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1

Through-transmission\\/pulse-echo ultrasonic equipment evaluation  

Microsoft Academic Search

A literature search was conducted to identify commercially available ultrasonic equipment for nondestructive inspection of bonded structures used in advanced high performance aircraft for flaws such as delaminations, debonds, and impact damage. More than fifty instruments were identified from the search. The majority (approximately 20 percent) of the instruments are based on other techniques such as resonance, acousto-ultrasonic, and so-called

Hegeon Kwun

1987-01-01

2

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

3

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

4

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

5

Pulse shaping with transmission lines  

DOEpatents

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

Wilcox, Russell B. (Oakland, CA)

1987-01-01

6

Wireless power transmission using ultrasonic guided waves  

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

7

Medical tomograph system using ultrasonic transmission  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

8

Pulsed lasers for quantitative ultrasonic NDE  

NASA Astrophysics Data System (ADS)

The use of pulsed lasers for ultrasound generation in various media recommends itself for NDE in virtue of the noncontact character of the method and the generation of a wide bandwidth over a small source area; the size and shape of the source may also be varied by means of optical techniques. Attention is presently given to the use of an electromagnetic acoustic transducer as a detector, the possibility of ultrasonic imaging by means of the synthetic aperture technique and the testing of adhesive bonds through Lamb wave generation.

Hutchins, David A.

9

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

10

Optimising ultrasonic wideband Rayleigh wave generation by pulsed electromagnetic coils  

Microsoft Academic Search

Transient ultrasonic Rayleigh wave generation by pulsed electromagnetic coils operating via the Lorentz force mechanism is investigated. Optimal coil design is calculated by considering the entire ultrasonic generation system including the pulse generator, coil shape and size, and the electromagnetic coupling between coil and metal sample. The study is carried out through theoretical modelling and comparison with experimental measurements taken

X. Jian; S. Dixon; R. S. Edwards

2005-01-01

11

Ultrasonic spectrum analysis using frequency-tracked gated RF pulses  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

12

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

13

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

14

Breast imaging in coronal planes with simultaneous pulse echo and transmission ultrasound.  

PubMed

Clear delineation of breast architecture was achieved with compound pulse echo ultrasound imaging in which the images were acquired in the coronal planes used for quantitative transmission ultrasonic computed tomography. Since most connective tissue planes in the breast radiate toward the nipple, compound scans from the sides of the breast record normal interfaces more consistently and reveal greater symmetries in normal portions of relatively full breasts than do conventional scans in sagittal or transverse planes. Simultaneous acquisition of the pulse echo images and images representing the local ultrasound attenuation coefficient and speed of ultrasound suggested complementary role for reflection and through-transmission images in breast cancer detection. The high quality of pulse echo images in coronal planes provides the potential for more complete pulse echo diagnosis and the basis for spatial correlation of lesions viewed in pulse echo and ultrasonic computed tomograms. These observations may permit routine ultrasonic computed tomography of the breast in the clinical setting. PMID:7302585

Carson, P L; Meyer, C R; Scherzinger, A L; Oughton, T V

1981-12-01

15

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

16

Resonant ultrasonic wireless power transmission for bio-implants  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

17

Computer controlled ultrasonic inspection of pulsed magnetic welded fuel pins  

Microsoft Academic Search

Pulsed magnetic welding is being evaluated as a process for welding fuel cladding to the end plug for nuclear fuel pins. A continuous metallurgical bond is required between the plug and clad because this joint must function as a gas and coolant seal for the fuel pin. An ultrasonic technique utilizing a computer controlled scanner was developed to inspect these

J. E. Horn; D. O. Hunter; T. E. Michaels

1979-01-01

18

Measurements of ultrasonic pulse distortion produced by human chest wall.  

PubMed

Ultrasonic wavefront distortion produced by transmission through human chest wall specimens was measured over a two-dimensional aperture. Measured pulse wavefronts were sometimes disrupted by secondary wavefronts produced by interaction between the transmitted pulses and the bone and cartilage structures of the rib cage. The secondary wavefronts produced large distortions in the received waveforms and interfered with the determination of the wavefront distortion caused by soft-tissue inhomogeneities. The effects of secondary wavefronts were minimized by reducing the region of analysis. Differences in arrival time and energy level between these restricted regions and references that account for geometric delay and spreading were computed. Spectral changes were assessed by calculating a waveform similarity factor that is decreased from 1.0 by changes in waveform shape. For 16 different intercostal spaces, the arrival time fluctuations of the measured waveforms had an average (+/-s.d.) rms value of 21.3 (+/-8.4) ns and an average correlation length of 2.50 (+/-0.62) mm. The energy level fluctuations had an average rms value of 1.57 (+/-0.45) dB and an average correlation length of 1.98 (+/-0.33) mm, and the average waveform similarity factor was 0.964 (+/-0.012). For soft-tissue inhomogeneities in chest wall specimens, the average rms arrival time and energy level fluctuations were less than half those measured for the abdominal wall. However, although the average correlation length of the arrival time fluctuations was less than half that found for the abdominal wall, the average correlation length of the energy level fluctuations was similar to that of the abdominal wall. PMID:9104034

Hinkelman, L M; Szabo, T L; Waag, R C

1997-04-01

19

Wideband optical measurements of ultrasonic pulses  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

20

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

21

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

22

Coded Pulse Excitation for Ultrasonic Strain Imaging  

PubMed Central

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

Liu, Jie; Insana, Michael F.

2009-01-01

23

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

Microsoft Academic Search

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

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

1999-01-01

24

Ultrasonic pulsed phase locked loop interferometer for bolt load measurements  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

25

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

E-print Network

The maturity characterization of orange fruit by using high frequency ultrasonic echo pulse method of the maturity of orange fruit by the ultrasonic echo pulse method with immersion in water. This study relates the strong attenuation of the ultrasounds in the texture of fruits and vegetables, we limited our study only

Boyer, Edmond

26

Noninvasive and localized neuronal delivery using short ultrasonic pulses and microbubbles  

E-print Network

Noninvasive and localized neuronal delivery using short ultrasonic pulses and microbubbles James J to large molecular agents. Yet the range of acoustic parameters responsible for drug delivery remains to be difficult. We pro- pose a new basis for ultrasonic pulse design in drug delivery through the blood

Konofagou, Elisa E.

27

Simulation of ultrasonic pulse propagation through the abdominal wall.  

PubMed

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

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

1997-08-01

28

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

29

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

PubMed

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

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

2014-02-01

30

Local SAR in Parallel Transmission Pulse Design  

PubMed Central

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 RF 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 MRI scan. Additionally, the algorithm yields a Protocol-specific Ultimate Peak in Local SAR (PUPiL 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 7T eight-channel transmit array. The method reduced peak local 10g 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

2011-01-01

31

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

32

Disbond monitoring at wing stringer tip based on built-in ultrasonic transducers and a pulsed laser  

NASA Astrophysics Data System (ADS)

An active ultrasonic diagnostic method for monitoring the occurrence and growth of a disbond at a wing stringer tip was developed and verified using built-in piezoelectric lead-zirconate-titanate transducers. The diagnosis was based on the ultrasonic arrival time delay caused by an increase in the disbond-induced wave path and can provide quantitative information on the disbond length. The change in the ultrasonic amplitude, which is a conventional measure for disbond detection, was also included in the diagnostics. Finally a single transmission and multiple reception method was used to obtain the arrival time and amplitude distributions. Another active ultrasonic diagnostic tool based on a pulsed laser ultrasonic generation was proposed for a nondestructive evaluation to obtain more reliable results on the damage detected using the built-in transducers. The diagnostics were verified using a metal skin-stringer structure as an experimental model, and then applied to monitoring the disbond at a stringer tip in a composite wingbox.

Lee, Jung-Ryul; Takatsubo, Junji; Toyama, Nobuyuki

2007-08-01

33

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

NASA Technical Reports Server (NTRS)

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

Kishoni, D.

1985-01-01

34

Ultrasonic ranging and data telemetry system  

Microsoft Academic Search

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

Hugh R. Brashear; Michael S. Blair; James E. Phelps; Martin L. Bauer; Charles H. Nowlin

1990-01-01

35

An Evaluation of the Effect of Pulsed Ultrasound on the Cleaning Efficacy of Passive Ultrasonic Irrigation  

Microsoft Academic Search

IntroductionMultiple activations of the irrigant by using pulsed ultrasound may enhance the removal of dentin debris because of repeated acceleration of the irrigant. The aim of this study was to evaluate the effect of pulsed ultrasound on passive ultrasonic irrigation (PUI) in its ability to remove artificially placed dentin debris from a simulated apical oval extension within standardized root canals.

Lei-Meng Jiang; Bram Verhaagen; Michel Versluis; Chiara Zangrillo; Doris Cuckovic; Lucas W. M. van der Sluis

2010-01-01

36

Optical generation and detection of acoustic pulse profiles in gases for novel ultrasonic absorption spectroscopy  

NASA Astrophysics Data System (ADS)

We demonstrate a new all-optical, frequency-multiplexed and fast technique for gas-phase ultrasonic absorption spectroscopy. A pulsed laser produces a short-duration acoustic pulse in the gas sample, and the acoustic pulse profiles at two distances are monitored by focused continuous probe beams. Fourier decompositions of these probe deflection signals provide the absorption spectrum, and examples for CO2 + H2O mixture are given. Ultrasonic propagation speeds in the MHz regime are also obtained for several gases.

Tam, A. C.; Leung, W. P.

1984-05-01

37

Far infrared spectroscopy with subpicosecond electrical pulses on transmission lines  

Microsoft Academic Search

Optically generated and detected electrical pulses on transmission lines in the subpicosecond range have frequencies extending up to 1 THz, thereby covering the far-infrared region of the spectrum from 0 to 30\\/cm. The propagation of these short pulses through a section of the transmission line covered with erbium iron garnet was studied, which shows distinct absorption lines in the far-infrared

R. Sprik; I. N. Duling III; C.-C. Chi; D. Grischkowsky

1987-01-01

38

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

39

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

40

Prediction of concrete strength using ultrasonic pulse velocity and artificial neural networks.  

PubMed

Ultrasonic pulse velocity technique is one of the most popular non-destructive techniques used in the assessment of concrete properties. However, it is very difficult to accurately evaluate the concrete compressive strength with this method since the ultrasonic pulse velocity values are affected by a number of factors, which do not necessarily influence the concrete compressive strength in the same way or to the same extent. This paper deals with the analysis of such factors on the velocity-strength relationship. The relationship between ultrasonic pulse velocity, static and dynamic Young's modulus and shear modulus was also analyzed. The influence of aggregate, initial concrete temperature, type of cement, environmental temperature, and w/c ratio was determined by our own experiments. Based on the experimental results, a numerical model was established within the Matlab programming environment. The multi-layer feed-forward neural network was used for this purpose. The paper demonstrates that artificial neural networks can be successfully used in modelling the velocity-strength relationship. This model enables us to easily and reliably estimate the compressive strength of concrete by using only the ultrasonic pulse velocity value and some mix parameters of concrete. PMID:18589471

Trtnik, Gregor; Kavcic, Franci; Turk, Goran

2009-01-01

41

Concrete compressive strength prediction using ultrasonic pulse velocity through artificial neural networks  

Microsoft Academic Search

Numerous attempts to use ultrasonic pulse velocity (UPV) as a measure of compressive strength of concrete has been made due to obvious advantages of non-destructive testing methods. The present study is conducted for prediction of compressive strength of concrete based on weight and UPV for two different concrete mixtures (namely M20 and M30) involving specimens of two different sizes and

Manish A. Kewalramani; Rajiv Gupta

2006-01-01

42

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

PubMed

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

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

2013-07-01

43

Viscoelastic measurement of tissue-like phantom using a pulsed wave Doppler ultrasonic system  

Microsoft Academic Search

The purpose of this research was to develop a pulsed wave Doppler ultrasonic measuring system for the quantitative investigation and determination of the elasticity and viscosity of living soft tissue. A pilot study of the tissue-like gel phantom was applied for investigating the feasibility of the system. Theories in continuum mechanics, viscoelastic biosolids, wave propagation, Doppler ultrasound, communication and digital

Chun-Ju Hou; Kao-Chi Chung

2003-01-01

44

EFFECT OF DIFFERENT CURING CONDITIONS ON ULTRASONIC PULSE VELOCITY AND COMPRESSIVE STRENGTH OF LIGHTWEIGHT CONCRETE  

Microsoft Academic Search

The paper reports the results of an experimental study on investigation of the effect of curing conditions on the relationship between the ultrasonic pulse velocity and compressive strength of lightweight concrete with silica fume. In addition to concrete mixture with only Portland cement, concrete mixture with 0%, 10% of silica fume replaced with cement by weight was prepared. Maximum grain

Ahmet CO?KUN; Harun TANYILDIZI

45

Artificial Neural Network Approach to Predict Compressive Strength of Concrete through Ultrasonic Pulse Velocity  

Microsoft Academic Search

Plenty of efforts to use ultrasonic pulse velocity (UPV) as a measure of concrete compressive strength have been implemented in the recent years due to obvious advantages of nondestructive testing methods. In this article, an artificial neural network (ANN) approach has been proposed for the evaluation of relationship between concrete compressive strength and UPV values by using the data obtained

M. Bilgehan; P. Turgut

2010-01-01

46

Local SAR in parallel transmission pulse design  

E-print Network

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 ...

Lee, Joonsung

47

Influence of a gradient of material properties on ultrasonic wave propagation in cortical bone: application to axial transmission.  

PubMed

The aim of this work is to evaluate the effect of a spatial gradient of material properties (mass density and stiffness coefficients) of cortical bone on its ultrasonic response obtained with an axial transmission device. Therefore, a two-dimensional finite element time-domain method is derived to model transient wave propagation in a three-layer medium composed of an inhomogeneous transverse isotropic solid layer sandwiched between two acoustic fluid layers and excited by an acoustic linear source located in one fluid layer, delivering broadband ultrasonic pulses. The model couples the acoustic propagation in both fluid media with the elastodynamic response of the solid layer. A constant spatial gradient of material properties is considered for two values of bone thicknesses corresponding to relatively thick and thin bone widths. For a thin bone (0.6 mm) compared to wavelength (around 4 mm at 1 MHz), the results are in good agreement with a S(0) Lamb wave assuming a homogeneous material with spatially averaged material properties. For a thick bone (4 mm), the results are in agreement with the propagation of a lateral wave and allow the derivation of an equivalent contributing depth in the case of a transverse isotropic inhomogeneous solid layer. PMID:19507985

Haïat, Guillaume; Naili, Salah; Grimal, Quentin; Talmant, Maryline; Desceliers, Christophe; Soize, Christian

2009-06-01

48

Development of Polygonal Buffer Rods for Ultrasonic Pulse-Echo Measurements  

NASA Astrophysics Data System (ADS)

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

Foudzi, F. M.; Ihara, I.

2014-06-01

49

Determination of the principal parameter of ultrasonic pulse velocity and compressive strength of lightweight concrete by using variance method  

Microsoft Academic Search

Experiments are usually made to finding maximum ultrasonic pulse velocity and compressive strength of lightweight concrete.\\u000a In this study, ultrasonic pulse velocity and compressive strength of lightweight concrete made with scoria aggregate, silica\\u000a fume and fly ash was investigated experimentally and statistically. This article adopts Taguchi approach. The Taguchi method\\u000a has been used to determine the optimum conditions and to

Harun Tanyidizi; Ahmet Coskun

2008-01-01

50

Single-frequency pulsed laser oscillator and system for laser-ultrasonics  

NASA Astrophysics Data System (ADS)

We present a new pulsed laser oscillator and system for the optical detection of ultrasound in materials. A single-frequency laser oscillator based on a pulse pumped Nd:YAG rod inside a ring cavity is proposed. The laser delivers single-frequency pulses of 35 W power. Pulse to pulse stability of the laser is obtained with a classical Pound-Drever-Hall method. Power of about 1 kW can be obtained when the second rod of a dual-rod pumping chamber is used as an amplifier. The performance of the system is then investigated with a GaAs photorefractive crystal-based two-wave mixing phase demodulator. In particular, the intensity noise of the laser can be made small enough to allow the detection limit to be set by the shot-noise of the laser. The coherence length of the laser is about 20 m, which makes it a versatile laser-ultrasonic inspection system operated with a two-wave mixing-based phase demodulator. A complete compact and affordable system is obtained when the second rod of the pumping chamber is used to operate a short pulse laser for the generation of ultrasound. Tests of this laser-ultrasonic system on metallic samples are presented.

Carrion, Lionel; Blouin, Alain; Padioleau, Christian; Bouchard, Paul; Monchalin, Jean-Pierre

2004-09-01

51

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

NASA Technical Reports Server (NTRS)

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

Sachse, W.; Ruoff, A. L.

1974-01-01

52

Inverse filter technique for high-precision ultrasonic pulsed wave range Doppler sensors  

Microsoft Academic Search

Ultrasonic pulsed wave range Doppler sensors provide application in various fields, e.g, intruder alarm systems or autonomous vehicle steering. The time-frequency methods commonly used in these sensors, however, inhere the problem that, due to the transducer's non-constant and direction-dependent transfer functions, the Doppler frequency cannot be determined with the high accuracy needed for such applications. The easiest way to improve

H. Ruser; M. Vossiek; A. von Jena; V. Magori

1997-01-01

53

Method and apparatus for characterizing reflected ultrasonic pulses  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

54

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

SciTech Connect

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

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

2008-10-15

55

Pulse propagation in composite tubes for ultrasonic evaluation  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

56

Generation and detection of ultrasonic waves in micrometric and sub-micrometric films using picosecond laser pulses  

Microsoft Academic Search

In this paper, the effects of the laser pulse duration (100 fs - 12 ps) are investigated on the generation and the detection of photo-acoustic signals. A model of generation and detection of ultrasonic waves with ultra-shorts laser pulses is presented. An interferometric detection technique is used to probe the amplitude and the phase changes of the perturbed optical reflectivity.

C. Rossignol; R. Libgot; B. Audoin; J. M. Rampnoux; S. Dilhaire

2003-01-01

57

Correlation of Human Metal Model and Transmission Line Pulsing Testing  

Microsoft Academic Search

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

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

2011-01-01

58

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

59

Effect of the pulse trajectory on ultrasonic fluid velocity measurement  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

60

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

PubMed

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

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

2008-07-01

61

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

62

Target Ranging Using Ultrasonic Sensitivity-Compensated Signal and Pulse Compression  

NASA Astrophysics Data System (ADS)

A new approach of frequency-modulated pulse compression for target ranging using ultrasonic pulse-echo is discussed. To acquire a receiving signal with a broader bandwidth, a flatter spectrum, and a higher signal-to-noise ratio, the use of a sensitivity-compensated transmitting signal is proposed. To compensate for the uneven and narrow bandwidth of the receiving signal brought forth by the sensitivities of ultrasonic transducers, the sensitivity-compensated signal is calculated by inversing the spectrum of the response function majorly composed of the sensitivities of transmitters and receivers. Moreover, instead of the transmitting signal, a reference receiving signal with an expanded flat spectrum measured priorly is employed for cross-correlation calculation with the receiving signal. The efficiency of the proposed method, compared with both the inverse and matched filtering methods using a chirp wave as the transmitting signal, is studied by a target ranging experiment in air. The results show that the spectrum of the receiving signal is compensated for and expanded using the sensitivity-compensated signal, and that unevenness of less than -20 dB in the spectrum of the receiving signal of the chirp wave is compensated for efficiently. Furthermore, the results of pulse compression show that, using the proposed method, the signal-to-noise ratio of the compressed pulse can be expected to be improved by more than that derived by the inverse filtering method, while the pulse width is shortened and the resolution is improved up to about 1/3 of that acquired by the matched filtering method with a chirp wave.

Toh, Ryo; Motooka, Seiichi

2009-07-01

63

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

NASA Astrophysics Data System (ADS)

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

Sietins, Jennifer Mueller

64

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

65

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

66

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

PubMed

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

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

2014-07-01

67

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

68

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

69

Detection of Arterial Wall Boundaries Using an Echo Model Composed of Multiple Ultrasonic Pulses  

NASA Astrophysics Data System (ADS)

The assessment of the intima-media thickness (IMT) of the carotid arterial wall, which is the most frequently used indicator to diagnose atherosclerosis by ultrasound, involves the measurement of the lumen-intima boundary (LIB) and media-adventitia boundary (MAB). In this study, using the mean squared error (MSE) method and by applying the template matching technique, an adaptive model of an ultrasonic echo, which is obtained from an ultrasonic pulse measured with a hydrophone, was fitted with the measured in vivo RF echo to estimate the boundaries of the carotid arterial wall. In the present study, the frequency and phase of the adaptive model were considered to improve the accuracy in the determination of the LIB and MAB. For a 7.5-mm-long short segment of the carotid artery in the longitudinal direction, the average IMTs estimated by the improved technique and the previous method were 502+/-61 and 558+/-120 µm, respectively, showing a decrease in the standard deviation by the proposed method. Moreover, the result obtained by the improved technique presented only 0.4% difference between the automatically detected boundary and the manually detected boundary, which is smaller than that obtained by the previous method (10.7% difference). These results verified that the boundary detected by the improved technique was more accurate than that detected by the previous method.

Ibrahim, Nabilah; Hasegawa, Hideyuki; Kanai, Hiroshi

2013-07-01

70

An ultrasonic system for diameter pulse tracking in arteries: problems and pitfalls.  

PubMed

Non-invasive ultrasonic techniques for measuring the mechanical behaviour of large arteries have a potential clinical application for physiological studies of the circulation and early detection of degenerative arterial disorders. A newly developed system for such purposes, comprising two double-echo trackers with zero-crossing phase-locked circuits and interfacing a B-mode real-time scanner, has been introduced for on-line recording of the diameter in a selected aortic segment. The aim of this report is to draw attention to the limitations of the technique in order to avoid misinterpretation of results. The various problems associated with the use of phase-locked echo followers for tracking sonic echoes of vessel pulse waves are summarized. The high spatial resolution of the measuring system is essential for estimating the elastic properties of the vessel, because the fractional changes of the diameter waveform during a heart cycle are small compared with the swings of intravascular pressure. Measuring errors may originate from either human or technical sources. From several viewpoints correct alignment of the ultrasonic beam vis-à-vis the vessel segment under consideration is crucial for obtaining valid measures. A thorough knowledge of the physics involved is essential for an adequate use of the instrument. With correct use, easily reproducible and reliable estimations are obtained of the mechanical properties of large vessel walls. PMID:8326507

Manor, D; Dahl, P; Benthin, M; Ruzicka, R; Lindström, K; Gennser, G

1993-01-01

71

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

SciTech Connect

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

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

2014-02-18

72

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

NASA Astrophysics Data System (ADS)

Strongly nonlinear vibration phenomena in metal plates excited by high-power ultrasonic pulses in different conditions are studied experimentally and theoretically. The experimental conditions for generating quasisubharmonics and subharmonics are found and discussed. The plate vibrations are characterized by waveforms, frequency spectra, pseudostate portraits, and Poincaré maps. Then, a three-degree-of-freedom vibroimpact-dynamic model is presented to explore the generation mechanisms of the quasisubharmonic and subharmonic vibrations in the plates. According to the model, the intermittent contact-impact forces caused by the interactions between the transducer horn tip and the plate are considered as the main source for generating the complex nonlinear vibration in the plate. The numerical calculation results can explain reasonably the observed experimental phenomena.

