Note: This page contains sample records for the topic ultrasonic pulse transmission from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

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

Microsoft Academic Search

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

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

1999-01-01

2

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

3

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

A Pulsed Ultrasonic Flowmeter  

Microsoft Academic Search

A pulsed ultransonic flowmeter has been developed specifically for the simultaneous measurement of blood flow through various major blood vessels in the intact unanesthetized animal. The flow section is a small (1-3 cm) lucite cylinder which is clamped about the blood vessel. Piezoelectric crystals are mounted on the flow section so that bursts of 3-mc sound may be transmitted alternately

D. L. Franklin; D. W. Baker; R. M. Ellis; R. F. Rushmer

1959-01-01

5

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

6

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

7

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Ultrasonic pulsed echo imaging system. 892.1560 Section...Devices § 892.1560 Ultrasonic pulsed echo imaging system. (a) Identification. An ultrasonic pulsed echo imaging system is a device...

2010-04-01

8

21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Ultrasonic pulsed echo imaging system. 892.1560 Section...Devices § 892.1560 Ultrasonic pulsed echo imaging system. (a) Identification. An ultrasonic pulsed echo imaging system is a device...

2009-04-01

9

Ultrasonic flowmetering with reflected pulses  

NASA Astrophysics Data System (ADS)

Consolidated Edison of New York City has expressed the need for a new gasmeter for accurately monitoring large diameter interdistrict gas transmission lines for loss due to theft or leakage. A research effort aimed at developing a new flowmeter for Con Edison is described. The new flowmeter uses ultrasonic flowmetering technology in a novel way to meet Con Edison's four major design specifications: the flowmeter should be accurate to 0.5 percent of totalized flow over one year, it should be much simpler to install than a conventional flowmeter, essentially meaning that excavation be limited to that necessary to expose the upper surface of a buried main; its installation must not require service shutdown; and, the flowmeter should not require zero-flow calibration once installed in the gas main.

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

1984-09-01

10

Through air transmission for ultrasonic nondestructive testing  

Microsoft Academic Search

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

D. Reilly; G. Hayward

1991-01-01

11

Effects of Crack Closure on Ultrasonic Transmission.  

National Technical Information Service (NTIS)

Ultrasonic waves are attenuated as they propagate past the tip of a crack due to the reflection of the energy at the crack face and diffraction at the crack tip. Crack closure modifies the situation since partial transmission can occur at points along the...

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

1983-01-01

12

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

13

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

14

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

15

Ultrasonic unipolar pulse/echo instrument  

DOEpatents

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

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

1993-04-06

16

Pulsed Ultrasonic Transit Time Flowmeter  

Microsoft Academic Search

The difference in effective velocity of sound pulses propagated alternately upstream and downstream through moving blood is a measure of the blood velocity. A blood flowmeter based on this principle has been developed and employed in routine experiments over a period of four years. The travel time of sound pulses passing diagonally through the blood vessel is measured by gating

D. L. Franklin; D. W. Baker; R. F. Rushmer

1962-01-01

17

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

18

Wireless cardiac action potential transmission with ultrasonically inserted silicon microprobes  

Microsoft Academic Search

This paper reports on the integration of ultrasonically inserted horn-shaped cardiac probes with wireless transmission of 3D cardiac action potential measurement for applications in ex vivo preparations such as monitoring the onset of ventricular fibrillation. Ultrasonically inserted silicon horn probes permit reduced penetration force during insertion, allowing silicon, a brittle material, to penetrate cardiac tissue. The probes also allow recording

C. J. Shen; A. Ramkumar; A. Lal; R. F. Gilmour Jr.

2011-01-01

19

Inline Ultrasonic Rheometry by Pulsed Doppler  

SciTech Connect

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

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

2006-12-22

20

Ultrasonic flowmetering with reflected pulses. Final report  

SciTech Connect

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. The new flowmeter uses ultrasonic flowmetering technology in a novel way to meet Con Edison's four major design specifications: the flowmeter should be accurate to 0.5% of totalized flow over one year; it should be much simpler to install than a conventional flowmeter, essentially meaning that excavation be limited to that necessary to expose the upper surface of a buried main; its installation must not require service shutdown; and, the flowmeter should not require zero-flow calibration once installed in the gas main.

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

1984-09-01

21

Characterization of ultrasonic transducer through transmission systems  

NASA Astrophysics Data System (ADS)

Five different designs of broadband piezoelectric ultrasonic transducers are evaluated and compared to determine the effects of various transducer design parameters on the transducer response. The transducer tested include the Acoustic Emission Technology (AET) FC-500 transducers, consisting of a 0.073 cubic centimeters (0.029 in) lead metaniobate piezoelement, 0.035 cm (0.014 in) titanium carbide wearplate and 0.635 cubic centimeters (0.250 in) tungsten epoxy backing layer; the AE-101, a prototype identical to the FC-500 except that it has a 0.035 cubic centimeters (0.014 in) aluminum wearplate; and the AE-100, AE-102, and AE-103, also identical to the FC-500 except that they have backing layers of 0.0 cubic centimeters (no backing), 1.270 cubic centimeters (0.500 in), and 1.905 cubic centimeters (0.750 in), respectively. Pairs of each of the transducers are clamped face-to-face and tested with narrow-band continuous sinusoids and tone bursts (0.4 to 3.0 MHz), and with a broadband input signal (1.0 used pulse).

Blough, J. C.; Lee, S. S.; Williams, J. H., Jr.

1982-12-01

22

Ultrasonic Active Fiber Sensor based on Pulse-echo Method  

Microsoft Academic Search

In this study, the concept of the ultrasonic active fiber sensor (UAFS) system based on the pulse-echo method was newly proposed for several mechanical and environmental sensors. A piezoelectric transducer, which was attached onto the end of the optical fiber, can be used for the ultrasonic wave generator and receiver. The piezoelectric patch was excited at its resonance frequency in

Seung-Hyun Lim; Il-Kwon Oh; Jung-Ryul Lee

2009-01-01

23

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

24

21 CFR 892.1560 - Ultrasonic pulsed echo 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 § 892.1560 Ultrasonic pulsed echo imaging system. (a) Identification....

2013-04-01

25

High current pulse transmission cable  

DOEpatents

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

Parsons, W.M.

1990-09-28

26

Power and Information Transmission to Implanted Medical Device Using Ultrasonic  

Microsoft Academic Search

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

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

2001-01-01

27

Transient acceleration response of a bone-conducted ultrasonic pulse in living human head.  

PubMed

Ultrasonic hearing through bone-conduction is referred to as bone-conducted ultrasound (BCU). Because the perceptual mechanisms of ultrasonic hearing are still unclear, it is necessary to approach the subject from various aspects to clarify such mechanisms; the propagation process of ultrasonic vibration in the head is one of them. To estimate propagation pathways and modes of BCU in living human head, we measured the transient acceleration responses for ultrasonic pulses. The acceleration responses were obtained at the left and right ears simultaneously for left-side, right-side and forehead excitations. Transient responses show that there are several transmission pathways or modes, and the dominant pathways of BCU were identified. PMID:24110109

Hotehama, Takuya; Nakagawa, Seiji

2013-07-01

28

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

29

Force transmission model of a cylindrical linear ultrasonic motor  

Microsoft Academic Search

A force transmission model of a cylindrical linear ultrasonic motor, which uses the longitudinal and the bending hybrid vibration modes, is established in this paper. The analytical model is used for the guidance about the design of the interface and the analyses about the influence of the preload and interface on the motor's performance. Hertz contact and Coulomb friction are

Chen Qiang; Hu Minqiang; Jin Long; Zhang Yu; Xu Zhike; Gu Juping

2007-01-01

30

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

31

Detection of small gas bubble using ultrasonic transmission-mode tomography system  

Microsoft Academic Search

This paper presents the development of an ultrasonic transmission-mode tomography system for the detection of small gas bubble using higher frequency ultrasonic sensors. The selection of the sensors is important and must be suitable to the application design. Consideration on the natural limitation of ultrasonic wave is also noted as the higher the frequency of the ultrasonic transducer, the better

N. M. N. Ayob; M. H. F. Rahiman; Z. Zakaria; S. Yaacob; R. A. Rahim

2010-01-01

32

Wireless cardiac action potential transmission with ultrasonically inserted silicon microprobes  

NASA Astrophysics Data System (ADS)

This paper reports on the integration of ultrasonically inserted horn-shaped cardiac probes with wireless transmission of 3D cardiac action potential measurement for applications in ex vivo preparations such as monitoring the onset of ventricular fibrillation. Ultrasonically inserted silicon horn probes permit reduced penetration force during insertion, allowing silicon, a brittle material, to penetrate cardiac tissue. The probes also allow recording from multiple sites that are lithographically defined. An application-specific integrated circuit has been designed with a 40 dB amplifying stage and a frequency modulating oscillator at 95 MHz to wirelessly transmit the recorded action potentials. This ultrasonically inserted microprobe wireless system demonstrates the initial results in wireless monitoring of 3D action potential propagation, and the extraction of parameters of interest including the action potential duration and diastolic interval.

Shen, C. J.; Ramkumar, A.; Lal, A.; Gilmour, R. F., Jr.

2011-05-01

33

Fuzzy Ultrasonic Testing System with Columnar Rod  

Microsoft Academic Search

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

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

2006-01-01

34

Experimental hardware development for a pulsed ultrasonic data collection facility  

NASA Astrophysics Data System (ADS)

The work reported in this thesis used readily available components to implement a data acquisition system for a pulsed ultrasonic data collection facility. Use of hardware with controlling software is necessary to collect waveforms of acoustic potential at a given distance from the transmitting source. Precise movement and positioning of an acoustic receiver in the collection plane is accomplished by use of an xy coordinate motor-driven slide assembly. A signal generator and transient digitizer transmit and digitize the signal, respectively. These components are brought together synchronously using LabVIEW instrumentation software. This work provides an efficient means to collect waveform data which can be used to verify computer code written previously for the purpose of modeling pulsed ultrasonic acoustic diffraction patterns.

Gatchell, Peter A.

1994-06-01

35

Physical characteristics and mathematical modelling of the pulsed ultrasonic flowmeter  

Microsoft Academic Search

A pulsed ultrasonic Doppler flowmeter for detailed measurements of velocity profiles in man is described. The device projects\\u000a a beam of ultrasound in bursts of 0·4 ?s duration, at 5 MHz, into the flow; the back-scattered signals are processed to produce\\u000a a signal corresponding to the mean velocity over a small region of the flowing stream. The size and shape

Jens E. Jorgensen; Daniel N. Campau; Donald W. Baker

1973-01-01

36

Finite-amplitude, pulsed, ultrasonic beams  

Microsoft Academic Search

An analytical, approximate solution of the inviscid KZK equation for a nonlinear pulsed sound beam radiated by an acoustic source with a Gaussian velocity distribution, is obtained by means of the renormalization method. This method involves two steps. First, the transient, weakly nonlinear field is computed. However, because of cumulative nonlinear effects, that expansion is non-uniform and breaks down at

François Coulouvrat; Kjell-Eivind Frøysa

1995-01-01

37

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

38

Adaptive Equalizer for Pulse Transmission  

Microsoft Academic Search

Results are reported which are of interest in the automatic adaptive equalization of telephone lines or other narrowbandwidth channels where data transmission is limited primarily by intersymbol interference. We describe an algorithm for adjusting the tap gains of a tapped delay line (TDL) equalizer which converges for all channels to the setting, which minimizes the mean-square error (rose) at the

C. Niessen; D. Willim

1970-01-01

39

ESTIMATION OF CONCRETE COMPRESSIVE STRENGTH BY USING ULTRASONIC PULSE VELOCITIES AND ARTIFICIAL NEURAL NETWORKS  

Microsoft Academic Search

Ultrasonic pulse velocity is one of the most popular non-destructive techniques used in the assessment of concrete properties. However it is very difficult to evaluate the test results since the ultrasonic pulse velocity values are affected by a number of factors. In this study a neural network approach has been proposed for the evaluation of concrete compressive strength by the

Serkan Tapkõn; Mustafa Tuncan; Ömer Arõöz; Ahmet Tuncan; Kambiz Ramyar

40

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

Microsoft Academic Search

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

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

1996-01-01

41

Mathematical model of transmission pulse oximetry  

Microsoft Academic Search

A mathematical model of optical propagation in tissue based on the one-dimensional photon diffusion theory is used to analyze the response of transmission pulse oximeters. The model predicts that errors of over 5% oxygen saturation can occur if there are changes in the emission spectra of the LEDs, the fraction of blood in tissue, the hematocrit or the arterial venous

David R. Marble; Peter W. Cheung

1988-01-01

42

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

43

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

NASA Astrophysics Data System (ADS)

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 interfaces. A new approach, the Averaged Transmission Model (ATM), is developed for treating the effects of imperfect contact at the bond interface. This approach is based upon statistical averaging of the transmission coefficients for the various sound paths between source and receiver. The extension of the model for an arbitrary number of rough interfaces is derived. The temperature dependence of sound velocity and ultrasonic attenuation of the materials are important properties. Experimental techniques based on both pulse-echo and laser ultrasonics in through-transmission mode were developed to characterize these properties at temperatures approaching 330°C. Validation of the ATM was accomplished by comparison of model predictions for PEEK polymer and PEEK/AS4 composites to data from resistance welding experiments. These studies were conducted in three phases. Phase one explored the TTU response to temperature at a fixed degree of intimate contact. Model results correlated well to experimental measurements. In phase two, interface structure was controlled to determine the effect of variable contact on the TTU amplitude at a fixed temperature. Model predictions were compared to TTU measurements for both single and dual interface cases with favorable results. In the phase three, model predictions were compared to results of a post-process TTU inspection of isothermally processed resistance welds. Model results were in agreement with experimental over a wide range of processing times. Hertzian contact theory was used to modify the initial degree of contact resulting from consolidation pressure. Strength development in the third-phase welds was determined to be intimate contact controlled, establishing a direct relationship between TTU amplitudes and strength. A near-linear relationship was found, demonstrating the potential for on-line, non-intrusive monitoring of weld strength.

Tackitt, Kirk David

44

Wireless transmission of cardiac action potentials with ultrasonically guided insertion of silicon probes  

Microsoft Academic Search

This paper reports on the coupling of ultrasonically guided cardiac probes with wireless transmission of cardiac action potentials for applications in monitoring the 3D electrical onset of ventricular fibrillation. An application specific integrated circuit has been designed with a 40 dB amplifying stage and a frequency modulating oscillator to wirelessly transmit the recorded action potentials. Combined with the ultrasonically inserted

C. Janet Shen; Abhishek Ramkumar; Amit Lal

2010-01-01

45

Realization of the ultrasonic liquid flowmeter based on the pulse-phase method  

Microsoft Academic Search

This paper describes the practical realization of an ultrasonic liquid flowmeter based on the pulse-phase method using modified tracking technique. The flowmeter is realized as an embedded system. Its functional structure is comprised of: microcomputer, input-output electronics for processing the ultrasonic signal, and blocks for timing and synchronization. Software support is given through a global flow diagram. The main metrological

V. Pavlovi?; B. Dimitrijevi?; M. Stojcev; Lj. Golubovi?; M. Živkovi?; Lj. Stamenkovi?

1997-01-01

46

Low power integrated circuits for an implantable pulsed Doppler ultrasonic blood flowmeter  

Microsoft Academic Search

Describes two custom integrated circuits which were developed for an implantable pulsed Doppler ultrasonic blood flowmeter. Prime design goals were a minimum circuit volume, minimum power consumption, and operation at low supply voltages. The first of the two IC's performs system timing functions and produces the ultrasonic transmit burst. It can deliver up to 40 mW of peak output power

ROBERT W. GILL; J. D. Meindl

1975-01-01

47

Local SAR in parallel transmission pulse design.  

PubMed

The management of local and global power deposition in human subjects (specific absorption rate, SAR) is a fundamental constraint to the application of parallel transmission (pTx) systems. Even though the pTx and single channel have to meet the same SAR requirements, the complex behavior of the spatial distribution of local SAR for transmission arrays poses problems that are not encountered in conventional single-channel systems and places additional requirements on pTx radio frequency pulse design. We propose a pTx pulse design method which builds on recent work to capture the spatial distribution of local SAR in numerical tissue models in a compressed parameterization in order to incorporate local SAR constraints within computation times that accommodate pTx pulse design during an in vivo magnetic resonance imaging scan. Additionally, the algorithm yields a protocol-specific ultimate peak in local SAR, which is shown to bound the achievable peak local SAR for a given excitation profile fidelity. The performance of the approach was demonstrated using a numerical human head model and a 7 Tesla eight-channel transmit array. The method reduced peak local 10 g SAR by 14-66% for slice-selective pTx excitations and 2D selective pTx excitations compared to a pTx pulse design constrained only by global SAR. The primary tradeoff incurred for reducing peak local SAR was an increase in global SAR, up to 34% for the evaluated examples, which is favorable in cases where local SAR constraints dominate the pulse applications. PMID:22083594

Lee, Joonsung; Gebhardt, Matthias; Wald, Lawrence L; Adalsteinsson, Elfar

2011-11-14

48

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

49

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

50

Micropower integrated circuits for an implantable pulsed-doppler ultrasonic blood flowmeter  

Microsoft Academic Search

Novel micropower monolithic timer-exciter and receiver circuits have been developed to implement an implantable pulse-echo doppler ultrasonic blood flowmeter, representing an improved level of sophistication in analog signal processing for biotelemetry.

R. Gill; J. Meindl

1975-01-01

51

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

52

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

53

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

2012-09-11

54

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

55

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

56

Ultrasonic Spectroscopy.  

National Technical Information Service (NTIS)

Various experimental difficulties discussed in the report had to be overcome to be able to adopt spectroscopic procedures for ultrasonic testing and to construct an ultrasonic spectroscope. The ultrasonic pulse-echo spectroscope recently developed and its...

O. R. Gericke

1966-01-01

57

Finite element modeling of heating phenomena of cracks excited by high-intensity ultrasonic pulses  

Microsoft Academic Search

A three-dimensional thermo-mechanical coupled finite element model is built up to simulate the phenomena of dynamical contact and frictional heating of crack faces when the plate containing the crack is excited by high-intensity ultrasonic pulses. In the finite element model, the high-power ultrasonic transducer is modeled by using a piezoelectric thermal-analogy method, and the dynamical interaction between both crack faces

Zhao-Jiang Chen; Jiang Zheng; Shu-Yi Zhang; Xiao-Bing Mi; Kai Zheng

2010-01-01

58

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

59

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

2013-02-24

60

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

61

Reflection and transmission pulse oximetry during compromised peripheral perfusion  

Microsoft Academic Search

The performance of a reflection pulse oximeter and a transmission pulse oximeter was assessed during open-heart surgery when cardiac output, peripheral temperature, pulse pressure, and systolic pressure were low and vascular resisance was high. Before and after extracorporeal circulation (ECC) there was no difference in ability of the sensors to obtain readings and no difference in the accuracy of those

Heikki Pälve

1991-01-01

62

INTENSE MICROWAVE PULSE TRANSMISSION THROUGH ELECTRICALLY CONTROLLED FERRITE PHASE SHIFTERS  

Microsoft Academic Search

Transmission of X-band ~1 MW pulses through a Faraday phase shifter is followed by (a) distortion of the RF envelope if pulse\\u000a is longer than ~ 10 ns, and (b) reduction of the phase shifter effective electric length after a series of pulses. The ferrite\\u000a degradation is reversible: after a cycle of magnetization, the pulse form is reproduced. These effects

N. Kolganov; N. Kovalov; V. Kashin; E. Danilov

63

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

Microsoft Academic Search

The ultrasonic axial transmission technique, used to assess cortical shells of long bones, is investigated using numerical simulations based on a three-dimensional (3D) finite difference code. We focus our interest on the effects of 3D cortical bone geometry (curvature, cortical thickness), anisotropy, and microporosity on speed of sound (SOS) measurements for different frequencies in the MHz range. We first show

Emmanuel Bossy; Maryline Talmant; Pascal Laugier

2004-01-01

64

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 (60KHz, 300W, pH=7). The diameter of the obtained chitin nanofibers could be controlled within 20-200nm by simply adjusting the ultrasonication time. The pulsed ultrasound disassembled natural chitin into high-aspect-ratio nanofibers with a uniform width (19.4nm after 30min 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 600nm) 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

2013-07-24

65

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

66

PREDICTION OF THE MECHANICAL PROPERTIES OF GRANITES BY ULTRASONIC PULSE VELOCITY AND SCHMIDT HAMMER HARDNESS  

Microsoft Academic Search

The present work deals with the use of simple and economical non destructive techniques, ultrasonic pulse velocity and Schmidt hammer to predict the strength and elastic properties of granitic stones that are characteristic in ancient masonry constructions. Good correlations between NDTs and strength and modulus of elasticity were found, which indicate them as appropriate techniques for estimating the mechanical properties.

Graça Vasconcelos; Paulo B. Lourenço; C. S. A. Alves; J. Pamplona

67

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

Microsoft Academic Search

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

2003-01-01

68

New, compact instrument for pulse-echo-overlap measurements of ultrasonic wave transit times  

Microsoft Academic Search

A new instrument is described which permits the travel time of ultrasonic waves to be measured accurately and conveniently by the pulse-echo-overlap method (PEO). The accuracy and versatility of the PEO method are reviewed, and optimal methods of preparing and interrogating samples are presented. Extensive data on a large blank of fused silica are presented. Longitudinal and shear wave velocities

Emmanuel P. Papadakis

1976-01-01

69

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

70

Design Parameters of Pulsed Wave Ultrasonic Doppler Blood Flowmeter  

Microsoft Academic Search

Pulse wave Doppler techniques promise the ability to make more effective measurements of dynamic cardiovascular functions. Quantitative measurement of blood flow can be achieved by using the pulse wave Doppler system. This paper discusses the design parameters of the pulse wave Doppler blood flowmeter (PW Doppler) with respect to the physiological system.

Inan Giiler; Yilmaz Sava?

1998-01-01

71

A pulsed phase measurement ultrasonic flowmeter for medical gases  

Microsoft Academic Search

Pneumotachometers are used to measure instantaneous flowrate in the respiratory gas streams. The presently available devices\\u000a suffer from lack of linearity, slow response times, and gas density sensitivity. A new design of an ultrasonic gas flowmeter\\u000a is presented in this paper: We investigate the acoustic characteristics of ring and piston shaped transducers, and describe\\u000a a sampling method to avoid the

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

1984-01-01

72

Compact, repetitive, pulsed power generators based on transmission line transformers  

Microsoft Academic Search

This paper describes the design and construction of a compact, repetitive pulsed power generator which is based on the use of a transmission line transformer built from a stack of low impedance striplines.The transformer is driven from a Blumlein pulse forming line, which is constructed from an array of barium titanate dielectric tiles and switched by four thyratrons connected in

C. R. Wilson; G. A. Erickson; P. W. Smith

1989-01-01

73

Transmission line pulsed waveform shaping with microwave filters  

Microsoft Academic Search

Impedance mismatches in the standard transmission line pulsed (TLP) measurement system will severely distort the pulsed waveform, but use of matched microwave attenuating filters can transform the setup into a 50-Omega TLP system which produces near-ideal waveforms. In addition, passive, lossless low-pass filters can be used to vary the rise time of the pulse. Detailed measurement and microwave simulation results

Sopan Joshi; Elyse Rosenbaum

2003-01-01

74

Electrodeposition of Ni–Co\\/Al 2O 3 composite coating by pulse reverse method under ultrasonic condition  

Microsoft Academic Search

Ni–Co\\/Al2O3 composite coating was deposited by pulse reverse current (PRC) method under ultrasonic condition. The influence of ultrasonic power on morphology, microstructure, composition, micro-hardness and residual macrostress of composite coating was investigated by means of SEM, TEM, XRF and XRD. The results indicate the composite coating deposited under ultrasonic power becomes uniform, compact and the grains become fine; the composite

L. M. Chang; H. F. Guo; M. Z. An

2008-01-01

75

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

76

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

77

Transmission of intense femtosecond laser pulses into dielectrics  

NASA Astrophysics Data System (ADS)

The interaction of intense, femtosecond laser pulses with a dielectric medium is examined using a numerical simulation. The simulation uses the one-dimensional electromagnetic wave equation to model laser pulse propagation. In addition, it includes multiphoton ionization, electron attachment, Ohmic heating of free electrons, and temperature-dependent collisional ionization. Laser pulses considered in this study are characterized by peak intensities ˜1012-1014W/cm2 and pulse durations ˜10-100fsec . These laser pulses interacting with fused silica are shown to produce above-critical plasma densities and electron energy densities sufficient to attain experimentally measured damage thresholds. Significant transmission of laser energy is observed even in cases where the peak plasma density is above the critical density for reflection. A damage fluence based on absorbed laser energy is calculated for various pulse durations. The calculated damage fluence threshold is found to be consistent with recent experimental results.

Peñano, J. R.; Sprangle, P.; Hafizi, B.; Manheimer, W.; Zigler, A.

2005-09-01

78

Method and apparatus for characterizing reflected ultrasonic pulses  

NASA Astrophysics Data System (ADS)

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

Yost, William T.; Cantrell, John H., Jr.

1991-07-01

79

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

Microsoft Academic Search

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

F. K. LAM

1977-01-01

80

Pulsed Power for a Dynamic Transmission Electron Microscope  

SciTech Connect

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

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

2009-06-25

81

Finite element modeling of heating phenomena of cracks excited by high-intensity ultrasonic pulses  

NASA Astrophysics Data System (ADS)

A three-dimensional thermo-mechanical coupled finite element model is built up to simulate the phenomena of dynamical contact and frictional heating of crack faces when the plate containing the crack is excited by high-intensity ultrasonic pulses. In the finite element model, the high-power ultrasonic transducer is modeled by using a piezoelectric thermal-analogy method, and the dynamical interaction between both crack faces is modeled using a contact-impact theory. In the simulations, the frictional heating taking place at the crack faces is quantitatively calculated by using finite element thermal-structural coupling analysis, especially, the influences of acoustic chaos to plate vibration and crack heating are calculated and analysed in detail. Meanwhile, the related ultrasonic infrared images are also obtained experimentally, and the theoretical simulation results are in agreement with that of the experiments. The results show that, by using the theoretical method, a good simulation of dynamic interaction and friction heating process of the crack faces under non-chaotic or chaotic sound excitation can be obtained.

