Science.gov

Sample records for acoustic monitoring techniques

  1. An acoustic-array based structural health monitoring technique for wind turbine blades

    NASA Astrophysics Data System (ADS)

    Aizawa, Kai; Poozesh, Peyman; Niezrecki, Christopher; Baqersad, Javad; Inalpolat, Murat; Heilmann, Gunnar

    2015-04-01

    This paper proposes a non-contact measurement technique for health monitoring of wind turbine blades using acoustic beamforming techniques. The technique works by mounting an audio speaker inside a wind turbine blade and observing the sound radiated from the blade to identify damage within the structure. The main hypothesis for the structural damage detection is that the structural damage (cracks, edge splits, holes etc.) on the surface of a composite wind turbine blade results in changes in the sound radiation characteristics of the structure. Preliminary measurements were carried out on two separate test specimens, namely a composite box and a section of a wind turbine blade to validate the methodology. The rectangular shaped composite box and the turbine blade contained holes with different dimensions and line cracks. An acoustic microphone array with 62 microphones was used to measure the sound radiation from both structures when the speaker was located inside the box and also inside the blade segment. A phased array beamforming technique and CLEAN-based subtraction of point spread function from a reference (CLSPR) were employed to locate the different damage types on both the composite box and the wind turbine blade. The same experiment was repeated by using a commercially available 48-channel acoustic ring array to compare the test results. It was shown that both the acoustic beamforming and the CLSPR techniques can be used to identify the damage in the test structures with sufficiently high fidelity.

  2. Swept frequency acoustic interferometry technique for chemical weapons verification and monitoring

    SciTech Connect

    Sinha, D.N.; Anthony, B.W.; Lizon, D.C.

    1995-03-01

    Nondestructive evaluation (NDE) techniques are important for rapid on-site verification and monitoring of chemical munitions, such as artillery shells and bulk containers. Present NDE techniques provide only limited characterizations of such munitions. This paper describes the development of a novel noninvasive technique, swept-frequency acoustic interferometry (SFAI), that significantly enhances the capability of munitions characterizations. The SFAI technique allows very accurate and simultaneous determination of sound velocity and attenuation of chemical agents over a large frequency range inside artillery shells, in addition to determining agent density. The frequency-dependent sound velocity and attenuation can, in principle, provide molecular relaxation properties of the chemical agent. The same instrument also enables a direct fill-level measurement in bulk containers. Industrial and other applications of this general-purpose technique are also discussed.

  3. Acoustic techniques in nuclear safeguards

    SciTech Connect

    Olinger, C.T.; Sinha, D.N.

    1995-07-01

    Acoustic techniques can be employed to address many questions relevant to current nuclear technology needs. These include establishing and monitoring intrinsic tags and seals, locating holdup in areas where conventional radiation-based measurements have limited capability, process monitoring, monitoring containers for corrosion or changes in pressure, and facility design verification. These acoustics applications are in their infancy with respect to safeguards and nuclear material management, but proof-of-principle has been demonstrated in many of the areas listed.

  4. Effects of different analysis techniques and recording duty cycles on passive acoustic monitoring of killer whales.

    PubMed

    Riera, Amalis; Ford, John K; Ross Chapman, N

    2013-09-01

    Killer whales in British Columbia are at risk, and little is known about their winter distribution. Passive acoustic monitoring of their year-round habitat is a valuable supplemental method to traditional visual and photographic surveys. However, long-term acoustic studies of odontocetes have some limitations, including the generation of large amounts of data that require highly time-consuming processing. There is a need to develop tools and protocols to maximize the efficiency of such studies. Here, two types of analysis, real-time and long term spectral averages, were compared to assess their performance at detecting killer whale calls in long-term acoustic recordings. In addition, two different duty cycles, 1/3 and 2/3, were tested. Both the use of long term spectral averages and a lower duty cycle resulted in a decrease in call detection and positive pod identification, leading to underestimations of the amount of time the whales were present. The impact of these limitations should be considered in future killer whale acoustic surveys. A compromise between a lower resolution data processing method and a higher duty cycle is suggested for maximum methodological efficiency.

