These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Ultrasonic flowmetering with reflected pulses  

E-print Network

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

Hoyle, David C.

1984-01-01

2

Ultrasonic thermometry using pulse techniques.  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

3

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

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, Russell B. (Oakland, CA)

1987-01-01

5

Coiled transmission line pulse generators  

DOEpatents

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

McDonald, Kenneth Fox (Columbia, MO)

2010-11-09

6

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

7

Blind deconvolution of ultrasonic traces accounting for pulse variance  

Microsoft Academic Search

The ability of pulse-echo measurements to resolve closely spaced reflectors is limited by the duration of the ultrasonic pulse. Resolution can be improved by deconvolution, but this often fails because frequency selective attenuation introduces unknown changes in the pulse shape. In this paper we propose a maximum a posteriori algorithm for simultaneous estimation of a time varying pulse and high-resolution

Kjetil F. Kaaresen; E. Bolviken

1999-01-01

8

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

9

High current pulse transmission cable  

SciTech Connect

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

Parsons, W.M.

1990-09-28

10

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

11

Power and Information Transmission to Implanted Medical Device Using Ultrasonic  

NASA Astrophysics Data System (ADS)

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 shift keying (ASK), 9.5 Kbps is obtained for the proposed information transmission system.

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

2001-05-01

12

Capacitive micromachined ultrasonic transducer design for high power transmission.  

PubMed

Capacitive micromachined ultrasonic transducers (cMUTs) were developed to meet the demands of the ultrasonic industry. To achieve maximum efficiency, the conventional operation of the cMUT requires a bias voltage close to the collapse voltage. Total acoustic output pressure is limited by the efficiency of the cMUT and the maximum-allowed pulse voltage on the membrane. In this paper, we propose the collapse-snapback operation of the cMUT: the membrane is collapsed onto the substrate in the collapsing cycle, and released in the snapback cycle. The collapse-snapback operation overcomes the above-mentioned limitations of the conventional operation. The collapse-snapback operation utilizes a larger range of membrane deflection profiles (both collapsed and released profiles) and generates higher acoustic output pressures. The static finite element calculations were performed to design cMUTs with specific collapse and snapback voltages by changing the electrode parameters (radius (re), position (de), and thickness (te)). These designs were refined for optimum average displacement per cycle. An electrode radius greater than 60% of the membrane radius significantly improved the displacement per volt. Moderately thick membranes (te approximately 0.2 microm) were preferred, as thicker membranes reduced the displacement per volt. Under proper bias conditions, the collapse-snapback operation, designed for high-power transmission, allowed the application of pulse voltages larger than the difference of collapse and snapback voltages. Dynamic finite element calculations of an infinite cMUT array on the substrate loaded with acoustic fluid medium were performed to determine the dynamic response of the cMUT. Commercially available FEM packages ANSYS and LS-DYNA were used for static and dynamic calculations, respectively. The cMUTs were fabricated for optimal performance in the collapse-snapback operation. The transmit experiments were performed on a 2-D cMUT array using a calibrated hydrophone. Taking into account the attenuation and diffraction losses, the pressure on the cMUT surface was extracted. The cMUT generated 0.47 MPa (6 kPa/V) and 1.04 MPa (11 kPa/V) in the conventional and collapse-snapback operations, respectively. Therefore, collapse-snapback operation of the cMUTs was superior for high-power transmission. PMID:15801320

Bayram, Baris; Oralkan, Omer; Ergun, A Sanli; Haeggström, Edward; Yaralioglu, Goksen G; Khuri-Yakub, Butrus T

2005-02-01

13

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

14

Experimental hardware development for a pulsed ultrasonic data collection facility  

Microsoft Academic Search

The work reported in this thesis used readily available components to implement a data acquisition system for a pulsed ultrasonic data collection facility. Use of hardware with controlling software is necessary to collect waveforms of acoustic potential at a given distance from the transmitting source. Precise movement and positioning of an acoustic receiver in the collection plane is accomplished by

Peter A. Gatchell

1994-01-01

15

Evaluation of a pulsed ultrasonic Doppler flowmeter  

NASA Technical Reports Server (NTRS)

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

Wells, M. K.

1973-01-01

16

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

17

Non-destructive characterization of CMP pads using scanning ultrasonic transmission  

Microsoft Academic Search

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

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

2001-01-01

18

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

19

Automatic recording of ultrasonic travel time using a computer-controlled pulse-echo overlap method  

Microsoft Academic Search

The ultrasonic pulse-echo overlap method is modified to permit automatic recording of the ultrasonic round trip time. A transient recorder is used to capture selected echoes in the echo train. The circuitry used to select the correct trigger pulses for the transient recorder is controlled by the computer. If the transient recorder is triggered with a time interval equal to

M. A. Buyukguclu; T. Alper

1987-01-01

20

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

NASA Astrophysics Data System (ADS)

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

Tackitt, Kirk David

21

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

22

Ultrasonic Transmission Characteristics of In vitro Human Cancellous Bone  

Microsoft Academic Search

An ultrasonic wave transmitted through an in vitro human cancellous bone was experimentally investigated. An osteoporotic cancellous bone specimen was obtained from an in vitro femoral head. A narrow ultrasonic beam was scanned on the specimen surface over an area of 30× 30 mm2 and the transmitted ultrasonic wave was obtained at an interval of 1 mm. Local bone densities

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

2007-01-01

23

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

24

Modelling pulsed-power transmission lines  

SciTech Connect

Transmission lines in modern pulsed-power machines such as PBFA-II operate at ten or more megavolts with multi-megampere currents. They often have series (voltage) or parallel (current) power addition. In these transmission lines the cathodes emit electrons freely. In addition, perturbations such as plasma opening switches cause additional electrons to be launched into the flow. The large magnetic field due to the transmission line current prevents these electrons from crossing the transmission line to the anode directly, but in most situations electron current flows to the anode after traveling a long distance down the transmission line. Usually these losses occur just before the load or at adder points. Reliable modelling of these lines is important both for design purposes and for use in analyzing data. In this paper we will present models that can be used for these purposes. The model will primarily be based upon known symmetries plus measurable parameters. Comparisons to data, particularly data taken on PBFA-II will be made.

Mendel, C.S. Jr.; Seidel, D.B.; Johnson, W.A.; Rosenthal, S.E.

1991-01-01

25

Modelling pulsed-power transmission lines  

SciTech Connect

Transmission lines in modern pulsed-power machines such as PBFA-II operate at ten or more megavolts with multi-megampere currents. They often have series (voltage) or parallel (current) power addition. In these transmission lines the cathodes emit electrons freely. In addition, perturbations such as plasma opening switches cause additional electrons to be launched into the flow. The large magnetic field due to the transmission line current prevents these electrons from crossing the transmission line to the anode directly, but in most situations electron current flows to the anode after traveling a long distance down the transmission line. Usually these losses occur just before the load or at adder points. Reliable modelling of these lines is important both for design purposes and for use in analyzing data. In this paper we will present models that can be used for these purposes. The model will primarily be based upon known symmetries plus measurable parameters. Comparisons to data, particularly data taken on PBFA-II will be made.

Mendel, C.S. Jr.; Seidel, D.B.; Johnson, W.A.; Rosenthal, S.E.

1991-12-31

26

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

PubMed

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

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

2013-02-14

27

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

Microsoft Academic Search

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

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

1983-01-01

28

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

Microsoft Academic Search

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

Kirk David Tackitt

1999-01-01

29

An Active Pulse Transmission Line Simulating Nerve Axon  

Microsoft Academic Search

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

J. Nagumo; S. Arimoto; S. Yoshizawa

1962-01-01

30

Detection of cystic structures using pulsed ultrasonically induced resonant cavitation  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

31

Pulsed power transmission line transformer based on modern cable technology  

Microsoft Academic Search

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

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

2003-01-01

32

PMN-PT high frequency ultrasonic needle transducers for pulsed wave Doppler in the eye  

Microsoft Academic Search

The purpose of this study is to develop miniature intraocular transducers for pulsed wave Doppler. The intended use of this device is for in-vivo high frequency pulsed wave Doppler detection of blood flow in the posterior portion of the eye. High frequency ultrasonic needle transducers were fabricated using lead magnesium niobate-lead titanate (PMN- 33%PT) as the active piezoelectric material. The

Emanuel J. Gottlieb; Bruce Lai; Xiaochen Xu; Jonathan Cannata; Jesse Yen; Qifa Zhou; Pengdi Han; Hossein Ameri; Tanapat Ratanapakorn; Aaron Barnes; Mark Humayun; K. Kirk Shung

2005-01-01

33

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

Microsoft Academic Search

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

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

34

Evaluating residual compressive strength of concrete at elevated temperatures using ultrasonic pulse velocity  

Microsoft Academic Search

In this paper, the ultrasonic pulse velocity (UPV) is used to quantitatively evaluate the residual compressive strength of concrete subjected to elevated temperatures. A series of tests were performed to examine the relationship between the residual UPV and strength of concrete with different mixture proportions at elevated temperatures. Cylindrical specimens were made of concrete with water–cement ratios of 0.58 and

Hsuanchih Yang; Yiching Lin; Chiamen Hsiao; Jian-You Liu

2009-01-01

35

Transmission line pulse transformers—Theory and applications  

Microsoft Academic Search

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

RICHARD E. MATICK

1968-01-01

36

A pulsed phase measurement ultrasonic flowmeter for medical gases  

Microsoft Academic Search

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

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

1984-01-01

37

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

38

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

PubMed

Targeted acoustic contrast agents offer the potential for sensitive ultrasonic detection of pathologic tissues. We have previously reported the development of a ligand-targeted, lipid-encapsulated, liquid perfluorodichlorooctane ultrasonic contrast system with a small nominal particle size (approximately 250-nm diameter). Perfluorocarbon nanoparticles substantially increase reflectivity when bound to targeted surfaces, and we propose that this system can be approximated physically as a simple, thin layer, acoustic transmission line. In this study, we evaluate this model and compare the ultrasonic reflectivity of different perfluorocarbon formulations with widely varying acoustic impedances targeted to either nitrocellulose membranes or plasma thrombi in vitro. Five perfluorocarbons were investigated: perfluorohexane (PFH), perfluorooctane (PFO), perfluorooctyl bromide (PFOB), perfluorodichlorooctane (PFDCO), and perfluorodecalin (PFD). Ultrasonic reflection was measured by acoustic microscopy (17 to 35 MHz). Acoustic reflectivity was increased (P < 0.05) by all targeted perfluorocarbon formulations, and the magnitude of the contrast effect was inversely correlated with the perfluorocarbon acoustic impedance. PFH nanoparticles exhibited the greatest enhancement, and PFD nanoparticles showed the least. The acoustic transmission line model predicted well the relative differences in acoustic reflectivity and frequency dependence among the perfluorocarbon formulations. For future clinical applications, PFO nanoparticles may provide the best combination of acoustic enhancement, in vivo physical stability, and safety. PMID:11833889

Marsh, Jon N; Hall, Christopher S; Scott, Michael J; Fuhrhop, Ralph W; Gaffney, Patrick J; Wickline, Samuel A; Lanza, Gregory M

2002-01-01

39

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

PubMed

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

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

2014-12-15

40

On estimating the center frequency of ultrasonic pulses.  

PubMed

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

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

2004-04-01

41

Transmission of a Kelvin Wave Pulse Through a Strait  

NASA Astrophysics Data System (ADS)

Transmission of Kelvin waves through a strait is of interest wherever two seas are connected by relatively narrow passages (as in the Indonesian Archipelago) and the dynamic interplay between the basins depends in part on the ability of Kelvin waves to penetrate the straits. In the linear limit this has been shown to be a wave interference problem involving multiple reflections within the strait, and a simple analytical expression has been provided for the frequency--dependent energy transmission ratio. The most obvious use of this transmission expression would be as a filter applied to the Fourier spectrum of a given time series. Most Kelvin wave signals are pulse--like, however, and a transform over a long time span may not be the most effective way to represent a series of independent events. We show that a strait can be viewed as a ``first--order instrument'' which has a frequency--dependent response to an oscillatory input, and which adjusts in an exponentially decaying fashion to a sudden change in either the input amplitude or frequency. The characteristic decay scale depends on the ratio of the strait dimensions to the Kelvin wave phase speed. When pulse durations are long compared to this decay time, the energy transmission of each pulse is accurately predicted by applying the simple transmission expression to only the frequencies necessary for defining the pulse within the window of its duration.

Durland, T. S.; Qiu, B.

2002-12-01

42

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

43

Using ultrasonic pulse velocity to evaluate residua l compressive strength of post-fire-curing concrete  

Microsoft Academic Search

In this paper, the ultrasonic pulse velocity (UPV) is used to quantitatively evaluate the residual compressive strength of post-fire-curing c oncrete subjected to elevated temperatures. A series of tests were performed to examine the relat ionship between the residual UPV and strength of post-fire-curing concrete. Cylindrical specimens were made of concrete with various mixture proportions, and heated in an electric

Hsuanchih YANG; Yiching LIN; Chiamen HSIAO; Yu-Feng LIN

44

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

45

Efficient transmit beamforming in pulse-echo ultrasonic imaging  

Microsoft Academic Search

A high performance ultrasound imaging system requires accurate control of the amplitude of the array elements, as well as of the time delays between them, both in the transmit and receive modes. In transmission, conventional array aperture windowing implies a different driving voltage for each element of the array, an expensive solution for systems with a large number of channels.

Gabriella Cincotti; Giovanni Cardone; Paola Gori; Massimo Pappalardo

1999-01-01

46

A Digital Ultrasonic Pulse-Echo Overlap System and Algorithm for Unambiguous Determination of Pulse Transit Time  

SciTech Connect

We report an evolution of an all-digital ultrasonic pulse technique for measurements of elastic constants of solids. An unambiguous analytical procedure is described for determining the correct time delay of echoes without any need for actual echo overlap. We also provide a simple procedure for making corrections for transducer-bond-induced phase shifts. The precision of a measurement made with this system at ambient temperature exceeds one part in 107 without the use of mixers, gates, time delays, and other complications normally associated with such measurements.

Cristian,P.; Rickel, D.; Migliori, A.; Zhang, J.; Zhao, Y.; Leisure, R.; Li, B.

2005-01-01

47

Ultrasonics  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

48

Analysis of Ultrasound Propagation in A Steel Pipe Using Ultrasonic Pulse Doppler Method  

NASA Astrophysics Data System (ADS)

Thermal powers of nuclear reactors are calculated by the enthalpy difference between reactor feed water and main steam. Improvement of the measurement accuracy in the flow rate measurements of reactor feed water enables us to uprate reactor thermal power, called MUR (Measurement Uncertainly Recapture) uprate. The ultrasonic pulse Doppler system is expected to be a suitable method featuring the capability o measuring the flow profile directly in a pipe. For the optimum measurements, ultrasound path from ultrasonic transducer into the fluid through steel pipe wall should be carefully predicted in high temperature water. This paper presents analytical results of ultrasound propagation using FEM simulation code and experimental results of pipe flow rate at high temperature thermal conditions.

Tezuka, Kenichi; Wada, Sanehiro; Mori, Michitsugu; Kikura, Hiroshige; Aritomi, Masanori

49

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

Microsoft Academic Search

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

A. E. Arave; J. Buchenauer

1976-01-01

50

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

PubMed

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

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

2014-07-01

51

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

52

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

53

The ultrasonic weak short-pulse responses of microbubbles based on a two-frequency approximation  

NASA Astrophysics Data System (ADS)

The ultrasonic short-pulse responses of microbubbles are of interest in cavitation, transient responses, and contrast imaging. We extend the two-frequency analytic solutions of Newhouse and Shankar [J. Acoust. Soc. Am. 75, 1473-1477 (1984)] to approximate the short-pulse responses of microbubbles in a low-amplitude field. Based on their results, there is an expected component near dc in the spectrum of bubble echoes excited by a short pulse. Here this component is named the low-frequency response, and its theoretical properties are verified experimentally. Including the fundamental and second-harmonic components, the weak short-pulse responses of microbubbles include three types of response. Our work has determined the constraint conditions under which this approximated solution can be used to analyze these short-pulse responses. This paper also provides the amplitude and spectral properties of these responses. The low-frequency response has a special bandwidth-dependent property and has potential applications in imaging and bubble sizing.

Wu, Chung-Yuo; Tsao, Jenho

2003-11-01

54

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

55

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

PubMed

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

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

2006-12-22

56

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

57

Real-time parallel computation and visualization of ultrasonic pulses in solids.  

PubMed

Parallel processing has changed the way much computational physics is done. Areas such as condensed matter physics, fluid dynamics, and other fields are making use of massively parallel computers to solve immense and important problems in new ways. Simulating wave propagation is another area that has benefited through the use of parallel processing. This is graphically illustrated in this article by various numerical simulations of ultrasonic pulses propagating through solids carried out on a massively parallel computer. These computations are accompanied by visualizations of the resulting wavefield. The calculations and visualizations, together, can be completed in only seconds to several minutes and compare well with experimental data. The computations and parallel processing techniques described should be important in related fields, such as geophysics, acoustics, and mechanics. PMID:17787582

Schechter, R S; Chaskelis, H H; Mignogna, R B; Delsanto, P P

1994-08-26

58

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

59

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

60

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

61

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

62

High-rate transmission scheme for pulse-based ultra-wideband systems over dense multipath  

E-print Network

High-rate transmission scheme for pulse-based ultra-wideband systems over dense multipath indoor-forcing (ZF), and a high-performance ZF-based successive receiver for effective detection in the presence-based ultra-wideband (UWB) systems [1­10] transmits one short- duration, low-duty-cycle pulse every pulse

Liu, Huaping

63

Quantitative Non-Destructive Evaluation Using Laser-Generated Ultrasonic Pulses.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. The work presented here utilises features of laser generated ultrasound for the detection of defects in solids. Ultrasound is generated non-contactively by this method and likewise many of the detection devices used do not require direct coupling to the test pieces, thus acoustic pulses with high frequency components are able to be produced and monitored on a range of samples. Steel samples coated with between 3 and 7mm of plasma-transferred arc depositions are examined for bond quality via measurements of attenuation caused by porosity in the coatings, found to be related to weld current. Surface breaking cracks, (of depth <3mm), in such claddings are quantitatively detected by a method which utilises Rayleigh pulses. A two sided automated scanning system is described which examines samples for subsurface defects. Results from the examinations of a dural test piece, plasma sprayed steel bars and carbon fibre composite samples are presented. Resolution of defects is shown to be within 0.5mm for a 1mm thick section of the composite material. A second scanning technique, requiring access to only one sample face, is presented which employs an interferometer for detection and is thus a truly remote system. Laminar flaws are modelled using flat-bottomed holes, the dimensions of which are measured using the resonance of the bodies. A theoretical investigation using various boundary conditions suggests possible applications for quantitative NDE of structures with well defined natural vibration frequencies. The propagation of acoustic transients in plates is also examined. Possible future work concerning laser/ultrasonic NDE is discussed.

Crosbie, Ross Andrew

64

Direct calibration of a totally implantable pulsed Doppler ultrasonic blood flowmeter.  

PubMed

A totally implantable pulsed Doppler ultrasonic blood flowmeter has recently been developed to provide information on the velocity-flow profile in a vessel as well as its diameter. Volume flow can be indirectly obtained according to the formula: Q = (phi/4)(diam)2-v. In order to determine the accuracy of this estimate, in vivo direct bleedout measurements were performed on the abdominal aorta of six dogs with an overall accuracy in 77 trials of +2.0 +/- 8.7% (mean +/- 1 SD). The best-fit mean linear regression line was found to be: flowmeter output = 1.013-true flow + 5.1 ml/min. The scatter in the flowmeter's accuracy is thought to be due to small variations in the angle of the transducer. The source of the 2% overestimation in the mean accuracy could not be directly attributed to any one condition; the error is sufficiently small that in many cases it can be neglected. PMID:140611

Allen, H V; Anderson, M F; Meindl, J D

1977-05-01

65

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

E-print Network

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

66

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

Microsoft Academic Search

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

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

2002-01-01

67

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

DOEpatents

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

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

2000-01-01

68

Design of Pic-Controlled Pulsed Ultrasonic Transmitter for Measuring Gingiva Thickness  

Microsoft Academic Search

The aim of this study is to design and implement a noninvasive ultrasonic thickness measurement device that determines the gingiva thickness, which is quite an important criterion in dentistry, by using A-mode ultrasonic method. Operating frequency of the device is selected as 8 MHz, since gingival thickness is quite slight. The measurements are performed as 192.5 ?m precision by the implemented system.

Eda Akman Aydin; Inan Guler

2010-01-01

69

Social Transmission of Fear in Rats: The Role of 22kHz Ultrasonic Distress Vocalization  

Microsoft Academic Search

BackgroundSocial alarm calls alert animals to potential danger and thereby promote group survival. Adult laboratory rats in distress emit 22-kHz ultrasonic vocalization (USV) calls, but the question of whether these USV calls directly elicit defensive behavior in conspecifics is unresolved.Methodology\\/Principal FindingsThe present study investigated, in pair-housed male rats, whether and how the conditioned fear-induced 22-kHz USVs emitted by the ‘sender’

Eun Joo Kim; Earnest S. Kim; Ellen Covey; Jeansok J. Kim; Georges Chapouthier

2010-01-01

70

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

71

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 on hand-held mobile phones is 1.6W/kg, as measured over any one gram of tissue. Recently published

Oughstun, Kurt

72

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

73

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

74

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

NASA Astrophysics Data System (ADS)

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

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

1998-05-01

75

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

E-print Network

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

Mast, T. Douglas

76

Study of the Correlation between the Concrete Wall Thickness Measurement Results by Ultrasonic Pulse Echo and the PTF Model for Assymetrical Functions  

Microsoft Academic Search

This paper presents an interpretation of the results of the Pulse-echo methods (Radar Impact-Echo, Ultrasonic Impulse-echo)\\u000a and simulation of wave propagation for testing concrete specimens with metal ducts given in [1-15], in terms of the invariance\\u000a properties of PTF (Practical Test Function) model for asymmetrical pulses presented and developed in [20] and [26].\\u000a \\u000a The interpreted results include various aspects of

Lucian Pusca

2009-01-01

77

Analysis of Ultrasound Propagation in High-Temperature Nuclear Reactor Feedwater to Investigate a Clamp-on Ultrasonic Pulse Doppler Flowmeter  

Microsoft Academic Search

The flow rate of nuclear reactor feedwater is an important factor in the operation of a nuclear power reactor. Venturi nozzles are widely used to measure the flow rate. Other types of flowmeters have been proposed to improve measurement accuracy and permit the flow rate and reactor power to be increased. The ultrasonic pulse Doppler system is expected to be

Kenichi TEZUKA; Michitsugu MORI; Sanehiro WADA; Masanori ARITOMI; Hiroshige KIKURA; Yukihiro SAKAI

2008-01-01

78

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

Microsoft Academic Search

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

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

1998-01-01

79

Pulse sharpening effects of thin film ferroelectric transmission lines  

NASA Astrophysics Data System (ADS)

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

Sleezer, Robert J.

80

Skin-effect considerations on transient response of a transmission line excited by an electromagnetic pulse  

Microsoft Academic Search

The electromagnetic pulse can cause degradation of modern digital and analog devices. Many analytical models have been used extensively to study the susceptibility of equipment related to EMI\\/EMC (electromagnetic interference\\/electromagnetic compatibility) engineering, but the emphasis has been mainly on lossless transmission lines. This work takes into account the transient skin-effect of a transmission line exposed to a time-varying electromagnetic field.

Edward S. M. Mok; George I. Costache

1992-01-01

81

Nonlinear ultrasonic pulsed measurements and applications to metal processing and fatigue  

NASA Astrophysics Data System (ADS)

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

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

2001-04-01

82

Nonlinear ultrasonic pulsed measurements and applications to metal processing and fatigue  

Microsoft Academic Search

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

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

2001-01-01

83

Enhancement of Time-Reversal Subwavelength Wireless Transmission Using Pulse Shaping  

E-print Network

A novel time-reversal subwavelength transmission technique, based on pulse shaping circuits (PSCs), is proposed. Compared to previously reported approaches, this technique removes the need for complex or electrically large electromagnetic structures by generating channel diversity via pulse shaping instead of angular spectrum transformation. Moreover, the pulse shaping circuits (PSCs) are based on Radio Analog Signal Processing (R-ASP), and therefore do not suffer from the well-known issues of digital signal processing in ultrafast regimes. The proposed PSC time-reversal systems is mathematically shown to offer high channel discrimination under appropriate PSC design conditions, and is experimentally demonstrated for the case of two receivers.

Ding, Shuai; Zou, Lianfeng; Wang, Bingzhong; Caloz, Christophe

2014-01-01

84

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

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

85

Temporal profile of optical transmission probe for pulsed-laser heating of amorphous silicon films  

E-print Network

Temporal profile of optical transmission probe for pulsed-laser heating of amorphous silicon films. The temperature-dependence of the material complex refractive index through the thin film thickness is taken, including sur- face hardening, alloying, curing, synthesis of compound and semiconductor films

Xu, Xianfan

86

Responses of transmission-line networks to electrostatic discharge electromagnetic pulses  

NASA Astrophysics Data System (ADS)

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

Zhou, Xing; Wang, Qingguo; Li, Yang

2013-03-01

87

Computational intelligence aspects for defect classification in aeronautic composites by using ultrasonic pulses.  