Chen, Zhao-Jiang; Zheng, Jiang; Zhang, Shu-Yi; Mi, Xiao-Bing; Zheng, Kai

2010-11-01

82

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

83

Ultrasonic ranging and data telemetry system  

DOEpatents

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

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

1990-01-01

84

Note: Fast double pulse system using transmission line characteristic of the pulse forming line  

NASA Astrophysics Data System (ADS)

A fast double pulse system is designed and developed using the transmission line characteristic of the pulse forming line to generate two flat top rectangular pulses with extremely short interpulse repetition interval. The helical pulse forming line (HPFL) is used to generate longer duration rectangular pulses in smaller length. The HPFL inner conductor is made up of 13 turns of SS-304 strip, 39.5 mm wide and 0.5 mm thick wounded on the 168 mm delrin cylinder. The impedance of the HPFL is 22 ?. The 2 turns at the input side of the HPFL are wounded with ethylene propylene rubber tape on the strip. The HPFL is charged to 180 kV in 4 ?s and discharges into a matched load through a spark switch. It generates two flat top rectangular pulses of 90 kV, 100 ns duration with the 30 ns interval between the pulses. The system can be used as fast double pulse source for repetitive pulsed power loads.

Sharma, Surender Kumar; Deb, P.; Sharma, Archana; Shyam, A.

2012-11-01

85

Ultrasonic Spectroscopy of Steel.  

National Technical Information Service (NTIS)

An electronic instrument has been developed which makes it possible to obtain the ultrasonic attenuation spectrum of a solid material. The spectroscope employs the ultrasonic pulse-echo test technique and is equipped with a single ultrasonic transducer wh...

O. R. Gericke

1964-01-01

86

Vacuum transmission lines for pulse sharpening and diagnostics applications  

SciTech Connect

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

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

1987-06-01

87

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

88

Investigation of ultrasonic properties of MAGIC gels for pulse-echo gel dosimetry  

NASA Astrophysics Data System (ADS)

Ultrasound has been proposed as an alternative 3D method to read out dosimetric gels. The ultrasonic properties of MAGIC gel are investigated in relation to producing a dosimetry system based on a pulse-echo technique. The sound speed, attenuation coefficient, and density of MAGIC gel were measured over a range of temperatures and doses. A nonlinear relationship between ultrasonic attenuation and dose was observed, with the attenuation below 10 Gy being approximately constant. The sound speed was 1550.3 ± 1.5 m s-1 at 25 °C with a dose sensitivity of 0.14 ± 0.03 m s-1 Gy-1 both properties changed with temperature and were 1535.4 ± 0.8 m s-1 and -0.08 ± 0.01 m s-1 Gy-1 respectively at 15 °C. The density also varied with temperature and dose, and was 1028.9 ± 0.3 kg m-3 with a dose sensitivity of 0.178 ± 0.004 kg m-3 Gy-1 at 26 °C. The characteristic acoustic impedance of MAGIC gel was calculated to be 1.596 × 106 kg m2 s-1 at 0 Gy and 25 °C. The dose sensitivities measured indicate that changes to the characteristic acoustic impedance caused by irradiation are small, and therefore a reflector that has a similar characteristic acoustic impedance is required to maximise sensitivity of the pulse-echo technique. A suitable material has been developed and the reflection characteristics of the interface between MAGIC gel and the reflector are also temperature dependent. It is concluded that temperature management will be central to the development of any practical pulse-echo dosimetry system.

Atkins, T. J.; Humphrey, V. F.; Duck, F. A.; Tooley, M. A.

2010-11-01

89

Neuro-fuzzy speed tracking control of traveling-wave ultrasonic motor drives using direct pulse width modulation  

Microsoft Academic Search

The traveling-wave ultrasonic motor (TUSM) drive offers many distinct advantages but suffers from severe system nonlinearities and parameter variations especially during speed control. This paper presents a new speed tracking control system for the TUSM drive, which newly incorporates neuro-fuzzy control and direct pulse width modulation to solve the problem of nonlinearities and variations. Increasingly, the proposed control system is

K. T. Chau; S. W. Chung

2002-01-01

90

Ultrasonic NDT of wind turbine blades using contact pulse-echo immersion testing with moving water container  

Microsoft Academic Search

Wind turbine blades are complicated objects for inspection because they have a curved surface, are multi-layered, have variable thickness and are made from anisotropic materials. Ultrasonic contact pulse-echo immersion testing with moving water container has been selected for inspection of wind turbine blades, because this type of the inspection can be performed having access just from the one side of

E. Jasi?nien?; R. Raišutis; R. Šliteris; A. Voleišis; M. Jakas

2008-01-01

91

Arbitrary pulse shape synthesis via nonuniform transmission lines  

SciTech Connect

The discrete inverse scattering technique is used to define the impedance profile for a nonuniform transmission line which reflects an arbitrary waveform. Initially charged nonuniform lines, switched out into a general load, can also be synthesized by this method and are discussed. The direct or layer peeling'' algorithm is applied to generate profiles which were subsequently analyzed using the one-dimensional finite difference method and fabricated in stripline. Excitation for the nonuniform line was done using a charged line connected to a photoconductive silicon switch triggered by a mode locked YLF laser. Several lines were fabricated relevant to amplitude modulation of the master oscillator laser pulse for fusion experiments.

Burkhart, S.C.; Wilcox, R.B. (Lawrence Livermore National Lab., CA (United States))

1990-10-01

92

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

93

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

PubMed

Laser ultrasonic detection is a versatile and highly sensitive tool for the observation of surface waves. In the following study, laser ultrasonic detection is used for the experimental study of spurious normal vibration modes of a disk quartz sensor excited by a voltage pulse. The AT cut crystal (cut of the crystal relative to the the main crystallographic axis is 35.25 degrees) is optimal for generating mainly thickness-shear vibrations (central frequency 6 MHz) on the quartz surface. However, resulting from shear-to-longitudinal and shear-to-surface mode conversion, and from the weak coupling with the other crystallographic axes, other modes (thickness-compressional and bending modes) are always present in the plate response. Since the laser vibrometer is sensitive to normal displacements, the laser investigation shows waves that can be considered as unwanted for the AT quartz used as a shear sensor. The scanned three dimensional (3D) amplitude-space-time signals are carefully analysed using their representation in three dual Fourier domains (space-time, wave number-frequency). Results on the transient analysis of the waves, the normal bending modes and the dispersion curves are shown. PMID:16797645

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

2006-06-05

94

Characterization of Partially Nonlinear Transmission Lines for Ultrashort-Pulse Amplification  

Microsoft Academic Search

Pulse progagation on partially nonlinear transmission lines (PNLTLs), which are transmission lines with regularly spaced bias-dependent capacitors whose capacitance is inversely proportional to line voltage only in some restricted range and takes a constant value outside this range, is investigated for the management of ultrashort pulses. On a PNLTL, two different types of pulse propagation are allowed. One is the

Koichi Narahara

2003-01-01

95

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

96

Method of transmission ultrasonic amplitude and time travel information over a logging cable  

SciTech Connect

This patent describes a method of transmitting data over a cable connecting an ultrasonic logging apparatus and surface equipment. The data derived from an acoustic return from the ultrasonic logging apparatus operating in a well borehole. The ultrasonic logging apparatus generating an acoustic waveform and receiving the acoustic return from the generated acoustic waveform.

Kyle, D.G.

1990-02-06

97

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

98

Noninvasive and localized neuronal delivery using short ultrasonic pulses and microbubbles  

PubMed Central

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

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

2011-01-01

99

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

100

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

NASA Astrophysics Data System (ADS)

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

Bossy, Emmanuel; Talmant, Maryline; Laugier, Pascal

2004-05-01

101

Ultrasonic axial transmission on cortical bone: A 3-D simulation study  

NASA Astrophysics Data System (ADS)

In vivo, cortical bone is currently investigated using ultrasonic velocity measurement in the megahertz frequency range. It is virtually impossible to analytically model the extremely complex field resulting from the interaction of an incident wave with cortical bone, taking into account 3-D geometry, boundary conditions, anisotropic and heterogeneous bone properties. Recently developed simulation methods based on finite difference offer a fertile alternative to inextricable analytic formulations. Wave propagation simulation is applied here to the problem of axial transmission along the radius. 3-D computations showed that different types of head wave propagate along the anisotropic cortex depending on the thickness-to-wavelength ratio. Simulated variations of SOS as a function of thickness are in good agreement with in vivo [Njeh (1999)] and in vivo [Prevrhal (2001)] observations. Cortical porosity leads to a velocity decrease of approximately 50 ms-1 (respectively 25 ms-1) per % of porosity increase in the axial (respectively, radial) direction. When the cortical thickness is larger than one compressional wavelength, the signal velocity reflects bone properties over a depth of about half a wavelength. Numerical simulation brings an insightful view into the influence of several bone properties on signal velocity, and can also be of great value in testing inverse calculation procedures.

Bossy, Emmanuel; Talmant, Maryline; Laugier, Pascal

2003-10-01

102

Monitoring early age mortar using a pulse-echo ultrasonic guided wave approach  

NASA Astrophysics Data System (ADS)

A pulse-echo ultrasonic guided wave approach that characterizes the setting and hardening of early age mortar during the first twenty-four hours of hydration is presented. The method invokes the fundamental torsional mode on the free end of a cylindrical steel rod partially embedded in mortar and monitors the reflected signals. Both the reflection from the end of the rod and the reflection from the point where the waveguide enters the mortar are monitored. The evolution of the mortar properties is related to both the energy leaked into the surrounding mortar and the energy reflected at the entry point. Results show that the technique is useful for monitoring the development of the mechanical properties of varying water-cement ratios (w/c = 0.40, 0.50, and 0.60). In addition, the effects of chemical (accelerant and retardant) and mineral (silica fume and fly ash) admixtures on the guided wave behavior were also studied. Time of setting and compressive strength measurements have been performed on the various mortar mixtures. The change in signal strength of the end- and entry-reflection of the guided wave appears to be correlated to the mortar setting times and compressive strength, respectively. The ability of this method to only require access to one side of the specimen makes it attractive for the development of a system that monitors in-situ cementitious materials.

Borgerson, Jacob L.; Reis, Henrique

2007-05-01

103

Decoupling of Getting Up Detection Device Using Ultrasonic Radar by Changing Duty Ratio of Transmission Wave  

NASA Astrophysics Data System (ADS)

The decline in the quality of patient's safety control is a problem, because the number of caretakers is reduced by the acceleration of demographic aging in an elder care facility. Especially, the detection of getting up from the bed is very important for preventing patients from falling and wandering unbreakable. In our previous study, we have developed the getting up detection device with an ultrasonic radar, which is safe, cheap, and break-proof. However, if there are many patients in a ward, it is difficult to use some ultrasonic radars. The reason is that if some ultrasonic radars, which have the same frequency, are used in same ward, the ultrasonic signals are coherent with each other. To solve this problem, we propose a novel incoherent method. This method is achieved by improving the software in the device at a low cost.

Yamada, Yo; Tanaka, Kanya; Haruyama, Kazuo; Wakasa, Yuji; Akashi, Takuya

104

Ultrasonic detection of photothermal interaction of lasers with tissue using a pulsed Doppler system  

NASA Astrophysics Data System (ADS)

Thermal therapy using various heating sources such as lasers or microwaves to destroy benign and malignant lesions has recently gained widespread acceptance. However, the accurate prediction of thermal damage in tissue according to theoretical or computer modeling is difficult and unreliable due to target variability with respect to physical properties, geometry, and blood perfusion. Thus, one of the major obstacles to application of thermal therapies has been the lack of a noninvasive, real-time method that could determine the extent and geometry of treated tissue. To evaluate the effects of laser heating on tissue, we have developed an analog-digital hybrid Doppler ultrasound system to measure the phase and amplitude of ultrasonic echoes returned from the heated tissue. The system consists of an eight-gate pulsed Doppler detector, a 16-channel 12-bit A/D converter, and a signal analysis and visualization software package. In vitro studies using canine liver showed two distinct types of modulation of the echoes along the ultrasound beam path during laser irradiation using an 810 nm diode laser. Type 1 signals showed a small and slow variation in amplitude and phase, and were attributed to tissue coagulation. Type 1 signals showed a small and slow variation in amplitude and phase, and were attributed to tissue coagulation. Type 2 signals showed large and rapid variations in amplitude and phase which usually appeared after tissue surface explosion and were indicative of tissue ablation. We hypothesize that the observed phase changes in type 1 signals are due to thermal effects within the tissue consistent with tissue expansion and contraction while the phase changes in type 2 signals are likely due to formation and motion of gas bubbles in the tissue. A further development of the Doppler ultrasound technique could lead to the generation of feedback information needed for monitoring and automatic control of thermal treatment using various heating modalities such as laser, high intensity focused ultrasound, microwaves, or radio frequency waves.

Ying, Hao; Azeemi, Aamer; Hartley, Craig J.; Motamedi, Massoud; Bell, Brent A.; Rastegar, Sohi; Sheppard, L. C.

1995-05-01

105

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

106

21 CFR 1050.10 - Ultrasonic therapy products.  

Code of Federal Regulations, 2010 CFR

...of an ultrasonic therapy product that affects... (t). (20) Pulse duration means...wave expressed in pulses per second (pps...25) Ultrasonic therapy product means...of the ultrasonic therapy product shall be clearly...following information: Pulse duration...

2012-04-01

107

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

108

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

109

Standardization of the transmission line pulse (TLP) methodology for electrostatic discharge (ESD)  

Microsoft Academic Search

Standardization of the methodology of transmission line pulse (TLP) testing has become a necessary reality as it becomes a common place practice in the ESD discipline. This paper discusses the development and method of a TLP standard practice.

Steven H. Voldman; Robert Ashton; Jon Barth; David Bennett; Joseph Bernier; M. Chaine; J. Daughton; E. Grund; M. Farris; H. Gieser; L. G. Henry; M. Hopkins; H. Hyatt; M. I. Natarajan; P. Juliano; T. J. Maloney; B. McCaffrey; L. Ting; E. Worley

2003-01-01

110

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

111

Physical sources of registration erros in pulse-echo ultrasonic systems  

Microsoft Academic Search

The extent to which ultrasonic beams are distorted under normal contact-scanning conditions has been investigated. It has\\u000a been shown that considerable deformation of the beam occurs on passage through a human calf. Deviation and divergence effects\\u000a are small, but the deformation could lead to registration errors of the order of 20 mm in standard diagnostic ultrasonic equipment.

M. Halliwell; R. A. Mountford

1973-01-01

112

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

113

High power pulse burst generation by soliton-type oscillation on Nonlinear Lumped Element Transmission Lines  

Microsoft Academic Search

Nonlinear lumped element transmission line (NLETL) technology has potential value as a source of high power RF pulse burst waveforms. Recent work by the pulsed power & plasma physics group at the University of Oxford has provided a comprehensive analysis of key trends relevant to the design of such lines, and an enhanced understanding of the phenomenon by which the

J. D. Darling; Paul W. Smith

2009-01-01

114

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

115

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

116

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

117

Slow electromagnetic pulse propagation through a narrow transmission band in a coaxial photonic crystal  

Microsoft Academic Search

We demonstrate the slow group-velocity propagation of electromagnetic pulses through a narrow transmission band of a simple coaxial photonic crystal. The narrow transmission band was formed by creating a defect in a periodic coaxial cable filter which resulted in a narrow-frequency passband within an otherwise forbidden band stop region. Strong normal dispersion within this region causes the group velocity of

J. N. Munday; W. M. Robertson

2003-01-01

118

Ultrasonic Study of Positive-Temperature-Coefficient Ceramics  

NASA Astrophysics Data System (ADS)

Shear and compressional wave velocities in (Ba0.996Y0.004)TiO3 semiconductive ceramics were accurately measured by the pulse transmission method over the temperature range between 20°C and 210°C. The temperature dependence of the ultrasonic wave velocities exhibits a marked feature at the characteristic temperatures of transition in resistivity. The elastic moduli were calculated using ultrasonic data.

Kashiwagura, Nobuo; Yoshida, Osamu; Kobayashi, Masakazu; Nakata, Kentaro; Mizuno, Shinji; Kamioka, Hiroaki

2004-05-01

119

Airborne ultrasonic inspection in carbon/carbon composite materials  

NASA Astrophysics Data System (ADS)

In this work, a carbon/carbon (C/C) composite material was nondestructively characterized with non-contact ultrasonic methods using automated acquisition scanner as well as contact ultrasonic measurement because (C/C) composite materials have obvious high price over conventional materials. Because of permeation of coupling medium such as water, it is desirable to perform contact-less nondestructive evaluation to assess material properties and part homogeneity. Also through transmission mode was performed because of the main limitation for air-coupled transducers, which is the acoustic impedance mismatch between most materials and air. Especially ultrasonic images and velocities for C/C composite disk brake was measured and found to be consistent to some degree with the non-contact and contact ultrasonic measurement methods. Low frequency through-transmission scans based on both amplitude and time-of-flight of the ultrasonic pulse were used for mapping out the material property inhomogeneity. Measured results were compared with those obtained by the motorized system with using dry-coupling ultrasonics and through transmission method in immersion. Finally, results using a proposed peak-delay measurement method well corresponded to ultrasonic velocities of the pulse overlap method.

Yang, In-Young; Kim, Young-Hun; Park, Je-Woong; Hsu, David K.; Song, Song-Jin; Cho, Hyun-Jun; Kim, Sun-Kyu; Im, Kwang-Hee

2007-10-01

120

Transmission Conditions of Vibration Stresses to Welding Specimens of Ultrasonic Plastic Welding using Various Two-Vibration-System Equipments  

NASA Astrophysics Data System (ADS)

Ultrasonic plastic welding is applied for welding various thermoplastic materials and is widely used in various industrial fields. The two-vibration-system welding method and a high frequency equipment are effective in improving the welding characteristics. A high frequency 90 kHz system can weld plastic sheets under a 1/3 velocity amplitude as compared with that of a low 27 kHz system, but it is difficult to weld large specimens successfully because a high frequency vibration stress cannot be transmitted uniformly due to the stress relaxation effect by the small vibration displacement. To improve the direct welding characteristics, three types of two-vibration-system ultrasonic welding equipments using linear vibration loci of (1) 90 kHz and 27 kHz longitudinal vibration systems, (2) 90 kHz longitudinal and 20 kHz torsional vibration systems, and elliptical vibration loci of (3) 27 kHz complex vibration systems are studied. Transmission conditions of the vibration stresses are measured by pressure sensitive films (Prescale) which are inserted between the plastic sheets. It was shown that a high frequency vibration stress with a small displacement amplitude may be induced uniformly in the welding specimens by combining a low frequency vibration with large displacement amplitude. These welding systems are effectively used to join plastic sheets successfully.

Tsujino, Jiromaru; Uchida, Takako; Ohkusa, Kunifumi; Adachi, Tatsuya; Ueoka, Tetsugi

1998-05-01

121

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

Microsoft Academic Search

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

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

1986-01-01

122

Quantization Errors of the Echoes in Ultrasonic Pulsed Flowmeter Employing Time Domain Correlation  

Microsoft Academic Search

The implementation of Time Domain Correlation Method for blood flow velocity estimation requires the conversion of the reflected ultrasonic signals into digital format in order that the computer can be utilized to investigate the technique. A number of quantization errors, namely, that the A\\/D has a finite bit resolution, only a limited number of samples of the waveform may be

?nan Güler; Yilmaz Sava?

1997-01-01

123

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

124

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

125

Received Pulse from an Aerial Ultrasonic Sensor Affected by Temperature and Relative Humidity  

Microsoft Academic Search

In order to develop an aerial back sonar for a car, we predicted the waveforms of the received pulse calculated by the finite-difference time-domain (FDTD) method. The echo pulses reflected from the obstacle were calculated as a function of the object's height, the changing temperature and relative humidity in air. The maximum amplitudes of received pulses were changed by about

Yasuhiro Yamada; Takenobu Tsuchiya; Nobuyuki Endoh

2003-01-01

126

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

127

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

128

Time-domain differentiation of optical pulses in reflection and in transmission using the same resonant grating  

NASA Astrophysics Data System (ADS)

Propagation of an optical pulse through a diffraction grating that has a resonance near the pulse central wavelength is discussed. We show that under definite conditions the envelopes of reflected and transmitted pulses may represent the derivative of the incident pulse envelope. Based on the resonance representation of the reflection and transmission spectra, the comparative analysis of the energy efficiency and accuracy of grating-based differentiators operating in reflection and transmission is conducted. A resonant diffraction grating for differentiation of ps-pulses in reflection and in transmission is designed within the framework of the rigorous electromagnetic theory.

Bykov, D. A.; Doskolovich, L. L.; Golovastikov, N. V.; Soifer, V. A.

2013-10-01

129

Ultrasonic diffraction tomography by pulse-plane wave: experimental result by frequency synthesis method.  

PubMed

Diffraction tomography is a technique for imaging with acoustic fields in which parameter, such as reflective index, sound velocity, etc., can be mapped from scatter wave resulting from insonifying the object with a plane wave at a single temporal frequency. By solving the direct scattering problem, the scattered field can be presented in term of scattering parameters. Different inversion techniques can be applied to take advantage of the linearization process of the non-linear wave equation describing wave propagation in heterogeneous media under a limited class of scattering. Specifically, when the scattering effect is weak, one can invoke the Born or Rytov approximation and thus derive the generalized Fourier slice theorem to reconstruct the cross-section of the insonified object. Although diffraction tomography is a promising technology for medical application as it provides a quantitative ultrasonic image, its realization toward medical use is still far-to-go, and this may be due to the complexity of the hardware involved. In this research we investigate a potential use of diffraction tomography for medical application by using a delicate-designed ultrasonic computerized tomographic system. The contribution of the paper is that we have purposed to frequency synthesis method (FSM) that uses 3 frequency components of the Fourier transform of scattered filed, i.e. the center frequency and the -3 dB from center frequency of both side, to fill Fourier space for the generalized Fourier slice theory. The reconstructed ultrasonic image from such theory provides a very promising result. PMID:17282572

Tangtisanon, G; Jaruwongrunsee, K; Withayachumnankul, W; Hamamoto, K; Pintavirooj, C; Sangworasil, M

2005-01-01

130

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

Microsoft Academic Search

This report discusses the effects of the late-time high-altitude electromagnetic pulse (HEMP) on electrical transmission and distribution (T&D) systems. This environment, known as the magnetohydrodynamic electromagnetic pulse (MHD-EMP), is a very slowly varying electric field induced in the earth's surface, similar to the field induced by a geomagnetic storm. It can result in the flow of a quasi-dc current in

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

1992-01-01

131

Transmission and reflection properties of incident pulse in a dielectric slab doped with quantum dot  

NASA Astrophysics Data System (ADS)

In this paper, transmission and reflection properties of incident pulse in a dielectric slab which doped by quantum dot nanostructure via electron tunneling is studied. It is shown that by using the electron tunneling in a quantum dot, the transmission and reflection coefficients can be controlled at different wavelengths. Therefore, this model can be used as an all-optical filter which is suitable for next generation of all optical communication systems.

Asadpour, Seyyed Hossein; Soleimani, Hamid Rahimpour

2013-10-01

132

Ultrasonic pulse-inversion fundamental imaging with liposome microbubbles at 25-50 mhz  

Microsoft Academic Search

Pulse inversion based fundamental imaging was proposed for the enhancement of contrast detection in a previous study. Performance of the imaging method was tested with a commercial contrast agent (Levovist®) at 1.5-3 MHz. In this study, we applied pulse inversion fundamental imaging at 25-50 MHz with liposome microbubbles that were produced in-house. The pulse inversion technique involves two firings with

Chen-Han Li; Ai-Ho Liao; Ja-An Ho; Pai-Chi Li

2005-01-01

133

Design and implementation of 800Mbps 16-QAM pulse shaping filter in high speed satellite transmission  

NASA Astrophysics Data System (ADS)

This paper presents the design procedure and implementation result of 800Mbps 16-QAM pulse shaping filter for payload data transmission system of remote sensing satellite. In order to achieve the high speed pulse shaping filter adapting to the current hardware components, the 16-QAM constellation mapping and the pulse shaping have been combined. Meanwhile, the poly-phase structure of FIR and the distributed algorithm based on look-up table have been used in favor of high speed shaping filter calculation in FPGA. In addition, the 800Mbps 16-QAM pulse shaping filter prototype is realized on the hardware by using the parallel circuit architecture and the high speed circuit technique. The test results have been shown to prove that the design method of the pulse shaping filter can be effectively applied to the high speed payload transmitter of remote sensing satellite.

Hu, Junjie; Cheng, Xin; Xiong, Weiming; Chen, Xiaomin

2009-12-01

134

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

Microsoft Academic Search

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

Vladimir Ermolov; Jyrki Stor-Pellinen; Mauri Luukkala

1996-01-01

135

Imaging of a spatial distribution of preferred orientation of crystallites by pulsed neutron Bragg edge transmission  

NASA Astrophysics Data System (ADS)

A pulsed neutron transmission coupled with a two-dimensional position sensitive neutron detector gives a time-of-flight spectrum at each pixel of the detector, which depends on the total cross-sections of materials. In order to extract quantitative information of the preferred orientation included in the Bragg scattering total cross-section data, a spectral analysis software for the 2D imaging has been developed, and the transmission data of an unbent iron plate were analyzed. The 2D images with respect to the preferred orientation were successfully obtained, and the effectiveness of spectroscopic neutron transmission imaging was indicated.

Sato, H.; Takada, O.; Iwase, K.; Kamiyama, T.; Kiyanagi, Y.