Chen, Zhao-jiang; Zhang, Shu-yi; Zheng, Kai; Kuo, Pao-kuang

2009-07-01

73

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

NASA Technical Reports Server (NTRS)

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

Roth, Don J. (Inventor)

1997-01-01

74

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

NASA Technical Reports Server (NTRS)

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

Roth, Don J. (Inventor)

1995-01-01

75

Pulsed eddy current and ultrasonic data fusion applied to stress measurement  

NASA Astrophysics Data System (ADS)

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

Habibalahi, A.; Safizadeh, M. S.

2014-05-01

76

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

77

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

78

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

PubMed

We demonstrate essentially distortionless 50 km fiber transmission for approximately 500 fs pulses, using dispersion-compensating fiber and a programmable pulse shaper as a spectral phase equalizer. This distance is approximately five times longer than previously achieved at similar pulse widths. PMID:16007770

Jiang, Z; Yang, S D; Leaird, D E; Weiner, A M

2005-06-15

79

Multiband tissue classification for ultrasonic transmission tomography using spectral profile detection  

NASA Astrophysics Data System (ADS)

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

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

2004-04-01

80

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

PubMed

The relative importance of the fat and muscle layers of the human abdominal wall in producing ultrasonic wavefront distortion was assessed by means of direct measurements. Specimens employed included six whole abdominal wall specimens and twelve partial specimens obtained by dividing each whole specimen into a fat and a muscle layer. In the measurement technique employed, a hemispheric transducer transmitted a 3.75-MHz ultrasonic pulse through a tissue section. The received wavefront was measured by a linear array translated in the elevation direction to synthesize a two-dimensional aperture. Insertion loss was also measured at various locations on each specimen. Differences in arrival time and energy level between the measured waveforms and computed references that account for geometric delay and spreading were calculated. After correction for the effects of geometry, the received waveforms were synthetically focused. The characteristics of the distortion produced by each specimen and the quality of the resulting focus were analyzed and compared. The measurements show that muscle produces greater arrival time distortion than fat while fat produces greater energy level distortion than muscle, but that the distortion produced by the entire abdominal wall is not equivalent to a simple combination of distortion effects produced by the layers. The results also indicate that both fat and muscle layers contribute significantly to the distortion of ultrasonic beams by the abdominal wall. However, the spatial characteristics of the distortion produced by fat and muscle layers differ substantially. Distortion produced by muscle layers, as well as focal images aberrated by muscle layers, show considerable anisotropy associated with muscle fiber orientation. Distortion produced by fat layers shows smaller-scale, granular structure associated with scattering from the septa surrounding individual fat lobules. Thick layers of fat may be expected to cause poor image quality due to both scattering and bulk absorption effects, while thick muscle layers may be expected to cause focus aberration due to large arrival time fluctuations. Correction of aberrated focuses using time-shift compensation shows more complete correction for muscle sections than for fat sections, so that correction methods based on phase screen models may be more appropriate for muscle layers than for fat layers. PMID:9857521

Hinkelman, L M; Mast, T D; Metlay, L A; Waag, R C

1998-12-01

81

Nonlinear Transmission Performance of Very High Spectral Efficiency WDM Comparing Nyquist Pulse Shaping and OFDM  

E-print Network

spectrally efficient optical transmission. It is well known that electrically generated OFDM (which from hereNonlinear Transmission Performance of Very High Spectral Efficiency WDM Comparing Nyquist Pulse on the performance of optical transmission systems [1]. To meet an expected tenfold increase in global IP traffic

Haddadi, Hamed

82

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

83

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

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

84

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

85

Sharpening directivity of ultrasonic range sensor using multiple transmitters by different amplitude and pulse width method  

Microsoft Academic Search

It is necessary to increase detectable length of ultrasonic range sensor for autonomous land vehicles. This means that we must radiate the powerful ultrasonic waves whose directivity is sharp. However sound waves have the characteristic that small attenuation in propagation and sharp directivity are incompatible with each other. In order to decrease attenuation rate for distance, the authors used multiple

Masayuki Hiyama; Takashi Emura; Masaaki Kumagai

1997-01-01

86

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

87

[An experimental and clinical study on the dissecting aortic aneurysm--usefulness of magnetic resonance imaging and the ultrasonic pulsed Doppler duplex system].  

PubMed

In the treatment of dissecting aortic aneurysm, it is important to understand the exact conditions of the disease. For this purpose Aortography (AOG) and X-ray computerized tomography (CT) have been used. Magnetic Resonance Imaging (MRI) and the ultrasonic pulsed Doppler duplex system are completely non-invasive and may be used instead of AOG and CT. Experimental aortic dissection was done surgically using modified Blanton's method in 8 mongrel dogs. MRI and the ultrasonic pulsed Doppler duplex system were used on these dogs before and after surgery which consisted of surgical closure of entry and insertion of Ivalon Sponge to false lumen. MRI patterns were classified into three: i.e., low, middle, and high intensity. The ultrasonic pulsed Doppler duplex system patterns were classified into four: i.e., normal flow, to and fro, turbulent flow and wall motion patterns respectively. These patterns of MRI and the ultrasonic pulsed Doppler duplex system were closely correlated to autopsy findings. These results indicated that MRI and the ultrasonic pulsed Doppler duplex system are useful to evaluate the changes of figures and hemodynamics of the false lumen. In the clinical study, MRI was performed on 26 patients of dissecting aortic aneurysm before and after surgery. These results were compared with those of AOG and CT. In the detection of the intimal flap, the main arterial branches, and the location of the entry and reentry, MRI was superior to CT and almost equal to AOG. PMID:2961672

Simizu, M

1987-09-01

88

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

89

Analysis of chirped-pulse-amplification system based on Offner triplet stretcher and transmission grating compressor  

NASA Astrophysics Data System (ADS)

Analytical phase expressions are presented for an Offner stretcher and transmission grating compressor based on ray tracing and apply them to analyze a chirped-pulse-amplification (CPA) system. Besides, an optimization method to extract high-fidelity amplified pulse is proposed by controlling the phase of the entire system. Through theoretical analysis and numerical simulation, one can adjust the incident angle and perpendicular distance between gratings to completely compensate dispersion of Offner stretcher over entire wavelength. Finally, the optimized CPA system provides Fourier-transform-limit pulse which is identical with seed pulse.

Li, Lin; Li, Chaoming; Chen, Xinrong; Liu, Linyue; Wu, Jianhong

2014-11-01

90

High pulse repetition frequency, multiple wavelength, pulsed CO(2) lidar system for atmospheric transmission and target reflectance measurements.  

PubMed

A multiple wavelength, pulsed CO(2) lidar system operating at a pulse repetition frequency of 200 Hz and permitting the random selection of CO(2) laser wavelengths for each laser pulse is presented. This system was employed to measure target reflectance and atmospheric transmission by using laser pulse bursts consisting of groups with as many as 16 different wavelengths at a repetition rate of 12 Hz. The wavelength tuning mechanism of the transversely excited atmospheric laser consists of a stationary grating and a flat mirror controlled by a galvanometer. Multiple wavelength, differential absorption lidar (DIAL) measurements reduce the effects of differential target reflectance and molecular absorption interference. Examples of multiwavelength DIAL detection for ammonia and water vapor show the dynamic interaction between these two trace gases. Target reflectance measurements for maple trees in winter and autumn are presented. PMID:20725406

Ben-David, A; Emery, S L; Gotoff, S W; D'Amico, F M

1992-07-20

91

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

92

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

93

Reflection and Transmission of Pulsed Electromagnetic Fields through Multilayered  

E-print Network

explored possible health effects of pulsed, low-level phased-array radio fre- quency energy exposure due impor- tant questions regarding the possible health effects of such non-ionizing radiation, describing-ionizing radiation is harmless below ex- posure levels where heating first occurs [1]. How- ever, this result assumes

Oughstun, Kurt

94

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

95

The measurement of shear and compression waves in curing epoxy adhesives using ultrasonic reflection and transmission techniques simultaneously  

NASA Astrophysics Data System (ADS)

Thin epoxy resin adhesive samples were ultrasonically measured during cure using normal incidence radially polarized shear wave electromagnetic acoustic transducers (EMATs). The EMATs used generated predominantly SH shear waves but they also generated/detected compression waves allowing the simultaneous measurement of shear and compression wave propagation through a curing epoxy in a non-contact regime. The source of the compression wave generation has been determined to be the in-plane shear Lorentz force. The adhesive thickness examined in the experiments was approximately 1 mm, which was optimal for experimental measurement using our apparatus: it temporally separated the ultrasonic waves of interest from others present in the pulse whilst remaining thin enough to be representative of a realistic adhesive layer. The rapid cure and standard or 'longer' cure epoxy adhesives described in this paper were supplied in a two-part cartridge form. The experiments show that there is a fundamental difference between the way that the elastic moduli develop in the rapid cure and the longer cure time epoxies. The rapid cure epoxy initially developed a shear elastic modulus at a fast rate, which suddenly decreased at approximately the same time that the temperature of the adhesive reached its maximum value during the exothermic reaction. The reflection measurements show that there was significant coupling of the shear wave into the adhesive even in its initial liquid-like state. The ultrasonic shear and compression wave velocities of the epoxy were calculated from the very outset of the cross-linking reaction using the reflection technique. A transmitted compression wave was visible from the outset of cure, and once a transmitted shear wave was detectable it was possible to measure attenuation for both; however, these data are not presented here as they are not key to the paper and they can be found in our previous publications that are referenced in this one.

Dixon, S.; Jaques, D.; Palmer, S. B.; Rowlands, G.

2004-05-01

96

Detection of crack growth in concrete from ultrasonic intensity measurements  

Microsoft Academic Search

Results of monitoring crack growth in concrete during uniaxial compression using ultrasonic methods offer the possibility\\u000a of determining the internal properties of a concrete member both during and after loading without causing any damage. The\\u000a ultrasonic transducers were designed to monitor pulse transmission in both the axial and lateral directions throughout a uniaxial\\u000a compression test. The waveforms received at various

Wimal Suaris; Viraj Fernando

1987-01-01

97

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

98

Pulse Transmission across a Single Optical Ring-Resonator with Negative Group Velocity: Theory and Experiment  

Microsoft Academic Search

We study pulse transmission across a single optical ring-resonator circuit theoretically. The theory is supported by experimental measurements. From the study, we discuss intuitively the fulfillment of the causality rules in negative delay phenomenon, which occurs when the circuit possesses a negative group velocity.

H. P. Uranus; L. Zhuang; C. G. H. Roeloffzen; H. J. W. M. Hoekstra

2008-01-01

99

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

100

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

101

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

NASA Technical Reports Server (NTRS)

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

Kishonio, D.; Heyman, J. S.

1985-01-01

102

LABORATORY INVESTIGATION Influences of Microbubble Diameter and Ultrasonic  

E-print Network

LABORATORY INVESTIGATION Influences of Microbubble Diameter and Ultrasonic Parameters on In Vitro ultrasonic parameters on in vitro sonothrombolysis (ultrasound [US]-mediated thrombolysis) efficacy as functions of MB size and concentration, ultrasonic frequency and intensity, pulse duration (PD), pulse

Illinois at Urbana-Champaign, University of

103

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

E-print Network

THz Pulse Transmission Through the Atmosphere Yihong Yang, Student Member, IEEE, Mahboubeh Mandehgar of repetitive broadband THz pulses the record distance of 167 m through the atmosphere with 51% relative in the output pulse structure is composed of phase-locked frequency components extending from 0.07 to 0.37 THz

Oklahoma State University

104

Angle-dependent ultrasonic transmission through plates with subwavelength hole arrays.  

PubMed

We study the angle and frequency dependence of sound transmission through water-immersed perforated aluminum plates. Three types of resonances are found to govern the acoustic properties of the plates: lattice resonances in periodic arrays, Fabry-Perot modes of the hole cavities, and elastic Lamb modes. The last two of them are still present in random arrays and have no parallel in optical transmission through holes. These modes are identified by comparing experiment with various levels of theoretical analysis, including full solution of the elasto-acoustic wave equations. We observe strong mixture of different transmission mechanisms, giving rise to unique acoustic behavior and opening new perspectives for exotic wave phenomena. PMID:19392441

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

2009-04-10

105

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

NASA Technical Reports Server (NTRS)

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

Kishoni, D.; Heyman, J. S.

1986-01-01

106

Measurement of ultrasonic velocity with improved accuracy in pulse echo setup.  

PubMed

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. PMID:17764352

Rajagopalan, S; Sharma, S J; Dubey, P K

2007-08-01

107

Ultrasonic backscatter and transmission parameters at the os calcis in postmenopausal osteoporosis.  

PubMed

Ultrasound technology has emerged as a new tool in the assessment of osteoporosis. Ultrasound parameters usually are measured in transmission; there is a potential for the analysis of backscattered signals to provide information on bone microarchitecture. The aim of this study was to explore a new technological development of the method, adding backscatter coefficient to transmission parameters, and to examine the appropriate thresholds to identify postmenopausal osteoporotic women. We examined 210 postmenopausal women (including 60 with osteoporotic fractures) and 30 healthy premenopausal controls. They had lumbar spine and hip bone mineral density (BMD) measurement and quantitative ultrasound (QUS) evaluation at the os calcis, measured in transmission (broadband ultrasound attenuation [BUA], speed of sound [SOS], ratio of transit time [dt] to BUA [dt/BUA], and "strength" index [STI]) and reflexion (broadband ultrasound backscattering [BUB]). The standardized CVs (sCVs) were between 2.27 % and 3.40 % for QUS measured in transmission and 4.41% for BUB. The odds ratio (OR) for fracture discrimination adjusted for age was 2.77 for hip BMD and between 1.6 and 2.9 for QUS. After adjustment for hip BMD, ORs were still highly significant for SOS, STI, and dt/BUA. According to hip BMD T score, prevalence of osteoporosis in our population was 39%. To detect the same prevalence, T scores ranged between -0.95 and -1.42 for QUS. QUS parameters have adequate ability to discriminate osteoporotic patients from controls. The World Health Organization (WHO) threshold for diagnosis of osteoporosis does not apply to this technology. The clinical utility of BUB at the os calcis, in addition to usual ultrasound parameters, is not yet proven. However, BUB evaluation, which does not require two transducers and may be implemented in conventional reflection mode systems, warrants further studies. PMID:11450712

Roux, C; Roberjot, V; Porcher, R; Kolta, S; Dougados, M; Laugier, P

2001-07-01

108

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

2003-08-22

109

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

110

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

111

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

PubMed

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

Le, L H

1998-08-01

112

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

2014-01-01

113

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

114

Measurement of local pulse wave velocity in arteriosclerosis by ultrasonic Doppler method  

Microsoft Academic Search

This paper presents a new method to measure local pulse wave velocity (PWV), which is an index of the hardness in the range of several millimeters on the aortic wall for diagnosis of the early stage arteriosclerosis. Small vibration signals are measured simultaneously at two adjacent points on the aortic wall near the aortic valve by electronically alternating the direction

N. Chubachi; H. Kanai; R. Murata; Y. Koiwa

1994-01-01

115

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

116

Dispersion-free fiber transmission for femtosecond pulses by use of a dispersion-compensating fiber and a programmable pulse shaper.  

PubMed

We demonstrate nearly distortionless 2.5-km fiber transmission of sub-500-fs pulses, using a combination of standard single-mode fiber, dispersion-compensating fiber, and a programmable pulse shaper for simultaneous quadratic and cubic dispersion compensation. The dispersion-compensating fiber corrects the bulk of the quadratic and the cubic phases for the single-mode fiber, and the fiber-pigtailed programmable pulse shaper exactly compensates the residual dispersion terms. Together these elements permit complete recompression of pulses, which first broaden by ~400 times in the single-mode fiber. PMID:18084486

Chang, C C; Sardesai, H P; Weiner, A M

1998-02-15

117

Ultrasonic Study of Machinable Ceramic over Temperature Range from Room Temperature to 1000°C  

NASA Astrophysics Data System (ADS)

Shear and compressional velocities and the attenuation of a 0.5 MHz ultrasonic wave in a machinable ceramic were accurately measured by the pulse transmission method over the temperature range from 30°C to 1000°C. The temperature dependence of the compressional and shear wave velocities and attenuation exhibits a marked feature around the glass transition temperature. The temperature dependence of the elastic modulus was calculated from the ultrasonic data. The elastic properties of the machinable ceramic at high temperatures are shown.

Kashiwagura, Nobuo; Akita, Masayuki; Kamioka, Hiroaki

2005-06-01

118

The effect of stress on ultrasonic pulses in fiber reinforced composites  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

119

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

120

On the validity and improvement of the ultrasonic pulse-echo immersion technique to measure real attenuation.  

PubMed

A fundamental assumption embraced in conventional use of the ultrasonic pulse-echo immersion technique to measure attenuation in solid materials is revisited. The cited assumption relies on perfect and immutable adhesion at the water to sample interface, a necessary condition that allows calculating the reflection coefficient at any interface from elastic wave propagation theory. This parameter is then used to correct the measured signal and obtain the real attenuation coefficient of the sample under scrutiny. In this paper, cases in which the perfectly cohesive interfacial condition is not satisfied are presented. It is shown also that in those cases, the repeatability of the conditions at the interface is always uncertain. This implies that the reflection coefficients are unknown, even when density is known. A new method of simultaneously measuring the reflection coefficients for both exposed interfaces that are normal to the transducer, and the attenuation coefficient of the specimen is developed and is presented here. The robustness of the new method is proven, as we demonstrate that the proper value of attenuation is achieved independently of the continuously varying interfacial conditions of these non-ideal cases. PMID:23998204

Goñi, Miguel A; Rousseau, Carl-Ernst

2014-02-01

121

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

SciTech Connect

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

Blouin, A.; Carrion, L.; Padioleau, C.; Bouchard, P.; Monchalin, J.-P. [Industrial Materials Institute, National Research Council of Canada, 75 de Mortagne Blvd., Boucherville, Quebec, J4B 6Y4 (Canada)

2005-04-09

122

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

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

123

Ultrasonic wave generation by pulsed microwaves applied to non contact NDT of materials  

NASA Astrophysics Data System (ADS)

The non-destructive testing possibilities of the acoustic wave generation in a viscoelastic plate irradiated by pulsed microwaves is presented. Absorbed microwave energy cause thermoelastic expansion that radiates acoustic waves in air A capacitive air-coupled transducer records the time-domain amplitude of the acoustic resonance of the plates. A linear scanning yield defect imaging of holes or metallic inserts, and the influence of bad/good interface was preliminary investigated.

Guilliorit, Emmanuel; Hosten, Bernard; Bacon, Christophe

2001-04-01

124

Ultrasonic meters measure gas pipeline flow  

SciTech Connect

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

NONE

1995-04-01

125

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. PMID:22356771

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

2013-01-01

126

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

PubMed

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

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

2013-05-20

127

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

128

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

SciTech Connect

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

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

1991-10-01

129

Ultrasonic bone densitometer  

NASA Technical Reports Server (NTRS)

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

Hoop, J. M. (inventor)

1974-01-01

130

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

PubMed

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

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

2014-03-01

131

Nondestructive ultrasonic measurement of bolt preload using the pulsed-phase locked-loop interferometer  

NASA Technical Reports Server (NTRS)

Achieving accurate preload in threaded fasteners is an important and often critical problem which is encountered in nearly all sectors of government and industry. Conventional tensioning methods which rely on torque carry with them the disadvantage of requiring constant friction in the fastener in order to accurately correlate torque to preload. Since most of the applied torque typically overcomes friction rather than tensioning the fastener, small variations in friction can cause large variations in preload. An instrument called a pulsed phase locked loop interferometer, which was recently developed at NASA Langley, has found widespread use for measurement of stress as well as material properties. When used to measure bolt preload, this system detects changes in the fastener length and sound velocity which are independent of friction. The system is therefore capable of accurately establishing the correct change in bolt tension. This high resolution instrument has been used for precision measurement of preload in critical fasteners for numerous applications such as the space shuttle landing gear and helicopter main rotors.

Allison, S. G.; Heyman, J. S.

1985-01-01

132

Brachial vs. central systolic pressure and pulse wave transmission indicators: a critical analysis.  

PubMed

This critique is intended to provide background for the reader to evaluate the relative clinical utilities of brachial cuff systolic blood pressure (SBP) and its derivatives, including pulse pressure, central systolic pressure, central augmentation index (AI), and pulse pressure amplification (PPA). The critical question is whether the newer indicators add sufficient information to justify replacing or augmenting brachial cuff blood pressure (BP) data in research and patient care. Historical context, pathophysiology of variations in pulse wave transmission and reflection, issues related to measurement and model errors, statistical limitations, and clinical correlations are presented, along with new comparative data. Based on this overview, there is no compelling scientific or practical reason to replace cuff SBP with any of the newer indicators in the vast majority of clinical situations. Supplemental value for central SBP may exist in defining patients with exaggerated PPA ("spurious systolic hypertension"), managing cardiac and aortic diseases, and in studies of cardiovascular drugs, but there are no current standards for these possibilities. PMID:25233859

Izzo, Joseph L

2014-12-01

133

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

134

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

135

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

NASA Astrophysics Data System (ADS)

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

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

1992-02-01

136

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

137

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

138

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

139

Nonlinear transmission and reflection of ultrashort laser pulses by a thin semiconductor film under two-photon generation of biexcitons.  

PubMed

The transmission and reflection of an ultrashort laser pulse by a thin semiconductor film under the conditions of resonance excitation of biexcitons by two photons are theoretically investigated. The numerical solutions of the macroscopic equations are found for various values of the film thickness, the detuning from the two-photon resonance, the laser pulse duration, and the intensity. These equations have been obtained in the framework of the generalized bipolariton model. In this model a biexciton is formed from virtual excitons of four kinds and only some of them interact with the light. It is shown that the thin film substantially transforms the incident pulse. For specific conditions, high and narrow transmission and reflection peaks can appear, or even trains of such peaks. In some cases their height can considerably exceed the amplitude of the incident pulse. The results are compared with similar results obtained on the basis of other models. PMID:21572228

Beloussov, Igor V; Khadzhi, Peter I; Corovai, Alexander V; Markov, Dmitri A

2011-06-01

140

High Spatial Resolution Fast-Neutron Imaging Detectors for Pulsed Fast-Neutron Transmission Spectroscopy  

E-print Network

Two generations of a novel detector for high-resolution transmission imaging and spectrometry of fast-neutrons are presented. These devices are based on a hydrogenous fiber scintillator screen and single- or multiple-gated intensified camera systems (ICCD). This detector is designed for energy-selective neutron radiography with nanosecond-pulsed broad-energy (1 - 10 MeV) neutron beams. Utilizing the Time-of-Flight (TOF) method, such a detector is capable of simultaneously capturing several images, each at a different neutron energy (TOF). In addition, a gamma-ray image can also be simultaneously registered, allowing combined neutron/gamma inspection of objects. This permits combining the sensitivity of the fast-neutron resonance method to low-Z elements with that of gamma radiography to high-Z materials.