PubMed

Production of carbon fiber reinforced polymers (i.e., one of the basic material of the modern airplanes) is an elaborate process unfree from faults and problems. Errors during the manufacturing or the plies' overlapping, in fact, can cause particular flaws in the resulting material, so compromising its same integrity. Within this framework, ultrasonic tests could be useful to characterize the presence of defect, depending on its dimensions. On the contrary, the requirement of a perfect state for used polymers is unavoidable in order to assure both transport reliability and passenger safety. Therefore, a real-time approach able to recognize and classify the defect starting from the measured ultrasonic echoes could be very useful in industrial applications. The ill-posedness of the so defined process induce a regularization method. In this paper, an heuristic approach is proposed for this aim. Particularly, the proposed method is based on the use of support vector machines. Obtained results assure good performances of the implemented classifier, with very interesting applications. PMID:18467232

Cacciola, Matteo; Calcagno, Salvatore; Morabito, Francesco Carlo; Versaci, Mario

2008-04-01

88

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

NASA Astrophysics Data System (ADS)

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

Zelinskyy, Yaroslav; May, Volkhard

2014-08-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

90

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

91

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

PubMed Central

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

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

2012-01-01

92

An efficient rate-adaptive transmission technique using shortened pulses for atmospheric optical communications.  

PubMed

In free space optical (FSO) communication, atmospheric turbulence causes fluctuation in both intensity and phase of the received light signal what may seriously impair the link performance. Additionally, turbulent inhomogeneities may produce optical pulse spreading. In this paper, a simple rate adaptive transmission technique based on the use of variable silence periods and on-off keying (OOK) formats with memory is presented. This technique was previously proposed in indoor unguided optical links by the authors with very good performance. Such transmission scheme is now extensively analyzed in terms of burst error rate, and shown in this paper as an excellent alternative compared with the classical scheme based on repetition coding and pulse-position modulation (PPM), presenting a greater robustness to adverse conditions of turbulence. PMID:20721122

Jurado-Navas, Antonio; Garrido-Balsells, José María; Castillo-Vázquez, Miguel; Puerta-Notario, Antonio

2010-08-01

93

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

SciTech Connect

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

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

1989-01-01

94

Pulsed photothermal modeling of composite samples based on transmission-line theory of heat conduction  

Microsoft Academic Search

A transmission-line approach to obtain the thermal solutions for two- and three-layer samples at the front surface is described. These solutions are fitted to pulsed photothermal reflectance data for a Au\\/TAC\\/Si sample. The results indicate that the two- and three-layer models agree with each other and the embedded TAC film can be treated as a thermal resistance. The fitted thermal

George Chen; Ping Hui

1999-01-01

95

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

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

96

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

PubMed

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

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

2014-05-01

97

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

98

Transmission and reflection properties of propagated pulse through defect slab based biexciton coherence  

NASA Astrophysics Data System (ADS)

In this paper, we theoretically investigate transmission and reflection properties of incident light through dielectric medium doped by GaAs/AlGaAs multiple quantum wells with 15 periods of 17.5 nm GaAs wells and 15-nm Al0.3 Ga0.7As barriers, grown by metal organic chemical vapor deposition. The destructive quantum interference is set up by a control pulse that couples to a resonance of biexcitons. We found that many-particle interactions such as biexciton binding energy and biexciton decoherence which are inherent in semiconductors can affect the transmission and reflection properties of incident light on the slab. We have also shown that simultaneous subluminal or superluminal transmission, reflection can be achievable at different frequencies of probe field.

Asadpour, Seyyed Hossein; Soleimani, H. Rahimpour

2014-12-01

99

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

NASA Technical Reports Server (NTRS)

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

Lynnworth, L. C.

1973-01-01

100

New application system for simultaneous laser and ultrasonic transmission in endoscopic surgery (LUST)  

NASA Astrophysics Data System (ADS)

A new combined Laser and Ultrasound Surgical Therapy (LUST) device for an endoscopically suitable coagulation and tissue fragmentation based on the transmission of laser radiation and ultrasound via flexible silica glass fibers was developed at the LMTB. The ultrasound tissue interaction is based on the well-known CUSA-technology, which enables the surgeon to cut various types of tissue with different degrees of effectiveness. This selective cutting performance is a very useful feature, e.g. for a brain tumor extirpation, where it must be guaranteed that vessels and nerves are not affected while ensuring a fast reduction of the tumor mass. Application fields are in oncology, neurosurgery and angioplasty. The laser radiation can be used for tissue coagulation purposes and homeostasis. With a fiber based LUST-system working at a resonance frequency of 30 kHz, using a laser-vibrometer, velocity amplitudes of up to 20 m/s could be detected at the distal end which corresponds to an elongation of more than 100 micrometers . The investigations have shown that the velocity amplitude, next to suction, frequency and cross section of the active fiber tip, has the greatest impact on the fragmentation rate. With a suction setting of 5 W, the following tissue fragmentation rates could be achieved with a 1.3 mm2 fiber cross section and a tip amplitude velocity of 12 m/s: brain tissue 50 mg/s, liver 4,5 mg/s and kidney 4 mg/s. Laser radiation up to 25 watt was sufficient to coagulate soft tissue. This new approach in developing an application system for the therapeutical use of laser radiation and ultrasound via optical waveguides offers new possibilities in minimally invasive surgery, providing a complete new working sphere for the surgeon. The flexible opto-acoustic waveguide (400 - 1700 micrometers ) can be bent making areas accessible which were inaccessible before. The surgeon can use the laser radiation for tissue coagulation or cutting and the ultrasound for tissue fragmentation and tissue reduction without changing the instrumentation.

Desinger, Kai; Helfmann, Juergen; Stein, Thomas; Liebold, K.; Mueller, Gerhard J.

1998-04-01

101

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

102

Nondestructive Ultrasonic Inspection of Braze Bonds in High Current Electrical Contact Assemblies  

Microsoft Academic Search

Ultrasonic techniques are being increasingly used for nondestructive testing and quality control of bonds between the electrical contacts and the support members of the contact assemblies. The state-of-the-art of this valuable tool is analysed and discussed from a control standpoint. Two ultrasonic techniques, namely, the delayed pulse echo and the through-transmission, are described and discussed with respect to their limitations

R. Buckley; P. Popat

1972-01-01

103

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

104

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

105

Pulse record of holographic transmission and reflection diffraction gratings in absorbent photopolymers. 1. Theoretical analysis  

NASA Astrophysics Data System (ADS)

In the present paper, the process of formation of holographic diffraction gratings (HDG) in photopolymer materials in transmission and reflection geometry of record by an optical pulse train with duration comparable with characteristic times of the polymerization and diffusion processes is investigated with allowance for light-induced absorption. A solution of the problem of forming HDG with 2D spatially non-uniform amplitude profiles by light beams is derived in the approximation of zero and first harmonics of the monomer concentration and refractive index. 3D spatial distributions of the HDG amplitude profiles are presented in an analytical form of recursion relations.

Dovolnov, E. A.; Ustyuzhanin, S. V.; Sharangovich, S. N.

2007-01-01

106

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

SciTech Connect

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

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

1987-01-01

107

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

PubMed

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

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

2013-09-01

108

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

109

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

SciTech Connect

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

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

2013-07-01

110

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

SciTech Connect

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

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

2013-06-01

111

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

112

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

113

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

114

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

1992-02-01

115

Losses at magnetic nulls in pulsed-power transmission line systems  

SciTech Connect

Pulsed-power systems operating in the terawatt regime must deal with large electron flows in vacuum transmission lines. In most parts of these transmission lines the electrons are constrained by the self-magnetic field to flow parallel to the conductors. In very low impedance systems, such as those used to drive Z-pinch radiation sources, the currents from multiple transmission lines are added together. This addition necessarily involves magnetic nulls that connect the positive and negative electrodes. The resultant local loss of magnetic insulation results in electron losses at the anode in the vicinity of the nulls. The lost current due to the magnetic null might or might not be appreciable. In some cases the lost current due to the null is not large, but is spatially localized, and may create a gas and plasma release from the anode that can lead to an excessive loss, and possibly to catastrophic damage to the hardware. In this paper we describe an analytic model that uses one geometric parameter (aside from straightforward hardware size measurements) that determines the loss to the anode, and the extent of the loss region when the driving source and load are known. The parameter can be calculated in terms of the magnetic field in the region of the null calculated when no electron flow is present. The model is compared to some experimental data, and to simulations of several different hardware geometries, including some cases with multiple nulls, and unbalanced feeds.

Mendel, C.W. Jr.; Pointon, T.D.; Savage, M.E.; Seidel, D.B.; Magne, I.; Vezinet, R. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1152 (United States); Centre d'Etudes de Gramat, Gramat (France)

2006-04-15

116

Losses at magnetic nulls in pulsed-power transmission line systems.  

SciTech Connect

Pulsed-power systems operating in the terawatt regime must deal with large electron flows in vacuum transmission lines. In most parts of these transmission lines the electrons are constrained by the self-magnetic field to flow parallel to the conductors. In very low impedance systems, such as those used to drive Z-pinch radiation sources, the currents from multiple transmission lines are added together. This addition necessarily involves magnetic nulls that connect the positive and negative electrodes. The resultant local loss of magnetic insulation results in electron losses at the anode in the vicinity of the nulls. The lost current due to the magnetic null might or might not be appreciable. In some cases the lost current due to the null is not large, but is spatially localized, and may create a gas and plasma release from the anode that can lead to an excessive loss, and possibly to catastrophic damage to the hardware. In this paper we describe an analytic model that uses one geometric parameter (aside from straightforward hardware size measurements) that determines the loss to the anode, and the extent of the loss region when the driving source and load are known. The parameter can be calculated in terms of the magnetic field in the region of the null calculated when no electron flow is present. The model is compared to some experimental data, and to simulations of several different hardware geometries, including some cases with multiple nulls, and unbalanced feeds.

Magne, I. (Centre d'Etudes de Gramat, Gramat, France); Savage, Mark Edward; Seidel, David Bruce; Mendel, Clifford Will, Jr.; Pointon, Timothy David; Vezinet, R. (Centre d'Etudes de Gramat, Gramat, France)

2004-08-01

117

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

118

Nanophononic thin-film filters and mirrors studied by picosecond ultrasonics  

Microsoft Academic Search

Optimized acoustic phonon thin-film filters are studied by picosecond ultrasonics. A broadband mirror and a color filter based on aperiodic multilayers were optimized to work in the subterahertz range, and grown by molecular beam epitaxy. Time resolved differential optical reflectivity experiments were performed with pump and probe pulses incident on opposite sides of the substrate. We provide broadband transmission curves

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

2010-01-01

119

Ultrasonic Monitor  

NASA Astrophysics Data System (ADS)

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

1983-01-01

120

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

121

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

NASA Astrophysics Data System (ADS)

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.

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

2011-08-01

122

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

PubMed

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

Burdt, R; Curry, R D

2007-07-01

123

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

124

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

125

Ultrasonic Imaging of Reaction Wood in Standing Trees  

NASA Astrophysics Data System (ADS)

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

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

126

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

NASA Astrophysics Data System (ADS)

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

Mihara, T.; Ishida, H.

2014-06-01

127

Cochlear-Implant High Pulse Rate and Narrow Electrode Configuration Impair Transmission of Temporal Information to the Auditory Cortex  

PubMed Central

In the most commonly used cochlear prosthesis systems, temporal features of sound are signaled by amplitude modulation of constant-rate pulse trains. Several convincing arguments predict that speech reception should be optimized by use of pulse rates ?2,000 pulses per second (pps) and by use of intracochlear electrode configurations that produce restricted current spread (e.g., bipolar rather than monopolar configurations). Neither of those predictions has been borne out in consistent improvements in speech reception. Neurons in the auditory cortex of anesthetized guinea pigs phase lock to the envelope of sine-modulated electric pulse trains presented through a cochlear implant. The present study used that animal model to quantify the effects of carrier pulse rate, electrode configuration, current level, and modulator wave shape on transmission of temporal information from a cochlear implant to the auditory cortex. Modulation sensitivity was computed using a signal-detection analysis of cortical phase-locking vector strengths. Increasing carrier pulse rate in 1-octave steps from 254 to 4,069 pps resulted in systematic decreases in sensitivity. Comparison of sine- versus square-wave modulator waveforms demonstrated that some, but not all, of the loss of modulation sensitivity at high pulse rates was a result of the decreasing size of pulse-to-pulse current steps at the higher rates. Use of a narrow bipolar electrode configuration, compared with the monopolar configuration, produced a marked decrease in modulation sensitivity. Results from this animal model suggest explanations for the failure of high pulse rates and/or bipolar electrode configurations to produce hoped-for improvements in speech reception. PMID:18450583

Middlebrooks, John C.

2008-01-01

128

Cochlear-implant high pulse rate and narrow electrode configuration impair transmission of temporal information to the auditory cortex.  

PubMed

In the most commonly used cochlear prosthesis systems, temporal features of sound are signaled by amplitude modulation of constant-rate pulse trains. Several convincing arguments predict that speech reception should be optimized by use of pulse rates > or approximately 2,000 pulses per second (pps) and by use of intracochlear electrode configurations that produce restricted current spread (e.g., bipolar rather than monopolar configurations). Neither of those predictions has been borne out in consistent improvements in speech reception. Neurons in the auditory cortex of anesthetized guinea pigs phase lock to the envelope of sine-modulated electric pulse trains presented through a cochlear implant. The present study used that animal model to quantify the effects of carrier pulse rate, electrode configuration, current level, and modulator wave shape on transmission of temporal information from a cochlear implant to the auditory cortex. Modulation sensitivity was computed using a signal-detection analysis of cortical phase-locking vector strengths. Increasing carrier pulse rate in 1-octave steps from 254 to 4,069 pps resulted in systematic decreases in sensitivity. Comparison of sine- versus square-wave modulator waveforms demonstrated that some, but not all, of the loss of modulation sensitivity at high pulse rates was a result of the decreasing size of pulse-to-pulse current steps at the higher rates. Use of a narrow bipolar electrode configuration, compared with the monopolar configuration, produced a marked decrease in modulation sensitivity. Results from this animal model suggest explanations for the failure of high pulse rates and/or bipolar electrode configurations to produce hoped-for improvements in speech reception. PMID:18450583

Middlebrooks, John C

2008-07-01

129

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

Microsoft Academic Search

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

Victor V. Kozhushko; Heinz Krenn

2012-01-01

130

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

131

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

132

Ultrasonic testing system based on Bluetooth technology  

Microsoft Academic Search

To achieve the remote control and automation of ultrasonic testing equipment, a Bluetooth-based ultrasonic testing system was developed with single-chip microcomputer as the core and wireless communication technology for data transmission. The system is composed of master and slave units. The slave unit includes the ultrasonic transmitter and receiver circuits, Bluetooth communication module and the microcontroller. It is responsible for

Xiao Chen; Shandong Xiao

2009-01-01

133

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

134

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

PubMed Central

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

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

2010-01-01

135

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

136

Determination of apple firmness by nondestructive ultrasonic measurement  

Microsoft Academic Search

One of the most important quality indicators for fruit is firmness, which is highly correlated with maturity and storage time. This study was conducted to evaluate the potential use of ultrasonic parameters for the determination of apple firmness. The ultrasonic transmission system consisted of an ultrasonic pulser, two ultrasonic transmitting and receiving transducers specially fabricated for fruit, a digital oscilloscope

Ki-Bok Kim; Sangdae Lee; Man-Soo Kim; Byoung-Kwan Cho

2009-01-01

137

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

PubMed

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

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

2010-04-01

138

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

139

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

PubMed

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

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

2013-01-01

140

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

141

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

142

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

PubMed

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

Homma, Akira

2011-07-01

143

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

Microsoft Academic Search

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

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

1998-01-01

144

Suppression of intrachannel four-wave-mixing-induced ghost pulses in high-speed transmissions by phase inversion between adjacent marker blocks  

Microsoft Academic Search

We propose a method for suppressing the intensity of the worst ghost pulse (a single ghost pulse between two long marker blocks) resulting from intrachannel four-wave mixing (FWM) in strongly dispersion-managed on-off keying optical transmissions by inverting the optical phases of the marker blocks surrounding the ghost pulse. We show both analytically and numerically that the method provides substantial suppression

Xiang Liu; Xing Wei; Alan H. Gnauck; Chris Xu; Lisa K. Wickham

2002-01-01

145

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

PubMed

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

Shapiro, Jeffrey H

2011-09-01

146

Model-based ultrasonic tomography  

Microsoft Academic Search

A standard tank for routine ultrasonic non-destructive testing has been used for collecting tomographic data. Side-wall reflections of the tank prevent the use of continuous parallel waves characteristic of most ultrasonic tomography systems. Instead, the part is insonified with unfocused chirped pulses and the transmitted A-scan is captured by a moving point-receiver. A computer-controlled rotating stage eliminates operator interaction during

S. G. Azevedo; J. P. Fitch; G. H. Thomas

1987-01-01

147

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

148

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

Microsoft Academic Search

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

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

1998-01-01

149

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

150

Wire Crimp Connectors Verification using Ultrasonic Inspection  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

151

Multi-Slice Parallel Transmission Three-Dimensional Tailored RF (PTX 3DTRF) Pulse Design for Signal Recovery in Ultra High Field Functional MRI  

PubMed Central

T2* weighted fMRI at high and ultra high field (UHF) is often hampered by susceptibility-induced, through-plane, signal loss. Three-dimensional tailored RF (3DTRF) pulses have been shown to be an effective approach for mitigating through-plane signal loss at UHF. However, the required RF pulse lengths are too long for practical applications. Recently, parallel transmission (PTX) has emerged as a very effective means for shortening the RF pulse duration for 3DTRF without sacrificing the excitation performance. In this article, we demonstrate a RF pulse design strategy for 3DTRF based on the use of multi-slice PTX 3DTRF to simultaneously and precisely recover signal with whole-brain coverage. Phantom and human experiments are used to demonstrate the effectiveness and robustness of the proposed method on three subjects using an eight-channel whole body parallel transmission system. PMID:23348046

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

2013-01-01

152

Profiling a reactor component using ultrasonics  

Microsoft Academic Search

The use of ultrasonic pulse echo ranging for profiling an inaccessible component in the complex and hostile structure of a nuclear reactor is described. The authors outline the ultrasonic method successfully employed in profiling a deformed guide tube of a reactor. The uniqueness of the method is the use of air transducers at 40 kHz, overcoming the inherent divergence problems

L. Pathak; V. R. Seshadri; C. Kumaravadivelu; G. Srinivasan; V. S. Raghunathan

1993-01-01

153

Ultrasonic thermometry in oil shale retorts  

Microsoft Academic Search

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

Ronchetto

1981-01-01

154

Ultrasonic flowmeter for gases. Final report  

Microsoft Academic Search

An ultrasonic flowmeter is developed for use in natural gas mains. The characteristics of the application and the dynamic head device presently employed are described. The performance requirements, design, and prototype testing of the ultrasonic instrument are discussed. The viability of a unique metering technique using reflected acoustic pulses was experimentally demonstrated. The flowmeter developed herein requires access to one

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

1984-01-01

155

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

156

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

157

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

158

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

PubMed

A hollow-fiber bundle was designed and used to deliver high-peak-power pulses from a Q-switched Nd:YAG laser. An 80 cm long bundle with a total diameter of 5.5 mm was composed of 37 glass capillaries with bore diameters of 0.7 mm. Beam-resizing optics with two lenses were used to couple the laser beam into the bundle. The measured coupling loss due to the limited aperture ratio of the bundle was 2.3 dB, and the transmission loss at wavelengths of 1064 and 532 nm was 0.3 dB. When an inert gas flowed through the bores of the capillaries, the maximum output pulse energy was 200 mJ, which was the limit of the laser used in the experiment. Hollow-fiber bundles withstand irradiation better than single hollow fibers and silica-glass optical fibers do. They are suitable for many dermatological applications because they can be used to irradiate a large area. PMID:16946798

Yilmaz, Ozgur; Miyagi, Mitsunobu; Matsuura, Yuji

2006-09-20

159

Ultrasonic Maintenance  

NASA Technical Reports Server (NTRS)

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

1991-01-01

160

WDM Transmission at 6-Tbit\\/s Capacity Over Transatlantic Distance, Using 42.7Gb\\/s Differential Phase-Shift Keying Without Pulse Carver  

Microsoft Academic Search

We report the transmission of a record 6 Tbit\\/s capacity over 6120 km distance, involving channels modulated at 42.7-Gb\\/s bit-rate with differential phase-shift keying (DPSK). The performance is found similar to DPSK with subsequent pulse carving, namely RZ-DPSK.

G. Charlet; E. Corbel; J. Lazaro; A. Klekamp; R. Dischler; P. Tran; W. Idler; H. Mardoyan; A. Konczykowska; F. Jorge; S. Bigo

2005-01-01

161

WDM transmission at 6 Tbit\\/s capacity over transatlantic distance, using 42.7Gb\\/s differential phase-shift keying without pulse carver  

Microsoft Academic Search

We report the transmission of a record 6 Tbit\\/s capacity over 6,120 km distance, involving channels modulated at 42.7 Gb\\/s bit-rate with differential phase-shift keying (DPSK). The performance is found similar to DPSK with subsequent pulse carving, namely RZ-DPSK.

G. Charlet; E. Corbel; J. Lazaro; A. Klekamp; R. Dischler; P. Tran; W. Idler; H. Mardoyan; A. Konczykowska; F. Jorge; S. Bigo

2004-01-01

162

Theory of magnetically insulated electron flows in coaxial pulsed power transmission lines  

NASA Astrophysics Data System (ADS)

The Cartesian magnetically insulated transmission line (MITL) theory of Mendel et al. [Appl. Phys. 50, 3830 (1979); Phys. Fluids 26, 3628 (1983)] is extended to cylindrical coordinates. A set of equations that describe arbitrary electron flows in cylindrical coordinates is presented. These equations are used to derive a general theory for laminar magnetically insulated electron flows. The laminar theory allows one to specify the potentials, fields, and densities across a coaxial line undergoing explosive electron emission at the cathode. The theory is different from others available in cylindrical coordinates in that the canonical momentum and total energy for each electron may be nonzero across the electron sheath. A nonzero canonical momentum and total energy for the electrons in the sheath allows the model to produce one-dimensional flows that resemble flows from lines with impedance mismatches and perturbing structures. The laminar theory is used to derive two new self-consistent cylindrical flow solutions: (1) for a constant density profile and (2) for a quadratic density profile of the form ?=?c[(r2m-r2)/(r2m-r2c)]. This profile is of interest in that it is similar to profiles observed in a long MITL simulation [Appl. Phys. 50, 4996 (1979)]. The theoretical flows are compared to numerical results obtained with two-dimensional (2-D) electromagnetic particle-in-cell (PIC) codes.

Lawconnell, Robert I.; Neri, Jesse

1990-03-01

163

PIC simulation and analytic modeling of both long and short-pulse magnetically insulated transmission lines  

SciTech Connect

It is crucial to have appropriate tools for MITL design. This need is emphasized by the number of new pulsed power accelerators presently in the feasibility-study and design stages. MITL systems are essential components of most of these accelerators. MITLs are typically modeled by Telegrapher`s equations that treat electrons only through a voltage and current-dependent loss front current. The electron flow behind the loss front in a MITL system must also be included adequately in a model if it is to accurately determine the power and energy available to the load of a MITL. Often electromagnetic, relativistic PIC simulations must be done to characterize specific MITL designs. However, rather than concentrate on simulations of a specific geometry, they have recently done ensembles of simulations of generic MITL systems and have found patterns in the results that validate the use of a generalized set of Telegrapher`s equations which include electron flow. The fit to this pattern provides the value of a parameter, determined by the electron dynamics, used in the model. The simulations have also demonstrated features whose assumption makes the analytic model very simple to implement. One of these simplifying assumptions is that the flow impedance is essentially constant, nearly independent of load impedance even in a short line. The new modeling equations should prove useful for the accurate characterization of MITLs, allowing one to easily predict load power and energy for a variety of system designs. The authors show a number of sample calculations from the model with corresponding simulation results for comparison.

Rosenthal, S.E.; Mendel, C.W. Jr. [Sandia National Labs., Albuquerque, NM (United States)

1994-12-31

164

The application of ultrasonic phased array system to the inspection of fillet weld of flat plate  

Microsoft Academic Search

The ultrasonic phased array inspection imaging system was developed in this paper, which is integrated on the basis of the each module and the exploitation of subsystem, it is made up of computer, ultrasonic circuit system, scanning device, phased array transducer and imaging software. The ultrasonic phased array inspection imaging system has the functions of controlling ultrasonic transmission and reception,

Baohua Shan; Hua Wang; Xin Wang; Zhongdong Duan; Jinping Ou

2007-01-01

165

Ultrasonic monitoring of food freezing  

Microsoft Academic Search

The time of flight of an ultrasonic pulse moving parallel to the direction of heat flux was measured in blocks of food (gelatin, chicken, beef) during freezing. Echoes were recorded from the food surfaces and from the moving ice front within the food. The changing return times of these echoes were used to calculate the percentage of the food frozen

Halldor Sigfusson; Gregory R. Ziegler; John N. Coupland

2004-01-01

166

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

167

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

168

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

169

Out-of-plane ultrasonic velocity measurement  

DOEpatents

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

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

1998-01-01

170

Ultrasonic Thermometry  

Microsoft Academic Search

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

L. C. Lynnworth; E. P. Papadakis

1970-01-01

171

Analysis of the development of a nanosecond pulsed corona on a two-wire transmission line using the method of q-v curves  

NASA Astrophysics Data System (ADS)

An indoor two-wire transmission line (TL) was used to investigate the development of corona discharge during the propagation of a short HV pulse, for both polarities. The pulse voltage peak ranged from 40 to 100 kV with a pulse width of 5 ns at the full-width half-maximum points. The charge per unit length q was derived from the measurement of the voltage and current at the beginning of the TL. The q-v hysteresis curves were used to analyze the properties of the corona developed along the TL. It was found that at peak voltages much higher than the corona onset voltage, the q-v curves' characteristics were similar to those found for ?s surge pulses at overhead transmission lines. For peak voltages close to the corona onset, the corona exhibited charge neutralization oscillations and the charge buildup delay time vanished. It was also found that the positive corona is up to about six times more dissipative than the negative one, even though the negative corona onset voltage was somewhat lower than the positive, and q at the peak voltage is similar for both polarities.