2010-11-01

136

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

Microsoft Academic Search

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

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

2001-01-01

137

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

138

The allowable pulse parameters in the ultrasonic examination of austenitic stainless steel welded pipe  

Microsoft Academic Search

The ultrasonic CS-technique has been proved to be applicable to the shear wave angle beam examination of welds of austenitic\\u000a stainless steel longitudinally welded pipe. It enhances the signal-to-noise ratio especially in the axial-scan flaw-detection\\u000a of welded welds where the previously recommended broad-band transducer-technique did not give sufficient signal-to-noise ratio.\\u000a The CS-technique tends to be effective for reflectors which convert

Taro Maeda; Shoji Inoue; Suenori Mori

1984-01-01

139

The Application of Transmission-Line-Pulsing Technique On Electrostatic Discharge Protection Devices  

Microsoft Academic Search

In the advanced deep-submicron CMOS technology, it is more difficult to prevent damages from the ESD (Electrostatic Discharge) stresses. To understand the physical characteristics and ESD robustness of protection devices, a transmission line pulsing generator (TLPG) system had been set up in several companies to measure the secondary breakdown characteristics of the protection devices. The ESD level of ESD protection

Tung-Yang Chen; Ming-Dou Ker; Chung-Yu Wu

140

Traveling-wave pulse on a superconductive active transmission line using resonant tunneling diodes  

NASA Astrophysics Data System (ADS)

Analytic study and computer experiment investigations on a superconductive active transmission line using resonant tunneling diodes (RTDs) are discussed. It is shown, based on nonlinear wave propagation effects, that the line supports pulse propagation appearing as pairs of kink–antikink profiles. This behavior is due to compensation between the effects of amplification and dissipation along the network.

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

2013-10-01

141

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

142

Novel pulse amplifying circuits based on transmission lines of different characteristic impedance  

NASA Astrophysics Data System (ADS)

Two novel circuits used to amplify electric pulses by the coupling of transmission lines of different characteristic impedance are described. The circuits are intended for doubling voltage pulses and for doubling current pulses. The former is composed by a R0 transmission line closed on a set of two 2R0 storage lines connected in parallel, while the latter is composed by a R0 transmission line closed on a set of two R0/2 storage lines connected in series. The length of every storage line is half of input-pulse length. In both circuits, one storage line is characterized by an open extremity and the other line by a closed extremity. Connecting opportunely the storage lines to suitable load resistors, 4R0 and R0/4, for the circuit having parallel and series connected lines, respectively, a twice of the output pulse intensity is obtained. Such devices are very suitable to generate high intensity voltage and/or current peaks which are very interesting in the field of the accelerators. Both circuit behaviours have been theoretically studied and verified by computer simulations.

Belloni, F.; Doria, D.; Lorusso, A.; Nassisi, V.

2006-01-01

143

Reflectance Pulse Oximetry from Core Body in Neonates and Infants: Comparison to Arterial Blood Oxygen Saturation and to Transmission Pulse Oximetry  

Microsoft Academic Search

OBJECTIVE: To compare pulse oximetry oxygen saturation (SpO2) measured by a novel reflectance method from core body to arterial oxygen saturation (SaO2) in neonates and infants. Transmission pulse oximetry (TPO) was measured for comparison.STUDY DESIGN: We monitored 18 infants by the two pulse oximeters simultaneously. The reflectance pulse oximetry (RPO) (PRO2, ConMed, Utica, NY) was measured on the upper back

Amir Kugelman; Yoram Wasserman; Frida Mor; Leonid Goldinov; Yoav Geller; David Bader

2004-01-01

144

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

145

Experimental spatial sampling study of the real-time ultrasonic pulse-echo BAI-mode imaging technique.  

PubMed

The ultrasonic pulse-echo backscattered amplitude integral (BAI)-mode imaging technique has been developed to inspect the seal integrity of hermetically sealed, flexible food packages. With a focused 17.3-MHz transducer acquiring radio frequency (RF) echo data in a static rectilinear stop-and-go pattern, this technique was able to reliably detect channel defects as small as 38 microm in diameter and occasionally detect 6-microm-diameter channels. This contribution presents our experimental spatial sampling study of the BAI-mode imaging technique with a continuous zigzag scanning protocol that simulates a real-time production line inspection method in continuous motion. Two transducers (f/2 17.3 MHz and f/3 20.3 MHz) were used to acquire RF echo data in a zigzag raster pattern from plastic film samples bearing rectilinear point reflector arrays of varying grid spacings. The average BAI-value difference (deltaBAI) between defective and intact regions and the contrast-to-noise ratio (CNR) were used to assess image quality as a function of three spatial sampling variables: transducer spatial scanning step size, array sample grid spacing, and transducer -6-dB pulse-echo focal beam spot size. For a given grid size, the deltaBAI and CNR degraded as scanning step size in each spatial dimension increased. There is an engineering trade-off between the BAI-mode image quality and the transducer spatial sampling. The optimal spatial sampling step size has been identified to be between one and two times the -6-dB pulse-echo focal beam lateral diameter. PMID:12744399

Yin, Xiangtao; Morris, Scott A; O'Brien, William D

2003-04-01

146

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

147

Performance comparison of RZ pulse formats in PDM-16QAM high rates transmissions with optical pre-filtering  

NASA Astrophysics Data System (ADS)

The digitally modulated signals spectral density depends directly on pulse format used for information symbols transmission. The modulated signal spectral occupancy can be modified according to the channel frequency response to facilitate information retrieval at the receiver. New generation of coherent optical transmission systems operating at high rates are subject to various bandwidth restrictions aspects, such as electronic components limitations and optical filtering via ROADMs deployed on networks. As noted in technical literature, the RZ pulse formats have some advantages compared to traditional NRZ pulses in optical fiber transmissions. In particular, RZ pulses have a better performance in situations where nonlinear effects of the fiber severely impact the quality of transmission. Among other situations, this occurs in systems that employ modulation formats for high order QAM (16QAM, 64QAM, etc.). Moreover, since RZ pulses have shorter duty cycle, temporal spread of the transmitted symbols causes less performance degradation due to ISI compared with NRZ pulses. This report presents results of experiments carried out in a 226 km recirculation loop, to evaluate the performance of NRZ, RZ 67%, 50% RZ and RZ 33% pulse shapes in a transmission of DP-16QAM (or PDM-16QAM). As application it is proposed and experimentally demonstrated a transmission system that employ 28 GBaud dual carrier PDM-16QAM channels operating with a total line rate of 448 Gb/s each, utilizing RZ pulse format and carrier narrow pre-filtering to increase spectral efficiency of transmission, aggregating a 400G channel in a 75 GHz WDM grid.

Silva, E. P.; Carvalho, L. H. H.; Lopes, M. L.; Ribeiro, V. B.; Bordonalli, A. C.; Oliveira, J. C. R. F.

2013-01-01

148

Nonlinear electromechanical response of the ferroelectret ultrasonic transducers  

Microsoft Academic Search

The ultrasonic transmission between two air-coupled polypropylene (PP) ferroelectret (FE) transducers in dependence on the\\u000a amplitude of the high-voltage exciting pulse revealed a strongly nonlinear electromechanical response of the FE transmitter.\\u000a This phenomenon is described by a linear increase of the inverse electromechanical transducer constant of the PP FE film with an increase of the exciting electrical pulse amplitude. Enlargement

Joachim Döring; Viktor Bovtun; Jürgen Bartusch; Anton Erhard; Marc Kreutzbruck; Yuriy Yakymenko

2010-01-01

149

Transmission analysis of ultrasonic Lamb mode conversion in a plate with partial-thickness notch.  

PubMed

Mode conversions of Lamb waves can occur upon encountering damage or defect such as a notch, leading to newly-converted modes apart from wave reflection and transmission. In this paper, the transmission of the fundamental Lamb modes symmetrical S0 and anti-symmetrical A0 with anti-symmetrical notches were investigated in steel plates within the relatively short propagation distance. The group velocity and modal energy of the converted modes were analyzed using simulations and experiments. Two-dimensional finite difference time domain (2D-FDTD) method was employed to calculate the scattering field and extract numerical trends for simulation study and experimental confirmation. Both simulations and experiments revealed that the apparent group velocities of the converted modes in the transmitted signals subject to the notch positions. To describe the mode conversion degree and evaluate the notch severity, wave packets of the originally-transmitted modes and newly-converted modes were separated and corresponding mode energy percentages were analyzed at different notch severities. Frequency-sweeping measurements illustrated that the modal energy percentages varied monotonically over the notch-depth increase with a statistically consistency (R=1.00, P<0.0004). PMID:23916666

Xu, Kailiang; Ta, Dean; Su, Zhongqing; Wang, Weiqi

2013-07-18

150

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

151

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

152

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

153

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

SciTech Connect

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

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

2006-01-23

154

On the transmission of a fractal pulse in a noisy fiber-optic channel  

NASA Astrophysics Data System (ADS)

A numerical experiment on the transmission of a fractal pulse through a single-mode optical fiber (with allowance for chromatic dispersion) has been carried out. The desired signal was transferred along with a masking noise signal. It is shown that efficient separation of fractal signal from noise at the output of fiberoptic communication line calls for knowledge of not only the fractal signal code, but also the dispersion coefficient of the optical fiber.

Malyshev, G. S.; Raevskii, A. S.

2013-09-01

155

Flashover vulnerability of transmission and distribution lines to high-altitude electromagnetic pulse (HEMP)  

SciTech Connect

This paper estimates the vulnerability of transmission and distribution lines to flashover from the electromagnetic pulse generated by a nuclear detonation 400 kilometers above the earth. The analysis consists of first determining the cumulative probability of induced-voltage on three-phase lines, including shield and neutral conductors, for four operating voltages and then comparing these stresses to estimates of line insulation strength. 11 refs., 9 figs., 5 tabs.

Kruse, V.J.; Liu, T.K.; Tesche, F.M.; Barnes, P.R.

1989-01-01

156

Structure of Virioplankton in the Charente Estuary (France): Transmission Electron Microscopy versus Pulsed Field Gel Electrophoresis  

Microsoft Academic Search

Changes in the composition of viral communities were investigated along a salinity gradient and at different times by means\\u000a of transmission electron microscopy (TEM) and pulsed field gel electrophoresis (PFGE). Samples were collected in fresh (Charente\\u000a River), estuarine (Charente Estuary), and coastal (Pertuis d'Antioche, French Atlantic coast) waters. Both methods revealed\\u000a similar patterns in viral community structure with a dominance

J. C. Auguet; H. Montanié; P. Lebaron

2006-01-01

157

A Low-Power High-Speed Ultra-Wideband Pulse Radio Transmission System  

Microsoft Academic Search

We present a low-power high-speed ultra-wideband (UWB) transmitter with a wireless transmission test platform. The system is specifically designed for low-power high-speed wireless implantable biosensors. The integrated transmitter consists of a compact pulse generator and a modulator. The circuit is fabricated in the 0.5-mum silicon-on-sapphire process and occupies 420 mum times 420 mum silicon area. The transmitter is capable of

Wei Tang; Eugenio Culurciello

2009-01-01

158

Transmission of stationary nonlinear optical pulses in dispersive dielectric fibers. I. Anomalous dispersion  

Microsoft Academic Search

Theoretical calculations supported by numerical simulations show that utilization of the nonlinear dependence of the index of refraction on intensity makes possible the transmission of picosecond optical pulses without distortion in dielectric fiber waveguides with group velocity dispersion. In the case of anomalous dispersion (?2???k2>0) discussed here [the case of normal dispersion (?2???k2<0) will be discussed in a succeeding letter],

Akira Hasegawa; Frederick Tappert

1973-01-01

159

Anomalous transmission of an ultrashort ionizing laser pulse through a thin foil.  

PubMed

The formation of a highly anisotropic photoelectron velocity distribution as a result of the interaction of a powerful ultrashort laser pulse with a thin foil is found to yield a large skin-layer depth and an anomalous increase of the transmission coefficient. The physical reason for the effect is the influence of the incident wave magnetic field, through the Lorenz force, on the electron kinetics in the skin layer. PMID:14525249

Ferrante, G; Zarcone, M; Uryupin, S A

2003-08-21

160

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,

M. Ponton; F. Ramirez; A. Suarez

2010-01-01

161

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

162

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

PubMed Central

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

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

2013-01-01

163

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

164

Beam-forming techniques with applications to pulsed Doppler ultrasonic flowmeters  

NASA Astrophysics Data System (ADS)

The near-field and array approaches to beam forming appear to be the most practical and useful methods for providing uniform illumination of the cross section of blood vessels. Through the near-field approach, the required beam patterns are produced in the near field of pulsed transducers and, as a result, it is most suitable for peripheral applications. Field patterns of pulsed transducers are defined and are investigated by theoretical analysis, numerical simulation, and experimental characterization to verify the validity and indicate the limitations of this approach. Transducers are designed and fabricated, based on these results, and are employed in the preliminary flowmeter system evaluation. The use of transducer arrays is the only viable approach to deepbody measurements and flexible beamwidth adjustment. A theory, founded on the finite Fourier-Bessel and Dini series expansions, is developed to synthesize circularly symmetrical beam patterns by means of concentric annular arrays. Its application to the generation of variable-width uniform beams results in a canonical design procedure. A prototype transducer array suitable for transcutaneous cardiac-output estimation was developed.

Fu, C. C.

165

Ultrasonic flow measurements for irrigation process monitoring  

NASA Astrophysics Data System (ADS)

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

Ziani, Elmostafa; Bennouna, Mustapha; Boissier, Raymond

2004-02-01

166

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

167

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

SciTech Connect

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

Nadeau, A.; Nadeau, F.; Choquet, M. [Tecnar Automation Ltd, Saint-Bruno, QC J3V6B5 (Canada); Martin, F. [Institut National de Recherche Scientifique, Varennes, QC J3X1S2 (Canada); Blouin, A.; Lord, M. [Industrial Matreials Institute, NRC, Boucherville, QC J4B6Y4 (Canada)

2007-03-21

168

Nonlinear transmission of ultrashort light pulses by a thin semiconductor film in the exciton range of the spectrum  

NASA Astrophysics Data System (ADS)

A study is reported of the influence of the saturation of the dipole momentum of an exciton transition on transient transmission of ultrashort laser pulses by a thin semiconductor film in the exciton range of spectrum. It is shown that when rectangular pulses of resonant laser radiation are incident on the film, a threshold-type qualitative change in the transmission by the film takes place from almost total reflection at low level of excitation to complete bleaching at high values of the incident pulse amplitude. An analog of the McCall-Hahn area theorem is derived for ultrashort pulses interacting with the film. When the nonlinear parameter is large, the dependence of the area of a pulse transmitted by the film on the area of an incident pulse becomes multivalued.

Khadzhi, P. I.; Gaivan, S. L.

1998-07-01

169

Analysis of pulsed-signal transmission in a system of interacting neural oscillators with frequency-dependent connections  

NASA Astrophysics Data System (ADS)

In this paper, we study the influence of the frequency-dependent connection on the signal transmission in a system of two interacting pulsed neural oscillators. The system is a model of two neurons with synaptic connection having the synaptic-plasticity feature, i.e., synaptic-parameter variation as a function of the frequency characteristics of the signal. It is shown that plastic connection can control the signal-transmission efficiency depending on the pulse-repetition rate and ensures stable synchronization modes of the pulse trains with different ratios between the frequencies of the output and input pulses. Analytical estimates for the parameter ranges corresponding to generation of the pulse response at the detector neuron depending on the pulse-repetition rate at the oscillator neuron were obtained.

Prokin, I. S.; Kazantsev, V. B.

2012-04-01

170

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

NASA Astrophysics Data System (ADS)

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 ? 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.

Burdt, R.; Curry, R. D.

2007-07-01

171

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

172

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

173

Geometric Limitations Of Ultrasonic Measurements  

NASA Astrophysics Data System (ADS)

Laboratory experiments are a key for interpreting seismic field observations. Due to their potential in many experimental set-ups, the determination of elastic properties of minerals and rocks by ultrasonic measurements is common in Geosciences. The quality and thus use of ultrasonic data, however, strongly depends on the sample geometry and wavelength of the sound wave. Two factors, the diameter-to-wavelength- ratio and the diameter-to-length-ratio, are believed to be the essential parameters to affect ultrasonic signal quality. In this study, we determined under well defined conditions the restricting dimensional parameters to test the validity of published assumptions. By the use of commercial ultrasonic transducers a number of experiments were conducted on aluminium, alumina, and acrylic glass rods of varying diameter (30-10 mm) and constant length. At each diameter compressional wave travel times were measured by pulse- transmission method. From the observed travel times ultrasonic wave velocities were calculated. One additional experiment was performed with a series of square-shaped aluminium blocks in order to investigate the effect of the geometry of the samples cross-sectional area. The experimental results show that the simple diameter-to-wavelength ratios are not valid even under idealized experimental conditions and more complex relation has to be talen into account. As diameter decreases the P-waves direct phase is increasingly interfered and weakened by sidewall reflections. At very small diameters compressional waves are replaced by bar waves and P-wave signals become non resolvable. Considering the suppression of both effects, a critical D/ë-ratio was determined and compared to experimental set-ups from various publications. These tests indicate that some published and cited data derived from small diameter set-ups are out off the range of physical possibility.

von Nicolai, C.; Schilling, F.

2006-12-01

174

A noniterative method to design large-tip-angle multidimensional spatially-selective radio frequency pulses for parallel transmission.  

PubMed

Recently, theoretical and experimental work has shown that parallel transmission of RF pulses can be used to shorten the duration of multidimensional spatially-selective pulses and compensate for B(1) field inhomogeneity. However, all the existing noniterative methods can design only excitation pulses for parallel transmission with a small flip angle (e.g., 30 degrees , or at most 90 degrees ) and cannot design large-tip-angle inversion/refocusing pulses, because these methods are based on the small-tip-angle (STA) approximation of the Bloch equation. In this work, a method to design large-tip-angle multidimensional spatially-selective pulses for parallel transmission is proposed, based on an extension of the single-channel linear-class large-tip-angle (LCLTA) theory. Design examples of 2D refocusing and inversion parallel transmit pulses and magnetization profiles from Bloch equation simulations demonstrate the strength of the proposed method. A 2D spin-echo parallel transmission experiment on a slab phantom using a 180 degrees refocusing pulse with an eight-channel transmit-only array further validates the effectiveness of the proposed method. PMID:17654576

Xu, Dan; King, Kevin F; Zhu, Yudong; McKinnon, Graeme C; Liang, Zhi-Pei

2007-08-01

175

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

176

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

177

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

178

Preliminary trial to investigate temperature of the iPulse™ intense pulsed light (IPL) glass transmission block during treatment of Fitzpatrick II, IV, V, and VI skin types  

Microsoft Academic Search

The glass transmission block, a key component of all intense pulsed light (IPL) devices, is responsible for the delivery of\\u000a IPL energy from the xenon discharge lamp to hair and skin structures during treatment. The purpose of this study was to investigate\\u000a the variation in temperature of the quartz glass block used in the iPulse™ (CyDen, Swansea, UK) handset during

C. Ash; G. A. Town; G. R. Martin

2007-01-01

179

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

Microsoft Academic Search

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

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

2004-01-01

180

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

SciTech Connect

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

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

1992-02-01

181

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

182

Timing jitter due to carrier linewidth of laser-diode pulse sources in ultra-high speed soliton transmission  

NASA Astrophysics Data System (ADS)

We theoretically analyze the timing jitter due to both the carrier phase noise of laser-diode (LD) pulse sources and the Gordon-Haus effect in soliton transmission. A formula is derived for the timing jitter in terms of the carrier linewidth, one of the measurable parameters common to all types of LD pulse sources. The transmission distance restricted by the timing jitter is analyzed, and the carrier linewidths required for ultra-long distance and ultra-high speed soliton transmission are estimated as well. Recirculating loop experiments at 10 Gb/s are demonstrated using two pulse sources; a gain-switched DFB-LD and a sinusoidally driven monolithically integrated MQW-DFB-LD/MQW-EA modulator, which have different carrier linewidths due to their different pulse formation processes. The difference in the carrier linewidths of the two pulse sources is measured by the proposed technique which is based on the optical heterodyne method. The observed difference between the two pulse sources in terms of timing jitter accumulation and timing jitter reduction with optical bandpass filters for the two pulse sources well support the theoretical predictions.

Iwatsuki, Katsumi; Kawai, Shingo; Nishi, Shigendo; Saruwatari, Masatoshi

1995-04-01

183

Ultrasonic properties of granular media saturated with dnapl\\/watermixtures  

Microsoft Academic Search

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

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

2007-01-01

184

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

Microsoft Academic Search

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

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

185

Adaptation of an air-dielectric RF cable for use as an oil-filled high voltage pulse transmission line  

Microsoft Academic Search

The specifications, conceptual design, prototype testing and operating experience of an oil-filled high voltage pulse transmission cable adapted from commercially available air-dielectric RF components are described. Lawrence Livermore National Laboratory's Advanced Test Accelerator (ATA) requires a method of transmitting 250kV, 70 nanosecond pulses from the power conditioning equipment to the accelerator. The oil-filled cable approach was chosen over alternative concepts

W. C. Weiss; R. L. Copp; L. L. Reginato; J. A. Schmidt

1984-01-01

186

Ultrasonic Diagnostic Instruments  

Microsoft Academic Search

The underlying physical principles and current limitations of diagnostic ultrasonic instruments are reviewed. Recently developed ultrasonic imaging devices using pulsed-reflected ultrasound are discussed in detail. These instruments transmit short trains of 1.5- to 10-megahertz sound. Echoes reflected from tissue are converted to electrical signals, which are presented on a display device to outline the contour of tissues and organs within

Richard L. Popp; Albert Macovski

1980-01-01

187

Modeling NDT piezoelectric ultrasonic transmitters.  

PubMed

Ultrasonic NDT applications are frequently based on the spike excitation of piezoelectric transducers by means of efficient pulsers which usually include a power switching device (e.g. SCR or MOS-FET) and some rectifier components. In this paper we present an approximate frequency domain electro-acoustic model for pulsed piezoelectric ultrasonic transmitters which, by integrating partial models of the different stages (driving electronics, tuning/matching networks and broadband piezoelectric transducer), allows the computation of the emission transfer function and output force temporal waveform. An approximate frequency domain model is used for the evaluation of the electrical driving pulse from the spike generator. Tuning circuits, interconnecting cable and mechanical impedance matching layers are modeled by means of transmission lines and the classical quadripole approach. The KLM model is used for the piezoelectric transducer. In addition, a PSPICE scheme is used for an alternative simulation of the broadband driving spike, including the accurate evaluation of non-linear driving effects. Several examples illustrate the capabilities of the specifically developed software. PMID:15047298

San Emeterio, J L; Ramos, A; Sanz, P T; Ruíz, A; Azbaid, A

2004-04-01

188

Outgassing of lower hybrid antenna modules during high-power long-pulse transmission  

NASA Astrophysics Data System (ADS)

During high-power, long-pulse transmission from lower-hybrid-range-of-frequency (LHRF) antennas, the waveguide walls outgas as a result of rf-loss-induced heating. If the resulting pressure rise is too high, power transmission will be adversely affected and additional pumping may be required to maintain the pressure at a low enough value. The outgassing rates of waveguides made of various materials (oxygen-free high-conductivity copper, dispersoid copper, copper-coated carbon fiber composite, copper-coated graphite) were measured during rf injection at high power density (50-200 MW/m2) for a duration in the range 100-4700 s. The experiments were performed on a test-bed facility equipped with a 3.7 GHz klystron on multiwaveguide (2 to 18) mock-ups. The effect of the main parameters, namely, the waveguide surface temperature and the initial wall gas loading (``conditioning''), are analyzed in detail. It is concluded that an outgassing rate of 1×10-5 (5×10-5) Pa m3 s-1 m-2 at 300 °C (400 °C) can be considered for most materials. The requirement, in terms of additional pumping, for the International Thermonuclear Experimental Reactor LHRF antenna is finally discussed.

Goniche, M.; Kazarian, F.; Bibet, P.; Maebara, S.; Seki, M.; Ikeda, Y.; Imai, T.

2005-01-01

189

Outgassing of lower hybrid antenna modules during high-power long-pulse transmission  

SciTech Connect

During high-power, long-pulse transmission from lower-hybrid-range-of-frequency (LHRF) antennas, the waveguide walls outgas as a result of rf-loss-induced heating. If the resulting pressure rise is too high, power transmission will be adversely affected and additional pumping may be required to maintain the pressure at a low enough value. The outgassing rates of waveguides made of various materials (oxygen-free high-conductivity copper, dispersoid copper, copper-coated carbon fiber composite, copper-coated graphite) were measured during rf injection at high power density (50-200 MW/m{sup 2}) for a duration in the range 100-4700 s. The experiments were performed on a test-bed facility equipped with a 3.7 GHz klystron on multiwaveguide (2 to 18) mock-ups. The effect of the main parameters, namely, the waveguide surface temperature and the initial wall gas loading ('conditioning'), are analyzed in detail. It is concluded that an outgassing rate of 1x10{sup -5} (5x10{sup -5}) Pa m{sup 3} s{sup -1} m{sup -2} at 300 deg. C (400 deg. C) can be considered for most materials. The requirement, in terms of additional pumping, for the International Thermonuclear Experimental Reactor LHRF antenna is finally discussed.

Goniche, M.; Kazarian, F.; Bibet, P.; Maebara, S.; Seki, M.; Ikeda, Y.; Imai, T. [Association EURATOM-CEA, CEA/DSM/DRFC, CEA-Cadarache, 13108 St Paul-Lez-Durance (France); Naka Fusion Research Establishment, Japan Atomic Energy Research Institute, Naka-machi, Naka-gun, Ibaraki-ken 311-0193 (Japan)

2005-01-01

190

Capacitively coupled transmission line pulsing CC-TLP – A traceable and reproducible stress method in the CDM-domain  

Microsoft Academic Search

This paper describes a new test method called Capacitively Coupled Transmission Line Pulsing cc-TLP. It is applied to different test circuits which were mounted on specially designed package emulators with a defined background capacitance. The test results are compared with the ESD thresholds obtained by CDM tests. The CC-TLP results correlate well with the CDM data.