  5. Effects of different analysis techniques and recording duty cycles on passive acoustic monitoring of killer whales.

    PubMed

    Riera, Amalis; Ford, John K; Ross Chapman, N

    2013-09-01

    Killer whales in British Columbia are at risk, and little is known about their winter distribution. Passive acoustic monitoring of their year-round habitat is a valuable supplemental method to traditional visual and photographic surveys. However, long-term acoustic studies of odontocetes have some limitations, including the generation of large amounts of data that require highly time-consuming processing. There is a need to develop tools and protocols to maximize the efficiency of such studies. Here, two types of analysis, real-time and long term spectral averages, were compared to assess their performance at detecting killer whale calls in long-term acoustic recordings. In addition, two different duty cycles, 1/3 and 2/3, were tested. Both the use of long term spectral averages and a lower duty cycle resulted in a decrease in call detection and positive pod identification, leading to underestimations of the amount of time the whales were present. The impact of these limitations should be considered in future killer whale acoustic surveys. A compromise between a lower resolution data processing method and a higher duty cycle is suggested for maximum methodological efficiency. PMID:23968036

  6. Validation and verification of the acoustic emission technique for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Gagar, Daniel Omatsola

    The performance of the Acoustic Emission (AE) technique was investigated to establish its reliability in detecting and locating fatigue crack damage as well as distinguishing between different AE sources in potential SHM applications. Experiments were conducted to monitor the AE signals generated during fatigue crack growth in coupon 2014 T6 aluminium. The influence of stress ratio, stress range, sample geometry and whether or not the load spectrum was of constant or variable amplitude were all investigated. AE signals detected were correlated with values of applied cyclic load throughout the tests. Measurements of time difference of arrival were taken for assessment of errors in location estimates obtained using time of flight algorithms with a 1D location setup. At the onset of crack growth high AE Hit rates were observed for the first few millimetres after which they rapidly declined to minimal values for an extended period of crack growth. Another peak and then decline in AE Hit rates was observed for subsequent crack growth before yet another increase as the sample approached final failure.. AE signals were seen to occur in the lower two-thirds of the maximum load in the first few millimetres of crack growth before occurring at progressively smaller values as the crack length increased. A separate set of AE signals were observed close to the maximum cyclic stress throughout the entire crack growth process. At the failure crack length AE signals were generated across the entire loading range. Novel metrics were developed to statistically characterise variability of AE generation with crack growth and at particular crack lengths across different samples. A novel approach for fatigue crack length estimation was developed based on monitoring applied loads to the sample corresponding with generated AE signals. An acousto-ultrasonic method was used to calibrate the AE wave velocity in a representative wing-box structure which was used to successfully locate the

  7. Numerical Techniques in Acoustics

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J. (Compiler)

    1985-01-01

    This is the compilation of abstracts of the Numerical Techniques in Acoustics Forum held at the ASME's Winter Annual Meeting. This forum was for informal presentation and information exchange of ongoing acoustic work in finite elements, finite difference, boundary elements and other numerical approaches. As part of this forum, it was intended to allow the participants time to raise questions on unresolved problems and to generate discussions on possible approaches and methods of solution.

  8. Using Complementary Acoustic and Optical Techniques for Quantitative Monitoring of Biomolecular Adsorption at Interfaces

    PubMed Central

    Konradi, Rupert; Textor, Marcus; Reimhult, Erik

    2012-01-01

    The great wealth of different surface sensitive techniques used in biosensing, most of which claim to measure adsorbed mass, can at first glance look unnecessary. However, with each technique relying on a different transducer principle there is something to be gained from a comparison. In this tutorial review, different optical and acoustic evanescent techniques are used to illustrate how an understanding of the transducer principle of each technique can be exploited for further interpretation of hydrated and extended polymer and biological films. Some of the most commonly used surface sensitive biosensor techniques (quartz crystal microbalance, optical waveguide spectroscopy and surface plasmon resonance) are briefly described and five case studies are presented to illustrate how different biosensing techniques can and often should be combined. The case studies deal with representative examples of adsorption of protein films, polymer brushes and lipid membranes, and describe e.g., how to deal with strongly vs. weakly hydrated films, large conformational changes and ordered layers of biomolecules. The presented systems and methods are compared to other representative examples from the increasing literature on the subject. PMID:25586027

  9. Acoustic emission monitoring system

    DOEpatents

    Romrell, Delwin M.