Nissim, N.; Ashkenazy, J.; Yankelevich, Y.; Baksht, R.; Pokryvailo, A.

2006-11-01

172

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

173

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

174

Pulse transformers  

Microsoft Academic Search

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

H. Lord

1971-01-01

175

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

NASA Astrophysics Data System (ADS)

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

Endoh, Nobuyuki; Yamamoto, Koji

1993-05-01

176

Ultrasonic thermometry in oil shale retorts  

SciTech Connect

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

Ronchetto, J.J.

1981-05-06

177

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

178

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

SciTech Connect

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

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

2004-02-26

179

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

180

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

Microsoft Academic Search

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

Óscar Martín; Manuel López; Fernando Martín

2007-01-01

181

Ultrasonic colour Doppler imaging  

PubMed Central

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

Evans, David H.; Jensen, J?rgen Arendt; Nielsen, Michael Bachmann

2011-01-01

182

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

183

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

NASA Astrophysics Data System (ADS)

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

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

2000-05-01

184

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

185

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

186

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

187

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

188

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

189

National Metal Casting Research Institute final report. Development of an automated ultrasonic inspection cell for detecting subsurface discontinuities in cast gray iron. Volume 3  

Microsoft Academic Search

This inspection cell consisted of an ultrasonic flaw detector, transducer, robot, immersion tank, computer, and software. Normal beam pulse-echo ultrasonic nondestructive testing, using the developed automated cell, was performed on 17 bosses on each rough casting. Ultrasonic transducer selection, initial inspection criteria, and ultrasonic flow detector (UFD) setup parameters were developed for the gray iron castings used in this study.

Burningham

1995-01-01

190

Coherent Brillouin spectroscopy in a strongly scattering liquid by picosecond ultrasonics  

E-print Network

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

Maznev, Alexei

191

Wire Crimp Termination Verification Using Ultrasonic Inspection  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

192

Delivering IEC 61000-4-2 current pulses through transmission lines at 100 and 330 ohm system impedances  

Microsoft Academic Search

Device testing using an IEC-compliant hand-held 150 pF\\/330 Omega discharge gun was compared to a 50 Omega IEC waveform pulser. Current waveforms were recorded and components tested with both pulsers. To understand effects of different pulse source impedances, the 50 Omega pulser was modified to operate at 100 and 330 Omega delivery impedances.

Evan Grund; Kathleen Muhonen; Nathaniel Peachey

2008-01-01

193

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

SciTech Connect

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

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

1988-11-01

194

Development of AN Ultrasonic Liquid Steel Inclusion Monitor  

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

195

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

196

Technique for measuring ultrasonic velocity and attenuation changes in attenuative materials at temperature such as during sintering processes  

NASA Astrophysics Data System (ADS)

This paper describes a PC-based automatic measuring system for ultrasonic velocity and attenuation changes in highly attenuating green-body ceramics during sintering temperatures. The system uses pulse-echo/through-transmission buffer rod technique and records pulse-echo and through-transmission waveforms at programmed time or temperature intervals. Data can be taken without interruption during temperature schedules lasting many days. Archival files of the waveform data are saved on disks for later analysis. Accuracy of the technique is demonstrated for solid fused silica for which dynamic resonance and Brillouin scattering data of the longitudinal velocity are compared at temperatures up to 1200 °C. The system has been used successfully for measuring longitudinal velocity and attenuation changes at 5 MHz during sintering of ZnO-based varistor materials and YBa2Cu3Ox superconducting ceramics.

Gieske, John H.; Frost, Harold M., III

1991-12-01

197

Production of aqueous spherical gold nanoparticles using conventional ultrasonic bath  

PubMed Central

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

2012-01-01

198

Production of aqueous spherical gold nanoparticles using conventional ultrasonic bath.  

PubMed

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

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

2012-01-01

199

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

SciTech Connect

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

Maris, J.H.; Tauc, J.

1992-05-01

200

Modeling of ultrasonic processing  

E-print Network

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

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

2005-01-01

201

System and method for ultrasonic tomography  

DOEpatents

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

Haddad, Waleed Sami (Dublin, CA)

2002-01-01

202

Ultrasonic assisted dyeing  

Microsoft Academic Search

The dyeing of wool fabrics using lac as a natural dye has been studied in both conventional and ultrasonic techniques. The extractability of lac dye from natural origin using power ultrasonic was also evaluated in comparison with conventional heating. The results of dye extraction indicate that power ultrasonic is rather effective than conventional heating at low temperature and short time.

M. M. Kamel; Reda M. El-Shishtawy; B. M. Yussef; H. Mashaly

2005-01-01

203

Opto-ultrasonic sounding system.  

PubMed

A new combination of pulsed ultrasonic waves and laser light with proper signal processing techniques is shown as a means of nondestructive testing. This method is suitable for inspection of the conditions in narrow, long regions, such as inside a pipe. The construction and basic experimental results are shown, and the effects of the signal processing are emphasized. As typical of the sensitivity of the system, an object 3 mm high placed at a 500-mm distance from the open aperture of a 26-mm diam pipe could be detected. PMID:20165156

Sato, T; Tsujimura, K; Ueda, M

1976-05-01

204

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

205

Pulse stretcher  

DOEpatents

Apparatus for increasing the length of a laser pulse to reduce its peak power without substantial loss in the average power of the pulse is disclosed. The apparatus uses a White cell having a plurality of optical delay paths of successively increasing number of passes between the field mirror and the objective mirrors. A pulse from a laser travels through a multi-leg reflective path between a beam splitter and a totally reflective mirror to the laser output. The laser pulse is also simultaneously injected through the beam splitter to the input mirrors of the optical delay paths. The pulses from the output mirrors of the optical delay paths go simultaneously to the laser output and to the input mirrors of the longer optical delay paths. The beam splitter is 50% reflective and 50% transmissive to provide equal attenuation of all of the pulses at the laser output. 6 figures.

Horton, J.A.

1994-05-03

206

Ultrasound transmission measurements through the os calcis.  

PubMed

A method of measuring ultrasonic propagation in the os calcis was devised for assessing bone properties in humans. Speed-of-sound (SOS) and broadband ultrasound attenuation (BUA) were measured using broadband acoustic pulses transmitted and received by a pair of focused transducers. The transducers are mounted coaxially in a water tank with the subject's heel in between. Reproducibility of results in an adult male was 10% for the BUA and 1.2% for the SOS. Both SOS and BUA changed when the transmission path through the os calcis was varied. For a population of normal male subjects, SOS and BUA were correlated with densitometry results on the os calcis, but less well correlated to area density at remote sites. PMID:1913288

Zagzebski, J A; Rossman, P J; Mesina, C; Mazess, R B; Madsen, E L

1991-08-01

207

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

208

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

209

Ultrasensitive ultrasonic transducer studies  

SciTech Connect

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

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

1996-09-01

210

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

211

Piezoelectric thick film ultrasonic transducers fabricated by a spray technique  

Microsoft Academic Search

Thick film broadband ultrasonic transducers (UTs) produced using sol-gel spray technique, operating below 10 MHz are presented. These UTs are formed by dispersing PZT and LiTaO3 particles, respectively in Al2O3 and PZT sol-gel solution. The 50-100 ?m thick films have been deposited on curved steel, flat steel and aluminum substrates and steel rods. Ultrasonic pulse-echo signals with a signal to

M. Kobayashi; T. R. Olding; L. Zou; M. Sayer; C.-K. Jen; A.-U. Rehman

2000-01-01

212

Lithium tantalate\\/lead zirconate titanate composite ultrasonic transducers  

Microsoft Academic Search

Lithium tantalate (LiTaO3)\\/lead zirconate titanate (PZT) ceramic films of thickness about 50 mum have been deposited on stainless-steel substrates using a modified sol-gel process. LiTaO3 powders are dispersed in a PZT sol-gel matrix to form a 0-3 ceramic\\/ceramic composite. The dielectric, electric, and piezoelectric properties have been studied. Ultrasonic pulse-echo measurements using the composite films as piezoelectric ultrasonic transducers demonstrate

Y. Chen; M. Sayer; L. Zou; C.-K. Jen

1999-01-01

213

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

214

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

215

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

216

Sonochemical Effect Using Ultrasonic Atomizer at 2.4 MHz  

NASA Astrophysics Data System (ADS)

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

Shinashi, Kiyoaki; Houkin, Toshinori; Harada, Hisashi

2012-07-01

217

Ultrasonic preamplifier performance evaluation  

Microsoft Academic Search

Paper is analyzing the ultrasonic preamplifiers performance comparison problem. Technique and equipment for ultrasonic preamplifier's performance evaluation and different manufacturers' products comparison has been established. Equipment used and measurement technologies applied are described and presented. Experimental results for the measured complex gain (magnitude and phase) of the preamplifier, the preamplifier equivalent input noise, and preamplifier input impedance (expressed as resistance

Linas Svilainis; Vytautas Dumbrava; Andrius Chaziachmetovas

2010-01-01

218

Chemical Effects of Ultrasonics  

Microsoft Academic Search

The present work was undertaken with the purpose of considering why and how reaction takes place in an ultrasonic field, rather than studying the chemical kinetics of such reactions. Experimental evidence is presented which supports the conclusions that chemical processes brought about by ultrasonics require cavitation. Furthermore, the experiments were planned so as to show whether the reactions take place

Mary Evelyn Fitzgerald; Virginia Griffing; James Sullivan

1956-01-01

219

Ultrasonic assisted-ECAP.  

PubMed

Equal channel angular pressing (ECAP) is one of the most prominent procedures for achieving ultra-fine grain (UFG) structures among the various severe plastic deformation (SPD) techniques. In this study, the effect of ultrasonic vibration on deformation behavior of commercial pure aluminum in the ECAP process is analyzed successfully using three dimensional (3D) by finite element methods (FEMs). The investigation includes the effects of die geometry, billet length, friction factor, ram speed, ultrasonic amplitude and ultrasonic frequency. Conventional as well as ultrasonic ECAP has been performed on aluminium 1070 alloy and the obtained data were used for validating simulations. It is observed that a 13% reduction in the average force was achieved when ultrasonic vibration with amplitude of 2.5 ?m at 20 kHz is applied. Also, further reduction in ECAP forming forces are obtained with increase of vibration amplitude, vibration frequency, friction factor, billet length and die channel angle. PMID:23523093

Djavanroodi, F; Ahmadian, H; Koohkan, K; Naseri, R

2013-08-01

220

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

Microsoft Academic Search

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

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

1991-01-01

221

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

222

Ultrasonic-aided fabrication of gold nanofluids  

Microsoft Academic Search

A novel ultrasonic-aided one-step method for the fabrication of gold nanofluids is proposed in this study. Both spherical-\\u000a and plate-shaped gold nanoparticles (GNPs) in the size range of 10-300 nm are synthesized. Subsequent purification produces\\u000a well-controlled nanofluids with known solid and liquid contents. The morphology and properties of the nanoparticle and nanofluids\\u000a are characterized by transmission electron microscopy, scanning electron

Hui-Jiuan Chen; Dongsheng Wen

2011-01-01

223

The 2004 Ultrasonic Benchmark Problem - SDH Response Under Oblique Incidence: Measurements and Patch Element Model Calculations  

SciTech Connect

The 2004 ultrasonic benchmark problem requires models to predict, given a reference pulse waveform, the pulse echo response of cylindrical voids of various radii located in an elastic solid for various incidence angles of a transducer immersed in water. We present the results of calculations based on the patch element model, recently developed at CNDE, to determine the response of an SDH in aluminum for specific oblique incidence angles. Patch element model calculations for a scan across the SDH, involving a range of oblique incidence angles, are also presented. Measured pulse-echo scans involving the SDH response under oblique incidence conditions are reported. In addition, through transmission measurements involving a pinducer as a receiver and an immersion planar probe as a transmitter under oblique incidence conditions are also reported in a defect-free Aluminum block. These pinducer-based measurements on a defect-free block are utilised to characterize the fields at the chosen depth. Comparisons are made between predictions and measurements for the pulse-echo response of a SDH.

Krishnamurthy, C. V.; Shankar, M.; Vardhan, J. Vishnu [Centre for NonDestructive Evaluation, Indian Institute of Technology, Chennai, India 600 036 (India); Balasubramaniam, Krishnan [Department of Mechanical Engineering, Indian Institute of Technology, Chennai, India 600 036 (India)

2006-03-06

224

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

225

Influence of gas law on ultrasonic behaviour of porous media under pressure  

Microsoft Academic Search

This paper deals with the influence of gas law on ultrasonic behaviour of porous media when the saturating fluid is high pressured. Previous works have demonstrated that ultrasonic transmission through a porous sample with variations of the static pressure (up to 18bars) of the saturating fluid allows the characterization of high damping materials. In these studies, the perfect gas law

S. Griffiths; C. Ayrault

2010-01-01

226

Ultrasonic drilling apparatus  

DOEpatents

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

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

1988-06-20

227

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

228

Method for the concurrent ultrasonic inspection of partially completed welds  

DOEpatents

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

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

2002-01-01

229

Ultrasonic wave propagation through a layer of spherical inclusions with random of periodic arrangements  

E-print Network

This thesis presents experimental results obtained by examining ultrasonic wave propagation through a layer of spherical lead inclusions embedded in a polyester matrix. Through transmission tests were conducted on several area fractions...

Day, Nathan Allan

2012-06-07

230

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

SciTech Connect

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

TL Murphy

2006-02-16

231

Pulse stretcher  

DOEpatents

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

Horton, James A. (Livermore, CA)

1994-01-01

232

Transmission electron microscopy studies of YBCO coated conductors prepared by pulsed-laser deposition and multiple-stage chemical vapor deposition processes  

NASA Astrophysics Data System (ADS)

Three types of YBCO films were deposited on metal tapes with biaxially textured CeO 2/Gd 2Zr 2O 7 multilayer. One YBCO film 4 ?m in thickness was formed by pulsed-laser deposition (PLD) on the stationary substrate and another film 3 ?m in thickness by PLD using a reel-to-reel substrate tape transferring system. Ic values of the films were 173 A and 293 A, respectively A further film 1 ?m in thickness was fabricated by multiple-stage chemical vapor deposition (MSCVD). The Ic value of the MSCVD-YBCO film was 100 A. The microstructures of these YBCO films were characterized using transmission electron microscopy (TEM). In the PLD-YBCO films, the films less than 1 ?m thick were predominantly composed of c-axis oriented grains which were considered to grow spirally, however, irregular instances of a-axis oriented grains were also found. The a-axis oriented grains size increased with increasing thickness of the YBCO films. In the 4 ?m-thick PLD-YBCO film with an Ic value of 173 A, a-axis oriented grains were considered to nucleate on the CeO 2. We found many Y 2O 3 and cupper oxides at the boundaries between a- and c-axes oriented grains and the orientation relationships between YBCO and Y 2O 3 were determined to be as follows: (0 0 1)YBCO//(0 0 1)Y 2O 3 and (1 0 0)YBCO//(1 1 0)Y 2O 3. We also found many gaps and pores between YBCO grains. Nucleation of a-axis oriented grains was completely suppressed on the CeO 2 in the 3 ?m-thick PLD-YBCO film with an Ic value of 293 A. In the MSCVD-YBCO film, the YBCO film mostly consisted of c-axis oriented grains, however a-axis oriented grains and polycrystal also formed in the film. As the MSCVD-YBCO film became thicker, the a-axis oriented grains grew large, as same as in the PLD-YBCO films. The growth rate of a-axis oriented grain along the substrate normal was much higher than that of c-axis oriented grains in comparison to the difference in the growth rate between a- and c-axes oriented grains in the PLD-YBCO. In these specimens, the grain growth of the a-axis oriented grains was considered to be one of the most significant causes of degradation of Jc values in the YBCO films.

Kato, Takeharu; Sasaki, Hirokazu; Iwai, Hiroyuki; Ibi, Akira; Kashima, Naoji; Niwa, Toshiharu; Muroga, Takemi; Miyata, Seiki; Watanabe, Tomonori; Iijima, Yasuhiro; Kakimoto, Kazuomi; Sutoh, Yasunori; Yamada, Yutaka; Nagaya, Shigeo; Saitoh, Takashi; Izumi, Teruo; Sasaki, Yukichi; Hirayama, Tsukasa; Shiohara, Yuh; Ikuhara, Yuichi

2005-10-01

233

Time domain attenuation estimation method from ultrasonic backscattered signals  

E-print Network

equation. The technique was assessed through simulations and validated through experiments with a tissue block size of 20 pulse lengths axially and 20 beamwidths laterally, the error in the attenuation values number(s): 43.80.Qf, 43.80.Vj, 43.80.Ev [TDM] Pages: 533­543 I. INTRODUCTION Ultrasonic wave propagation

Illinois at Urbana-Champaign, University of

234

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

235

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

236

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

237

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

238

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

239

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

PubMed

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

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

2006-12-22

240

Ultrasonic depth gauge for liquids under high pressure  

NASA Technical Reports Server (NTRS)

The invention relates to an ultrasonic depth gauge for liquids under high pressure and is particularly useful in the space industry where it is necessary to use a pressurized gas to transfer a liquid from one location to another. Conventional liquid depth gauges do not have the capability to operate under extreme high pressure (i.e., exceeding 300 psi). An ultrasonic depth gauge capable of withstanding high pressure according to the present invention is comprised of a transducer assembly and a supporting electronics unit. The former is mounted in to the bottom wall of a storage vessel with its resonating surface directly exposed to the highly pressurized liquid in the vessel. In operation, the ultrasonic pulse propagates upward through the liquid to the liquid-gas interface in the storage vessel. When the ultrasonic echo returns from the liquid-gas interface, it re-excites the composite resonator into vibration. The supporting electronics unit measures the round-trip transmit time for the ultrasonic pulse and its return echo to traverse the depth of the highly pressurized liquid. The novelty of the invention resides in the use of a conventional transducer rigidly bonded to the inside wall of a bored out conventional high-pressure plug to form a composite resonator capable of withstanding extremely high pressure.

Zuckerwar, Allan J. (inventor); Mazel, David S. (inventor)

1988-01-01

241

FREQUENCY DEPENDENT TORTUOSITY MEASUREMENT BY MEANS OF ULTRASONIC TESTS  

Microsoft Academic Search

The tortuosity is a fundamental parameter which gets involved in the description of the complexity of the path of the sound wave propagating within a porous material. Several methods have been developed to measure the tortuosity, based on electrical resistivity measurements, high frequency acoustic transmission and reflection measurement and ultrasonic tests. In the present work it has been developed an

Paolo Bonfiglio; Francesco Pompoli

242

On automated ultrasonic measurement system  

Microsoft Academic Search

The paper describes a fully automated system for measurement of the ultrasonic signals generated by ultrasonic transducers, designed for operating in air for a frequency range from 40 to 300 kHz. Study of new material's properties and sensitivity patterns for bio-mimetic ultrasonic transducers will be made. Measurements to estimate other important parameters of transducers will be possible as well. The

Silviu Epure; Radu Belea; Dorel Aiordachioaie; Razvan Solea

2011-01-01

243

Nondestructive Evaluation of Pavements Ultrasonic  

E-print Network

Nondestructive Evaluation of Pavements Ð Ultrasonic Tomography Kyle Hoegh, Graduate Student Dr. Lev:// pavementndt.weebly.com #12;Outline ·! Ultrasonic Tomography Overview ·! Georgia Example ·! MnROAD ­!Joint.weebly.com #12;Ultrasonic Methods: Pros and Cons ·! Advantages ­! Multiple applications ·! Thickness

Minnesota, University of

244

Soldering method using longitudinal ultrasonic  

Microsoft Academic Search

An efficient ultrasonic soldering method of inserting the metal bumps into the solder is investigated in this work for electronic packaging. The effects of the process parameters such as the ultrasonic frequency, amplitude, dimensions of the metal bump and solder are analyzed through the viscoelastic modeling. The ultrasonic soldering was conducted using the Cu and Au bumps, and the acceptable

Jung H. Kim; Jihye Lee; Choong D. Yoo

2005-01-01

245

A NOVEL ULTRASONIC THERMOMETRY FOR MONITORING TEMPERATURE PROFILES IN MATERIALS  

E-print Network

Abstract ? A new ultrasonic method for monitoring the temperature distribution inside a material being heated or cooled is presented. The principle of the method is based on the temperature dependence of the velocity of ultrasonic wave propagating through a material. An effective inverse analysis coupled with a finite difference calculation is used to determine the one-dimensional temperature distribution inside a thick plate. To verify the practical feasibility of the ultrasonic method, experiments have been demonstrated. A single side of a steel plate of 30 mm thickness is heated by contacting with a heater of 200 ºC and subsequently cooled down by water. Ultrasonic pulse-echo measurements are then performed for the steel during the heating and cooling. A change in the transit time of longitudinal ultrasonic waves across the steel is continuously acquired and used to determine the temperature distribution inside the steel. The temperature distribution and its transient variation determined by the ultrasonic method almost agree with those obtained using thermocouples installed in the steel. Thus, it is verified that the present method can be a promising means for real-time monitoring of temperature profiles in materials being heated or cooled.

Ikuo Ihara; Manabu Takahashi

2009-01-01

246

Ultrasonic Leak Detection System  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

247

Automated ultrasonic measuring system  

NASA Astrophysics Data System (ADS)

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

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

1987-01-01

248

Ultrasonic Processing of Materials  

SciTech Connect

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

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

2005-06-30

249

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

250

Ultrasonic verification of microstructural changes due to heat treatment  

NASA Technical Reports Server (NTRS)

Ultrasonic attenuation was measured for polycrystalline samples of nickel and copper with various grain-size distributions produced by heat treatment. Attenuation as a function of frequency was determined for a sample having a known mean grain diameter. Once this function was determined, it could be scaled to determine the mean grain size of other samples of the same material with different mean grain diameters. These results were obtained by using broadband pulse-echo ultrasound in the 25 to 100 MHz frequency range. The results suggest an ultrasonic, nondestructive approach for verifying heat treatment of metals.

Generazio, E. R.

1986-01-01

251

Lithium tantalate/lead zirconate titanate composite ultrasonic transducers  

NASA Astrophysics Data System (ADS)

Lithium tantalate (LiTaO3)/lead zirconate titanate (PZT) ceramic films of thickness about 50 ?m have been deposited on stainless-steel substrates using a modified sol-gel process. LiTaO3 powders are dispersed in a PZT sol-gel matrix to form a 0-3 ceramic/ceramic composite. The dielectric, electric, and piezoelectric properties have been studied. Ultrasonic pulse-echo measurements using the composite films as piezoelectric ultrasonic transducers demonstrate a broadband frequency response and good signal-to-noise ratio up to a temperature of 368 °C.

Chen, Y.; Sayer, M.; Zou, L.; Jen, C.-K.

1999-04-01

252

Generating Independent Preionizing Pulses for Lasers  

NASA Technical Reports Server (NTRS)

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

Pacala, T. J.

1986-01-01

253

ECG Gated Ultrasonic Small Animal Imaging.  