Heinrich Wolf; Horst Gieser; Wolfgang Stadler; Wolfgang Wilkening

2003-01-01

191

Transient analysis of transmission lines loaded by active devices illuminated by an electromagnetic pulse in the indoor environment  

Microsoft Academic Search

A hybrid method, based on new FDTD (2, 4)-compatible conformal technique, telegraph equations and modified nodal analysis (MNA) method, is presented for transient analysis of a multi-conductor transmission line (MTL) network loaded with some active devices. The MTL network is located in a room with curved wall and is illuminated by an electromagnetic pulse (EMP). The accuracy of our developed

Jian Wang; Jin-Peng Fang; Wen-Yan Yin

2010-01-01

192

Does the ESD-failure current obtained by transmission-line pulsing always correlate to human body model tests?  

Microsoft Academic Search

Two different technologies serve as examples that the degree of correlation between ESD-failure currents obtained by transmission-line pulsing (TLP) and human body model (HBM) is a matter of the technology under investigation. Stressing a device with HBM or TLP can lead to different failure modes and, as a consequence, to a miscorrelation between the two test methods. Optimising a technology

W Stadler; X Guggenmos; P Egger; H Gieser; C Musshoff

1998-01-01

193

Determination of the inelastic properties of TiC-TiNi hard alloys by the ultrasonic pulsed method  

SciTech Connect

In the interest of finding an alloy with the properties of tungsten carbide in order to conserve the remaining reserves of tungsten, the authors ultrasonically test for the inelasticity of TiC-TiNi alloys as well as for the effect of boron on this property and the capacity of the alloy to absorb, damp or propagate ultrasonic waves. They find that the damping characteristics of the alloy may be characterized by the attenuation factor in the MHz range. The TiNi binding phase should have a high damping effect. The addition of boron results in a purer and denser alloy. The authors believe that the increase in the attenuation factor with an increase in boron content to 2% is associated with the increase in porosity rather than the damping capacity of the alloy.

Akimov, V.V.; Vil'msen, I.I.; Panin, V.E.; Kul'kov, S.N.

1986-12-01

194

Ultrasonic characterization of laser ablation.  

National Technical Information Service (NTIS)

When a pulsed laser beam strikes the surface of an absorbing material, ultrasonic waves are generated due to thermoelectric expansion and, at higher laser power densities, ablation of the material. These sound generation mechanisms have been the subject o...

J. A. Smith K. L. Telschow

1991-01-01

195

Adaptation of an air-dielectric RF cable for use as an oil-filled high voltage pulse transmission line  

NASA Astrophysics Data System (ADS)

The specifications, conceptual design, prototype testing and operating experience of an oil-filled high voltage pulse transmission cable adapted from commercially available air-dielectric RF components are described. Lawrence Livermore National Laboratory's Advanced Test Accelerator (ATA) requires a method of transmitting 250kV, 70 nanosecond pulses from the power conditioning equipment to the accelerator. The oil-filled cable approach was chosen over alternative concepts because of its high voltage holding capacity, long life and flexibility. The criteria for cable and connector design are discussed. The results of prototype testing and performance of the final design are presented.

Weiss, W. C.; Copp, R. L.; Reginato, L. L.; Schmidt, J. A.

1984-11-01

196

The Effect of Velocity Inhomogeneous, Lossy, and Refractive Media on the 3-D Propagation of Bounded Ultrasonic Pulses: Applications to Acoustical Imaging  

NASA Astrophysics Data System (ADS)

When a pulse propagates through a velocity and density inhomogeneous lossy medium, it scatters from the inhomogeneities, refracts as it advances with nonuniform speed through regions of varying velocity, and stretches as frequency dependent attenuation diminishes the higher frequencies. The commonly used Born series expansion equations obtained from the time dependent integral form of the inhomogeneous wave equation, sufficiently model the scattering but fail to model the nonuniform propagation and pulse stretching. We propose a new model which introduces the nonuniform wave propagation speed and frequency dependent attenuation into the Born series equations. The nonuniform wave propagation speed is approximated by modifying the free space Green's function contained within the Born series equations. The frequency dependent attenuation is then rigorously incorporated through the use of a time varying superposition integral. In practice, the model is implemented in two steps. First, the multiple scattering from the medium's inhomogeneities is evaluated under impulsive input conditions using the classical Born series equations to th order. Then in a post processing step, it is possible to add to this result the effects of the statistically averaged nonuniform wave propagation speed, and frequency dependent attenuation, by applying a time varying superposition integral filter. The equations describing this model are presented in detail. An example is given which demonstrates its application to study the ability of a typical ultrasonic imaging system to focus within an inhomogeneous medium.

Chandler, Paul Everett

197

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

PubMed Central

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

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

2010-01-01

198

Health monitoring of complex curved structures using an ultrasonic wavefield propagation imaging system  

Microsoft Academic Search

An ultrasonic wavefield propagation imaging system is introduced and then applied for ultrasonic wavefield imaging of complex curved surfaces. A Q-switched pulsed laser is utilized as a moving ultrasonic generator, and a PZT ultrasonic sensor is fixed during the laser beam scanning and detects the ultrasonic waves propagated from the points excited by the laser beam. The waveforms are allocated

Jung-Ryul Lee; Junji Takatsubo; Nobuyuki Toyama; Dong-Hoon Kang

2007-01-01

199

Ultrasonic Polishing.  

National Technical Information Service (NTIS)

The ultrasonic polishing process makes use of the high-frequency (ultrasonic) vibrations of an abradable tool which automatically conforms to the work piece and an abrasive slurry to finish surfaces and edges on complex, highly detailed, close tolerance c...

R. Gilmore

1993-01-01

200

Ultrasonic Flowmeters.  

National Technical Information Service (NTIS)

A prototype ultrasonic flowmeter was assembled and tested. The theoretical basis of this prototype ultrasonic flowmeter is reviewed; the equipment requirements for a portable unit are discussed; the individual electronic modules contained in the prototype...

W. D. Wittekind

1979-01-01

201

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

Microsoft Academic Search

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

Hu Peng

2007-01-01

202

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

203

Enhancing Power Transfer Capacity of Transmission System by a Reduced Magnetics Based 48Pulse STATCOM Controller  

Microsoft Academic Search

The static synchronous compensator (STATCOM) being the state-of-the-art voltage source converter (VSC) based dynamic shunt compensator in FACTS family (flexible alternating current transmission system) is increasingly employed in transmission system for reactive power control, increase of power transfer capacity, voltage regulation etc. Utilization of such controller at the middle location of the high voltage transmission system is focused in this

B. Singh; R. Saha

2008-01-01

204

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

SciTech Connect

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

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

2010-04-15

205

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

206

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

207

Ultrasonically assisted evaluation of the impact of atherosclerotic plaque on the pulse pressure wave propagation: A clinical feasibility study  

Microsoft Academic Search

The purpose of this work was to evaluate ultrasound modality as a non-invasive tool for determination of impact of the degree of the atherosclerotic plaque located in human internal carotid arteries on the values of the parameters of the pulse wave. Specifically, the applicability of the method to such arteries as brachial, common, and internal carotid was examined. The method

Z. Trawi?ski; L. Hilgertner; P. A. Lewin; A. Nowicki

208

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

PubMed

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

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

2013-01-01

209

Enhancing acoustic signal quality by rapidly switching between pulse-echo and through-transmission using diplexers  

NASA Astrophysics Data System (ADS)

The increase of terrorism and its global impact has made the screening of the contents of liquid-filled containers a necessity. The ability to evaluate the contents of a container rapidly and accurately is a critical tool in maintaining global safety and security. Due to the immense quantities and large variety of containers shipped worldwide, there is a need for a technology that enables rapid and effective ways of conducting non-intrusive container inspections. Such inspections can be performed utilizing "through-transmission" or "pulse-echo" acoustic techniques, in combination with multiple frequency excitation pulses or waveforms. The challenge is combining and switching between the different acoustic techniques without distorting the excitation pulse or waveform, degrading or adding noise to the receive signal; while maintaining a portable, low-power, low-cost, and easy to use system. The Pacific Northwest National Laboratory (PNNL) has developed a methodology and prototype device focused on this challenge. The prototype relies on an advanced diplexer circuit capable of rapidly switching between both "through-transmission" and "pulse-echo" detection modes. This type of detection requires the prototype to isolate the pulsing circuitry from the receiving circuitry to prevent damage and reduce noise. The results of this work demonstrate that an advanced diplexer circuit can be effective; however, some bandwidth issues exist. This paper focuses on laboratory measurements and test results acquired with the PNNL prototype device as applied to several types of liquid-filled containers. Results of work conducted in the laboratory will be presented and future measurement platform enhancements will be discussed.

Valencia, Juan D.; Diaz, Aaron A.; Tucker, Brian J.

2008-04-01

210

Fiber optic cables for transmission of high-power laser pulses  

Microsoft Academic Search

High power pulsed lasers are commonly deployed in harsh environments, like space flight and military missions, for a variety of systems such as LIDAR, optical communications over long distances, or optical firing of explosives. Fiber coupling of the laser pulse from the laser to where it is needed can often save size, reduce weight, and lead to a more robust

W. Joe Thomes Jr.; Melanie N. Ott; Richard F. Chuska; Robert C. Switzer; Diana E. Blair

2011-01-01

211

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

212

Ultrasonic properties of granular media saturated with DNAPL\\/water mixtures  

Microsoft Academic Search

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

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

2007-01-01

213

Ultrasonic properties of granular media saturated with DNAPL\\/water mixtures  

Microsoft Academic Search

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

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

2007-01-01

214

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

215

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

216

Laser–ultrasonic absorption measurements in low carbon steels  

Microsoft Academic Search

We have refined the contactless laser–ultrasound reverberation technique to measure ultrasonic absorption on small metallic samples. In this technique, a sample is supported by a holder which is ultrasonically decoupled from the sample. A pulsed laser is used to generate an acoustic pulse. After the pulse has mode converted and scattered sufficiently to fully insonify the sample, the decrease in

A Moreau; M Lord; D Lévesque; M Dubois; J. F Bussière

2000-01-01

217

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

218

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

2013-02-05

219

Transmission of bipolar video frequency electromagnetic pulses through a thin film of semiconductor with quantum superlattice  

NASA Astrophysics Data System (ADS)

The possibility of generating harmonics for passing electromagnetic pulses with t(p) of 10 exp -12 s through a thin film of a semiconductor with a quantum superlattice is explored. The generation of harmonics is seen to take place for q(0) of not less than 7 only. Assuming a superlattice period of 100 A, it is found that the electric field of incident video pulses should be not less than 2.5 kV/cm.

Vanagas, E.

1993-04-01

220

STEM (scanning transmission electron microscopy) analysis of femtosecond laser pulse induced damage to bulk silicon  

Microsoft Academic Search

This work reports on the structural changes that take place in wafer grade silicon when it is micro-machined with ultra-short laser pulses of 150 fs duration. A Chirped Pulse Amplification (CPA) Ti:Sapphire laser was used, with an operating wavelength centered on 775 nm and a maximum repetition rate of 1 KHz. The laser induced damage was characterized over the fluence range 0.43–14 J?cm-2, and

E. Coyne; J. P. Magee; P. Mannion; G. M. O’Connor; T. J. Glynn

2005-01-01

221

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

222

Experience with ultrasonic flowmeters  

SciTech Connect

Ultrasonic flowmeters have been around since the 1960s and were used for oceanographic and military applications before they were introduced to the process industries. There are several different kinds of ultrasonic flowmeters, but they all work on the principle of frequency shift due to velocity. The purpose of this article is to review experiences, both good and bad, with both Doppler and transit time ultrasonic flowmeters. The most common type of ultrasonic flowmeter is the Doppler meter. The Doppler meter signal is reflected by particles, bubbles, or other discontinuities in the liquid, and the frequency is shifted by velocity of these discontinuities. This frequency shift renders a signal proportional to velocity. Another common type of ultrasonic flowmeter is the ''time-of-flight'' or transit time meter. This meter uses two sensors that are lined up at an angle to the direction of flow, and that pulse alternately. A time-differential relationship proportional to the flow is calculated. In this case, the fluid must be free of entrainment or else scattering of the signal may induce an error.

DeVries, E.A.

1986-06-01

223

Ultrasonic Technology  

NASA Astrophysics Data System (ADS)

Ultrasonic has proven its merit as one of the most promising sensing methods for food quality evaluation due to its non-destructive, noninvasive, precise, rapid, and on-line potential. Ultrasonic is mechanical wave at frequencies above 20 kHz propagating by vibration of the particles in the medium and penetrating through optically opaque materials to provide internal or surface information of physical attributes, such as texture and structure. Ultrasonic non-destructive testing is a way of characterizing materials by transmitting ultrasonic waves into a material, and investigating the characteristics of the transmitted and/or reflected ultrasonic waves. For the purpose of quality measurement of materials, low-intensity ultrasonic with the power level of up to 1 W/cm2 has been used. The low-intensity ultrasonic doesn't cause physical or chemical changes in the properties of the specimen when it transmits through the material. However, high-intensity ultrasonic of the power range above 1 W/cm2 may produce physical/chemical disruption and alteration in the material through which the wave propagates. High-intensity ultrasonic is usually used in cleaning, promotion of chemical reactions, homogenization, etc

Cho, Byoung-Kwan

224

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

225

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

NASA Astrophysics Data System (ADS)

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

Shapiro, Jeffrey H.

2011-09-01

226

Ultrasonic liposculpturing  

Microsoft Academic Search

The author describes a revolutionary body contouring technique based on the surgical use of ultrasonic energy. It allows the selective destruction of only excess adipose tissue. The technique is based on three fundamental steps: (1) preparation of the areas to be treated with a large infiltration of a special solution, (2) treatment of the areas with ultrasonic energy through special

Michele Zocchi

1992-01-01

227

Ultrasonic Motor,  

National Technical Information Service (NTIS)

As electronics represented by computers make progress, comparable actuators of small size and high-speed response are in strong demand. This ultrasonic motor is based on an utterly new principle where the rotating force is obtained by an ultrasonic vibrat...

A. Tokushima N. Harao K. Takahashi N. Sugano R. Inaba

1987-01-01

228

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

229

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

230

Direct ultrasonic measurement of solid propellant ballistics  

Microsoft Academic Search

This article illustrates the application of an ultrasonic pulse-echo technique to determine the burning rate of a composite solid propellant as a function of pressure. An evaluation of the measurement uncertainty of the method is also presented. Unlike the more traditional strand burner techniques, where dozens of constant pressure tests are necessary, the ultrasonic technique measures the burn surface position

Roberto di Salvo; Frédéric Dauch; Robert A. Frederick; Marlow D. Moser

1999-01-01

231

Direct ultrasonic measurement of solid propellant ballistics  

Microsoft Academic Search

This article illustrates the application of an ultrasonic pulse–echo technique to determine the burning rate of a composite solid propellant as a function of pressure. An evaluation of the measurement uncertainty of the method is also presented. Unlike the more traditional strand burner techniques, where dozens of constant pressure tests are necessary, the ultrasonic technique measures the burn surface position

Roberto Di Salvo; Fre´de´ric Dauch; Robert A. Frederick; Marlow D. Moser

1999-01-01

232

Ultrasonic characterization of vegetable oil product.  

National Technical Information Service (NTIS)

The ultrasonic wave velocity and attenuation of a number vegetable oil products were measured using an ultrasonic pulse echo overlap technique from room temperature up to 90(sup 0)C. Among the liquid samples studied were refined bleach deodorized (RED) pa...

Sidek Hj Abd Aziz Chow Sai Pew Abdul Halim Shaari Nor Azizah Shaari

1992-01-01

233

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

National Technical Information Service (NTIS)

An apparatus and method for determination of sample thickness and surface depression utilizing ultrasonic pulses is discussed. The sample is held in a predetermined position by a support member having a reference surface. Ultrasonic pulses travel through ...

D. J. Roth

1996-01-01

234

Chemical vapor deposition diamond window for high-power and long pulse millimeter wave transmission  

Microsoft Academic Search

To satisfy the electrical and thermomechanical requirements for a continuous wave millimeter wave beam transmission, a window assembly using a large size synthesized diamond disk has been developed. Such window systems are needed as a vacuum barrier and tritium shielding in future electron cyclotron heating systems for fusion plasma heating and noninductive electron cyclotron current drive. The diamond used in

A. Kasugai; K. Sakamoto; K. Takahashi; M. Tsuneoka; T. Kariya; T. Imai; O. Braz; M. Thumm; J. R. Brandon; R. S. Sussman; A. Beale; D. C. Ballington

1998-01-01

235

Assessment of fibroblast cells submitted to ultrasonic irradiation.  

PubMed

Physiotherapists consider ultrasound an indispensable tool, which is commonly employed in clinical practice as a treatment aid for musculoskeletal dysfunctions. The aim of our study has been to analyze fibroblast cell structures following low-intensity pulsed ultrasonic irradiation. Fibroblast cell cultures irradiated with ultrasound were analyzed through electron microscopy to determine an ideal irradiation beam that preserved cell morphology and integrity. Analysis by fluorescence microscopy and transmission electron microscopy was used to follow morphological changes of the nucleus and cytoskeleton following different ultrasound irradiation intensities. According to the parameters used in the pulsed irradiation of fibroblast cultures, control over the intensity employed is fundamental to the optimal use of therapeutic ultrasound. Cell cultures submitted to low-intensity pulsed ultrasonic irradiation (0.2-0.6 W/cm2) at 10% (1:9 duty cycle) and 20% (2:8 duty cycle) maintained shape and cellular integrity, with little damage. In the group irradiated with an intensity of 0.8 W/cm2, a loss of adhesion was observed along with an alteration in the morphology of some cells at an intensity of 1.0 W/cm2, which resulted in the presence of cellular fragments and a decrease of adhering cells. In cells irradiated at 2.0 W/cm2, there was a complete loss of adhesion and aggregation of cellular fragments. The present study confirms that biophysical properties of pulsed ultrasound may accelerate proliferation processes in different biological tissues. PMID:18703155

de Oliveira, Rodrigo Franco; Pires Oliveira, Deise A A; Machado, Aline H A; da Silva, Newton Soares; Magini, Márcio; Pacheco-Soares, Cristina

2008-07-25

236

Ultrasonic modeling for complex geometries and materials  

NASA Astrophysics Data System (ADS)

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

Huang, Ruiju

237

A New Ultrasonic Flowmeter for Intravascular Application  

Microsoft Academic Search

An instrument for the measurement of pulsatile blood flow has been developed. The device uses a small probe suitable for intravascular insertion, and the method of measurement employs a combination of ultrasonic pulse techniques and phase detection.

K. G. Plass

1964-01-01

238

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

Microsoft Academic Search

We have used a well-known technique in wireless communication, pulse width modulation (PWM) of time division multiplexed (TDM) signals, within the architecture of a novel wireless integrated neural recording (WINeR) system. We have evaluated the performance of the PWM-based architecture and indicated its accuracy and potential sources of error through detailed theoretical analysis, simulations, and measurements on a setup consisting

Ming Yin; Maysam Ghovanloo

2009-01-01

239

Ultrasonic modeling for complex geometries and materials  

Microsoft Academic Search

This work considers ultrasonic wave propagation in complex geometries and materials and the scattering of various types of flaws. Multi-Gaussian beam models are developed where the wave field of an ultrasonic transducer is simulated by the superposition of a few Gaussian beams. It is shown that the propagation and transmission\\/reflection of a Gaussian beam in both isotropic and anisotropic media

Ruiju Huang

2006-01-01

240

Multi-slice parallel transmission three-dimensional tailored RF (PTX 3DTRF) pulse design for signal recovery in ultra high field functional MRI.  

PubMed

T(2)(?) weighted fMRI at high and ultra high field (UHF) is often hampered by susceptibility-induced, through-plane, signal loss. Three-dimensional tailored RF (3DTRF) pulses have been shown to be an effective approach for mitigating through-plane signal loss at UHF. However, the required RF pulse lengths are too long for practical applications. Recently, parallel transmission (PTX) has emerged as a very effective means for shortening the RF pulse duration for 3DTRF without sacrificing the excitation performance. In this article, we demonstrate a RF pulse design strategy for 3DTRF based on the use of multi-slice PTX 3DTRF to simultaneously and precisely recover signal with whole-brain coverage. Phantom and human experiments are used to demonstrate the effectiveness and robustness of the proposed method on three subjects using an eight-channel whole body parallel transmission system. PMID:23348046

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

2013-01-11

241

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

242

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

243

Subpicosecond pulse transmission over 144 km using midway optical phase conjugation via a cascaded second-order process in a LiNbO3 waveguide  

Microsoft Academic Search

We demonstrate for the first time the feasibility of 600-fs pulse transmission over 144 km using midway optical phase conjugation via a cascaded second-order process in a periodically poled LiNbO3 waveguide. The output pulses are negligibly distorted and broadened to 680 fs. This result could not be obtained without complete compensation for fourth-order dispersion performed by midway optical phase conjugation

D. Kunimatsu; C. Q. Xu; M. D. Pelusi; X. Wang; K. Kikuchi; H. Ito; A. Suzuki

2000-01-01

244

On-Chip Charged Device Model ESD Protection Design Method Using Very Fast Transmission Line Pulse System for RF ICs  

NASA Astrophysics Data System (ADS)

An on-chip Charged Device Model (CDM) ESD protection method for RF ICs is proposed in a 0.13µm RF process and evaluated by using very fast Transmission Line Pulse (vf-TLP) system. Key design parameters such as triggering voltage (Vt1) and the oxide breakdown voltage from the vf-TLP measurement are used to design input ESD protection circuits for a RF test chip. The characterization and the behavior of a Low Voltage Triggered Silicon Controlled Rectifier (SCR) which used for ESD protection clamp under vf-TLP measurements are also reported. The results measured by vf-TLP system showed that the triggering voltage decreased and the second breakdown current increased in comparison with the results measured by a standard 100ns TLP system. From the HBM/CDM testing, the RF test chip successfully met the requested RF ESD withstand level, HBM 1kV, MM 100V and CDM 500V.

Park, Jae-Young; Song, Jong-Kyu; Kim, Dae-Woo; Jang, Chang-Soo; Jung, Won-Young; Kim, Taek-Soo

245

512QAM Nyquist sinc-pulse transmission at 54 Gbit/s in an optical bandwidth of 3 GHz.  

PubMed

We demonstrate for the first time transmission of 54 Gbit/s and 48 Gbit/s over 44 km and 150 km, respectively, utilizing an optical bandwidth of only 3 GHz. We used polarization division multiplexed 512QAM and 256QAM modulation formats in combination with Nyquist pulse shaping having virtually zero roll-off. The resulting spectral efficiencies range up to 18 bit/s/Hz and 16 bit/s/Hz, respectively. Taking into account the overhead required for forward error correction, the occupied signal bandwidth corresponds to net spectral efficiencies of 14.4 bit/s/Hz and 15 bit/s/Hz, which could be achieved in a wavelength division multiplexed network without spectral guard bands. PMID:22418526

Schmogrow, R; Hillerkuss, D; Wolf, S; Bäuerle, B; Winter, M; Kleinow, P; Nebendahl, B; Dippon, T; Schindler, P C; Koos, C; Freude, W; Leuthold, J

2012-03-12

246

Ultrasonic Wave Generation by Lasers on Different Metal Surfaces  

SciTech Connect

Ultrasonic wave generation by short pulsed laser is revisited in this paper with new experimental work. The generation laser pulse is fiber delivered and a virtually uniform intensity spot is obtained. Ultrasonic pulse strength versus laser pulse energy is obtained for various aluminum and steel surface conditions. To have a better reproducibility, the sample moves after each measurement in order to have a fresh surface for each laser shot. Results show a strong effect of the surface condition. Special attention is paid to the frequency dependence of the generated ultrasonic waves for different laser intensities. The problem of the optimum spot size for a given laser pulse energy is also discussed.

Kruger, S. E.; Lord, M. [Industrial Materials Institute, National Research Council of Canada, Boucherville, Quebec, J4B 6Y4 (Canada)

2007-03-21

247

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

Microsoft Academic Search

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

B. Koehler; G. Hentges; W. Mueller

1998-01-01

248

Ultrasonic Motors.  

National Technical Information Service (NTIS)

Ultrasonic motors, which have superior characteristics like high torque at low speed, absence of magnetic interference, and compactness in size, are good candidates for medical applications, automation, robotics, aerospace engineering and various other fi...

S. Cagatay K. Uchino B. Koc

2003-01-01

249

Ultrasonic surgery.  

PubMed Central

Animal and clinical studies of a new approach in general surgery using an ultrasonic aspiration device have been encouraging. On 31 patients 11 liver procedures, 12 extensive head and neck dissections, 5 ultrasonic fulgurations for rectal cancer, and excision of 2 local oral lesions, 1 para-aortic mass, 1 pancreatic cancer, 1 giant subfascial lipoma, and 1 rectal villous adenoma have been carried out. Images FIg. 1 FIG. 2

Hodgson, W. J.

1980-01-01

250

Ultrasonic surgery.  

PubMed

Animal and clinical studies of a new approach in general surgery using an ultrasonic aspiration device have been encouraging. On 31 patients 11 liver procedures, 12 extensive head and neck dissections, 5 ultrasonic fulgurations for rectal cancer, and excision of 2 local oral lesions, 1 para-aortic mass, 1 pancreatic cancer, 1 giant subfascial lipoma, and 1 rectal villous adenoma have been carried out. PMID:7436305

Hodgson, W J

1980-11-01

251

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

252

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

NASA Astrophysics Data System (ADS)

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

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

2009-06-01

253

An ultrasonic sensor for distance measurement in automotive applications  

Microsoft Academic Search

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

Alessio Carullo; Marco Parvis

2001-01-01

254

Surfaces and thin films studied by picosecond ultrasonics  

SciTech Connect

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

Maris, J.H.; Tauc, J.