Mor, I; Bar, D; Feldman, G; Goldberg, M B; Katz, D; Sayag, E; Shmueli, I; Cohen, Y; Tal, A; Vagish, Z; Bromberger, B; Dangendorf, V; Mugai, D; Tittelmeier, K; Weierganz, M

2009-01-01

141

Parametric tunable dispersion compensation for the transmission of sub-picosecond pulses.  

PubMed

Parametric tunable dispersion compensator (P-TDC), which allows format-independent operation owing to seamlessly wide bandwidth, is expected to be one of the key building blocks of the future ultra-high speed optical network. In this paper, a design of ultra-wide band P-TDC is presented showing that bandwidth over 2.5 THz can be achieved by compensating the chromatic dispersion up to the 4th order without employing additional method. In order to demonstrate the potential application of P-TDC in the Tbit/s optical time division multiplexing transmissions, 400 fs optical pulses were successfully transmitted through a dispersion managed 6-km DSF fiber span. PMID:21934918

Kurosu, Takayuki; Tanizawa, Ken; Petit, Stephane; Namiki, Shu

2011-08-01

142

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

143

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

PubMed

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

Kaatze, U; Scholle, F D

1990-09-01

144

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

145

Ultrasonic Monitor  

NASA Technical Reports Server (NTRS)

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

1983-01-01

146

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

Microsoft Academic Search

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

Shin-nosuke Suzuki; Tamotsu Katane; Osami Saito

2003-01-01

147

Video Ultrasonics by Pulsed TV Holography: A New Capability for Non-Destructive Testing of Shell Structures  

Microsoft Academic Search

We present a novel capability of the TV holography technique applied to the non-destructive testing of mechanical parts or structures with the form of a plate or a shell, which consists of the recording of high quality synthetic movies of the spatio-temporal evolution of instantaneous ultrasonic displacement fields of the surface under inspection. Moreover, in the case of narrowband acoustic

José Luis Fernández; Cristina Trillo; J. Luis Deán; José Carlos López

2007-01-01

148

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

PubMed

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

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

2003-01-01

149

Structure of virioplankton in the Charente Estuary (France): transmission electron microscopy versus pulsed field gel electrophoresis.  

PubMed

Changes in the composition of viral communities were investigated along a salinity gradient and at different times by means of transmission electron microscopy (TEM) and pulsed field gel electrophoresis (PFGE). Samples were collected in fresh (Charente River), estuarine (Charente Estuary), and coastal (Pertuis d'Antioche, French Atlantic coast) waters. Both methods revealed similar patterns in viral community structure with a dominance of small viral particles (capsid and genome size). Viruses with a head size below 65 nm made up 71 +/- 5% of total virus-like particles, and virus-like genomes (VLG) below 100 kb accounted for 89 +/- 9% of total VLG. Despite this apparent stability of virioplankton composition over spatial scale (salinity gradient), the occurrence of large viruses (capsid and genome size) in estuarine and seawater samples indicated the presence of viral populations specific to a geographical location. Temporal changes in the structure (capsid and genome size) of viral communities were more pronounced than those reported at the spatial scale. From January to May 2003, seasonal changes in viral abundance and bacterial production occurred concomitantly with an increase in viral genomic diversity (richness), suggesting that virioplankton composition was strongly linked to changes in microbial activity and/or in the structure of the host communities. Although PFGE and TEM yielded complementary results in the description of virioplankton structures, it seems that the use of PFGE alone should be enough for the monitoring of community changes. PMID:16463133

Auguet, J C; Montanié, H; Lebaron, P

2006-02-01

150

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

PubMed

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

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

2014-01-01

151

Ultrasonic determination of recrystallization  

NASA Technical Reports Server (NTRS)

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

Generazio, E. R.

1986-01-01

152

Ultrasonic ranging control system for industrial robots  

SciTech Connect

An ultrasonic ranging control system is described for a robot having a movable arm. The system comprises: an ultrasonic transducer array for transmitting an acoustical pulse and for detecting a reflected echo; transducer array is mounted proximate to the distal end of the movable arm so as to be arcuately pivotable in both a horizontal and vertical direction; the ultrasonic transducer array includes ultrasonic transducers arrayed in an angularly manner to emulate a single transducer with a wide transmit and receive pattern in substantially the horizontal plane; each transducer has an individual beam width of approximately 10 degrees to each side; the individual transducers are arranged arcuately about a horizontal plane approximately 20 degrees apart with a quantity of five such transducers; a horizontal beam width of approximately 100 degrees is attained; and circuit means for measuring the elapsed time between initial transmission and echo detection by the transducer array and for providing an output signal indicative of the elapsed time and for conversion of elapsed time to a signal representative of distance;

Caughman, D.O.; Plumley, W.J.

1987-06-16

153

Ringing in the Pulse Response of Long and Wideband Coaxial Transmission Lines due to Group Delay Dispersion  

E-print Network

In particle accelerators coaxial cables are commonly used to transmit wideband beam signals covering many decades of frequencies over long distances. Those transmission lines often have a corrugated outer and/or inner conductor. This particular construction exhibits a significant amount of frequency dependent group delay variation. A comparison of simulations based on theoretical models and S11 and S21 network analyzer measurements up to 2.5 GHz is presented. It is shown how the non-linear phase response and varying group delay leads to ringing in the pulse response and subsequent distortion of signals transmitted through such coaxial transmission lines.

Kotzian, G; Federmann, S; Höfle, Wolfgang; Kotzian, G; de Maria, R

2010-01-01

154

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

SciTech Connect

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

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

2009-05-04

155

Photonic generation and wireless transmission of different pulse modulation formats for high-speed impulse radio ultrawideband over fiber systems  

NASA Astrophysics Data System (ADS)

Novel methods on photonic generation of different pulse modulation formats for impulse radio ultra-wideband (IR-UWB) over fiber application is overviewed. A flexible, high-speed and power-efficient photonic on-off keying and binary phase shift keying modulated IR-UWB over fiber communication system is proposed and demonstrated. IR-UWB transmission over 20km fiber and 0.25m wireless link without any compensation is presented. The transmission performance for both modulation formats is evaluated and compared by measuring eye diagrams and the electrical spectra.

Xie, Shizhong; Chen, Hongwei; Chen, Minghua; Yang, Sigang; Li, Pengxiao

2011-12-01

156

Ultrasonic ranging control system for industrial robots  

Microsoft Academic Search

An ultrasonic ranging control system is described for a robot having a movable arm. The system comprises: an ultrasonic transducer array for transmitting an acoustical pulse and for detecting a reflected echo; transducer array is mounted proximate to the distal end of the movable arm so as to be arcuately pivotable in both a horizontal and vertical direction; the ultrasonic

D. O. Caughman; W. J. Plumley

1987-01-01

157

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

SciTech Connect

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

Yalin, Azer P; Joshi, Sachin

2014-06-03

158

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

159

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

SciTech Connect

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

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

2005-06-01

160

Ultrasonic evaluation of high voltage circuit boards  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

161

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

E-print Network

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

Chen, Kailiang

162

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

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

163

Ultrasonic Wave Generation by Lasers on Different Metal Surfaces  

Microsoft Academic Search

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

S. E. Kruger; M. Lord

2007-01-01

164

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

165

Multi-frequency axial transmission bone ultrasonometer.  

PubMed

The last decade has seen a surge in the development of axial transmission QUS (Quantitative UltraSound) technologies for the assessment of long bones using various modes of acoustic waves. The condition of cortical bones and the development of osteoporosis are determined by numerous mechanical, micro-structural, and geometrical or macro-structural bone properties like hardness, porosity and cortical thickness. Such complex manifestations of osteoporosis require the evaluation of multiple parameters with different sensitivities to the various properties of bone that are affected by the disease. This objective may be achieved by using a multi-frequency ultrasonic examination The ratio of the acoustic wavelength to the cortical thickness can be changed by varying the frequency of the ultrasonic pulse propagating through the long bone that results in the change in composition of the induced wave comprised of a set of numerous modes of guided, longitudinal, and surface acoustic waves. The multi-frequency axial transmission QUS method developed at Artann Laboratories (Trenton, NJ) is implemented in the Bone Ultrasonic Scanner (BUSS). In the current version of the BUSS, a train of ultrasonic pulses with 60, 100, 400, 800, and 1200 kHz frequencies is used. The developed technology was tested on a variety of bone phantoms simulating normal, osteopenic, and osteoporotic bones. The results of this study confirm the feasibility of the multi-frequency approach for the assessment of the processes leading to osteoporosis. PMID:24206675

Tatarinov, Alexey; Egorov, Vladimir; Sarvazyan, Noune; Sarvazyan, Armen

2014-07-01

166

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

167

Real time acquisition and PC to PC wireless transmission of human carotid pulse waveform  

Microsoft Academic Search

Carotid pulse is an established physiological parameter used to deduce cardiac information. Technological advances allow non-invasive measurement of carotid waveform, but involve complex electronics. Simple and relatively inexpensive method is devised here to acquire the carotid pulse. Measurements were made non-invasively on human subjects in various postures using piezoelectric sensor. Transducer output is interfaced directly to a computer in real

Dipali Bansal; Munna Khan; Ashok K. Salhan

2009-01-01

168

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

Microsoft Academic Search

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

J. R. Bernstein; J. B. Spicer

2000-01-01

169

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

Microsoft Academic Search

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

Johanna Rebecca Bernstein

1999-01-01

170

Transmission zerocrossings  

E-print Network

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

Chen, Sheng

171

Multilevel signaling and pulse shaping for spectrum efficiency in subcarrier multiplexing transmission  

Microsoft Academic Search

Subcarrier multiplexing (SCM) transmission has been widely used for analog video transmission in CATV systems. As digital video technology rapidly advances, there is a strong need to transmit digital video over the same SCM system. Since digital video such as HDTV requires a much larger bandwidth, multilevel signaling becomes an important approach. As the number of levels increases, however, the

Ming-Kang Liu; Panayiotis C. Modestou

1994-01-01

172

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

PubMed

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

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

2010-03-29

173

Real time acquisition and PC to PC wireless transmission of human carotid pulse waveform.  

PubMed

Carotid pulse is an established physiological parameter used to deduce cardiac information. Technological advances allow non-invasive measurement of carotid waveform, but involve complex electronics. Simple and relatively inexpensive method is devised here to acquire the carotid pulse. Measurements were made non-invasively on human subjects in various postures using piezoelectric sensor. Transducer output is interfaced directly to a computer in real time and carotid wave is viewed successfully on virtual oscilloscope. Stored data is digitally filtered, visually analyzed and transferred wirelessly from one computer to another using windows hyper-terminal and XBee RF transceiver module. Automated analysis algorithm can be further developed. PMID:19674740

Bansal, Dipali; Khan, Munna; Salhan, Ashok K

2009-10-01

174

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

175

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

NASA Astrophysics Data System (ADS)

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

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

2002-11-01

176

Ultrasonic Imaging Of Deep Arteries  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

177

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

Microsoft Academic Search

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

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

178

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. PMID:22866236

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

2011-01-01

179

Cost efficient pulse source for return-to-zero differential phase shift keyed transmission systems  

Microsoft Academic Search

It is anticipated that future long-haul lightwave transport networks will be required to exhibit multi-Tb\\/s capacities. High-speed transmission systems employing advanced modulation formats like RZ DPSK in conjunction with balanced detection have shown superior performance in terms of extended reach (better receiver sensitivity) and by offering better immunity to dispersion and\\/or nonlinear impairments. Key factors in the acceptance and deployment

P. M. Anandarajah; L. P. Barry

2009-01-01

180

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

PubMed

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

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

2014-01-01

181

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

PubMed Central

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

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

2014-01-01

182

Ultrasonic Velocity and Density Measurement of Liquid Bi-Ga Alloys with Miscibility Gap Region  

NASA Astrophysics Data System (ADS)

The measurement of ultrasonic velocity and sound attenuation, and density has been carried out for several liquid Bi-Ga alloys from the melting points to about 800°C. The ultrasonic velocity and its attenuation were determined by means of an ultrasonic pulse transmission method and the density was determined by a ?-ray absorption method. The adiabatic compressibility and molar volume of this system are obtained by the observed sound velocity and density. The temperature coefficient of the adiabatic compressibility is rather small in the concentration above the miscibility gap region than in the other concentration. The thermodynamic properties of this system are discussed based on the correlation between the structure and the compressibility.

Inui, Masanori; Takeda, Shin'ichi; Uechi, Tetsuo

1992-09-01

183

Time Reversal Beam Focusing of Ultrasonic Array Transducer on a Defect in a Two Layer Medium  

NASA Astrophysics Data System (ADS)

The ability of time reversal techniques to focus ultrasonic beams on the source location is important in many aspects of ultrasonic nondestructive evaluation. In this paper, we investigate the time reversal beam focusing of ultrasonic array sensors on a defect in layered media. Numerical modeling is performed using the commercially available software which employs a time domain finite difference method. Two different time reversal approaches are considered—the through transmission and the pulse-echo. Linear array sensors composed of N elements of line sources are used for signal reception/excitation, time reversal, and reemission in time reversal processes associated with the scattering source of a side-drilled hole located in the second layer of two layer structure. The simulation results demonstrate the time reversal focusing even with multiple reflections from the interface of layered structure. We examine the focusing resolution that is related to the propagation distance, the size of array sensor and the wavelength.

Jeong, Hyunjo; Lee, Jeong-Sik; Lee, Chung-Hoon

2010-02-01

184

Modeling Methods for the Main Switch of High Pulsed-Power Facilities Based on Transmission Line Code  

NASA Astrophysics Data System (ADS)

Based on the transmission line code (TLCODE), a circuit model is developed here for analyses of main switches in the high pulsed-power facilities. With the structure of the ZR main switch as an example, a circuit model topology of the switch is proposed, and in particular, calculation methods of the dynamic inductance and resistance of the switching arc are described. Moreover, a set of closed equations used for calculations of various node voltages are theoretically derived and numerically discretized. Based on these discrete equations and the Matlab program, a simulation procedure is established for analyses of the ZR main switch. Voltages and currents at different key points are obtained, and comparisons are made with those of a PSpice L-C model. The comparison results show that these two models are perfectly in accord with each other with discrepancy less than 0.1%, which verifies the effectiveness of the TLCODE model to a certain extent.

Hu, Yixiang; Zeng, Jiangtao; Sun, Fengju; Wei, Hao; Yin, Jiahui; Cong, Peitian; Qiu, Aici

2014-09-01

185

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

186

Blind multiridge detection for automatic nondestructive testing using ultrasonic signals.  

PubMed

Ultrasonic imaging has been a significant means for nondestructive testing (NDT). Recently the NDT techniques via the ultrasonic instrumentation have shown the striking capability of the quality control for the material fabrication industry. To the best of our knowledge, all existing signal processing methods require either the a priori information of the ultrasonic signature signals or the manual segmentation operation to achieve the reliable parameters that characterize the corresponding mechanical properties. In this paper, we first provide a general mathematical model for the ultrasonic signals collected by the pulse-echo sensors, then design a totally blind novel signal processing NDT technique relying on neither a priori signal information nor any manual effort. Based on the automatic selection of optimal frame sizes using a proposed new criterion in our scheme, the signature signal can be blindly extracted for further robust multiridge detection. The detected ridge information can be used to estimate the transmission and attenuation coefficients associated with any arbitrary material sample for the fabrication quality control. PMID:17036799

Wu, Hsiao-Chun; Gupta, Nikhil; Mylavarapu, Phani S

2006-10-01

187

Transmission properties of terahertz pulses through semiconductor split-ring resonators  

NASA Astrophysics Data System (ADS)

In this paper, two novel planar terahertz semiconductor split-ring resonators are successfully constructed and measured using the commercial software CST Microwave Studio. They exhibit a duel-band and a triple-band transmission property within the frequencies ranging from 0.1THz to 3THz. We have simulated the dual-band planar metamaterial with two distinct electric resonances at 0.81THz and 1.818THz, and triple-band planar metamaterial with three distinct electric resonances at 0.543THz, 1.044THz, and 1.506THz. These developments are further steps towards the development of broadband terahertz devices.

yun-hong, He; Jiu-sheng, Li

2011-02-01

188

Ultrasonic Infrared Thermal Wave Technology and Its Applications in  

Microsoft Academic Search

The ultrasonic infrared thermal wave method is a new nondestructive testing technique. It is remarkably sensitive and convenient for detection of small vertical cracks, such as fatigue cracks in metals. Pulses of ultrasonic launched by the ultrasonic emitter as heat source are excited into the sample, if there are some cracks in the material, they will be revealed through their

Dapeng CHEN; Cunlin ZHANG; Lichun FENG; Ning TAO; Xiaoli LI; Yanhong LI; Weichao XU

2008-01-01

189

An Authentication Protocol using Ultrasonic Ranging  

Microsoft Academic Search

This report presents a method for establishing and secur- ing spontaneous interactions on the basis of spatial references which are obtained by accurate sensing of relative device positions. Utilising the Relate ultrasonic sensing system, we construct an interlocked protocol using radio frequency messages and ultrasonic pulses for verifying that two devices share a secret. This verification is necessary to prevent

Rene Mayrhofer; Mike Hazas; Hans Gellersen

2006-01-01

190

Ultrasonic detecting and identifying of particulates  

SciTech Connect

A method of detecting and identifying particulates in the recirculating fluid flow for an oil recovery system by counting the number of ultrasonic pulses reflected from the particulates and comparing the number counted with the amount of attenuation of ultrasonic energy across the flow.

Abts, L.R.

1983-05-03

191

Evaluation of Amorphous Diffusion Bonding by Nonlinear Ultrasonic Method  

NASA Astrophysics Data System (ADS)

The characteristic of bond interface in amorphous diffusion bonding, of which evaluation is impossible by conventional method, was quantitatively evaluated by the second harmonic amplitude. Steel bars were bonded with Ni-based amorphous film. Conventional ultrasonic method, e.g. the echo height reflected from bond interface, could not identify samples manufactured at different bonding temperatures 1050, 1150 and 1250°C. Therefore, nonlinear ultrasonic method was applied for distinguishing the difference of bond strength. The nonlinear ultrasonic method is to measure the higher harmonics generated by nonlinear stress-strain relationship at weak bonds. Measurements were conducted in contact using piezoelectric transducers in through-transmission. The fundamental and second harmonic wave frequencies are 5 and 10 MHz. To measure second harmonic wave amplitude, a commercial superheterodyne receiver and pulse inversion method were used. The pulse inversion method is the digital signal processing to extract only second and even orders harmonic wave by superposing two burst waves with a 180° phase difference after corrected time-lag by cross-correlation function. These results were compared to destructive tests for examining the relationship between tensile strength and the second harmonics. Besides, elemental analysis by EPMA was performed for manifesting the source of second harmonics generation.

Ohara, Y.; Kawashima, K.; Yamada, R.; Horio, H.

2004-02-01

192

810 ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 44, no. 4, july 1997 Pulse-Echo Field Distribution Measurement  

E-print Network

810 ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 44, no. 4, july for spherically fo- cused transducers in the frequency range from 3 to 17 MHz, and a comparison with hydrophone

Illinois at Urbana-Champaign, University of

193

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

E-print Network

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

Ryan, Justin Mark

1986-01-01

194

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

E-print Network

Pulsed Terahertz Transmission Spectroscopy of Liquid CHCl3, CCl4, and their Mixtures B. N. Flanders 29, 1996X The frequency-dependent absorption coefficient of CHCl3, CCl4, and their mixtures, based on mole fraction weighted sums of the absorption coefficients of pure CHCl3 and CCl4, indicate

Scherer, Norbert F.

195

200 Gbit\\/s, 100km time-division-multiplexed optical transmission using supercontinuum pulses with prescaled PLL timing extraction and all-optical demultiplexing  

Microsoft Academic Search

A single channel, single polarisation 200 Gbit\\/s time-division-multiplexed optical transmission experiment is successfully demonstrated using optical short pulses generated by supercontinuum. A prescaled clock is recovered directly from the 200Gbit\\/s signal to drive an all-optical demultiplexer.

S. Kawanishi; H. Takara; T. Morioka; O. Kamatani; M. Saruwatari

1995-01-01

196

Using pulse width modulation for wireless transmission of neural signals in multichannel neural recording systems.  

PubMed

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- mum 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 approximately 2.56 Mb/s. PMID:19497823

Yin, Ming; Ghovanloo, Maysam

2009-08-01

197

NEW DESIGN AND ALGORITHM FOR AN ULTRASONIC PROPAGATION IMAGING SYSTEM  

Microsoft Academic Search

Laser-based ultrasonic sensing generally requires the probe to have a fixed focal length or to be contact. On the other hand, such a requirement is not essential in laser-based ultrasonic generation. Based on this point, we designed a pulsed laser-based ultrasonic propagation imaging (UPI) system which included developments of a tilting mirror system (TMS) for rapid ultrasonic scanning of target

Chen-Ciang CHIA; Jung-Ryul LEE; Jae-Sung PARK; Chang-Yong YUN; Jong Heon KIM

198

Segmented Motion Compensation for Complementary Coded Ultrasonic Imaging   

E-print Network

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

Cannon, Cormac; Hannah, John; McLaughlin, Steve

199

Ultrasonic Wave Generation by Lasers on Different Metal Surfaces  

NASA Astrophysics Data System (ADS)

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.

2007-03-01

200

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

PubMed

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

Kiani, Mehdi; Ghovanloo, Maysam

2015-02-01

201

Delamination detection in composites by laser ultrasonics  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

202

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

203

Ultrasonic transducer performance requirements, phase 3  

NASA Astrophysics Data System (ADS)

Simplified test methods are presented for assessing performace parameters of 5 and 10 MHz contact type ultrasonic transducers used in Air Force field and depot level nondestructive inspection. Ultrasonic transducer performance parameters covered are: Overall Appearance, Beam Exit Point, Beam Angle, Skew Angle, Beam Divergence Angle, Center Frequency, Pulse Length, Dead Zone, Signal-to-Noise Ratio, and Overall System Sensitivity. Requirements are given for the ultrasonic instrument to be used for the tests. The importance of maintaining an initial excitation pulse to certain specified conditions, such as a spike or single cycle bipolar spike with duration less than 0.5 mircrosec, to achieve uniformity and instrumentally unbiased test results is addressed, methods are also described for establishing a specified initial excitation pulse by adjusting control on the ultrasonic instrument.

Kwun, H.; Burkhadt, G. L.; Teller, C. M.