PubMed

Echocardiography is a routine clinical procedure to diagnose cardiac functions. The organic structure of the mouse is similar to that of human so that murine echocardiography has potentially become an effective tool for the assessment of human cardiovascular disease. However, clinical ultrasonic imaging systems are not suitable for murine cardiac imaging due to its limited spatial and temporal resolution. Thus, high frequency ultrasonic imaging (? 20 MHz) is necessary in order to provide spatial resolution at the order of 100 ?m. Furthermore, due to the lack of transducer arrays at such a high frequency, single-element transducer with mechanical scanning is typically used. Thus the frame rate is insufficient for imaging the quick motion of the mouse. In this paper, a high frequency ultrasonic imaging system with electrocardiography gating is built in order to provide both high spatial resolution and high temporal effecting resolution. The system utilizes the R-wave trigger signal from murine electrocardiography. Image data are acquired in either the block scanning mode or the line scanning mode. In block scanning, murine cardiac images in systole and diastole can be retrospectively reconstructed with a short data acquisition time. In line scanning, on the other hand, images during the entire cardiac cycle can be obtained. It is demonstrated that the effective frame rate can be up to 2 kHz, which is only limited by the pulse repetition rate of the system. PMID:17282556

Liu, Jian-Hung; Jeng, Geng-Shi; Wu, Tung-Ke; Li, Pai-Chi

2005-01-01

254

Ultrasonic Study of Dislocation Dynamics in Lithium -  

NASA Astrophysics Data System (ADS)

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

Han, Myeong-Deok

1987-09-01

255

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

Microsoft Academic Search

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

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

2002-01-01

256

Measurements of Ultrasonic Velocity of Erythrocyte Ghosts in Suspension with Sing-Around Method  

Microsoft Academic Search

An apparatus utilizing a sing-around method was constructed consisting of a pulse generator, a sample holder with transducers and a Schmitt circuit, in which ultrasonic velocity was determined from the period of pulses by an electronic counter with a relative accuracy of 10-6. The velocity V and the denisty rho were measured for suspensions of bovine erythrocyte ghosts in 150

Shigeki Mitaku; Akio Sakanishi; Akira Ikegami

1975-01-01

257

Laser ultrasonic microscopy  

Microsoft Academic Search

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

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

2011-01-01

258

Use of ultrasonic arrays for piping inspection  

Microsoft Academic Search

Ultrasonic inspection is frequently used to detect defects in structures during manufacturing, maintenance, and service. Traditionally the inspection is performed by manually or robotically scanning the surface with a single ultrasonic transducer. A flexible ultrasonic transducer array represents an innovative solution to many of the problems associated with traditional ultrasonic inspections. The flexible array consists of hundreds of ultrasonic pulser-receivers

Robert S. Frankle

1996-01-01

259

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

260

Parametric phase conjugation for the second harmonic of a nonlinear ultrasonic beam  

Microsoft Academic Search

The effect of phase conjugation for the second harmonic of a focused ultrasonic beam was investigated experimentally and by\\u000a numerical simulation. An ultrasonic pulse with the carrier frequency f=3 MHz was emitted into water and focused at a point between the source and the phase conjugating system. The phase conjugation\\u000a for the second harmonic of the incident wave (2f=6 MHz)

A. P. Brysev; F. V. Bunkin; M. F. Hamilton; R. V. Klopotov; L. M. Krutyanskii; K. Yan

2003-01-01

261

Piezoelectric thick film ultrasonic transducers fabricated by a sol–gel spray technique  

Microsoft Academic Search

Thick film broadband ultrasonic transducers (UTs) produced by a sol–gel spray technique and operated below 10 MHz are presented. These UTs are formed by dispersing PZT and LiTaO3 particles, respectively in Al2O3 and PZT sol–gel solution. The 50–100 ?m thick films have been deposited on curved steel, flat steel and aluminum substrates and steel rods. Ultrasonic pulse-echo signals with a

M Kobayashi; T. R Olding; M Sayer; C.-K Jen

2002-01-01

262

Transmission INTRODUCTION  

E-print Network

Transmission INTRODUCTION An electrical power system requires constant, second by second, balancing of supply, demand, and transmission capability. Transmission system operators are primarily responsible for maintaining this delicate balance. Transmission system operations are organized into "control areas," whose

263

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

264

In-flight measurement of ice growth on an airfoil using an array of ultrasonic transducers  

NASA Technical Reports Server (NTRS)

Results of preliminary tests to measure ice growth on an airfoil during flight icing conditions are presented. Ultrasonic pulse echo measurements of ice thickness are obtained from an array of eight ultrasonic transducers mounted flush with the leading edge of the airfoil. These thickness measurements are used to document the evolution of the ice shape during the encounter in the form of successive ice profiles. Results from 3 research flights are presented and discussed. The accuracy of the ultrasonic measurements is found to be within 0.5 mm of mechanical and stereo photograph measurements of the ice accretion.

Hansman, R. John, Jr.; Kirby, Mark S.; Mcknight, Robert C.; Humes, Robert L.

1988-01-01

265

Modeling of the ablation source in laser-ultrasonics  

NASA Astrophysics Data System (ADS)

For the excitation of ultrasound by optical irradiation two principal mechanisms play a role. One of them, the so-called thermoplastic effect has been quantitatively described by several groups. In this work, a quantitative model describing the second effect, the excitation of ultrasonic signals by evaporation of the surface of the material onto which the laser pulses impinges, is presented. The evaporation, the expansion of the evaporated material as well as the interaction with the optical radiation is treated in a one-dimensional model. The pressure exerted on the surface of the specimen which results from the expanding vaporized material is used as source for the generation of the ultrasonic signals in the material or component insonified. There is an optical intensity at which the broadband ultrasonic signals exhibit maximal amplitude. The amplitude of the ultrasonic signals calculated using the model presented and the amount of ablated material are compared with experimental results. Despite the simplifications made, the agreement between theory and experiment is excellent for steel and satisfactory for aluminum. The results of this work can be used to optimize the parameters for a laser-based ultrasonic inspection system.

Hoffmann, A.; Arnold, W.

2000-05-01

266

Ultrasonic classification of gallstones  

Microsoft Academic Search

The chemical composition of gallstones varies significantly, and the choice between nonsurgical treatment by dissolution and\\/or shock-wave lithotripsy depends on those properties. Acoustic imaging and measurements of acoustic attenuation using gated backscatter signals selected from the interior of gallstones between 4 and 6 mm in size have been accomplished with a high-frequency (30-MHz) ultrasonic system. Preliminary results indicate that gallstones

T. H. Lau; F. K. Forster; R. L. Baron

1989-01-01

267

Photodisruptive laser nucleation of ultrasonic cavitation for biomedical applications.  

PubMed

Pulses of high intensity laser light, when focused into transparent materials, may produce localized electron-ion plasmas through optical breakdown. By simultaneously incorporating the resulting volume of vaporized material within the focal volume of a high intensity ultrasound source, the photodisruption (1.05 microm wavelength) void served as a nucleation site for ultrasonic cavitation. Dilute suspensions of canine erythrocytes in phosphate buffered saline were exposed in a flow-through exposure chamber and the percentage of lysed cells was used as a measure of the biologically effective cavitation activity produced in the chamber. Brief (about 30 micros) acoustic emissions were detected from the photodisruption alone (indicating laser nucleation of bubbles), but the cell lysis produced was undetectable against the background. However, combined exposure greatly increased both the duration of the acoustic emissions (up to 1.5 ms) and the amount of cell lysis above an ultrasonic pressure amplitude threshold of about 4.3 MPa at 2.5 MHz. The amount of cell lysis (sometimes approaching 100%) increased with increasing ultrasonic intensity, laser pulse energy and laser PRF. Addition of 5% serum albumin enhanced the effect, apparently by stabilizing bubbles and nuclei. Photodisruptive laser nucleation of ultrasonic cavitation can provide controlled and synergistic enhancement of bioeffects. PMID:11516327

Miller, D L; Spooner, G J; Williams, A R

2001-07-01

268

Monitoring early age cementitious materials using ultrasonic guided waves  

NASA Astrophysics Data System (ADS)

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

Borgerson, Jacob L.

269

Ultrasonic wave velocity measurement in small polymeric and cortical bone specimens  

NASA Technical Reports Server (NTRS)

A system was refined for the determination of the bulk ultrasonic wave propagation velocity in small cortical bone specimens. Longitudinal and shear wave propagations were measured using ceramic, piezoelectric 20 and 5 MHz transducers, respectively. Results of the pulse transmission technique were refined via the measurement of the system delay time. The precision and accuracy of the system were quantified using small specimens of polyoxymethylene, polystyrene-butadiene, and high-density polyethylene. These polymeric materials had known acoustic properties, similarity of propagation velocities to cortical bone, and minimal sample inhomogeneity. Dependence of longitudinal and transverse specimen dimensions upon propagation times was quantified. To confirm the consistency of longitudinal wave propagation in small cortical bone specimens (< 1.0 mm), cut-down specimens were prepared from a normal rat femur. Finally, cortical samples were prepared from each of ten normal rat femora, and Young's moduli (Eii), shear moduli (Gij), and Poisson ratios (Vij) were measured. For all specimens (bone, polyoxymethylene, polystyrene-butadiene, and high-density polyethylene), strong linear correlations (R2 > 0.997) were maintained between propagation time and distance throughout the size ranges down to less than 0.4 mm. Results for polyoxymethylene, polystyrene-butadiene, and high-density polyethylene were accurate to within 5 percent of reported literature values. Measurement repeatability (precision) improved with an increase in the wave transmission distance (propagating dimension). No statistically significant effect due to the transverse dimension was detected.

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

1997-01-01

270

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

271

646 ULTRASONIC PHYSICAL MECHANISMS AND CHEMICAL EFFECTS ULTRASONIC PHYSICAL MECHANISMS  

E-print Network

pressure turnsspeed jets of liquid into the solid surface (5,13). These jets and associated shock waves can646 ULTRASONIC PHYSICAL MECHANISMS AND CHEMICAL EFFECTS ULTRASONIC PHYSICAL MECHANISMS AND CHEMICAL EFFECTS The irradiation of liquids with high-intensity ultrasound causes chemical reactions to occur (1

Suslick, Kenneth S.

272

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

273

Borehole data transmission apparatus  

DOEpatents

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

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

1993-01-01

274

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

275

Ultrasonic Assembly of Thermoplastic Parts  

Microsoft Academic Search

Four ultrasonic methods were evaluated for assembly of experimental plastic parts for detonators: (1) welding, (2) crimping and staking, (3) insertion, and (4) reactivation of adhesives. For welding, staking and insertion, plastics with low elastic moduli, such as acrylics and polycarbonate, produced the best results. Thermosetting, hot-melt, and solution adhesives could all be activated ultrasonically to form good bonds on

Schurman

1970-01-01

276

Acousto-ultrasonics - An update  

NASA Technical Reports Server (NTRS)

The application possibilities and limitations of acoustoultrasonics are reviewed. One of the most useful aspects of acousto-ultrasonics is its ability to assess degradation and damage states in composites. The sensitivity of the acousto-ultrasonic approach for detecting and measuring subtle but significant material property variations in composites has been demonstrated.

Vary, Alex

1989-01-01

277

Toward virtual biopsy through an all fiber optic ultrasonic miniaturized transducer: a proposal.  

PubMed

The present generation of devices based on opto-acoustic and acousto-optic conversion lets us foresee the possibility of realizing complete miniaturized transmitting-receiving transducers, able to generate and detect wideband ultrasounds by laser light. In the present paper, a miniaturized ultrasonic transducer entirely based on fiber optic technology is proposed. Such a device springs from the conjunction between our research, which has produced a highly efficient fiber optic opto-acoustic source, with the results obtained by other researchers concerning the realization of an ultrasonic receiver based on optical interferometry. Making use of the thermo-elastic effect for ultrasound generation, a source of ultrasound can be obtained by coupling a fiber optic to pulsed laser, if a film capable of absorbing laser light is placed onto fiber end. Starting from these remarks, we propose an efficient opto-acoustic source, able to generate pressure pulses with amplitude of the order of 10(4) Pa and bandwidth extending up to 40 MHz and beyond by using graphite materials as absorbing film. This solution makes use of a low-power pulsed laser as optical source possible. An ultrasonic receiving element was realized placing a Fabry-Perot cavity over the tip of a fiber optic. The cavity thickness modulation induced by ultrasonic beam is detected by an interferometer optical technique. We have realized a prototype of a receiving device that exhibits a sensitivity comparable with that of piezoelectric devices (10-100 nV/Pa) and an almost flat bandwidth extending up to 20 MHz or more. The extreme miniaturization of the resulting ultrasonic transducer, together with its wide ultrasonic frequency bandwidth, is the first step toward ultrasonic tissue biopsy. In this paper, before discussing the problem of constructing a complete ultrasonic transducer composed by a transmitter and receiver, the results carried out in these fields during the last decade are reviewed. PMID:14609072

Acquafresca, Alberto; Biagi, Elena; Masotti, Leonardo; Menichelli, David

2003-10-01

278

Ultrasonic flow nozzle cleaning apparatus  

SciTech Connect

This patent describes an ultrasonic cleaning apparatus for a venturi flow measuring nozzle mounted in a pipe of a steam power plant and having an inlet, venturi throat, and an outlet, the pipe and nozzle having fluid flowing therethrough, the cleaning occurring while the fluid is flowing. It comprises first ultrasonic transducer means mounted to connect to the inside of the pipe, disposed adjacent the inlet of the venturi flow nozzle and the means being in direct contact with the fluid flowing through the pipe for transmitting ultrasonic waves directly into and thereby exciting the fluid flowing through the venturi flow nozzle; and control means coupled to the first ultrasonic transducer means for activating the first ultrasonic transducer means.

Fridsma, D.E.; Silvestri, G.J. Jr.; Twerdochlib, M.

1992-06-23

279

Ultrasonic actuators for nanometre positioning  

PubMed

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

Snitka

2000-03-01

280

Effects of surface roughness on ultrasonic flaw signals  

NASA Astrophysics Data System (ADS)

In order to demonstrate the effect of random phase modulation on a well-collimated coherent ultrasonic beam, a simple computer simulation is run using the so-called angular-spectrum representation method. The experiments verify the conclusion derived from theoretical results that the ratio of the surface roughness induced transmission loss to the reflection loss at normal incidence is basically a simple constant determined by the sound velocities in the fluid and the solid. The normalized transmission loss is independent of both frequency and rms roughness. It is also almost entirely independent of the densities of the fluid and the solid and, at least in the two angular ranges of high practical importance in ultrasonic NDE, it is marginally sensitive to the autocorrelation length of the surface topography and to the angle of incidence.

Nagy, Peter B.; Adler, Laszlo; Rose, James H.

281

Pulse shaping system  

DOEpatents

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

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

1999-03-23

282

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

283

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

284

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

285

Design of embedded endoscopic ultrasonic imaging system  

Microsoft Academic Search

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

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

2008-01-01

286

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

287

Ultrasonic nondestructive characterization of composites with 3-dimensional architectures  

NASA Technical Reports Server (NTRS)

The development and implementation of advanced composite material systems and their associated technologies are critical for success in the highly competitive world aerospace market. Acceptance of advance production methods and field support of structures made with these new materials require the development of quantitative, cost-effective, inspection methods. The results of quantitative ultrasonic through-transmission imaging of composites with complex three-dimensional architecture using phase-insensitive and phase-sensitive techniques are presented.

Miller, James G.

1992-01-01

288

Ultrasonics and space instrumentation  

NASA Technical Reports Server (NTRS)

The design topic selected was an outgrowth of the experimental design work done in the Fluid Behavior in Space experiment, which relies on the measurement of minute changes of the pressure and temperature to obtain reasonably accurate volume determinations. An alternative method of volume determination is the use of ultrasonic imaging. An ultrasonic wave system is generated by wall mounted transducer arrays. The interior liquid configuration causes reflection and refraction of the pattern so that analysis of the received wave system provides a description of the configuration and hence volume. Both continuous and chirp probe beams were used in a laboratory experiment simulating a surface wetting propellant. The hardware included a simulated tank with gaseous voids, transmitting and receiving transducers, transmitters, receivers, computer interface, and computer. Analysis software was developed for image generation and interpretation of results. Space instrumentation was pursued in support of a number of experiments under development for GAS flights. The program included thirty undergraduate students pursuing major qualifying project work under the guidance of eight faculty supported by a teaching assistant. Both mechanical and electrical engineering students designed and built several microprocessor systems to measure parameters such as temperature, acceleration, pressure, velocity, and circulation in order to determine combustion products, vortex formation, gas entrainment, EMR emissions from thunderstorms, and milli-g-accelerations due to crew motions.

1987-01-01

289

Ultrasonic Lamb wave tomography  

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

290

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

291

Hemolysis in vivo from exposure to pulsed ultrasound  

Microsoft Academic Search

Ultrasonically induced hemolysis in vivo was studied when a commercial ultrasound contrast agent, Albunex®, was present in the blood. Murine hearts were exposed for 5 min at either 1.15 or 2.35 MHz with a pulse length of 10 ?s and pulse repetition frequency of 100 Hz. During the exposure period, four boluses of Albunex® were injected into a tail vein

D. Dalecki; C. H. Raeman; S. Z. Child; C. Cox; C. W. Francis; R. S. Meltzer; E. L. Carstensen

1997-01-01

292

8. Transmission 52 8. Transmission  

E-print Network

8. Transmission 52 ___________________________________________________________________________ 8. Transmission 8.1 Introduction The classical approach for calculations of structure-borne sound and vibration transmission is based on the assumption of a source performing rigid body motions. A multi- point coupling

Berlin,Technische Universität

293

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

PubMed

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

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

2007-10-01

294

On-Line Measurement of Lubricant Film Thickness Using Ultrasonic Reflection Coefficients  

NASA Astrophysics Data System (ADS)

The ultrasonic reflectivity of a lubricant layer between two solid bodies depends on the ultrasonic frequency, the acoustic properties of the liquid and solid, and the layer thickness. In this paper, ultrasonic reflectivity measurements are used as a method for determining the thickness of lubricating films in bearing systems. An ultrasonic transducer is positioned on the outside of a bearing shell such that the wave is focused on the lubricant film layer. For a particular lubricant film the reflected pulse is processed to give a reflection coefficient spectrum. The lubricant film thickness is then obtained from either the layer stiffness or the resonant frequency. The method has been validated using static fluid wedges and the elastohydrodynamic film formed between a ball sliding on a flat. Film thickness values in the range 50-500 nm were recorded which agreed well with theoretical film formation predictions.

Drinkwater, B. W.; Dwyer-Joyce, R. S.; Harper, P.

2004-02-01

295

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

296

Ultrasonic cleavage of thioethers.  

PubMed

The rates of DPPH (diphenylpicrylhydrazyl) trapping and the sonolytical products obtained during the sonolysis of thioethers at normal and low temperature are reported. CS2, lower sulfides, thiophene, and sulfurized species are the common products during the ultrasonic irradiations. Hydrocarbons are also obtained during the sonolysis of diallyl sulfide, diethyl disulfide, and dipropyl disulfide. Furthermore, aldehydes are obtained as oxidized species; SO2 is found at 208 K. The principal sonochemical process appears to be the cleavage of C-S or S-S bond with secondary combinations and rearrangements. DPPH has been used to probe the sonolytical potential of thioethers. The results show a good correlation between the rates of DPPH trapping and the vapor pressures of thioethers. In conclusion, a lower vapor pressure results in a higher sonolytical rate. The sonochemical behaviors of thioethers have strong qualitative similarities to the pyrolysis. PMID:16839045

Wu, Zhilin; Ondruschka, Bernd; Stark, Annegret

2005-04-28

297

The Efficacy of Ultrasonic Cleansing.  

National Technical Information Service (NTIS)

Resin blocks containing simulated root canal spaces were compared with extracted teeth as models for the efficiency of endodontic debridement with hand instrumentation, ultrasonication and a combination of both techniques. Canal spaces were filled with ra...

R. N. Weller, J. M. Brady, W. E. Bernier

1979-01-01

298

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

299

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

300

Ultrasonic Evaluation of Deeply Located Trabecular Bones - Preliminary Results  

NASA Astrophysics Data System (ADS)

The analysis of ultrasonic signals scattered by soft tissues have been successfully applied for their characterization. Similarly, the trabecular bone backscattered signal contains information about the properties of the bone structure. Therefore scattering-based ultrasonic technique potentially enables the assessment of microstructure characteristics of a bone. The femoral neck fracture often occurs in the course of osteoporosis and can lead to severe complications. Therefore assessment of femoral bone microstructure and condition is important and essential for the diagnosis and treatment monitoring. As far most of the trabecular bone investigations have been performed in vitro. The only in vivo measurements were carried out in transmission and mostly concerned estimation of the attenuation in heel bone. We have built the ultrasonic scanner that could be useful in acquiring the RF (Radio Frequency) echoes backscattered by the trabecular bone in vivo. Moreover, the bone scanner provides data not only from heel bone but from deeply located bones as well (e.g. femoral bone). It can be also used for easily accessible bones like heel bone or breastbone. In this case a gel-pad is applied to assure focusing of ultrasound in trabecular bone (approximately 10 mm beneath the cortical bone). This study presents preliminary results of the attenuating properties evaluation of trabecular bone from the ultrasonic echoes backscattered by heel bone and femoral neck.

Cie?lik, Lucyna; Litniewski, Jerzy

301

Time domain attenuation estimation method from ultrasonic backscattered signals  

PubMed Central

Ultrasonic attenuation is important not only as a parameter for characterizing tissue but also for compensating other parameters that are used to classify tissues. Several techniques have been explored for estimating ultrasonic attenuation from backscattered signals. In the present study, a technique is developed to estimate the local ultrasonic attenuation coefficient by analyzing the time domain backscattered signal. The proposed method incorporates an objective function that combines the diffraction pattern of the source/receiver with the attenuation slope in an integral equation. The technique was assessed through simulations and validated through experiments with a tissue mimicking phantom and fresh rabbit liver samples. The attenuation values estimated using the proposed technique were compared with the attenuation estimated using insertion loss measurements. For a data block size of 15 pulse lengths axially and 15 beamwidths laterally, the mean attenuation estimates from the tissue mimicking phantoms were within 10% of the estimates using insertion loss measurements. With a data block size of 20 pulse lengths axially and 20 beamwidths laterally, the error in the attenuation values estimated from the liver samples were within 10% of the attenuation values estimated from the insertion loss measurements. PMID:22779499

Ghoshal, Goutam; Oelze, Michael L.

2012-01-01

302

Measurement of low-frequency ultrasonic wave in water using an acoustic fiber sensor.  

PubMed

An acoustic fiber sensor for measurement of ultrasonic waves, which used the approximate Raman-Nath diffraction effect where light diffraction waves were generated in an optical fiber by strain due to the ultrasonic waves, was proposed and examined. In order to characterize the acoustic fiber sensor as a basic study, measurements of low-frequency ultrasonic waves in water were examined using a step index fiber operating as a detection sensor. The results showed that characteristics of detected signals agreed with the theoretical prediction based on Fraunhofer diffraction. This indicates that our proposed fiber sensor can be used for the detection of low-frequency ultrasonic waves as well as the transmission of light diffraction signals. PMID:16615580

Sakoda, Tatsuya; Sonoda, Yoshito

2006-04-01

303

Doppler effect-based fiber-optic sensor and its application in ultrasonic detection  

NASA Astrophysics Data System (ADS)

Based on the Doppler effect of light wave transmission in optical fiber, Doppler effect-based fiber-optic (FOD) sensor possesses outstanding advantages in acquiring vibration/acoustic waves with high sensitivity. Furthermore, when shape of the FOD sensor was properly selected, its sensitivity was bonding direction-independent, namely non-directionality. In this paper, characteristics of the FOD sensor were investigated for the purpose of ultrasonic detection. A piezoelectric wafer was applied as an actuator to excite Lamb waves, a kind of ultrasonic wave, in an aluminum-alloy plate. Features of the ultrasonic wave signals, collected using a number of spiral FOD sensors with various inner diameters and outer diameters, were compared to investigate characteristics of FOD sensor. Amplitude curves of the FOD sensors were hereby obtained for the future applications in ultrasonic acquisition. The results demonstrated that sensitivity of the spiral FOD sensor with longer optical fiber length was higher than that with shorter fiber length.

Li, Fucai; Murayama, Hideaki; Kageyama, Kazuro; Shirai, Takehiro

2009-06-01

304

Development of Multiple-Frequency Ultrasonic Imaging System Using Multiple Resonance Piezoelectric Transducer  

NASA Astrophysics Data System (ADS)

The authors have developed a multiple frequency imaging system using a multiple resonance transducer (MRT) consisting of 1-3 composite materials with a low mechanical quality factor Q bonded together. The MRT has a structure consisting of thin and thick piezoelectric plates, two matching layers, and a backing layer. This makes it possible to obtain B-mode images of satisfactory resolution using ultrasonic pulses owing to their short duration. In this paper, the vibration property of the MRT derived through equivalent-circuit analysis is first shown. By utilizing the result, an MRT capable of transmitting ultrasonic pulses for generation of the images of biological tissues with satisfactory resolution is designed and prototyped. Setting the prototype transducer in the mechanical sector probe of commercial ultrasonic diagnosis equipment, the speckle reduction effect is demonstrated using images of various phantoms to mimic biological tissues and a human thyroid.

Akiyama, Iwaki; Yoshizumi, Natsuki; Saito, Shigemi; Wada, Yuji; Koyama, Daisuke; Nakamura, Kentaro

2012-07-01

305

Ultrasonic measurement of elastic moduli of 17-4 pH stainless steel and uranium -2 molybdenum from -40/sup 0/C to 800/sup 0/C  

SciTech Connect

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/sup 0/C to 800/sup 0/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 the specimen. Microstructural changes and phase transitions in the specimens are evident from the temperature dependence of the ultrasonic data. 10 figures, 3 tables.

Gieske, J. H.