1992-05-01

255

System and technique for ultrasonic determination of degree of cooking  

DOEpatents

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

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

2007-03-20

256

Transmission line pulse test methods, test techniques and characterization of low capacitance voltage suppression device for system level electrostatic discharge compliance  

Microsoft Academic Search

Voltage suppression devices are needed in electronic systems to prevent damage to electrical components from electrical overstress (EOS) and electrostatic discharge (ESD) events. A low capacitance, polymer voltage-suppressor (PVS) device is evaluated using various testing techniques that combine transmission line pulse (TLP) test system, direct discharge HBM, and a system-level ESD gun. Additionally, test methods for integrating PVS devices for

Karen Shrier; Tuyen Truong; Jimmie Felps

2004-01-01

257

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

PubMed Central

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

Yin, Ming; Ghovanloo, Maysam

2013-01-01

258

a Data-Driven Correction of Ultrasonic Source and Receiver Spectral Amplitude Variations  

NASA Astrophysics Data System (ADS)

The application of phased arrays in NDT applications is growing. State of the art ultrasonic arrays consist of many small piezo-electric elements that can be excited separately to synthesize a desired wave front. This may vary from simple plane waves to complex-shaped focusing wave fields. An implicit requirement is that the source strength (sensitivity) of all elements is equal, to prevent artifacts in the generated wave front. The same holds for the detection of ultrasonic waves. In typical commercial ultrasonic arrays, however, sensitivity variations can be significant: amplitude variations of +/-3 dB are not uncommon. Pulse-echo data can be used for calibration of element strengths. The application of pulse-echo data, however, has some limitations: its performance may deteriorate when sensing irregularly-shaped media and the application is limited to cases with identical element sensitivity in transmission and detection. For ultrasonic measurements this is not necessarily true when separate transmit and receiver arrays are used, but is also not evident when the same array is used. A new data-driven method is demonstrated that can be used to determine the frequency-dependent sensitivity of each element in a phased array in emission and detection separately.

van Capel, P. J. S.; van Vossen, R.; Volker, A. W. F.

2011-06-01

259

Characterization of Periodic or Quasi Periodic Rough Surfaces by Ultrasonic Spectroscopy.  

National Technical Information Service (NTIS)

The scattering of wide-band ultrasonic pulses from rough surfaces is investigated with an ultrasonic spectroscopy technique. The spectral content of the echo is correlated to the quality of the surface. Some periodic defects can be distinguished from rand...

F. Cohen Tenoudji M. Joveniaux A. Jungman G. Quentin

1976-01-01

260

High-frequency ultrasonic cleaning tank utilizing oblique incidence  

Microsoft Academic Search

Transmission characteristics of a double-structured tank, used for high-frequency (1 MHz range) ultrasonic cleaning of semiconductor wafers and substrates, were improved by utilizing oblique incidence of ultrasonic waves. As the sound transmittivity through a plate in water varies with the angle of incidence, the bottom of the Pyrex glass inner container was slanted at the angle where strong transmission occurred.

Hajime Hatano; Sadao Kanai

1996-01-01

261

Transmission electron microscopy investigation of crystalline silicon surface irradiated by femtosecond laser pulses in different background atmospheres  

NASA Astrophysics Data System (ADS)

This article aims to obtain structural and compositional characteristics of a crystalline silicon surface irradiated by femtosecond laser pulses in SF6, N2, air, and vacuum background atmospheres by performing transmission electron microscopy observation of <110> cross-sectional specimens. Conical microstructures covered with defective outer layers were formed in SF6 gas. The elemental sulfur dopants in the surface microstructure, which located in close proximity to defects, were mainly concentrated at the tip region of the microcones, and about several hundred nanometers thick. In N2 atmosphere, the defects produced regularly on the silicon surface were of the same types with those formed in SF6 gas and confirmed to be stacking faults and overlapped twins. Furthermore, silicon crystalline grains with different orientations were observed on the silicon surface irradiated in N2, air, and vacuum atmospheres. Especially, ?-Si3N4 crystalline grains were found to be formed in N2 and air as chemical products when elemental nitrogen exists, and the SiO2 amorphous phase was formed in air by the oxidation effect. Based on these experimental results, the relevant interaction mechanisms between pulsed laser and crystalline silicon were suggested to be mainly attributed to laser-assisted chemical etching and laser ablation, i.e., if volatile silicon compounds can be produced in a reactive gas atmosphere (e.g., SF6), the strong laser-assisted chemical etching dominates over the laser irradiation process. Otherwise, laser ablation is the dominant mechanism such as in N2, air, and vacuum.

Wen, C.; Yang, H. D.; Li, X. H.; Cui, Y. X.; He, X. Q.; Duan, X. F.; Li, Z. H.

2012-11-01

262

Ultrasonic polishing  

NASA Astrophysics Data System (ADS)

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

Gilmore, Randy

1993-02-01

263

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

264

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

265

Ultrasonic motors  

Microsoft Academic Search

An ultrasonic motor is proposed which uses two piezoelectric elements in the stator. One element is used to generate a vibration polarized with respect to the direction of motion of the rotor or the slider. The other one generates a vibration perpendicular to the motion of the rotor. By imaging the ratio of the vibration amplitudes and the phase, the

S. Ueha; M. Kurosawa

1988-01-01

266

Ultrasonic through-transmission method of evaluating the modulus of elasticity of Al2O3–ZrO2 composite  

Microsoft Academic Search

The elastic properties of Al2O3–ZrO2 composite were determined from ultrasonic velocity measurements, and were found to be\\u000a dependent upon the amount of ZrO2 phase, the compacting pressure of the green ceramic and sintering time. The velocity in\\u000a the Al2O3–ZrO2 composite increased to a maximum for about 3 wt% unstabilized ZrO2 dispersed in Al2O3. The velocity decreased\\u000a monotonically thereafter. The increase

Tan. Kha. Shen; P. Hing

1997-01-01

267

Piezoelectric films for 100MHz ultrasonic transducers  

Microsoft Academic Search

Piezoelectric aluminum nitride (AlN) and zinc oxide (ZnO) thin films were deposited by reactive magnetron sputtering for use in ultrasonic transducers in the 100- to 300-MHz regime. Pulse-echo ultrasonic transducers are being developed to image subsurface microstructure in metal and non-metal (ceramic) materials and components. A Krimholtz, Leedom, Matthaei (KLM) model was used to aid in the design of the

Peter M. Martin; Morris S. Good; John W. Johnston; Gerald J. Posakony; Leonard J. Bond; Susan L. Crawford

2000-01-01

268

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

NASA Astrophysics Data System (ADS)

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

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

2004-07-01

269

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

270

Ultrasonic velocity measurements for estimation of grain size in austenitic stainless steel  

Microsoft Academic Search

Ultrasonic velocity measurements have been used to estimate average grain size in an AISI type 316 stainless steel. For precise ultrasonic transit time measurements, the pulse-echo-overlap technique has been used. Master graphs relating ultrasonic velocity with metallographically obtained grain size have been generated. Using these graphs, grain sizes in new specimen have been obtained. The results indicate that grain size

P. Palanichamy; A. Joseph; T. Jayakumar; Baldev Raj

1995-01-01

271

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

272

Nanocrystalline alpha-Ni(OH)2 prepared by ultrasonic precipitation.  

PubMed

Nanocrystalline alpha-Ni(OH)2 was prepared by an ultrasonic precipitation/stirring method. Results of X-ray diffraction, transmission electron microscopy, infrared, and thermogravimetric measurements confirm that the sample obtained is alpha phase. Compared with the sample prepared without ultrasonic stirring, the crystal structure of the alpha phase sample has been changed from beta phase. The crystalline size of the sample is about 20 nm, which is smaller than the sample produced without ultrasonic stirring (70 nm). PMID:12908319

Xia, X; Shen, L L; Guo, Z P; Liu, H K; Walter, G

2002-02-01

273

Measuring concentrations of electrolytes by a differential ultrasonic instrument  

Microsoft Academic Search

The measurement and automatic control of electrolyte concentrations is extremely important for the automation of various technological processes in the chemical industry. The ultrasonic method of measuring electrolyte concentrations is highly accurate and has no perturbing effect on the medium under investigation, due to the small intensity of the ultrasonic pulse radiations (of the order of hundredths of a w\\/cm2);

V. A. Nosov; S. K. Barashkov; M. A. Dyachenko; A. P. Sosenko

1962-01-01

274

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

275

Analysis of Ultrasonic Correlation Flowmeters for Pulp Suspension  

Microsoft Academic Search

Abstraet-A transit time flow measurement system using ultrasonics and cross correlation is studied and constructed for use in the pulp and paper industry. The primary signals are produced by the modulation action of suspension particles on the intensity of two ultrasonic beams. Both continuous and pulsed intensities are used. The signals may be received either as attenuated beams penetrating the

JOUNI S. TORNBERG; MATTI KARRAS; EINO M. HARKONEN; O. Hirsimaki

1983-01-01

276

Modeling Angle Beam Ultrasonic Testing Using Multi-Gaussian Beams  

Microsoft Academic Search

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

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

2004-01-01

277

Quantitative measurement of portal blood flow in patients with chronic liver disease using an ultrasonic duplex system consisting of a pulsed doppler flowmeter and B-mode electroscanner  

Microsoft Academic Search

Summary  Portal blood flow (PBF) can be measured quantitatively using a B-mode combined pulsed Doppler (BCD) system. This system combines\\u000a a real time B-mode linear type electroscanner and a pulsed Doppler (D-mode) flowmeter. Since both modes are displayed in realtime,\\u000a Dopper blood flow signals can be retrieved at will from any depth. The blood flow velocity determined by the Doppler spectrogram

Fuminori Moriyasu; Nobuyuki Ban; Osamu Nishida; Takefumi Nakamura; Shunzo Koizumi; Masahiko Sakai; Yuzo Kanematsu; Takeo Miyake; Haruto Uchino

1984-01-01

278

Ultrasonic Imaging  

NASA Astrophysics Data System (ADS)

Ultrasonic medical imaging provides a low cost and non-invasive tool to look inside the human body. It is one of the most popular imaging tools, second only to conventional X-ray imaging in the number of clinical procedures performed. It has various advantages over conventional X-ray, computed tomography and magnetic resonance imaging, because it does not utilise harmful electromagnetic radiation, is non-invasive, easy to perform, cost effective, capable of providing images in real time, and provides good soft tissue differentiation [1].

Wersing, W.; Lerch, R.

279

Ultrasonic Interferometers Revisited  

ERIC Educational Resources Information Center

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

Greenslade, Thomas B., Jr.

2007-01-01

280

Modern ultrasonic flowmeters  

NASA Astrophysics Data System (ADS)

The current status of ultrasonic flowmeters were reviewed on the basis of materials published in the Soviet Union and elsewhere. The following advantages of ultrasonic flowmeters over earlier instruments are cited. A comparative analysis is made of the design methods employed in ultrasonic flowmeters. The evolution of ultrasonic flowmetering is traced from the first generation and trends in their development are analyzed.

Gurevich, V. M.; Truman, S. G.

1986-01-01

281

Ultrasonic Interferometers Revisited  

ERIC Educational Resources Information Center

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

Greenslade, Thomas B., Jr.

2007-01-01

282

Acute differential modulation of synaptic transmission and cell survival during exposure to pulsed and continuous radiofrequency energy  

Microsoft Academic Search

Pulsed radiofrequency, in which short bursts of radiofrequency energy are applied to nervous tissue, has been recently described as an alternative technique devoid of nerve injury, a subsequent side effect of thermal lesions created by continuous radiofrequency lesioning. Yet the mechanism of this effect remains unclear. In this study we compared the acute effects of pulsed versus continuous radiofrequency energy

Alex Cahana; Laszlo Vutskits; Dominique Muller

2003-01-01

283

Wide-Band Ultrasonic Transducers: Design, Calibration, Radiation Intensity Measurement.  

National Technical Information Service (NTIS)

Transducers for ultrasonic testing reproduce short pulses. The band-pass is conditioned by natural frequencies. Calibration allows to find response, pressure, intensity and beam shape. Two methods are used to reach 10 MHz. (Atomindex citation 08:310895)

J. L. Garnier C. Gazanhes

1976-01-01

284

Ultrasonic Studies of Diffusion Controlled Ionic Association-Dissociation.  

National Technical Information Service (NTIS)

Ultrasonic absorption measurements have been made in solutions of copper sulfate, magnesium sulfate, and cobalt sulfate over the frequency range 45 to 550 MHz using pulse modulated waves and a send-receive technique. The excess relaxational absorption dat...

L. Goldfarb E. Yeager

1968-01-01

285

Thermogravimetric analysis of single-wall carbon nanotubes ultrasonicated in monochlorobenzene  

Microsoft Academic Search

The single-wall carbon nanotubes (SWNTs) purified by nitric acid were ultrasonicated in monochlorobenzene solution. Thermogravimetric analysis complemented by transmission electron microscopy and Raman spectroscopy was used to analyze the thus ultrasonicated SWNTs. The results show that two kinds of modified SWNTs and one modification-free SWNT coexist in ultrasonicated SWNTs and burned in three different temperature ranges. The different chemical modifications

Minfang Zhang; Masako Yudasaka; Akira Koshio; Sumio Iijima

2002-01-01

286

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

Microsoft Academic Search

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

Xianfeng Fan; Ming J. Zuo; Xiaodong Wang

2006-01-01

287

Absolute calibration technique for broadband ultrasonic transducers  

NASA Astrophysics Data System (ADS)

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.; Cantrell, John H.

1993-08-01

288

Absolute calibration technique for broadband ultrasonic transducers  

NASA Astrophysics Data System (ADS)

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.; Cantrell, John H.

1994-06-01

289

Investigation on ultrasonic and elastic properties of nano-structured silver by laser ultrasonic method  

Microsoft Academic Search

The ultrasonic velocities of longitudinal and transverse waves propagating in nano-structured silvers (here after nmAg) are measured by Laser ultrasonic technique. The samples of nmAg are composed of super fine particles with size of 20 to 100 nano-meter (nm). They are prepared by using physical method. An Nd:YAG Q-switched laser with duration 8 ns and adjustable pulse energy from 1

X. R. Zhang; X. Y. Qin; G. S. Cheng; L. D. Zhang

1996-01-01

290

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

291

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

292

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

293

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

294

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

295

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

296

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

PubMed

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

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

2012-07-21

297

Federal technology alert: Ultrasonic humidifiers  

SciTech Connect

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

NONE

1998-11-01

298

Fiberized laser ultrasonic source for process monitoring and biomedical applications  

NASA Astrophysics Data System (ADS)

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

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

2000-08-01

299

Computer simulation of ultrasonic testing for aerospace vehicle  

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

300

Effect of bending on ultrasonic preload measurements in bolts  

NASA Astrophysics Data System (ADS)

An ultrasonic pulse/echo technique is used to measure tensile preload on the umbilical flange joint bolts of the space shuttle orbiter. The ultrasonic instrument measures the round trip pulse travel time through the length of bolt. The pulse travel time increases with the applied load. The umbilical bolts experience bending loads in addition to the tensile load. The bending load affects the preload readings. The paper provides simplified theoretical derivations to explain the effect of bending on ultrasonic measurements. The bending loads cause rotation and translation of the ultrasonic pulse reflecting face. The bending also causes stress gradient in bolts. These effects cause phase gradient and physical shift in the received ultrasonic beam across the face of transducer, distorting the ultrasonic signal and introducing errors in the preload readings. A number of experiments were performed on the bolt to study the effect of bending combined with variation in transducers, bolt end designs and configurations. The bolt end design of the operational bolts was modified to reduce error in the readings. The paper provides explanation of the effect of bending in ultrasonic preload measurements and suggests approaches to minimize their effect.

Koshti, Ajay M.

2001-07-01

301

Investigation of intracranial media ultrasonic monitoring model  

Microsoft Academic Search

The objectives are to investigate the peculiarities of the ultrasound pulse propagation through human extra\\/intracranial media by mathematical simulation and to confirm the simulation results experimentally by proving the suitability of the ultrasonic time-of-flight measurement method for human intracranial media (IM) physiological non-invasive monitoring. The mathematical model of ultrasound pulse propagation through the human extra\\/intracranial media is described. The simulation

Vytautas Petkus; Arminas Ragauskas; Rytis Jurkonis

2002-01-01

302

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

303

An ultrasonic phased array system for NDT of steel structures  

NASA Astrophysics Data System (ADS)

A phased array ultrasonic inspection system is being developed ot obtain electronically scanned ultrasonic images of the inside of steel structures for nondestructive evaluation. This phased array ultrasonic inspection system is made up of computer, scanner, motion controller, motor driver, ultrasonic emission, receiving & delay circuit, high speed data acquisition circuit and ultrasonic phased array transducer, this system has the functions of controlling ultrasonic transmission and receiving, controlling sound wave steering and focusing, controlling scanner moving, revceiving position information and flaw information, restructuring flaw image. Experimental tests were done on a steel testing block with side-drilled holes to simulate defects. The side-drilled holes could be detected and their diameters could be estimated from B-scan image, and B-scan image could show the location of side drilled holes clearly and does not have any ghost image.

Shan, Baohua; Ou, Jinping

2005-06-01

304

Production of aqueous spherical gold nanoparticles using conventional ultrasonic bath  

NASA Astrophysics Data System (ADS)

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.

Lee, Ji-Hwan; Choi, Stephen U. S.; Jang, Seok Pil; Lee, Seoung Youn

2012-07-01

305

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

SciTech Connect

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

Maris, J.H.; Tauc, J.

1992-05-01

306

Ultrasonic Bone Densitometer.  

National Technical Information Service (NTIS)

A pair of opposed spaced ultrasonic transducers are held within a clamping apparatus closely adjacent the bone being analyzed. These ultrasonic transducers include piezoelectric crystals shaped to direct signals through the bone encompassed in the heel an...

J. M. Hoop

1973-01-01

307

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

308

Micro Piezoelectric Ultrasonic Motors.  

National Technical Information Service (NTIS)

This paper reviews recent developments of micro ultrasonic rotary motors using piezoelectric resonant vibrations. Following the historical background, four ultrasonic motors recently developed at Penn State University are introduced: windmill, PZT tube, m...

K. Uchino S. Cagatay B. Koc S. Dong P. Bouchilloux

2003-01-01

309

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

310

Flexible piezopolymer ultrasonic guided wave arrays  

Microsoft Academic Search

Ultrasonic guided wave technology is being applied to a variety of gas and liquid transmission pipeline inspection applications. There are a variety of promising transduction techniques used to excite longitudinal, torsional, and flexural modes in pipe. Some of the more common methods include electromagnetic-acoustic, magnetostrictive, and piezoceramic array transducers. The objective of the work presented in this paper was to

Thomas R. Hay; Joseph L. Rose

2006-01-01

311

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

312

Compact ultrasonic drier  

Microsoft Academic Search

The device for ultrasonic drying having improved technical specifications obtained due to drying chamber of special form is described in the article. The results of experiments showed that ultrasonic drier has maximum efficiency during the drying of capillary-porous materials. It was found out that the maximum efficiency can be achieved with ultrasonic exposure together with supply of heated (no more

V. N. Khmelev; Kwang Moon Choo; A. V. Shalunov; A. N. Lebedev; R. V. Barsukov; S. N. Tsyganok; K. V. Shalunova

2009-01-01

313

The effect of antenna and pulse waveform on ultra wide band link budget with impulse radio transmission  

Microsoft Academic Search

Abslmcf-In this paper, a link budget calculation for the Ultra Wide Band Impulse Radio (UWB-IR) transmission is evaluated. The novel link budget expression is derived and the impact of the antenna gain as well as the waveform of the generator ootput on the received voltage is investigated. UWB time domain measurements were performed to validate the link budget model. Results

Z. Irahhauten; A. Yarovoy; H. Nikookar; G. J. M. Janssen; L. P. Ligthart

2004-01-01

314

Optical piezoelectric transducer for nano-ultrasonics.  

PubMed

Piezoelectric semiconductor strained layers can be treated as piezoelectric transducers to generate nanometer-wavelength and THz-frequency acoustic waves. The mechanism of nano-acoustic wave (NAW) generation in strained piezoelectric layers, induced by femtosecond optical pulses, can be modeled by a macroscopic elastic continuum theory. The optical absorption change of the strained layers modulated by NAW through quantum-confined Franz-Keldysh (QCFK) effects allows optical detection of the propagating NAW. Based on these piezoelectric-based optical principles, we have designed an optical piezoelectric transducer (OPT) to generate NAW. The optically generated NAW is then applied to one-dimensional (1-D) ultrasonic scan for thickness measurement, which is the first step toward multidimensional nano-ultrasonic imaging. By launching a NAW pulse and resolving the returned acoustic echo signal with femtosecond optical pulses, the thickness of the studied layer can be measured with <1 nm resolution. This nano-structured OPT technique will provide the key toward the realization of nano-ultrasonics, which is analogous to the typical ultrasonic techniques but in a nanometer scale. PMID:16245610

Lin, Kung-Hsuan; Chern, Gia-Wei; Yu, Cheng-Ta; Liu, Tzu-Ming; Pan, Chang-Chi; Chen, Guan-Ting; Chyi, Jen-Inn; Huang, Sheng-Wen; Li, Pai-Chi; Sun, Chi-Kuang

2005-08-01

315

Ultrasonic flowmeter for gases. Final report  

SciTech Connect

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 instrument are discussed. The viability of a unique metering technique using reflected acoustic pulses was experimentally demonstrated. The flowmeter developed herein requires access to one side of the gas line and is self calibrating. It was concluded that continued development will produce a unit suitable for use in commercial service.

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

1984-10-01

316

Study of the compact fiber optic photoacoustic ultrasonic transducer  

NASA Astrophysics Data System (ADS)

Recently, many studies have been exerted on developing ultrasonic transducers that can feature high frequencies for better resolutions and compact sizes for the limit space nondestructive testing applications. Conventional ultrasonic transducers, which are made by piezoelectric materials, suffer from issues such as low frequencies and bulky sizes due to the difficulty of dicing piezoelectric materials into smaller pieces. On the other hand, generating ultrasonic signals by photoacoustic principle is a promising way to generate a high frequency ultrasonic pulse. Optical fiber is a very compact material that can carry the light energy. By combining the photoacoustic principle and the optical fiber together, a novel ultrasonic transducer that features a high frequency and a compact size could be achieved. In this paper, an ultrasonic transducer using gold nanoparticles as the photoacoustic generation material is described. Gold nanoparticles are deposited on the end surface of an optical fiber acting as the ultrasonic generator. A cavity and a diaphragm are fabricated in the center of the fiber using as the ultrasonic receiver. A phase array technique is applied to the transducer to steer the direction of the acoustic beam. Simulation results demonstrated that the photoacoustic ultrasonic transducer is feasible.

Wu, Nan; Tian, Ye; Zou, Xiaotian; Wang, Xingwei

2012-03-01

317

Diffraction effects on bulk-wave ultrasonic velocity and attenuation measurements  

PubMed

The loss and phase advance due to diffraction are experimentally observed by measuring the amplitude and phase of radio frequency (rf) tone burst signals in the VHF range, in an ultrasonic transmission line consisting of a buffer rod with an ultrasonic transducer on one end, a couplant of water, and a solid specimen of synthetic silica glass. The measured results agree well with the calculated results from the exact integral expression of diffraction. The diffraction effects on the velocity and attenuation measured in this frequency range and their corrections are investigated to realize more accurate measurements. It is shown that attenuation measurements are influenced by diffraction losses and can be corrected by numerical calculations, and that velocity measurements are affected by the phase advance caused by diffraction. This investigation demonstrates that, in complex-mode velocity measurements, in which the velocity is determined from the measured phase of the signals, the true velocity at each frequency can be obtained by correction using the numerical calculation of diffraction. Based on this result, a new correction method in amplitude-mode velocity measurements is also proposed. In this new method, the velocity is determined from the intervals of interference output obtained by sweeping the ultrasonic frequency for the superposed signals generated by the double-pulse method. Velocity may be measured accurately at frequencies in the Fresnel region, and diffraction correction is essential to obtain highly accurate values with five significant figures or more. PMID:10955621

Kushibiki; Arakawa

2000-08-01

318

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

319

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

320

Modelling for characterizing defects in plates using two-dimensional maps of instantaneous ultrasonic out-of-plane displacement obtained by pulsed TV-holography  

NASA Astrophysics Data System (ADS)

It has been demonstrated that non-destructive inspection of plates can be performed by using two-dimensional maps of instantaneous out-of-plane displacements obtained with a self-developed pulsed TV-holography system. Specifically, the interaction of guided elastic waves with defects produces scattering patterns that contain information about the defects (position, dimensions, orientation, etc.). For quantitative characterization on this basis, modeling of the wave propagation and interaction with the defects is necessary. In fact, the development of models for scattering of waves in plates is yet an active research field in which the most reliable approach is usually based on the rigorous formulation of elasticity theory. By contrast, in this work the capability of a simple two-dimensional scalar model for obtaining a quantitative description of the output two-dimensional maps associated to artificial defects in plates is studied. Some experiments recording the interaction of narrowband Rayleigh waves with artificial defects in aluminum plates are presented, in which the acoustic field is obtained from the TV-holography optical phase-change maps by means of a specially developed two-step spatio-temporal Fourier transform method. For the modeling, harmonic regime and free-stress boundary conditions are assumed. Comparisons between experimental and simulated maps are included for defects with different shapes.

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

2009-06-01

321

Experimental study on spray characteristics of ultrasonic atomizer  

NASA Astrophysics Data System (ADS)

An experimental study on the spray characteristics of an ultrasonic atomizer by utilizing a pulse laser holographic system is presented in this paper. The spatial distribution of the ultrasonic frequency and the pressure amplitude behind the atomizer are measured. It is shown by experiment that the sonic wave from the outlet of the atomizer travels as a spherical wave. The effects of the air pressure within the ultrasonic atomizer on the ultrasonic frequency and the pressure amplitude are studied. The effect of air pressure and fuel flow rate on the spatial distribution of the droplets and the SMD of fuel spray are obtained. Based on experimental results, the atomization mechanism of the ultrasonic atomizer is discussed.

