pulses with very fast rise times is important for several pulsed-power applications. Although several techniques and devices have been used to generate ultrashort rise-time pulses, most suffer from problems relating to reliability, lifetime, and power-handling capacity. Here, the concept of using nonlinear transmission lines is used for attaining ultrashort rise times and pulse sharpening. Numerical

G. Zhao; R. P. Joshi; S. Rogers; E. Schamiloglu; H. P. Hjalmarson

2008-01-01

188

Pulse-transmission Oscillators: Autonomous Boolean Models and the Yeast Cell Cycle  

NASA Astrophysics Data System (ADS)

Models of oscillatory gene expression typically involve a constitutively expressed or positively autoregulated gene which is repressed by a negative feedback loop. In Boolean representations of such systems, which include the repressilator and relaxation oscillators, dynamical stability stems from the impossibility of satisfying all of the Boolean rules at once. We consider a different class of networks, in which oscillations are due to the transmission of a pulse of gene activation around a ring. Using autonomous Boolean modeling methods, we show how the circulating pulse can be stabilized by decoration of the ring with certain feedback and feed-forward motifs. We then discuss the relation of these models to ODE models of transcriptional networks, emphasizing the role of explicit time delays. Finally, we show that a network recently proposed as a generator of cell cycle oscillations in yeast contains the motifs required to support stable transmission oscillations.

Sevim, Volkan; Gong, Xinwei; Socolar, Joshua

2010-03-01

189

Quasi-linear optical pulses in strongly dispersion-managed transmission systems.  

PubMed

A unified analytical description of the evolution of quasi-linear optical pulses and solitons in strongly dispersion-managed transmission systems is developed. Asymptotic analysis of the nonlocal equation that describes the averaged dynamics of a dispersion-managed system shows that the nonlinearity decreases for large map strength s , as O(log s/s) . The spectral intensity is found to be an invariant of the propagation, which allows the phase shift to be computed. These findings provide a clear description of pulse propagation in the quasi-linear regime, which is characterized by much lower energies than those required for stable dispersion-managed soliton transmission with the same dispersion map. PMID:18040353

Ablowitz, M J; Hirooka, T; Biondini, G

2001-04-01

190

Detection of broadband laser induced longitudinal ultrasonic pulses in ultrafine grain nickel by pancake coil  

NASA Astrophysics Data System (ADS)

Broadband longitudinal pressure pulses induced by 5 ns laser pulse were used to evaluate bulk nickel with gradually changing microstructure from polycrystalline to ultrafine grain microstructure. This microstructure was generated by severe plastic deformation using the high pressure torsion method. A permanent cylindrical magnet and a pancake coil were attached at one side of the nickel specimen, allowing the detection of magnetic field variations induced by probe pressure pulse generated at the opposite side. The ultrafine grain structure demonstrated lower attenuation in comparison with polycrystalline microstructure where the scattering of the ultrasound was significant. In cases of acoustically free and impedance border the spectra of the primary pulses covered the range from 5 MHz up to 200 MHz.

Kozhushko, Victor V.; Krenn, Heinz; Pippan, Reinhard

2012-05-01

191

Effects of dispersion in transmission of FBG in DWDM system on adjacent channel pulse shape  

Microsoft Academic Search

In future high bit-rate DWDM systems, the channel separations will be narrower and the bit-rate of single channel will be higher. The dispersion in transmission of fiber Bragg gratin is a factor that cannot be neglected. We emphasize the effects of the 3rd order dispersion because the 3rd order dispersion is more detrimental for short pulses than the 2nd order

Yong Guo; Yongqing Huang; Jien Song; Xue Chen; Xiaomin Ren

2002-01-01

192

Transmission improvement in ultralong dispersion-managed soliton WDM systems by using pulses with different widths  

Microsoft Academic Search

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

T. I. Lakoba

2005-01-01

193

Design of pulsed waveform oscillators with a short nonlinear transmission line  

Microsoft Academic Search

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

Mabel Ponton; Franco Ramirez; Almudena Suarez

2010-01-01

194

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

Microsoft Academic Search

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

D. Salameh; D. Linton

1999-01-01

195

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

PubMed

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

Chen, Ziqiang; Yang, Lin

2011-01-01

196

Pulse compression with volume holographic transmission gratings recorded in Slavich PFG-04 emulsion  

NASA Astrophysics Data System (ADS)

In this work we design and construct a pulse compressor with volume transmission holographic gratings, to compensate the second order dispersion in femtosecond laser pulses emitting at 794 nm with a spectral broadband of 10 nm. The gratings (730 lines/mm) are recorded in PFG-04 dichromated gelatine emulsion with a wavelength of 532 nm, reaching enough index modulation to use the gratings illuminated with 800 nm light source with high efficiency (around 80% of efficiency in each grating). This efficiency is expected to be increased with an antireflection coating. We measure the factor of compression as a function of the grating distance using an autocorrelator, finding a good agreement with theoretical curve. A dispersed pulse (580 fs) is reduced to the bandwidth limited value of 106 fs with the grating pair separated by 27 mm.

Villamarín, Ayalid; Sola, Íñigo; Atencia, J.; Collados, M. V.; Arias, I.; Mendez, C.; Varela, O.; Alonso, B.; Rodríguez, J.; Quintanilla, M.; Roso, L.

2009-08-01

197

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

198

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

199

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

200

DC power transmission system of voltage source converter using pulse-interleaving auxiliary circuit  

US Patent & Trademark Office Database

A DC power transmission system of a voltage source converter using a pulse-interleaving auxiliary circuit is disclosed. The converter system comprises an IGBT converter for converting an AC power to a DC power or the DC power to the AC power; an open Y-Y transformer and a Y-.DELTA. transformer for stepping up or stepping down the AC power having a predetermined magnitude; a capacitor for dividing a DC voltage; and a DC Auxiliary circuit composed of a normal transformer and half-bridge for overlapping a pulse type input voltage to increase the number of pulses of an output waveform. In using a DC auxiliary circuit composed of normal transformer and 3-level half-bridge to increase the number of pulses of the output waveform by superposing the voltage in the form of the pulse, a normal transformer may be used instead of the tapped transformer to reduce the size thereof and to obtain an accurate transformer ratio, and a 3-level half-bridge may be used instead of the H-bridge to reduce the switching loss.

2009-03-03

201

Dark soliton synthesis using an optical pulse synthesizer and transmission through a normal-dispersion optical fiber.  

PubMed

We precisely generate dark solitons using an optical pulse synthesizer (OPS) at a repetition rate of 25 GHz and experimentally investigate soliton transmission through a normal-dispersion fiber. Because of their particular waveform, there are not many experimental studies. The OPS provides frequency-domain line-by-line modulation and produces arbitrary pulse waveforms. The soliton waveform has an intensity contrast greater than 20 dB. At certain input peak power, the pulse exhibits soliton transmission and maintains its initial waveform. The power agrees with soliton transmission theory. We confirm that the ? phase shift at the center of the dark soliton is maintained after transmission through the fiber. We also investigate the influence of stimulated Brillouin scattering for long-distance transmission. PMID:24514661

Kashiwagi, Ken; Mozawa, Kiyonobu; Tanaka, Yosuke; Kurokawa, Takashi

2013-12-16

202

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

203

Influence of spatial sampling on the ultrasonic pulse-echo BEEI-mode imaging technique  

NASA Astrophysics Data System (ADS)

Defects in the seal area of flexible packages bring out health hazards and economic loss. The ultrasonic Backscattered Echo Envelope Integral (BEEI) imaging technique has been used to detect the seal integrity of hermetically sealed flexible packages. This technique was able to reliably inspect channel defects as small as 50?m in diameter in the seal area of flexible packages. The study of experimental spatial sampling for the BEEI-mode imaging technique was presented. Channel defects ranging from 50 to 150?m in diameter embedded in bonded 2-sheet polyethylene film were used for sample. An immersion spherically focused transducer (center frequency of 22.66 MHz) scanned over sample with a static rectilinear stop-and-go scanning pattern and acquired echo data in varying scanning step from each sample. Two descriptors, the average BEEI value difference (?BEEI) between defected and intact regions and contrast-to-noise ratio (CNR), were defined to quantitatively assess the BEEI-mode image quality versus varying scanning step size and varying sized defects. For any given defects, the ?BEEI and CNR degraded as scanning step size increased. Detailed imaging of defects can be acquired when the step size is small than echo focal beam diameter, and the image become partial or completely distorted when the step size exceeds twice of the beam diameter.

He, Cunfu; Yuan, Hongmei; Wu, Bin

2008-11-01

204

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

205

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

PubMed

A method using pulse echo ultrasound and the Kalman filter is developed for detecting submicron harmonic motion induced by ultrasonic radiation force. The method estimates the amplitude and phase of the motion at desired locations within a tissue region with high sensitivity. The harmonic motion generated by the ultrasound radiation force is expressed as extremely small oscillatory Doppler frequency shifts in the fast time (A-line) of ultrasound echoes, which are difficult to estimate. In slow time (repetitive ultrasound echoes) of the echoes, the motion also is presented as oscillatory phase shifts, from which the amplitude and phase of the harmonic motion can be estimated with the least mean squared error by Kalman filter. This technique can be used to estimate the traveling speed of a harmonic shear wave by tracking its phase changes during propagation. The shear wave propagation speed can be used to solve for the elasticity and viscosity of tissue as reported in our earlier study. Validation and in vitro experiments indicate that the method provides excellent estimations for very small (submicron) harmonic vibrations and has potential for noninvasive and quantitative stiffness measurements of tissues such as artery. PMID:17328326

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

2007-02-01

206

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

207

FDTD and SPICE Simulations for Lossy and Dispersive Nonlinear Transmission Lines Used for Pulse Compression : a Comparison  

Microsoft Academic Search

For the first time, we demonstrate the simulation of lossy and dispersive non linear transmission lines (NLTLs) used for pulse compression, by two different time-domain approaches: SPICE and a full wave 3D FDTD. Results show a good agreement between the two approaches. Output pulse risetime is very affected by DC and skin-effect losses.

A. Jrad; W. Thiel; P. Ferrari; J. W. Tao

2000-01-01

208

Development of material evaluation method by using a pulsed neutron transmission with pixel type detectors  

NASA Astrophysics Data System (ADS)

A spectroscopic neutron imaging is attractive in the research field of energy-selective neutron radiography. Imaging using the time-of-flight (TOF) method at a pulsed neutron source is very suitable for such spectroscopic measurements. We developed new two-dimensional position sensitive neutron detectors (2D-PSNDs) aiming at high detection efficiency, high counting rate and high time resolution which are the most important 2D-PSND performances for the spectroscopic imaging. These detectors consist of independent 6Li-glass (Ce) scintillator pixels, and have been used in various pulsed neutron transmission experiments. As a result, we have succeeded in developing various new imaging techniques; crystallographic, nuclide-selective and thermographic imaging.

Sato, H.; Takada, O.; Satoh, S.; Kamiyama, T.; Kiyanagi, Y.

2010-11-01

209

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

210

Comparison of the optical transmission properties of pulsed and continuous wave light in biological tissue  

SciTech Connect

The purpose of this study is to compare the optical transmission of the pulsed gold vapor laser (628 nm) to that of the continuous wave argon-pumped dye laser (630 nm) in a homogenous tissue model. Gluteal muscle was taken from a rabbit, and sections of varying thicknesses were made. The tissue samples were positioned at the aperture of an integrating sphere. The laser light was passed through an optical attenuator, coupled to a 600-microns fiber, and then directed onto the surface of the tissue. Transmitted light was collected by the integrating sphere. Light measurements were made with a radiometer. This procedure was repeated for samples of differing thickness using the gold vapor laser as the light source. The identical procedure was performed using the argon-pumped dye laser. No significant difference was found in percent transmission of light using the gold vapor laser as compared to the argon-pumped dye laser.

LaPlant, M.; Parker, J.; Stewart, B.; Waner, M.; Straight, R.C.

1987-01-01

211

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

212

Photoconductor pulse generators and sampling gates for characterization of high-speed devices and transmission lines  

SciTech Connect

We describe photoconductive semiconductor devices developed for application in diagnostics of high-speed electronic devices and circuits. Both pulse generation and sampling functions are provided by these ultrafast photoconductors. The photoresponse of different semiconductor materials (GaAs, InP, Si) that have been ion bombarded (Ar, H, He, Ne, O, Si) was investigated and characterized. Response times as short as 1 picosecond have been observed. High frequency propagation characteristics of microstrip and coplanar waveguide transmission lines have been studied and modelled. Application of this measurement technique to the characterization of a microwave GaAs transistor is presented.

Paulter, N.G.; Hammond, R.B.

1987-01-01

213

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

214

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

215

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

216

An all solid-state high-voltage ns trigger generator based on magnetic pulse compression and transmission line transformer.  

PubMed

Innovative design of an all solid-state high-voltage ns trigger generator, based on magnetic pulse compression and transmission line transformer, is presented. The repetitive trigger pulse generator was developed to trigger a 700 kV trigatron, which has been used to pulse a repetitive intense electron beam accelerator with Tesla transformer charged double pulse forming lines (PFLs). Experimental results show that the trigger pulse generator could produce 180 kV 65 ns duration pulses with a rise time of 20 ns. The repetitive trigger pulses have nice uniform in the voltage waveform. The control time jitter is less then 3 ns. Owing to its good stability and low time jitter, the high-voltage trigger generator is an excellent candidate to trigger the repetitive accelerator. PMID:24089822

Lin, Jiajin; Yang, Jianhua; Zhang, Jiande; Chen, Xinbing

2013-09-01

217

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

218

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

219

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

220

Numerical analysis of the hybrid transducer ultrasonic motor: comparison of characteristics calculated by transmission-line and lumped-element models.  

PubMed

In this paper, a hybrid transducer ultrasonic motor is numerically analyzed by using two equivalent electrical circuit models. A transmission-line model for the torsional vibration in the stator, which can model any torsional vibration mode and their combinations, was introduced and compared with a lumped-element model, which modeled the fundamental torsional resonance mode in the stator. The calculation result by using the transmission-line model demonstrated that the second harmonic torsional vibration increased either with the static spring force by which the rotor was pressed to the stator or with the load torque placed on the rotor. The difference in the calculated motor performance between the two models appeared when the second harmonic torsional vibration became large at a sufficient static spring force. PMID:12109546

Satonobu, Jun; Friend, James R; Nakamura, Kentaro; Ueha, Sadayuki

2002-06-01

221

Load resilient transmission line system for long-pulse, high-power ICRF operation at KSTAR  

NASA Astrophysics Data System (ADS)

We have newly designed, fabricated, and installed a decoupler and a 3 dB hybrid coupler for load-resilient operation of the KSTAR ICRF. The new ICRF TL system for load resilient operation has been successfully performed in 2012 plasma experiments. In L-mode plasmas, the ratio between two powers measured at the isolated port of the hybrid coupler and reflected from two resonant loops becomes approximately 1. Furthermore, a load resilient transmission line (TL) system results in stable ICRF transmitter operation and power transmission in ELMy discharges. The maximum ICRF transmitted power is approximately 500 kW and pulse length is 3 s. With power transmission at higher than 500 kW, breakdowns frequently occurred in the vacuum feedthrough. After the campaign, we discovered that surfaces of alumina, coaxial inner and outer conductor of the vacuum feedthrough were severely damaged by the arcs. We removed the silver coat from 8 feedthroughs and repaired the damaged surfaces. In order to study a higher standoff capability, we tested the repaired feedthroughs in the vacuum chamber with a high power RF test stand.