1981-08-01

204

2013 IEEE International Ultrasonics Symposium 21--25 July 2013, Prague  

E-print Network

2013 IEEE International Ultrasonics Symposium 21--25 July 2013, Prague Simultaneous Assessment of Bone Thickness and Velocity for Ultrasonic Computed Tomography Using Transmission-Echo Method Rui Zheng the cortical thickness and ultrasonic wave velocity for the mimic model of long bones. Keywords-- transmission

Boyer, Edmond

205

Nonlinear Ultrasonic Phased Array Imaging  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

206

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

PubMed

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

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

2014-11-20

207

Ultrasonic imaging of textured alumina  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

208

Pulse based sensor networking using mechanical waves through metal substrates  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

209

DGS diagrams used for tuning the sensitivity of the echo-pulse method of ultrasonic testing of railway rolling stock’s wheel-pair axles  

Microsoft Academic Search

Special features of DGS-diagram-based sensitivity tuning of the ultrasonic testing of railway rolling stock’s wheel-pair axles\\u000a through the use of normal and angle probes from the end and lateral surfaces are considered. The possibility of collecting\\u000a the reference signals by tuning with reference samples (without artificial reflectors of the “flat-bottom” type) was established.\\u000a Examples of flaw detection using tuning of

V. N. Danilov; V. N. Samokhvalov

2006-01-01

210

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

E-print Network

of a microwave probe up to 400 GHz.7 Also, the related and un- usual observations of guided ps pulse propagation. The transmitted pulses after propagating as much as 105 mm were measured at the end of the line mode propagation with very little group velocity dispersion. The experimentally derived values

211

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

DOEpatents

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

Maris, Humphrey J. (Barrington, RI)

2003-01-01

212

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

DOEpatents

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

Maris, Humphrey J. (Barrington, RI)

2002-01-01

213

Laser ultrasonic monitoring of ceramic sintering  

SciTech Connect

Noncontacting laser-ultrasonic measurements of the sintering of ceramics in real-time are described. Lasers are used for both generation and detection of ultrasonic waves propagating through the material. A pulsed laser generates the ultrasonic wave from thermoelastic absorption at the material surface. Detection is accomplished by a confocal Fabry--Perot interferometer, which is insensitive to the speckle nature of the scattered light from the sample surface and can obtain measurements from samples with rough or diffusely reflecting surfaces. The densification of the ceramic sample is determined by changes in the bulk longitudinal wave velocity and the sample shrinkage.

Telschow, K.L.; Walter, J.B.; Garcia, G.V. (Idaho National Engineering Laboratory, EG G Idaho, Incorporated, Idaho Falls, Idaho 83415-2209 (USA))

1990-12-15

214

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

NASA Astrophysics Data System (ADS)

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

Mutlu, Ilven; Ekinci, Sinasi; Oktay, Enver

2014-06-01

215

Piezoelectric Ultrasonic Micromotors  

E-print Network

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

Flynn, Anita M.

1995-06-01

216

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

217

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

NASA Astrophysics Data System (ADS)

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

Yu, Linxiao; Thompson, R. B.; Margetan, F. J.; Wang, Yurong

2004-02-01

218

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

E-print Network

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

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

2013-01-01

219

MEMS ultrasonic probe rotary scanning imaging system for medical endoscope  

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 the biopsy channel of an electronic endoscope and rotates it by a micro motor, acquiring fault histology features of digestive organs. Compared with external ultrasonic detection, the system reduces the distance between the transducer and the organ, diminishing the effects on imaging of fats and body cavity gas. On the basis of ultrasonic imaging system, this paper implements a pulse echo imaging system. We describe the ultrasonic probe, emission circuit, receiving circuit and protective circuit in detail. With the demodulation circuit, we get the amplitude of echo which indicates the objects. And to achieve the rotary scan, we design a synchronous control circuit and a data transfer circuit basing on the USB2.0 interface. Finally we get a grey image with 256 grey levels after coordinate conversion.

Chen, Xiaodong; Wen, Shijie; Yu, Daoyin

2006-11-01

220

Timing of the carotid arterial sounds in normal adult men: measurement of left ventricular ejection, pre-ejection period and pulse transmission time.  

PubMed

The first and second carotid arterial sounds (CaS1 and CaS2) were recorded simultaneously with the aortic valve echocardiogram, carotid pulse wave contour, heart sounds, and electrocardiogram in 27 healthy, normal subjects. The mean intervals between the onset of the QRS complex and the onsets of the first and second major components of the carotid arterial sounds were Q-CaS1 = 131 +/- 15 ms and Q-CaS2 = 412 +/- 36 ms, respectively. The mean delay of CaS1 after aortic valve opening was 43 +/- 6 ms, while the delay of CaS2 after aortic valve closure was 43 +/- 7 ms. The onset of CaS1 and CaS2 are exactly coincident with the upstroke and with the dicrotic notch of the carotid pulse wave contour. The recording of the carotid arterial sounds, heart sounds, and ECG has enabled us to measure systolic time intervals including the pre-ejection period, left ventricular ejection time, and pulse transmission time more easily than using the conventional method involving the carotid arterial pulse wave contour. The new approach provides accuracy and precision comparable to that of the previous methods. PMID:2070371

Hasegawa, M; Rodbard, D; Kinoshita, Y

1991-01-01

221

Non-crosstalk ultrasonic ranging system excited using chaotic sine frequency modulated sequences  

Microsoft Academic Search

Traditionally, most ultrasonic ranging systems are excited using pulse signals. A hardware platform of ultrasonic ranging system that is excited using a sine signal is presented. On the basis of the new hardware platform, the chaotic sine frequency modulation (CSFM) sequence is proposed to excite ultrasonic transducers. Correlation characteristics of the echo signals generated using the CSFM excitation sequences are

Yu-Long Song; Qing-Hao Meng; Jiao-Jiao Zhang; Ming Zeng

2011-01-01

222

Ultrasonic propagation in various gases at elevated pressures  

NASA Astrophysics Data System (ADS)

Ultrasonic propagation has been studied in air, helium (He) and carbon dioxide (CO2) at pressures of up to 2 bar. The experiments were carried out using an inexpensive pressure chamber, manufactured from commercially available components. Accurate measurements of ultrasonic attenuation were performed, taking into account the diffraction effects of the transducers. It is also shown that ultrasonic transmission through solid materials, such as cardboard, can be enhanced at high pressures, using capacitive transducers whose performance is enhanced under such conditions.

Choi, D. W.; Hutchins, D. A.

2003-06-01

223

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

SciTech Connect

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

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

2014-05-26

224

Measurement Interpretation and Uncertainty Resulting from Nonlinear Ultrasonic Wave Propagation  

Microsoft Academic Search

Nominally identical ceramic-element ultrasonic transducers, of the type used in the aerospace and metals industries for nondestructive evaluation (NDE), often have variability in the peak pressure of the generated ultrasonic pulses. The generated pressures are also high enough for nonlinear propagation to be present in the water medium, often used as coupling in these types of inspections. In this study,

J. A. Slotwinski

1999-01-01

225

High resolution measurements in liquid metal by focused ultrasonic wave  

Microsoft Academic Search

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

I. Ihara; C.-K. Jen; D. Ramos França

2000-01-01

226

Detection of Inclusion in Molten Metal by Focused Ultrasonic Wave  

Microsoft Academic Search

An attempt for detecting impurity particles suspended in molten zinc at 650°C has been made using a focused ultrasonic pulse-echo technique with a clad metallic buffer rod. The focused ultrasonic waves are generated by a spherical acoustic lens which is fabricated at the end of the buffer rod. An experiment is carried out at 10 MHz. The result shows that

Ikuo Ihara; Cheng-Kuei Jen; Demartonne Ramos França

2000-01-01

227

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

PubMed Central

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

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

2013-01-01

228

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

PubMed

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

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

2013-01-01

229

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

230

Ultrasonic techniques for aircraft ice accretion measurement  

NASA Technical Reports Server (NTRS)

Results of tests to measure ice growth in natural (flight) and artificial (icing wind tunnel) icing conditions are presented. Ice thickness is measured using an ultrasonic pulse-echo technique. Two icing regimes, wet and dry ice growth, are identified and the unique ultrasonic signal characteristics associated with these different types of ice growth are described. Ultrasonic measurements of ice growth on cylinders and airfoils exposed to artificial and natural icing conditions are presented. An accuracy of plus or minus 0.5 mm is achieved for ice thickness measurement using the pulse-echo technique. The performance of two-probe type ice detectors is compared to the surface mounted ultrasonic system. The ultrasonically measured ice accretion rates and ice surface condition (wet or dry) are used to compare the heat transfer characteristics for flight and icing wind tunnel environments. In general the heat transfer coefficient is inferred to be higher in the wind tunnel environment, not likely due to higher freestream turbulence levels. Finally, preliminary results of tests to measure ice growth on airfoil using an array of ultrasonic transducers are described. Ice profiles obtained during flight in natural icing conditions are shown and compared with mechanical and stereo image measurements.

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

1990-01-01

231

Absolute calibration technique for broadband ultrasonic transducers  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

232

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

233

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

234

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

NASA Technical Reports Server (NTRS)

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

Hammond, P. L.

1979-01-01

235

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

236

Noncontact Acousto-Ultrasonics for Material Characterization  

NASA Technical Reports Server (NTRS)

A NdYAG 1064 nm, laser pulse was employed to produce ultrasonic waves in specimens of SiC/SiC and SiC/Ti 6-4 composites which are high temperature materials of interest for aerospace applications. Air coupled transducers were used to detect and collect the signals used for acousto-ultrasonic analysis. Conditions for detecting ultrasonic decay signals were examined. The results were compared to those determined on the same specimens with contact coupling. Some non-contact measurements were made employing conventional air focused detectors. Others were performed with a more novel micromachined capacitance transducer. Concerns of the laser-in technology include potential destructiveness of the laser pulse. Repeated laser pulsing at the same location does lead to deterioration of the ultrasonic signal in some materials, but seems to recover with time. Also, unlike contact AU, the frequency regime employed is a function of laser-material interaction rather than the choice of transducers. Concerns of the air coupled-out technology include the effect of air attenuation. This imposes a practical upper limit to frequency of detection. In the case of the experimental specimens studied ultrasonic decay signals could be imaged satisfactorily.

Kautz, Harold E.

1998-01-01

237

Ultrasonic hydrometer  

DOEpatents

The disclosed ultrasonic hydrometer determines the specific gravity (density) of the electrolyte of a wet battery, such as a lead-acid battery. The hydrometer utilizes a transducer that when excited emits an ultrasonic impulse that traverses through the electrolyte back and forth between spaced sonic surfaces. The transducer detects the returning impulse, and means measures the time "t" between the initial and returning impulses. Considering the distance "d" between the spaced sonic surfaces and the measured time "t", the sonic velocity "V" is calculated with the equation "V=2d/t". The hydrometer also utilizes a thermocouple to measure the electrolyte temperature. A hydrometer database correlates three variable parameters including sonic velocity in and temperature and specific gravity of the electrolyte, for temperature values between 0.degree. and 40.degree. C. and for specific gravity values between 1.05 and 1.30. Upon knowing two parameters (the calculated sonic velocity and the measured temperature), the third parameter (specific gravity) can be uniquely found in the database. The hydrometer utilizes a microprocessor for data storage and manipulation. The disclosed modified battery has a hollow spacer nub on the battery side wall, the sonic surfaces being on the inside of the nub and the electrolyte filling between the surfaces to the exclusion of intervening structure. An accessible pad exposed on the nub wall opposite one sonic surface allows the reliable placement thereagainst of the transducer.

Swoboda, Carl A. (Naperville, IL)

1984-01-01

238

Ultrasonic hydrometer  

SciTech Connect

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

Swoboda, C.A.

1984-04-17

239

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

240

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

241

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

242

Wireless Transmission of EMG Signal and Analysis of Its Correlation with Simultaneously Acquired Carotid Pulse Wave Using Dual Channel System  

Microsoft Academic Search

The paper represents work on the challenge of real time, non-invasive simultaneous acquisition and wireless transmission of human physiological parameters using easy and cost effective approach. Electromyograph (EMG) signal detection and analysis is utilized in various clinical and biomedical applications including generation of control signal for prosthetic tools. However, better solutions to obtain noise free signal using compact detection arrangement

Dipali Bansal; Munna Khan; Ashok Kumar Salhan

2010-01-01

243

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

Microsoft Academic Search

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

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

2006-01-01

244

Experimental characterization and modeling for the growth rate of oxide coatings from liquid solutions of metalorganic precursors by ultrasonic pulsed injection in a cold-wall low-pressure reactor  

NASA Astrophysics Data System (ADS)

Several years ago, a method for depositing ceramic coatings called the Pulsed-MOCVD system was developed by the Raj group at Cornell University in association with Dr. Harvey Berger and Sono-Tek Corporation. The process was used to produce epitaxial thin films of TiO2 on sapphire substrates under conditions of low pressure, relatively high temperature, and very low growth rate. The system came to CU-Boulder when Professor Raj moved here in 1997. It is quite a simple technique and has several advantages over typical CVD systems. The purpose of this dissertation is two-fold; (1) understand the chemical processes, thermodynamics, and kinetics of the Pulsed-MOCVD technique, and (2) determine the possible applications by studying the film structure and morphology over the entire range of deposition conditions. Polycrystalline coatings of ceramic materials were deposited on nickel in the low-pressure, cold-wall reactor from metalorganic precursors, titanium isopropoxide, and a mixture of zirconium isopropoxide and yttria isopropoxide. The process utilized pulsed liquid injection of a dilute precursor solution with atomization by ultrasonic nozzle. Thin films (less than 1mum) with fine-grained microstructure and thick coatings (up to 1mum) with columnar-microstructure were deposited on heated metal substrates by thermal decomposition of a single liquid precursor. The influence of each of the primary deposition parameters, substrate temperature, total flow rate, and precursor concentration on growth rate, conversion efficiency and morphology were investigated. The operating conditions were determined for kinetic, mass transfer, and evaporation process control regimes. Kinetic controlled deposition was found to produce equiaxed morphology while mass transfer controlled deposition produced columnar morphology. A kinetic model of the deposition process was developed and compared to data for deposition of TiO2 from Ti(OC3H7) 4 precursor. The results demonstrate that growth rate and morphology over the range of process operating conditions would make the Pulsed-MOCVD system suitable for application of thermal barrier coatings, electrical insulating layers, corrosion protection coatings, and the electrolyte layers in solid oxide fuel cells.

Krumdieck, Susan Pran

245

Numerical simulation of ultrasonic tomography inspections of highly heterogeneous materials  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

246

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

NASA Technical Reports Server (NTRS)

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

Smith, G. R.

1978-01-01

247

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

Microsoft Academic Search

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

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

2000-01-01

248

Ultrasonic techniques in oil well logging  

SciTech Connect

Oil well logging is used to provide the oil and gas industry with information essential to discovering and extracting hydrocarbons. This paper addresses two ultrasonic measurements that are presently used in oil well logging. The most widely used is an ultrasonic technique that evaluates the integrity of the cement seal after a steel casing has been lowered and cemented in place. This instrument is also capable of monitoring the effects of corrosion both on the inner and outer surfaces of the casing. The measurement is based on a pulsed resonant technique. Less widely used is the Borehole Televiewer, an ultrasonic scanning device based on a pulse-echo technique. It provides an acoustic image of geologic features such as rock layers and fractures.

Havira, R.M.

1988-01-01

249

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

250

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

251

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

252

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

NASA Astrophysics Data System (ADS)

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

Ajay Kumar, M.; Srikanth, N. V.

2014-03-01

253

Transmission studies of explosive vaporization of a transparent liquid film on an opaque solid surface induced by excimer-laser-pulsed irradiation  

NASA Astrophysics Data System (ADS)

The dynamics of the explosion of a liquid film by an ultraviolet excimer pulsed laser is studied experimentally on top of an amorphous silicon (a-Si) film deposited on fused quartz. In particular, the transient temperature as well as the nucleation of the superheated liquid at the interface for laser fluences below and above the spontaneous nucleation threshold are monitored using an optical transmission technique. Results for different pure and mixed liquids are presented for cases of different thicknesses of the a-Si film. Details for the calibration of the transmission signal to obtain the interface temperature are provided through the application of the one-dimensional diffusion model and the characteristic matrix theory using data obtained from previous steady-state experiments. The calibrated results are in reasonable agreement with the known data for superheated liquids in the literature as well as theoretical calculations. In addition, the delay times for spontaneous nucleation of the liquids are estimated to be ?1 ?s, generally comparable with those observed in droplet explosion experiments.

Leung, P. T.; Do, Nhan; Klees, Leander; Leung, W. P.; Tong, Frank; Lam, Lui; Zapka, Werner; Tam, Andrew C.

1992-09-01

254

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

PubMed

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

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

2015-04-01

255

Autonomous data transmission apparatus  

DOEpatents

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

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

1997-01-01

256

Autonomous data transmission apparatus  

DOEpatents

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

Kotlyar, O.M.

1997-03-25

257

Ultrasonic characterization of laser ablation  

SciTech Connect

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

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

1991-01-01

258

Analysis of microcracks in dry polycrystalline NaCl by ultrasonic signal processing  

SciTech Connect

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

Sears, F.M.

1980-07-01

259

Ultrasonic Ranging System With Increased Resolution  

NASA Technical Reports Server (NTRS)

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

Meyer, William E.; Johnson, William G.

1987-01-01

260

Design of embedded endoscopic ultrasonic imaging system  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

261

Ultrasonic angle beam standard reflector. [ultrasonic nondestructive inspection  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

262

Ultrasonic Method for Measuring Internal Temperature Profile in Heated Materials  

NASA Astrophysics Data System (ADS)

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

Ihara, I.; Takahashi, M.

2008-02-01

263

Ultrasonic Monitoring of Internal Temperature Distribution in a Heated Material  

NASA Astrophysics Data System (ADS)

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

Takahashi, Manabu; Ihara, Ikuo

2008-05-01

264

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

265

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

266

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

267

Measurement Interpretation and Uncertainty Resulting from Nonlinear Ultrasonic Wave Propagation  

Microsoft Academic Search

.    Nominally identical ceramic-element ultrasonic transducers, of the type used in the aerospace and metals industries for nondestructive\\u000a evaluation (NDE), often have variability in the peak pressure of the generated ultrasonic pulses. The generated pressures\\u000a are also high enough for nonlinear propagation to be present in the water medium, often used as coupling in these types of\\u000a inspections. In

J. A. Slotwinski

1999-01-01

268

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

269

Long-term monitoring of mouse ultrasonic vocalizations.  

PubMed

The temporal pattern of ultrasonic vocalizations by mice in an undisturbed 'home' environment can now be assessed using a system based on amplitude discrimination. Within a chosen frequency band, vocalizations of sufficient intensity are detected by an amplitude discriminator. The output from a pulse generator is sent to a microcomputer which records the time of the incoming event. The system has been validated for monitoring ultrasonic vocalizations in the mouse. PMID:3249761

Warburton, V L; Stoughton, R; Demaine, C; Sales, G D; Milligan, S R

1988-01-01

270

Ultrasonic measurement apparatus and method  

SciTech Connect

Borehole measurement apparatus is described comprising a tool adapted for placement within a borehole through earth formations, said tool having a cylindrical body defining an annulus between said borehole wall and said body, said annulus having drilling fluid disposed therein, an ultrasonic transceiver means disposed in said cylindrical body having a sensor element for periodically emitting an ultrasonic transmitter pulse in said drilling fluid toward said borehole wall and for generating echo signals when said pulse is reflected from a surface back to said transceiver means, a delay-line disposed between said sensor element and said drilling fluid of said annulus, whereby a delay-line echo is produced at an interface of said delay-line and said annulus fluid, logic means responsive to said echo signals of said transceiver means for identifying the presence of a delay-line echo signal and storing an approximate maximum amplitude of such delay-line echo signal periodically as a function of time so as to produce a plurality of approximate maximum amplitudes of said delay-line echo signals stored as a function of time, and logic means responsive to said approximate maximum amplitudes of said delay-line echoes stored as a function of time for monitoring a predetermined indicator of said amplitudes and generating a gas-influx alarm signal if said amplitude indicator is greater than a predetermined indicator.

Orban, J.; Mayes, J.C.

1993-05-25

271

Ultrasonic Nondestructive Characterization of Adhesive Bonds  

NASA Technical Reports Server (NTRS)

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

Qu, Jianmin

1999-01-01

272

Studies on Lamb Waves in Long Aluminium Plates Generated Using Laser Based Ultrasonics  

NASA Astrophysics Data System (ADS)

This paper deals with the characterization and analysis of ultrasonic Lamb waves generated in a long aluminium plates using Laser Based Ultrasonic Technique. Nd-YAG pulsed laser is used for ultrasonic generation while He-Ne laser is used for heterodyne detection. The Lamb wave signals are analyzed using Fourier and wavelet transforms. The Lamb wave signals recorded at three diferent source detector distances are analysed and the resuls are presented.

Raghuram, V.; Shukla, R.; Pramila, T.

2010-05-01

273

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

274

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

275

Ultrasonic Doppler velocimetry in liquid gallium  

Microsoft Academic Search

For the first time, flow velocity is measured in a vortex of liquid gallium, using the pulsed Doppler shift ultrasonic method.\\u000a At the top of a copper cylinder filled with liquid gallium, we spin a disk and create a turbulent vortex with a dominant nearly\\u000a axisymmetric velocity field with little variation in the axial direction. The velocity profiles are shown

Daniel Brito; Henri-Claude Nataf; Philippe Cardin; Julien Aubert; Jean-Paul Masson

2001-01-01

276

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

NASA Technical Reports Server (NTRS)

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

Peterson, R. G.

1969-01-01

277

New matching pursuit-based algorithm for SNR improvement in ultrasonic NDT  

Microsoft Academic Search

In this paper a fast and efficient matching pursuit-based algorithm is proposed for SNR improvement in ultrasonic NDT of highly scattering materials. The proposed algorithm utilizes time-shifted Morlet functions as dictionary elements because they are well matched with the ultrasonic pulse echoes obtained from the transducer used in the experiments. The proposed algorithm is fast enough to be used in

N. Ruiz-Reyes; P. Vera-Candeas; J. Curpián-Alonso; R. Mata-Campos; J. C. Cuevas-Martínez

2005-01-01

278

Two-and three-dimensional simulations of ultrasonic propagation through human breast tissue  

E-print Network

Two- and three-dimensional simulations of ultrasonic propagation through human breast tissue T 16802 Abstract: Simulations of spherical-wave ultrasonic pulse propagation through human breast tissue are presented. Breast tissue models were cre- ated by processing of volumetric photographic data from

Mast, T. Douglas

279

GUI-based toolbox in matlab for deconvolution of ultrasonic nondestructive testing signals for defect identification  

Microsoft Academic Search

The use of ultrasonic pulse-echo reflection techniques are popular industrial methods for defect detection in metals. The ultrasonic wave, generated by a piezoelectric transducer coupled to the test specimen, propagates through the material and part of its energy is reflected when it encounters a non-homogeneity or discontinuity in its path, while the remainder is reflected by the back surface of

A. Yamani; M. Bettayeb; U. Qidwai; C. H. Chen

2000-01-01

280

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.

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

2010-07-01

281

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

282

Ultrasonic Measurements and Technologies  

Microsoft Academic Search

This book presents a very useful insight into ultrasonic technology and is based on years of practical experience at the Slovak Technical University of Bratislava. Much of the technology presented has been developed as part of a long-term programme in machine control. In the main, the technology involves the application to air-borne ultrasonics. The book is therefore particularly useful for

R C Preston

1997-01-01

283

Ultrasonic corona sensor study  

NASA Technical Reports Server (NTRS)

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

Harrold, R. T.