Zhou, Xudong; Wang, Jiahua

1991-10-01

322

Ultrasonic wave propagation in temperature gradients  

SciTech Connect

Ultrasonic methods are being developed for sensing and control of high temperature material processes such as welding and solidification. One of the problems in these methods is the distortion of the sound field caused by the change in material properties due to temperature gradients. This paper describes a ray-tracing method for calculating the effects of temperature on ultrasonic propagation in such systems. In the ray-tracing method, the material is conceptually divided into a number of plane layers. The fraction at each layer boundary is calculated from Snell's law using the sound speeds determined from the temperatures of the adjacent layers. The time required for an ultrasonic pulse to traverse each layer is also calculated, allowing the determination of the total time along a particular path. The method is applied to calculating the time of arrival of echoes from various interfaces around a molten weld pool.

Johnson, J.A.; Carlson, N.M.; Lott, L.A.

1987-09-01

323

Continuous Secondary Ultrasonic Electropolishing of an SKD61 Cylindrical Part  

Microsoft Academic Search

An effective ultrasonic-aided electropolishing system using low-cost electrodes for polishing cylindrical parts is developed.\\u000a The process can be integrated with the primary processes of traditional turning, drawing, form rolling, or extrusion to achieve\\u000a a good surface finish for moulds. Ultrasonic energy is applied to the electrolyte for residue discharge during electropolishing.\\u000a Both continuous and pulsed direct current are tested in

P. S. Pa; H. Hocheng

2003-01-01

324

Measurement of intergranular attack in stainless steel using ultrasonic energy  

DOEpatents

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

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

1989-08-08

325

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

Microsoft Academic Search

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

H. Fukutomi; S. Lin; A. Nitta

326

Real-time ultrasonic sensing of arc welding processes  

SciTech Connect

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

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

1983-01-01

327

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

328

Compact ultrasonic rotary motors  

Microsoft Academic Search

This paper reviews recent developments of compact ultrasonic rotary motors using piezoelectric resonant vibrations. Following the historical background, three ultrasonic motors recently developed are introduced; windmill, PZT tube and metal tube types. Driving principles and motor characteristics are described in comparison with the conventional ultrasonic motors. Motors with 1.5 mm in diameter and 0.1 mNm in torque have been actually

K. Uchino; B. Koc; S. Dong

2001-01-01

329

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

PubMed

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

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

2012-02-23

330

Dry-contact technique for high-resolution ultrasonic imaging.  

PubMed

To accomplish a high-resolution ultrasonic imaging without wetting a sample, the efficiency of the dry-contact ultrasonic transmission is discussed. In this study, a dry-contact interface is formed on a sample by inserting a thin film between water and a sample, and the pressure is working on the interface by evacuating the air between the film and the sample. A model of dry-contact ultrasonic transmission is presented to assess the signal loss accompanied with the transmission. From the determination of the signal loss caused by the transmission using various films, it was found that the higher frequency ultrasound is transmitted effectively into the sample by selecting an optimum film, which can keep the displacement continuity between the film and the sample during ultrasonic transmission. At last, ultrasonic imaging with the sufficient signal-to-noise ratio (SNR) and high lateral resolution was performed on the delamination in a package and the jointing interface of the ball-grid-array package without wetting the packages. PMID:12839178

Tohmyoh, Hironori; Saka, Masumi

2003-06-01

331

Ultrasonic flowmeters: Half-century progress report, 1955–2005  

Microsoft Academic Search

Ultrasonic flowmeters are one of the fastest-growing technologies within the general field of instruments for process monitoring, measurement and control. Today, acoustic\\/ultrasonic flowmeters utilize clamp-on and wetted transducers, single and multiple paths, paths on and off the diameter, passive and active principles, contrapropagating transmission, reflection (Doppler), tag correlation, vortex shedding, liquid level sensing of open channel flow or flow in

L. C. Lynnworth; Yi Liu

2006-01-01

332

Sonochemical Effect Using Ultrasonic Atomizer at 2.4 MHz  

NASA Astrophysics Data System (ADS)

Sonochemical reactions were demonstrated using a commercial ultrasonic atomizer at 2.4 MHz. The influences of experimental conditions, bottom shape and glass thickness of reactors, irradiation method, and liquid height on the sonochemical yield were discussed. The sonochemical effect was evaluated by potassium iodide dosimetry and degradation of methylene blue. Direct and indirect irradiations were examined. The former had the highest yield. In the latter case, sonochemical yield decreased in the solution because glass prevented the transmission of ultrasonic waves. Poly film, on the other hand, could transmit ultrasonic waves very well without damage.

Shinashi, Kiyoaki; Houkin, Toshinori; Harada, Hisashi

2012-07-01

333

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

334

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

335

High resolution in situ ultrasonic corrosion monitor  

DOEpatents

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

Grossman, Robert J. (Schenectady, NY)

1985-01-01

336

Pulsed radiofrequency effects on the lumbar ganglion of the rat dorsal root: a morphological light and transmission electron microscopy study at acute stage  

PubMed Central

Since the dorsal root ganglia represent the first structure of pain modulation, they are the target of the newest therapies of neuropathic pain. Between these, pulsed radiofrequency (PRF) has been described among the promising non-invasive methods. Although the results encourage the clinical use of this procedure, their mechanism of action is still unclear. Aim of our study was to analyze acute effects of PRF on the rat lumbar ganglion and on nervous fibres running inside it. Clinical works describe PRF treatment as a techinque without any visible neurological deficit. The few disposable histological works are contractictory: some describe no signs of cellular damage and some demonstrate visible intracellular modifications. A total of 20 male Wistar rats were deeply anesthesized. Ten were positioned in a stereotactic system, and exposed to PRF at 2 Hz for 30 s after exposition of paravertebral muscles and positioning of a stimulation needle on left L4 ganglion. The other ten were used as controls. After 1 h, the left dorsal root ganglions L3, L4, L5 of the 20 animals were explanted, fixed in 2.5% Karnowsky solution and prepared for light and transmission electron microscopy. At light microscopy no differences between treated and control animals were observed; at transmission electron microscopy, instead, it was possible to observe that T gangliar cells contained an abnormal abundant smooth reticulum with enlarged cisternae and numerous vacuoles; myelinated axons presented pathological features and their myelin coverage was not adherent. Instead, unmyelinated axons appeared normal in shape and dimension and the Schwann cells surrounding it had intact plasmamembrane. Our results, obtained at acute stage, reveal that the PRF procedure should destroy the myelin envelope of nervous fibres. Further future studies, at chronic stage, should give other information on the prognosis of the myelinic damage.

Reguzzoni, Marcella; Sangiorgi, Simone; Reverberi, Claudio; Borsani, Elisa; Rodella, Luigi F.; Dario, Alessandro; Tomei, Giustino; Dell'Orbo, Carlo

2009-01-01

337

Piezoelectric Ultrasonic Motors  

Microsoft Academic Search

Piezoelectric ultrasonic motors are a new type of actuator. They are characterized by high torque at low rotational speed, simple mechanical design and good controllability. They also provide a high holding torque even if no power is applied. Compared to electromagnetic actuators the torque per volume ratio of piezoelectric ultrasonic motors can be higher by an order of magnitude. Recently

Jorg Wallaschek

1995-01-01

338

Ultrasonic Bone Densitometer.  

National Technical Information Service (NTIS)

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 tra...

J. M. Hoop

1974-01-01

339

Prototype Portable Ultrasonic Spectroscope.  

National Technical Information Service (NTIS)

A portable ultrasonic system designated as the Model 5030 Ultrasonic Spectroscope, has been completed. This system displays both the time-domain rf signal and the spectral content of selected portions of the signal on a single CRT. This advancement signif...

B. J. Spencer G. M. Elfbaum J. L. Hunerwadel K. A. Fowler

1973-01-01

340

Microknife using ultrasonic vibration  

Microsoft Academic Search

The purpose of this research is to develop a minute size knife for cutting of minute objects such as cells. We report on a microknife that cuts the object by using ultrasonic vibration of a sharp needle. We employed a multilayer piezoelectric actuator for generating the ultrasonic vibration for cutting. Also, we made a tactile sensor for the microknife by

Fumihito Arai; Talaharu Amano; T. Fukuda; H. Satoh

2000-01-01

341

Ultrasonic Elliptical Vibration Cutting  

Microsoft Academic Search

A new cutting method named ultrasonic elliptical vibration cutting is proposed and applied to cutting of metals by utilizing a new vibrator to vibrate the cutting tool elliptically at ultrasonic frequency. It is confirmed experimentally that the cutting performance, in terms of the cutting force and the chip thickness, is improved significantly by applying the elliptical vibration to the cutting

Toshimichi Moriwaki; Eiji Shamoto

1995-01-01

342

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

343

Compact piezoelectric ultrasonic motors  

Microsoft Academic Search

This paper reviews recent developments of compact ultrasonic motors using piezoelectric resonant vibrations. Following the historical background, ultrasonic motors using the standing and traveling waves are introduced. Driving principles and motor characteristics are explained in comparison with the conventional electromagnetic motors.

Kenji Uchino; Burhanettin Koc

1999-01-01

344

Ultrasonic in-situ monitoring of setting process of high-performance concrete  

Microsoft Academic Search

The present standard test for the setting times of concrete is the penetration resistance test specified by ASTM C403. This test, while good for standard concrete mixtures, may not be appropriate for high-performance concrete (HPC) because of the high viscosity of the mortar. To address this issue, the ultrasonic pulse velocities (UPV) were measured using an ultrasonic monitoring system during

H. K. Lee; K. M. Lee; Y. H. Kim; H. Yim; D. B. Bae

2004-01-01

345

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

346

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

347

A 3-D PW ultrasonic Doppler flowmeter: theory and experimental characterization  

Microsoft Academic Search

A complete 3-D ultrasonic pulsed Doppler system has been developed to measure quantitatively the velocity vector field of a fluid flow independently of the probe position. The probe consists of four 2.5 MHz piezocomposite ultrasonic transducers (one central transmitter and three receivers separated by 120°) to measure the velocity projections along three different directions. The Doppler shift of the three

Marco Calzolai; Lorenzo Capineri; Ada Fort; Leonardo Masotti; Santina Rocchi; Marco Scabia

1999-01-01

348

Ultrasonic Wave Propagation in Heterogeneous Media  

NASA Astrophysics Data System (ADS)

Piezoelectric ultrasonic transducers typically employ composite structures to improve their transmission and reception sensitivities. The geometry of the composite is regular with one dominant length scale and, since these are resonant devices, this dictates the central operating frequency of the device. In order to construct a wide bandwidth device it would seem natural therefore to utilise resonators that span a range of length scales. In this paper we consider such a device and build a theoretical model to predict its performance. A fractal medium is used as this contains a wide range of length scales and yields to a renormalisation approach. The propagation of an ultrasonic wave in this heterogeneous medium is then analysed and used to construct expressions for the electrical impedance, and the transmission and reception sensitivities of this device as a function of the driving frequency.

Mulholland, Anthony J.

2010-09-01

349

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

350

Ultrasonic Communication Project, Phase 1, FY1999  

SciTech Connect

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

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

2000-06-01

351

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

352

High voltage pulse conditioning  

DOEpatents

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

Stringfield, R.M.; Wheat, R.M. Jr.

1989-02-21

353

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

354

Characterization of oxyfluoride tellurite glasses through thermal, optical and ultrasonic measurements  

NASA Astrophysics Data System (ADS)

A wide range glass system based on the TeO2-WO3-ZnF2 was prepared. A number of physical properties, namely, the glass transition temperature, optical energy gap, Urbach energy, optical basicity, ultrasonic velocity (longitudinal and shear), elastic moduli, Poisson's ratio and Debye temperature were investigated by using several techniques such as: differential thermal analysis, dilatometric, UV-NIR-IR spectra and pulse-echo. These glasses have a high transmission in the visible, the near infrared and infrared regions, very low OH-vibration absorption bands and high thermal stability beyond 169 °C. The results indicated that most properties are observed to be dependent on the ZnF2 content. These physical properties are reported with a view to drawing fluorotellurite optical fibres.

Yousef, El Sayed S.

2005-11-01

355

Ultrasonic evaluation of the physical and mechanical properties of granites.  

PubMed

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

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

2008-03-19

356

EXPERIMENTAL EXAMINATION OF SPEED CONTROL METHODS FOR A TRAVELLING WAVE ULTRASONIC MOTOR  

Microsoft Academic Search

In this study, speed control methods of a travelling wave ultrasonic motor are examined experimentally. A digital controlled drive system is developed to drive ultrasonic motor. The drive system is based on two-phase serial-resonant inverter which includes features of pulse width modulation and pulse frequency modulation techniques. The frequency, amplitude and phase angle of two-phase sinusoidal output of inverter can

Güngör Bal

2003-01-01

357

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.

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

1989-01-01

358

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

359

Ultrasonic testing of reactive powder concrete.  

PubMed

Concrete is a critical material for the construction of infrastructure facilities throughout the world. Traditional concretes consist of cement paste and aggregates ranging in size from 6 to 25 mm that form a heterogeneous material with substantial compressive strength and a very low tensile strength. Steel reinforcement is used to provide tensile strength for reinforced concrete structures and as a composite the material is useful for structural applications. A new material known as reactive powder concrete (RPC) is becoming available. It differs significantly from traditional concrete; RPC has no large aggregates, and contains small steel fibers that provide additional strength and, in some cases, can replace traditional steel reinforcement. Due to its high density and lack of aggregates, ultrasonic inspections at frequencies 10 to 20 times that of traditional concrete inspections are possible. This paper reports on the initial findings of research conducted to determine the applicability of ultrasonic testing techniques for the condition assessment of RPC. Pulse velocities for shear and longitudinal waves and ultrasonic measurement of the modulus of elasticity for RPC are reported. Ultrasonic crack detection for RPC also is investigated. PMID:15055809

Washer, Glenn; Fuchs, Paul; Graybeal, Benjamin A; Hartmann, Joseph Lawrence

2004-02-01

360

Pulsed thermographic inspection and application in commercial aircraft repair  

NASA Astrophysics Data System (ADS)

Pulsed infrared thermographic inspection has proven to be a fast, accurate, reliable and cost effective NDE alternative to traditional ultrasonic NDE of commercial aircraft structures. Accurate damage assessment and verification of proper repair is of utmost importance to the commercial aircraft operator today. Pulsed infrared thermographic inspection can be utilized on a wide variety of aircraft structures with a high degree of accuracy. Acoustical structures that previously could not be scanned with traditional ultrasonic methods can be evaluated using pulsed infrared thermographic inspection.

Ducar, Robert J.

1999-03-01

361

Research on embedding invisible digital watermarking in ultrasonic image  

NASA Astrophysics Data System (ADS)

In this paper, we proposed an adaptive watermarking algorithm to embed invisible digital watermarking in the wavelet domain of ultrasonic image. By analyzing the characteristic of detail sub-band coefficients of the ultrasonic image after discrete wavelet transform (DWT), we use the mean and variance of the detail sub-bands to modify the wavelet coefficients adaptively, and the embedded watermark is invisible to human visual system (HVS) and adapted to the original image. We can derive the just noticeable different (JND), which describes the maximum signal intensity that the various parts of image can tolerate the digital watermarking. By using this digital watermarking technique we can embed a certainty or confidentiality information directly into original ultrasonic images so that the replication and transmission of ultrasonic image can be tracked efficiently. Therefore, the copyright and ownership of ultrasonic images can be protected, which is critical for the authorization usage of the source of ultrasonic images. The experimental results and attack analysis showed that the proposed algorithm is effective and robust to ultrasonic image processing operations and geometric attacks.

Ye, Huashan; Shi, Qing; Ding, Mingyue

2009-10-01

362

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

363

Ultrasonics International - 1973.  

National Technical Information Service (NTIS)

A report is made on the meeting Ultrasonics International - 1973 held in London, England, March 27 - 29, 1973. The meeting covered current information on the latest developments and industrial applications in ultrasound research and technology. This inclu...

A. E. Victor A. H. Waynick

1973-01-01

364

Cepstral Prediction Analysis of the Signal Pathway in AN Ultrasonic A-Scan  

NASA Astrophysics Data System (ADS)

Digital deconvolution of ultrasonic echo signals improves resolution and the quality of ultrasonic images. The Homomorphic deconvolution technique under noisy conditions is applied to simulation results in an ultrasonic pulse-echo amplitude scan line. The simulation includes radiation coupling and transducer response, as well as frequency-dependent absorption in the field medium. An accurate method of estimating the pulse-shaping effects of the transducer and the test medium are developed by using Homomorphic filtering. Experimental results are given which confirm the modelling.

Ali, M. G. S.; Mohamed, A. Raouf

2000-09-01

365

Electrical pulse generator  

DOEpatents

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

Norris, Neil J. (Santa Barbara, CA)

1979-01-01

366

An automated ultrasonic device to measure elastic constants  

Microsoft Academic Search

A not overly expensive and fast to assemble arrangement for measuring ultrasonic velocity changes is discussed. It should be of interest to all who have a Matec (or other) HF pulse generator and receiver at their disposal as well as a digital storage oscilloscope. The measurements shown in this work were made on doped NH4LiSO4.

A. Sarras; H. Kabelka

1994-01-01

367

Testing Results of Magnetostrictive Ultrasonic Sensor Cables for Signal Loss  

SciTech Connect

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

JT Evans

2005-05-01

368

The Performance of the Ultrasonic Flowmeter in Complex Velocity Profiles  

Microsoft Academic Search

The principle of operation of the ultrasonic flowmeter, detecting phase shifts or pulse transit times, is examined. It is shown both theoretically and experimentally that the sensitivity of the flowmeter depends on the fluid velocities averaged along the path of the ultrasound between the transducers. The instrument therefore overestimates the net fluid velocity by 33 percent in case of steady

Urs Gessner

1969-01-01

369

Microcomputer Simulation of a Fourier Approach to Ultrasonic Wave Propagation.  

National Technical Information Service (NTIS)

This thesis uses linear systems approach and the Fourier transform as the basis for a microcomputer program to model pulsed ultrasonic wave propagation. The program computes the acoustic potential in a plane at a given distance from the source. The mathem...

W. H. Reid

1992-01-01

370

A neural network architecture for ultrasonic nondestructive testing  

Microsoft Academic Search

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

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

1991-01-01

371

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

372

Ultrasonic attenuation measurements in Egyptian dry compact rocks  

Microsoft Academic Search

The attenuation of ultrasonic waves in specific dry rocks is measured in laboratory. The pulse echo technique is used to determine attenuation coefficients (?) and quality factor (Q) values of different kinds of rocks in the frequency range of 1-5 MHz. The laboratory measurements showed that, the attenuation coefficients are linearly proportional to frequency (constant Q) in the considered frequency

S. M. El-Sherbiny; A. G. Hassanin; H. A. Nofal; S. M. Abd-Alkader

2003-01-01

373

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

374

Elastic properties of sand-peat moss mixtures from ultrasonic measurements  

SciTech Connect

Effective remediation of an environmental site requires extensive knowledge of the geologic setting, as well as the amount and distribution of contaminants. Seismic investigations provide a means to examine the subsurface with minimum disturbance, Laboratory measurements are needed to interpret field data. In this experiment, laboratory tests were performed to characterize manufactured soil samples in terms of their elastic properties. The soil samples consisted of small (mass) percentages (1 to 20 percent) of peat moss mixed with pure quartz sand. Sand was chosen as the major component because its elastic properties are well known except at the lowest pressures. The ultrasonic pulse transmission technique was used to collect elastic wave velocity data. These data were analyzed and mathematically processed to calculate the other elastic properties such as the modulus of elasticity. This experiment demonstrates that seismic data are affected by the amount~of peat moss added to pure sand samples. Elastic wave velocities, velocity gradients, and elastic moduli vary with pressure and peat moss amounts. In particular, ultrasonic response changes dramatically when pore space fills with peat. With some further investigation, the information gathered in this experiment could be applied to seismic field research.

Trombino, C N

1998-09-02

375

Use of guided ultrasonic waves for characterization of cancellous and cortical bone  

NASA Astrophysics Data System (ADS)

The possibility of accessing mechanical, structural, and geometrical parameters of both the cancellous and cortical bone components by different modes of ultrasonic guided waves has been demonstrated in several laboratories in Europe and the USA. Making measurements of acoustic wave propagation parameters in a wide frequency band, e.g., from 100 kHz to several MHz, enables assessment of bone layers at different depths from the bone surface. At lower frequencies, the acoustic wave velocity is found to be sensitive to changes of the cortical thickness in middleshaft areas. In epiphyseal zones, the measured low-frequency (100-kHz) wave, velocity reflects contributions of both the spongy and compact bone components and can be sensitive to changes of the trabecular structure. At higher frequencies in the MHz range, the main acoustic mode manifested in the received signal is related to the longitudinal wave, which characterizes mainly the elastic properties of the compact bone closer to the periosteum. Measurements of the ultrasonic pulse propagation parameters in a broad frequency band using surface transmission scanning mode enables the possibility to obtain the profile of acoustic properties of long bones. [Work supported by NIH and NASA.

Sarvazyan, Armen; Tatarinov, Alexej

2004-10-01

376

Evaluation of ultrasonic techniques for detection of stress-corrosion cracks in stainless steel piping. [100 and 250 mm  

Microsoft Academic Search

Ultrasonic pulse-echo methods are evaluated for their adequacy in the detection of intergranular stress-corrosion cracking in Type 304 stainless steel nuclear reactor piping. The effectiveness of ultrasonic examinations of 100-mm and 250-mm Schedule 80 Type 304 stainless steel pipes is discussed. Both welded and unwelded pipes were investigated with commercially available ultrasonic systems. Hand-held transducers of various frequencies, sizes, beam

D. S. Kupperman; C. L. Johnson; W. A. Ellingson

1976-01-01

377

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

378

Stretched nanosecond pulses of a Q-switched Nd-YAG laser: Transmission through optical fibres and in vitro effects on human calcified tissues  

Microsoft Academic Search

Using a new Q-switched Nd-YAG laser prototype (1064 nm), every initial pulse (15 ns or 33 ns duration, 10 Hz repetition rate,\\u000a 2×E energy, Pmax power) was transformed into two successive pulses (each one with 15 or 33 ns duration, 1×E energy) delayed\\u000a by 27 ns. With a 15 ns initial pulse, the two 15 ns components (each one with

J. Englender; J. P. Beregi; D. Fayoux; R. Astier; J. Perennec; A. Antonetti; Y. Lecarpentier

1992-01-01

379

Ultrasonic Flowmeters: A Progress Report.  

National Technical Information Service (NTIS)

This progress report describes the components and system configuration of the prototype ultrasonic flowmeter and initial flow testing. It is the second in a series of progress reports on the development and testing of ultrasonic flowmetering concepts. The...

W. D. Wittekind

1980-01-01

380

Ultrasonic-aided fabrication of gold nanofluids  

NASA Astrophysics Data System (ADS)

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).

Chen, Hui-Jiuan; Wen, Dongsheng

2011-12-01

381

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

382

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

PubMed

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

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

2006-06-06

383

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

384

Orthogonal Golay code based ultrasonic imaging without reducing frame rate  

Microsoft Academic Search

Orthogonal Golay codes feature perfect sidelobe cancellation properties, and are simple to implement because they have elements of +1 and -1 only. However, the frame rate is reduced by one half due to the requirement of two consecutive transmissions per scanline. This paper presents an ultrasonic B-mode imaging method using orthogonal complementary Golay codes without reducing the frame rate while

Moo-Ho Bae; Woo-Youl Lee; Mok-Kun Jeong; Sung-Jae Kwon

2002-01-01

385

Structural improvement for solder joint failure in ultrasonic plastic assembly  

Microsoft Academic Search

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

Jie Shen; Xianlong Jin

2008-01-01

386

A Power Line Radio and Ultrasonic Interference Environmental Study  

Microsoft Academic Search

An experimental study has been carried out to find the effects of environmental aging surrounding on the radio and ultrasonic noise characteristics of single strand aluminium conductors used by electric companies for 400 kV transmission lines. The performance of similar conductors been energized at equal time periods under the same voltage stresses in the H.V. laboratory and in an industrial

I. S. HALKIADIS

2005-01-01

387

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

388

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

389

Development of an ultrasonic clutch  

Microsoft Academic Search

In the present paper, a newly developed ultrasonic clutch can solve problems of conventional passive elements, such as time delay, instability, and large size by, by using unique characteristics of ultrasonic motor, as fast response, silent motion, and non-magnetic feature. The clutch locks or releases the rotor by the use of ultrasonic levitation phenomenon. First, we have designed the structure

Tatsuya Koyama; K. Takemura; Takashi Maeno

2003-01-01

390

Development of an ultrasonic clutch  

Microsoft Academic Search

In the present paper, a newly developed ultrasonic clutch is proposed. The ultrasonic clutch can solve problems of conventional passive elements, such as time delay, instability, and large size, by using unique characteristics of ultrasonic motor, as fast response, silent motion, and non-magnetic feature. It can also be designed to be smaller than conventional elements due to its simple structure.

Tatsuya Koyama; K. Takemura; Takashi Maeno

2003-01-01

391

Ultrasonic dip seal maintenance system  

DOEpatents

A system for removing impurities from the surfaces of liquid dip seals and or wetting the metal surfaces of liquid dip seals in nuclear components. The system comprises an ultrasonic transducer that transmits ultrasonic vibrations along an ultrasonic probe to the metal and liquid surfaces of the dip seal thereby loosening and removing those impurities.

Poindexter, Allan M. (Pleasant Hills, PA); Ricks, Herbert E. (Forest Hills, PA)

1978-01-01

392

Investigation of intracranial media ultrasonic monitoring model.  