Kim, H. J.; Wang, S. J.; Bae, Y. S.; Yang, H. L.; Kwak, J. G.; Kim, S. H.; Park, M.; Kstar Team

2014-02-01

222

Simulation Analysis of Transmission-Line Impedance Transformers for Petawatt-Class Pulsed Power Accelerators  

NASA Astrophysics Data System (ADS)

Based on the transmission line code TLCODE, a 1D circuit model for a transmission-line impedance transformer was developed and the simulation results were compared with those in the literature. The model was used to quantify the efficiencies of voltage-transport, energy-transport and power-transport for a transmission-line impedance transformer as functions of ? (the ratio of the output impedance to the input impedance of the transformer) and ? (the ratio of the pulse width to the one-way transit time of the transformer) under a large scale of m (the coefficient of the generalized exponential impedance profile). Simulation results suggest that with the increase in ?, from 0 to ?, the power transport efficiency first increases and then decreases. The maximum power transport efficiency can reach 90% or even higher for an exponential impedance profile (m = 1). With a consideration of dissipative loss in the dielectric and electrodes of the transformer, two representative designs of the water-insulated transformer are investigated for the next generation of petawatt-class z-pinch drivers. It is found that the dissipative losses in the electrodes are negligibly small, below 0.1%, but the dissipative loss in the water dielectric is about 1% to 4%.

Hu, Yixiang; Sun, Fengju; Huang, Tao; Qiu, Aici; Cong, Peitian; Wang, Liangping; Zeng, Jiangtao; Li, Yan; Zhang, Xinjun; Lei, Tianshi

2011-08-01

223

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

224

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

225

Transmission line based short pulse generation circuits in a 0.13 ?m complementary metal-oxide-semiconductor technology.  

PubMed

A few traditional pulse forming circuits are implemented and compared in a commercial 0.13 ?m digital CMOS technology. Standard on-chip transmission lines are used as pulse forming lines (PFLs), while CMOS transistors are used as switches. The shortest output pulses of these circuits are analyzed and compared through Cadence Spectre simulations. All the CMOS circuits are fabricated in the commercial technology. Pulses of ?170 ps durations and 120-400 mV amplitudes are obtained when the power supply is tuned from 1.2 to 2 V. The results show that these traditional PFL based circuits can be implemented in standard CMOS technology for high power short pulse generations. Furthermore, the PFL circuits significantly extend the short pulse generation capabilities of CMOS technologies. PMID:21361585

Zou, Huan; Geng, Yongtao; Wang, Pingshan

2011-02-01

226

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

227

Compensation of second-order dispersion in femtosecond pulses after filamentation using volume holographic transmission gratings recorded in dichromated gelatin  

NASA Astrophysics Data System (ADS)

We have designed and developed a pulse compressor with volume transmission holographic gratings to be implemented in post-compression experiments based on filamentation in gases. Pulse compression down to 13 fs has been demonstrated. The gratings have been recorded in commercial PFG-04 dichromated gelatin emulsions with a recording wavelength of 532 nm, attaining sufficient index modulation to achieve high efficiency when they are illuminated by an 800-nm laser.

Villamarín, A.; Sola, I. J.; Collados, M. V.; Atencia, J.; Varela, O.; Alonso, B.; Méndez, C.; San Román, J.; Arias, I.; Roso, L.; Quintanilla, M.

2012-01-01

228

Fiber Bragg gratings for dispersion compensation in transmission: theoretical model and design criteria for nearly ideal pulse recompression  

Microsoft Academic Search

We propose a transmission-based dispersion compensator employing an apodized, unchirped fiber Bragg grating (FBG). A theoretical model for dispersion compensation in transmission based on the dispersive properties of the periodic structure is developed. A figure of merit is defined for optimization of the grating parameters for maximum recompression of dispersion-broadened optical pulses in long-haul communication systems. Numerical examples confirm that

Natalia M. Litchinitser; Benjamin J. Eggleton; David B. Patterson

1997-01-01

229

Fundamental study of an electric power transmission system for implanted medical devices using magnetic and ultrasonic energy  

Microsoft Academic Search

In this paper, the authors propose a novel electric power supply system for implanted medical devices. The system is noninvasive\\u000a and uses two kinds of energy, magnetic and ultrasonic. The system can provide high power levels harmlessly. The energies are\\u000a obtained by two types of vibrator, i.e., piezo and magnetostriction devices. A prototype was built and it was verified experimentally

Shin-nosuke Suzuki; Tamotsu Katane; Osami Saito

2003-01-01

230

Effects of dispersion in transmission of FBG in DWDM system on adjacent channel pulse shape  

NASA Astrophysics Data System (ADS)

In future high bit-rate DWDM systems, the channel separations will be narrower and the bit-rate of single channel will be higher. The dispersion in transmission of fiber Bragg gratin is a factor that cannot be neglected. We emphasize the effects of the 3rd order dispersion because the 3rd order dispersion is more detrimental for short pulses than the 2nd order dispersion. Furthermore, the 3rd order dispersion is always positive whether the wavelength of the adjacent channel is longer than Bragg wavelength or not. So the accumulated effects are more notable than the 2nd order dispersion, which can be positive or negative. We calculated the effects of the dispersion of FBG on pulses with 1ps, 2ps and 5ps widths under channel separations of 50GHz and 100GHz. It is shown the 3rd order dispersion will be more detrimental in high bit-rate DWDM systems. This paper will gives more guide to FBG design for ADM application. The method we use is split-system Fourier Method.

Guo, Yong; Huang, Yongqing; Song, Jien; Chen, Xue; Ren, Xiaomin

2002-08-01

231

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

PubMed

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

Burdt, R; Curry, R D

2007-07-01

232

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

233

High-Altitude Electromagnetic Pulse Simulation Test on Northern Telecom Inc. FD-565 Optical Fiber Transmission System.  

National Technical Information Service (NTIS)

This report describes the tests on the Northern Telecom Inc. (NTI), FD-565 Optical Fiber Digital Transmission System against the high-altitude electromagnetic pulse (HEMP). It contains the information presented in NCSTIB-91-1 and HDL SR-91-8 along with th...

E. Nguyen M. H. Mar R. J. Reyzer

1997-01-01

234

Fundamental study of an electric power transmission system for implanted medical devices using magnetic and ultrasonic energy.  

PubMed

In this paper, the authors propose a novel electric power supply system for implanted medical devices. The system is noninvasive and uses two kinds of energy, magnetic and ultrasonic. The system can provide high power levels harmlessly. The energies are obtained by two types of vibrator, i.e., piezo and magnetostriction devices. A prototype was built and it was verified experimentally that the system is basically able to provide power. At high frequencies, such as 100 kHz, the output power was higher than the conventional system using a transformer. The normalized output power per unit volume also exceeded the transformer system. PMID:14598116

Suzuki, Shin-nosuke; Katane, Tamotsu; Saito, Osami

2003-01-01

235

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

236

Ultrasonic meters prove reliability on Nova Gas pipeline  

SciTech Connect

Getting the job done efficiently, safely, and economically are the main reasons Nova Gas Transmission Ltd. (NGTL) of Alberta, Canada looked to an ultrasonic gas flow meter for its flow measurement applications. In the past, NGTL relied mainly on orifice plates to measure mainline flow. In 1990, as a result of an increased requirement for reliable mainline measurement, NGTL initiated a Mainline Measurement Task group to review available metering devices and recommend the best solution. This task group compiled a list of acceptance criteria against which to assess various options. They were looking for mainline measurement devices with high accuracy and performance. After developing the acceptance criteria and researching other pipeline companies in North America and Europe, the Task Group narrowed the list of options to four measurement devices, including two single-path ultrasonic meters. Further evaluation conducted at NGTL`s research facility concluded that the single-path ultrasonic gas flow meter was best suited for NGTL`s system requirements. The single-path ultrasonic gas flow meter, selected by the Task Group, uses direct digital time measurement of the difference between travel times of individual upstream and downstream ultrasonic pulses. This paper reviews the complexity of flow measurements and the types of information that is necessary to accurately calculate flow. The performance and accuracy of the ultrasonic meter are provided based on this company`s experience.

Rogi, M. [Nova Gas Transmission Ltd., Calgary, Alberta (Canada)

1995-08-01

237

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

238

Improvement in the Identification of a Crack Tip Echo in Ultrasonic Inspection using Large Displacement Ultrasound Transmission  

NASA Astrophysics Data System (ADS)

As an improvement in the imaging technique for the low S/N ratio of crack tip echo in ultrasonic inspection, we developed the Subharmonic Phased Array Crack Evaluation (SPACE) system. Although the pulser of conventional SPACE can generate large, over tens of nm, displacement ultrasound at a crack, it is effective only for closed cracks and not effective for most industrial cracks. For general use of the SPACE system in industrial inspection, we need to develop larger displacement ultrasound incidence equipment considering crack openings of the order of several nm to sub ?m. In this study, we developed a high voltage excitation SPACE and larger amplitude ultrasound incident to a crack using a high voltage proof transducer. The suitability of the developed system was investigated using typical models of cracks.

Mihara, T.; Ishida, H.

2014-06-01

239

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

240

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 µm) 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 µm. 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

241

Ferroelectret non-contact ultrasonic transducers  

NASA Astrophysics Data System (ADS)

Dielectric and electromechanical properties of the cellular polypropylene ferroelectret films (EMFIT), combining strong piezoelectric response with a low density and softness, evidence their high potential for the air-coupled ultrasonic applications. The disadvantage of the low coupling factor is compensated by the extremely low acoustic impedance, which provides excellent matching to air and promises efficient sound transmission through the air transducer interface. The influence of the electrodes on the electromechanical properties was investigated. Electron beam evaporation technology was adapted to the EMFIT films, and films with both-sided Au and Al electrodes were prepared without reducing or suppressing of the electromechanical properties. Finally, prototype transducers based on the EMFIT films were developed. In spite of the simple construction and absence of matching layers, high sensitivity of the EMFIT transducers was proved in the air-coupled ultrasonic experiment. Amplitude and delay time scanned images of the polyethylene step wedge with holes, obtained in both pulse-echo and transmission modes, demonstrate that non-contact ultrasonic imaging and testing with EMFIT transducers is possible.

Bovtun, V.; Döring, J.; Bartusch, J.; Beck, U.; Erhard, A.; Yakymenko, Y.

2007-09-01

242

Bibliography on Ultrasonic Delay Lines  

Microsoft Academic Search

.. .. .. -. of wave propagation in bounded elastic solids and with the basic elements of ultrasonic delay lines and the equivalent circuit; second, material relating to the means by which ultrasonic waves are generated, the electromechanical transducer; third, material relating to the transmission medium, principally vitreous silica, aluminum, magnesium, iso-elastic metal alloys, and, to some extent, mercury; and

M. D. Fagen

1954-01-01

243

Systematic variation of parametrically shaped sub-pulse sequences after transmission through a photonic crystal fiber  

NASA Astrophysics Data System (ADS)

We present an analytical concept for generating shaped femtosecond laser pulses at the distal end of a microstructured hollow core photonic crystal fiber. The properties of the fiber are analyzed and included in the shaping procedure. A parametric pulse shaping method allows for tailoring a sequence of sub-pulses. In this method, each sub-pulse can be individually controlled by its physically intuitive parameters distance in time, energy, phase and chirps as well as the state of polarization including ellipticity, orientation, and helicity. This is demonstrated with a series of double pulses, in which a single parameter is systematically varied, and additionally with more complex example pulses. Further, we investigate the impact of mechanical distortions of the fiber on the pulse shape. The presented method could be beneficially used in endoscopic applications in life sciences.

Weise, Fabian; Achazi, Georg; Paw?owska, Monika; Lindinger, Albrecht

2011-07-01

244

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

245

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  

NASA Astrophysics Data System (ADS)

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.; Kim, G.-H.; Hotta, E.

2010-04-01

246

Ultrasonic Relaxation in Aqueous Acetic Acid Solutions.  

National Technical Information Service (NTIS)

Ultrasonic absorption measurements have been made in aqueous acetic solutions at 15 to 85 MHz using pulse echo and pulse send-receive techniques. A weighted nonlinear regression method has been developed for the computation of the relaxation parameters. A...

L. G. Jackopin E. Yeager

1971-01-01

247

Effect of bone cortical thickness on velocity measurements using ultrasonic axial transmission: A 2D simulation study  

NASA Astrophysics Data System (ADS)

In recent years, quantitative ultrasound (QUS) has played an increasing role in the assessment of bone status. The axial transmission technique allows to investigate skeletal sites such as the cortical layer of long bones (radius, tibia), inadequate to through-transmission techniques. Nevertheless, the type of propagation involved along bone specimens has not been clearly elucidated. Axial transmission is investigated here by means of two-dimensional simulations at 1 MHz. We focus our interest on the apparent speed of sound (SOS) of the first arriving signal (FAS). Its dependence on the thickness of the plate is discussed and compared to previous work. Different time criteria are used to derive the apparent SOS of the FAS as a function of source-receiver distance. Frequency-wave number analysis is performed in order to understand the type of propagation involved. For thick plates (thickness>lambdabone, longitudinal wavelength in bone), and for a limited range of source-receiver distances, the FAS corresponds to the lateral wave. Its velocity equals the longitudinal bulk velocity of the bone. For plate thickness less than lambdabone, some plate modes contribute to the FAS, and the apparent SOS decreases with the thickness in a way that depends on both the time criterion and on the source-receiver distance. The FAS corresponds neither to the lateral wave nor to a single plate mode. For very thin plates (thicknessbone)/4, the apparent SOS tends towards the velocity of the lowest order symmetrical vibration mode (S0 Lamb mode). copyright 2002 Acoustical Society of America.

Bossy, Emmanuel; Talmant, Maryline; Laugier, Pascal

2002-07-01

248

Acoustic Transmission Loss and Pulse Time-Spread Measured Off the South Carolina Coast During the 1997 Littoral Warfare Advanced Development System Concept Validation Experiment.  

National Technical Information Service (NTIS)

Acoustic transmission loss and pulse time-spread measurements were performed off the South Carolina coast as part of the Littoral Warfare Advanced Development (LWAD) environmental measurement support provided for the 1997 System Concept Validation (SCV 97...

B. Pasewark A. Al-Kurd

1998-01-01

249

Asymptotic Theory of the Reflection and Transmission of a Pulsed Electromagnetic Beam Field at a Planar Interface Separating Two Dispersive Media.  

National Technical Information Service (NTIS)

Our long-term research goal is to develop a rigorous analytic formulation and, uniform asymptotic description of pulsed electromagnetic beam-field propagation, reflection, and transmission phenomena in causally dispersive dielectric and conducting media. ...

K. E. Oughstun

1997-01-01

250

Simulations of laser pulse coupling and transmission efficiency in plasma channels  

Microsoft Academic Search

The guiding of intense laser pulses in plasma channels is necessary to maximize the energy of electrons accelerated in a laser wakefield accelerator. A significant fraction of the energy in the laser pulse may be lost during and after coupling from vacuum into a channel. For example, imperfect coupling can lead to enhanced leakage of laser energy transversely through the

D. A. Dimitrov; D. B. Bruhwiler; J. R. Cary; P. Messmer; C. Geddes; E. Esarey; W. Leemans

2004-01-01

251

Effect of a CO2 laser pulse on transmission through fog at visible and IR wavelengths  

NASA Astrophysics Data System (ADS)

The extinction coefficients of laboratory generated fog at 0.63 and 10.6 microns are monitored during and after passage of a coaxial CO2 laser pulse of 2-J/sq cm fluence. Pulse passage causes a slight decrease in extinction at 10.6 microns and a marked increase in this quantity at 0.63 micron. This effect is consistent with the significant reduction in fog droplet size, caused by absorption of energy from the pulse. The data are analyzed to provide the time dependence of particle size following pulse passage, and the inferred particle growth rate is consistent with the mechanism of recondensation, onto droplets which survive the pulse passage, of water vapor driven from the fog droplets, by absorption of pulse energy. For any aerosol whose particle size is significantly altered by laser pulse passage, the effect of the pulse on light extinction is determined by initial aerosol particle size and index of refraction as well as the wavelength of the light to be transmitted.