1980-10-01

306

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

307

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

308

Principles and Application of Ultrasonic Spectroscopy in NDE of Adhesive Bonds  

Microsoft Academic Search

Ultrasonic spectroscopy utilizes the principle of construc- tive and destructive wave interferences to obtain information about ultrasound in the frequency domain. For applications in the nondes- tructive evaluation (NDE) of adhesive-bonded structures, destructive interference of the pulsed sound waves at the boundaries of the adhesive bond layer produces spectroscopic signals characteristic of the bond. The bondline thickness can be determined

FRANCIS H. CHANG; PAUL L. FLYNN; DAVID E. GORDON; JERRY R. BELL

1976-01-01

309

Wide-Area Imaging of Ultrasonic Lamb Wave Fields by Electronic Speckle Pattern Interferometry  

E-print Network

. K.-J. Pohl et a1113' described a pulsed holographic system for imaging laser generated RayleighWide-Area Imaging of Ultrasonic Lamb Wave Fields by Electronic Speckle Pattern Interferometry Grant vibration data collected via electronic speckle pattern interferometry used in combination with laser

Mast, T. Douglas

310

Sparsity enhancement for blind deconvolution of ultrasonic signals in nondestructive testing application  

Microsoft Academic Search

The received signal in ultrasonic pulse-echo inspection can be modeled as a convolution between an impulse response and the reflection sequence, which is the impulse characteristic of the inspected object. Deconvolution aims at approximately inverting this process to improve the time resolution so that the overlap between echoes from closely spaced reflectors becomes small. This paper presents a modified minimum

Liang Wei; Lei Hua-Ming; Que Pei-Wen

2008-01-01

311

DEVELOPMENT OF AN ULTRASONIC NDT SYSTEM FOR AUTOMATED IN-SITU INSPECTION OF WIND TURBINE BLADES  

E-print Network

DEVELOPMENT OF AN ULTRASONIC NDT SYSTEM FOR AUTOMATED IN- SITU INSPECTION OF WIND TURBINE BLADES Abington, Cambridge, CB21 6AL, UK bic@brunel.ac.uk ABSTRACT It is crucial to maintain wind turbine blades. This work investigates using pulse-echo ultrasound to detect internal damages in wind turbine blades without

Boyer, Edmond

312

Bayesian separation of Lamb wave signatures in laser ultrasonics  

NASA Astrophysics Data System (ADS)

Laser-based ultrasonic (LBU) measurement shows great promise for on-line monitoring of weld quality in tailor-welded blanks. Tailor-welded blanks are steel blanks made from plates of differing thickness and/or properties butt-welded together; they are used in automobile manufacturing to produce body, frame, and closure panels. LBU uses a pulsed laser to generate the ultrasound and a continuous wave laser interferometer to detect the ultrasound at the point of interrogation to perform ultrasonic inspection. LBU enables in-process measurements since there is no sensor contact or near-contact with the workpiece. The authors are using laser-generated plate waves to propagate from one plate into the weld nugget as a means of detecting defects.

Kercel, Stephen W.; Klein, Marvin B.; Pouet, Bruno F.

2000-03-01

313

Ultrasonic speech translator and communications system  

SciTech Connect

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 includes an ultrasonic transmitting device and an ultrasonic receiving device. The ultrasonic transmitting device accepts as input an audio signal such as human voice input from a microphone or tape deck. The ultrasonic transmitting device 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 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. 7 figs.

Akerman, M.A.; Ayers, C.W.; Haynes, H.D.

1996-07-23

314

Comparative analysis of small versus large transducers for high-frequency ultrasonic testing of breast cancer.  

PubMed

High-frequency ultrasound (20-80 MHz) has been found to be sensitive to margin pathology from breast cancer surgery. In order to improve the resolution and sensitivity of this method, transducers are needed that have smaller piezoelectric elements than those currently in use. This study's purpose was to determine if small-element transducers (Blatek, 50 MHz, diameter <2 mm) produce similar results as those from large-element transducers (Olympus NDT, 50 MHz, 6.35-mm diameter). Pulse-echo and through-transmission measurements were performed on bovine heart tissue and 10 phantom specimens containing chopped nylon fibers and polyethylene microspheres. The density of peaks in the ultrasonic spectra of the small or mini transducers (MT) paralleled those of the large transducers (LT) in the bovine tissue, with higher peak densities associated with connective tissue and lower peak densities with muscle tissue. The MT data from the phantoms showed greater variance than the LT data, indicating that the MT were more sensitive to the heterogeneous wavefields arising from microsphere scattering. Additional in vivo testing is currently being performed on breast tumors grown in mice treated with Avastin. Small-element transducers may ultimately provide in vivo cancer detection in margins, allowing more precise excision of cancerous tissue and thus eliminating follow-up surgeries. PMID:25235054

Peterson, Madison J; Bliss, Nathan M; Doyle, Timothy E

2014-04-01

315

A web-based tutorial for ultrasonic attenuation measurement  

NASA Astrophysics Data System (ADS)

An ultrasonic attenuation-versus-frequency curve can serve as an "ultrasonic signature" which may be correlated with microstructural properties of interest such as grain size in metals or porosity level in composites. Attenuation also plays a role in ultrasonic inspections and is consequently a key input into many inspection simulation models. A web-based self-tutorial on practical attenuation measurements is under development. The focus is on pulse/echo immersion measurements made using a broadband transducer to deduce attenuation within the transducer's useable bandwidth. Two approaches are considered: one using a calibration specimen having a known attenuation curve, and one without. In the first approach a back-wall (BW) echo in the calibration specimen is compared with a BW echo in the test specimen. In the second approach various BW reverberation echoes in the test specimen are compared with one another or with a front-wall echo. The web-based tutorial incorporates three classes of materials. The first includes written documentation and videos describing the measurement setups, the data-acquisition and analysis procedures, and the underlying models use to analyze the raw UT data. Secondly, general purpose "stand-alone" data-analysis software is supplied that is designed to be used with any ultrasonic inspection system that can output A-scan data as a text file. This includes both FORTRAN software and Excel spreadsheet calculators that accept A-scan text data as inputs. Thirdly, we supply demonstration software where the data acquisition and analysis procedures are integrated with a specific class of commercial ultrasonic test instruments, namely those running UTEX Winpect control software. This paper provides an overview of the measurement methods and tutorial materials. We also present early results from round-robin trials in which selected metal and composite specimens are being sent to participating partners for attenuation measurement.

Margetan, Frank J.; Barnard, Dan; Orman, David; Feygin, Alex; Pavel, Brittney

2014-02-01

316

Shingles Transmission  

MedlinePLUS

... on Shingles Immunization Action Coalition Chickenpox Q&As Transmission Language: English Español (Spanish) Share Compartir Español: ... Prevention & Treatment Related Pages Preventing Varicella Zoster Virus Transmission in Healthcare Settings Related Links Medline Plus NIH ...

317

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...

318

Ultrasonic cure monitoring of advanced composites  

SciTech Connect

Measurements of the ultrasonic sound speed of thermosetting resins and composites can be used as an in-process cure monitoring technique. Ultrasonic measurements have an advantage over other in-process techniques in that ultrasonic sensors do not make contact with the part (thus leaving no imbedded sensor or witness mark) and can make true bulk measurements of the part. A new commercially available ultrasonic cure monitoring system for the cure monitoring of thermosetting resins and composites has been developed. Advancements in ultrasonic sensor technology enable the self-contained ultrasonic sensor to be easily installed in a mold and maintain good coupling to the part during thermal cycling to 260{degrees}C. Data is presented showing the chance in ultrasonic sound speed during the compression molding of epoxy prepregs. The data shows a good relationship to the electrical resistivity data collected via dielectric cure monitoring. The ultrasonic technique is also applicable to phenolic based materials.

Shepard, D.D.; Smith, K.R.

1997-12-31

319

Ultrasonic Tests. Pt. 2. Advanced Techniques.  

National Technical Information Service (NTIS)

After a basic treatment of ultrasonic wave propagation, of the state-of-the-art methods and the technical background in the preceeding part, advanced ultrasonic NDT techniques are presented here. The discussion of new development includes - manipulation s...

K. Goebbels

1980-01-01

320

21 CFR 890.5300 - Ultrasonic diathermy.  

Code of Federal Regulations, 2011 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5300 Ultrasonic diathermy...Ultrasonic diathermy for use in applying therapeutic deep heat for selected medical...

2011-04-01

321

21 CFR 890.5300 - Ultrasonic diathermy.  

Code of Federal Regulations, 2012 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5300 Ultrasonic diathermy...Ultrasonic diathermy for use in applying therapeutic deep heat for selected medical...

2012-04-01

322

21 CFR 890.5300 - Ultrasonic diathermy.  

Code of Federal Regulations, 2013 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5300 Ultrasonic diathermy...Ultrasonic diathermy for use in applying therapeutic deep heat for selected medical...

2013-04-01

323

21 CFR 890.5300 - Ultrasonic diathermy.  

...SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5300 Ultrasonic diathermy...Ultrasonic diathermy for use in applying therapeutic deep heat for selected medical...

2014-04-01

324

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

325

Ultrasonic Time Reversal Mirrors  

NASA Astrophysics Data System (ADS)

For more than ten years, time reversal techniques have been developed in many different fields of applications including detection of defects in solids, underwater acoustics, room acoustics and also ultrasound medical imaging and therapy. The essential property that makes time reversed acoustics possible is that the underlying physical process of wave propagation would be unchanged if time were reversed. In a non dissipative medium, the equations governing the waves guarantee that for every burst of sound that diverges from a source there exists in theory a set of waves that would precisely retrace the path of the sound back to the source. If the source is pointlike, this allows focusing back on the source whatever the medium complexity. For this reason, time reversal represents a very powerful adaptive focusing technique for complex media. The generation of this reconverging wave can be achieved by using Time Reversal Mirrors (TRM). It is made of arrays of ultrasonic reversible piezoelectric transducers that can record the wavefield coming from the sources and send back its time-reversed version in the medium. It relies on the use of fully programmable multi-channel electronics. In this paper we present some applications of iterative time reversal mirrors to target detection in medical applications.

Fink, Mathias; Montaldo, Gabriel; Tanter, Mickael

2004-11-01

326

Ultrasonic enhancement of chemical cleaning of steam generators  

NASA Astrophysics Data System (ADS)

The results of an investigation into the use of ultrasound to enhance the chemical cleaning of steam generator tube and support crevices are presented. Primary attention was focused on a configuration with ultrasonic transducers in the downcomer region of the steam generator in conjunction with the EPRI Steam Generator Owners Group (SGOG) crevice solvent at 200 F. The investigation consisted primarily of experiments conducted in facilities designed to simulate the geometry and acoustics of a steam generator. The largest facility holds approximately 1000 gallons of solvent and simulates a 40 deg sector of a steam generator with two support plates. The testing demonstrated that ultrasonics is indeed an effective means of enhancing the crevice cleaning if sound levels sufficient to cause cavitation can be transmitted to the crevices. The effort focused on the coupling of the transducers to the wrapper plate, on the transmission of sound through the tube bundle, and on the determination of cavitation threshold levels.

Scharton, T.

1983-04-01

327

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

328

Antimicrobial activity of ultrasonic cleaners.  

PubMed

This study assessed the antimicrobial activity of two cleaning solutions and tap water after varying periods of use in one ultrasonic cleaner. Testing involved filling the cleaner's tank and a centred glass beaker with the same test solution. An aluminium foil strip test first determined that no significant differences in cavitational activity existed inside the beaker compared with outside. Standardized solutions of Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella choleraesuis were left at room temperature for 10 min. Aliquots were exposed to both cleaning solution and ultrasonic action. Unused test solution was removed from the tank, filter-sterilized, mixed with bacterial suspension and placed into a sterile beaker. Cleaning was allowed for 10 min. The beaker was removed and its contents examined. The tank was allowed to cool for 30 min and the process was repeated four times. The entire experimental set was repeated once. Exposure to test solution alone in all but one case produced reductions in bacterial numbers from initial >/=2 x 10(9) by 19.9-52.6%. Application of both chemical exposure and ultrasonic cleaning produced greater bacterial kill (46.4-99.7% reductions). However, kill became less effective on repeated use of a commercial cleaning solution. Reduction was highest when fresh ultrasonic cleaning solutions were used. In no case did complete sterilization occur. As well as removing adherent material, ultrasonic cleaning may also markedly reduce the number of viable organisms present. PMID:15949617

Muqbil, I; Burke, F J T; Miller, C H; Palenik, C J

2005-07-01

329

Ultrasonic Measurement Of Elastic Constants Of Composites  

NASA Technical Reports Server (NTRS)

Ultrasonic testing system yields data on elastic constants of matrix/fiber laminated composite material. Related to one described in "Ultrasonic System Measures Elastic Properties of Composites" (NPO-18729). Tests performed nondestructive, and involve access by ultrasonic probes to only one side of material specimen. In comparison with other available ultrasonic testing systems, this system relatively inexpensive, and based on testing technique that is simpler and rapidly yields more-accurate results.

Bar-Cohen, Yoseph; Mal, Ajit K.

1994-01-01

330

Ultrasonic estimate of the modulus of rupture and quantification of the frequency dependent dynamic modulus in Norway Spruce  

NASA Astrophysics Data System (ADS)

Ultrasonic measurements allow non-destructive evaluation of mechanical properties of wood. However, it is unclear how these ultrasonically determined properties relate to comparable values obtained by traditional mechanical experiments, e.g., three point bending performed at different probing frequencies. In addition, although a link between the modulus of rupture (MOR) and the modulus of elasticity (MOE) obtained with static methods is established, little research exists on the correlation between the ultrasonically determined dynamic elastic modulus and MOR. Therefore, we set out to link the modulus values obtained by three-point bending to those obtained by ultrasonic measurements at different frequencies. We compared the modalities using a fractional derivative model that theoretically predicts a frequency dependency of the dynamic elastic modulus. We determined MOE and MOR in 102 Norway Spruce samples (340 to 510 kg/m3 density) by three-point bending followed by ultrasonic through-transmission measurements that quantified the dynamic modulus at 500 kHz, 4 MHz, and 8 MHz. This is the first report on such a frequency series for Norway Spruce. Our results provide a conversion factor that permits comparing ultrasonically and statically measured MOE values. Depending on the ultrasonic frequency, correlations ranging from 0.3 to 0.53 between the ultrasonic dynamic modulus and MOR were found.

Salmi, Ari; Karppinen, Timo; Montonen, Risto; Saranpää, Pekka; Hæggström, Edward

2013-01-01

331

Reliability analysis of laser ultrasonics for train axle diagnostics based on model assisted POD curves  

NASA Astrophysics Data System (ADS)

High speed train axles are integrated for a lifetime and it is time and resource consuming to conduct in service inspection with high accuracy. Laser ultrasonics is a proposed solution as a subset of non-contact measuring methods effective also for hard to reach areas and even recently proved to be effective using Laser Doppler Vibrometer (LDV) or air-coupled probes in reception. A reliability analysis of laser ultrasonics for this specific application is here performed. The research is mainly based on numerical study of the effect of high energy laser pulses on the surface of a steel axle and of the behavior of the ultrasonic waves in detecting possible defects. Probability of Detection (POD) concept is used as an estimated reliability of the inspection method. In particular Model Assisted Probability of Detection (MAPOD), a modified form of POD where models are used to infer results for making a decisive statistical approach of POD curve, is here adopted. This paper implements this approach by taking the inputs from limited experiments conducted on a high speed train axle using laser ultrasonics (source pulsed Nd:Yag, reception by high-frequency LDV) to calibrate a multiphysics FE model and by using the calibrated model to generate data samples statistically representative of damaged train axles. The simulated flaws are in accordance with the real defects present on the axle. A set of flaws of different depth has been modeled in order to assess the laser ultrasonics POD for this specific application.

Malik, M. S.; Cavuto, A.; Martarelli, M.; Pandarese, G.; Revel, G. M.

2014-05-01

332

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

333

Broadband ultrasonic attenuation imaging: A new imaging technique of the os calcis  

Microsoft Academic Search

Ultrasound transmission measurement through the os calcis is an emerging technique and a promising clinical tool for early assessment of osteoporosis. However, several previous studies showed that broadband ultrasonic attenuation (BUA) is sensitive to small variations in bone mass or structure. The os calcis is an inhomogeneous bone and therefore, the attenuation depends on the location in the os calcis.

P. Laugier; P. Giat; G. Berger

1994-01-01

334

MEASUREMENT AND CORRECTION OF ULTRASONIC ANEMOMETER ERRORS  

E-print Network

MEASUREMENT AND CORRECTION OF ULTRASONIC ANEMOMETER ERRORS AND IMPACT ON TURBULENCE MEASUREMENTS-3206, email: office@ehf.uni-oldenburg.de http://www.physik.uni-oldenburg.de/ehf Ultrasonic anemometers commonly show systematic errors depending on wind speed due to inaccurate ultrasonic transducer mounting

Heinemann, Detlev

335

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

336

Laser ultrasonic investigations of vertical Bridgman crystal growth  

NASA Astrophysics Data System (ADS)

The many difficulties associated with the growth of premium quality CdTe and (Cd,Zn)Te alloys has stimulated an interest in the development of a non-invasive ultrasonic approach to monitor critical growth parameters such as the solid-liquid interface position and shape during vertical Bridgman growth. This sensor methodology is based upon the recognition that in most materials, the ultrasonic velocity (and the elastic stiffness constants that control it) of the solid and liquid phases are temperature dependent and an abrupt increase of the longitudinal wave velocity occurs upon solidification. The laser ultrasonic approach has also been used to measure the ultrasonic velocity of solid and liquid Cd0.96Zn0.04Te as a function of temperature up to 1140°C. Using longitudinal and shear wave velocity values together with data for the temperature dependent density allowed a complete evaluation of the temperature dependent single crystal elastic stiffness constants for solid and the adiabatic bulk modulus for liquid Cd0.96Zn0.04 Te. It was found that the ultrasonic velocities exhibited a strong monotonically decreasing function of temperature in the solid and liquid phases and the longitudinal wave indicated an abrupt almost 50% decrease upon melting. Because ray propagation in partially solidified bodies is complex and defines the sensing methodology, a ray tracing algorithm has been developed to analyze two-dimensional wave propagation in the diametral plane of cylindrical solid-liquid interfaces. Ray path, wavefront and time-of-flight (TOF) projections for rays that travel from a source to an arbitrarily positioned receiver on the diametral plane have been calculated and compared to experimentally measured data on a model liquid-solid interface. The simulations and the experimental results reveal that the interfacial region can be identified from transmission TOF data and when used in conjunction with a nonlinear least squares reconstruction algorithm, the interface geometry (i.e. axial location and shape) can be precisely recovered and the ultrasonic velocities of both solid and liquid phases obtained. To gain insight into the melting and solidification process, a single zone VB growth furnace was integrated with the laser ultrasonic sensor system and used to monitor the melting-solidification and directional solidification characteristics of Cd0.96Zn 0.04Te.

Queheillalt, Douglas Ted

337

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

338

LASER-ULTRASONIC TESTING AND ITS APPLICATIONS TO NUCLEAR REACTOR INTERNALS  

SciTech Connect

A new nondestructive testing technique for surface-breaking microcracks in nuclear reactor components based on laser-ultrasonics is developed. Surface acoustic wave generated by Q-switched Nd:YAG laser and detected by frequency-stabilized long pulse laser coupled with confocal Fabry-Perot interferometer is used to detect and size the cracks. A frequency-domain signal processing is developed to realize accurate sizing capability. The laser-ultrasonic testing allows the detection of surface-breaking microcrack having a depth of less than 0.1 mm, and the measurement of their depth with an accuracy of 0.2 mm when the depth exceeds 0.5 mm including stress corrosion cracking. The laser-ultrasonic testing system combined with laser peening system, which is another laser-based maintenance technology to improve surface stress, for inner surface of small diameter tube is developed. The generation laser in the laser-ultrasonic testing system can be identical to the laser source of the laser peening. As an example operation of the system, the system firstly works as the laser-ultrasonic testing mode and tests the inner surface of the tube. If no cracks are detected, the system then changes its work mode to the laser peening and improves surface stress to prevent crack initiation. The first nuclear industrial application of the laser-ultrasonic testing system combined with the laser peening was completed in Japanese nuclear power plant in December 2004.

Ochiai, M.; Miura, T. [Power and Industrial Sys. R and D Center, Toshiba Corp., 8, Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa 235-8523 (Japan); Yamamoto, S. [Isogo Nuclear Engineering Center, Toshiba Corp., 8, Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa 235-8523 (Japan)

2008-02-28

339

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

340

Size controlled Ag nanoparticles within pores of monolithic mesoporous silica by ultrasonic irradiation  

Microsoft Academic Search

Ag\\/SiO2 monolithic mesoporous nanocomposite was prepared by a simple impregnation of the preformed monolithic porous host in silver nitrate aqueous solution followed by ultrasonic irradiation of the liquid–solid mixture at room temperature. The formation and size of the particle in porous host have been determined from high-resolution transmission electron microscope (HRTEM), UV-Vis absorption band, and transmission electronic microscopy (TEM) analyses.

Wei Chen; Junying Zhang; Yan Di; Zumin Wang; Qi Fang; Weiping Cai

2003-01-01

341

Ultrasound transmission measurements through the os calcis  

Microsoft Academic Search

Summary  A method of measuring ultrasonic propagation in the os calcis was devised for assessing bone properties in humans, Speed-of-sound\\u000a (SOS) and broadband ultrasound attenuation (BUA) were measured using broadband acoustic pulses transmitted and received by\\u000a a pair of focused transducers. The transducers are mounted coaxially in a water tank with the subject's heel in between. Reproducibility\\u000a of results in an

James A. Zagzebski; Phillip J. Rossman; Carmen Mesina; Richard B. Mazess; Ernest L. Madsen

1991-01-01

342

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

343

Lamb Wave Helical Ultrasonic Tomography  

NASA Astrophysics Data System (ADS)

Ultrasonic guided waves have been used for a wide variety of ultrasonic inspection techniques. We describe here a new variation called helical ultrasound tomography (HUT). This new technique, among other things, has direct application to advanced pipe inspection. HUT uses guided ultrasonic waves along with an adaptation of the tomographic reconstruction algorithms developed by seismologists for what they call "cross borehole" tomography. In HUT, the Lamb-like guided waves travel in various helical crisscross paths between two parallel circumferential transducer arrays instead of the planar crisscross seismic paths between two boreholes. Although the measurement itself is fairly complicated, the output of the tomographic reconstruction is a readily interpretable map of a quantity of interest such as pipe wall thickness. We demonstrate the feasibility of the HUT technique via laboratory scans on steel pipe segments into which controlled thinnings have been introduced.

Leonard, K. R.; Hinders, M. K.

2004-02-01

344

Ultrasonic scattering models for cancellous bone  

NASA Astrophysics Data System (ADS)

In recent years, quantitative ultrasound (QUS) measurements have played a growing role in the assessment and management of osteoporosis. This development is attributable to the current wide availability of ultrasonic equipment measuring acoustic parameters in transmission at several skeletal sites. QUS provides equivalent fracture risk assessment compared to conventional x-ray absorptiometric techniques. It is generally accepted that transmission QUS represents a surrogate marker for bone mineral density. Several investigations are currently being conducted to assess innovative QUS techniques to determine and utilize the full potential of this technology for the benefit of detecting pathological conditions that affect bone strength. Among these developments, reflection and scattering techniques may be useful for the quantitative analysis of bone microarchitecture. We will review recent experimental data and theoretical modeling of ultrasound scattering by cancellous bone. Good agreement between experimental data and predictions using a weak scattering model has been reported by different authors for the magnitude and the frequency dependence of the backscatter coefficient. We also found good agreement between the experimental mean trabecular thickness derived from the 3D microarchitecture analysis and theoretical predictions. These results open interesting prospects for bone microarchitecture characterization from in vivo measurements.

Laugier, Pascal; Padilla, Frederic; Jenson, Frederic

2002-05-01

345

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

346

Ultra-short pulse generator  

SciTech Connect

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

347

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

348

Concurrent ultrasonic weld evaluation system  

DOEpatents

A system for concurrent, non-destructive evaluation of partially completed welds for use in conjunction with an automated welder. The system utilizes real time, automated ultrasonic inspection of a welding operation as the welds are being made by providing a transducer which follows a short distance behind the welding head. Reflected ultrasonic signals are analyzed utilizing computer based digital pattern recognition techniques to discriminate between good and flawed welds on a pass by pass basis. The system also distinguishes between types of weld flaws.

Hood, Donald W. (Idaho Falls, ID); Johnson, John A. (Idaho Falls, ID); Smartt, Herschel B. (Idaho Falls, ID)

1987-01-01

349

Concurrent ultrasonic weld evaluation system  

DOEpatents

A system for concurrent, non-destructive evaluation of partially completed welds for use in conjunction with an automated welder is disclosed. The system utilizes real time, automated ultrasonic inspection of a welding operation as the welds are being made by providing a transducer which follows a short distance behind the welding head. Reflected ultrasonic signals are analyzed utilizing computer based digital pattern recognition techniques to discriminate between good and flawed welds on a pass by pass basis. The system also distinguishes between types of weld flaws. 5 figs.

Hood, D.W.; Johnson, J.A.; Smartt, H.B.

1987-12-15

350

Concurrent ultrasonic weld evaluation system  

DOEpatents

A system for concurrent, non-destructive evaluation of partially completed welds for use in conjunction with an automated welder. The system utilizes real time, automated ultrasonic inspection of a welding operation as the welds are being made by providing a transducer which follows a short distance behind the welding head. Reflected ultrasonic signals are analyzed utilizing computer based digital pattern recognition techniques to discriminate between good and flawed welds on a pass by pass basis. The system also distinguishes between types of weld flaws.

Hood, D.W.; Johnson, J.A.; Smartt, H.B.

1985-09-04

351

Elimination of bandwidth effect in attenuation measurement with picosecond ultrasonics  

NASA Astrophysics Data System (ADS)

We study the broadening effect of probing pulse light on the apparent attenuation of the Brillouin oscillation measured with picosecond ultrasonics. We observe experimentally that the attenuation of the Brillouin oscillation is sensitive to the bandwidth, and the apparent attenuation coefficient increases as the bandwidth increases, being far from the intrinsic attenuation coefficient. Theoretical calculation is performed to reconstruct the observed oscillations, and it is confirmed that there are several factors affecting the apparent attenuation in addition to the bandwidth. We finally propose equations that deduce the contribution of the broadening to the apparent attenuation of the Brillouin oscillation.