    1977-07-05

    Methods and apparatus for identifying the source location of acoustic emissions generated within an acoustically conductive medium. A plurality of acoustic receivers are communicably coupled to the surface of the medium at a corresponding number of spaced locations. The differences in the reception time of the respective sensors in response to a given acoustic event are measured among various sensor combinations prescribed by the monitoring mode employed. Acoustic reception response encountered subsequent to the reception by a predetermined number of the prescribed sensor combinations are inhibited from being communicated to the processing circuitry, while the time measurements obtained from the prescribed sensor combinations are translated into a position measurement representative of the location on the surface most proximate the source of the emission. The apparatus is programmable to function in six separate and five distinct operating modes employing either two, three or four sensory locations. In its preferred arrangement the apparatus of this invention will re-initiate a monitoring interval if the predetermined number of sensors do not respond to a particular emission within a given time period.

  10. A novel technique for acoustic emission monitoring in civil structures with global fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Verstrynge, E.; Pfeiffer, H.; Wevers, M.

    2014-06-01

    The application of acoustic emission (AE)-based damage detection is gaining interest in the field of civil structural health monitoring. Damage progress can be detected and located in real time and the recorded AEs hold information on the fracture process which produced them. One of the drawbacks for on-site application in large-scale concrete and masonry structures is the relatively high attenuation of the ultrasonic signal, which limits the detection range of the AE sensors. Consequently, a large number of point sensors are required to cover a certain area. To tackle this issue, a global damage detection system, based on AE detection with a polarization-modulated, single mode fiber optic sensor (FOS), has been developed. The sensing principle, data acquisition and analysis in time and frequency domain are presented. During experimental investigations, this AE-FOS is applied for the first time as a global sensor for the detection of crack-induced AEs in a full-scale concrete beam. Damage progress is monitored during a cyclic four-point bending test and the AE activity, detected with the FOS, is related to the subsequent stages of damage progress in the concrete element. The results obtained with the AE-FOS are successfully linked to the mechanical behavior of the concrete beam and a qualitative correspondence is found with AE data obtained by a commercial system.

  11. Acoustic emission monitoring of polymer composite materials

    NASA Technical Reports Server (NTRS)

    Bardenheier, R.

    1981-01-01

    The techniques of acoustic emission monitoring of polymer composite materials is described. It is highly sensitive, quasi-nondestructive testing method that indicates the origin and behavior of flaws in such materials when submitted to different load exposures. With the use of sophisticated signal analysis methods it is possible the distinguish between different types of failure mechanisms, such as fiber fracture delamination or fiber pull-out. Imperfections can be detected while monitoring complex composite structures by acoustic emission measurements.

  12. Fatigue-crack monitoring in-flight using acoustic emission - hardware, technique, and testing

    SciTech Connect

    Hutton, P.H.; Skorpik, J.R.; Lemon, D.K.

    1981-07-01

    The three programs described represent a logical evolutionary process toward effective flaw surveillance in aircraft using AE. The Macchi tests showed that an AE system can withstand extended in-flight service and collect meaningful information relative to fatigue crack growth at a single specific location. The MIrage aircraft work seeks to extend the methods demonstrated on the Macchi into a more complex circumstance. We are now attempting to detect and locate crack growth at any of twenty fastener locations in a relatively complex geometry. The DARPA pattern recognition program seeks to develop signal identification capability that would pave the way for general monitoring of aircraft structures using AE to detect fatigue crack growth. It appears that AE technology may be capable of enhancing aircraft safety assurance while reducing inspection requirements with the associated costs.