Fowler, M. C.

1983-10-01

252

Transmission of return-to-zero pulses in an optical split-step system based on reflecting fiber gratings  

NASA Astrophysics Data System (ADS)

A new variety of the "soliton management" in heterogeneous optical media is proposed. The system is composed as a periodic chain of nonlinear fibers with negligible intrinsic group-velocity dispersion (GVD), alternating with sections of unchirped fiber Bragg gratings (FBGs) operating in the reflection regime. Losses due to incomplete reflection are compensated by linear amplifiers. The model may apply to fiber-optic telecommunication links with periodically installed FBG modules, and it may be used for the design of laser setups. By means of extended simulations, we identify small regions in the underlying parameter space where this model, featuring the periodic separation of the Kerr nonlinearity and FBG-induced GVD (hence the name of the "split-step" system), supports stable transmission of RZ (return-to-zero) pulses, i.e., quasi-solitons. The effect of nonzero fiber's GVD on the stable transmission regime is considered too. Moderately unstable (partly usable) transmission regimes are found in larger regions of the parameter space; they may be of two different types, with the average nonlinearity either undercompensating or overcompensating the GVD. Interactions between the stable RZ pulses are also studied, leading to the identification of a minimum separation between them necessary for the suppression of interaction effects.

Tsaraf, Yoram; Malomed, Boris A.

2009-10-01

253

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

PubMed

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

Homma, Akira

2011-07-01

254

Characterization and realization of a 120kV, 200ns transmission line pulse generator  

Microsoft Academic Search

A 120kV \\/ 200ns \\/ 13J transmission line generator building is accurately studied. A design method for achieving compact and reliable Blumlein generators is elaborated and validated by three realizations. In order to estimate the transmission line transformer amplification and droop, a set of equations is established and a new simplified gain expression is suggested. Another set of equations to

M. Rivaletto; P. Pignolet

1998-01-01

255

High data rate pulse regeneration using non-linear transmission line technology (NLTL)  

Microsoft Academic Search

The application of Non-Linear Transmission Line (NLTL) technology to the restoration of signal integrity in electro-optic back-planes technology is reported. The non-linear transmission line synthesized uses coplanar wave-guide because it has better performance than the micro-strip line

M. Falah; D. Linton

2001-01-01

256

Optical fiber link for transmission of 1-nJ femtosecond laser pulses at 1550 nm.  

PubMed

We report on numerical and experimental characterization of the performance of a fiber link optimized for the delivery of sub-100-fs laser pulses at 1550 nm over several meters of fiber. We investigate the power handling capacity of the link, and demonstrate all-fiber delivery of 1-nJ pulses over a distance of 5.3 m. The fiber link consists of dispersion-compensating fiber (DCF) and standard single-mode fiber. The optical pulses at different positions in the fiber link are measured using frequency-resolved optical gating (FROG). The results are compared with numerical simulations of the pulse propagation based on the generalized nonlinear Schrödinger equation. The high input power capacity of the fiber link allows the splitting and distribution of femtosecond pulses to an array of fibers with applications in multi-channel fiber-coupled terahertz time-domain spectroscopy and imaging systems. We demonstrate THz pulse generation and detection using a distributed fiber link with 32 channels and 2.6 nJ input pulse energy. PMID:20389717

Eichhorn, Finn; Olsson, Rasmus Kjelsmark; Buron, Jonas C D; Grüner-Nielsen, Lars; Pedersen, Jens Engholm; Jepsen, Peter Uhd

2010-03-29

257

Improved CW Technique for Measurement of Ultrasonic Attenuation.  

National Technical Information Service (NTIS)

A technique is described for measuring ultrasonic attenuation by determining the inflectional points of ultrasonic standing wave resonances. Measurements on tantalum are reported. Results obtained by this technique agree with those obtained by the pulse e...

R. G. Leisure

1972-01-01

258

Quasi-transform-limited pulse transmission in dispersion managed soliton system  

Microsoft Academic Search

A Gaussian pulse with frequency chirping is transmitted in a dispersion management (DM) soliton system. The existence of an initial chirping makes the pulsewidth and amplitude fluctuate over distance around their initial values, and increases the energy enhancement factor. The quasi-transform-limited pulse generated with spectral windowing is also propagated in the DM soliton system. With proper energy enhancement, the quasi-transform-limited

Yang Jing Wen; Xiang Lin Yang

1999-01-01

259

Reflection and transmission of optical narrow-extent pulses by axially excited chiral sculptured thin films  

NASA Astrophysics Data System (ADS)

Chiral sculptured thin films (STFs) have unidirectionally periodic electromagnetic constitutive properties and therefore exhibit the circular Bragg phenomenon. The time-domain Maxwell equations are solved using finite difference calculus in order to establish the spatiotemporal anatomy of the action of axially excited, chiral STF slabs on optical narrow-extent pulses (NEPs) modulating circularly polarized carrier waves. A Lorentzian model was adopted for the permittivity dyadics of the chiral STFs. The time-domain manifestation of the circular Bragg phenomenon is focussed on. First, on examining the refraction of NEPs by a chiral STF half-space, a light pipe and the pulse bleeding phenomenon are shown to occur -when the handednesses of the carrier wave and the chiral STF coincide and the carrier wavelength is in the vicinity of the center-wavelength of the Bragg regime. Next, pulse bleeding inside a chiral STF slab is shown to be responsible for the long wakes of reflected pulses and low energy contents of transmitted pulses, when the incident wave spectrums significantly overlap with the Bragg regime and the carrier waves have the same handedness as the chiral STF slab. Thus, a chiral STF slab can drastically affect the shapes, amplitudes, and spectral components of femtosecond pulses.

Geddes, J. B., III; Lakhtakia, A.

2001-01-01

260

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

PubMed

At ultra-high magnetic field (? 7T), B1 and ?B0 non-uniformities cause undesired inhomogeneities in image signal and contrast. Tailored radiofrequency pulses exploiting parallel transmission have been shown to mitigate these phenomena. However, the design of large flip angle excitations, a prerequisite for many clinical applications, remains challenging due the non-linearity of the Bloch equation. In this work, we explore the potential of gradient ascent pulse engineering to design non-selective spin-echo refocusing pulses that simultaneously mitigate severe B1 and ?B0 non-uniformities. The originality of the method lays in the optimization of the rotation matrices themselves as opposed to magnetization states. Consequently, the commonly used linear class of large tip angle approximation can be eliminated from the optimization procedure. This approach, combined with optimal control, provides additional degrees of freedom by relaxing the phase constraint on the rotation axis, and allows the derivative of the performance criterion to be found analytically. The method was experimentally validated on an 8-channel transmit array at 7T, using a water phantom with B1 and ?B0 inhomogeneities similar to those encountered in the human brain. For the first time in MRI, the rotation matrix itself on every voxel was measured by using Quantum Process Tomography. The results are complemented with a series of spin-echo measurements comparing the proposed method against commonly used alternatives. Both experiments confirm very good performance, while simultaneously maintaining a low energy deposition and pulse duration compared to well-known adiabatic solutions. PMID:23454576

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

2013-05-01

261

Wideband high efficiency binary transmission grating in fused silica for femtosecond pulse compression  

Microsoft Academic Search

Diffraction characteristics of binary transmission grating in fused silica are analyzed through rigorous numerical calculations. A wideband high efficiency grating is presented, which provides a diffraction efficiency of 92%-94% over the wavelength range of 710-870 nm.

Peng Lv; Changhe Zhou; Jijun Feng

2009-01-01

262

GaAs nonlinear transmission lines for picosecond pulse generation and millimeter-wave sampling  

Microsoft Academic Search

The GaAs nonlinear transmission line (NLTL) is a monolithic millimeter-wave integrated circuit consisting of a high-impedance transmission line loaded by reverse-biased Schottky contacts. The engineering of functional monolithic NLTLs is considered. Through generation of shock waves on the NLTL, the authors have generated electrical step functions with approximately 5 V magnitude and less than 1.4 ps fall time. Diode sampling

Mark J. W. Rodwell; Masayuki Kamegawa; Ruai Yu; Michael Case; Eric Carman; K. S. Giboney

1991-01-01

263

Ultrasonic in-Process Inspection of Resistance Spot Welds.  

National Technical Information Service (NTIS)

In the continued evaluation of the in-process ultrasonic approach to the nondestructive inspection of resistance spot welds, ultrasonic through-transmission measurements were extended to several types of metals to establish signal sensitivity and behavior...

G. E. Burbank W. D. Taylor

1966-01-01

264

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

265

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

Microsoft Academic Search

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

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

2000-01-01

266

Pulse compression using non-linear transmission lines (NLTLs) based on Schottky quantum barrier varactor diodes  

Microsoft Academic Search

Improving the bandwidth of multilayer PCB line cards in a telecommunications system is reported in this paper. The signal distortion due to frequency dependent attenuation and dispersion is compensated by regenerating the high frequency components of digital pulses using shock wave generation within the NLTL. Operation of the NLTL using conventional Schottky diode technology and using Schottky quantum barrier varactor

F. Mohammed; D. Linton; J. Williamson

2003-01-01

267

Controlled ultrasonic tissue erosion  

NASA Astrophysics Data System (ADS)

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

Cain, Charles

2003-04-01

268

Network Time Domain Transmission Line Representation for Short-Pulse Radiation by Periodic Phased Arrays  

Microsoft Academic Search

We are in the process of performing an efiective wide-band analysis for characterizing the electrodynamic behavior of phased array antennas, inflnite periodic structures, frequency selective surfaces and related applications, with emphasis on gaining physical insight into the phenomenology of short-pulse radiation. The present contribution shows the current status of our network-oriented dyadic TD GF for a planar array of sequentially

F. Capolino; L. B. Felsen; A. Della Villa

269

Chaotic pulse transmission and spiral formation in a calcium oscillation model.  

PubMed

We study a two-dimensional reaction-diffusion equation for calcium oscillation with a pacemaker region. When the pacemaker entrains the whole system, circular waves are observed as a target pattern. However, if the pace of the pacemaker is too fast, the pulse propagation to the outer region sometimes fails in a chaotic manner. We find that spiral waves are spontaneously created at the interface between the pacemaker region and the outer region. PMID:18517676

Sakaguchi, H; Woafo, P

2008-04-01

270

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

271

GaAs nonlinear transmission lines for picosecond pulse generation and millimeter-wave sampling  

NASA Astrophysics Data System (ADS)

The GaAs nonlinear transmission line (NLTL) is a monolithic millimeter-wave integrated circuit consisting of a high-impedance transmission line loaded by reverse-biased Schottky contacts. The engineering of functional monolithic NLTLs is considered. Through generation of shock waves on the NLTL, the authors have generated electrical step functions with about 5 V magnitude and less than 1.4 psec fall time. Diode sampling bridges strobed by NLTL shock-wave generators have attained bandwidths approaching 300 GHz and have applications in instruments for millimeter-wave waveform and network measurements. Also discussed are the circuit design and diode design requirements for picosecond NLTL shock-wave generators and NLTL-driven sampling circuits.

Rodwell, Mark J. W.; Kamegawa, Masayuki; Yu, Ruai; Case, Michael; Carman, Eric

1991-07-01

272

Continuous wave ultrasonic Doppler tomography  

PubMed Central

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

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

2011-01-01

273

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

Microsoft Academic Search

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

Ming Li; Kathiravan Krishnamurthi; Robert G. Harrison

1998-01-01

274

Generation and propagation of subpicosecond pulses in a photoconductive GaAs switch integrated onto a gold\\/YBa2Cu3Ox coplanar transmission line structure  

Microsoft Academic Search

We present a new type of photoconductive GaAs switch, which can be integrated directly onto an already existing high-Tc circuit. Our test circuit consists of two coupled coplanar transmission lines made of gold on top of a YBa2Cu3Ox layer grown on a MgO substrate. When the photoconductive switch is irradiated with femtosecond laser pulses, subpicosecond (0.4 ps) electric pulses are

Britt H. Larsen; Thorsten Holst; Yueqiang Shen; Torsten Freltoft; Christian J. Osbahr; Rune H. Jacobsen; Smen R. Keiding

1997-01-01

275

Laser ultrasonics for bubbly flow detection  

Microsoft Academic Search

Laser ultrasonics was used to study flow of air bubbles in still water. An experimental system was developed utilizing a Nd:YAG laser to generate ultrasonic pulses in the MHz range and a He-Ne laser beam to detect echoes from the bubble-water interfaces. Several methods were applied to compare ultrasonic waveform parameters with air flow rates. The results show a correlation

Darja Horvat; Janez Možina; Iztok žun; Matjaž Perpar

1998-01-01

276

Temperature dependence of ultrasonic propagation speed and attenuation in excised canine liver tissue measured using transmitted and reflected pulses  

NASA Astrophysics Data System (ADS)

Previous reported data from our laboratory demonstrated the temperature dependence of propagation speed and attenuation of canine tissue in vitro at discrete temperatures ranging from 25 to 95 °C. However, concerns were raised regarding heating the same tissue specimen over the entire temperature range, a process that may introduce irreversible and, presumably, cumulative tissue degradation. In this paper propagation speed and attenuation vs temperature are measured using multiple groups of samples, each group heated to a different temperature. Sample thicknesses are measured directly using a technique that uses both transmitted and reflected ultrasound pulses. Results obtained using 3 and 5 MHz center frequencies demonstrate a propagation speed elevation of around 20 m/s in the 22-60 °C range, and a decrease of 15 m/s in the 60-90 °C range, in agreement with previous results where the same specimens were subjected to the entire temperature range. However, sound speed results reported here are slightly higher than those reported previously, probably due to more accurate measurements of sample thickness in the present experiments. Results also demonstrate that while the propagation speed varies with temperature, it is not a function of tissue coagulation. In contrast, the attenuation coefficient depends on both tissue coagulation effects and temperature elevation.

Techavipoo, U.; Varghese, T.; Chen, Q.; Stiles, T. A.; Zagzebski, J. A.; Frank, G. R.

2004-06-01

277

Ultrasonic velocity dispersion in bovine cortical bone: an experimental study.  