Maehara, Atsushi; Nakamura, Nobutomo; Ogi, Hirotsugu; Hirao, Masahiko

2014-08-01

352

Biological effects of low-power ultrasonics  

NASA Astrophysics Data System (ADS)

Low-power ultrasonic devices are widely used in non-destructive testing and medical diagnoses. This paper reviews briefly the biological effects related to the mechanical interaction of the ultrasonic beam with human tissues, and the safety approach towards the potential risks involved with the exposure to ultrasound. The potential risks should be considered both regarding the patients treated or diagnosed by ultrasonics, and the personnel operating routinely medical ultrasonic systems and NDE ultrasonic equipment. The paper also points out a few issues related to the safe use of ultrasound, that seem to be worth of further research or consideration.

Buhbinder, R.; Dickstein, P. A.

2002-05-01

353

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

354

Steel castings Ultrasonic examination, Part 2: Steel castings for highly stressed components  

E-print Network

This European Standard specifies the requirements for the ultrasonic examination of steel castings (with ferritic structure) for highly stressed components and the methods for determining internal discontinuities by the pulse echo technique. This European Standard applies to the ultrasonic examination of steel castings which have usually received a grain refining heat treatment and which have wall thicknesses up to and including 600 mm. For greater wall thicknesses, special agreements apply with respect to test procedure and recording levels. This European Standard does not apply to austenitic steels and joint welds.

International Organization for Standardization. Geneva

2004-01-01

355

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

356

Ultrasonic Band Gaps in Periodic Stack of Plates - Simulation and Experiments  

SciTech Connect

Ultrasonic band gaps were simulated using various numerical techniques for 1-D periodic structures. The pulse propagation characteristics were simulated using transient finite element analysis. The frequency domain characteristics were simulated using forced periodic response analysis, Thompson Haskell transfer matrix and acoustic impedance based calculations. Dispersion curves were also obtained using eigen value lattice simulations. Simulation of the band gaps obtained using these numerical methods agreed well with each other. Experiments were carried out on layered material (aluminum-plexiglas) at ultrasonic frequencies. The measured band gaps matched with the simulation results. Numerical and experimental results are also presented for mirror symmetric periodic stacks.

Ram, B. C.; Padma, Kumar P.; Krishnamurthy, C. V.; Balasubramaniam, Krishnan [Center for Non Destructive Evaluation, IIT Madras-Chennai 600036 (India)

2006-03-06

357

Piezoelectric thick film ultrasonic transducers fabricated by a sol-gel spray technique.  

PubMed

Thick film broadband ultrasonic transducers (UTs) produced by a sol-gel spray technique and operated below 10 MHz are presented. These UTs are formed by dispersing PZT and LiTaO3 particles, respectively in Al2O3 and PZT sol-gel solution. The 50-100 microm thick films have been deposited on curved steel, flat steel and aluminum substrates and steel rods. Ultrasonic pulse-echo signals with a signal to noise ratio of more than 25 dB are experimentally obtained for the operating temperatures up to 250 degrees C. PMID:12479598

Kobayashi, M; Olding, T R; Sayer, M; Jen, C K

2002-10-01

358

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 strength in graphite/epoxy composites.

Prosser, William H.; Green, Robert E., Jr.

1987-01-01

359

Ultrasonic Thermometry for In-Pile Temperature Detection  

SciTech Connect

The Idaho National Laboratory has recently initiated a new effort to evaluate the viability of using ultrasonic thermometry technology as an improved sensor for detecting temperature during irradiation testing. Ultrasonic thermometers (UTs) work on the principle that the speed at which sound travels through a material (acoustic velocity) is dependant on the temperature of the material. By introducing an acoustic pulse to the sensor and measuring the time delay of echoes, temperature may be derived. UTs have several advantages over other sensor types. UTs can be made very small, as the sensor consists only of a small diameter rod which may or may not require a sheath. Measurements may be made near the melting point of the sensor material, as no electrical insulation is required; and shunting effects are avoided. Most attractive, however, is the ability to introduce acoustic discontinuities to the sensor, as this enables temperature measurements at several points along the sensor length (allowing temperature profiling with a single sensor). A typical multi-sensor UT system, with key components identified, is shown in Figure 1. As indicated in this figure, a narrow ultrasonic pulse is generated in a magnetostrictive rod by an excitation coil. The ultrasonic pulse propagates to the sensor wire, where a fraction of the pulse energy is reflected at each discontinuity (notches or diameter change). Each reflected pulse is received by the excitation coil, transformed into an electrical signal, amplified and evaluated in a start/stop counter system. The time interval between two adjacent echoes is evaluated and compared to a calibration curve to give the average temperature in the corresponding sensor segment. When a number of notches are available on the wire sensor, the various measurements give access to a temperature profile along the probe. UTs have been used successfully for several applications; however, several problems have limited the success of these sensors. For example, signal processing can be very complicated, as multiple echoes may overlap. Contact between the sensor and solid materials can cause extraneous echoes. If a sheath is required, contact bonding at high temperatures may cause extraneous echoes or attenuation of primary echoes. The most successful materials used in previous studies, tungsten and rhenium, are unattractive for nuclear applications due to material transmutation. Clearly, in order for ultrasonic thermometers to be viable for an in-pile sensor, these issues must be resolved through the use of modern signal processing and materials technologies. As part of the INL feasibility study, all of the issues associated with UT use and proposed resolution options will be identified and evaluated. Once most promising options are proven, it is planned to produce one or more prototype ultrasonic temperature sensors for evaluation. Ultimately, a full test should include a long term installation in a high temperature test assembly installed in a high neutron flux environment, such as that found in the Idaho National Laboratory’s Advanced Test Reactor.

J.E. Daw; J.L. Rempe; S.C. Wilkins

2002-11-01

360

Dental hard tissue characterization using laser-based ultrasonics  

NASA Astrophysics Data System (ADS)

Dental health care and research workers require a means of imaging the structures within teeth in vivo. One critical need is the detection of tooth decay in its early stages. If decay can be detected early enough, the process can be monitored and interventional procedures, such as fluoride washes and controlled diet, can be initiated to help re-mineralize the tooth. Currently employed x-ray imaging is limited in its ability to visualize interfaces and incapable of detecting decay at a stage early enough to avoid invasive cavity preparation followed by a restoration. To this end, non-destructive and non-contact in vitro measurements on extracted human molars using laser-based ultrasonics are presented. Broadband ultrasonic waves are excited in the extracted sections by using a pulsed carbon-dioxide (CO2) laser operating in a region of high optical absorption in the dental hard tissues. Optical interferometric detection of the ultrasonic wave surface displacements in accomplished with a path-stabilized Michelson-type interferometer. Results for bulk and surface in-vitro characterization of caries are presented on extracted molars with pre-existing caries.

Blodgett, David W.; Massey, Ward L.

2003-07-01

361

Imaging Laser Ultrasonics Measurement of the Elastodynamic Properties of Paper  

SciTech Connect

Many sheet and plate material industries (e.g. paper) desire knowledge of the anisotropic stiffness properties of their material to optimize the manufacturing process. A determination of the anisotropic elastic matrix would be very beneficial for determination of parameters, such as as microstructural texture, fiber or grain orientation and stiffness. The propagation of ultrasonic waves in plates is a method for determining the anisotropic elastic properties in a nondestructive manner. Laser ultrasonics offes a noncontacting means to implement these measurements in the workplace by employing pulsed or modulated light to excite symmetric and antisymmetric plate waves concurrent with optical interferometric detection. Measurements can then be performed along the machine and cross directions to obtain parameters that are used empirically for process monitoring. Recently, the INEEL has developed a full-field view laser based ultrasonic imaging method that allows simultaneous measurement of plate wave motion in all planar directions within a single image without scanning. The imaging measurements are based on dynamic holography using photorefractive materials for interferometric deteciton and are operated as normal video rates. Results from this laser based imaging approach are presented that record Lamb wave mode wavefronts in all planar directions from localized sources in a single image. Specific numerical predictions for flexural wave propagation in distinctly different types of paper accounting fully for orthotropic anisotropy are presented and compared with direct imaging measurements. Very good agreement with theoretical calculations is obtained for the lowest antisymmetric plate mode in all planar directions using paper properties independently determined by others.

Telschow, Kenneth Louis; Deason, Vance Albert

2001-10-01

362

The Application of Ultrasonic Inspection to Crimped Electrical Connections  

NASA Technical Reports Server (NTRS)

The development of a new ultrasonic measurement technique to quantitatively assess wire crimp terminations is discussed. The development of a prototype instrument, based on a modified, commercially available, crimp tool, is demonstrated for applying this technique when wire crimps are installed. The crimp tool has three separate crimping locations that accommodate the three different ferrule diameters. The crimp tool in this study is capable of crimping wire diameters ranging from 12 to 26 American Wire Gauge (AWG). A transducer design is presented that allows for interrogation of each of the three crimp locations on the crimp tool without reconfiguring the device. An analysis methodology, based on transmitted ultrasonic energy and timing of the first received pulse is shown to correlate to both crimp location in the tool and the AWG of the crimp/ferrule combination. The detectability of a number of the crimp failure pathologies, such as missing strands, partially inserted wires and incomplete crimp compression, is discussed. A wave propagation model, solved by finite element analysis, describes the compressional ultrasonic wave propagation through the junction during the crimping process.

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

2010-01-01

363

Pulse transformer R and D for NLC klystron pulse modulator  

SciTech Connect

The authors have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and requires a larger core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and a pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests using a klystron load are also presented.

Akemoto, M.; Gold, S.; Krasnykh, A.; Koontz, R.

1997-07-01

364

Development of the pulse transformer for NLC klystron pulse modulator  

SciTech Connect

We have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests are also presented.

Akemoto, M.; Gold, S.; Koontz, R.; Krasnykh, A.

1997-05-01

365

Medical Ultrasonic Imaging Problem Presenter  

E-print Network

in the PZT to the lower value in the tissue in order to improve imaging. Though the media in the matchingMedical Ultrasonic Imaging Problem Presenter Bruno Haider GE Global Research Center Problem ultrasound devices are used extensively to "see" soft tissue structures inside the body. High

Edwards, David A.

366

Flexible ultrasonic pipe inspection apparatus  

DOEpatents

Pipe crawlers, pipe inspection {open_quotes}rabbits{close_quotes} and similar vehicles are widely used for inspecting the interior surfaces of piping systems, storage tanks and process vessels for damaged or flawed structural features. This paper describes the design of a flexible, modular ultrasonic pipe inspection apparatus.

Jenkins, C.F.; Howard, B.D.

1994-01-01

367

Ultrasonic seam welding. Final report  

SciTech Connect

Ultrasonic seam welding has been evaluated for making continuous seam welds on aluminum and copper-foil conductors. A seam welding system has been designed and fabricated, weldable material combinations have been identified, and the process parameters for welding materials applicable to flat cable production have been established.

Darner, G.S.

1980-06-01

368

Ultrasonic Levitation for Liquid Droplet  

Microsoft Academic Search

Ultrasonic levitation in a gravity field was tested using a viscous liquid at a frequency range from 20 kHz to 28 kHz. Red ink and glycerin droplets havingdiameters in the range of 3 mm to 5 mm were placed at a node of a standing wave. As a result, the droplets were not only flattened like a disk, but also

Tetsuro Otsuka; Tomoo Nakane

2002-01-01

369

Transmission eigenvalues  

NASA Astrophysics Data System (ADS)

In inverse scattering theory, transmission eigenvalues can be seen as the extension of the notion of resonant frequencies for impenetrable objects to the case of penetrable dielectrics. The transmission eigenvalue problem is a relatively late arrival to the spectral theory of partial differential equations. Its first appearance was in 1986 in a paper by Kirsch who was investigating the denseness of far-field patterns for scattering solutions of the Helmholtz equation or, in more modern terminology, the injectivity of the far-field operator [1]. The paper of Kirsch was soon followed by a more systematic study by Colton and Monk in the context of developing the dual space method for solving the inverse scattering problem for acoustic waves in an inhomogeneous medium [2]. In this paper they showed that for a spherically stratified media transmission eigenvalues existed and formed a discrete set. Numerical examples were also given showing that in principle transmission eigenvalues could be determined from the far-field data. This first period of interest in transmission eigenvalues was concluded with papers by Colton et al in 1989 [3] and Rynne and Sleeman in 1991 [4] showing that for an inhomogeneous medium (not necessarily spherically stratified) transmission eigenvalues, if they existed, formed a discrete set. For the next seventeen years transmission eigenvalues were ignored. This was mainly due to the fact that, with the introduction of various sampling methods to determine the shape of an inhomogeneous medium from far-field data, transmission eigenvalues were something to be avoided and hence the fact that transmission eigenvalues formed at most a discrete set was deemed to be sufficient. In addition, questions related to the existence of transmission eigenvalues or the structure of associated eigenvectors were recognized as being particularly difficult due to the nonlinearity of the eigenvalue problem and the special structure of the associated transmission eigenvalue problem. The need to answer these questions became important after a series of papers by Cakoni et al [5], and Cakoni et al [6] suggesting that these transmission eigenvalues could be used to obtain qualitative information about the material properties of the scattering object from far-field data. The first answer to the existence of transmission eigenvalues in the general case was given in 2008 when Päivärinta and Sylvester showed the existence of transmission eigenvalues for the index of refraction sufficiently large [7] followed in 2010 by the paper of Cakoni et al who removed the size restriction on the index of refraction [8]. More importantly, in the latter it was shown that transmission eigenvalues yielded qualitative information on the material properties of the scattering object and Cakoni et al established in [9] that transmission eigenvalues could be determined from the Tikhonov regularized solution of the far-field equation. Since the appearance of these papers there has been an explosion of interest in the transmission eigenvalue problem (we refer the reader to our recent survey paper [10] for a detailed account of the developments in this field up to 2012) and the papers in this special issue are representative of the myriad directions that this research has taken. Indeed, we are happy to see that many open theoretical and numerical questions raised in [10] have been answered (totally or partially) in the contributions of this special issue: the existence of transmission eigenvalues with minimal assumptions on the contrast, the numerical evaluation of transmission eigenvalues, the inverse spectral problem, applications to non-destructive testing, etc. In addition to these topics, many other new investigations and research directions have been proposed as we shall see in the brief content summary below. A number of papers in this special issue are concerned with the question of existence of transmission eigenvalues and the structure of the associated transmission eigenfunctions. The three papers by respectively Robbiano [11], Blasten and P

Cakoni, Fioralba; Haddar, Houssem

2013-10-01

370

Ultrasonic guided wave monitoring of composite wing skin-to-spar bonded joints in aerospace structures  

NASA Astrophysics Data System (ADS)

The monitoring of adhesively bonded joints by ultrasonic guided waves is the general topic of this paper. Specifically, composite-to-composite joints representative of the wing skin-to-spar bonds of unmanned aerial vehicles (UAVs) are examined. This research is the first step towards the development of an on-board structural health monitoring system for UAV wings based on integrated ultrasonic sensors. The study investigates two different lay-ups for the wing skin and two different types of bond defects, namely poorly cured adhesive and disbonded interfaces. The assessment of bond state is based on monitoring the strength of transmission through the joints of selected guided modes. The wave propagation problem is studied numerically by a semi-analytical finite element method that accounts for viscoelastic damping, and experimentally by ultrasonic testing that uses small PZT disks preferably exciting and detecting the single-plate s0 mode. Both the models and the experiments confirm that the ultrasonic energy transmission through the joint is highly dependent on the bond conditions, with defected bonds resulting in increased transmission strength. Large sensitivity to the bond conditions is found at mode coupling points, as a result of the large interlayer energy transfer.

Matt, Howard; Bartoli, Ivan; Lanza di Scalea, Francesco

2005-10-01

371

An ultrasonic phased array system for NDT of steel structures  

Microsoft Academic Search

A phased array ultrasonic inspection system is being developed ot obtain electronically scanned ultrasonic images of the inside of steel structures for nondestructive evaluation. This phased array ultrasonic inspection system is made up of computer, scanner, motion controller, motor driver, ultrasonic emission, receiving & delay circuit, high speed data acquisition circuit and ultrasonic phased array transducer, this system has the

Baohua Shan; Jinping Ou

2005-01-01

372

Tunable ultrasonic phononic crystal controlled by infrared radiation  

NASA Astrophysics Data System (ADS)

A tunable phononic crystal based ultrasonic filter was designed by stimulating the phase of the polymeric material embedded in a periodic structure using infrared radiation. The acoustic filter can be tuned remotely using thermal stimulation induced by the infrared radiation. The filter is composed of steel cylinder scatterers arranged periodically in a background of bulk poly (N-isopropylacrylamide) polymer hydrogel. The lattice structure creates forbidden bands for certain sets of mechanical waves that cause it to behave as an ultrasonic filter. Since the bandstructure is determined by not only the arrangement of the scatterers but also the physical properties of the materials composing the scatterers and background, modulating either the arrangement or physical properties will alter the effect of the crystal on propagating mechanical waves. Here, the physical properties of the filter are varied by inducing changes in the polymer hydrogel using an electromagnetic thermal stimulus. With particular focus on the k00-wave, the transmission of ultrasonic wave changes by as much as 20 dBm, and band widths by 22% for select bands.

Walker, Ezekiel; Reyes, Delfino; Rojas, Miguel Mayorga; Krokhin, Arkadii; Wang, Zhiming; Neogi, Arup

2014-10-01

373

Fatigue Crack Measurement in Composite Materials by Ultrasonic Methods  

NASA Technical Reports Server (NTRS)

The nondestructive detection of intra-ply microcracking in unlined pressure vessels fabricated from composite materials is critical to ensuring mission success. Microcracking in composite structures due to combined fatigue and cryogenic thermal loading can be very troublesome to detect in-service and when it begins to link through the thickness can cause leakage and failure of the structure. These leaks may lead to loss of pressure/propellant, increased risk of explosion and possible cryo-pumping. The work presented herein develops a method and an instrument to locate and measure intraply fatigue cracking through the thickness of laminated composite material by means of correlation with ultrasonic resonance. Resonant ultrasound spectroscopy provides measurements which are, sensitive to both the microscopic and macroscopic properties of an object. Elastic moduli, acoustic attenuation, and geometry can all be probed. The approach is based on the premise of half-wavelength resonance. The method injects a broadband ultrasonic wave into the test structure using a swept frequency technique. This method provides dramatically increased energy input into the test article, as compared to conventional spike pulsed ultrasonics. This relative energy increase improves the ability to measure finer details in the materials character, such as micro-cracking and porosity. As the micro-crack density increases, more interactions occur with the higher frequency (small wavelength) components of the signal train causing the spectrum to shift toward lower frequencies. Preliminary experiments have verified a measurable effect on the resonance spectrum of the ultrasonic data to detect microcracking. Methods involving self organizing neural networks and other clustering algorithms show that the resonance ultrasound signatures from composites vary with the degree of microcracking and can be separated and identified.

Walker, James L.; Russell, Samuel S.; Suits, Michael W.; Workman, Gary L.; Watson, Jason M.; Thom, Robert (Technical Monitor)

2002-01-01

374

Ultrasonic measurements of Young's modulus and extensional wave attenuation in refractory metal wires at elevated temperatures with application to ultrasonic thermometry  

Microsoft Academic Search

Ultrasonic velocity and attenuation measurements have been made by traveling-wave methods on several refractory metals and their alloys. Broad-band pulses centered around 120 kHz were used for extensional waves (and some torsional waves) in wire specimens. Elastic moduli calculated from the velocities decrease with increasing temperature; the slope increases in magnitude at about half the absolute melting point. At the

E. P. Papadakis; K. A. Fowler; L. C. Lynnworth; A. Robertson; E. D. Zysk

1974-01-01

375

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

376

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

377

Determination of Residual Stress in Composite Materials Using Ultrasonic Waves  

NASA Technical Reports Server (NTRS)

The performance of high temperature composites can be significantly affected by the presence of residual stresses. These stresses arise during cooling processes from fabrication to room temperature due to mismatch of thermal expansion coefficients between matrix and fiber materials. This effect is especially pronounced in metal matrix and intermetallic composites. It can lead to plastic deformations, matrix cracking and fiber/matrix interface debonding. In this work the feasibility of ultrasonic techniques for residual stress assessment in composites is addressed. A novel technique for absolute stress determination in orthotropic materials from angular dependencies of ultrasonic velocities is described. The technique is applicable for determination of both applied and residual stresses and does not require calibration measurements on a reference sample. The important advantage of this method is that stress is determined simultaneously with stress-dependent elastic constants and is thus decoupled from the material texture. It is demonstrated that when the principal plane stress directions coincide with acoustical axes, the angular velocity data in the plane perpendicular to the stress plane may be used to determine both stress components. When the stress is off the acoustical axes, the shear and the difference of the normal stress components may be determined from the angular dependence of group velocities in the plane of stresses. Synthetic sets of experimental data corresponding to materials with different anisotropy and stress levels are used to check the applicability of the technique. The method is also verified experimentally. A high precision ultrasonic wave transmission technique is developed to measure angular dependence of ultrasonic velocities. Examples of stress determination from experimental velocity data are given. A method is presented for determination of velocities of ultrasonic waves propagating through the composite material with residual stresses. It is based on the generalized self-consistent multiple scattering model. Calculation results for longitudinal and shear ultrasonic wave velocities propagating perpendicular to the fibers direction in SCS-6/Ti composite with and without residual stresses are presented. They show that velocity changes due to presence of stresses are of order 1%.

Rokhlin, S. I.

1997-01-01

378

Transmission communication  

E-print Network

communication system . MODEM functions . Channel has finite bandwidth and introduces noise: two main factors communication, this lecture we will again go through pulse shaping and Tx/Rx filter pair, but in more depth

Chen, Sheng

379

Effect of ultrasonic irradiation on mammalian cells and chromosomes in vitro  

NASA Technical Reports Server (NTRS)

Human peripheral blood and HeLa cells were irradiated in vitro at the ultrasonic frequency of 65 kHz. The whole blood and HeLa cell suspensions were exposed to continuous and pulsed ultrasonic power levels of 0.12, 0.16, 0.72, 1.12 and 2.24 W for a period of one minute. The method of ultrasonic irradiation was carried out with the whole blood or HeLa cell suspensions coupled directly to a cylindrical transducer while heating of the cell suspensions in excess of 41 C was avoided. Irradiated and unirradiated peripheral blood lymphocyte chromosome cultures were prepared and scored for selected numerical and morphological aberrations. There was no significant difference in the frequency of chromosomal aberrations between irradiated and unirradiated cells.

Roseboro, J. A.; Buchanan, P.; Norman, A.; Stern, R.

1978-01-01

380

Time reducing process for biofuel production from non edible oil assisted by ultrasonication.  

PubMed

Limited resources of conventional fuels such as petrodiesel have led to the search for alternative fuels. Various convention batch/continuous processes for the biodiesel production have been developed before the recent year. All processes are time consuming with high labor cost. Thus, we need a new process for biodiesel production which reduces the reaction time and production cost as well as save the energy. In this work, ultrasonic assisted transesterification of Jatrophacurcas oil is carried out in the presence of methanol and potassium hydroxide (KOH) as catalyst, keeping the molar ratio of oil to alcohol 1:5, catalyst concentration 0.75 wt% of oil, ultrasonic amplitude 50% and pulse 0.3 cycle, 7 min reaction time under atmospheric condition. Ultrasonic mixing has increased the rate of transesterification reaction as compare to the mechanical mixing. PMID:24792785

Kumar, Gajendra; Kumar, Dharmendra; Johari, Rajeev

2014-09-01

381

Non-Destructive Evaluation of Depth of Surface Cracks Using Ultrasonic Frequency Analysis  

PubMed Central

Ultrasonic is one of the most common uses of a non-destructive evaluation method for crack detection and characterization. The effectiveness of the acoustic-ultrasound Structural Health Monitoring (SHM) technique for the determination of the depth of the surface crack was presented. A method for ultrasonic sizing of surface cracks combined with the time domain and frequency spectrum was adopted. The ultrasonic frequency spectrum was obtained by Fourier transform technique. A series of test specimens with various depths of surface crack ranging from 1 mm to 8 mm was fabricated. The depth of the surface crack was evaluated using the pulse-echo technique. In this work, three different longitudinal waves with frequencies of 2.25 MHz, 5 MHz and 10 MHz were employed to investigate the effect of frequency on the sizing detection of surface cracks. Reasonable accuracies were achieved with measurement errors less than 7%. PMID:25225875

Her, Shiuh-Chuan; Lin, Sheng-Tung

2014-01-01

382

A Portable Ultrasonic Nondestructive Inspection System for Metal Matrix Composite Track Shoes  

NASA Astrophysics Data System (ADS)

Cast aluminum track shoes reinforced with metal matrix composite (MMC) inserts at heavy loading areas such as center splines and sprocket windows are light in weight, and can resist high temperature and wear. Various defects such as disbonds at the insert-substrate interface, cracks and porosity in the MMC layer, etc. can be introduced during the manufacturing process and/or in service. This paper presents a portable ultrasonic system to automatically inspect tank track shoes for disbond. Ultrasonic pulse/echo inspection has shown good reliability for disbond detection. A prototype sensor array fixture has been designed and fabricated to prove the feasibility. Good agreements between the sensor fixture results and ultrasonic C-scan images were obtained.