  13. PORTABLE ACOUSTIC MONITORING PACKAGE (PAMP)

    SciTech Connect

    John L. Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Patrick Browning

    2004-07-20

    The Portable Acoustic Monitoring Package (PAMP) has been designed to record and monitor the acoustic signal in natural gas transmission lines. In particular the three acoustic signals associated with a line leak. The system is portable ({approx}30 lbs) and is designed for line pressures up to 1000 psi. It has become apparent that cataloging of the various background acoustic signals in natural gas transmission line is very important if a system to identify leak signals is to be developed. The low-pressure (0-200 psig) laboratory test phase has been completed and a number of field trials have been conducted. Before the cataloging phase could begin, a few problems identified in field trials identified had to be corrected such as: (1) Decreased microphone sensitivity at line pressures above 250 psig. (2) The inability to deal with large data sets collected when cataloging the variety of signals in a transmission line. (3) The lack of an available online acoustic calibration system. These problems have been solved and the WVU PAMP is now fully functional over the entire pressure range found in the Natural Gas transmission lines in this region. Field portability and reliability have been greatly improved. Data collection and storage have also improved to the point were the full acoustic spectrum of acoustic signals can be accurately cataloged, recorded and described.

  14. PORTABLE ACOUSTIC MONITORING PACKAGE (PAMP)

    SciTech Connect

    John l. Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Deepak Mehra

    2003-07-01

    The 1st generation acoustic monitoring package was designed to detect and analyze weak acoustic signals inside natural gas transmission lines. Besides a microphone it housed a three-inch diameter aerodynamic acoustic signal amplifier to maximize sensitivity to leak induced {Delta}p type signals. The theory and test results of this aerodynamic signal amplifier was described in the master's degree thesis of our Research Assistant Deepak Mehra who is about to graduate. To house such a large three-inch diameter sensor required the use of a steel 300-psi rated 4 inch weld neck flange, which itself weighed already 29 pounds. The completed 1st generation Acoustic Monitoring Package weighed almost 100 pounds. This was too cumbersome to mount in the field, on an access port at a pipeline shut-off valve. Therefore a 2nd generation and truly Portable Acoustic Monitor was built. It incorporated a fully self-contained {Delta}p type signal sensor, rated for line pressures up to 1000 psi with a base weight of only 6 pounds. This is the Rosemont Inc. Model 3051CD-Range 0, software driven sensor, which is believed to have industries best total performance. Its most sensitive unit was purchased with a {Delta}p range from 0 to 3 inch water. This resulted in the herein described 2nd generation: Portable Acoustic Monitoring Package (PAMP) for pipelines up to 1000 psi. Its 32-pound total weight includes an 18-volt battery. Together with a 3 pound laptop with its 4-channel data acquisition card, completes the equipment needed for field acoustic monitoring of natural gas transmission pipelines.

  15. Fault monitoring using acoustic emissions

    NASA Astrophysics Data System (ADS)

    Zhang, Danlu; Venkatesan, Gopal; Kaveh, Mostafa; Tewfik, Ahmed H.; Buckley, Kevin M.

    1999-05-01

    Automatic monitoring techniques are a means to safely relax and simplify preventive maintenance and inspection procedures that are expensive and necessitate substantial down time. Acoustic emissions (AEs), that are ultrasonic waves emanating from the formation or propagation of a crack in a material, provide a possible avenue for nondestructive evaluation. Though the characteristics of AEs have been extensively studied, most of the work has been done under controlled laboratory conditions at very low noise levels. In practice, however, the AEs are buried under a wide variety of strong interference and noise. These arise due to a number of factors that, other than vibration, may include fretting, hydraulic noise and electromagnetic interference. Most of these noise events are transient and not unlike AE signals. In consequence, the detection and isolation of AE events from the measured data is not a trivial problem. In this paper we present some signal processing techniques that we have proposed and evaluated for the above problem. We treat the AE problem as the detection of an unknown transient in additive noise followed by a robust classification of the detected transients. We address the problem of transient detection using the residual error in fitting a special linear model to the data. Our group is currently working on the transient classification using neural networks.