PubMed

Cortical bone quality is determinant in bone fragility and its ultrasonic evaluation has become possible in clinical practice. However, the interaction between a broadband ultrasonic pulse and this complex multiscale medium remains poorly understood. The frequency dependence of phase velocity, which may impact clinical measurements, has been sparsely investigated. Our objective is to evaluate the determinants of the frequency dependence of phase velocity in bovine femoral cortical bone samples using an in vitro ultrasonic transmission device. The apparent phase velocity varies quasilinearly on a 1 MHz restricted bandwidth around 4 MHz. After compensating for diffraction effects, significant differences in velocity dispersion are obtained according to the anatomical location. The microstructure of each sample is determined using an optical microscope, which allows assessing the dependence of dispersion on the type of bone microstructure. Mostly positive but also negative values of dispersion are measured. Negative dispersion is mainly obtained in samples constituted of mixed microstructure, which may be explained by phase cancellation effects due to the presence of different microstructures within the same sample. Dispersion is shown to be related to broadband ultrasonic attenuation values, especially in the radial direction. Results are compared with the local Kramers-Kronig relationships. PMID:19045671

Haïat, Guillaume; Sasso, Magali; Naili, Salah; Matsukawa, Mami

2008-09-01

278

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

279

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

280

Parabolic pulse propagation in mean-zero dispersion-managed transmission systems and mode-locked laser cavities  

NASA Astrophysics Data System (ADS)

Self-similarity is a ubiquitous concept in the physical sciences used to explain a wide range of spatial- or temporalstructures observed in a broad range of applications and natural phenomena. Indeed, they have been predicted or observed in the context of Raman scattering, spatial soliton fractals, propagation in the normal dispersion regime with strong nonlinearity, optical amplifiers, and mode-locked lasers. These self-similar structures are typically long-time transients formed by the interplay, often nonlinear, of the underlying dominant physical effects in the system. A theoretical model shows that in the context of the universal Ginzburg-Landau equation with rapidly-varying, mean-zero dispersion, stable and attracting self-similar pulses are formed with parabolic profiles: the zero-dispersion similariton. The zero-dispersion similariton is the final solution state of the system, not a long-time, intermediate asymptotic behavior. An averaging analysis shows the self-similarity to be governed by a nonlinear diffusion equation with a rapidly-varying, mean-zero diffusion coefficient. Indeed, the leadingorder behavior is shown to be governed by the porous media (nonlinear diffusion) equation whose solution is the well-known Barenblatt similarity solution which has a parabolic, self-similar profile. The alternating sign of the diffusion coefficient, which is driven by the dispersion fluctuations, is critical to supporting the zero-dispersion similariton which is, to leading-order, of the Barenblatt form. This is the first analytic model proposing a mechanism for generating physically realizable temporal parabolic pulses in the Ginzburg-Landau model. Although the results are of restricted analytic validity, the findings are suggestive of the underlying physical mechanism responsible for parabolic (self-similar) pulse formation in lightwave transmission and observed in mode-locked laser cavities.

Bale, Brandon G.; Kutz, J. Nathan

2009-05-01

281

Signal processing for smart ultrasonic sensors  

Microsoft Academic Search

As typical smart sensors, ultrasonic sensors evaluate the information impressed on the propagating ultrasonic signal by the quantities to be sensed. Besides the ultrasonic transmission, reception, and time-dependent amplification, elementary signal processing includes time measurement, time-window evaluation, and phase detection. Flow velocities can be measured with high resolution and independently of the speed of sound using the lambda-locked loop (LLL).

V. Magori

1989-01-01

282

Ultrasonic Thermometry in Oil Shale Retorts.  

National Technical Information Service (NTIS)

The method relies on the principles of ultrasonic reflectometry to locate and determine temperatures within zones of a slender-rod-sensing element installed in the in-situ retort bed. The measurement technique consists of sending an ultrasonic pulse down ...

J. J. Ronchetto

1981-01-01

283

Ultrasonic thermometry in oil shale retorts  

Microsoft Academic Search

The method relies on the principles of ultrasonic reflectometry to locate and determine temperatures within zones of a slender-rod-sensing element installed in the in-situ retort bed. The measurement technique consists of sending an ultrasonic pulse down an element containing n zones spaced along its length. The zone boundaries are defined by n + 1 discontinuities within the element. The time

Ronchetto

1981-01-01

284

Pulse  

MedlinePLUS

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

285

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

PubMed

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

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

2010-10-01

286

pulses  

Microsoft Academic Search

This paper reports on photoionisation loading based on ultrafast pulses of singly-ionised stron- tium ions in a linear Paul trap. We take advantage of an autoionising resonance of Sr neutral atoms to form Sr+ by two-photon absorption of femtosecond pulses at a wavelength of 431 nm. We compare this technique to electron-bombardment ionisation and observe several advantages of photoionisation. It

S. Removille; R. Dubessy; Q. Glorieux; S. Guibal; T. Coudreau; L. Guidoni; J.-P. Likforman

287

The manufacturing of ultrasonic gas flow meters  

Microsoft Academic Search

From their introduction, ultrasonic flow meters have received a rapid acceptance as being one of the favored measurement methods for high accuracy custody transfer applications in high-pressure gas transmission systems. There are many benefits when using ultrasonic technology; increased rangeability and capacity over conventional measurement technology with unparalleled accuracy are near the top of the list. But in many cases,

Jan G Drenthen; Geeuwke de Boer

2001-01-01

288

Improved Ultrasonic Nondestructive Testing of Pressure Vessels.  

National Technical Information Service (NTIS)

Progress in the development of a synthetic aperture focusing technique for ultrasonic pulse-echo flaw evaluation is described. The progress includes improvement in display techniques, initial results of a Spotlight-mode scanning technique, improvement in ...

J. R. Frederick M. Dixon C. V. Broek D. Papworth M. Elzinga

1979-01-01

289

Improved Ultrasonic Nondestructive Testing of Pressure Vessels.  

National Technical Information Service (NTIS)

Test results and methods development for a synthetic aperture focusing technique for ultrasonic pulse-echo flaw evaluation are described. Verification of the system's flaw-imaging capability is presented in the form of test results from several different ...

J. R. Frederick C. J. J. Vandenbroek R. C. Fairchild M. B. Elzinga

1978-01-01

290

High-temperature and broadband immersion ultrasonic probes  

Microsoft Academic Search

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

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

2006-01-01

291

3-D finite element simulation for ultrasonic propagation in tooth  

Microsoft Academic Search

ObjectivesUltrasonic testing of the tooth has been suggested as an alternative method of identifying dental pathology. Due to the complex geometry and low transmission efficiency of ultrasonic signals in tooth structures, it is difficult to establish one-to-one correspondence between ultrasonic behaviour and specific tooth pathologies both in vitro and in vivo. In order to facilitate ultrasonic diagnosis in dental applications,

Xiaoqing Sun; Erich A. Witzel; Hongxin Bian; Shaoying Kang

2008-01-01

292

Ultrasonic Cleaners.  

National Technical Information Service (NTIS)

The selection of an ultrasonic cleaner for use in Air Force dental facilities depends on several factors. Determining the primary use of the unit prior to purchase is important because different units may be better suited to different tasks. Traditionally...

B. A. Matis B. J. Smith J. M. Powell L. P. Crigger J. M. Young

1982-01-01

293

Delamination detection in composites by laser ultrasonics  

NASA Astrophysics Data System (ADS)

In this paper an application of Laser Ultrasonics (LU) is presented on laminate panels. The method exploits a high energy pulsed laser generating ultrasonic waves on the material where it impinges and laser Doppler Mach-Zehnder interferometer for measuring the ultrasonic waves propagating on the testing object. The laser-ultrasonic has been applied to a thin Carbon Fiber Reinforced Polymer (CFRP) test sample where two different depth delaminations have been created. It will be demonstrated that the measurement system is extremely sensitive to the propagation of the ultrasonic waves generated by the high energy pulsed laser source and to the multiple reflections caused by the delamination even when this latter is located in depth.

Martarelli, M.; Chiariotti, P.; Pezzola, M.; Castellini, P.

2014-05-01

294

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

295

Ultrasonic Tissue Characterization: Correlation Between Biochemical and Ultrasonic Indices of Myocardial Injury  

Microsoft Academic Search

This study was designed to test the hypothesis that pathological changes in myocardium due to infarction, which are known to alter structural and functional properties of tissue, might be reflected in the ultrasonic attenuation as well. Ultrasonic attenuation over the range 2 to 9.5 MHz was obtained by transmitting broadband pulses through freshly excised tissue. demonstrated that phase cancellation effects

J. G. Miller; D. E. Yuhas; J. W. Mimbs; S. B. Dierker; L. J. Busse; J. J. Laterra; A. N. Weiss; B. E. Sobel

1976-01-01

296

A single-channel 1.92 Tbit/s, 64 QAM coherent optical pulse transmission over 150 km using frequency-domain equalization.  

PubMed

We demonstrate a single-channel 1.92 Tbit/s, 64 QAM coherent optical pulse optical time-division multiplexing (OTDM) transmission by utilizing frequency-domain equalization (FDE). FDE makes it possible to compensate precisely for the waveform distortions caused by hardware imperfections thus greatly improving the error vector magnitude (EVM) of the demodulated 64 QAM signal compared with that obtained with a conventional FIR filter. As a result, a coherent 64 QAM OTDM transmission over 150 km with a bit error rate of below the forward error correction limit of 2 x 10?³ (requiring 7% overhead) was achieved for the first time. PMID:24104167

Otuya, David Odeke; Kasai, Keisuke; Yoshida, Masato; Hirooka, Toshihiko; Nakazawa, Masataka

2013-09-23

297

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

298

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, D. B.; Salem, J. A.; Generazio, E. R.

1990-01-01

299

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

300

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

301

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

302

Ultrasonic Thermometry  

Microsoft Academic Search

Ultrasonic thermometers are based on the temperature dependence of sound velocity. immersed in the medium. inert g ases, provide temperature measurements up to 20, 000K. second range. Using a momentary contact coupling technique, t he temperature inside steel up to 1500K has been measured. Thin wire sensors have been used in nuclear and industrial applications where conditions preclude the use

L. C. Lynnworth; E. P. Papadakis

1970-01-01

303

In Situ Ultrasonic Monitoring of Aluminum Ion Hydrolysis in Aqueous Solutions: Instrumentation, Techniques, and Comparisons to pH-Metry  

Microsoft Academic Search

A cross-disciplinary experimental study related to both ultrasonic instrumentation and analytical chemistry is reported. The hydrolysis process was conducted by time-resolved titration in a fully automated manner. Acquired ultrasonic records were processed in order to estimate the propagation delay of the ultrasonic pulse in the evolving medium. The limited hardware resolution of two different ultrasonic instruments employed was improved by

Alexander N. Kalashnikov; Kirill L. Shafran; Vladimir G. Ivchenko; Richard E. Challis; Carole C. Perry

2007-01-01

304

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

305

Simultaneous measurement of liquid velocity and interface profiles of horizontal duct wavy flow by ultrasonic velocity profile meter  

Microsoft Academic Search

A simultaneous measurement of the liquid velocity and interface profiles was performed for stratified-smooth and wavy flows in a horizontal duct using a ultrasonic velocity profile (UVP) meter. The influences of the reflections of ultrasonic pulses at the gas–liquid interface and channel bottom were reduced by using an absorbent for the ultrasonic pulses on the duct bottom wall and optimization

Hideo Nakamura; Masaya Kondo; Yutaka Kukita

1998-01-01

306

Improved real-time volumetric ultrasonic imaging system  

NASA Astrophysics Data System (ADS)

A real-time volumetric ultrasonic imaging system has been improved through the use of parallel processing in two dimensions. The imaging system uses pulse-echo phased array principles to steer a two-dimensional transducer array in a pyramidal scan format. The transducer array consists of 96 transmit elements and 32 receive elements, and operates at a center frequency of 2.5 Mhz. Parallel processing allows reception of 16 unique view directions distributed over a small pyramidal volume during receive. Information from the 16 directions is obtained simultaneously after the transmission of an ultrasonic pulse. Images consisting of 4096 lines are produced at a rate of over 15 frames/second. The images are analogous to those produced by an optical camera or the human eye and supply more information than conventional sonograms. Echo data for the scanned volume is presented as projection images with depth perspective, stereoscopic pairs, multiple tomographic images, or C-scans. Potential medical applications include improved anatomic visualization, tumor localization, and better assessment of cardiac function.

Pavy, Henry G.; Smith, Stephen W.; von Ramm, Olaf T.

1991-07-01

307

Ultrasonic thermometry in oil shale retorts  

SciTech Connect

The method relies on the principles of ultrasonic reflectometry to locate and determine temperatures within zones of a slender-rod-sensing element installed in the in-situ retort bed. The measurement technique consists of sending an ultrasonic pulse down an element containing n zones spaced along its length. The zone boundaries are defined by n + 1 discontinuities within the element. The time intervals between pairs of returning echoes, caused by reflections from these discontinuities, are measured electronically. These measured time intervals are then related to the average temperature of the corresponding zones. Preliminary results are encouraging, and it appears that the ultrasonic thermometer can be a useful in situ instrument.

Ronchetto, J.J.

1981-05-06

308

Pulse transformers  

Microsoft Academic Search

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

H. Lord

1971-01-01

309

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

310

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

311

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

312

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

313

Ultrasonic Frequency Difference Generation to Characterize Fluids in Saturated Berea Sandstone.  

SciTech Connect

The use of nonlinear acoustics to characterize fluids in porous media is presented. The acoustic nonlinearity in sandstone is affected by the presence of water or oil. This difference in properties that affect the sound propagation through such media can be used to determine whether a piece of sandstone contains water or oil. Traditional methods of characterizing porous media usually rely on the transmission or reflection of a single ultrasonic probe pulse. The technique presented in this paper uses a method of generating a probe pulse inside the porous medium from the interaction of two pulses. Information about the medium is then contained in the propagation of this probe signal back to a receiver. The main advantage of this approach is that it allows implementation of this technique inside a borehole for characterizing the porous media outside.

Keatkowski, C. S. (MST-11); Sinha, D. N. (Dipen N)

2001-01-01

314

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

315

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

316

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

317

Ultrasonic Attenuation Measurement by Spectral Ratios Utilizing Signal Processing Techniques  

Microsoft Academic Search

A new approach using signal averaging and signal processing is described for measuring ultrasonic attenuation of compressional (P) and shear (S) waves in highly attenuative (low Q) materials. Broadband ultrasonic pulses in the frequency range of 0.7-1.1 MHz are transmitted through a specimen to be characterized for comparison to a reference with low dissipation. Attenuation is calculated from the ratio

Frederick M. Sears; Brian P. Bonner

1981-01-01

318

NOTE: Ultrasonic device for the noninvasive diagnosis of compartment syndrome  

Microsoft Academic Search

An ultrasonic device for the diagnosis of acute compartment syndrome is described and results on six human cadaveric legs are presented. The ultrasonic device uses a pulsed phase locked loop (PPLL) to measure sub-micrometer displacements of the fascia wall. These displacements occur as a result of volume expansion of the muscle compartment of the lower leg and are related to

John E. Lynch; Joseph S. Heyman; Alan R. Hargens

2004-01-01

319

Ultrasonic device for the noninvasive diagnosis of compartment syndrome  

Microsoft Academic Search

An ultrasonic device for the diagnosis of acute compartment syndrome is described and results on six human cadaveric legs are presented. The ultrasonic device uses a pulsed phase locked loop (PPLL) to measure sub-micrometer displacements of the fascia wall. These displacements occur as a result of volume expansion of the muscle compartment of the lower leg and are related to

John E Lynch; Joseph S Heyman; Alan R Hargens

2004-01-01

320

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.