1976-01-01

284

Ultrasonic drilling apparatus  

Microsoft Academic Search

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.

E. L. Duran; R. L. Lundin

1989-01-01

285

Ultrasonic drilling apparatus  

Microsoft Academic Search

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.

E. L. Duran; R. L. Lundin

1988-01-01

286

Ultrasonic measurement apparatus  

SciTech Connect

This patent describes borehole measurement apparatus. It comprises a tool adapted for connection in a drill string in the borehole through earth formations, first and second ultra-sonic transmitter means disposed diametrically opposed from each other in the cylindrical body, first and second ultra-sonic transducer means disposed in the cylindrical body, and logic means, processing means, and memory means.

Orban, J.; Mayes, J.C.

1992-07-14

287

On the measurement of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials.  

PubMed

This paper deals with the measurement of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials, such as cementitious materials. To improve the measurement of this parameter on this kind of materials, a linear swept-frequency signal is used to drive an emitter transducer to conduct a through-transmission inspection in immersion. To filter out undesirable frequency content, time-frequency filtering and detection process are performed. The use of this method has been compared with two excitation techniques, the broadband and the narrowband pulses. The results obtained using the swept-frequency excitation together with the time-frequency filtering, allows the determination of the attenuation curves with high accuracy over a wide frequency range without the need for complicated equipment, and improves the effective bandwidth by using a unique pair of transducers. PMID:20537363

Molero, M; Segura, I; Aparicio, S; Hernández, M G; Izquierdo, M A G

2010-08-01

288

Investigation of inductively coupled ultrasonic transducer system for NDE.  

PubMed

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

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

2013-06-01

289

Transmission Modulator/demodulator --  

E-print Network

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

Chen, Sheng

290

Ultrasonic evaluation of the physical and mechanical properties of granites.  

PubMed

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

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

2008-09-01

291

Design and Fabrication of the High Directional Ultrasonic Ranging Sensor to Enhance the Spatial Resolution  

Microsoft Academic Search

A new ultrasonic ranging transducer with high directionality is developed to enhance the spatial resolution in the pulse-echo measurement in air. The concept of the parametric transmitting array is applied to the design. A high-performance piezoelectric micro-machined ultrasonic transducer (pMUT) array is designed and fabricated in this study. The indirectly generated pulse has a beam-width of around 5deg and a

Haksue Lee; Daesil Kang; Wonkyu Moon

2007-01-01

292

Three dimensional ultrasonic imaging  

SciTech Connect

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

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

1993-03-01

293

Ultrasonic assessment of tooth structure  

NASA Astrophysics Data System (ADS)

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

Blodgett, David W.

2002-06-01

294

Ultrasonic Imaging Techniques for Breast Cancer Detection  

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

295

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

296

Ultrasonic displacement system  

NASA Technical Reports Server (NTRS)

An acoustic instrument system is described as a feasible tool for remote measurement of structural velocities. The system involves measurement of the Doppler shift of ultrasonic sound as it is reflected from an oscillating plate. Measurements were performed in air with an ultrasonic frequency source of 42.5 kilohertz. The surface under investigation was a plexiglass plate oscillating sinusoidally at 10, 13, and 15 Hz. Data are presented to show that, in such a system, the measurement of the Doppler shift is dependent upon the acoustic pathlength between the sensing device and the oscillating surface, with the distance between maximum shifts being half the wavelength of the ultrasonic source.

Faulcon, N. D.

1975-01-01

297

Ultrasonic drilling apparatus  

SciTech Connect

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

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

1988-06-20

298

Ultrasonic drilling apparatus  

SciTech Connect

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

1989-05-09

299

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

300

30 ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 45, no. 1, january 1998 Channel Defect Detection in Food Packages  

E-print Network

30 ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 45, no. 1, january- generated channels which simulate defects in food pack- ages using pulse-echo ultrasonic imaging techniques (trilaminate). Pulse-echo techniques in the 13­17 MHz cen- ter frequency range were investigated. The samples

Illinois at Urbana-Champaign, University of

301

Effect of ultrasonic treatment on the morphology of casein particles.  

PubMed

In this study, the effect of ultrasonic treatment duration on the morphology of self-assembled casein particles was investigated by atomic force microscopy (AFM), low vacuum scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In the case of AFM images, the particle analysis which was carried out by the SPIP program showed that the self-assembled casein particles after being ultrasonically treated for 2 min got smaller in size compared to the casein particles that have not been exposed to any ultrasonic treatment. Surprisingly, however, increasing the ultrasonic time exposure of the particles resulted in an opposite effect where larger particles or aggregates seemed to be present. We show that by comparing the results obtained by AFM, SEM and TEM, the information extracted from the AFM images and analyzed by SPIP program give more detailed insights into particle sizes and morphology at the molecular level compared to SEM and TEM images, respectively. PMID:24054168

Lin, Lin; Cui, Haiying; He, Ronghai; Liu, Lei; Zhou, Cunshan; Mamdouh, Wael; Ma, Haile

2014-03-01

302

Detonator comprising a nonlinear transmission line  

DOEpatents

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

Elizondo-Decanini, Juan M

2014-12-30

303

A comparison of laser and EMAT techniques for noncontact ultrasonics  

NASA Astrophysics Data System (ADS)

Noncontact ultrasonic experiments in metals have been undertaken by use both of optical techniques, involving pulsed-laser generation and interferometric detection, and of electromagnetic acoustic transducers (EMATs). The waveforms and directivity patterns resulting from each technique are compared, and the advantages of each are discussed. A system based on pulsed-laser generation and EMAT detection is then proposed as a suitable compromise between the two approaches.

Hutchins, D.; Hu, J.; Lundgren, K.

1986-09-01

304

Linear and Nonlinear Ultrasonic Properties of Granular Soils  

SciTech Connect

The ultrasonic pulse transmission method (100-500 kHz) was adapted to measure compressional (P) and shear (S) wave velocities for synthetic soils fabricated from quartz-clay and quartz-peat mixtures. Velocities were determined as samples were loaded by small (up to 0.1 MPa) uniaxial stress to determine how stress at grain contacts affects ave amplitudes, velocities, and frequency content. Samples were fabricated from quartz sand mixed with either a swelling clay or peat (natural cellulose). P velocities in these dry synthetic soil samples were low, ranging from about 230 to 430 m/s for pure sand, about 91 to 420 m/s for sand-peat mixtures, and about 230 to 470 m/s for dry sand-clay mixtures. S velocities were about half of the P velocity in most cases, about 130 to 250 m/s for pure sand, about 75-220 m/s for sand-peat mixtures, and about 88-220 m/s for dry sand-clay mixtures. These experiments demonstrate that P and S velocities are sensitive to the amount and type of admixed second phase at low concentrations. They found that dramatic increases in all velocities occur with small uniaxial loads, indicating strong nonlinearity of the acoustic properties. Composition and grain packing contribute to the mechanical response at grain contacts and the nonlinear response at low stresses.

Bonner, B.; Berge, P.A.; Aracne-Ruddle, C.M.; Bertete-Auguirre, H.; Wildenschild, D.; Trombino, C.N.; Hardy, E.

2000-04-20

305

Investigation of capacitively coupled ultrasonic transducer system for nondestructive evaluation.  

PubMed

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

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

2013-12-01

306

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

PubMed

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

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

2011-04-01

307

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

NASA Astrophysics Data System (ADS)

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

Qiao, Chunjie; Huang, Zhigang; Zhou, Chao

2013-10-01

308

Ultrasonic sensor for liquid-level inspection in bottles  

Microsoft Academic Search

In this paper, the development of a precise and dynamic ultrasonic distance sensor to measure the level of liquid in bottles for an industrial line is described. For this application, optical, capacitive or mechanical means are not suitable. In the first part the limitations of a conventional pulse-echo ranging system are discussed. A strategy to measure the time of flight

E. Vargas; R. Ceres; J. M. Marti´n; L. Caldero´n

1997-01-01

309

Ultrasonic Elastic Properties of Steel under Tensile Stress  

Microsoft Academic Search

Longitudinal and transverse wave velocities, eight kinds of elastic parameters and dilational and shear dampings of chromium-molybdenum steel have been simultaneously measured at room temperature in terms of acoustoelasticity, by an ultrasonic pulse method. Young, shear and bulk moduli and Lamé parameter apparently decrease with increasing tensile stress, suggesting decrement of rigidity. However, decease in Poisson's ratio shows actual enhancement

Mikio Fukuhara; Asao Sampei

2000-01-01

310

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

311

A Novel Application of Ultrasonic Imaging to Study Smoldering Combustion  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

312

Error-eliminating rapid ultrasonic firing  

DOEpatents

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

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

1993-08-24

313

Error-eliminating rapid ultrasonic firing  

DOEpatents

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

Borenstein, J.; Koren, Y.

1993-08-24

314

Integrated ultrasonic and petrographical characterization of carbonate building materials  

NASA Astrophysics Data System (ADS)

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

Ligas, Paola; Fais, Silvana; Cuccuru, Francesco

2014-05-01

315

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

NASA Astrophysics Data System (ADS)

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

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

2000-05-01

316

Applicability of ultrasonic technique for evaluation of elastic plastic fracture toughness of high manganese steel at low temperatures  

Microsoft Academic Search

A study on the evaluation of elastic-plastic fracture toughness, JIC, by ultrasonic technique is described for a newly developed high manganese steel at low temperature. In order to see the\\u000a applicability of the ultrasonic technique based on pulse echo method at low temperature, special attention was paid to detect\\u000a change point of ultrasonic echo due to the onset of stable

Joon-Hyun Lee

1995-01-01

317

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

318

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

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

319

Ultrasonic communication in frogs.  

PubMed

Among vertebrates, only microchiropteran bats, cetaceans and some rodents are known to produce and detect ultrasounds (frequencies greater than 20 kHz) for the purpose of communication and/or echolocation, suggesting that this capacity might be restricted to mammals. Amphibians, reptiles and most birds generally have limited hearing capacity, with the ability to detect and produce sounds below approximately 12 kHz. Here we report evidence of ultrasonic communication in an amphibian, the concave-eared torrent frog (Amolops tormotus) from Huangshan Hot Springs, China. Males of A. tormotus produce diverse bird-like melodic calls with pronounced frequency modulations that often contain spectral energy in the ultrasonic range. To determine whether A. tormotus communicates using ultrasound to avoid masking by the wideband background noise of local fast-flowing streams, or whether the ultrasound is simply a by-product of the sound-production mechanism, we conducted acoustic playback experiments in the frogs' natural habitat. We found that the audible as well as the ultrasonic components of an A. tormotus call can evoke male vocal responses. Electrophysiological recordings from the auditory midbrain confirmed the ultrasonic hearing capacity of these frogs and that of a sympatric species facing similar environmental constraints. This extraordinary upward extension into the ultrasonic range of both the harmonic content of the advertisement calls and the frog's hearing sensitivity is likely to have co-evolved in response to the intense, predominantly low-frequency ambient noise from local streams. Because amphibians are a distinct evolutionary lineage from microchiropterans and cetaceans (which have evolved ultrasonic hearing to minimize congestion in the frequency bands used for sound communication and to increase hunting efficacy in darkness), ultrasonic perception in these animals represents a new example of independent evolution. PMID:16541072

Feng, Albert S; Narins, Peter M; Xu, Chun-He; Lin, Wen-Yu; Yu, Zu-Lin; Qiu, Qiang; Xu, Zhi-Min; Shen, Jun-Xian

2006-03-16

320

Ultrasonic annular array system for detecting tissue motion  

NASA Astrophysics Data System (ADS)

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

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

2002-04-01

321

Cluster-enhanced sparse approximation of overlapping ultrasonic echoes.  

PubMed

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

Mor, Etai; Aladjem, Mayer; Azoulay, Amnon

2015-02-01

322

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

323

Acoustic ringing effects in pulsed nuclear magnetic resonance probes  

Microsoft Academic Search

The troublesome spurious ringing phenomenon found in pulsed nuclear magnetic resonance probes is explained in terms of the electromagnetic generation and detection of ultrasonic waves. A few techniques for eliminating this problem are discussed.

M. L. Buess; G. L. Petersen

1978-01-01

324

Acoustic ringing effects in pulsed nuclear magnetic resonance probes.  

PubMed

The troublesome spurious ringing phenomenon found in pulsed nuclear magnetic resonance probes is explained in terms of the electromagnetic generation and detection of ultrasonic waves. A few techniques for eliminating this problem are discussed. PMID:18699271

Buess, M L; Petersen, G L

1978-08-01

325

Artificial Intelligence Assists Ultrasonic Inspection  

NASA Technical Reports Server (NTRS)

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

Schaefer, Lloyd A.; Willenberg, James D.

1992-01-01

326

Non-Invasive Intracranial Pulse Wave Monitoring  

Microsoft Academic Search

Non-invasive physiological monitors are important subsystems of intensive care infor- matic systems. New innovative information methods and technology are presented for non-invasive human brain volumetric pulse wave physiological monitoring. Experimental study of a new, non-invasive ultrasonic intracranial pulse wave monitoring tech- nology show the reactions of non-invasively recorded intracranial blood volume pulse waves (IB- VPW) on healthy volunteers in different

Arminas Ragauskas; Gediminas Daubaris; Vytautas Petkus; Romanas Chomskis; Renaldas Raisutis; Vytautas Deksnys; Jonas Guzaitis; Gintautas Lengvinas; Vaidas Matijosaitis

2008-01-01

327

Modeling the 2008 Ultrasonic Benchmark Problems  

NASA Astrophysics Data System (ADS)

Two studies were part of the 2008 QNDE ultrasonic benchmark session. The first study considered the effects of the curvature of a fluid-solid interface on the pulse-echo immersion response of a flat-bottom hole. This was a re-examination of a problem considered in the 2007 benchmark but with a well-characterized transducer and a different set of testing conditions. The second study considered the response of a series of side-drilled holes at different depths. Here we will summarize the results obtained at the Center for NDE (CNDE), Iowa State University, for these two benchmark problems.

Schmerr, Lester W.; Huang, Ruiju

2009-03-01

328

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

329

Ultrasonic imaging and velocimetry in two-phase pipe flow  

SciTech Connect

This paper presents the first results of an experimental and theoretical investigation of the feasibility of using ultrasonic measurements in multiphase pipe flow. Extant downhole flow rate measurement technology used in the petroleum industry is not adequate in some multiphase flow regimes, particularly when the well is deviated from vertical. Ultrasonics offers Doppler velocity and imaging capabilities, both of which could be of great value in production logging. Some air-water measurements, both imaging and velocimetry, are presented, along with a discussion of pulsed Doppler theory.

Morriss, S.L.; Hill, A.D. (Univ. of Texas, Austin (United States))

1993-06-01

330

Nondestructive Evaluation of Graphite-Epoxy Composites by the Laser Ultrasonic Method  

Microsoft Academic Search

A laser ultrasonic method for nondestructive evaluation of the structure of composite materials is proposed. Specimens of graphite-epoxy composites with compaction-type defects and air cavities are investigated. The method is based on the laser thermooptical generation of wide-band acoustic pulses - optoacoustic (OA) signals - in the material investigated. The acoustic pulses backscattered by structural ingomogeneities and defects are registered

A. A. Karabutov; I. M. Pelivanov; N. B. Podymova

2000-01-01

331

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

NASA Astrophysics Data System (ADS)

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

Okafor, A. Chukwujekwu; Dutta, Amitabha

2014-02-01

332

Ultrasonic thermoacoustic energy converter.  

PubMed

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

Flitcroft, Myra; Symko, Orest G

2013-03-01

333

Ultrasonic shear wave couplant  

DOEpatents

Ultrasonically testing of an article at high temperatures is accomplished by the use of a compact layer of a dry ceramic powder as a couplant in a method which involves providing an ultrasonic transducer as a probe capable of transmitting shear waves, coupling the probe to the article through a thin compact layer of a dry ceramic powder, propagating a shear wave from the probe through the ceramic powder and into the article to develop echo signals, and analyzing the echo signals to determine at least one physical characteristic of the article.

Kupperman, David S. (Oak Park, IL); Lanham, Ronald N. (Lockport, IL)

1985-01-01

334

Ultrasonic shear wave couplant  

DOEpatents

Ultrasonically testing of an article at high temperatures is accomplished by the use of a compact layer of a dry ceramic powder as a couplant in a method which involves providing an ultrasonic transducer as a probe capable of transmitting shear waves, coupling the probe to the article through a thin compact layer of a dry ceramic powder, propagating a shear wave from the probe through the ceramic powder and into the article to develop echo signals, and analyzing the echo signals to determine at least one physical characteristic of the article.

Kupperman, D.S.; Lanham, R.N.

1984-04-11

335

Behaviour of spectral transmissions of Bragg gratings written in germania-doped fibres: writing and erasing experiments using pulsed or cw uv exposure  

Microsoft Academic Search

Photoinscriptions of Bragg gratings have been carried out within several germanosilicate fibres via uv side writing near 244 nm. The gratings have been written with a pulsed or a continuous-wave (cw) laser. It has been observed that the refractive index changes were strongly non linear as a function of the exposure time whatever the nature of the source may be.

P. Niay; P. Bernage; S. Legoubin; M. Douay; W. X. Xie; J. F. Bayon; T. Georges; M. Monerie; B. Poumellec

1994-01-01

336

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

337

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

NASA Technical Reports Server (NTRS)

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

Roth, Don J. (Inventor)

1997-01-01

338

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

NASA Technical Reports Server (NTRS)

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

Roth, Don J. (Inventor)

1996-01-01

339

Ultrasonic imaging of the human body  

NASA Astrophysics Data System (ADS)

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

Wells, P. N. T.

1999-05-01

340

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

341

Coupling apparatus for ultrasonic medical diagnostic system  

NASA Technical Reports Server (NTRS)

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

Frazer, R. E. (inventor)

1978-01-01

342

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

343

Broadband Ultrasonic Transducers  

NASA Technical Reports Server (NTRS)

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

Heyser, R. C.

1986-01-01

344

Electromagnetic ultrasonic transducers  

Microsoft Academic Search

Direct electromagnetic generation is a relatively recent addition to the list of techniques available for the generation of ultrasonic waves for nondestructive evaluation purposes. The history and physics of the generation technique will be discussed. In addition, transducer designs for the generation of various types of sound waves (longitudinal, shear and surface) will be presented. In particular, surface wave transducer

T. J. Moran

1979-01-01

345

ULTRASONIC RANGE FINDING SENSOR  

Microsoft Academic Search

During the research within the MAURO (Mobile Autonomous Robot) project (1995 - 1998) the research team from the 'Robot Control Systems' Laboratory has designed and realized an ultrasonic range finding sensor intended to be used in mobile robot navigation. The sensor has been successively improved and the design was adopted also by other research teams within the Automation Department being

Gheorghe Laze; Emil Lupu; Silviu Folea

346

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

347

Ultrasonic Drilling and Coring  

NASA Technical Reports Server (NTRS)

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

Bar-Cohen, Yoseph

1998-01-01

348

Ultrasonic cleaning: Fundamental theory and application  

NASA Technical Reports Server (NTRS)

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

Fuchs, F. John

1995-01-01

349

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

350

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

PubMed

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

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

2012-12-01

351

Preliminary studies of a novel air-coupled ultrasonic inspection system for food containers  

Microsoft Academic Search

Air-coupled ultrasound has been used to perform measurements on liquids and starch-based materials, within containers similar to those used in the food industry. The technique uses capacitance transducers with polymer membranes to generate ultrasonic signals in air over a reasonable bandwidth. Ultrasonic pulse-compression (UPC) is then applied to increase the sensitivity of signals transmitted through the containers. It will be

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

2002-01-01

352

A comparison of deconvolution techniques for the ultrasonic nondestructive evaluation of materials  

Microsoft Academic Search

Several major deconvolution techniques commonly used for seismic applications are studied and adapted for ultrasonic NDE (nondestructive evaluation) applications. Comparisons of the relative merits of these techniques are presented based on a complete set of simulations on some real ultrasonic pulse echoes. Methods that rely largely on a reflection seismic model, such as one-at-a-time L1 spike extraction and MVD (minimum

Sam-kit Sin; Chi-hau Chen

1992-01-01

353

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

354

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

NASA Technical Reports Server (NTRS)

An ultrasonic data display system was developed at NASA Lewis Research Center that allows the user to interactively examine digitized waveforms and processed information associated with any specific scan location of an ultrasonic contact scan. This information is displayed on a video display monitor and includes acquired time-domain waveforms, frequency-domain magnitude and phase spectra, and ultrasonic properties (pulse velocity, phase velocity, reflection coefficient, attenuation coefficient, attenuation coefficient error) as a function of frequency for a material. This report describes the system features and illustrates the system's usefulness for nondestructive materials characterization.

Roth, Don J.; Szatmary, Steven A.

1993-01-01

355

Ultrasonic liquid level monitoring system  

SciTech Connect

This patent describes an ultrasonic probe for insertion into a tank for the measurement of the depth of petrochemical liquid stored in the tank, and for the detection of leaks in the tank in excess of a predetermined limit. It comprises: a substantially cylindrical probe body having a top end and a bottom end, and a length in excess of the depth of liquid to be measured, the probe body having a back ranging target at the bottom end of the body, the probe body being made of a high thermal resistance material; means for holding the probe body in a substantially vertical position within the tank, the probe body extending downward vertically through the surface of the liquid, the bottom end of the probe body being held in contact with the base of the tank; transducer means positioned within the probe body at a first distance above the bottom end of the probe body for transmitting bi-directional pulses along the longitudinal axis to the surface of the liquid and to the bottom end of the probe body, the back ranging target being positioned to reflect a portion of the bi-directional pulses back to the transducer, and the transducer being operable to receive echoes from the back ranging target and from the surface of the liquid; and at least two calibration rods within the probe body, between the transducer and the top end of the body, each calibration rod being positioned at a successively greater predetermined distance from the transducer, and each respective calibration rod having a larger reflective surface.

Caldwell, J.W.; Slobodnik, M.W.

1991-01-15

356

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

357

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

358

21 CFR 872.4850 - Ultrasonic scaler.  

Code of Federal Regulations, 2010 CFR

...Ultrasonic scaler. (a) Identification. An ultrasonic scaler is a device intended for use during dental cleaning and periodontal (gum) therapy to remove calculus deposits from teeth by application of an ultrasonic vibrating scaler tip to the...