Mi, Bao; Zhao, Xiaoliang; Qian, Tao; Stevenson, Mark; Kwan, Chiman; Owens, Steven E.; Royer, Roger L.; Tittmann, Bernhard R.; Raju, Basavaraju B.

2007-03-01

383

Ultrasonic preliminary measurements of oenological malolactic fermentation parameters in red wine  

NASA Astrophysics Data System (ADS)

In the winemaking process, the malolactic fermentation is an essential process in the production of high quality red wines which concerns the conversion of malate into lactate. In this work, the ultrasonic velocity through wine samples with different concentrations of malate and lactate was measured using the pulse echo technique with 1 MHz tone burst signals. The evolution of these concentrations during malolactic fermentation was taken into account in order to determine the ratio between concentrations of malate and lactate of the different samples. These preliminary results have revealed that the ultrasonic velocity increases during the conversion of malate to lactate. In addition, measurements have been conducted to quantify the influence of variations in turbidity and temperature on test samples. Therefore, these results show the possibility of using ultrasonic velocity measurements for on-line monitoring the malolactic fermentation of red wine and may help to improve and contribute to the development of the winemaking process.

Novoa-Díaz, D. F.; Puig-Pujol, A.; García-Álvarez, J.; Chávez, J. A.; Turó, A.; Mínguez, S.; García-Hernández, M. J.; Bertran, E.; Salazar, J.

2012-12-01

384

Femtosecond nonlinear ultrasonics in gold probed with ultrashort surface plasmons.  

PubMed

Fundamental interactions induced by lattice vibrations on ultrafast time scales have become increasingly important for modern nanoscience and technology. Experimental access to the physical properties of acoustic phonons in the terahertz-frequency range and over the entire Brillouin zone is crucial for understanding electric and thermal transport in solids and their compounds. Here we report on the generation and nonlinear propagation of giant (1 per cent) acoustic strain pulses in hybrid gold/cobalt bilayer structures probed with ultrafast surface plasmon interferometry. This new technique allows for unambiguous characterization of arbitrary ultrafast acoustic transients. The giant acoustic pulses experience substantial nonlinear reshaping after a propagation distance of only 100?nm in a crystalline gold layer. Excellent agreement with the Korteveg-de Vries model points to future quantitative nonlinear femtosecond terahertz-ultrasonics at the nano-scale in metals at room temperature. PMID:23403569

Temnov, Vasily V; Klieber, Christoph; Nelson, Keith A; Thomay, Tim; Knittel, Vanessa; Leitenstorfer, Alfred; Makarov, Denys; Albrecht, Manfred; Bratschitsch, Rudolf

2013-01-01

385

Pulse power linac  

DOEpatents

A linear acceleration for charged particles is constructed of a plurality of transmission line sections that extend between a power injection region and an accelerating region. Each line section is constructed of spaced plate-like conductors and is coupled to an accelerating gap located at the accelerating region. Each gap is formed between a pair of apertured electrodes, with all of the electrode apertures being aligned along a particle accelerating path. The accelerating gaps are arranged in series, and at the injection region the line sections are connected in parallel. At the injection region a power pulse is applied simultaneously to all line sections. The line sections are graduated in length so that the pulse reaches the gaps in a coordinated sequence whereby pulse energy is applied to particles as they reach each of the gaps along the accelerating path.

Villa, Francesco (Alameda, CA)

1990-01-01

386

Mechanistic modeling of destratification in cryogenic storage tanks using ultrasonics.  

PubMed

Stratification is one of the main causes for vaporization of cryogens and increase of tank pressure during cryogenic storage. This leads subsequent problems such as cavitation in cryo-pumps, reduced length of storage time. Hence, it is vital to prevent stratification to improve the cost efficiency of storage systems. If stratified layers exist inside the tank, they have to be removed by suitable methods without venting the vapor. Sonication is one such method capable of keeping fluid layers mixed. In the present work, a mechanistic model for ultrasonic destratification is proposed and validated with destratification experiments done in water. Then, the same model is used to predict the destratification characteristics of cryogenic liquids such as liquid nitrogen (LN?), liquid hydrogen (LH?) and liquid ammonia (LNH?). The destratification parameters are analysed for different frequencies of ultrasound and storage pressures by considering continuous and pulsed modes of ultrasonic operation. From the results, it is determined that use of high frequency ultrasound (low-power/continuous; high-power/pulsing) or low frequency ultrasound (continuous operation with moderate power) can both be effective in removing stratification. PMID:23810463

Jagannathan, T K; Mohanan, Srijith; Nagarajan, R

2014-01-01

387

Effect of Ultrasonic Frequency on Lactic Acid Fermentation Promotion by Ultrasonic Irradiation  

NASA Astrophysics Data System (ADS)

The authors have been researching the promotion of lactic acid fermentation by ultrasonic irradiation. In the past research, it was proven that ultrasonic irradiation is effective in the process of fermentation, and the production of yoghurt and kefir was promoted. In this study, the effect of the ultrasonic frequency in this fermentation process was examined. In the frequency range of this study, it was found that the action of fermentation promotion was exponentially proportionate to the irradiated ultrasonic frequency.

Shimada, Tadayuki; Ohdaira, Etsuzo; Masuzawa, Nobuyoshi

2004-05-01

388

Force transmissibility versus displacement transmissibility  

NASA Astrophysics Data System (ADS)

It is well-known that when a single-degree-of-freedom (sdof) system is excited by a continuous motion of the foundation, the force transmissibility, relating the force transmitted to the foundation to the applied force, equals the displacement transmissibility. Recent developments in the generalization of the transmissibility to multiple-degree-of-freedom (mdof) systems have shown that similar simple and direct relations between both types of transmissibility do not appear naturally from the definitions, as happens in the sdof case. In this paper, the authors present their studies on the conditions under which it is possible to establish a relation between force transmissibility and displacement transmissibility for mdof systems. As far as the authors are aware, such a relation is not currently found in the literature, which is justified by being based on recent developments in the transmissibility concept for mdof systems. Indeed, it does not appear naturally, but the authors observed that the needed link is present when the displacement transmissibility is obtained between the same coordinates where the applied and reaction forces are considered in the force transmissibility case; this implies that the boundary conditions are not exactly the same and instead follow some rules. This work presents a formal derivation of the explicit relation between the force and displacement transmissibilities for mdof systems, and discusses its potential and limitations. The authors show that it is possible to obtain the displacement transmissibility from measured forces, and the force transmissibility from measured displacements, opening new perspectives, for example, in the identification of applied or transmitted forces. With this novel relation, it becomes possible, for example, to estimate the force transmissibility matrix with the structure off its supports, in free boundary conditions, and without measuring the forces. As far as force identification is concerned, this novel approach significantly decreases the computational effort when compared to conventional approaches, as it requires only local information of the sets of coordinates involved. Numerical simulations and experimental examples are presented and discussed, to illustrate the proposed developments.

Lage, Y. E.; Neves, M. M.; Maia, N. M. M.; Tcherniak, D.

2014-10-01

389

Unified Ultrasonic/Eddy-Current Data Acquisition  

NASA Technical Reports Server (NTRS)

Imaging station for detecting cracks and flaws in solid materials developed combining both ultrasonic C-scan and eddy-current imaging. Incorporation of both techniques into one system eliminates duplication of computers and of mechanical scanners; unifies acquisition, processing, and storage of data; reduces setup time for repetitious ultrasonic and eddy-current scans; and increases efficiency of system. Same mechanical scanner used to maneuver either ultrasonic or eddy-current probe over specimen and acquire point-by-point data. For ultrasonic scanning, probe linked to ultrasonic pulser/receiver circuit card, while, for eddy-current imaging, probe linked to impedance-analyzer circuit card. Both ultrasonic and eddy-current imaging subsystems share same desktop-computer controller, containing dedicated plug-in circuit boards for each.

Chern, E. James; Butler, David W.

1993-01-01

390

Transmission Communication  

E-print Network

ELEC3028 Digital Transmission -- MODEM S Chen Digital Communication System . Purpose: communicate Communication System (continue) . A pair of transmitter (coder, modulator) and receiver (demodulator, decoder) is called transceiver . Information theory provides us basic communication theory for communication system

Chen, Sheng

391

Ultrasonic attenuation in pearlitic steel.  

PubMed

Expressions for the attenuation coefficients of longitudinal and transverse ultrasonic waves are developed for steel with pearlitic microstructure. This type of lamellar duplex microstructure influences attenuation because of the lamellar spacing. In addition, longitudinal attenuation measurements were conducted using an unfocused transducer with 10 MHz central frequency on the cross section of a quenched railroad wheel sample. The dependence of longitudinal attenuation on the pearlite microstructure is observed from the changes of longitudinal attenuation from the quenched tread surface to deeper locations. The results show that the attenuation value is lowest and relatively constant within the quench depth, then increases linearly. The experimental results demonstrate a reasonable agreement with results from the theoretical model. Ultrasonic attenuation provides an important non-destructive method to evaluate duplex microstructure within grains which can be implemented for quality control in conjunction with other manufacturing processes. PMID:24268679

Du, Hualong; Turner, Joseph A

2014-03-01

392

Discriminating ultrasonic proximity detection system  

DOEpatents

This invention uses an ultrasonic transmitter and receiver and a microprocessor to detect the presence of an object. In the reset mode the invention uses a plurality of echoes from each ultrasonic burst to create a reference table of the echo-burst-signature of the empty monitored environment. The invention then processes the reference table so that it only uses the most reliable data. In the detection mode the invention compares the echo-burst-signature of the present environment with the reference table, detecting an object if there is a consistent difference between the echo-burst-signature of the empty monitored environment recorded in the reference table and the echo-burst-signature of the present environment.

Annala, Wayne C. (Durango, CO)

1989-01-01

393

Ultrasonic disruption of algae cells  

NASA Astrophysics Data System (ADS)

During last decade there has been increasing interest in the production of sustainable fuels from microalgae (R.H. Wijffels and M.J. Barbosa, 2010; Singh et al 2011; D.H. Lee 2011). The aim of this project was to determine if algal cells can be ultrasonically disrupted to release lipids for biofuel production. Ultrasonic disruption of two unicellular algal species: Dunnaliella salina and Nannochloropsis oculata was investigated using a 20 kHz probe. Haemocytometer, optical density, UV-Vis, fluoro-spectrophotometer and confocal microscopy results demonstrated complete cell destruction of Dunaliella salina within 16 minutes of sonication. Results obtained for Nannochloropsis oculata differed in that ultrasound dispersed clumped cells with little or no cell disruption, as observed by haemocytometer and confocal microscopy analysis. However, UV-Visible and fluoro-spectrophotometer analysis indicated chlorophyll release following sonication, suggesting some cell disruption had occurred.

King, P. M.; Nowotarski, K.; Joyce, E. M.; Mason, T. J.

2012-05-01

394

Ultrasonic enhancement of battery diffusion.  

PubMed

It has been demonstrated that sonic energy can be harnessed to enhance convection in Galvanic cells during cyclic voltammetry; however, the practical value of this approach is limited due to the lack of open volumes for convection patterns to develop in most batteries. This study evaluates the ability of ultrasonic waves to enhance diffusion in membrane separators commonly used in sandwich-architecture batteries. Studies include the measuring of open-circuit performance curves to interpret performances in terms of reductions in concentration overpotentials. The use of a 40 kHz sonicator bath can consistently increase the voltage of the battery and reduce overpotential losses up to 30%. This work demonstrates and quantifies battery enhancement due to enhanced diffusion made possible with ultrasonic energy. PMID:24210813

Hilton, R; Dornbusch, D; Branson, K; Tekeei, A; Suppes, G J

2014-03-01

395

Eggshell Cutter Using Ultrasonic Vibration  

NASA Astrophysics Data System (ADS)

An eggshell cutting apparatus which utilizes ultrasonic vibration was developed, replacing the conventional apparatus which uses an air cutter, to cut eggshells at the blunt end of eggs. Two ultrasonic vibration sources were used: one with longitudinal vibration only and the other with torsional vibration plus longitudinal vibration. Eggshell cutting experiments using these vibration sources were conducted. The eggshell cutting time sharply decreased with increasing longitudinal vibration amplitude as well as increasing input power. When the source with torsional vibration plus longitudinal vibration was used and the amplitude of longitudinal vibration was 12 ?m or less, the torsional vibration was effective for cutting eggshells. Furthermore, at the same input power, the eggshell cutting time by the source with longitudinal vibration only was shorter than that by the source with torsional vibration plus longitudinal vibration. When an egg was cut using the apparatus, there was essentially no cutting noise and the cut surface was smooth.

Miura, Hikaru

2003-05-01

396

Ultrasonic material hardness depth measurement  

DOEpatents

The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part. 12 figs.

Good, M.S.; Schuster, G.J.; Skorpik, J.R.

1997-07-08

397

The upcoming revolution in ultrasonic guided waves  

NASA Astrophysics Data System (ADS)

This paper will include discussions on fundamental principles and market forces associated with the upcoming revolution in ultrasonic guided waves. A literature survey is also outlined covering some selected major developments this past decade. A few applications in pipe, rail, bonding and composites, imaging and tomography, ultrasonic vibration, de-icing, structural health monitoring, gas entrapment, and non-linear methods are treated to provide an idea of where we are heading with ultrasonic guided waves.

Rose, Joseph L.

2011-04-01

398

Advanced Ultrasonic Measurement Methodology for Non-Invasive Interrogation and Identification of Fluids in Sealed Containers  

SciTech Connect

The Hazardous Materials Response Unit (HMRU) and the Counterterrorism and Forensic Science Research Unit (CTFSRU), Laboratory Division, Federal Bureau of Investigation (FBI) have been mandated to develop and establish a wide range of unprecedented capabilities for providing scientific and technical forensic services to investigations involving hazardous chemical, biological, and radiological materials, including extremely dangerous chemical and biological warfare agents. Pacific Northwest National Laboratory (PNNL) has developed a portable, hand-held, hazardous materials acoustic inspection device (HAZAID) that provides noninvasive container interrogation and material identification capabilities using nondestructive ultrasonic velocity and attenuation measurements. Due to the wide variety of fluids as well as container sizes and materials, the need for high measurement sensitivity and advanced ultrasonic measurement techniques were identified. The HAZAID prototype was developed using a versatile electronics platform, advanced ultrasonic wave propagation methods, and advanced signal processing techniques. This paper primarily focuses on the ultrasonic measurement methods and signal processing techniques incorporated into the HAZAID prototype. High bandwidth ultrasonic transducers combined with the advanced pulse compression technique allowed researchers to 1) impart large amounts of energy, 2) obtain high signal-to-noise ratios, and 3) obtain accurate and consistent time-of-flight (TOF) measurements through a variety of highly attenuative containers and fluid media. Results of this feasibility study demonstrated that the HAZAID experimental measurement technique also provided information regarding container properties, which will be utilized in future container-independent measurements of hidden liquids.

Tucker, Brian J.; Diaz, Aaron A.; Eckenrode, Brian A.

2006-03-16

399

Prototype Instrument for Noninvasive Ultrasonic Inspection and Indentification of Fluids in Sealed Containers  

SciTech Connect

Government agencies and homeland security related organizations have identified the need to develop and establish a wide range of unprecedented capabilities for providing scientific and technical forensic services to investigations involving hazardous chemical, biological, and radiological materials, including extremely dangerous chemical and biological warfare agents. Pacific Northwest National Laboratory (PNNL) has developed a prototype portable, hand-held, hazardous materials acoustic inspection prototype that provides noninvasive container interrogation and material identification capabilities using nondestructive ultrasonic velocity and attenuation measurements. Due to the wide variety of fluids as well as container sizes and materials encountered in various law enforcement inspection activities, the need for high measurement sensitivity and advanced ultrasonic measurement techniques were identified. The prototype was developed using a versatile electronics platform, advanced ultrasonic wave propagation methods, and advanced signal processing techniques. This paper primarily focuses on the ultrasonic measurement methods and signal processing techniques incorporated into the prototype. High bandwidth ultrasonic transducers combined with an advanced pulse compression technique allowed researchers to 1) obtain high signal-to-noise ratios and 2) obtain accurate and consistent time-of-flight (TOF) measurements through a variety of highly attenuative containers and fluid media. Results of work conducted in the laboratory have demonstrated that the prototype experimental measurement technique also provided information regarding container properties, which will be utilized in future container-independent measurements of hidden liquids.

Tucker, Brian J.; Diaz, Aaron A.; Eckenrode, Brian A.

2006-08-01

400

Advanced ultrasonic measurement methodology for non-invasive interrogation and identification of fluids in sealed containers  

NASA Astrophysics Data System (ADS)

Government agencies and homeland security related organizations have identified the need to develop and establish a wide range of unprecedented capabilities for providing scientific and technical forensic services to investigations involving hazardous chemical, biological, and radiological materials, including extremely dangerous chemical and biological warfare agents. Pacific Northwest National Laboratory (PNNL) has developed a prototype portable, hand-held, hazardous materials acoustic inspection prototype that provides noninvasive container interrogation and material identification capabilities using nondestructive ultrasonic velocity and attenuation measurements. Due to the wide variety of fluids as well as container sizes and materials encountered in various law enforcement inspection activities, the need for high measurement sensitivity and advanced ultrasonic measurement techniques were identified. The prototype was developed using a versatile electronics platform, advanced ultrasonic wave propagation methods, and advanced signal processing techniques. This paper primarily focuses on the ultrasonic measurement methods and signal processing techniques incorporated into the prototype. High bandwidth ultrasonic transducers combined with an advanced pulse compression technique allowed researchers to 1) obtain high signal-to-noise ratios and 2) obtain accurate and consistent time-of-flight (TOF) measurements through a variety of highly attenuative containers and fluid media. Results of work conducted in the laboratory have demonstrated that the prototype experimental measurement technique also provided information regarding container properties, which will be utilized in future container-independent measurements of hidden liquids.

Tucker, Brian J.; Diaz, Aaron A.; Eckenrode, Brian A.

2006-03-01

401

Prototype instrument for noninvasive ultrasonic inspection and identification of fluids in sealed containers  

NASA Astrophysics Data System (ADS)

Government agencies and homeland security related organizations have identified the need to develop and establish a wide range of unprecedented capabilities for providing scientific and technical forensic services to investigations involving hazardous chemical, biological, and radiological materials, including extremely dangerous chemical and biological warfare agents. Pacific Northwest National Laboratory (PNNL) has developed a prototype portable, handheld, hazardous materials acoustic inspection prototype that provides noninvasive container interrogation and material identification capabilities using nondestructive ultrasonic velocity and attenuation measurements. Due to the wide variety of fluids as well as container sizes and materials encountered in various law enforcement inspection activities, the need for high measurement sensitivity and advanced ultrasonic measurement techniques were identified. The prototype was developed using a versatile electronics platform, advanced ultrasonic wave propagation methods, and advanced signal processing techniques. This paper primarily focuses on the ultrasonic measurement methods and signal processing techniques incorporated into the prototype. High bandwidth ultrasonic transducers combined with an advanced pulse compression technique allowed researchers to 1) obtain high signal-to-noise ratios and 2) obtain accurate and consistent time-of-flight (TOF) measurements through a variety of highly attenuative containers and fluid media. Results of work conducted in the laboratory have demonstrated that the prototype experimental measurement technique also provided information regarding container properties, which will be utilized in future container-independent measurements of hidden liquids.

Tucker, Brian J.; Diaz, Aaron A.; Eckenrode, Brian A.

2006-05-01

402

Advanced ultrasonic measurement methodology for non-invasive interrogation and identification of fluids in sealed containers  

SciTech Connect

Government agencies and homeland security related organizations have identified the need to develop and establish a wide range of unprecedented capabilities for providing scientific and technical forensic services to investigations involving hazardous chemical, biological, and radiological materials, including extremely dangerous chemical and biological warfare agents. Pacific Northwest National Laboratory (PNNL) has developed a prototype portable, hand-held, hazardous materials acoustic inspection prototype that provides noninvasive container interrogation and material identification capabilities using nondestructive ultrasonic velocity and attenuation measurements. Due to the wide variety of fluids as well as container sizes and materials encountered in various law enforcement inspection activities, the need for high measurement sensitivity and advanced ultrasonic measurement techniques were identified. The prototype was developed using a versatile electronics platform, advanced ultrasonic wave propagation methods, and advanced signal processing techniques. This paper primarily focuses on the ultrasonic measurement methods and signal processing techniques incorporated into the prototype. High bandwidth ultrasonic transducers combined with an advanced pulse compression technique allowed researchers to 1) obtain high signal-to-noise ratios and 2) obtain accurate and consistent time-of-flight (TOF) measurements through a variety of highly attenuative containers and fluid media. Results of work conducted in the laboratory have demonstrated that the prototype experimental measurement technique also provided information regarding container properties, which will be utilized in future container-independent measurements of hidden liquids.

Tucker, Brian J.; Diaz, Aaron A.; Eckenrode, Brian A.

2006-05-01

403

Determination of physicochemical properties of diacylglycerol oil at high pressure by means of ultrasonic methods.  

PubMed

The purpose of the paper is to address, using ultrasonic methods, the impact of temperature and pressure on the physicochemical properties of liquids on the example of diacylglycerol (DAG) oil. The paper presents measurements of sound velocity, density and volume of DAG oil sample in the pressure range from atmospheric pressure up to 0.6GPa and at temperatures ranging from 20 to 50°C. Sound speed measurements were performed in an ultrasonic setup with a DAG oil sample located in the high-pressure chamber. An ultrasonic method that uses cross-correlation method to determine the time-of-flight of the ultrasonic pulses through the liquid was employed to measure the sound velocity in DAG oil. This method is fast and reliable tool for measuring sound velocity. The DAG oil density at high pressure was determined from the monitoring of sample volume change. The adiabatic compressibility and isothermal compressibility have been calculated on the basis of experimental data. Discontinuities in isotherms of the sound speed versus pressure point to the existence of phase transitions in DAG oil. The ultrasonic method presented in this study can be applied to investigate the physicochemical parameters of other liquids not only edible oils. PMID:25017363

Kie?czy?ski, Piotr; Szalewski, Marek; Balcerzak, Andrzej; Wieja, Krzysztof; Malanowski, Aleksander; Ko?ciesza, Rafa?; Tarakowski, Rafa?; Rostocki, Aleksander J; Siegoczy?ski, Ryszard M

2014-12-01

404

Cutting head for ultrasonic lithotripsy  

NASA Technical Reports Server (NTRS)

A cutting head for attachment to the end of the wire probe of an ultrasonic kidney stone disintegration instrument is described. The cutting head has a plurality of circumferentially arranged teeth formed at one end thereof to provide a cup shaped receptacle for kidney stones encountered during the disintegration procedure. An integral reduced diameter collar diminishes stress points in the wire and reduce breakage thereof.

Anguluo, E. D.; Goodfriend, R. (inventors)

1985-01-01

405

Ultrasonic Thermometry for Nuclear Reactors  

Microsoft Academic Search

Ultrasonic thermometry, based on the temperature dependence of sound velocity in solids, has been demonstrated under ideal laboratory conditions beyond 6000R. Integrated fluxes (nvt) of 2.6 ?? 1019 fast and 8.7 ?? 1019 thermal do not perturb the velocity\\/temperature relationship. Ta protective sheaths prevented carbon contamination for 1 hr at 5100R, in a program simulating temperature measurements in the graphite\\/hydrogen

L. C. Lynnworth; E. H. Carnevale; M. S. McDonough; S. S. Fam

1969-01-01

406

Ultrasonic Attenuation in Zircaloy-4  

SciTech Connect

In this work the relationship between Zircaloy-4 grain size and ultrasonic attenuation behavior was studied for longitudinal waves in the frequency range of 10-90 MHz. The attenuation was analyzed as a function of frequency for samples with different mechanical and heat treatments having recrystallized and Widmanstatten structures with different grain size. The attenuation behavior was analyzed by different scattering models, depending on grain size, wavelength and frequency.