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

2013-01-01

321

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

322

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

323

Measurement of Broadband Temperature-Dependent Ultrasonic Attenuation and Dispersion Using Photoacoustics  

Microsoft Academic Search

The broadband ultrasonic characterization of biological fluids and tissues is important for the continued development and application of high-resolution ultrasound imaging modalities. Here, a photoacoustic technique for the transmission measurement of temperature-dependent ultrasonic attenuation and dispersion is described. The system uses a photoacoustic plane wave source constructed from a polymethylmethacrylate substrate with a thin optically absorbent layer. Broadband ultrasonic waves

Bradley E. Treeby; Benjamin Cox; Edward Zhang; Sarah Patch; Paul Beard

2009-01-01

324

Process Monitoring of Cast Explosive Solidification Molding by on-line Multichannel Ultrasonic Measurement  

Microsoft Academic Search

The process of cast explosive solidification molding h as been dynamic monitored by multi-channel ultrasonic transmission method. It present s the regular pattern of ultrasonic attenuation, velocity and waveform in this process. The results show that velocity values and waveform are relative to solidification speed and physica l characterization on the phase border, and ultrasonic attenuation is relative to the

Weibin ZHANG; Yong TIAN; Hongping ZHOU; Zhanfeng YANG; Guan LUO Hehou ZONG

325

Ultrasonic attenuation of biomaterials for compensation in photoacoustic imaging  

Microsoft Academic Search

Ultrasonic attenuation in biomaterials limits the quality and resolution of ultrasonic imaging. This work presents a simple and reliable method to investigate acoustic attenuation of biological tissue samples and liquids in order to improve reconstruction algorithms for photoacoustic imaging. For this purpose broadband high-frequency single transmission measurements were performed. The spectra of the acquired signals were compared to reference measurements

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

2011-01-01

326

Uses of Ultrasonics in Radio, Radar and Sonar Systems  

Microsoft Academic Search

A short historical review is given of the development of ultrasonics. Uses in the low-amplitude range are sonar systems, dispersive and nondispersive delay lines, ultrasonic inspectoscopes, and crystal and mechanical filters. In all of these applications, the very low internal friction of metals and fused silica provides very low losses, while the guided wave properties of various shaped transmission paths

Warren Mason

1962-01-01

327

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

328

Ultrasonic properties of granular media saturated with dnapl/watermixtures  

SciTech Connect

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

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

2007-09-15

329

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

330

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

331

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

332

A Multiconductor Model for Determining the Response of Power Transmission and Distribution Lines to a High Altitude Electromagnetic Pulse (HEMP)  

Microsoft Academic Search

A nuclear detonation at an altitude above 40 km above the earth's surface would produce an intense transient electromagnetic field, known as a high altitude electromagnetic pulse (HEMP). These electromagnetic fields radiated from the blast vary with the detonation location and weapon characteristics. At detonation altitudes ranging from 100 km to 500 km, large portions of electrical power system interconnections

F. M. Tesche; P. R. Barnes

1989-01-01

333

The HEMP (High-altitude Electromagnetic Pulse) response of a long transmission line buried in the earth  

Microsoft Academic Search

This paper documents the calculation of the current coupled to a long, buried, insulated cable excited by a horizontally polarized plane-wave electromagnetic pulse (EMP) field. This result is compared to the current measured on a similar long, buried cable located approximately 800 ft from a radiating, horizontally polarized EMP simulator having the same driving horizontal field. Originator-assigned key words include:

R. P. Manriquez; R. J. Reyzer; J. F. Sweton

1984-01-01

334

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

335

On variant strategies to solve the magnitude least squares optimization problem in parallel transmission pulse design and under strict SAR and power constraints.  

PubMed

Parallel transmission is a very promising candidate technology to mitigate the inevitable radio-frequency (RF) field inhomogeneity in magnetic resonance imaging at ultra-high field. For the first few years, pulse design utilizing this technique was expressed as a least squares problem with crude power regularizations aimed at controlling the specific absorption rate (SAR), hence the patient safety. This approach being suboptimal for many applications sensitive mostly to the magnitude of the spin excitation, and not its phase, the magnitude least squares (MLS) problem then was first formulated in 2007. Despite its importance and the availability of other powerful numerical optimization methods, the MLS problem yet has been faced almost exclusively by the pulse designer with the so-called variable exchange method. In this paper, we investigate various two-stage strategies consisting of different initializations and nonlinear programming approaches, and incorporate directly the strict SAR and hardware constraints. Several schemes such as sequential quadratic programming, interior point methods, semidefinite programming and magnitude squared least squares relaxations are studied both in the small and large tip angle regimes with RF and static field maps obtained in vivo on a human brain at 7T. Convergence and robustness of the different approaches are analyzed, and recommendations to tackle this specific problem are finally given. Small tip angle and inversion pulses are returned in a few seconds and in under a minute respectively while respecting the constraints, allowing the use of the proposed approach in routine. PMID:24595346

Hoyos-Idrobo, A; Weiss, P; Massire, A; Amadon, A; Boulant, N

2014-03-01

336

Increasing average power in medical ultrasonic endoscope imaging system by coded excitation  

NASA Astrophysics Data System (ADS)

Medical ultrasonic endoscope is the combination of electronic endoscope and ultrasonic sensor technology. Ultrasonic endoscope sends the ultrasonic probe into coelom through biopsy channel of electronic endoscope and rotates it by a micro pre-motor, which requires that the length of ultrasonic probe is no more than 14mm and the diameter is no more than 2.2mm. As a result, the ultrasonic excitation power is very low and it is difficult to obtain a sharp image. In order to increase the energy and SNR of ultrasonic signal, we introduce coded excitation into the ultrasonic imaging system, which is widely used in radar system. Coded excitation uses a long coded pulse to drive ultrasonic transducer, which can increase the average transmitting power accordingly. In this paper, in order to avoid the overlapping between adjacent echo, we used a four-figure Barker code to drive the ultrasonic transducer, which is modulated at the operating frequency of transducer to improve the emission efficiency. The implementation of coded excitation is closely associated with the transient operating characteristic of ultrasonic transducer. In this paper, the transient operating characteristic of ultrasonic transducer excited by a shock pulse ?(t) is firstly analyzed, and then the exciting pulse generated by special ultrasonic transmitting circuit composing of MD1211 and TC6320. In the final part of the paper, we designed an experiment to validate the coded excitation with transducer operating at 5MHz and a glass filled with ultrasonic coupling liquid as the object. Driven by a FPGA, the ultrasonic transmitting circuit output a four-figure Barker excitation pulse modulated at 5MHz, +/-20 voltage and is consistent with the transient operating characteristic of ultrasonic transducer after matched by matching circuit. The reflected echo from glass possesses coded character, which is identical with the simulating result by Matlab. Furthermore, the signal's amplitude is higher.

Chen, Xiaodong; Zhou, Hao; Wen, Shijie; Yu, Daoyin

2008-12-01

337

High resolution ultrasonic densitometer  

NASA Astrophysics Data System (ADS)

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 indiction, 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.

1983-11-01

338

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

339

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

340

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

341

The HEMP (High-altitude Electromagnetic Pulse) response of a long transmission line buried in the earth  

NASA Astrophysics Data System (ADS)

This paper documents the calculation of the current coupled to a long, buried, insulated cable excited by a horizontally polarized plane-wave electromagnetic pulse (EMP) field. This result is compared to the current measured on a similar long, buried cable located approximately 800 ft from a radiating, horizontally polarized EMP simulator having the same driving horizontal field. Originator-assigned key words include: Transmitted E field below ground, Conductivity, Dielectric constant, Distributed source, and Matrix tridiagonalization.

Manriquez, R. P.; Reyzer, R. J.; Sweton, J. F.

1984-09-01

342

Coherent, wavelength-tunable ultrasonic acoustic modes stimulated in optical fiber, microcapillaries, and planar microfluidic networks using crossed-picosecond laser pulses  

NASA Astrophysics Data System (ADS)

This article describes the use of optical methods based on picosecond transient gratings to stimulate and detect ultrasonic acoustic modes in several important structures with dimensions less than ~200 ?m: single-mode optical fiber, cylindrical microcapillary tubes, and planar microfluidic networks. The measurements illuminate the characteristics and dispersion of acoustic modes-Rayleigh and Lamb-like modes and Scholte-Stoneley waves-in three-dimensional microsystems with feature sizes that are comparable to the modal wavelengths. The results demonstrate, for example, the ability to measure, rapidly and nondestructively, the mechanical characteristics of on-fiber metal and polymer coatings. They also illustrate real-time monitoring of the elastic and loss moduli, and thermal diffusivities of nanoliter volumes of material contained in planar microfluidic channels during the course of photochemical curing reactions. The techniques are potentially useful for applications ranging from characterization of high-frequency acoustic modes in optical fiber that may be relevant to new types of in-fiber acousto-optic filters and modulators, to detection in microfluidic total analysis systems.

Rogers, John A.

1999-09-01

343

Development of AN Ultrasonic Liquid Steel Inclusion Monitor  

NASA Astrophysics Data System (ADS)

The application of ultrasonic scattering methodologies to measure inclusions in metals in the liquid state could enable the development of techniques for understanding non-metallic particulate inclusion content or cleanliness at different process areas. The MV20/20 ultrasonic system developed for the aluminum industry has achieved some success. However, the operational temperatures evident in steel production suggest many practical issues in designing an ultrasonic measurement system due to the inability to propagate an ultrasonic pulse directly into liquid steel. This paper describes the latest developments of a novel disposable ultrasonic probe that overcomes pulse introduction difficulties as well as some of the associated issues evident in liquid steel application. A trial at the Corus pilot plant facility in the U.K shows that probe design can be used to detect backwall signals at a distance of 20 cm with a signal to noise ratio in the region of 10 dB.

Currie, A. C.; Millman, S. M.; Johnstone, S.

2010-02-01

344

In plant demonstration of high temperature EM pulser and pulsed EMAT receiver: Final report: Experimental development and testing of ultrasonic system for high temperature applications on hot steel  

SciTech Connect

This report describes work performed under the Field Work Proposal on the ''In-Plant Demonstration of a High-Temperature EM Pulser and pulsed EMAT Receiver'' for the Department of Energy's Office of Industrial Programs. Cost sharing by the American Iron and Steel Institute (AISI) helped provide both technical guidance and equipment for the plant demonstration. This report covers the time period from January 1988 through September 1988.

Boyd, D.M.; Sperline, P.D.

1988-11-01

345

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.

2012-01-01

346

Fiber transmission and generation of ultrawideband pulses by direct current modulation of semiconductor lasers and chirp-to-intensity conversion.  

PubMed

Optical pulses generated by current modulation of semiconductor lasers are strongly frequency chirped. This effect has been considered pernicious for optical communications. We take advantage of this effect for the generation of ultrawideband microwave signals by using an optical filter to achieve chirp-to-intensity conversion. We also experimentally achieve propagation through a 20 km nonzero dispersion shifted fiber with no degradation of the signal at the receiver. Our method constitutes a prospective low-cost solution and offers integration capabilities with fiber-to-the-customer-premise systems. PMID:18246135

Torres-Company, Víctor; Prince, Kamau; Monroy, Idelfonso Tafur

2008-02-01

347

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

348

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

349

High resolution Bragg edge transmission spectroscopy at pulsed neutron sources: Proof of principle experiments with a neutron counting MCP detector  

NASA Astrophysics Data System (ADS)

The high spatial and temporal resolution of a neutron counting detector using microchannel plates (MCPs) combined with Medipix2/Timepix readout can substantially improve the spatial resolution of neutron transmission spectroscopy, as shown in our proof-of-principle experiments. Provided that the neutron fluence and data acquisition time are sufficient, transmission spectra can be acquired in each 55×55 ?m2 pixel of the detector, allowing high spatial resolution mapping of Bragg edge positions. Our first experiment demonstrates that energy resolution as high as ?E/E<1% or ?E<4 mÅ can be achieved. Variation of the residual strain in a well-characterized VAMAS round robin shrink-fitted Al ring-and-plug sample was measured with ˜200 microstrain resolution through an accurate mapping of the first (1 1 1) Bragg edge. The measured stress profile agrees well with the expected values for that particular sample. More developments on the detector processing electronics are required in order to reduce the data acquisition times by enabling simultaneous measurements of spectra in a wide energy range covering multiple Bragg edges.

Tremsin, A. S.; McPhate, J. B.; Kockelmann, W.; Vallerga, J. V.; Siegmund, O. H. W.; Feller, W. B.

2011-05-01

350

Ultrasonic Flowmeter for Gases.  

National Technical Information Service (NTIS)

An ultrasonic flowmeter is developed for use in natural gas mains. The characteristics of the application and the dynamic head device presently employed are described. The performance requirements, design, and prototype testing of the ultrasonic instrumen...

D. A. Bender L. R. Glicksman C. R. Peterson

1984-01-01

351

Ultrasonic Convection Cooling.  

National Technical Information Service (NTIS)

The report discusses an investigation of ultrasonic cooling techniques. Natural and forced convective cooling parameters were measured, with and without the application of ultrasonic agitation. It was experimentally determined that application of the tech...

J. E. McCormick T. W. Walsh

1964-01-01

352

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

353

Ultrasonic Determination Of Recrystallization  

NASA Technical Reports Server (NTRS)

State of recrystallization identified. Measurement of ultrasonic attenuation shows promise as means of detecting recrystallization in metal. Technique applicable to real-time acoustic monitoring of thermomechanical treatments. Starting with work-hardened material, one ultrasonically determines effect of annealing, using correlation between ultrasonic attenuation and temperature.

Generazio, Edward R.

1988-01-01

354

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

355

Ultrasonic Ranging System With Increased Resolution  

NASA Technical Reports Server (NTRS)

Master-oscillator frequency increased. Ultrasonic range-measuring system with 0.1-in. resolution provides continuous digital display of four distance readings, each updated four times per second. Four rangefinder modules in system are modified versions of rangefinder used for automatic focusing in commercial series of cameras. Ultrasonic pulses emitted by system innocuous to both people and equipment. Provides economical solutions to such distance-measurement problems as posed by boats approaching docks, truck backing toward loading platform, runway-clearance readout for tail of airplane with high angle attack, or burglar alarm.

Meyer, William E.; Johnson, William G.

1987-01-01

356

Measurement of broadband temperature-dependent ultrasonic attenuation and dispersion using photoacoustics.  

PubMed

The broadband ultrasonic characterization of biological fluids and tissues is important for the continued development and application of high-resolution ultrasound imaging modalities. Here, a photoacoustic technique for the transmission measurement of temperature-dependent ultrasonic attenuation and dispersion is described. The system uses a photoacoustic plane wave source constructed from a polymethylmethacrylate substrate with a thin optically absorbent layer. Broadband ultrasonic waves are generated by illuminating the absorbent layer with nanosecond pulses of laser light. The transmitted ultrasound waves are detected by a planar 7-microm high-finesse Fabry-Perot interferometer. Temperature-induced thickness changes in the Fabry-Perot interferometer are tracked to monitor the sample temperature and maintain the sensor sensitivity. The measured -6 dB bandwidth for the combined source and sensor is 1 to 35 MHz, with an attenuation corrected signal level at 100 MHz of -10 dB. The system is demonstrated through temperature-dependent ultrasound measurements in castor oil and olive oil. Power law attenuation parameters are extracted by fitting the experimental attenuation data to a frequency power law while simultaneously fitting the dispersion data to the corresponding Kramers-Krönig relation. The extracted parameters are compared with other calibration measurements previously reported in the literature. PMID:19686982

Treeby, Bradley E; Cox, Benjamin T; Zhang, Edward Z; Patch, Sarah K; Beard, Paul C

2009-08-01

357

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

358

Energetic cost of sexual attractiveness: ultrasonic advertisement in wax moths  

Microsoft Academic Search

Pair formation in the lesser wax moth,Achroia grisella(Lepidoptera: Pyralidae), is initiated by male ultrasonic signals that attract receptive females. Individual males vary in attractiveness to females, and the most attractive males are distinguished by exaggeration of three signal characters: pulse rate, peak amplitude and asynchrony interval (temporal separation between pulses generated by movements of the left and right wings during

KLAUS REINHOLD; MICHAEL D. GREENFIELD; YIKWEON JANG; ALBERTO BROCE

1998-01-01

359

Characterization of defects in plates by two-dimensional ultrasonic displacement maps: comparison between pulsed TV-holography measurements and finite element method predictions  

NASA Astrophysics Data System (ADS)

Pulsed TV-holography (PTVH) can be used for obtaining two-dimensional maps of instantaneous out-of-plane displacements in plates. In particular, scattering patterns generated by the interaction of elastic waves with defects can be measured with PTVH and employed for non-destructive inspection and damage detection in plate structures. For quantitative characterization of damage (position, dimensions, orientation, etc.) on this basis, modeling of elastic wave scattering is usually performed in terms of full-vector three-dimensional formulations based on elasticity theory. In this work, a finite element method (FEM) applied to a two-dimensional scalar model based on Helmholtz equation is employed for obtaining a quantitative description of the scattering patterns, avoiding the aforementioned more complex and rigorous standard approach. Simulated scattering patterns are obtained with the scalar FEM assuming harmonic regime and free-stress boundary conditions. The corresponding experimental interaction of narrowband Rayleigh-Lamb waves with artificial defects in plates are measured using our specifically developed PTVH system. In our case, the raw optical phase-difference values are processed by employing a specially developed procedure, based on a two step spatial Fourier transform method, to derive a high quality two-dimensional acoustic field map from which an important part of the noise component has been filtered out. A comparison between filtered experimental maps and FEM simulated maps is developed, considering defects with different sizes in relation to the acoustic wavelength.