2010-04-01

359

NOVEL TECHNIQUES IN ULTRASONIC CORRELATION SPECTROSCOPY  

E-print Network

1 NOVEL TECHNIQUES IN ULTRASONIC CORRELATION SPECTROSCOPY: Characterizing the Dynamics of Strongly this need, we have developed two ultrasonic correlation spectroscopies, Dynamic Sound Scattering (DSS) and Diffusing Acoustic Wave Spectroscopy (DAWS)1 , which exploit the dynamic information present in ultrasonic

Page, John

360

Micromachined piezoelectric ultrasonic transducer with ultra-wide frequency bandwidth  

NASA Astrophysics Data System (ADS)

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

Wang, Tao; Kobayashi, Takeshi; Lee, Chengkuo

2015-01-01

361

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

362

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

363

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

364

Preparation and characterization of Nano Ni–TiN coatings deposited by ultrasonic electrodeposition  

Microsoft Academic Search

Nano Ni–TiN coatings were successfully prepared by ultrasonic electrodeposition on the surface of mild steel. The coating microstructure was investigated by scanning electron microscopy, atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The AFM results indicate that moderate ultrasonication led to homogeneous dispersion of TiN particles in the coatings. HRTEM and XRD results demonstrate that

F. F. Xia; C. Liu; F. Wang; M. H. Wu; J. D. Wang; H. L. Fu; J. X. Wang

2010-01-01

365

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

366

Ultrasonic Doppler measurement of renal artery blood flow  

NASA Technical Reports Server (NTRS)

Implantable pulsed Doppler ultrasonic flowmeter development has resulted in designs for application to the aortas of dogs and humans, and to human renal and coronary arteries. A figure of merit was derived for each design, indicating the degree of its precision. An H-array design for transcutaneous observation of blood flow was developed and tested in vitro. Two other simplified designs for the same purpose obviate the need to determine vessel orientation. One of these will be developed in the next time period. Techniques for intraoperative use and for implantation have had mixed success. While satisfactory on large vessels, higher ultrasonic frequencies and alteration of transducer design are required for satisfactory operation of pulsed Doppler flowmeters with small vessels.

1974-01-01

367

Miniature implantable ultrasonic echosonometer  

NASA Technical Reports Server (NTRS)

A miniature echosonometer adapted for implantation in the interior of an animal for imaging the internal structure of a organ, tissue or vessel is presented. The echosonometer includes a receiver/transmitter circuit which is coupled to an ultrasonic transducer. Power is coupled to the echosonometer by electromagnetic induction through the animal's skin. Imaging signals from the echosonometer are electromagnetically transmitted through the animal's skin to an external readout apparatus.

Kojima, G. K. (inventor)

1978-01-01

368

Solutions for technological performances increasing at ultrasonic aided electrodischarge machining  

Microsoft Academic Search

The paper deals with researches concerning phenomenology and solutions for technological parameters improvement at finishing\\u000a through electrodischarge machining (EDM) aided by ultrasonic (US) longitudinal vibrations of electrode-tool (EDM + US). The\\u000a stability of EDM + US finishing process was obtained increasing the working gap through ignition voltage growing and amplitude\\u000a decrease of US oscillations. Pulse energy minimization aimed to reduce

N. I. Marinescu; D. Ghiculescu; G. Jitianu

2009-01-01

369

Noise reduction in ultrasonic NDT using discrete wavelet transform processing  

Microsoft Academic Search

Discrete Wavelet Processing, with decomposition level-dependent threshold selection is used for the enhancement of the signal-to-noise ratio (SNR) of synthetic and experimental ultrasonic pulse-echo registers. An analysis of the SNR improvement is performed from the results obtained by processing synthetic grain noise registers having an incrusted flaw signal. Different threshold selection techniques, including Universal, Minimax and Sure rules, have been

J. C. Lazaro

2002-01-01

370

Elastic moduli of boron carbide/copper composites from -40/sup 0/C to 800/sup 0/C by ultrasonic methods  

SciTech Connect

An ultrasonic through-transmission technique for high attenuating materials was developed to determine the ultrasonic longitudinal and shear velocities in B/sub 4/C/Cu composites to 800/sup 0/C. Ultrasonic velocity data was used to calculate Young's modulus, shear modulus, and Poisson's ratio for the composites from -40/sup 0/C to 800/sup 0/C. 5 figures, 1 table.

Gieske, J.H.

1980-10-01

371

Ultrasonic measurement of elastic moduli of 17-4 pH stainless steel and uranium -2 molybdenum from -40°C to 800°C  

Microsoft Academic Search

Young's Modulus, shear modulus, and Poisson's ratio for 17-4 pH stainless steel and uranium -2 molybdenum are calculated from ultrasonic longitudinal and shear velocities determined from -40°C to 800°C. The ultrasonic velocities were determined at elevated temperatures using a through-transmission buffer rod arrangement. An indium-gallium slurry bond was used as an ultrasonic couplant between Cupernickel 10 alloy buffer rods and

Gieske

1980-01-01

372

IEEETRANSACTIONS ON SONICS AND ULTRASONICS,VOL. SU-30, NO. 4, JULY 1983 231 ln Vivo Measurement of Thickness or of Speed of  

E-print Network

IEEETRANSACTIONS ON SONICS AND ULTRASONICS,VOL. SU-30, NO. 4, JULY 1983 231 ln Vivo Measurement. INTRODUCTION MPROVEMENTS in ultrasonic pulse echo diagnostic equip- ment have made it possible to observe tissue structures which are thinner than the length value of the range resolution. There are, of course

Illinois at Urbana-Champaign, University of

373

JOURNAL DE PHYSIQUE Colloque C6, supplPment au no 11-12, Tome 33, Novembre-Dtcembre 1972, page 166 ULTRASONIC ABSORPTION MEASUREMENTS  

E-print Network

ULTRASONIC ABSORPTION MEASUREMENTS IN SINGLE MOLECULAR CRYSTALS A. E. VICTOR, H. E. ALTMAN Jr. and K. T mesures seront egalement exposb. Abstract. -Ultrasonic absorption measurements have been made by a pulse with longitudinal waves in the frequency range 6-38 MHz, and over a temperature range 170-250 O K . Present theories

Boyer, Edmond

374

Acoustooptic pulse-echo transducer system  

NASA Technical Reports Server (NTRS)

A pulse-echo transducer system which uses an ultrasonic generating element and an optical detection technique is described. The transmitting transducer consists of a concentric ring electrode pattern deposited on a circular, X-cut quartz substrate with a circular hole in the center. The rings are independently pulsed with a sequence high voltage signals phased in such a way that the ultrasonic waves generated by the separate rings superimpose to produce a composite field which is focused at a controllable distance below the surface of the specimen. The amplitude of the field reflected from this focus position is determined by the local reflection coefficient of the medium at the effective focal point. By processing the signals received for a range of ultrasonic transducer array focal lengths, the system can be used to locate and size anomalies within solids and liquids. Applications in both nondestructive evaluation and biomedical scanning are suggested.

Claus, R. O.; Wade, J. C.

1983-01-01

375

Shielding of Piezoelectric Ultrasonic Probes in Hall Effect Imaging  

PubMed Central

This paper addresses significant sources of electromagnetic noise in Hall effect imaging. Hall effect imaging employs large electrical pulses for signal generation and high sensitivity ultrasonic probes for signal reception. Coherent noise arises through various coupling mechanisms between the excitation pulse and the probe. In this paper, the coupling mechanisms are experimentally isolated and theoretically analyzed. Several methods of shielding the probe from electromagnetic interference are devised and tested. These methods are able to reduce the noise to levels below the random thermal noise, thereby improving the signal-to-noise ratio in HEI by two orders of magnitude. PMID:9921620

Wen, Han; Bennett, Eric; Wiesler, David G.

2010-01-01

376

Pulsed Electromagnet Emat for High Temperatures  

NASA Astrophysics Data System (ADS)

We presented recently a design of Electromagnetic Acoustic Transducer (EMAT) that uses a pulsed electromagnet to provide the required magnetic field for operation. This new EMAT exhibited a significant improvement in the generated ultrasonic signal amplitude and signal to noise ratio, for operation on mild steel samples at room temperature, compared to equivalent EMATs that use permanent magnets. Results for using the pulsed electromagnet EMAT to generate and detect shear waves in mild steel at elevated temperatures are presented here.

Hernandez-Valle, F.; Dixon, S.

2010-02-01

377

Numerical analysis of ultrasonic detection by an EMAT  

NASA Astrophysics Data System (ADS)

In this research, the processes of transmission and detection by electromagnetic acoustic transducers (EMATs) were analyzed numerically. Computed elastodynamic fields visualize how ultrasonic waves propagate in the specimen, reflecting with mode conversion on the boundary surface. Effects of the propagated waves on output signals of a receiver EMAT were discussed by using numerical results of electromagnetic fields induced by the vibration of the specimen. Predicted receiver signals agree well with experimental results, which validates our numerical approach.

Sugiura, Toshihiko; Maruyama, Shinichi

2001-04-01

378

Ultrasonic Velocities in Methane Hydrate-Bearing Ottawa Sand F110  

NASA Astrophysics Data System (ADS)

At the ConocoPhillips Technology Center in Bartlesville, an experimental setup was developed that facilitated ultrasonic velocity measurements of hydrate-bearing sediment samples inside a magnetic resonance imager (MRI). P- and S-wave velocities were determined using the pulse-transmission technique. The waveforms were generated with 500 kHz piezoelectric transducers that were embedded in PEEK end caps. This provided improved impedance matching between transducer and sample, as well as shielding of the transducers from the magnetic field of the MRI. The ultrasonic measurements were conducted in conjunction with magnetic resonance imaging (MRI), which proved to be a valuable tool to determine the gas hydrate saturation and distribution within the specimen. The hydrate-bearing samples were formed by injecting methane into partially water-saturated sand packs, whose porosity ranged around 40 percent. Specimen containing initial water saturations of 20 and 80 percent were investigated in this study. The sample was brought into the gas hydrate stability field by either cooling the pressurized sample or pressurizing the cooled sample. The velocity collected during the course of these experiments exhibited a noticeable dependence on both the initial water saturation as well as the order of pressurization and cooling. Comparison of the experimental data calculated using the pore scale models developed by Ecker et al. (1998) and Helgerud et al. (2000) indicated that the samples with high initial water saturation tended to be load-bearing, whereas samples formed from a low initial water saturation exhibited cementing characteristics. At low saturations, for the specimen that were pressurized after cooling, higher velocities were recorded than for samples that were first pressurized and then cooled afterward.

Rydzy, M. B.; Batzle, M. L.; Hester, K.; Howard, J. J.

2010-12-01

379

Ultrasonic imaging of static objects through an aberrating layer using harmonic phase conjugation approach.  

PubMed

The main goal of this study is to develop a new image reconstruction approach for the ultrasonic detection of small objects (comparable to or smaller than the ultrasonic wavelength) behind an aberrating layer. Instead of conventional pulse-echo experimental setup we used through transmission, as the backscattered field after going twice through the layer becomes much weaker than the through-transmitted field. The proposed solution is based on the Harmonic Phase Conjugation (HPC) technique. The developed numerical model allows to calculate the amplitude and phase distributions of the through-transmitted acoustic field interacting with the objects and received by a linear transducer array either directly or after passing through an additional aberrating layer. Then, the digitized acoustic field received by the array is processed, phase-conjugated, and finally, numerically propagated back through the medium in order to reconstruct the image of the target objects. The reconstruction quality of the algorithm was systematically tested on a numerical model, which included a barrier, a medium behind it, and a group of three scatterers, by varying scatterer distances from the source transducer, their mutual arrangement, and the angle of the incident field. Subsequently, a set of laboratory experiments was conducted (at transmit frequency of 2MHz) to verify the accuracy of the developed simulation. The results demonstrate feasibility of imaging multiple scattering objects through a barrier using the HPC method with better than 1mm accuracy. The results of these tests are presented, and the feasibility of implementing this approach for various biomedical and NDT imaging applications is discussed. PMID:25553713

Mirzania, Raheleh; Shapoori, Kiyanoosh; Malyarenko, Eugene; Maev, Roman Gr

2015-04-01

380

A matching pursuit method for approximating overlapping ultrasonic echoes.  

PubMed

Ultrasonic pulse-echo methods have been used extensively in measuring the thickness of layered structures as well as those of thin adhesive interface layers. When acoustically measuring thin layers, the resulting echoes from two successive interfaces overlap in time, limiting the minimum thickness that can be resolved using conventional pulse-echo techniques. In this paper, we propose a method, named support matching pursuit (SMP), for resolving the individual echoes. The method is based on the concept of sparse signal approximation in an overcomplete dictionary composed of Gabor atoms (elementary functions). Although the dictionary enables highly flexible approximations, it is also overcomplete, which implies that the approximation is not unique. We propose a method for approximation in which each ultrasonic echo is principally represented by a single atom and therefore has a physical interpretation. SMP operates similarly to the sparse matching pursuit (MP) method. It iteratively improves the approximation by adding, at each iteration, a single atom to the solution set. However, our atom selection criterion utilizes the time localization nature of ultrasonic echoes, which causes portions of a multi-echo ultrasonic signal to be composed mainly from a single echo. This leads to accurate approximations in which each echo is characterized by a set of physical parameters that represent the composing ultrasonic echoes. In the current research we compare SMP to other sparse approximation methods such as MP and basis pursuit (BP). We perform simulations and experiments on adhesively bonded structures which clearly demonstrate the superior performance of the SMP method over the MP and BP methods. PMID:20875989

Mor, Etai; Azoulay, Amnon; Aladjem, Mayer

2010-09-01

381

Ultrasonic scanning of multilayer ceramic chip capacitors  

NASA Technical Reports Server (NTRS)

Ultrasonic scanning is compared to neutron radiography and scanning laser acoustic microscopy (SLAM). Data show that SLAM and ultrasonic scanning evaluations are in good agreement. There is poor agreement between N-ray and both ultrasonic techniques because N-ray is insensitive to all but the grossest delaminations. Statistical analysis show a good correlation between ultrasonic scanning and destructive physical analysis.

Bradley, F. N.

1981-01-01

382

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

383

Ultrasonic linear measurement system  

NASA Technical Reports Server (NTRS)

An ultrasonic linear measurement system uses the travel time of surface waves along the perimeter of a three-dimensional curvilinear body to determine the perimeter of the curvilinear body. The system can also be used piece-wise to measure distances along plane surfaces. The system can be used to measure perimeters where use of laser light, optical means or steel tape would be extremely difficult, time consuming or impossible. It can also be used to determine discontinuities in surfaces of known perimeter or dimension.

Marshall, Scot H. (Inventor)

1991-01-01

384

Ultrasonic cleaner evaluation  

NASA Astrophysics Data System (ADS)

A method to evaluate the capabilities of ultrasonic cleaners is described. This method utilizes a ceramic plate on which a metallized coating has been deposited. The plate is immersed in a beaker filled with DI water and a few drops of liquid detergent. The plate is then subjected to a two-minute cleaning cycle. Measurement of the amount of metallized coating that is removed is determined with an image enhancement system. Use of this test reveals several factors that influence cleaning capabilities. These include system frequency, use of a wetting agent in the bath, bath temperature, fixture materials and fixture mounting.

Gillespie, T. J.

1980-10-01

385

Ultrasonic aesthetic cranioplasty.  

PubMed

The management of frontal bone injury is an important issue, and inappropriate management of such injuries may give rise to serious complications. Piezosurgery is a technique used to perform safe and effective osteotomies using piezoelectric ultrasonic vibrations. This instrument allows a safe method for osteotomy of the cranial vault in close proximity to extremely injury-sensitive tissue such as the brain. After a wide review of the literature, the authors present this technical report, introduce the use of piezosurgery to perform a safe "slim-osteotomies" for treatment of posttraumatic frontal bone deformities, and suggest the use of this instrument for aesthetic recontouring of the craniofacial skeleton. PMID:24914759

Robiony, Massimo; Casadei, Matteo; Sbuelz, Massimo; Della Pietra, Lorenzo; Politi, Massimo

2014-07-01

386

Analysis of laser ultrasonic measurements of surface waves on elastic spheres  

SciTech Connect

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. 15 refs., 5 figs.

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

1991-01-01

387

Laser-Ultrasonic Characterization of Fiber Reinforced Composites: Effect of the Generation Laser Transverse Modes  

NASA Astrophysics Data System (ADS)

Laser-ultrasonics has been used with success for the microstructure evaluation of metals by measuring ultrasonic attenuation and velocity. Extension of this technique to fiber reinforced polymer composites could provide useful information such as fiber contents and porosity. Ultrasonic generation in composite materials is usually performed by using a pulsed TEA-CO2 laser operated on several transverse modes. The intensity profile of this laser could change from shot-to-shot, thus affecting the ultrasonic generation pattern and the accuracy of attenuation measurement. Two solutions are possible to overcome this problem. The first reported approach consists in numerically correcting for the diffraction effect by using a Monte Carlo integration after simultaneous acquisition of the ultrasonic signal and the laser mode pattern. The second reported approach consists in modifying the laser resonator to get a single transverse mode while maintaining high energy per pulse, and to make the diffraction correction much simpler. Both approaches have been tested on a bare carbon epoxy plate with laser generation in the thermoelastic regime. The results obtained from using either approaches show a significant improvement and are compared to those obtained by conventional ultrasonics.

Campagne, B.; Lévesque, D.; Bescond, C.; Néron, C.; Blouin, A.; Monchalin, J.-P.

2004-02-01

388

Acousto-optical tunable transmissive grating beam splitter  

NASA Astrophysics Data System (ADS)

We present a tunable transmissive grating beam splitter for multiple laser line separation based on acousto-optic interaction in tellurium dioxide. Acousto-optic devices are well known for light modulation, frequency shifting, filtration or deflection. For a deflector, the incident light beam is monochromatic and the angular deviation is proportional to the ultrasonic frequency excursion. For a tunable filter, the selected wavelength is determined by the ultrasonic frequency. Several wavelengths may be simultaneously diffracted using several associated ultrasonic frequencies and all the diffracted beams have the same angular deviation. Unlike the classical operating modes of acousto-optic devices, we consider the simultaneous diffraction of several optical wavelengths by a single ultrasonic frequency. The device is based on Bragg anisotropic interaction in the specific "Tangent Phase Matching" configuration. The acousto-optic interaction takes place with a single ultrasonic frequency and the diffraction efficiency remains high over a wide optical spectral range. The different diffracted beams are then angularly well separated, due to the slow velocity of the ultrasonic wave propagating in tellurium dioxide. The optical bandwidth is directly related to the operating ultrasonic frequency. Numerical calculations were carried out to determine the main parameters of the device: operating ultrasonic frequency, optical bandwidth, tunability range, crystalline cut and transducer length. A practical device has been designed for visible spectrum. Experimental results will be presented as for example a spectral bandwidth from 450 nm to 550 nm with a RF carrier frequency f = 125 MHz.

Dieulangard, Anthony; Kastelik, Jean-Claude; Dupont, Samuel; Gazalet, Joseph

2014-03-01

389

Photorefractive Interferometers for Ultrasonic Measurements on Paper  

SciTech Connect

Photorefractive interferometers have been employed for the detection of ultrasound in metals and composites since 1991 [1–4]. Instances of laser-generated ultrasound and laser-based detection in paper were reported in 1996 [5]. More recently, bismuth silicon oxide (BSO) photorefractive interferometers were adapted to detect ultrasound in paper [6]. In this article we discuss BSO and GaAs photorefractive detection of ultrasound on different paper grades and present the resulting waveforms. Compared to contact piezoelectric transducer methods, laser interferometry offers signifcant advantages. One of these is that it is a noncontact technique. This is especially important for on-line application to lightweight papers which could be marked or damaged by contact transducers. Broadband ultrasonic laser generation matched with the broadband sensitivity of laser interferometers is another beneft. This is important for obtaining narrow pulses in nondispersive time-of-fight determinations and for measuring the phase velocity of dispersive modes over a wide frequency band. Also, laser ultrasonic techniques provide a measure of bending stiffness through the analysis of low frequency A0 waves.

Lafond, E. F.; Brodeur, P. H.; Gerhardstein, J. P.; Habeger, C. C.; Telschow, Kenneth Louis

2002-12-01

390

Determining the elastic properties of epoxy / semiconductive glass composites by ultrasonic method  

NASA Astrophysics Data System (ADS)

The purpose of this study is to investigate the effects of the type and amount of semiconductive fillers on the elastic properties of epoxy (ER) / semiconductive glass (SG) composites by ultrasonic velocity measurments. Different semiconducting glasses (SG) binary systems such as As2S3-TlS and As2Se3-TlS were synthesized. ER/SG composites were formed 15 wt. % of fillers and characterized by ultrasonic velocity measurments. The ultrasonic wave velocities of composites were measured with the pulse-echo method at room temperature by a flaw detector. The values of the acoustic impedance, Poisson's ratio, and elasticity constants of the samples were calculated by the measured values of both longitudinal and shear ultrasonic wave velocities. According to the results, The highest elastic properties values were found in the ER/SG-3 composite using 50% As2Se3-50% TlS.

Oral, Imran; Soydal, Ulku

2014-05-01

391

Petawatt pulsed-power accelerator  

DOEpatents

A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

Stygar, William A. (Albuquerque, NM); Cuneo, Michael E. (Albuquerque, NM); Headley, Daniel I. (Albuquerque, NM); Ives, Harry C. (Albuquerque, NM); Ives, legal representative; Berry Cottrell (Albuquerque, NM); Leeper, Ramon J. (Albuquerque, NM); Mazarakis, Michael G. (Albuquerque, NM); Olson, Craig L. (Albuquerque, NM); Porter, John L. (Sandia Park, NM); Wagoner; Tim C. (Albuquerque, NM)

2010-03-16

392

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). PMID:21711710

2011-01-01

393

Laser ultrasonics evaluation and testing of coated HTR nuclear fuel  

NASA Astrophysics Data System (ADS)

Laser ultrasonics was applied to the manufacturing control of the quality and integrity (no failure) of coated spherical particles designed for High Temperature Reactors (HTR). The coating of the nuclear fuel kernel is designed to prevent from the diffusion of fission products outside the particle during reactor operation. The quality assessment of the coating layers is of major importance. Using laser ultrasonics, we determined the vibration eigenmodes of dummy HTR particles. The vibration spectrum of a HTR particle provides a non-destructive method of evaluating some important mechanical parameters of the coating. Moreover, without damaging the particle, the laser ultrasonics technique allows to test the presence of a crack in the SiC layer, through the observation of the particle vibration spectrum, which is significantly changed, compared to that of a defect-free particle. We applied nanosecond acoustic pulses, i.e., high frequency laser-generated ultrasound, to measure the acoustic velocity of longitudinal waves the SiC layer. This technique provides an alternative method of evaluation of the Young modulus of the SiC layer. We measure the velocity of surface acoustic waves (SAW) on a pyrocarbon layer cross-section and we demonstrated that the anisotropy of the internal pyrocarbon layer can be evaluated by laser ultrasonics.

Amziane, Ahmed; Amari, Mohamed; Mounier, Denis; Breteau, Jean-Marc; Joly, Nicolas; Edely, Mathieu; Larcher, Maxime; Noiré, Paul; Banchet, Julien; Tisseur, David; Gusev, Vitalyi

2011-05-01

394

Measurement of Thin Oil Film Thickness Using Ultrasonic Technique  

NASA Astrophysics Data System (ADS)

An application of ultrasonic technique is attempted for the purpose of measuring thin oil film thickness between two surfaces. The amplitude of the wave reflected from the boundary is vary depending on film thickness, because the ultrasonic wave emitted to the interface between two surfaces does multiple reflection and interference in oil film. Quantitative measurement of oil film thickness then can be possible. For instance, it is possible to measure the submicron film thickness which exists near the point contact formed by convex glass and plate with high frequency probe. And it is confirmed that the oil film thickness estimated from the echo height agrees with the film thickness decided by the curvature of the lens or obtained by the optical interference method, even if it is 100 nm. On the other hand, the thickness of oil film between cylinder and piston ring can be easily measured by setting the small ultrasonic probe on the back of piston ring. For example, the influence of the second ring and oil ring for the behavior of an oil film formed on a top ring is able to evaluate quantitatively. As mentioned above, it is cleared that quantitative evaluation of thin film thickness is possible with investigating the echo height obtained by ultrasonic wave pulse reflection method.