PubMed

The objectives are to investigate the peculiarities of the ultrasound pulse propagation through human extra/intracranial media by mathematical simulation and to confirm the simulation results experimentally by proving the suitability of the ultrasonic time-of-flight measurement method for human intracranial media (IM) physiological non-invasive monitoring. The mathematical model of ultrasound pulse propagation through the human extra/intracranial media is described. The simulation of various physiological phenomena were performed to determine the relationship between the characteristics of the transmitted ultrasound pulse through the human head and the acoustic properties of the IM. It is shown that non-invasive monitoring of the IM acoustic properties is possible by measuring the changes of the ultrasonic signal time-of-flight and the oscillation period. The influence made by variations in acoustic parameters of the external tissue/skull bones on the non-invasive measurement data is investigated and methods of compensation of that influence are presented. The models were applied for developing of a new non-invasive sonographic intracranial pressure (ICP) monitor (Vittamed). Comparative studies of this monitor with the invasive ICP monitor (Camino) have shown the possibility of achieving clinically acceptable accuracy of the long term non-invasive ICP monitoring of head injured patients in intensive care units. PMID:12160053

Petkus, Vytautas; Ragauskas, Arminas; Jurkonis, Rytis

2002-05-01

393

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

Microsoft Academic Search

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

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

1999-01-01

394

Laser-induced phonon spectroscopy. Optical generation of ultrasonic waves and investigation of electronic excited-state interactions in solids  

Microsoft Academic Search

Crossed laser pulse excitation generates high amplitude, counterpropagating, ultrasonic waves (acoustic phonons of selected wave vector) via direct coupling between the optical electromagnetic field and the material acoustic field. The technique allows optical generation of ultrasonic waves, conveniently tunable to at least 20 GHz. The coupling mechanism, which does not involve optical absorption, is discussed in detail in terms of

Keith A. Nelson; D. R. Lutz; M. D. Fayer; Larry Madison

1981-01-01

395

Streamflow monitoring with ultrasonic recorders  

SciTech Connect

In September 1983, four new streamflow monitoring sites were established in a west Chestnut Ridge catchment at the Oak Ridge National Laboratory. Ultrasonic level/flow recorders were used to monitor the streamflow at these sites. These recorders use an ultrasonic sound pulse and digital circuitry to measure the stage or flow. By use of a FROM (functional read only memory), the recorder can operate in a linear or proportional mode. In the linear mode, the data are recorded as a fraction of a predetermined maximum stage, and in the proportional mode, the data are recorded as a fraction of a predetermined maximum flow. Data are recorded on an EPROM (erasable programmable read only memory) which can later be translated using an Apple IIe microcomputer with an interface card. EPROMs are erased using an ultraviolet lamp but circular charts on the recorders provide a permanent pen and ink stage or flow record. New computer software was developed for the Apple IIe to meet the specific needs of streamflow reporting, because the available software was aimed at the water and wastewater industry and provided overly extensive reports. The new software is designed to read the EPROM and convert the hexadecimal data to decimal data, then store the data on a disk. An editing program allows the user to estimate any lost data or correct any erroneous data. A report generator computes the streamflow based on a stage-flow rating table and generates a daily summary report which provides the total flow volume, the average flow, and the daily maximum and minimum flow.

Melroy, L.A.; Huff, D.D.

1985-01-01

396

Ultrasonic humidification for telecommunications  

SciTech Connect

This article examines two installations which demonstrate that ultrasonic humidification is an excellent option for large-scale commercial installations. Many existing telephone switching centers constructed 20 to 30 years ago were equipped with electro-mechanical switching equipment that was not sensitive to humidity. Today's sophisticated solid-state telecommunications equipment requires specific levels of relative humidity to operate properly. Over the last several years, Einhorn Yaffee Prescott (formerly Rose Beaton + Rose) designed two of the largest ultrasonic humidification systems at telecommunications buildings located in Cheshire, Conn., and White Plains, N.Y. The Cheshire project was a retrofit to the existing system in a 1960s building; the White Plains project involved an upgrade to a totally new air handling system, including an ultrasonic humidification component, in a 1950s building.

Longo, F. (Einhorn Yaffee Prescott, White Plains, NY (United States))

1994-03-01

397

Pulsed phase-locked loop calibration over frequency  

Microsoft Academic Search

This paper presents a method of correcting for unwanted phase shifts introduced by interchanging ultrasonic transducers and other measurement system components when using the pulsed phase-locked loop (PPLL) ultrasonic system. Theory is derived mathematically separating phase errors into their constituents. The relationship to a previously derived method of determining the number of periods into the tone-burst, at which the system

Mark E. Froggatt; Sidney G. Allison; J. P. Moore

1996-01-01

398

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

399

A biologically compatible implantable ultrasonic marker.  

PubMed

An implantable passive ultrasonic marker has been developed which can be detected with a conventional pulse echo imaging system. The marker consists of a planar array of 1/16 in. diameter stainless steel (316L) spheres and produces a distinct and characteristic reflection signature due to reverbation within the spheres. The marker has undergone both in vitro and in vivo tests and is biologically compatible for chronic implantation. It is consistently detectable at depths up to 10 cm from the transducer. An application to the detection of flow conditions in aortocoronary bypass grafts is suggested. PMID:6603700

Stern, R A; Hill, B C; Gaudiani, V A; Green, S E; Ingels, N B

400

Design guidelines for medical ultrasonic arrays  

NASA Astrophysics Data System (ADS)

The basics of ultrasonic transducer array design in the frequency range useful for medical imaging are discussed. Performance parameters of importance in transducer design are considered, including sensitivity, coupling constant, band width, frequency downshift, pulse duration, beam focusing properties, and electrical matching. 2D and 3D effects must also be taken into account. The advantages of computer modeling in 3D with finite element analysis code are highlighted. The principles of multi-element array transducers useful for 2D real-time scanning are reviewed. 2D arrays provide the opportunity of focusing the elevation beam dimension in the short axis, or make possible full 3D scanning volumes.

McKeighen, Ronald E.

1998-05-01

401

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

402

PULSE AMPLITUDE ANALYZER  

DOEpatents

A pulse-height analyzer system of improved design for sorting and counting a series of pulses, such as provided by a scintillation detector in nuclear radiation measurements, is described. The analyzer comprises a main transmission line, a cathode-ray tube for each section of the line with its deflection plates acting as the line capacitance; means to bias the respective cathode ray tubes so that the beam strikes a target only when a prearranged pulse amplitude is applied, with each tube progressively biased to respond to smaller amplitudes; pulse generating and counting means associated with each tube to respond when the beam is deflected; a control transmission line having the same time constant as the first line per section with pulse generating means for each tube for initiating a pulse on the second transmission line when a pulse triggers the tube of corresponding amplitude response, the former pulse acting to prevent successive tubes from responding to the pulse under test. This arrangement permits greater deflection sensitivity in the cathode ray tube and overcomes many of the disadvantages of prior art pulse-height analyzer circuits.

Gray, G.W.; Jensen, A.S.

1957-10-22

403

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

404

Ultrasonic comb transducer for smart materials  

NASA Astrophysics Data System (ADS)

Installation of a small multi-element comb type ultrasonic transducer is proposed as a component of a smart structure. It can be used in either an active or passive mode in carrying out ultrasonic bulk or guided wave nondestructive evaluation. Theoretical methods are developed and experimental results are presented for guided wave generation and mode control with this very efficient and versatile novel comb type ultrasonic transducer. Excitation and probe design is crucial in mode selection. The comb transducer generates waves that are influenced by such parameters as number of elements, spacing between elements, dimension, pulsing sequence, and pressure distribution. The excited elastic field depends on the excitation frequency, plate thickness, and elastic properties. Techniques are studied to optimize the applied loading and the comb transducer design parameters so that only modes that are most sensitive to particular material characteristics can be generated. Complete understanding of the comb transducer parameters and their impact on the elastic field allows us to efficiently generate higher order modes as well as low phase velocity modes which are valuable in composite material characterization. Sample experiments are presented for various plate and tube like structures.

Rose, J. L.

1998-04-01

405

Direct ultrasonic measurement of solid propellant ballistics  

NASA Astrophysics Data System (ADS)

This article illustrates the application of an ultrasonic pulse-echo technique to determine the burning rate of a composite solid propellant as a function of pressure. An evaluation of the measurement uncertainty of the method is also presented. Unlike the more traditional strand burner techniques, where dozens of constant pressure tests are necessary, the ultrasonic technique measures the burn surface position thousands of times per second as the pressure varies. This reduces the number of tests necessary to determine the ballistic characteristics of the propellant by an order of magnitude. This work presents new methods to characterize the changing speed of sound in the propellant and quantitative estimates of the measurement uncertainty in the burning rate measurement. The results of the uncertainty analysis showed that the measurement is accurate to around 4%. The propellant samples were tested in a closed-combustion vessel, under pressurization rates of up to 15.8 MPa/s. The data obtained with the closed-combustion-vessel tests using the ultrasonic method are experimentally congruent with tests conducted in strand burners in steady-state conditions.

di Salvo, Roberto; Dauch, Frédéric; Frederick, Robert A.; Moser, Marlow D.

1999-11-01

406

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

407

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

408

Scanning ultrasonic probe  

DOEpatents

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

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

1982-01-01

409

Scanning ultrasonic probe  

DOEpatents

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

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

1980-12-09

410

Ultrasonic Lamb wave tomography  

Microsoft Academic Search

Nondestructive evaluation (NDE) of aerospace structures using traditional methods is a complex, time-consuming process critical to maintaining mission readiness and flight safety. Limited access to corrosion-prone structure and the restricted applicability of available NDE techniques for the detection of hidden corrosion or other damage often compound the challenge. In this paper we discuss our recent work using ultrasonic Lamb wave

Kevin R. Leonard; Eugene V. Malyarenko; Mark K. Hinders

2002-01-01

411

Ultrasonic soldering irons  

Microsoft Academic Search

Two instruments which have been developed to facilitate the tinning of aluminium and other light metal surfaces are described. Intense ultrasonic vibrations from a magnetostriction transducer are used to produce cavitation in molten solder in contact with the metal surface. The cavitation pressures are sufficient to remove the oxide film from the metal so that alloying can occur. One instrument

B. E. Noltingk; E. A. Neppiras

1951-01-01

412

Ultrasonic Soldering of Aluminium  

Microsoft Academic Search

FOR some years it has been known that it is possible to tin aluminium and its alloys by subjecting their surface to the action of intense ultrasonic vibration at the same time as molten solder is applied1-3 but the mechanism for this effect does not seem to have been studied. We have now established that the process is one of

B. E. Noltingk; E. A. Neppiras

1950-01-01

413

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

414

Widebeam ultrasonic flowmeter  

Microsoft Academic Search

A novel method of a clamp-on ultrasonic flowmeter is proposed. With this method, a widebeam is examined theoretically by the application of spatial frequency analysis. It is demonstrated that plate modes generated in a pipe wall exert bad effects on flowrate measurement. This method can reduce such effects. This method makes it possible to automatically compensate for the deviation of

R. Motegi; S. Takeuchi; T. Sato

1990-01-01

415

Laser ultrasonic microscopy  

Microsoft Academic Search

As the field of laser ultrasonics has matured over the past decade, our main focus has been on developing techniques for characterising materials in ever-finer detail, in terms of both spatial resolution and information content. We have worked to improve both the instrumentation and our understanding of the interactions between light, sound and material properties. This effort results in a

S. D. Sharples; M. Clark; R. J. Smith; R. J. Ellwood; W. Li; M. G. Somekh

2011-01-01

416

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

417

Ultrasonic force microscopy on strained antimony nanoparticles.  

PubMed

Ultrasonic force microscopy (UFM) is used to resolve the elastic nanostructure of strained antimony (Sb) particles. These nanoparticles were formed by aggregation and spontaneous rapid crystallization of thermally deposited Sb onto the (0001) basal planes of highly oriented pyrolytic graphite (HOPG) and molybdenum disulfide (MoS(2)). UFM reveals clear contrast within individual nanoparticles, which can be attributed to differences in the local stiffness. This interpretation is confirmed by transmission electron microscopy (TEM) images, in which bending contours prove the existence of strained regions within the nanocrystals. PMID:17570590

Cuberes, M T; Stegemann, B; Kaiser, B; Rademann, K

2007-05-05

418

PULSED INDICATOR CIRCUIT  

DOEpatents

A system is given for detecting incremental changes in a transducer impedance terminating a transmission line. Principal novelty resides in the transducer impedance terminating the line in a mismatch and a pulse generator being provided to apply discrete pulses to the input end of the line. The amplitudes of the pulses reflected to the input end of the line from the mismatched transducer impedance are then observed as a very accurate measure of the instantaneous value of the latter.

Linlor, W.I.; Kerns, Q.A.

1960-11-15

419

Plate Wave Resonance with Air-Coupled Ultrasonics  

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

420

Simulation of transducer-couplant effects on broadband ultrasonic signals  

NASA Astrophysics Data System (ADS)

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

Vary, A.

1980-03-01

421

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

422

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

SciTech Connect

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

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

2007-01-31

423

Simulation of ultrasonic phased array technique for imaging and sizing of defects using longitudinal waves  

Microsoft Academic Search

Phased array ultrasonics can be used as a rapid tool for imaging and sizing crack-like defects. This paper reports the simulation of phased array ultrasonic wave interaction with the defects using the finite-difference time domain (FDTD) method. Experiments were conducted to validate modeling results for pulse–echo simulations of the phased array transducer on a mild-steel (MS) pipe sample with circumferential

L. Satyanarayan; C. Sridhar; C. V. Krishnamurthy; Krishnan Balasubramaniam

2007-01-01

424

Ultrasonic characteristics of solid and liquid materials.  

National Technical Information Service (NTIS)

Non-destructive ultrasonic measurement technique is widely used nowadays in studying the physical properties of materials through the process of measuring ultrasonic wave velocities and attenuation. This paper discusses the measurements of ultrasonic char...

S. P. Chow Sidek Hj Abd Aziz

1990-01-01

425

Non-contact feature detection using ultrasonic Lamb waves  

DOEpatents

Apparatus and method for non-contact ultrasonic detection of features on or within the walls of hollow pipes are described. An air-coupled, high-power ultrasonic transducer for generating guided waves in the pipe wall, and a high-sensitivity, air-coupled transducer for detecting these waves, are disposed at a distance apart and at chosen angle with respect to the surface of the pipe, either inside of or outside of the pipe. Measurements may be made in reflection or transmission modes depending on the relative position of the transducers and the pipe. Data are taken by sweeping the frequency of the incident ultrasonic waves, using a tracking narrow-band filter to reduce detected noise, and transforming the frequency domain data into the time domain using fast Fourier transformation, if required.

Sinha, Dipen N. (Los Alamos, NM)

2011-06-28

426

Ultrasonic texture characterization of aluminum, zirconium and titanium alloys  

SciTech Connect

This work attempts to show the feasibility of nondestructive characterization of non-ferrous alloys. Aluminum alloys have a small single crystal anisotropy which requires very precise ultrasonic velocity measurements for derivation of orientation distribution coefficients (ODCs); the precision in the ultrasonic velocity measurement required for aluminum alloys is much greater than is necessary for iron alloys or other alloys with a large single crystal anisotropy. To provide greater precision, some signal processing corrections need to be applied to account for the inherent, half-bandwidth offset in triggered pulses when using a zero-crossing technique for determining ultrasonic velocity. In addition, alloys with small single crystal anisotropy show a larger dependence on the single crystal elastic constants (SCECs) when predicting ODCs which require absolute velocity measurements. Attempts were made to independently determine these elastics constants in an effort to improve correlation between ultrasonically derived ODCs and diffraction derived ODCs. The greater precision required to accurately derive ODCs in aluminum alloys using ultrasonic nondestructive techniques is easily attainable. Ultrasonically derived ODCs show good correlation with derivations made by Bragg diffraction techniques, both neutron and X-ray. The best correlation was shown when relative velocity measurements could be used in the derivations of the ODCs. Calculation of ODCs in materials with hexagonal crystallites can also be done. Because of the crystallite symmetries, more information can be extracted using ultrasonic techniques, but at a cost of requiring more physical measurements. Some industries which use materials with hexagonal crystallites, e.g. zirconium alloys and titanium, have traditionally used texture parameters which provide some specialized measure of the texture. These texture parameters, called Kearns factors, can be directly related to ODCs.

Anderson, A.J.

1997-10-08

427

A study of an opto-ultrasonic technique for cure monitoring  

NASA Astrophysics Data System (ADS)

This paper will report on efforts directed toward the generation and detection of ultrasonic waves using optical fibers for the purpose of ultrasonic velocity determination. Interferometric optical fiber sensors are embedded within or bonded to the samples. Two different techniques, laser generated ultrasound and piezoelectric ultrasonics, were used in the study of pulse delay measurements in aluminum and in a room temperature cured epoxy. Group velocity in an aluminum sample and in a cured epoxy sample was determined with both techniques. The application of these two methods to epoxy cure monitoring is discussed.

Davis, Andrew; Ohn, Myo M.; Liu, Kexing; Measures, Raymond M.

1991-12-01

428

Ultrasonic Characteristics of Used Corn Oil for Monitoring Quality  

NASA Astrophysics Data System (ADS)

Ultrasonic characteristics of corn oil, heat treated under simulated frying conditions, were evaluated as a possible means of determining changes in frying oil quality with use. Three lots of oil were aged at 170^ circC and tested for changes in kinematic shear viscosity and density at 30^circ C and ultrasonic velocity and attenuation at 2.25, 5, 10, and 50 MHz and 30^circC. A modified pulse echo overlap method was developed for use with digital signals with precision comparable to published techniques. Interpolation of the digital signals improved the precision by one order of magnitude. Significant correlations were measured for kinematic viscosity, ultrasonic velocity, and attenuation between the samples as the amount of heat treatment increased. Significant differences were also noted for all three variables between lots of corn oil and for ultrasonic velocities and attenuation between frequencies. Measurement of attenuation required careful apparatus design and experimental technique to determine differences in used oil samples. The coefficients of the longitudinal bulk modulus were calculated from the data and the elasticity of the oil was shown to increase with use. The viscous term was not shown to change significantly. Ultrasonic measurements of velocity and attenuation were determined to be applicable to in-process determination of frying oil quality.

Lacey, Ronald Earl

429

Ultrasonic techniques for process monitoring and control.  

SciTech Connect

Ultrasonic techniques have been applied successfully to process monitoring and control for many industries, such as energy, medical, textile, oil, and material. It helps those industries in quality control, energy efficiency improving, waste reducing, and cost saving. This paper presents four ultrasonic systems, ultrasonic viscometer, on-loom, real-time ultrasonic imaging system, ultrasonic leak detection system, and ultrasonic solid concentration monitoring system, developed at Argonne National Laboratory in the past five years for various applications.

Chien, H.-T.

1999-03-24

430

Ultrasonic leak detector  

SciTech Connect

This patent describes an ultrasonic leak test apparatus comprising means for sequentially feeding a plurality of workpieces to a test station, means for alternately lifting workpieces in sequence from the transfer means to an elevated position and lowering workpieces onto the transfer means in a lowered position, means for forming a sound chamber enclosing a workpiece on the elevator means, and means for selectively feeding air under pressure into a workpiece enclosed in the chamber, and means for ultrasonically detecting air leakage from within the workpiece. The sequentially-feeding means comprises a transfer line including support means defining a transfer plane, transfer means positioned on opposed sides of the support means for selectively engaging and disengaging workpieces on the support means, and indexing means coupled to the transfer means for selectively indexing the transfer means for moving workpieces sequentially along the support means onto the elevator means.

Fisch, A.C.

1989-03-07

431

Intravascular Ultrasonic Imaging  

PubMed Central

Because conventional imaging methods are inadequate for evaluating human coronary arteries in vivo, an intravascular ultrasonic imaging catheter was developed that allows the arterial wall to be studied in cross-section from within the artery. The catheter incorporates a mechanically rotating 20-MHz transducer, which is designed so that the ringdown occurs within the catheter and imaging is permitted up to the catheter's surface. The device rotates at 1800-rpm within a plastic sleeve and provides real-time cross-sectional images at 30 frames/sec. Preliminary experimental and clinical studies indicate that the intravascular ultrasonic imaging catheter could play a valuable role in providing preoperative information concerning arterial wall thickness and tissue characteristics, in distinguishing normal from diseased arterial wall structures during therapeutic intervention, and in assessing the results of intervention. (Texas Heart Institute Journal 1990; 17:181-9) Images

Tobis, Jonathan M.; Mahon, Donald; Moriuchi, Masahito; Mallery, John A.; Lehmann, Kenneth; Griffith, James; Gessert, James; Zalesky, Paul; McRae, Michael; Dwyer, Mary-Lynn; Henry, Walter L.

1990-01-01

432

Monitoring early age cementitious materials using ultrasonic guided waves  

NASA Astrophysics Data System (ADS)

The evaluation of early age concrete is critical for reducing construction times and ensuring quality. In this study, the use of ultrasonic guided waves for monitoring the development of early age cementitious materials is investigated. A torsional wave is transmitted and received through a waveguide that is embedded in early age mortar or concrete. As the cementitious material sets and hardens, the received wave(s) change, indicating the transition from a semifluid to a solid state. This thesis proposes two systems. The first system is a through-transmission system; a wave is transmitted on one end of an embedded waveguide using a sensor arrangement and then it is received on the opposite end of the rod with another sensor. This approach monitors the attenuation of the fundamental torsional wave mode, resulting from the leakage of energy from the cylindrical steel rod to the surrounding cementitious material. The evolution of the material's properties is related to the energy leakage or attenuation of the guided wave. The second system is a pulse-echo system; a wave is transmitted on one end of a partially embedded waveguide via a sensor arrangement that also receives the reflected signals. This approach monitors both the reflection from the end of the rod and the reflection from the point where the waveguide enters the material. The development of the cementitious material's mechanical properties is related to both the energy leaked into the surrounding material and the energy reflected at the point of entry. The ability of this method to only require access to one side of the specimen makes it attractive for monitoring early age cementitious materials in the field. Experiments were performed on mixtures with varying water-cement ratios (w/c = 0.40, 0.50, and 0.60), chemical admixtures (accelerant and retardant), mineral admixtures (silica fume and fly ash), and coarse aggregate (pea gravel). The time of setting and compressive strength of the various mixtures was determined in accordance with ASTM standards. Experimental results provide evidence that the setting times and compressive strength of early age cementitious materials can be monitored using ultrasonic guided waves.

Borgerson, Jacob L.

433

Flame position ultrasonic interferometer  

NASA Astrophysics Data System (ADS)

A sensitive instrument system for determining the position of the burn front in a rocket motor is disclosed. Separate adjacent transmitter and receiver elements are attached to the rocket motor casing to form an ultrasonic interference system. An ultrasound beam is transmitted to the motor's interior and the reflected beam from the propellant gas burn front is captured by the receiver. The received signal is processed to determine the distance to the propellant-gas interface.

Soss, David A.

1993-12-01

434

Hybrid ultrasonic micromachined motors  

Microsoft Academic Search

A hybrid ultrasonic motor has been fabricated using silicon micromachining and metallic micromechanical components. The concept of elastic force motors (EFMs) is applied for the conversion of standing waves to mechanical energy. Millimeter-size prototypes (6×6×2 mm) show interesting characteristics. Free rotation speed up to 600 rpm and net torque of 50 nNm are observed. Typical applications are the motorization of

G.-A. Racine; R. Luthier; N. F. de Rooij

1993-01-01

435

Magnetic sensing via ultrasonic excitation  

NASA Astrophysics Data System (ADS)

We present ultrasonic techniques for magnetic measurements. Acoustically modulated magnetization is investigated with sensitive rf detection by narrowband loop antennas. Magnetization on the surface of ferromagnetic metals is temporally modulated with the rf frequency of the irradiated ultrasonic waves, and the near-field components emitted from the focal point of the ultrasonic beam are detected. Based on the principle of the acoustically stimulated electromagnetic (ASEM) response, magnetic sensing and tomography are demonstrated by ultrasonic scanning. We show that ASEM imaging combines good acoustic resolution with magnetic contrast. The sensitivity of this method is estimated to be about 6 G/Hz1/2 in our current setup.

Yamada, Hisato; Takashima, Kazuya; Ikushima, Kenji; Toida, Hiraku; Sato, Michitaka; Ishizawa, Yoshiichi

2013-04-01

436

Ultrasonic Transducers for Fourier Analysis.  

ERIC Educational Resources Information Center

Describes an experiment that uses the ultrasonic transducer for demonstrating the Fourier components of waveshapes such as the square and triangular waves produced by laboratory function generators. (JRH)

Greenslade, Thomas B., Jr.

1995-01-01

437

Ultrasonic Transducers for Fourier Analysis.  

ERIC Educational Resources Information Center

|Describes an experiment that uses the ultrasonic transducer for demonstrating the Fourier components of waveshapes such as the square and triangular waves produced by laboratory function generators. (JRH)|

Greenslade, Thomas B., Jr.

1995-01-01

438

Ultrasonic Cutting of Foods  

NASA Astrophysics Data System (ADS)

In the field of food engineering, cutting is usually classified as a mechanical unit operation dealing with size reduction by applying external forces on a bulk product. Ultrasonic cutting is realized by superpositioning the macroscopic feed motion of the cutting device or of the product with a microscopic vibration of the cutting tool. The excited tool interacts with the product and generates a number of effects. Primary energy concentration in the separation zone and the modification of contact friction along the tool flanks arise from the cyclic loading and are responsible for benefits such as reduced cutting force, smooth cut surface, and reduced product deformation. Secondary effects such as absorption and cavitation originate from the propagation of the sound field in the product and are closely related to chemical and physical properties of the material to be cut. This chapter analyzes interactions between food products and ultrasonic cutting tools and relates these interactions with physical and chemical product properties as well as with processing parameters like cutting velocity, ultrasonic amplitude and frequency, and tool design.

Schneider, Yvonne; Zahn, Susann; Rohm, Harald

439

An ultrasonic attenuation parameter for investigating the holding power of non-threaded fixation pins in canine femur (in vitro).  