Rodríguez-Gómez, P.; López-Vázquez, J. Carlos; Trillo, Cristina; Doval, Ángel F.; Fernández, José L.

2010-09-01

360

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

361

Ultrasonic monitoring of pitting corrosion  

NASA Astrophysics Data System (ADS)

Exposure to corrosive substances in high temperature environments can cause damage accumulation in structural steels, particularly in the chemical and petrochemical industries. The interaction mechanisms are complex and varied; however initial damage propagation often manifests itself in the form of localized areas of increased material loss. Recent development of an ultrasonic wall thickness monitoring sensor capable of withstanding temperatures in excess of 500°C has allowed permanent monitoring within such hostile environments, providing information on how the shape of a pulse which has reflected from a corroding surface can change over time. Reconstructing localized corrosion depth and position may be possible by tracking such changes in reflected pulse shape, providing extra information on the state of the backwall and whether process conditions should be altered to increase plant life. This paper aims to experimentally investigate the effect certain localized features have on reflected pulse shape by `growing' artificial defects into the backwall while wall thickness is monitored using the sensor. The size and complexity of the three dimensional scattering problem lead to the development of a semi-analytical simulation based on the distributed point source method (DPSM) which is capable of simulating pulse reflection from complex surfaces measuring approximately 17×10? Comparison to experimental results show that amplitude changes are predicted to within approximately 1dB and that pulse shape changes are accurately modelled. All experiments were carried out at room temperature, measurements at high temperature will be studied in the future.

Jarvis, A. J. C.; Cegla, F. B.; Bazaz, H.; Lozev, M.

2013-01-01

362

A novel ultrasonic array incorporating composite transducer technology  

Microsoft Academic Search

A new type of ultrasonic array transducer that incorporates the high bandwidth reception properties of PVDF with the greater transmission sensitivity of a composite transducer is presented. Through careful choice of epoxy phase for the composite polymer matrix and a novel electroding technique, the composite maintains its normal transmission sensitivity but with the added advantage of practical flexibility. The authors

D. J. Powell; G. Hayward

1992-01-01

363

Laser generation and reception of acoustic ultrasonic waves in solids  

NASA Astrophysics Data System (ADS)

Pulses of longitudinal, shear and surface waves are generated when a powerful laser pulse interacts with a surface of a solid. These waves serve to control strength, structure, and dynamic modulus of elasticity of solids. They are also used for ultrasonic testing.The optical methods and means have been developed in Dalstandart, RSRI of PTM, for generation and reception of ultrasonic waves in the frequency range of 0-30 MHz. Efficient techniques have been devised to determine different parameters of ultrasonic wave propagation, such as propagation velocities, coefficients of sound attenuation, and acoustic dispersion. Based on theoretical and experimental background the devised installations offer the highest accuracy for measurement of parameters of ultrasonic wave propagation in solids.

Arkhipov, V. I.; Bazylev, P. V.; Lugovoy, V. A.

2007-03-01

364

Ultrasonic Nondestructive Characterization of Adhesive Bonds  

NASA Technical Reports Server (NTRS)

Adhesives and adhesive joints are widely used in various industrial applications to reduce weight and costs, and to increase reliability. For example, advances in aerospace technology have been made possible, in part, through the use of lightweight materials and weight-saving structural designs. Joints, in particular, have been and continue to be areas in which weight can be trimmed from an airframe through the use of novel attachment techniques. In order to save weight over traditional riveted designs, to avoid the introduction of stress concentrations associated with rivet holes, and to take full advantage of advanced composite materials, engineers and designers have been specifying an ever-increasing number of adhesively bonded joints for use on airframes. Nondestructive characterization for quality control and remaining life prediction has been a key enabling technology for the effective use of adhesive joints. Conventional linear ultrasonic techniques generally can only detect flaws (delamination, cracks, voids, etc) in the joint assembly. However, more important to structural reliability is the bond strength. Although strength, in principle, cannot be measured nondestructively, a slight change in material nonlinearity may indicate the onset of failure. Furthermore, microstructural variations due to aging or under-curing may also cause changes in the third order elastic constants, which are related to the ultrasonic nonlinear parameter of the polymer adhesive. It is therefore reasonable to anticipate a correlation between changes in the ultrasonic nonlinear acoustic parameter and the remaining bond strength. It has been observed that higher harmonics of the fundamental frequency are generated when an ultrasonic wave passes through a nonlinear material. It seems that such nonlinearity can be effectively used to characterize bond strength. Several theories have been developed to model this nonlinear effect. Based on a microscopic description of the nonlinear interface binding force, a quantitative method was presented. Recently, a comparison between the experimental and simulated results based on a similar theoretical model was presented. A through-transmission setup for water immersion mode-converted shear waves was used to analyze the ultrasonic nonlinear parameter of an adhesive bond. In addition, ultrasonic guided waves have been used to analyze adhesive or diffusion bonded joints. In this paper, the ultrasonic nonlinear parameter is used to characterize the curing state of a polymer/aluminum adhesive joint. Ultrasonic through-transmission tests were conducted on samples cured under various conditions. The magnitude of the second order harmonic was measured and the corresponding ultrasonic nonlinear parameter was evaluated. A fairly good correlation between the curing condition and the nonlinear parameter is observed. The results show that the nonlinear parameter might be used as a good indicator of the cure state for adhesive joints.

Qu, Jianmin

1999-01-01

365

Ultrasonic sensors in air  

Microsoft Academic Search

Ultrasonic sensors in air are intelligent sensors, which use wave-propagation phenomena in air to measure physical or chemical variables. With accordance to the influence principle, two main types of ultrasonic sensors can be differentiated. Propagation-path sensors decode changes on propagation to obtain a fast measurement of temperature, pressure variations or gas concentration. Most important are ultrasonic flow sensor e.g. for

Valentin Magori

1994-01-01

366

Wedges for ultrasonic inspection  

DOEpatents

An ultrasonic transducer device is provided which is used in ultrasonic inspection of the material surrounding a threaded hole and which comprises a wedge of plastic or the like including a curved threaded surface adapted to be screwed into the threaded hole and a generally planar surface on which a conventional ultrasonic transducer is mounted. The plastic wedge can be rotated within the threaded hole to inspect for flaws in the material surrounding the threaded hole.

Gavin, Donald A. (Rexford, NY)

1982-01-01

367

Ultrasonic Bolt Gage  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

368

Compound Quantitative Ultrasonic Tomography of Long Bones Using Wavelets Analysis  

NASA Astrophysics Data System (ADS)

Compound Quantitative Ultrasonic Tomography (CQUT)is used to long bones imaging. We showed that an iterative tool might be used to provide, from reflection tomography, qualitative images of the shape of the object, and to provide, from transmission tomography, quantitative images of the velocity map. Both tomographies are based on ultrasonic propagation in bones, particularly perturbed by this high-contrasted heterogeneous medium. Reflected and transmitted signal are composed of several packages of waves. We propose a novel algorithm based on the wavelet analysis tool adapted to ultrasonic signals that allow the transmitted signals to be cleaned and filtered and the useful information to be separated from the unwanted noise

Lasaygues, P.

369

Ultrasonic attenuation measurements determine onset, degree, and completion 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 volume 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.

1988-01-01

370

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) [Schenectady, NY

1985-01-01

371

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

372

Precise-micro PECM System and Its Applications Combining Synchronizing Ultrasonical Vibration  

Microsoft Academic Search

The precise-micro PECM (Pulse Electrochemical Machining) combining synchronous ultrasonic vibration is proposed as a new technology for to solve the difficulty machining problems of conductive hard and tough materials. The feasibility of micro-PECM combining synchronous ultrasonic vibration is studied. The synchronous way is analyzed; the synchronous electrical circuit is designed and made. The synchronous electrochemical micro-machining system combining ultrasonical vibration

Zhu Yongwei; Jia Lianjie; Diao Guohu; Miao Xinglei; Zhang Chaofeng

2011-01-01

373

Ultrasonic convective cooling  

Microsoft Academic Search

This paper discusses an in-the-house research investigation of ultrasonic cooling techniques. Natural and forced convective cooling parameters were measured, with and without the application of ultrasonic agitation. It was experimentally determined that application of the technique resulted in as much as a three fold improvement in heat transfer. Comparisons of the effectiveness of the various modes of agitation were drawn.

J. McCormick; T. Walsh

1964-01-01

374

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

375

Ultrasonic Gas Separator.  

National Technical Information Service (NTIS)

Gas bubbles in a moving fluid are collected in a chamber alongside the conduit carrying the fluid. In a preferred embodiment, an ultrasonic transducer cooperates with a reflector to create a standing ultrasonic wave pattern that is oriented at an acute an...

R. B. Philips R. Kuklinski

1994-01-01

376

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

377

Evaluation of adaptation to visually induced motion sickness based on the maximum cross-correlation between pulse transmission time and heart rate  

PubMed Central

Background Computer graphics and virtual reality techniques are useful to develop automatic and effective rehabilitation systems. However, a kind of virtual environment including unstable visual images presented to wide field screen or a head mounted display tends to induce motion sickness. The motion sickness induced in using a rehabilitation system not only inhibits effective training but also may harm patients' health. There are few studies that have objectively evaluated the effects of the repetitive exposures to these stimuli on humans. The purpose of this study is to investigate the adaptation to visually induced motion sickness by physiological data. Methods An experiment was carried out in which the same video image was presented to human subjects three times. We evaluated changes of the intensity of motion sickness they suffered from by a subjective score and the physiological index ?max, which is defined as the maximum cross-correlation coefficient between heart rate and pulse wave transmission time and is considered to reflect the autonomic nervous activity. Results The results showed adaptation to visually-induced motion sickness by the repetitive presentation of the same image both in the subjective and the objective indices. However, there were some subjects whose intensity of sickness increased. Thus, it was possible to know the part in the video image which related to motion sickness by analyzing changes in ?max with time. Conclusion The physiological index, ?max, will be a good index for assessing the adaptation process to visually induced motion sickness and may be useful in checking the safety of rehabilitation systems with new image technologies.

Sugita, Norihiro; Yoshizawa, Makoto; Abe, Makoto; Tanaka, Akira; Watanabe, Takashi; Chiba, Shigeru; Yambe, Tomoyuki; Nitta, Shin-ichi

2007-01-01

378

Evaluation of Stress Using Ultrasonic Technique Based on Hilbert-Huang Transform  

Microsoft Academic Search

Pressures vessel are widely used in the modern industry. It is important to measure pressure of vessels. It has been proved that the change of ultrasonic velocity can be used to detect the stress of the material, and the velocity change can be obtained by estimating the time delay of two ultrasonic pulses. In this paper, the Rayleigh wave is

Q He; H J Zhang; H L Zhou

2006-01-01

379

Capacitive micromachined ultrasonic transducers: next-generation arrays for acoustic imaging?  

Microsoft Academic Search

Piezoelectric materials have dominated the ultrasonic transducer technology. Recently, capacitive micromachined ultrasonic transducers (CMUTs) have emerged as an alternative technology offering advantages such as wide bandwidth, ease of fabricating large arrays, and potential for integration with electronics. The aim of this paper is to demonstrate the viability of CMUTs for ultrasound imaging. We present the first pulse-echo phased array B-scan

Oincr Oralkan; A. Sanli Ergun; J. A. Johnson; M. Karaman; U. Demirci; K. Kaviani; T. H. Lee; B. T. Khuri-Yakub

2002-01-01

380

Hidden corrosion detection in aircraft aluminum structures using laser ultrasonics and wavelet transform signal analysis  

Microsoft Academic Search

Preliminary results of hidden corrosion detection in aircraft aluminum structures using a noncontact laser based ultrasonic technique are presented. A short laser pulse focused to a line spot is used as a broadband source of ultrasonic guided waves in an aluminum 2024 sample cut from an aircraft structure and prepared with artificially corroded circular areas on its back surface. The

M. Z. Silva; R. Gouyon; F. Lepoutre

2003-01-01

381

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

382

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

383

Comparison of ultrasonic signals in aircraft skin obtained through experiment and simulation  

Microsoft Academic Search

An ultrasonic pulse-echo technique is used to detect disbonds in adhesive bonds in lap joints and those between aircraft skin and reinforcing doublers. Experimental signals are acquired from fabricated as well as commercial aircraft lap joints. It is observed that the ultrasonic signals from unpainted surfaces contain clearly distinguishable echoes from successive layers of the sample. A better understanding of

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

1991-01-01

384

Analysis of ultrasonic wave propagation in metallic pipe structures using finite element modelling techniques  

Microsoft Academic Search

This paper describes the development of a FEM representing ultrasonic inspection in a metallic pipe. The model comprises two wedge transducer components, water coupled onto the inner wall of a steel pipe and configured to generate\\/receive ultrasonic shear waves. One device is used in pulse-echo mode to analyse any reflected components within the system, with the second transducer operating in

A. Gachagan; A. McNab; P. Reynolds

2004-01-01

385

Dispersion Method Using Focused Ultrasonic Field  

NASA Astrophysics Data System (ADS)

The dispersion of powders into liquids has become one of the most important techniques in high-tech industries and it is a common process in the formulation of various products, such as paint, ink, shampoo, beverages, and polishing media. In this study, an ultrasonic system with a cylindrical transducer is newly introduced for pure nanoparticle dispersion. The acoustics pressure field and the characteristics of the shock pulse caused by cavitation are investigated. The frequency spectrum of the pulse from the collapse of air bubbles in the cavitation is analyzed theoretically. It was confirmed that a TiO2 water suspension can be dispersed effectively using the suggested system.