Takeuchi, Akitoshi; Terada, Seiichi; Toda, So

395

Ultrasonic Monitoring of CO2 Uptake and Release from Sand Packs*  

NASA Astrophysics Data System (ADS)

Sequestration of atmospheric CO2 occurs naturally during the formation of calcite cement in sedimentary rock. Acceleration of this process has been proposed as a means of reducing the atmospheric concentration of CO2, which is a major cause of global warming. Calcite may also be precipitated when highly alkaline waste fluid is introduced into the vadose zone from leaking storage tanks. Seismic methods have potential for monitoring these processes. We devised an experiment, guided by geochemical modeling, to determine how the formation of calcite cement in unsaturated sand affects wave propagation. We used the ultrasonic pulse transmission method to measure compressional (P) and shear (S) wave velocities at ultrasonic frequencies (100-500 kHz) through packs of Ottawa sand containing chemically active pore fluids. The samples were saturated with water containing 0.1mol/L of Ca(OH)2 and 0.1mol/L of NaCl and then drained by flowing water saturated, CO2 free N2 gas, to a residual saturation of ~5%, so that the remaining pore fluid resides mainly in pendular spaces between the sand grains. Ambient air saturated with water and containing atmospheric concentration of CO2 was then passed through the sample to effect the precipitation of calcite. Finally, pure water saturated CO2, was flushed through the sample to dissolve most of the precipitated calcite. Over a three day period, measurable changes in Vp and Vs were observed following water saturation, desaturation, calcite precipitation, and calcite dissolution treatments. Changes in the contents of the pore space require waveforms to be recorded before and after each stage of the experiment so both the short and long range effects can be seen. Wave velocities were slow, as is typical for unconsolidated materials, for the dry sand, with values of 365m/s for Vp and 163m/s for Vs. Compressional velocities increased upon desaturation (443m/s), and again following calcite precipitation (460m/s). The compressional velocity measured following the CO2 flush to dissolve the calcite decreased (451m/s). The shear velocities varied similarly to the compressional velocities except that the dry sand shear velocity was faster than the other shear velocities. These preliminary results suggest that ultrasonics could provide a tool to locate the path of certain types of waste fluid in the vadose zone. *This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract number W-7405-ENG-48 and was supported specifically by the Environmental Management Science Program of the Office of Environmental Management and the Office of Energy Research.

Toffelmier, D. A.; Dufrane, W. L.; Bonner, B. P.; Viani, B. E.; Berge, P. A.

2002-12-01

396

Transmission Communication  

E-print Network

ELEC3028 Digital Transmission -- MODEM S Chen Digital Communication System . Purpose: communicate: rate, quality # spectral bandwidth requirement . Major components: CODEC, MODEM and channel modulation input output CODEC MODEM Medium 1 #12; ELEC3028 Digital Transmission -- MODEM S Chen Digital

Chen, Sheng

397

AQUIFER TRANSMISSIVITY  

EPA Science Inventory

Evaluation of groundwater resources requires the knowledge of the capacity of aquifers to store and transmit ground water. This requires estimates of key hydraulic parameters, such as the transmissivity, among others. The transmissivity T (m2/sec) is a hydrauli...

398

Time-Frequency Analysis of Long Range Ultrasonic Signals  

NASA Astrophysics Data System (ADS)

Long range ultrasonic testing (LRUT) is a relatively new development within the non-destructive testing sector. Traditionally, conventional ultrasonic testing (UT) is performed at high frequencies, in the MHz range, and is capable of detecting small flaws within a range of millimetres; whereas long range ultrasonic inspection is carried out at lower frequencies, typically between 20 and 100kHz, and is capable of highlighting structural detail and discontinuities tens of metres from a test position. Conventional ultrasonic testing relies on the transmission of bulk waves, the velocities of which are independent of frequency and can usually be predicted easily if the elastic properties of the material under test are known. The dynamics of guided waves, however, are dependent upon frequency making the analysis of received data from a specimen complex. This paper will serve as an introduction to time-frequency representation and may allow a clearer understanding of the non-stationary raw signals produced by this inspection process. Currently, LRUT data are assessed in the time or distance domain using the amplitude vs. time 'A-Scan', therefore structural features and potential flaws are highlighted on a time-of-flight basis. However, as the data obtained are dynamic in time and frequency (non-stationary), time-frequency distributions could provide a mode identification or de-noising process to deal with the problem of coherent noise.

Thornicroft, Keith; Mares, Cristinel; Mudge, Peter

2012-08-01

399

Comparison of x-ray computed tomography, through-transmission ultrasound, and low-kV x-ray imaging for characterizing green-state ceramics  

SciTech Connect

Green-state MgAl/sub 2/O/sub 4/ compact disk specimens have been studied by x-ray computed tomography (CT), through-transmission pulsed ultrasound, and low-kV x-ray imaging to compare the abilities of these nondestructive evaluation (NDE) methods to detect flaws and density variations. X-ray computed tomographic images were obtained from a 125-kV (peak) imaging system with a 512 x 512 matrix and a pixel size of 100 ..mu..m. A 3- to 10- MHz focused-beam ultrasonic transducer was used, together with special immersion techniques, to obtain topographical maps of acoustic attenuation and phase velocity; a 30 x 30 matrix was used in the ultrasonic scans. A 35-kV x-ray system with high-resolution type RR film was used to obtain conventional radiographs. Large-scale nonuniform density gradients were detected with CT and ultrasonics in supposedly uniform ceramic disks. In addition, inclusions in the green-state samples were detected by all three methods, with each method providing certain advantages. The influence of grain structure and other ceramic powder characteristics will be examined in the future. 5 refs., 9 figs.

Roberts, R.A.; Ellingson, W.A.; Vannier, M.W.

1985-06-01

400

Effect of ultrasonic vibration of tool on electrical discharge machining of cemented tungsten carbide (WC-Co)  

Microsoft Academic Search

This paper deals with the effect of copper tool vibration with ultrasonic (US) frequency on the electrical discharge machining\\u000a (EDM) characteristics of cemented tungsten carbide (WC-Co). It was found that ultrasonic vibration of the tool (USVT) was\\u000a more effective in attaining a high material removal rate (MRR) when working under low discharge currents and low pulse times\\u000a (finishing regimes). In

Amir Abdullah; Mohammad R. Shabgard

2008-01-01

401

Void detection beneath reinforced concrete sections: The practical application of ground-penetrating radar and ultrasonic techniques  

Microsoft Academic Search

Ground-penetrating radar (GPR) and ultrasonicpulse echo’ techniques are well-established methods for the imaging, investigation and analysis of steel reinforced concrete structures and are important civil engineering survey tools. GPR is, arguably, the more widely-used technique as it is suitable for a greater range of problem scenarios (i.e., from rebar mapping to moisture content determination). Ultrasonic techniques are traditionally associated

Nigel J. Cassidy; Rod Eddies; Sam Dods

2011-01-01

402

Ultrasonic Welding of Hybrid Joints  

NASA Astrophysics Data System (ADS)

A central research field of the Institute of Materials Science and Engineering at the University of Kaiserslautern (WKK), Germany, is the realization of innovative hybrid joints by ultrasonic metal welding. This article gives an overview of suitable ultrasonic welding systems as well as of essential machine and material parameters, which influence the quality of the welds. Besides the ultrasonic welding of dissimilar metals such as Al to Cu or Al to steels, the welds between newly developed materials like aluminum foam sandwiches or flat flexible cables also can be realized. Moreover, the joining of glass and ceramic to sheet metals is a point of interest at the WKK. By using the ultrasonic metal welding process, it is possible to realize metal/glass welds with tensile shear strengths of 50 MPa. For metal/ceramic joints, the shear strengths values up to 150 MPa were measured. Finally, selected results about the occurring bonding mechanisms will be discussed.

Wagner, Guntram; Balle, Frank; Eifler, Dietmar

2012-03-01

403

Damage detection and characterization of fiber-reinforced composites using ultrasonics  

NASA Astrophysics Data System (ADS)

Due to the prevalence of fiber-reinforced composites in industrial applications, the need for damage-detection and characterization has increased. Ultrasonic nondestructive testing (NDT) is a powerful and non-invasive method of detecting flaws and defects in composite materials. Air-coupled and immersion UT techniques are used to quantify the effect of matrix microcracking and delamination within the composite laminate. Detection of matrix microcracks in the laminate is of primary concern since microcracking is one of the initial damage modes resulting in local stiffness reduction. The techniques considered include pulse-echo in immersion, angle-beam through-transmission Lamb wave time-of-flight shift and velocity measurements, and angle-beam backscatter measurements from single microcracks within the composite laminate. The time-of-flight measurements are shown to be a reasonable method for quantifying stiffness reduction in the laminate, however special attention must be provided to the Lamb modes considered and their sensitivity to the independent stiffness components. The angle-beam backscatter technique may be used to detect individual microcracks but poses a limitation on the frequency and depth of inspection. Ultimately, the quantification of microcracking will provide an early descriptor of failure in the laminate.

Subramanian, Ajith

404

Change of Ultrasonic Reflectivity with Small Air Gap in Solid-Solid Boundary  

Microsoft Academic Search

Ultrasonic testing is useful for detecting plastic-metal debonding in an IC package. A positive phase echo relative to an input pulse is received from the bond region, whereas a negative phase echo is received from the debonding region because of the difference of acoustic impedance between the plastic and metal in the IC package. The purpose of this study is

K. Date; Y. Udagawa; T. Watanabe; I. Sakashiro

1992-01-01

405

Enhancement of Localized Heating by Ultrasonically Induced Cavitation in High Intensity Focused Ultrasound Treatment  

Microsoft Academic Search

There are reports that ultrasonically induced cavitation bubbles locally enhance tissue heating in high intensity focused ultrasound (HIFU) treatment. In this study, a high-intensity burst (named ``a triggering pulse'') above the cavitation threshold was used to trigger cavitation. Immediately after that, CW ultrasound (named ``heating waves''), at an intensity level and duration typical for conventional HIFU ablation was irradiated. Before

Ryo Takagi; Shin Yoshizawa; Shin-ichiro Umemura

2010-01-01

406

Ultrasonic tips in periradicular surgery  

Microsoft Academic Search

Technological advances have increased the rate of success of dental procedures. In periradicular surgery, the use of ultrasonic tips ensures high-quality root-end cavity preparations, enables the performance of a 90-degree apicoectomy, and removes larger amounts of contaminated material. The authors reviewed in vitro and in vivo studies in the literature and evaluated root-end cavities prepared with burs or ultrasonic tips

Marília Gerhardt de Oliveira; Maria Cristina Rockenbach Binz; Patrícia Wehmeyer Fregapani; Cristina Braga Xavier; Daniel Humberto Pozza

2008-01-01

407

Ultrasonic determination of fish composition  

Microsoft Academic Search

Our objective was to ascertain the relationship between the ultrasonic properties of fish and their composition. Fish analogs with varying protein (15–25 wt%), lipid (0–25 wt%) and moisture (55–80 wt%) contents were prepared by mixing dried cod powder, sunflower oil and distilled water. The temperature dependence of the ultrasonic velocity of fish analogs was measured from 5 to 35 °C.

Reza Ghaedian; John Neil Coupland; Eric Andrew Decker; David Julian McClements

1998-01-01

408

An ultrasonic collision detection system  

Microsoft Academic Search

Robots in manufacturing are increasingly being called on to do complex tasks that require intelligence beyond merely following\\u000a a preprogrammed path. In robotic assembling of mechanisms, welding, machine tending and other tasks, sensing enables robots\\u000a to adapt to their environments.\\u000a \\u000a In this research, an ultrasonic collision detection system for an industrial robot was designed, constructed and tested. Two\\u000a ultrasonic transducers

Larry J. Kutz; Ravindran Rajagopalan; Kofi Nyamekye

1992-01-01

409

Enhancement of asymmetric acoustic transmission  

NASA Astrophysics Data System (ADS)

We report both experimentally and theoretically that enhanced one-way acoustic transmission is realized by coupling a periodical grating with metal plates. This exotic acoustic phenomenon is attributed to the structure-induced resonant excitation of the leaky Lamb modes which arise from the coupling of the diffracted waves with the resonant surface states localized at the interface of the grating and the metal plate. More importantly, we further optimize the structure by introducing two inclined plates, which can convert the reflected energy into the transmitted energy. Our finding has great potential applications in ultrasonic devices.

Sun, Hong-xiang; Zhang, Shu-yi

2013-03-01

410

The acousto-ultrasonic approach  

NASA Technical Reports Server (NTRS)

The nature and underlying rationale of the acousto-ultrasonic approach is reviewed, needed advanced signal analysis and evaluation methods suggested, and application potentials discussed. Acousto-ultrasonics is an NDE technique combining aspects of acoustic emission methodology with ultrasonic simulation of stress waves. This approach uses analysis of simulated stress waves for detecting and mapping variations of mechanical properties. Unlike most NDE, acousto-ultrasonics is less concerned with flaw detection than with the assessment of the collective effects of various flaws and material anomalies. Acousto-ultrasonics has been applied chiefly to laminated and filament-wound fiber reinforced composites. It has been used to assess the significant strength and toughness reducing effects that can be wrought by combinations of essentially minor flaws and diffuse flaw populations. Acousto-ultrasonics assesses integrated defect states and the resultant variations in properties such as tensile, shear, and flexural strengths and fracture resistance. Matrix cure state, porosity, fiber orientation, fiber volume fraction, fiber-matrix bonding, and interlaminar bond quality are underlying factors.

Vary, Alex

1987-01-01

411

Broadband ultrasonic backscattering applied to nondestructive characterization of materials.  

PubMed

A simple method based on the spectrum features of the backscattered signal is proposed to the assessment of scatterers size. The method takes advantage of the band-limited response of the scattering media to an incident broadband pulse. The single to multiple scattering regime transition determines this limited frequency content, which is strongly related to scatterer size. The method is applied to the estimation of graphite particle sizes in cast irons. Good quantitative correlation is obtained between graphite sizes measured by metallography and that obtained using this new ultrasonic method, in spite of the band limitations of the ultrasonic system used in the experiment. By this method, the absolute mean value of the scatterer size can be evaluated, provided that a reasonably good estimate of the concentration of particles is known. PMID:15301002

Kruger, Silvio E; Rebello, João M A; Charlier, Jacques

2004-07-01

412

Non-Contact Ultrasonic Characterization of Defects Using EMATs  

NASA Astrophysics Data System (ADS)

We have developed a non-contact ultrasonic technique for detecting and gauging the depth of surface and subsurface defects in metals. A low-frequency broadband Rayleigh-wave pulse is generated and detected by two electro-magnetic acoustic transducers (EMATs) held at a standoff of up to 5 mm, with laser generation and detection also possible. This technique has applications for online testing such as rail track inspection, where faster speeds than with conventional contact ultrasonic techniques should be possible. We describe experiments gauging the position and depth of cracks by measuring the change in signal amplitude and frequency content with the EMATs on either side of the defect, or by looking for an enhancement of the signal close to the defect.

Edwards, R. S.; Dixon, S.; Jian, X.

2005-04-01

413

Non-Contact Ultrasonic Characterization of Defects Using EMATs  

SciTech Connect

We have developed a non-contact ultrasonic technique for detecting and gauging the depth of surface and subsurface defects in metals. A low-frequency broadband Rayleigh-wave pulse is generated and detected by two electro-magnetic acoustic transducers (EMATs) held at a standoff of up to 5 mm, with laser generation and detection also possible. This technique has applications for online testing such as rail track inspection, where faster speeds than with conventional contact ultrasonic techniques should be possible. We describe experiments gauging the position and depth of cracks by measuring the change in signal amplitude and frequency content with the EMATs on either side of the defect, or by looking for an enhancement of the signal close to the defect.

Edwards, R.S.; Dixon, S.; Jian, X. [University of Warwick, Dept. of Physics, Coventry CV4 7AL (United Kingdom)

2005-04-09

414

Detection of Critical Defects in Rails Using Ultrasonic Surface Waves  

NASA Astrophysics Data System (ADS)

Defects in rails caused by rolling contact fatigue (RCP) are of growing concern to the railway industry. Conventional ultrasonic inspection methods are often not reliable in detecting critical RCF defects. The aim of this work was therefore to develop a reliable screening tool that discriminates between critical and tolerable defects and therefore complements the existing inspection methods. The method presented here employs ultrasonic surface waves which propagate several meters along the railhead. They are excited by a local immersion probe which is operated in pulse-echo mode and scanned along the rail; in practice this would be done using a wheel probe. The excitation frequency was chosen to be around 200 kHz at which there exists a suitable surface wave mode with a sufficient penetration depth. A spatial averaging technique is applied to suppress unwanted guided wave modes and reduce signal complexity. The method has been tested successfully on a number of specimens containing real defects.

Hesse, D.; Cawley, P.

2007-03-01

415

Ultra-short pulse generator  

DOEpatents

An inexpensive pulse generating circuit is disclosed that generates ultra-short, 200 picosecond, and high voltage 100 kW, pulses suitable for wideband radar and other wideband applications. The circuit implements a nonlinear transmission line with series inductors and variable capacitors coupled to ground made from reverse biased diodes to sharpen and increase the amplitude of a high-voltage power MOSFET driver input pulse until it causes non-destructive transit time breakdown in a final avalanche shock wave diode, which increases and sharpens the pulse even more. 5 figures.

McEwan, T.E.

1993-12-28

416

Ultra-short pulse generator  

DOEpatents

An inexpensive pulse generating circuit is disclosed that generates ultra-short, 200 picosecond, and high voltage 100 kW, pulses suitable for wideband radar and other wideband applications. The circuit implements a nonlinear transmission line with series inductors and variable capacitors coupled to ground made from reverse biased diodes to sharpen and increase the amplitude of a high-voltage power MOSFET driver input pulse until it causes non-destructive transit time breakdown in a final avalanche shockwave diode, which increases and sharpens the pulse even more.

McEwan, Thomas E. (Livermore, CA)

1993-01-01

417

Ultrasonic speech translator and communications system  

DOEpatents

A wireless communication system undetectable by radio frequency methods for converting audio signals, including human voice, to electronic signals in the ultrasonic frequency range, transmitting the ultrasonic signal by way of acoustical pressure waves across a carrier medium, including gases, liquids, or solids, and reconverting the ultrasonic acoustical pressure waves back to the original audio signal. The ultrasonic speech translator and communication system (20) includes an ultrasonic transmitting device (100) and an ultrasonic receiving device (200). The ultrasonic transmitting device (100) accepts as input (115) an audio signal such as human voice input from a microphone (114) or tape deck. The ultrasonic transmitting device (100) frequency modulates an ultrasonic carrier signal with the audio signal producing a frequency modulated ultrasonic carrier signal, which is transmitted via acoustical pressure waves across a carrier medium such as gases, liquids or solids. The ultrasonic receiving device (200) converts the frequency modulated ultrasonic acoustical pressure waves to a frequency modulated electronic signal, demodulates the audio signal from the ultrasonic carrier signal, and conditions the demodulated audio signal to reproduce the original audio signal at its output (250).

Akerman, M. Alfred (Knoxville, TN); Ayers, Curtis W. (Clinton, TN); Haynes, Howard D. (Knoxville, TN)

1996-01-01

418

Magnetic and ultrasonic studies on stable cobalt ferrite magnetic nanofluid.  

PubMed

Stable cobalt ferrite nanofluids of various concentrations have been prepared through co-precipitation method. Structural and morphological studies of nanoparticles are made with the help of X-ray diffraction technique and Transmission Electron Microscope respectively and it is found that the particles exhibit face centered cubic structure with an average size of 14 nm. The magnetic properties of the nanofluids have been analyzed at room temperature which revealed ferromagnetic behavior and also the very low value of coupling constant which ensures the negligible interparticle interaction in the absence of magnetic field. Ultrasonic investigations have been made for the nanofluids at different temperatures and magnetic fields. The temperature effects are explained with the help of open and close-packed water structure. The inter particle interactions of surface modified CoFe2O4 particles and the cluster formation at higher concentrations are realized through the variations in ultrasonic parameters. PMID:24188514

Nabeel Rashin, M; Hemalatha, J

2014-03-01

419

Development of a Fieldable Air-Coupled Ultrasonic Inspection System  

NASA Astrophysics Data System (ADS)

This paper describes the development of a non-mechanically encoded, simple, field-worthy air-coupled ultrasonic scanning system that gives quantitative information about the size of damage and underlying structure in composite and aluminum aerospace structures. The system consists of the AIRSCAN® air-coupled ultrasonic testing system, the Flock of Birds® real-time motion tracking equipment, a lightweight composite yoke, and laptop PC with data acquisition and processing software. Through transmission C-scan images are generated manually by moving transducers attached to a yoke across the part's surface. The prototype has produced images for a variety of aircraft composite and metal honeycomb structures containing flaws, damages, and repairs. Field tests on commercial and military aircraft as well as rotor blades have begun. Initial test results are shown.

Peters, J. J.; Barnard, D. J.; Hsu, D. K.

2004-02-01

420

Fundamental experiment for inspection of cooling pipes in operation by using ultrasonic technique  

Microsoft Academic Search

Shear horizontal (SH) wave propagation characteristics were evaluated as a method for identifying defects in stainless steel, with the potential application of developing technology for inspecting defects during operation of nuclear reactors. Defects were positioned between a transmitter and receiver, and the propagation angle of the ultrasonic wave was varied by changing the transmission frequency. Next, the waveform from a

Y. Ohtsuka; M. Higashi; M. Nishikawa

2006-01-01

421

Measurement of alkali-silica reaction progression by ultrasonic waves attenuation  

SciTech Connect

Development of non-destructive methods, developed specifically for assessing the damage induced by alkali-silica reaction (ASR) in concrete structures, is needed in order to carry out a systematic evaluation of the concrete condition. The aim of this study is to monitor the evolution of the ASR-damage in laboratory with concrete samples with ultrasonic pulse velocity and attenuation of ultrasonic waves methods. For this study, results of both methods were compared with expansion and mass variation. One reactive concrete mixture was made with reactive aggregate, and one other mixture, incorporating non-reactive aggregate, was made as a control. Specimens were kept at 38 deg. C in a 1 mol l{sup -1} NaOH solution to accelerate the reaction. Attenuation of transmitted ultrasonic waves appeared to be more appropriate for the evaluation of ASR-damage compared with pulse velocity. The attenuation of accelerated reactive concrete cylinders increased by 90% after 1 year while it increased by 40% for the non-reactive concrete used as a control. Major part of the attenuation increase in the non-reactive concrete is due to liquid absorption. This work suggests that in-situ non-destructive techniques based on ultrasonic wave attenuation, like ultrasonic attenuation tomography, should be developed in order to evaluate the development of ASR in concrete structures. Petrographic examination confirmed that damage to concrete is associated with ASR.