PubMed

External skeletal fixation (ESF) is a widely used method of fracture treatment but often produces medical complications in the patient. The most serious complication, pin loosening, may lead to pain, poor limb usage, pin tract infection, fracture instability and non-union. Studies of pin loosening are based primarily on pin extraction force measurements, which are destructive in nature. This paper will introduce a method for estimating the extraction force of non-threaded fixation pins based on three related parameters obtained from an ultrasonic pulse introduced into the pin. The ultrasonic test takes advantage of the inherent acoustic absorption across the bone-pin interface. A strong interlock between bone and pin results in increased transmission of ultrasound across the bone-pin interface. This is manifested as heavy signal attenuation, whereas a poor interlock results in considerably less attenuation. The parameters proposed in this paper are intended to quantify attenuation resulting from bone-pin interface interactions. One probe-parameter combination in particular showed considerable sensitivity to the conditions of the bone-pin interface (R2 = 0.79). Further research is suggested and may lead to an operational process for non-invasively evaluating pin security. PMID:8122335

Dickens, J R; Bray, D E; Palmer, R H

1994-01-01

440

Surface nanocrystallization of 316L stainless steel induced by ultrasonic shot peening  

Microsoft Academic Search

A new technique was introduced to realize surface nanocrystallization (i.e. generation of a surface layer of nanostructures) on a 316L stainless steel by means of ultrasonic shot peening treatment. The microstructural evolution of the 316L stainless steel was characterized by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. After the ultrasonic shot peening treatment, obvious grain refinement was

G. Liu; J. Lu; K. Lu

2000-01-01

441

Application of ultrasonic irradiation to the sol–gel synthesis of silver vanadium oxides  

Microsoft Academic Search

An ultrasonic irradiation method was applied to the sol–gel synthesis of silver vanadium oxides (SVO). Transmission electron microscope (TEM), X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA) were conducted to research the ultrasonically accelerated reaction between V2O5 gel and Ag2O powder. Galvanostatic discharge experiments showed that the as prepared cathode active material of Ag2V4O11 and Ag1.2V3O8 have better

Jinggang Xie; Xiaoyu Cao; Jinxia Li; Hui Zhan; Yongyao Xia; Yunhong Zhou

2005-01-01

442

A correlation of air-coupled ultrasonic and thermal diffusivity data for CFCC materials  

SciTech Connect

An air-coupled (non contact) through-transmission ultrasonic investigation has been conducted on 2D multiple ply Nicalon{trademark} SiC fiber/SiNC CFCC panels as a function of number of processing cycles. Corresponding thermal diffusivity imaging was also conducted. The results of the air-coupled ultrasonic investigation correlated with thermal property variations determined via infrared methods. Areas of delaminations were detected and effects of processing cycles were also detected.

Pillai, T.A.K. [Univ. of Wisconsin, LaCrosse, WI (United States). Dept. of Physics; Easler, T.E.; Szweda, A. [Dow Corning Corp., Midland, MI (United States). Advanced Ceramics Program] [and others

1997-01-01

443

Study of microstructure of surface layers of low-carbon steel after turning and ultrasonic finishing  

NASA Astrophysics Data System (ADS)

Profilometry and optical and transmission electron microscopy are used to examine the microstructure of surface layers of a low-carbon ferrite-pearlite steel subjected to turning and ultrasonic finishing. It is shown that turning peaks and valleys have different microstructures, which stipulates manifestation of technological hereditary when processing surfaces of machined parts. Ultrasonic finishing causes the severe plastic deformation of the surface layer, which favors the elimination of a technological heredity that is acquired during turning.

Kovalevskaya, Zh. G.; Ivanov, Yu. F.; Perevalova, O. B.; Klimenov, V. A.; Uvarkin, P. V.

2013-01-01

444

Ultrasonic monitoring and control in plastic manufacturing  

NASA Astrophysics Data System (ADS)

In the search for a simple, robust and noninvasive measurement, the use of sound is explored to monitor polymer processing. A new pulsed ultrasonic measurement is developed based on the absorption of ultrasonic energy (AUE) from the plastic. The signal proves to be computationally efficient, robust and simple to use. The sensitivity of the signal is demonstrated in an injection molding process. The AUE signal led to the investigation of continuous sound waves. Different configurations are surveyed. One such configuration is formed by placing a piezoelectric element normal to the cavity face. In this arrangement, standing waves within the mold develop. When tuned to the appropriate frequency; the waves constructively interfere, producing a mechanical resonance within the mold. This configuration is termed Ultrasonic Resonance Monitoring (URM). Plastic presence at the mold face is shown to change the URM signal. Definitions and terms are proposed to explain the concepts and components necessary to realize a URM system. The design of a URM transducer used to monitor the plastic state within the cavity of an injection molding process is presented. An experiment is conducted to study the effects of the plastic on the transducer. Changes in the injection molding parameters are shown to modify the URM profile. In an effort to explain and understand the URM signal, a continuous wave acoustic model is used to identify influential physical parameters. An experiment is conducted to measure the acoustic properties of the plastic during molding. Throughout the molding process, pulsed ultrasonic waveforms are collected while simultaneously measuring the impedance of the URM transducer. The acoustic 3 properties are extracted from the waveforms and used in the model to simulate the response of the URM transducer. Two examples are presented to show how the signal may be used to monitor and control the injection molding process. The first example predicts part weight using features found in the URM profile. The second example uses the URM signal as the transfer indicator in one-step transfer control. The URM based transfer is compared against ram position and cavity pressure transfer and is shown to mold parts with the smallest deviation of part weight.

Edwards, Russell K.

445

Ultrasonic properties of fluorosilicate glass-ceramics at cryogenic temperatures  

Microsoft Academic Search

The longitudinal ultrasonic wave velocity and attenuation, and shear wave velocity for machinable fluorosilicate glass-ceramic (MACOR) samples (regular shelf stock, annealed to 900°C, and 1000°C for 10 hrs) were measured as the functions of frequency and temperature with the pulse-echo method. The frequency and temperature range used were 5 MHz to 50 MHz, and 100 K to 300 K respectively.

Jin H. So; D. H. Green; S. S. Yun

2003-01-01

446

Underwater acoustic imaging using capacitive micromachined ultrasonic transducer arrays  

Microsoft Academic Search

Capacitive micromachined ultrasonic transducers (CMUTs) have recently emerged as an alternative technology to piezoelectric transducers, offering advantages such as wide bandwidth, ease of fabricating large arrays and potential for integration with electronic circuits. In this paper, we present 2D and 3D pulse-echo imaging results using ID linear and 2D rectangular CMUT arrays, respectively. The aim of this paper is to

O. Oralkan; A. S. Ergun; C.-H. Cheng; J. A. Johnson; M. Karaman; B. T. Khuri-Yakub

2002-01-01

447

Ultrasonic testing of adhesive bonds of thin metal sheets  

Microsoft Academic Search

This article discusses the use of pulse-echo ultrasonic testing for the inspection of adhesive bonds between thin metal sheets (0.8mm). The method is based on the measurement of the reflection coefficient at the metal\\/adhesive interface. After describing briefly the physical aspects of the phenomenon, an index is defined to detect defective zones of the joint (both for the lack of

Luca Goglio; Massimo Rossetto

1999-01-01

448

Comparison of pulsed field gel electrophoresis and repetitive sequence polymerase chain reaction as genotyping methods for detection of genetic diversity and inferring transmission of Salmonella  

Microsoft Academic Search

Pulsed field gel electrophoresis (PFGE) using restriction enzymes AvrII, SpeI, and XbaI, and repetitive sequence polymerase chain reaction (Rep-PCR) using BOX, ERIC, and REP primers, were compared with respect to their ability to detect genetic differences among 68 Salmonella isolates from nine Illinois swine farms. Both genotyping methods had high reproducibility of fragment numbers (reliability>0.9) and sizes (reliability>0.85), and produced

Ronald M. Weigel; Baozhen Qiao; Belete Teferedegne; Dong Kyun Suh; David A. Barber; Richard E. Isaacson; Bryan A. White

2004-01-01

449

Pulsed radiofrequency effects on the lumbar ganglion of the rat dorsal root: a morphological light and transmission electron microscopy study at acute stage  

Microsoft Academic Search

Since the dorsal root ganglia represent the first structure of pain modulation, they are the target of the newest therapies\\u000a of neuropathic pain. Between these, pulsed radiofrequency (PRF) has been described among the promising non-invasive methods.\\u000a Although the results encourage the clinical use of this procedure, their mechanism of action is still unclear. Aim of our\\u000a study was to analyze

Marina Protasoni; Marcella Reguzzoni; Simone Sangiorgi; Claudio Reverberi; Elisa Borsani; Luigi F. Rodella; Alessandro Dario; Giustino Tomei; Carlo Dell’Orbo

2009-01-01

450

Blind echolocation using ultrasonic sensors  

Microsoft Academic Search

This paper proposes a navigation aid for the blind using echolocation principle and ultrasonic sensors. The device is for obstacles avoidance by detecting near objects in front of the user and shall trigger an audible alarm. Based on the echolocation principle, the ultrasonic beam is emitted in a certain direction in space through a transmitter. The beam is reflected from

Izzatdin Abdul Aziz; Sajee Mahamad; Mazlina Mehat; Nazleeni Samiha

2008-01-01

451

Ultrasonic abrasion of quartz crystals  

Microsoft Academic Search

In the present work, we investigate the wear mechanisms associated with the ultrasonic abrasion of quartz. Ultrasonic abrasion was carried out in X-, Y-, Z- and AT-cut plates of natural quartz and Z-cut plates of synthetic quartz. The counter bodies, square and cylindrical, were fabricated from stainless steel. The abrasive slurry was made from boron carbide with mean grain size

P. L Guzzo; A. A Raslan; J. D. B De Mello

2003-01-01

452

Eggshell Cutter Using Ultrasonic Vibration  

Microsoft Academic Search

An eggshell cutting apparatus which utilizes ultrasonic vibration was developed, replacing the conventional apparatus which uses an air cutter, to cut eggshells at the blunt end of eggs. Two ultrasonic vibration sources were used: one with longitudinal vibration only and the other with torsional vibration plus longitudinal vibration. Eggshell cutting experiments using these vibration sources were conducted. The eggshell cutting

Hikaru Miura

2003-01-01

453

Ultrasonic Determination of Body Composition.  

National Technical Information Service (NTIS)

The object of the study was to determine the feasibility of using ultrasonic techniques to determine the volume of fat, muscle, and bone tissue of the living body. Ultrasonic equipment, including a mechanical scanning and recording device was used to prod...

J. R. Stouffer

1968-01-01

454

Obstacle avoidance with ultrasonic sensors  

Microsoft Academic Search

A mobile robot system, capable of performing various tasks for the physically disabled, has been developed. To avoid collision with unexpected obstacles, the mobile robot uses ultrasonic range finders for detection and mapping. The obstacle avoidance strategy used for this robot is described. Since this strategy depends heavily on the performance of the ultrasonic range finders, these sensors and the

JOHANN BORENSTEIN; YORAM KOREN

1988-01-01

455

Ultrasonic method for cleaning teeth  

US Patent & Trademark Office Database

An improved method for cleaning teeth is disclosed. The method for cleaning teeth includes: applying ultrasonic waves of a first frequency through a liquid media to the teeth for a first period of time; and applying ultrasonic waves of a second frequency through a liquid media to the teeth for a second period of time.

2005-04-19

456

Powder compaction with ultrasonic assistance  

Microsoft Academic Search

The compaction behaviour of a ceramic powder can be improved by ultrasonic assistance, only when ultrasounds are used at pressures lower than a critical value,PC. This critical pressure is connected with the limit of mobility of the powder grains under ultrasonic vibrations. Its value depends on the characteristics of the powder, as well as those of the ultrasounds: frequency, amplitude,

E. Emeruwa; J. Jarrige; J. Mexmain; M. Billy; K. Bouzouita

1990-01-01

457

Ultrasonic actuators for nanometre positioning  

PubMed

This paper deals with ultrasonic motors based on bimodal plate vibrations and their application to nanometre resolution stepper positioning systems. The concept of a linear ultrasonic motor drive capable of nanometric steps, long-range travel and reversible controlled motion is presented. The motor concept developed is based on the superposition of a longitudinal and bending vibrations of a rectangular resonator. The ultrasonic motor model based on system identification via discrete observations and prediction has been developed for control applications. The control algorithm for ultrasonic motors has been developed and theoretical investigations have been made. The open loop positioning system with designed stepper ultrasonic drive produced 10 nm resolution and 5% displacement repeatability. The system with computer controlled position feedback has shown 0.3 micron positioning accuracy over the 100 mm positioning range. PMID:10829621

Snitka

2000-03-01

458

Improvement of ultrasonic transducers by optimizing constructional parameters  

NASA Astrophysics Data System (ADS)

This article shows a simple 5-step procedure for improving the performance of ultrasonic transducers. It focuses on the effect of matching layers, backing, and series inductance on the frequency spectrum and pulse shape of transducers, paying particular attention to the insertion loss, which determines the transducer sensitivity. The procedure is accomplished using results obtained from a computer program designed at Southwest Research Institute. This computer program, based on the KLM model, provides graphic representations of the frequency spectrum and pulse shape for certain transducer designs. Final optimization results given by the computer program for one particular transducer are compared to the actually fabricated transducer.

Alcazar, D. G.

459

Hydrodynamic ultrasonic probe  

DOEpatents

An improved probe for in-service ultrasonic inspection of long lengths of a workpiece, such as small diameter tubing from the interior. The improved probe utilizes a conventional transducer or transducers configured to inspect the tubing for flaws and/or wall thickness variations. The probe utilizes a hydraulic technique, in place of the conventional mechanical guides or bushings, which allows the probe to move rectilinearly or rotationally while preventing cocking thereof in the tube and provides damping vibration of the probe. The probe thus has lower friction and higher inspection speed than presently known probes.

Day, Robert A. (Livermore, CA); Conti, Armond E. (San Jose, CA)

1980-01-01

460

Characterization of reinforced syntactic foams using ultrasonic imaging technique  

Microsoft Academic Search

Non-destructive evaluation of defects like voids in syntactic foam reinforced with epoxy compatible chopped strand glass fibres,\\u000a employing ultrasonic C-scan immersion through transmission method, was under-taken. The results showed that in four of the\\u000a five similarly processed foam samples, the voids were uniformly spread while in the fifth, which was processed by a different\\u000a route, a large spread of low

C S Karthikeyan; C R L Murthy; S Sankaran; Kishore

1999-01-01

461

Design of embedded endoscopic ultrasonic imaging system  

Microsoft Academic Search

Endoscopic ultrasonic imaging system is an important component in the endoscopic ultrasonography system (EUS). Through the ultrasonic probe, the characteristics of the fault histology features of digestive organs is detected by EUS, and then received by the reception circuit which making up of amplifying, gain compensation, filtering and A\\/D converter circuit, in the form of ultrasonic echo. Endoscopic ultrasonic imaging

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

2008-01-01

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

Wave-based defect detection and interwire friction modeling for overhead transmission lines  

Microsoft Academic Search

In this study, the feasibility of continuous, online monitoring of power lines using ultrasonic waves is considered. Local\\u000a and global wave-based approaches for wire break detection in overhead transmission lines are presented. Both methods use a\\u000a sending\\/receiving transducer to generate an ultrasonic, longitudinal, elastic wave in the cable. Defects in the cable cause\\u000a a portion of the incident ultrasonic wave

Thomas Haag; Brad M. Beadle; Helge Sprenger; Lothar Gaul

2009-01-01

464

Pulse shaping system  

DOEpatents

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

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

1999-03-23

465

Pulse shaping system  

DOEpatents

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

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

1999-03-23

466

Analysis of laser ultrasonic measurements of surface waves on elastic spheres  

NASA Astrophysics Data System (ADS)

In conventional ultrasonic nondestructive evaluation studies, piezoelectric transducers are used to generate sound waves in solids via a couplant that transmits the mechanical motions. In recent years, a different method of generating sound in solids, pulsed laser heating, was introduced by White. This method is noncontacting, requires no coupling medium, and operates directly on the surface of the specimen. Noncontacting ultrasonic detection using laser interferometers of several types has also been developed. Laser techniques can achieve essentially point source and point detection of ultrasonic motion through focusing. Laser ultrasonics can, therefore, be used on objects with complex shapes, e.g., curved surfaces, and are applicable to material shapes more commonly found in industry. Often the goal of ultrasonic measurements is to determine material properties such as Lame's elastic constants. The conventional approach measures longitudinal and shear wave speeds between two parallel flat surfaces. The work reported here demonstrates the versatility of laser ultrasonics by directly measuring the surface motion of a solid sphere generated by ablation from a pulsed laser beam in the ablation regime. The results compare well with elastodynamic theoretical calculations, where the ablation source is approximated well with elastodynamic theoretical calculations, where the ablation source is approximated as a normal impulse on the surface. This work suggests that an algorithm could be formulated to measure elastic properties of targets with curved surfaces.

Koo, L. S.; Telschow, K. L.

467

Ultrasonic characterization of delamination in aeronautical composites using noncontact laser generation and detection.  

PubMed

The characterization of delamination in composite plates with ultrasonic waves generated and detected by lasers is presented. Composite materials have become one of the most important structural materials in the aviation industry because of their excellent mechanical properties, such as high specific stiffness and antifatigue. This paper reports a new application of the laser ultrasonic technique to perform nondestructive detection of carbon-fiber-reinforced plastic (CFRP) and continuous-fiber-reinforced ceramic matrix composites (CFCCs) containing artificial internal defects, based on propagation characteristic of ultrasonic waves generated by pulse laser with a wavelength of 1064 nm and pulse duration of 10 ns. A laser interferometer based on two-wave mixing is used to measure ultrasonic wave signals. The main advantage of this technique over conventional ultrasonic testing techniques is the ability to carry out detection without using coupling agents. The research results prove that the laser ultrasonic technique is effective for the detection of internal defects in both CFRP and CFCC composite components, which should promote and expand the application of the technique in the aviation industry. PMID:24085123

Sun, Guangkai; Zhou, Zhenggan; Chen, Xiucheng; Wang, Jie

2013-09-10

468

Ultrasonic Lamb wave tomography  

NASA Astrophysics Data System (ADS)

Nondestructive evaluation (NDE) of aerospace structures using traditional methods is a complex, time-consuming process critical to maintaining mission readiness and flight safety. Limited access to corrosion-prone structure and the restricted applicability of available NDE techniques for the detection of hidden corrosion or other damage often compound the challenge. In this paper we discuss our recent work using ultrasonic Lamb wave tomography to address this pressing NDE technology need. Lamb waves are ultrasonic guided waves, which allow large sections of aircraft structures to be rapidly inspected for structural flaws such as disbonds, corrosion and delaminations. Because the velocity of Lamb waves depends on thickness, for example, the travel times of the fundamental Lamb modes can be converted into a thickness map of the inspection region. However, extracting quantitative information from Lamb wave data has always involved highly trained personnel with a detailed knowledge of mechanical waveguide physics. Our work focuses on tomographic reconstruction to produce quantitative maps that can be easily interpreted by technicians or fed directly into structural integrity and lifetime prediction codes. Laboratory measurements discussed here demonstrate that Lamb wave tomography using a square perimeter array of transducers with algebraic reconstruction tomography is appropriate for detecting flaws in aircraft materials. The speed and fidelity of the reconstruction algorithms as well as practical considerations for person-portable array-based systems are discussed in this paper.

Leonard, Kevin R.; Malyarenko, Eugene V.; Hinders, Mark K.

2002-12-01

469

Laser-ultrasonic technologies for medicine  

NASA Astrophysics Data System (ADS)

This review tackles the problem of further developing laser- ultrasonic medical technologies and gives the comparison of different laser and ultrasound combinations. The features of combined influence on biotissue are explicated with due regard for mechanic, ultrasonic (US), and thermal effects. The review present the effect of self-cleaning an optical fiber tip from the laser destruction products of biotissue, the result of research on the possibility of laser-US technology applications in endoscopy, and the ways of suppressing unwanted bending oscillations. Various spheres and peculiarities of applying laser-US technologies are discussed, including microsurgery, cosmetology, transcutaneous drug delivery, and the treatment of chronic prostatitis and infected wounds. Furthermore, the analysis of transcutaneous drug delivery methods employing a portable pulsed Er:YAG laser is presented. Drug diffusion has been shown to be enhanced under acoustic and US effects. The photo-vacuum drug injection mechanism recently suggested is discussed. It turned out that laser-US technology can be suitable for both impregnating the photosensitizer in local photodynamic therapy procedures and conducting microsurgery operations involving drug injection. Treatment of infectious processes based on the bactericidal action of photosensitizers and ultrasound due to the cavitation effect in solutions is described. An additional therapeutic effect can be achieved via the US intermingling of solutions with their simulations illumination by a matrix of red lasers or light diodes. An outlook on further developing laser-US technology and the ways of its apparatus realization are considered.

Zharov, Vladimir P.; Latyshev, Alexei S.

1999-06-01

470

Time-domain model of the ultrasonic wave propagation in an inhomogeneous anisotropic viscoelastic fluid\\/solid multilayer medium: application to cortical bone  

Microsoft Academic Search

Cortical bone quality is assessed in clinical practice using axial transmission (AT) devices, which allow the measurement of quantitative ultrasonic parameters such as the first arriving signal (FAS) velocity. However, the physical interaction between an ultrasonic wave and cortical bone remains poorly understood due to the complex nature of the bone structure. Cortical bone and the surrounding soft tissues are

G. Haiat; S. Naili; M.-B. Vu; Q. Grimal; M. Talmant; C. Desceliers; C. Soize

2009-01-01

471

Pulsed thermographic inspection and application in commercial aircraft repair  

Microsoft Academic Search

Pulsed infrared thermographic inspection has proven to be a fast, accurate, reliable and cost effective NDE alternative to traditional ultrasonic NDE of commercial aircraft structures. Accurate damage assessment and verification of proper repair is of utmost importance to the commercial aircraft operator today. Pulsed infrared thermographic inspection can be utilized on a wide variety of aircraft structures with a high

Robert J. Ducar

1999-01-01

472

Determination of inlet transmission and conversion efficiencies for in situ measurements of the nocturnal nitrogen oxides, NO3, N2O5 and NO2, via pulsed cavity ring-down spectroscopy.  

PubMed

Pulsed cavity ring-down spectroscopy is a highly sensitive method for direct absorption spectroscopy that has been applied to in situ detection of NO3, N2O5 and NO2 in the atmosphere from a variety of platforms, including ships, aircraft, and towers. In this paper, we report the development of schemes to significantly improve the accuracy of these measurements. This includes the following: (1) an overall improvement in the inlet transmission efficiencies (92 +/- 2% for NO3 and 97 +/- 1% for N2O5) achieved primarily through a reduction in the inlet residence time; and (2) the development of a calibration procedure that allows regular determination of these efficiencies in the field by addition of NO3 or N2O5 to the inlet from a portable source followed by conversion of NO3 to NO2. In addition, the dependence of the instrument's sensitivity and accuracy to a variety of conditions encountered in the field, including variations in relative humidity, aerosol loading, and VOC levels, was systematically investigated. The rate of degradation of N2O5 transmission efficiency on the inlet and filter system due to the accumulation of inorganic aerosol was determined, such that the frequency of filter changes required for accurate measurements could be defined. In the absence of aerosol, the presence of varying levels of relative humidity and reactive VOC were found to be unimportant factors in the instrument's performance. The 1 sigma accuracy of the NO3, N2O5, and NO2 measured with this instrument are -9/+12, -8/+11, +/- 6%, respectively, where the -/+ signs indicate that the actual value is low/high relative to the measurement. The largest contribution to the overall uncertainty is now due to the NO3 absorption cross section rather than the inlet transmission efficiency. PMID:18588318

Fuchs, Hendrik; Dubé, William P; Ciciora, Steven J; Brown, Steven S

2008-06-28

473

Polyurea thin film ultrasonic transducers for nondestructive testing and medical imaging.  

PubMed

Ultrasonic transducers using polyurea piezoelectric thin film are studied in this paper. Aromatic polyurea thin films, prepared by vapor deposition polymerization, have useful characteristics for use as an ultrasonic transducer. This paper presents the fabrication and experimental evaluation of ultrasonic transducers formed using polyurea films. First, the vapor deposition polymerization process using two monomers is briefly reviewed, and the temperature conditions for higher piezoelectric constants are explored. Second, in order to test the fundamental characteristics of this material as a high-frequency, ultrasonic transducer, a polyurea film of 2.5 microm thickness was deposited on a silicon substrate. In the pulse/echo experiment results, a resonant frequency of about 100 MHz was observed. Third, we fabricated a concave point focus transducer and a cylindrical line focus transducer. To examine the performances of the focus transducers, two-dimensional images of a coin and V(z) curve measurements for an aluminum surface were demonstrated. PMID:18019256

Nakazawa, Marie; Kosugi, Tsutomu; Nagatsuka, Hiromi; Maezawa, Akihiro; Nakamura, Kentaro; Ueha, Sadayuki

2007-10-01

474

Ultrasonic-aided fabrication of gold nanofluids.  

PubMed

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). PMID:21711710

Chen, Hui-Jiuan; Wen, Dongsheng

2011-03-07

475

Ultrasonic studies on polystyrene/styrene butadiene rubber polymer blends filled with glass fiber and talc.  

PubMed

The compatibility of solid blends: PS/SBR, PS/SBR filled with glass fiber and PS/SBR filled with talc were studied using ultrasonic pulse echo technique. Measurements were carried out at room temperature (298 K) and a frequency of 3 MHz. The ultrasonic velocity for the compressional wave and that for shear wave have been measured to obtain the elastic moduli data by knowing of density. The variation of ultrasonic wave velocities and elastic moduli with weight percent of the blend was found to be linear in PS/SBR blend, indicating some degree of compatibility but the drawback of elastic moduli indicate incompatibility of the system blend, while it deviates from linearity in blends of PS/SBR filled with glass fiber and talc but the increase in elastic moduli indicates that there is an increase in degree of compatibility between PS and SBR due to adding of glass fiber or talc. The ultrasonic absorptions for longitudinal wave in the temperature range from 298 to 423 K in the studied system were measured using ultrasonic pulse echo technique. T