Jungsoon Kim,; Moojoon Kim,; Kanglyel Ha,; Minchul Chu,

2010-07-01

386

Technique for Measuring Ultrasonic Velocity and Attenuation Spectra in Rocks Under Pressure  

Microsoft Academic Search

An ultrasonic pulse technique has been developed for measuring phase velocity and attenuation spectra in rocks inside a pressure vessel. This technique has been adapted from those used in the nondestructive evaluation field. In essence, a broadband acoustic pulse is directed into a lucite buffer, which is followed by the rock sample and another lucite buffer. The pulse partially reflects

K. W. Winkler; T. J. Plona

1982-01-01

387

Technique for measuring ultrasonic velocity and attenuation spectra in rocks under pressure  

Microsoft Academic Search

An ultrasonic pulse technique has been developed for measuring phase velocity and attenuation spectra in rocks inside a pressure vessel. This technique has been adapted from those used in the nondestructive evaluation field. In essence, a broadband acoustic pulse is directed into a lucite buffer, which is followed by the rock sample and another lucite buffer. The pulse partially reflects

K. W. Winkler; T. J. Plona

1982-01-01

388

Design of efficient, broadband single-element (20-80 MHz) ultrasonic transducers for medical imaging applications.  

PubMed

This paper discusses the design, fabrication, and testing of sensitive broadband lithium niobate (LiNbO3) single-element ultrasonic transducers in the 20-80 MHz frequency range. Transducers of varying dimensions were built for an f# range of 2.0-3.1. The desired focal depths were achieved by either casting an acoustic lens on the transducer face or press-focusing the piezoelectric into a spherical curvature. For designs that required electrical impedance matching, a low impedance transmission line coaxial cable was used. All transducers were tested in a pulse-echo arrangement, whereby the center frequency, bandwidth, insertion loss, and focal depth were measured. Several transducers were fabricated with center frequencies in the 20-80 MHz range with the measured -6 dB bandwidths and two-way insertion loss values ranging from 57 to 74% and 9.6 to 21.3 dB, respectively. Both transducer focusing techniques proved successful in producing highly sensitive, high-frequency, single-element, ultrasonic-imaging transducers. In vivo and in vitro ultrasonic backscatter microscope (UBM) images of human eyes were obtained with the 50 MHz transducers. The high sensitivity of these devices could possibly allow for an increase in depth of penetration, higher image signal-to-noise ratio (SNR), and improved image contrast at high frequencies when compared to previously reported results. PMID:14682638

Cannata, Jonathan M; Ritter, Timothy A; Chen, Wo-Hsing; Silverman, Ronald H; Shung, K Kirk

2003-11-01

389

Elastic Moduli of Boron Carbide/Copper Composites from -40 exp 0 C to 800 exp 0 C by Ultrasonic Methods.  

National Technical Information Service (NTIS)

An ultrasonic through-transmission technique for high attenuating materials was developed to determine the ultrasonic longitudinal and shear velocities in B sub 4 C/Cu composites to 800 exp 0 C. Ultrasonic velocity data was used to calculate Young's modul...

J. H. Gieske

1980-01-01

390

New diamond anvil cells for gigahertz ultrasonic interferometry and X-ray diffraction  

Microsoft Academic Search

Two new diamond anvil cells have been designed for ultrasonic and X-ray diffraction measurements on a single crystal sample up to 6 GPa and 250 ºC. Advances in the generation and transmission of coherent GHz ultrasonic signals with wavelengths of the order of micrometers now make it practical to measure elastic properties of samples small enough to be subjected to

W. A. BASSETT; H.-J. REICHMANN; R. J. ANGEL; H. SPETZLER; J. R. SMYTH

391

Electric spark discharge as an ultrasonic generator in flow measurement situations  

Microsoft Academic Search

In this paper, a gap discharge approach to create acoustic signals for ultrasonic low pressure gas flow measurements is investigated. The objective is to develop an ultrasonic gas flow meter system that is capable of operation in extreme industrial environments. These environments might have extremely high temperatures (1200 °C), moisture, steam, dust, low gas pressure and large transmission distances.Most other types

Emil Martinson; Jerker Delsing

2010-01-01

392

High-frequency transducers and correlation method to enhance ultrasonic gas flow metering  

Microsoft Academic Search

Research activities carried out in past years have shown that in gas networks some constraints exist on the frequency at which ultrasonic transducers can be operated. The study of the transmission and attenuation of the signal and noise mechanisms gives us a defined suitable frequency range (K.R. Wild, A European collaboration to evaluate the application of multi-path ultrasonic gas flow

P Brassier; B Hosten; F Vulovic

2001-01-01

393

NON-CONTACT ULTRASONIC SENSOR FOR DENSITY MEASUREMENT AND DEFECT DETECTION ON WOOD  

Microsoft Academic Search

In this work the problem of measuring density and verifying structural integrity of wooden samples is approached by using non-contact ultrasonic transducers. The time of flight of the ultrasonic waves is measured in transmission mode using cross-correlation algorithms between emitted and received signals. Once known the times of flight, the propagation velocity through the wood, which is proportional to density,

B. Marchetti; R. Munaretto; G. M. Revel; E. Primo Tomasini

394

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

Microsoft Academic Search

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.

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

2007-01-01

395

Investigation of the Ultrasonic Dynamic Viscoelastic Properties of Aqueous Polyethylene Oxide Solutions.  

National Technical Information Service (NTIS)

Some of the viscoelastic properties of aqueous solutions of polyethylene oxide were studied using the method of pulsed torsional wave propagation in the ultrasonic frequency range. Measurements of the changes in attenuation and phase of the wave train in ...

R. J. Prather

1966-01-01

396

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

397

Distance measurement by an ultrasonic system based on a digital polarity correlator  

Microsoft Academic Search

Ultrasonic systems based on a pulse time-of-flight estimation have been widely used for determining the two-dimensional position and orientation of mobile robots inside a room. The problems with existing systems, that use constant-frequency emissions, are mainly related to potential confusion of echoes from previous or subsequent pulses, those of other systems, or from other objects. This paper presents an ultrasonic

Kenji Nakahira; Tetsuji Kodama; Shin Morita; Shigeru Okuma

2001-01-01

398

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

399

Ultrasonic drilling apparatus  

DOEpatents

Apparatus attachable to an ultrasonic drilling machine for drilling deep holes in very hard materials, such as boron carbide, is provided. The apparatus utilizes a hollow spindle attached to the output horn of the ultrasonic drilling machine. The spindle has a hollow drill bit attached at the opposite end. A housing surrounds the spindle, forming a cavity for holding slurry. In operation, slurry is provided into the housing, and into the spindle through inlets while the spindle is rotating and ultrasonically reciprocating. Slurry flows through the spindle and through the hollow drill bit to cleanse the cutting edge of the bit during a drilling operation. 3 figs.

Duran, E.L.; Lundin, R.L.

1988-06-20

400

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

401

Ultrasonic assessment of tooth structure  

NASA Astrophysics Data System (ADS)

A means of assessing the internal structure of teeth based upon use of high frequency, highly localized ultrasound (acoustic waves) generated by a short laser pulse is discussed. Some key advantages of laser-generated ultrasound over more traditional contact transducer methods are that it is noncontact and nondestructive in nature and requires no special surface preparation. Optical interferometric detection of ultrasound provides a complementary nondestructive, noncontact technique with a very small detection footprint. This combination of techniques, termed laser-based ultrasonics, holds promise for future in-vivo diagnostics of tooth health. In this paper, initial results using laser-based ultrasound for assessment of dental structures are presented on an extracted human incisor. Results show the technique to be sensitive to the enamel/dentin, dentin/pulp, and dentin/cementum junctions as well as a region of dead tracts in the dentin.

Blodgett, David W.

2002-06-01

402

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

PubMed Central

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

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

2009-01-01

403

A microprocessor-based ultrasonic limb movement monitoring system.  

PubMed

A system has been devised, using a spark-gap ultrasonic transmitter and an array of four ultrasonic receivers, to monitor the unrestrained movement of a physically handicapped child's fingertip as he attempts to perform some specific task. A microprocessor is used to measure the time taken for a pulsed ultrasonic shock-wave to travel from the fingertip-mounted spark-transmitter to each of the four ultrasonic receivers, and hence compute the Cartesian co-ordinates of the transmitter. It is hoped that this equipment will enable the voluntary components in the poorly-controlled limb movements of some of the physically handicapped children to be isolated and used to control external equipment. PMID:6458740

Brown, A W

1981-10-01

404

Method for the concurrent ultrasonic inspection of partially completed welds  

DOEpatents

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

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

2002-01-01

405

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

406

Ultrasonic Processing of Materials  

SciTech Connect

The goals of this research is to explore the use of high-intensity ultrasonic vibrations for degassing of molten aluminum, grain refinement during solidification, and ultrafine grain formation in the solid metals.

Sklad, Philip S [ORNL; Han, Qingyou [ORNL

2007-01-01

407

The use of radar methods of optimum detection for ultrasonic echo monitoring  

SciTech Connect

The increasing use of radar methods of detecting targets on a background of interference in ultrasonic echo-monitoring of media with high attenuation is pointed out. A review of research carried out at the Moscow Power Institute directed towards improving the parameters of echo-pulse and ultrasonic monitoring, based on the use of multielement scanning and broad band antenna-probes, and optimum filtering (storage and compression) of echo signals when narrow band and broad band ultrasonic pulses in the frequency range from 100 kHz to 1 MHz are radiated into the medium, is given.

Aksenov, V.P.

1982-10-01

408

New acousto-ultrasonic techniques applied to aerospace materials  

Microsoft Academic Search

The use of an NdYAG pulsed laser for generating ultrasonic waves for NDE in resin matrix composites was investigated. A study was conducted of the use of the 1.064 micron wavelength NdYAG pulsed laser with the neat, unreinforced resin as well as graphite fiber\\/polymer composite specimens. In the case of the neat resins it was found that, at normal incidence,

Kautz

1988-01-01

409

Development of ultrasonic methods of hemodynamic measurements. [rheoencephalography/flowmeters  

NASA Technical Reports Server (NTRS)

A pulsed ultrasonic Doppler velocity meter which can be used (by modifying transducers) as a flowmeter for blood circulation was experimentally studied. Calculations and profiles of turbulent and laminar flow within blood vessels are shown. Graphs and charts of transducers are included.

Histand, M. B.; Mcleod, F. D.; Miller, C. W.

1975-01-01

410

Low-megahertz ultrasonic properties of bovine cancellous bone  

Microsoft Academic Search

Ultrasound offers a noninvasive means to detect changes that occur to the density of cancellous bone as a result of degenerative diseases such as osteoporosis. Techniques based on the velocity and frequency dependence of attenuation of ultrasonic pulses propagated through cancellous bone have proven sensitive to bone density. Most previous studies have investigated these two parameters in the frequency range

B. K. Hoffmeister; S. A. Whitten; J. Y. Rho

2000-01-01

411

3J-3 Reciprocal Operation of Ultrasonic Transducers: Experimental Results  

Microsoft Academic Search

Ultrasonic transit-time flow-meters estimate fluid or gas flows from the difference in times of flight of upstream and downstream acoustic pulses. However, any delay differences arising from sources other than the flow to be measured will cause a troublesome \\

Johan Borg; Jonny Johansson; Jan van Deventer; Jerker Delsing

2006-01-01

412

Photoacoustic imaging using an ultrasonic Fresnel zone plate transducer  

Microsoft Academic Search

A photoacoustic (PA) imaging system based on an ultrasonic Fresnel zone plate (FZP) transducer is developed for the purpose of imaging biological tissue. This FZP transducer has a two-zone negative zone plate piezoelectric material pattern, and an optical fibre is integrated with the transducer on the symmetric axis of the zone plates to deliver laser pulses to the sample. The

Hui Wang; Da Xing; Liangzhong Xiang

2008-01-01

413

Thermostatic and dynamic performance of an ultrasonic density probe  

Microsoft Academic Search

The thermally static and dynamic performance of an ultrasonic density probe for liquids is investigated in the density range of 750 to 1300 kg\\/m3 at temperature ranging from 0 to 40°C. The single transducer probe uses a pulse echo technique to obtain the characteristic acoustic impedance of the liquid and, subsequently, the speed of sound through the liquid to obtain

Jan van Deventer; Jerker Delsing

2001-01-01

414

Ultrasonic attenuation measurements in jet-engine nickel alloys  

Microsoft Academic Search

Ultrasonic attenuation plays a role in the inspection of metals, and accurate attenuation values are needed when making probability of detection estimates for internal defects in components. In this work we assess four broadband, pulse\\/echo, immersion methods for measuring attenuation by applying them to coupons of jet-engine nickel alloy. The different methods generally yield very similar results when care is

P. Haldipur; F. J. Margetan; Linxiao Yu; R. B. Thompson; Joseph A. Turner

2001-01-01

415

Damage detection by Acousto-Ultrasonic Location (AUL)  

Microsoft Academic Search

Damage detection in aircraft structures in-situ is important, especially with not visible defects in composite components for a variety of reasons. In the present paper a new technique based on the Acousto-Ultrasonic (AU) concept is introduced, but instead of extracting information from the externally generated pulsed wave, as with AU, the characteristics of waves reflected from defects are measured. In

Z. P. Marioli-Riga; A. N. Karanika; T. P. Philippidis; S. A. Paipetis

1992-01-01

416

Precise ultrasonic ranging based on pseudo-random sequence modulated continuous signal processing  

NASA Astrophysics Data System (ADS)

The ultrasonic ranging equipment usually need to measure the "time of flight", that it takes for acoustic waves to travel the measured distance. Due to the influence of various noises, ultrasonic distance measurement using the pulse signal is difficult to obtain accurate measurement results. Continuous signal phase detected method can achieve the precision measurement of the transmission time, and has a strong noise resistance capability. When single-frequency signals are used, the measurement range is limited to a small extent. This problem can be solved by dual-tone or multi-frequency method. But in short distance ranging applications especial in the restricted space fields, there usually exists strong multiple echoes. Because of the echoes, the ranging accuracy will be significantly decreased. In this paper, a singlefrequency continuous signal modulated by a pseudo-random sequence is used, since the pseudo-random sequence has excellent autocorrelation properties. On the other hand, an improved signal phase estimation algorithm is used to realize the high-precision measurement of TOF. An experimental measurement system was built, and experiments showed that the method can get micron degree precision.

Qiao, Chunjie; Huang, Zhigang; Zhou, Chao

2013-10-01

417

Analysis of ultrasonic frequency response of surface attached fiber Bragg grating.  

PubMed

In recent years, fiber Bragg grating (FBG), for the well-known advantages over other fiber optic sensors, has attracted more attention in ultrasonic inspection for structure health monitoring (SHM). Spectrum shift of FBG to ultrasonic wave is caused by the refractive index profile changing along the FBG, which can be attributed to nonuniform perturbation caused by strain-optic and geometric effects of ultrasonic wave. Response of FBG to the above two effects was analyzed firstly by the V-I transmission matrix model, showing high computing efficiency. Based on this model, spectra response of FBG under changing ultrasonic frequencies was simulated and discussed. In experiment, the system was able to detect a wideband ultrasonic wave ranging from 15 to 1380 kHz. These results would provide a guideline for an FBG-based acoustic detection system design in a specific ultrasonic frequency. PMID:22781246

Li, Zhuoxuan; Pei, Li; Dong, Bo; Ma, Cheng; Wang, Anbo

2012-07-10

418

A Novel Application of Ultrasonic Imaging to Study Smoldering Combustion  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

419

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) [Livermore, CA

1994-01-01

420

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

421

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

422

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

NASA Astrophysics Data System (ADS)

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 arbitrary shape has not yet been achieved. In this work, diffraction of a laser-generated ultrasonic line source at a semi-infinite half-plane is examined using rigorous diffraction theory. Directivity patterns are calculated for a laser line source, for diffraction of a plane wave at a semi-infinite half-plane and for diffraction of an ultrasonic shear wave generated by a laser line. Experimental validation of the theory is performed using laser-generated ultrasonic diffraction of a shear wave at a slot and its subsequent detection with an EMAT receiver sensitive to shear displacements. Results from calculations and experiments show that the directivity of a laser line source is identical to a laser point source in two dimensions if thermal conduction and subsurface optical penetration effects are neglected. Calculations of the directivity pattern for diffraction of an ultrasonic shear wave at a semi-infinite half-plane show that the majority of the diffracted energy propagates in the direction of the incident plane wave with a smaller portion diffracted at all angles. Diffraction of a laser-generated line source at a semi-infinite half-plane shows similar results. Both models indicate that there will not be a sharp shadow boundary for ultrasonic diffraction at a crack. Experiments performed on an aluminum half-cylinder milled with an EDM slot along the radius verify that ultrasonic signals appear in the shadow zone of the crack. Surface scans using the hybrid laser/EMAT system on aluminum plates milled with slots of different sizes show that crack diffraction is a frequency dependent process. Lower frequencies are found to dominate in the shadow zone. These results indicate that crack sizing may be aided by filtering the signals or similar signal processing methods.