Gomez, M.P. [Departamento de Ingenieria Electrica, Facultad Regional Buenos Aires, Universidad Tecnologica Nacional, Medrano 951 (C1179AAQ), Buenos Aires (Argentina); Banchik, A.D. [Grupo LMFAE, CAE, Comision Nacional de Energia Atomica, Presbitero Luis Gonzalez y Aragon 15 (B1802AYA), Ezeiza, Buenos Aires (Argentina); Lopez Pumarega, M.I. [Grupo de Ondas Elasticas, UA ENDE, CAC, Comision Nacional de Energia Atomica, Av. General Paz 1499 (1650) San Martin, Buenos Aires (Argentina); Ruzzante, J.E. [Departamento de Ingenieria Electrica, Facultad Regional Buenos Aires, Universidad Tecnologica Nacional, Medrano 951 (C1179AAQ), Buenos Aires (Argentina); Grupo de Ondas Elasticas, UA ENDE, CAC, Comision Nacional de Energia Atomica, Av. General Paz 1499 (1650) San Martin, Buenos Aires (Argentina)

2005-04-09

407

High temperature ultrasonic transducers: review  

Microsoft Academic Search

The problems of development of high-temperature ultrasonic transducers for modern science and technology applications are analysed. More than 10 piezoelectric materials suitable for operation at high temperatures are overviewed. It is shown that bismuth titanate based piezoelectric elements are most promisable. Bonding methods of piezoelectric elements to a protector and backing are discussed. Thermosonic gold-to-gold bonding is most modern and

R. Ka; A. Voleišis; B. Voleišien?

2008-01-01

408

Nonlinearities in ultrasonic flow measurement  

Microsoft Academic Search

The governing equations of flow acoustics including nonlinearities are solved and analyzed in terms of ultrasonic flow-measurement properties. The effect of nonlinearities for sound propagation is expected to be most significant for gas-flow measurement applications as gas-sound speeds are much smaller while fluid flows generally are much higher in the corresponding case of liquid-flow measurement applications. The equation framework is

M. Willatzen; H. Kamath

2008-01-01

409

Development of enhanced ultrasonic imaging for in-situ inspection of a tension-stressed threaded fastener  

Microsoft Academic Search

A laboratory system was developed that utilized an ultrasonic pulse-echo technique to detect very small cracks emanating from the thread root of a tensile-stressed fastener. Primary benefits were (1) the ability to inspect the fastener without its removal from the structure, (2) much improved detection sensitivity to small cracks, and (3) easy interpretation of data. The fastener of interest had

Morris S. Good; Robert V. Harris; James R. Skorpik; Allan F. Pardini; Christopher M. Smith; Robert E. Bowey; Aaron A. Diaz; Brion J. Burghard; Kayte M. Judd; Justus D. Adamson

2000-01-01

410

PSPICE SIMULATION OF TRANSIENT RESPONSES OF TRANSDUCERS AND SPIKE GENERATORS INCLUDED IN E\\/R ULTRASONIC SYSTEMS  

Microsoft Academic Search

The global performance of ultrasonic emitting-receiving stages is influenced by the behavior of their respective electronic elements. In typical pulsed driving-receiving systems, present in commercial equipment employed in NDE or medical imaging, the electronic components notably condition the characteristics of the mechanical and electrical outputs under different operating conditions. This paper presents some PSPICE electric diagrams representing the piezoelectric transduction

SAN EMETERIO

411

A Novel Ultrasonic Method for Characterizing Microstructural Gradients in Tubular Structures  

NASA Technical Reports Server (NTRS)

Ultrasonic velocity and time-of-flight (TOF) imaging that uses back surface reflections to gage volumetric material quality is highly suited for quantitative characterization of microstructural gradients including those due to pore fraction, density, fiber fraction, and chemical composition variations. However, a weakness of conventional pulse echo ultrasonic velocity and TOF imaging is that the image shows the effects of thickness as well as microstructural variations, unless the part is uniformly thick. This limits this imaging method's usefulness in practical applications. Prior studies have described a pulse echo TOF based ultrasonic imaging method that requires using a single transducer in combination with a reflector plate placed behind samples which, eliminates the effect of thickness variation in the image. In those studies, this method was successful at isolating ultrasonic variations due to material in plate like samples of silicon nitride, metal matrix composite, and polymer matrix composite. In this study, the method is engineered for inspection of more complex shaped structures- those having (hollow) tubular or curved geometry. The experimental inspection technique and results are described as applied to a polymer matrix composite "proof of concept" tube that contains machined patches of various depths and an as manufactured monolithic silicon nitride ceramic tube that might be used in "real world" applications.

Roth, Don J.; Carney, Dorothy V.; Baaklini, George Y.; Bodis, James R.; Rauser, Richard W.

1998-01-01

412

Flexible piezopolymer ultrasonic guided wave arrays.  

PubMed

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 develop an array design that is simpler to manufacture and attach to pipelines compared to the current piezoceramic design. The design considerations for a flexible piezopolymer-based array are discussed in this paper along with the basic principles behind the selection of the array element width and spacing. The performance of a piezoceramic and piezopolymer array, with identical element spacing and width, are compared at four different frequencies. Tests were undertaken on a carbon steel pipe with a simulated defect. Evaluation of the different arrays was performed in terms of the defect response, in terms of amplitude, of the lower-order axisymmetric modes. It is shown that while the piezopolymer array provides comparable sensitivity to the piezoceramic array, the amplitude of the signals reflected from the simulated defect are 30 dB lower compared to those generated using the piezoceramic array. PMID:16846154

Hay, Thomas R; Rose, Joseph L

2006-06-01

413

Ultrasonic NDE of Multilayered Structures  

SciTech Connect

This project developed ultrasonic nondestructive evaluation techniques based on guided and bulk waves in multilayered structures using arrays. First, a guided wave technique was developed by preferentially exciting dominant modes with energy in the layer of interest via an ultrasonic array. Second, a bulk wave technique uses Fermat's principle of least time as well as wave-based properties to reconstruct array data and image the multilayered structure. The guided wave technique enables the inspection of inaccessible areas of a multilayered structure without disassembling it. Guided waves propagate using the multilayer as a waveguide into the inaccessible areas from an accessible position. Inspecting multi-layered structures with a guided wave relies on exciting modes with sufficient energy in the layer of interest. Multilayered structures are modeled to determine the possible modes and their distribution of energy across the thickness. Suitable modes were determined and excited by designing arrays with the proper element spacing and frequency. Bulk wave imaging algorithms were developed to overcome the difficulties of multiple reflections and refractions at interfaces. Reconstruction algorithms were developed to detect and localize flaws. A bent-ray algorithm incorporates Fermat's principle to correct time delays in the ultrasonic data that result from the difference in wave speeds in each layer and refractions at the interfaces. A planar wave-based algorithm was developed using the Green function for the multilayer structure to enhance focusing on reception for improved imaging.

Quarry, M J; Fisher, K A; Lehman, S K

2005-02-14

414

Flexible ultrasonic pipe inspection apparatus  

DOEpatents

A flexible, modular ultrasonic pipe inspection apparatus, comprises a flexible, hollow shaft that carries a plurality of modules, including at least one rotatable ultrasonic transducer, a motor/gear unit, and a position/signal encoder. The modules are connected by flexible knuckle joints that allow each module of the apparatus to change its relative orientation with respect to a neighboring module, while the shaft protects electrical wiring from kinking or buckling while the apparatus moves around a tight corner. The apparatus is moved through a pipe by any suitable means, including a tether or drawstring attached to the nose or tail, differential hydraulic pressure, or a pipe pig. The rotational speed of the ultrasonic transducer and the forward velocity of the apparatus are coordinated so that the beam sweeps out the entire interior surface of the pipe, enabling the operator to accurately assess the condition of the pipe wall and determine whether or not leak-prone corrosion damage is present. 7 figs.

Jenkins, C.F.; Howard, B.D.

1998-06-23

415

Ultrasonic Nondestructive Characterization of Adhesive Bonds  

NASA Technical Reports Server (NTRS)

Qualitative measurements of adhesion or binding forces can be accomplished, for example, by using the reflection coefficient of an ultrasound or by using thermal waves (Light and Kwun, 1989, Achenbach and Parikh, 1991, and Bostrom and wickham, 1991). However, a quantitative determination of binding forces is rather difficult. It has been observed that higher harmonics of the fundamental frequency are generated when an ultrasound passes through a nonlinear material. It seems that such non-linearity can be effectively used to characterize the bond strength. Several theories have been developed to model this nonlinear effect (Adler and Nagy, 1991; Achenbach and Parikh, 1991; Parikh and Achenbach, 1992; and Hirose and Kitahara, 1992; Anastasi and Roberts, 1992). Based on a microscopic description of the nonlinear interface binding force, a quantitative method was presented by Pangraz and Arnold (1994). Recently, Tang, Cheng and Achenbach (1997) made a comparison between the experimental and simulated results based on this theoretical model. A water immersion mode-converted shear wave through-transmission setup was used by Berndt and Green (1997) to analyze the nonlinear acoustic behavior of the adhesive bond. In this project, the nonlinear responses of an adhesive joint was investigated through transmission tests of ultrasonic wave and analyzed by the finite element simulations. The higher order harmonics were obtained in the tests. It is found that the amplitude of higher harmonics increases as the aging increases, especially the 3dorder harmonics. Results from the numerical simulation show that the material nonlinearity does indeed generate higher order harmonics. In particular, the elastic-perfect plastic behavior generates significant 3rd and 5th order harmonics.

Qu, Jianmin

1997-01-01

416

Ultrasonic attenuation of biomaterials for compensation in photoacoustic imaging  

NASA Astrophysics Data System (ADS)

Ultrasonic attenuation in biomaterials limits the quality and resolution of ultrasonic imaging. This work presents a simple and reliable method to investigate acoustic attenuation of biological tissue samples and liquids in order to improve reconstruction algorithms for photoacoustic imaging. For this purpose broadband high-frequency single transmission measurements were performed. The spectra of the acquired signals were compared to reference measurements in distilled water. Unfocused broadband piezoelectric transducers were used as ultrasound source and detector. Moreover, laser generated ultrasound, which provides more intensity and signals with higher bandwidth, was used to measure acoustic attenuation. Only few studies concerned with attenuation of fat tissue performed broadband high frequency measurements and to our knowledge none of those used the simple and reliable single transmission approach with unfocused ultrasound. Our results for acoustic attenuation in olive oil show good agreement with literature. Many studies indicate linear frequency increase of attenuation of fat tissue. However, we observed significant non-linear frequency behaviour of porcine subcutaneous fat tissue at room temperature with a power-law exponent of around 1.45.

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

2011-03-01

417

Through-thickness ultrasonic characterization of wood and  

E-print Network

Through-thickness ultrasonic characterization of wood and agricultural fiber composites Ronnie YOSBusingathroughtransmission ultrasonic technique. This evaluation presents a potential quality control tool for the manufacturing

418

Ultrasonic Nondestructive Evaluation Techniques Applied to the Quantitative Characterization of Textile Composite Materials  

NASA Technical Reports Server (NTRS)

In this Progress Report, we describe our further development of advanced ultrasonic nondestructive evaluation methods applied to the characterization of anisotropic materials. We present images obtained from experimental measurements of ultrasonic diffraction patterns transmitted through water only and transmitted through water and a thin woven composite. All images of diffraction patterns have been included on the accompanying CD-ROM in the JPEG format and Adobe TM Portable Document Format (PDF), in addition to the inclusion of hardcopies of the images contained in this report. In our previous semi-annual Progress Report (NAG 1-1848, December, 1996), we proposed a simple model to simulate the effect of a thin woven composite on an insonifying ultrasonic pressure field. This initial approach provided an avenue to begin development of a robust measurement method for nondestructive evaluation of anisotropic materials. In this Progress Report, we extend that work by performing experimental measurements on a single layer of a five-harness biaxial woven composite to investigate how a thin, yet architecturally complex, material interacts with the insonifying ultrasonic field. In Section 2 of this Progress Report we describe the experimental arrangement and methods for data acquisition of the ultrasonic diffraction patterns upon transmission through a thin woven composite. We also briefly describe the thin composite specimen investigated. Section 3 details the analysis of the experimental data followed by the experimental results in Section 4. Finally, a discussion of the observations and conclusions is found in Section 5.

Miller, James G.

1997-01-01

419

Sputtered ZnO film on aluminium foils for flexible ultrasonic transducers.  

PubMed

Nanocrystalline ZnO films with both C-axis vertical grown and inclined angled grown were sputter-deposited onto aluminium foils (50 ?m thick) and characterised for using as flexible ultrasonic transducers. As-deposited C-axis grown ZnO films were annealed at different temperatures up to 600 °C to enhance film crystallinity and reduce film stress. The C-axis grown ZnO film on the Al foil were bonded onto steel plates, and the pulse-echo tests verified a good performance (with dominant longitudinal waves) of the ultrasonic transducers made from both as-deposited and post-annealed films. Inclined angled ZnO films on the Al foil glued onto steel plates generated mixed shear and longitudinal waves in the pulse-echo test. PMID:24924786

Zhou, X S; Zhao, C; Hou, R; Zhang, J; Kirk, K J; Hutson, D; Guo, Y J; Hu, P A; Peng, S M; Zu, X T; Fu, Y Q

2014-09-01

420

Time-of-flight modeling of transversal ultrasonic scan of wood.  

PubMed

Time-of-flight is a time for an ultrasonic pulse to cross a sample. It contains valuable information about the mechanical properties of a material. For the ultrasonic pulse propagating in wood perpendicular to the grain the relation between the time-of-flight and the elastic constants is rather complex due to the strong anisotropicity of wood. With the help of some assumptions this relation can be established from the elastic theory. The analytical calculation results in a function which represents a change of time-of-flight when the direction of propagation shifts from the radial to the tangential direction while scanning a board crosswise. The function takes into account the location of the pith and the geometry of the growth rings. The measurement performed on a sample of European spruce confirms the theoretical prediction. PMID:24907804

Yaitskova, Natalia; van de Kuilen, Jan Willem

2014-06-01

421

The role of the reflection coefficient in precision measurement of ultrasonic attenuation  

NASA Technical Reports Server (NTRS)

Ultrasonic attenuation measurements using contact, pulse-echo techniques are sensitive to surface roughness and couplant thickness variations. This can reduce considerable inaccuracies in the measurement of the attenuation coefficient for broadband pulses. Inaccuracies arise from variations in the reflection coefficient at the buffer-couplant-sample interface. The reflection coefficient is examined as a function of the surface roughness and corresponding couplant thickness variations. Interrelations with ultrasonic frequency are illustrated. Reliable attenuation measurements are obtained only when the frequency dependence of the reflection coefficient is incorporated in signal analysis. Data are given for nickel 200 samples and a silicon nitride ceramic bar having surface roughness variations in the 0.3 to 3.0 microns range for signal bandwidths in the 50 to 100 MHz range.

Generazio, E. R.

1984-01-01

422

Pulse Voltammetry  

NASA Astrophysics Data System (ADS)

The idea of imposing potential pulses and measuring the currents at the end of each pulse was proposed by Barker in a little-known journal as early as in 1958 [1]. However, the first reliable trouble-free and affordable polarographs offering voltammetric pulse techniques appeared on the market only in the 1970s. This delay was due to some limitations on the electronic side. In the 1990s, again substantial progress in electrochemical pulse instrumentation took place. This was related to the introduction of microprocessors, computers, and advanced software.

Stojek, Zbigniew

423

Nonlinear transmission line based electron beam driver  

SciTech Connect

Gated field emission cathodes can provide short electron pulses without the requirement of laser systems or cathode heating required by photoemission or thermionic cathodes. The large electric field requirement for field emission to take place can be achieved by using a high aspect ratio cathode with a large field enhancement factor which reduces the voltage requirement for emission. In this paper, a cathode gate driver based on the output pulse train from a nonlinear transmission line is experimentally demonstrated. The application of the pulse train to a tufted carbon fiber field emission cathode generates short electron pulses. The pulses are approximately 2 ns in duration with emission currents of several mA, and the train contains up to 6 pulses at a frequency of 100 MHz. Particle-in-cell simulation is used to predict the characteristic of the current pulse train generated from a single carbon fiber field emission cathode using the same technique.

French, David M.; Hoff, Brad W.; Tang Wilkin; Heidger, Susan; Shiffler, Don [Directed Energy Directorate, Air Force Research Laboratory, Kirtland AFB, New Mexico 87117 (United States); Allen-Flowers, Jordan [Program in Applied Mathematics, University of Arizona, Tucson, Arizona 85721 (United States)

2012-12-15

424

Nonlinear transmission line based electron beam driver.  

PubMed

Gated field emission cathodes can provide short electron pulses without the requirement of laser systems or cathode heating required by photoemission or thermionic cathodes. The large electric field requirement for field emission to take place can be achieved by using a high aspect ratio cathode with a large field enhancement factor which reduces the voltage requirement for emission. In this paper, a cathode gate driver based on the output pulse train from a nonlinear transmission line is experimentally demonstrated. The application of the pulse train to a tufted carbon fiber field emission cathode generates short electron pulses. The pulses are approximately 2 ns in duration with emission currents of several mA, and the train contains up to 6 pulses at a frequency of 100 MHz. Particle-in-cell simulation is used to predict the characteristic of the current pulse train generated from a single carbon fiber field emission cathode using the same technique. PMID:23277977

French, David M; Hoff, Brad W; Tang, Wilkin; Heidger, Susan; Allen-Flowers, Jordan; Shiffler, Don

2012-12-01

425

Prion transmission  

PubMed Central

Prion diseases range from being highly infectious, for example scrapie and CWD, which show facile transmission between susceptible individuals, to showing negligible horizontal transmission, such as BSE and CJD, which are spread via food or iatrogenically, respectively. Scrapie and CWD display considerable in vivo dissemination, with PrPSc and infectivity being found in a range of peripheral tissues. This in vivo dissemination appears to facilitate the recently reported excretion of prion through multiple routes such as from skin, feces, urine, milk, nasal secretions, saliva and placenta. Furthermore, excreted scrapie and CWD agent is detected within environmental samples such as water and on the surfaces of inanimate objects. The cycle of “uptake of prion from the environment—widespread in vivo prion dissemination—prion excretion—prion persistence in the environment” is likely to explain the facile transmission and maintenance of these diseases within wild and farmed populations over many years. PMID:20948292

Maddison, Ben C

2010-01-01

426

Study on the compound multifrequency ultrasonic transducer in flexural vibration.  

PubMed

A new type of compound multifrequency ultrasonic transducer is analyzed in this paper. The compound multifrequency ultrasonic transducer consists of two sandwiched ultrasonic transducers and a rectangular radiator. In virtue of the coupling between longitudinal vibration of the sandwiched ultrasonic transducers and flexural vibration of the rectangular radiator, the compound multifrequency ultrasonic transducer can produce several resonance frequencies. Some compound multifrequency ultrasonic transducers are designed and simulated by finite element method (ANSYS), and modal shapes and harmonic response are analyzed. The compound multifrequency ultrasonic transducers are designed and manufactured. The resonance frequencies are measured and compared with the numerical results. The effect of the geometrical dimensions of the compound multifrequency ultrasonic transducer and the location of two sandwiched ultrasonic transducers on the compound multifrequency ultrasonic transducer is discussed. It is shown experimentally and numerically that the compound multifrequency ultrasonic transducer has several resonance frequencies. PMID:18267322

Xian, Xiaojun; Lin, Shuyu

2008-07-01

427

Ultrasonic measurement of solid\\/liquid interface position during solidification and melting of metals  

Microsoft Academic Search

The use of pulse-echo ultrasonic flaw detectors to detect the presence and location of cracks, voids, and other discontinuities in metals and non-metal is well known. The solid-liquid interface in a melting or freezing metal can also be considered as a discontinuity, in that there is a measurable difference in both sound velocity and density across the interface. For normal

R. L. Parker

1982-01-01

428

On-line ultrasonic monitoring of a die-casting process using buffer rods  

Microsoft Academic Search

On-line ultrasonic monitoring of die casting of an aluminum plate with steps of different thicknesses is studied using pulse-echo techniques. Clad buffer rods are inserted into the die wall for the monitoring. The flow front of molten aluminum inside the die has been probed by a two-channel acquisition system with a time resolution up to 1 ms. This information may

C.-K. Jen; B. Cao; K. T. Nguyen; C. A. Loong; J.-G. Legoux

1997-01-01

429

Ultrasonic study of the elastic and nonlinear acoustic properties of ceramic aluminum nitride  

Microsoft Academic Search

Pulse-echo-overlap measurements of ultrasonic wave velocity have been used to determine the elastic stiffness moduli and related elastic properties of aluminum nitride (AlN) ceramic samples as functions of temperature in the range 100–295 K and hydrostatic pressure up to 0.2 GPa at room temperature. Aluminum nitride is an elastically stiff but light ceramic: at 295 K, the longitudinal stiffness (CL),

S. P. Dodd; G. A. Saunders; M. Cankurtaran; B. James

2001-01-01

430

Rotorcraft transmissions  

NASA Technical Reports Server (NTRS)

Highlighted here is that portion of the Lewis Research Center's helicopter propulsion systems program that deals with drive train technology and the related mechanical components. The major goals of the program are to increase life, reliability, and maintainability, to reduce weight, noise, and vibration, and to maintain the relatively high mechanical efficiency of the gear train. The current activity emphasizes noise reduction technology and analytical code development, followed by experimental verification. Selected significant advances in technology for transmissions are reviewed, including advanced configurations and new analytical tools. Finally, the plan for transmission research in the future is presented.

Coy, John J.

1990-01-01

431

Monitoring the setting of concrete containing blast-furnace slag by measuring the ultrasonic p-wave velocity  

Microsoft Academic Search

Ultrasonic transmission measurements allow the continuous monitoring of the setting of both mortar and concrete samples, which is important to determine for instance the formwork removal time. However, aspects such as the cause of the low initial velocity, the relation between the velocity and the setting times and the effect of cement type or cement replacing additives are still under

Nicolas Robeyst; Elke Gruyaert; Christian U. Grosse; Nele De Belie

2008-01-01

432

In sodium tests of ultrasonic transducers  

Microsoft Academic Search

Ultrasonic techniques are seen as suitable candidates for the in-service inspection and for the continuous surveillance of sodium cooled reactors (SFR). These techniques need the development and the qualification of immersed ultrasonic transducers, and materials. This paper presents some developments performed by CEA (DTN and LIST) and AREVA (NDE Solutions), and some results.

C. Lhuillier; O. Descombin; F. Baque; B. Marchand; J. F. Saillant; J. M. Augem

2011-01-01

433

Transducer Joint for Kidney-Stone Ultrasonics  

NASA Technical Reports Server (NTRS)

Ultrasonic therapy for kidney stones improved by new way of connecting wire-probe ultrasonic waveguide to transducer. Improved mounting allows joint to last long enough for effective treatment. Sheath and rubber dampers constrain lateral vibration of wire waveguide. Combination of V-shaped mounting groove, sheath, and rubber dampers increases life expectancy of wire 15 times or more.

Angulo, E. D.

1983-01-01

434

A novel multiple blade ultrasonic cutting device  

Microsoft Academic Search

In ultrasonic devices consisting of serially coupled tuned components, components whose tuned length dimension is large compared to other dimensions, or components with profiles designed for high gain, the response of the device during operation is often characterised by modal interactions, and especially the excitation of combination resonances. The effects on ultrasonic devices are high noise levels, component failures and

Andrea Cardoni; Margaret Lucas; Matthew Cartmell; Fannon Lim

2004-01-01

435

The AC parameters measurement system for ultrasonics  

Microsoft Academic Search

The AC response measurement system is presented. System structure, operation and main units operation are described. The connection setup for a few most common tasks is presented. The obtained results are given. It has been indicated that AC response can be investigated for ultrasonic preamplifier, matching transformer, system filters and ultrasonic transducers. The system is controlled by a personal computer

L. Svilainis

2006-01-01

436

Medical ultrasonic atomizer design parameters analysis  

Microsoft Academic Search

The battle in the fight against respiratory diseases, ultrasonic atomizer more widely used, but the design of the physical characteristics complex and has always been a challenge. Based on the deep analysis of ultrasonic atomization technology, according to the choice of the atomizer plate and the best working depth and put forward the choice standard of atomizer plate. Combined with

Zhengguang Zhang; Le-cai Cai

2010-01-01

437

Ultrasonic Abrasive Removal Of EDM Recast  

NASA Technical Reports Server (NTRS)

Ultrasonic abrasive process removes layer of recast material generated during electrical-discharge machining (EDM) of damper pocket on turbine blade. Form-fitted tool vibrated ultrasonically in damper pocket from which material removed. Vibrations activate abrasive in pocket. Amount of material removed controlled precisely.

Mandel, Johnny L.; Jacobson, Marlowe S.

1990-01-01

438

Ultrasonic characterization of single drops of liquids  

Microsoft Academic Search

Ultrasonic characterization of single drops of liquids. The present invention includes the use of two closely spaced transducers, or one transducer and a closely spaced reflector plate, to form an interferometer suitable for ultrasonic characterization of droplet-size and smaller samples without the need for a container. The droplet is held between the interferometer elements, whose distance apart may be adjusted,

Sinha; Dipen N

1998-01-01

439

Ultrasonic characterization of single drops of liquids  

Microsoft Academic Search

Ultrasonic characterization of single drops of liquids is disclosed. The present invention includes the use of two closely spaced transducers, or one transducer and a closely spaced reflector plate, to form an interferometer suitable for ultrasonic characterization of droplet-size and smaller samples without the need for a container. The droplet is held between the interferometer elements, whose distance apart may

Sinha

1998-01-01

440

Broadband, High-Temperature Ultrasonic Transducer  

NASA Technical Reports Server (NTRS)

Materials chosen for endurance at high temperatures and acoustic coupling and damping. Acoustic transducer designed to exhibit broad frequency response and to survive temperatures close to melting points of brazing alloys. Attached directly and continuously to hot object monitored ultrasonically: for example, it can be attached to relatively cool spot on workpiece during brazing for taking ultrasonic quality-control measurements.

Parker, F. Raymond; Winfree, William P.; Barrows, Danny A.

1995-01-01

441

Ultrasonic electrostatic actuators on a flexible substrate  

Microsoft Academic Search

We present a MEMS-based electrostatic actuator on a flexible substrate, made of Polyethylene Naphthalate (PEN), which emits acoustic waves at ultrasonic frequencies, aiming for an ultrasound microdevice for equipment inspection. The actuator has a suspended diaphragm, made of parylene, of 2–6 mm diameter and a 6 ?m gap between the diaphragm and substrate. A single actuator emits ultrasonic waves at

Sangpyeong Kim; Xu Zhang; Robin Daugherty; Ed Lee; George Kunnen; David R. Allee; Eric Forsythe; Junseok Chae

2012-01-01