Saint-Pierre, Francois [Centre de Recherche sur les Infrastructures en beton - CRIB, Civil Engineering Department, Universite de Sherbrooke, J1K 2R1 (Canada); Rivard, Patrice [Centre de Recherche sur les Infrastructures en beton - CRIB, Civil Engineering Department, Universite de Sherbrooke, J1K 2R1 (Canada)]. E-mail: Patrice.Rivard@Usherbrooke.ca; Ballivy, Gerard [Centre de Recherche sur les Infrastructures en beton - CRIB, Civil Engineering Department, Universite de Sherbrooke, J1K 2R1 (Canada)

2007-06-15

422

In-Situ Measurement of Internal Temperature Distribution of Sintered Materials Using Ultrasonic Technique  

NASA Astrophysics Data System (ADS)

It is often required to measure internal temperature distribution of a heated material because it is closely related to the materials properties and behavior. In this work, an effective ultrasonic method has been applied to the monitoring of internal temperature distributions of an alumina being heated. The principle of the method is based on the temperature dependence of the velocity of ultrasound propagating through a heated material. In the method, a combined technique of ultrasonic pulse-echo measurements and a finite difference calculation is employed to determine the one-dimensional temperature distribution in a heated material. Shear wave is used for the ultrasonic measurements to improve the accuracy in determining temperature. To verify the feasibility of the method, pulse-echo measurements with a shear wave transducer have been performed for an alumina rod of 14 mm diameter and 25 mm length whose single-end is being heated. The internal temperature distribution and its variation of the alumina are then measured during the heating. The temperature distributions determined by the ultrasonic method almost agree with those obtained by an infrared method. Thus, it is demonstrated that the ultrasonic method has the potential for in-process monitoring of the transient temperature variation of ceramics being processed at high temperatures.

Ihara, I.; Tomomatsu, T.

2011-03-01

423

21 CFR 890.5300 - Ultrasonic diathermy.  

Code of Federal Regulations, 2011 CFR

...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5300 Ultrasonic diathermy. (a) Ultrasonic diathermy for use in...

2011-04-01

424

21 CFR 890.5300 - Ultrasonic diathermy.  

Code of Federal Regulations, 2010 CFR

...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5300 Ultrasonic diathermy. (a) Ultrasonic diathermy for use in...

2010-04-01

425

Novel Real-Time Temperature Diagnosis of Conventional Hot-Embossing Process Using an Ultrasonic Transducer  

PubMed Central

This paper presents an integrated high temperature ultrasonic transducer (HTUT) on a sensor insert and its application for real-time diagnostics of the conventional hot embossing process to fabricate V-cut patterns. The sensor was directly deposited onto the sensor insert of the hot embossing mold by using a sol-gel spray technique. It could operate at temperatures higher than 400 °C and uses an ultrasonic pulse-echo technique. The ultrasonic velocity could indicate the three statuses of the hot embossing process and also evaluate the replication of V-cut patterns on a plastic plate under various processing conditions. The progression of the process, including mold closure, plastic plate softening, cooling and plate detachment inside the mold, was clearly observed using ultrasound. For an ultrasonic velocity range from 2197.4 to 2435.9 m/s, the height of the V-cut pattern decreased from 23.0 to 3.2 ?m linearly, with a ratio of ?0.078 ?m/(m/s). The incompleteness of the replication of the V-cut patterns could be indirectly observed by the ultrasonic signals. This study demonstrates the effectiveness of the ultrasonic sensors and technology for diagnosing the replicating condition of microstructures during the conventional hot embossing process. PMID:25330051

Cheng, Chin-Chi; Yang, Sen-Yeu; Lee, Dasheng

2014-01-01

426

Novel real-time temperature diagnosis of conventional hot-embossing process using an ultrasonic transducer.  

PubMed

This paper presents an integrated high temperature ultrasonic transducer (HTUT) on a sensor insert and its application for real-time diagnostics of the conventional hot embossing process to fabricate V-cut patterns. The sensor was directly deposited onto the sensor insert of the hot embossing mold by using a sol-gel spray technique. It could operate at temperatures higher than 400 °C and uses an ultrasonic pulse-echo technique. The ultrasonic velocity could indicate the three statuses of the hot embossing process and also evaluate the replication of V-cut patterns on a plastic plate under various processing conditions. The progression of the process, including mold closure, plastic plate softening, cooling and plate detachment inside the mold, was clearly observed using ultrasound. For an ultrasonic velocity range from 2197.4 to 2435.9 m/s, the height of the V-cut pattern decreased from 23.0 to 3.2 µm linearly, with a ratio of -0.078 µm/(m/s). The incompleteness of the replication of the V-cut patterns could be indirectly observed by the ultrasonic signals. This study demonstrates the effectiveness of the ultrasonic sensors and technology for diagnosing the replicating condition of microstructures during the conventional hot embossing process. PMID:25330051

Cheng, Chin-Chi; Yang, Sen-Yeu; Lee, Dasheng

2014-01-01

427

Magnetostrictive materials and ultrasonics  

SciTech Connect

In the early 1970s a group of Navy scientists led by A.E. Clark began experimenting with highly magnetostrictive rare earth metals, substances that would lengthen in response to a magnetic field. By 1976 the group had discovered an alloy of iron and terbium that exhibited tremendous levels of magnetostriction. They also discovered that, by adding dysprosium, they could lessen the degree of anisotropy in the magnetization of the alloy. Clark named the new material Terfenol-D after terbium, iron, the Naval Ordinance Lab, and dysprosium. Because Terfenol-D was originally developed for sonar applications, it was regarded as usable at low frequencies only from direct current (dc) to 2 kHz. Furthermore, eddy current activity was believed to be so great that high-frequency operation was deemed impractical. However, Terfenol-D can be used into the ultrasonic frequency range. It exhibits the greatest magnetostrictive effects of any commercially available material and is now positioned for a wide range of high-frequency uses--in which piezoceramic materials were formerly used exclusively. The authors have harnessed the energy efficiency of this alloy and discuss the use of this material in actuators.

Hansen, T.T.

1996-08-01

428

New acousto-ultrasonic techniques applied to aerospace materials  

NASA Technical Reports Server (NTRS)

The use of an NdYAG pulsed laser for generating ultrasonic waves for NDE in resin matrix composites was investigated. A study was conducted of the use of the 1.064 micron wavelength NdYAG pulsed laser with the neat, unreinforced resin as well as graphite fiber/polymer composite specimens. In the case of the neat resins it was found that, at normal incidence, about 25 percent of the laser pulse energy was reflected at the incident surface. An attenuation coefficient for the polyimide resin, PMR-15 was determined to be approximately 5.8 np/cm. It was found in energy balance studies that graphite fiber/polymer specimens attenuate the laser beam more than do neat resins. The increase absorption is in the graphite fibers. The occurrence of laser induced surface damage was also studied. For the polymer neat resin, damage appears as pit formation over a small fraction of the pulse impact area and discoloration over a larger part of the area. A damage threshold was inferred from observed damage as a function of pulse energy. The 600 F cured PMR-15 and PMR-11 exhibit about the same amount of damage for a given laser pulse energy. The damage threshold is between 0.06 and 0.07 J/sq cm.

Kautz, Harold E.

1988-01-01

429

Multilevel Digital Pulse Interval Modulation Scheme for Optical Wireless Communications  

Microsoft Academic Search

In this paper a new pulse time modulation technique known as multilevel-digital pulse interval modulation (MDPIM) is introduced and its properties are presented. Expressions for the pulse train, bandwidth, transmission rate and capacity are given. The performance of MDPIM is compared with other pulse modulation techniques. Also system block diagram and signal simulation are presented

Z. Ghassemlooy; N. M. Aldibbiat

2006-01-01

430

Laser-ultrasonic developments towards industrial applications  

Microsoft Academic Search

Two applications of laser-ultrasonics in the steel industry are described: thickness gauging at elevated temperature of seamless pipes and grain size evaluation by measurement of ultrasonic attenuation. A laser-ultrasonics generating\\/detecting system for use in the steel industry is also discussed

J.-P. Monchalin; J.-D. Aussel; R. Heon; J. F. Bussiere; P. Bouchard; J. Guevremont; C. Padioleau

1988-01-01

431

Ultrasonic transducers for use in air  

Microsoft Academic Search

Fewer applications were found for the use of ultrasonics in air than for ultrasonics in liquids or solids. This was primarily because of the inherent limitations of generating high-intensity sound levels in a gaseous medium, and also because of the extremely high attenuation that accompanies in the propagation of ultrasonic energy through air. Several types of transducers are described for

F. Massa

1965-01-01

432

Interlaboratory Comparison of Ultrasonic Backscatter Coefficient  

E-print Network

Interlaboratory Comparison of Ultrasonic Backscatter Coefficient Measurements From 2 to 9 MHz Keith coefficient is a fundamental ultrasonic property that has been used to character- ize many tissues. Unfortunately, there is currently far less standardization for the ultrasonic backscatter measurement than

Illinois at Urbana-Champaign, University of

433

Temperature dependent ultrasonic characterization of biological media  

E-print Network

Temperature dependent ultrasonic characterization of biological media Goutam Ghoshal,a) Adam C. Other ultrasonic properties, e.g., sound speed and attenuation, of tissues have been estimated versus. Ultrasonic backscatter experiments were performed on tissue-mimicking phantoms and freshly excised rabbit

Illinois at Urbana-Champaign, University of

434

On ultrasonic detection of surface features  

Microsoft Academic Search

Ultrasonic range finding is an inexpensive means of obtaining 3-dimensional information about the surrounding environment. Because of this ultrasonic detection methods have received considerable attention recently, particularly in the robotic community. Unfortunately, ultrasonic range finding suffers from shortcomings that are not found in more expensive techniques such as laser range finding. For example, a laser range finder can determine both

Michael K. Brown

1986-01-01

435

Ultrasonic technology improves drill cuttings disposal  

Microsoft Academic Search

Advancements are being made by employing ultrasonics for onsite cuttings size reduction for slurrification prior to disposal. The size reduction proficiency of this new ultrasonics slurrification system as a medium to reduce the particle size of drill cuttings presents operators with a system that can enhance existing disposal techniques. This article presents results from a recent field trial, where ultrasonic

N. Avern; A. Copercini

1997-01-01

436

Generation of ultrasound by repetitively Q-switching a pulsed Nd:YAG laser  

SciTech Connect

Repetitively Q-switching a Nd:YAG laser during a single flashlamp pulse has been used successfully to generate a train of acoustic pulses with a repetition rate as high as 53 kHz. The spectral content of this multiple-pulse ultrasonic signal is significantly narrower in bandwidth than that of a single pulse. A corresponding reduction in the detection system bandwidth results in a marked improvement in detection sensitivity.

Wagner, J.W.; Deaton J.B. Jr.; Spicer, J.B.

1988-11-15

437

Television Transmission  

Microsoft Academic Search

Experiments in the transmission of television signals over wire lines have been made from time to time as the television art has developed. The present paper discusses experiments made during the summer of 1940 with 441-line, 30-frame interlaced signals transmitted over coaxial cable and other telephone facilities. Some of the general problems of wire transmission have been included. In particular,

M. E. Strieby; C. L. Weis

1941-01-01

438

2008 ULTRASONIC BENCHMARK STUDIES OF INTERFACE CURVATURE--A SUMMARY  

SciTech Connect

In the 2008 QNDE ultrasonic benchmark session researchers from five different institutions around the world examined the influence that the curvature of a cylindrical fluid-solid interface has on the measured NDE immersion pulse-echo response of a flat-bottom hole (FBH) reflector. This was a repeat of a study conducted in the 2007 benchmark to try to determine the sources of differences seen in 2007 between model-based predictions and experiments. Here, we will summarize the results obtained in 2008 and analyze the model-based results and the experiments.

Schmerr, L. W. [Center for NDE, Iowa State University, Ames, IA 50011 (United States); Dept. of Aerospace Eng., Iowa State University, Ames, IA 50011 (United States); Huang, R. [Center for NDE, Iowa State University, Ames, IA 50011 (United States); Raillon, R.; Mahaut, S.; Leymarie, N.; Lonne, S. [CEA/LIST, Saclay point courrier 120 F-91191 Gif sur Yvette Cedex France (France); Song, S.-J.; Kim, H.-J. [School of Mechanical Eng., Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Spies, M. [Fraunhofer Institute for Techno- and Economy Mathematics ITWM, 67663 Kaiserslautern (Germany); Lupien, V. [Acoustic Ideas, 27 Eaton Street, Wakefield, MA 01880 (United States)

2009-03-03

439

Ultrasonic determination of carbon content in uranium metal  

NASA Astrophysics Data System (ADS)

A nondestructive method to determine solute content of carbon in polycrystalline uranium by ultrasonic techniques is currently being developed. The problem is approached by considering first theories developed in the field of physical acoustics applicable to variation in attenuation and elasticity with respect to interstitial and second-phase contents. Attention is given to the physical metallurgy of uranium, specifically phase stability and the effects of carbon concentration on physical properties. Experimental verification of theory is provided using Resonant Ultrasound Spectroscopy (RUS) and pulse-echo time of flight measurements, the former yielding elastic moduli and quality factors and the latter supplying attenuation and velocity information.

Poncelow, J.; Morrell, J.; Olson, D. L.; Mishra, B.

2012-05-01

440

Use Of Video In Microscopic And Ultrasonic Inspection  

NASA Technical Reports Server (NTRS)

Two combinations of video and image-data-processing techniques, tone-pulse encoding and precision acoustic imaging, yield grain- and pore-size distributions. Knowledge of such and of fiber orientation important because these characteristics directly related to tensile strength, hardness, fracture toughness, fracture stress, and resistance to impact. One of these combinations of techniques used in nondestructive evaluation of composite parts; both play important roles in development of lightweight composites for use at high temperatures in advanced engines and aircraft. Video system provides easy access to information on diffraction and refraction like that described in article, "Ultrasonic Inspection With Angular-Power-Spectrum Scanning" (LEW-15386).

Generazio, Edward R.; Roth, Don J.

1994-01-01

441

Ultrasonic velocity measurement using phase-slope cross-correlation methods  

NASA Technical Reports Server (NTRS)

Computer implemented phase-slope and cross-correlation methods are introduced for measuring time delays between pairs of broadband ultrasonic pulse-echo signals for determining velocity in engineering materials. The phase-slope and cross-correlation methods are compared with the overlap method which is currently in wide use. Comparison of digital versions of the three methods shows similar results for most materials having low ultrasonic attenuation. However, the cross-correlation method is preferred for highly attenuating materials. An analytical basis for the cross-correlation method is presented. Examples are given for the three methods investigated to measure velocity in representative materials in the megahertz range.

Hull, D. R.; Kautz, H. E.; Vary, A.

1984-01-01

442

Ultrasonic characterization of the nonlinear elastic properties of unidirectional graphite/epoxy composites  

NASA Technical Reports Server (NTRS)

The theoretical treatment of linear and nonlinear elasticity in a unidirectionally fiber reinforced composite as well as measurements for a unidirectional graphite/epoxy composite (T300/5208) are presented. Linear elastic properties were measured by both ultrasonic and strain gage measurements. The nonlinear properties were determined by measuring changes in ultrasonic natural phase velocity with a pulsed phase locked loop interferometer as a function of stress and temperature. These measurements provide the basis for further investigations into the relationship between nonlinear elastic properties and other important properties such as strength and fiber-matrix interfacial stength in graphite/epoxy composites.

Prosser, William H.

1987-01-01

443

Measuring the acoustic wave velocity and sample thickness using an ultrasonic transducer array  

NASA Astrophysics Data System (ADS)

We suggest a new method for determining the longitudinal and transverse acoustic wave velocities and sample thicknesses, which is based on the measurement and analysis of pulsed echo signals by an array of ultrasonic transducers. Analytical expressions relating the delay of signals detected by the array and the values of parameters to be determined are obtained within the framework of a ray model of the measuring system. Measurements on a reference sample have been performed. The values of ultrasonic wave velocities and sample thickness obtained using the proposed technique agree with the results of measurements using independent methods.

Titov, S. A.; Maev, R. G.; Bogachenkov, A. N.

2009-11-01

444

Flexible ultrasonic pipe inspection apparatus  

DOEpatents

A flexible, modular ultrasonic pipe inspection apparatus, comprising a flexible, hollow shaft that carries a plurality of modules, including at least one rotatable ultrasonic transducer, a motor/gear unit, and a position/signal encoder. The modules are connected by flexible knuckle joints that allow each module of the apparatus to change its relative orientation with respect to a neighboring module, while the shaft protects electrical wiring from kinking or buckling while the apparatus moves around a tight corner. The apparatus is moved through a pipe by any suitable means, including a tether or drawstring attached to the nose or tail, differential hydraulic pressure, or a pipe pig. The rotational speed of the ultrasonic transducer and the forward velocity of the apparatus are coordinated so that the beam sweeps out the entire interior surface of the pipe, enabling the operator to accurately assess the condition of the pipe wall and determine whether or not leak-prone corrosion damage is present.

Jenkins, Charles F. (Aiken, SC); Howard, Boyd D. (Augusta, GA)

1998-01-01

445

Improved ultrasonic standard reference blocks  

NASA Technical Reports Server (NTRS)

A program to improve the quality, reproducibility and reliability of nondestructive testing through the development of improved ASTM-type ultrasonic reference standards is described. Reference blocks of aluminum, steel, and titanium alloys are to be considered. Equipment representing the state-of-the-art in laboratory and field ultrasonic equipment was obtained and evaluated. RF and spectral data on ten sets of ultrasonic reference blocks have been taken as part of a task to quantify the variability in response from nominally identical blocks. Techniques for residual stress, preferred orientation, and micro-structural measurements were refined and are applied to a reference block rejected by the manufacturer during fabrication in order to evaluate the effect of metallurgical condition on block response. New fabrication techniques for reference blocks are discussed and ASTM activities are summarized.

Eitzen, D. G.; Sushinsky, G. F.; Chwirut, D. J.; Bechtoldt, C. J.; Ruff, A. W.

1976-01-01

446

Improved ultrasonic standard reference blocks  

NASA Technical Reports Server (NTRS)

A program to improve the quality, reproducibility and reliability of nondestructive testing through the development of improved ASTM-type ultrasonic reference standards is described. Reference blocks of aluminum, steel, and titanium alloys were considered. Equipment representing the state-of-the-art in laboratory and field ultrasonic equipment was obtained and evaluated. Some RF and spectral data on ten sets of ultrasonic reference blocks were taken as part of a task to quantify the variability in response from nominally identical blocks. Techniques for residual stress, preferred orientation, and microstructural measurements were refined and are applied to a reference block rejected by the manufacturer during fabrication in order to evaluate the effect of metallurgical condition on block response.

Eitzen, D. G.

1975-01-01

447

Ultrasonics finds drill pipe cracks  

SciTech Connect

When a tool is placed into service, it is subjected to stress. If the stress is below the material's endurance limit, the part will theoretically last indefinitely. If the stress levels exceed the endurance limit, however, the material will incur permanent damage that accumulates until the part finally fails. Detecting this damage, known as fatigue, before the tool fails is the purpose of nondestructive testing procedures such as visual examinations and penetrant, magnetic particle, and ultrasonic tests. Ultrasonic testing is gaining popularity as a supplement to the other procedures and as a stand-alone inspection - but its value cannot be fully realized without a clear understanding of the nature of fatigue damage, the limitations of ultrasonics, and the attributes of the other methods of inspection.

Chapman, P.W.

1986-03-01

448

Ultrasonic ash/pyrite liberation  

SciTech Connect

The objective of this project was to develop a coal preparation concept which employed ultrasonics to precondition coal prior to conventional or advanced physical beneficiation processes such that ash and pyrite separation were enhanced with improved combustible recovery. Research activities involved a series of experiments that subjected three different test coals, Illinois No. 6, Pittsburgh No. 8, and Upper Freeport, ground to three different size fractions (28 mesh [times] 0, 200 mesh [times] 0, and 325 mesh [times] 0), to a fixed (20 kHz) frequency ultrasonic signal prior to processing by conventional and microbubble flotation. The samples were also processed by conventional and microbubble flotation without ultrasonic pretreatment to establish baseline conditions. Product ash, sulfur and combustible recovery data were determined for both beneficiation processes.

Yungman, B.A.; Buban, K.S.; Stotts, W.F.

1990-06-01

449

Operating principle of a high resolution ultrasonic ranging system based in a phase processing  

NASA Astrophysics Data System (ADS)

Traditionally, ultrasonic ranging sensors emit pulse trains. The distance traveled by the received signal is calculated from its delay with respect to the emitted signal. There are different strategies to encode the signal in order to determine the delay. In this paper we present a method for encoding amplitude that encodes the amplitude of a signal formed by rectangular pulse trains whose frequency is 40 kHz. The pulse amplitude is encoded in a binary manner according to a pseudorandom sequence. Owing to that the emitted signal is formed by pulse trains whose amplitude is modulated, the impulse response of the designed system generates sinusoidal pulse trains whose amplitude is variable. The proposed strategy uses the phase of signal to position temporally each pulse trains. This positioning has higher precision than the sampling time of the signal.

Chaparro, Laura X.; Contreras, Carlos R.; Meneses, Jaime E.

2013-11-01

450

PLATE WAVE RESONANCE WITH AIR-COUPLED ULTRASONICS  

SciTech Connect

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

Bar, H. N. [National Metallurgical Laboratory, Jamshedpur, India 831007 (India); Dayal, V.; Barnard, D.; Hsu, D. K. [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011 (United States)

2010-02-22

451

Downhole pulse radar  

DOEpatents

A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

Chang, Hsi-Tien

1987-09-28

452

Downhole pulse radar  

DOEpatents

A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole.

Chang, Hsi-Tien (Albuquerque, NM)

1989-01-01

453

Ultrasonic fluid densitometry and densitometer  

DOEpatents

The present invention is an ultrasonic fluid densitometer that uses a material wedge having an acoustic impedance that is near the acoustic impedance of the fluid, specifically less than a factor of 11 greater than the acoustic impedance of the fluid. The invention also includes a wedge having at least two transducers for transmitting and receiving ultrasonic signals internally reflected within the material wedge. Density of a fluid is determined by immersing the wedge into the fluid and measuring reflection of ultrasound at the wedge-fluid interface. 6 figs.

Greenwood, M.S.; Lail, J.C.

1998-01-13

454

Ultrasonics: Fundamentals, Technologies, and Applications  

SciTech Connect

This is a new edition of a bestselling industry reference. Discusses the science, technology, and applications of low and high power ultrasonics, including industrial implementations and medical uses. Reviews the basic equations of acoustics, starting from basic wave equations and their applications. New material on property determination, inspection of metals (NDT) and non-metals, imaging, process monitoring and control. Expanded discussion of transducers, transducer wave-fields, scattering, attenuation and measurement systems and models. New material that discusses high power