Bernstein, Johanna Rebecca

423

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

NASA Astrophysics Data System (ADS)

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, diffraction of a thermoelastic laser-generated ultrasonic line source at a semi-infinite half-plane is examined using rigorous diffraction theory. Directivity patterns are calculated for a laser line source, for diffraction of a plane wave at a semi-infinite half-plane and for diffraction of an ultrasonic shear wave generated by a laser line. Experimental validation of the theory is performed using laser-generated ultrasonic diffraction of a shear wave at a slot and its subsequent detection with an EMAT receiver sensitive to shear displacements. Results from calculations and experiments show that the directivity of a laser line source is identical to a laser point source in two dimensions if thermal conduction and subsurface optical penetration effects are neglected. Calculations of the directivity pattern for diffraction of an ultrasonic shear wave at a semi-infinite half-plane show that the majority of the diffracted energy propagates in the direction of the incident plane wave with a smaller portion diffracted at all angles. Diffraction of a laser-generated line source at a semi-infinite half-plane shows similar results. Both models indicate that there will not be a sharp shadow boundary for ultrasonic diffraction at a crack. Experiments performed on an aluminum half-cylinder milled with an EDM slot along the radius verify that ultrasonic signals appear in the shadow zone of the crack. Surface scans using the hybrid laser/EMAT system on aluminum plates milled with slots of different sizes show that crack diffraction is a frequency dependent process. Lower frequencies are found to dominate in the shadow zone. These results indicate that crack sizing may be aided by filtering the signals or similar signal processing methods. .

Bernstein, J. R.; Spicer, J. B.

2000-05-01

424

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

425

Diffuse ultrasonic scattering in heterogeneous media  

NASA Astrophysics Data System (ADS)

Diffuse ultrasonic backscatter measurements have been especially useful for extracting microstructural information and for detecting flaws in materials. Accurate interpretation of experimental data requires robust scattering models. Quantitative ultrasonic scattering models include components of transducer beam patterns as well as microstructural scattering information. In this dissertation, the Wigner distribution is used in conjunction with the stochastic wave equation to model this scattering problem. The Wigner distribution represents a distribution in space and time of spectral energy density as a function of wave vector and frequency. The scattered response is derived within the context of the Wigner distribution of the beam pattern of a Gaussian transducer. The source and receiver distributions are included in the analysis in a rigorous fashion. The resulting scattered response is then simplified in the single-scattering limit---the singly-scattered response (SSR)---typical of many diffuse backscatter experiments. Diffuse ultrasonic scattering experiments are usually done using a modified pulse-echo technique and utilize the variance of the signals in space as the primary measure to assess microstructure. Thus the SSR model is modified to account for normal and oblique incidence ultrasonic experiments where the wave propagates through planar or curved liquid-solid interfaces. The theoretical model is then compared with experimental results from polycrystalline materials with known microstructure. The research in this dissertation provides a fundamental approach for the multiple scattering within the material which can be exploited in the future for design of new experiments and extraction of other microstructure properties. These results are anticipated to be relevant to ultrasonic nondestructive evaluation of polycrystalline and other heterogeneous solids.

Ghoshal, Goutam

426

Ultrasonic-aided fabrication of gold nanofluids  

PubMed Central

A novel ultrasonic-aided one-step method for the fabrication of gold nanofluids is proposed in this study. Both spherical- and plate-shaped gold nanoparticles (GNPs) in the size range of 10-300 nm are synthesized. Subsequent purification produces well-controlled nanofluids with known solid and liquid contents. The morphology and properties of the nanoparticle and nanofluids are characterized by transmission electron microscopy, scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffraction spectroscopy, and dynamic light scattering, as well as effective thermal conductivities. The ultrasonication technique is found to be a very powerful tool in engineering the size and shape of GNPs. Subsequent property measurement shows that both particle size and particle shape play significant roles in determining the effective thermal conductivity. A large increase in effective thermal conductivity can be achieved (approximately 65%) for gold nanofluids using plate-shaped particles under low particle concentrations (i.e.764 ?M/L).

2011-01-01

427

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

428

Surface nanocrystallization of iron induced by ultrasonic shot peening  

Microsoft Academic Search

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

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

1999-01-01

429

Ultrasonic meters prove reliability on Nova Gas pipeline  

Microsoft Academic Search

Getting the job done efficiently, safely, and economically are the main reasons Nova Gas Transmission Ltd. (NGTL) of Alberta, Canada looked to an ultrasonic gas flow meter for its flow measurement applications. In the past, NGTL relied mainly on orifice plates to measure mainline flow. In 1990, as a result of an increased requirement for reliable mainline measurement, NGTL initiated

Rogi

1995-01-01

430

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

431

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

432

Ultrasonic NDT of building materials based on wave features analysis  

Microsoft Academic Search

An ultrasonic technique has been experimented for non destructive testing of building structures. The Through Transmission Technique has been applied, processing the wave incident on a grid of detecting probes after it has been transmitted through a trachite stone masonry with an inside cavity. Several parameters associated with acoustic waves propagating through the structure have been analyzed and a distribution

Mariangela USAI; Massimo CAMPLANI; Barbara CANNAS; Giovanna CONCU

433

Concentration Distributions during Pulse Jet Mixing  

Microsoft Academic Search

Obtaining real-time, in situ slurry concentration measurements during unsteady mixing can provide increased understanding into mixer performance. During recent tests an ultrasonic attenuation sensor was inserted into a mixing vessel to measure the slurry concentration during unsteady mixing in real time during pulse jet mixer operation. These pulse jet mixing tests to suspend noncohesive solids in Newtonian liquid were conducted

Judith A. Bamberger; Perry A. Meyer

2010-01-01

434

Flexible ultrasonic array system for inspecting thick composite structures  

NASA Astrophysics Data System (ADS)

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

Frankle, Robert S.; Rose, Douglas N.

1995-06-01

435

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

436

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

437

The applicability of a material-treatment laser pulse in non-destructive evaluations  

Microsoft Academic Search

A practical optodynamic study was performed to determine the usability of different lengths of laser pulses for the generation of ultrasonic transients in a solid material. The aim of the study was to evaluate the possibility of a dual use for a laser pulse—for laser material processing, on the one hand, and for the ultrasonic wave generation on the other—with

R. Hrovatin; R. Petkovšek; J. Diaci; J. Možina

2006-01-01

438

Ultrasonic thermoacoustic energy converter.  

PubMed

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

Flitcroft, Myra; Symko, Orest G

2013-03-01

439

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

440

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

441

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

442

Generating Independent Preionizing Pulses for Lasers  

NASA Technical Reports Server (NTRS)

Simple pulse-coupling winding on saturable reactor core lets core act as pulse transformer, passing preionizing pulse from winding to tapered transmission line, then to laser. Laser prepared for independent firing pulse, which follows preionizing pulse. Winding is simple, light in weight, low in bulk and power consumption, and inexpensive.

Pacala, T. J.

1986-01-01

443

Ultrasonic study and physical properties of some borate glasses  

Microsoft Academic Search

The structure of the glass system (75?x)B2O3–xBi2O3–25Li2O, where x=5, 10, 15, and 20mol% was investigated by using pulse-echo technique. Elastic properties of the glass system have been calculated together with Poisson’s ratio and Debye temperature from the measured densities as well as longitudinal and shear ultrasonic velocities at room temperature. Ultrasonic velocity measurements were taken at 4MHz. Estimated parameters based

Yasser B Saddeek

2004-01-01

444

Experimental techniques in ultrasonics for NDE and material characterization  

NASA Astrophysics Data System (ADS)

A development status evaluation is presented for ultrasonics NDE characterization of aerospace alloys and composites in such application as the Space Shuttle, Space Station Freedom, and hypersonic aircraft. The use of such NDE techniques extends to composite-cure monitoring, postmanufacturing quality assurance, and in-space service inspection of such materials as graphite/epoxy, Ti alloys, and Al honeycomb. Attention is here given to the spectroscopy of elastically scattered wave pulses from flaws, the acoustical imaging of flaws in honeycomb structures, and laser-based ultrasonics for the noncontact inspection of composite structures.

Tittmann, B. R.

445

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

446

The ultrasonic ranging and data system for radiological surveys in the UMTRA (Uranium Mill Tailings Remedial Action) Project  

Microsoft Academic Search

The Ultrasonic Ranging and Data System (USRADS) was developed to allow radiation exposure data and positional information to be collected, stored and analyzed in a more efficient manner than currently employed on the (Uranium Mill Tailings Remedial Action (UMTRA) project. USRADS is a portable unit which employs ultrasonics, radio frequency transmissions, and a personal computer. Operational experience indicates that the

C. A. Little; B. A. Berven; M. S. Blair; K. S. Dickerson; D. A. Pickering

1988-01-01

447

Pulse Coupling for Laser Excitation  

NASA Technical Reports Server (NTRS)

Tapered transmission line couples energy from magnetic switch to excimer laser. Transmission line provides constant impedance for pulses from switch and distributes pulses across length of laser as nearly uniform wave fronts. Allows smaller, more efficient magnetic core to be used in switch. Losses and circuit capacitance are less than for full-laser-width line and core.

Pacala, T. J.

1986-01-01

448

Laser ultrasonic generation at the surface of a liquid metal  

SciTech Connect

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

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

1995-01-01

449

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

450

High energy, low frequency, ultrasonic transducer  

DOEpatents

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

Brown, Albert E. (Hayward, CA)

2000-01-01

451

Ultrasonic imaging of the human body  

NASA Astrophysics Data System (ADS)

Ultrasonic imaging is a mature medical technology. It accounts for one in four imaging studies and this proportion is increasing. Wave propagation, beam formation, the Doppler effect and the properties of tissues that affect imaging are discussed. The transducer materials and construction of the probes used in imaging are described, as well as the methods of measuring the ultrasonic field. The history of ultrasonic imaging is briefly reviewed. The pulse-echo technique is used for real-time grey-scale imaging and the factors that limit the spatial and temporal resolutions are considered. The construction and performance of transducer arrays are discussed, together with the associated beam steering and signal processing systems. Speckle and scattering by blood are introduced, particularly in the context of the observation of blood flow by means of the Doppler effect and by time-domain signal processing. Colour flow imaging, and the colour coding schemes used for velocity and power imaging, are explained. The acquisition and display of three-dimensional images are discussed, with particular reference to speed and segmentation. Specialized imaging methods, including endoluminal scanning, synthetic aperture imaging, computed tomography, elasticity imaging, microscanning, contrast agents, and tissue harmonic imaging, are reviewed. There is a discussion of issues relating to safety. Conclusions are drawn and future prospects are considered.

Wells, P. N. T.

1999-05-01

452

Measurement of lung volume and ventilation distribution with an ultrasonic flow meter in healthy infants  

Microsoft Academic Search

Small airway disease in infants is characterised by abnormal lung volume and uneven ventilation distribution. An inert tracer gas washin\\/washout technique using a pulsed ultrasonic flow meter is presented to measure functional residual capacity (FRC) and ventilation distribution in spontaneously breathing and unsedated infants. With a pulsed ultrasound sent through the main stream of the flow meter, flow, volume and

A. Schibler; G. L. Hall; F. Businger; B. Reinmann; J. H. Wildhaber; M. Cernelc; U. Frey

2002-01-01

453

Calibrated Ultrasonic Sound Source.  

National Technical Information Service (NTIS)

To calibrate an ultrasonic microphone of new design a requirement arose for a sound intensity standard at frequencies above 40 kHz. This led to the development of a piezoelectric crystal source whose acoustic output matches that of an ideal piston radiato...

R. W. Hermsen W. R. Babcock

1970-01-01

454

Ultrasonic soldering in electronics.  

PubMed

Ultrasonic (US) soldering of electronic components, as an alternative to flux soldering, is environmentally friendly, improves the quality of soldered connections at the mounting elements after long-term storage, and allows the use of lead-free solders. Methods of US solder melt activation, lead-free solders in US soldering and glass-ceramic capacitor metallization processes have been investigated. PMID:11510223

Lanin, V L

2001-10-01

455

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

456

[Ultrasonic diagnosis of tumors].  

PubMed

In clinical oncology, outpatient ultrasonic investigation helps to assess the nature of the tumor and the spread of malignancy with a high degree of accuracy, so that an adequate treatment could be chosen and initiated as early as possible, and monitored echographically, which is expected to improve its long-term results. PMID:2660302

Pletnev, S D; Nazarova, I S; Mukhtarov, A A; Mazurin, V G

1989-01-01

457

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

SciTech Connect

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

Gieske, J.H.

1980-11-01

458

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

459

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

Microsoft Academic Search

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

Martin Bragg; Rory McMahon; Per Fredrickson; Larry Lynnworth

1999-01-01

460

Multimode-Guided-Wave Ultrasonic Scanning of Materials  

NASA Technical Reports Server (NTRS)

Two documents discuss a method of characterizing advanced composite materials by use of multimode-guided ultrasonic waves. A transmitting transducer excites modulated (e.g., pulsed) ultrasonic waves at one location on a surface of a plate specimen. The waves interact with microstructure and flaws as they propagate through the specimen to a receiving transducer at a different location. The received signal is analyzed to determine the total (multimode) ultrasonic response of the specimen and utilize this response to evaluate microstructure and flaws. The analysis is performed by software that extracts parameters of signals in the time and frequency domains. Scanning is effected by using computer-controlled motorized translation stages to position the transducers at specified pairs of locations and repeating the measurement, data-acquisition, and data-analysis processes at the successive locations. One document presents results of a scan of a specimen containing a delamination.

Roth, Don

2006-01-01

461

Ultrasonic sensing of GMAW: Laser/EMAT defect detection system  

SciTech Connect

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

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

1992-08-01

462

Borehole data transmission apparatus  

DOEpatents

A borehole data transmission apparatus is described whereby a centrifugal pump impeller(s) is used to provide a turbine stage having substantial pressure characteristics in response to changing rotational speed of a shaft for the pressure pulsing of data from the borehole through the drilling mud to the surface of the earth.

Kotlyar, O.M.

1993-03-23

463

Borehole data transmission apparatus  

DOEpatents

A borehole data transmission apparatus whereby a centrifugal pump impeller(s) is used to provide a turbine stage having substantial pressure characteristics in response to changing rotational speed of a shaft for the pressure pulsing of data from the borehole through the drilling mud to the surface of the earth.

Kotlyar, Oleg M. (1739 Grandview #2, Idaho Falls, ID 83402)