  16. The Development of Automated Detection Techniques for Passive Acoustic Monitoring as a Tool for Studying Beaked Whale Distribution and Habitat Preferences in the California Current Ecosystem

    NASA Astrophysics Data System (ADS)

    Yack, Tina M.

    California Bight (SCB). The preliminary measurement of the visually validated Baird's beaked whale echolocation signals recorded from the ship-based towed array were used as a basis for identifying Baird's signals in the seafloor-mounted autonomous recorder data. The passive acoustic detection algorithms for beaked whales developed using data from Chapters 2 and 3 were field tested during a three year period to test the reliability of acoustic beaked whale monitoring techniques and to use these methods to describe beaked whale habitat in the SCB. In 2009 and 2010, PAM methods using towed hydrophone arrays were tested. These methods proved highly effective for real-time detection of beaked whales in the SCB and were subsequently implemented in 2011 to successfully detect and track beaked whales during the ongoing Southern California Behavioral Response Study (SOCAL-BRS). The final step in this research was to utilize the passive acoustic detection techniques developed herin to predictively model beaked whale habitat use and preferences in the CCE. This chapter uses a multifaceted approach to model beaked whale encounter rates in the CCE. Beaked whale acoustic encounters are utilized to inform Generalized Additive Models (GAMs) of encounter rate for beaked whales in the CCE and compare these to visual based models. Acoustic and visual based models were independently developed for a small beaked whale group and Baird's beaked whales. Two models were evaluated for visual and acoustic encounters, one that also included Beaufort sea state as a predictor variable in addition to those listed and one that did not include Beaufort sea state. (Abstract shortened by UMI.)

  17. Non-Destructive Evaluation for Corrosion Monitoring in Concrete: A Review and Capability of Acoustic Emission Technique.

    PubMed

    Zaki, Ahmad; Chai, Hwa Kian; Aggelis, Dimitrios G; Alver, Ninel

    2015-08-05

    Corrosion of reinforced concrete (RC) structures has been one of the major causes of structural failure. Early detection of the corrosion process could help limit the location and the extent of necessary repairs or replacement, as well as reduce the cost associated with rehabilitation work. Non-destructive testing (NDT) methods have been found to be useful for in-situ evaluation of steel corrosion in RC, where the effect of steel corrosion and the integrity of the concrete structure can be assessed effectively. A complementary study of NDT methods for the investigation of corrosion is presented here. In this paper, acoustic emission (AE) effectively detects the corrosion of concrete structures at an early stage. The capability of the AE technique to detect corrosion occurring in real-time makes it a strong candidate for serving as an efficient NDT method, giving it an advantage over other NDT methods.

  18. Non-Destructive Evaluation for Corrosion Monitoring in Concrete: A Review and Capability of Acoustic Emission Technique

    PubMed Central

    Zaki, Ahmad; Chai, Hwa Kian; Aggelis, Dimitrios G.; Alver, Ninel

    2015-01-01

    Corrosion of reinforced concrete (RC) structures has been one of the major causes of structural failure. Early detection of the corrosion process could help limit the location and the extent of necessary repairs or replacement, as well as reduce the cost associated with rehabilitation work. Non-destructive testing (NDT) methods have been found to be useful for in-situ evaluation of steel corrosion in RC, where the effect of steel corrosion and the integrity of the concrete structure can be assessed effectively. A complementary study of NDT methods for the investigation of corrosion is presented here. In this paper, acoustic emission (AE) effectively detects the corrosion of concrete structures at an early stage. The capability of the AE technique to detect corrosion occurring in real-time makes it a strong candidate for serving as an efficient NDT method, giving it an advantage over other NDT methods. PMID:26251904

  19. Introducing passive acoustic filter in acoustic based condition monitoring: Motor bike piston-bore fault identification

    NASA Astrophysics Data System (ADS)

    Jena, D. P.; Panigrahi, S. N.

    2016-03-01

    Requirement of designing a sophisticated digital band-pass filter in acoustic based condition monitoring has been eliminated by introducing a passive acoustic filter in the present work. So far, no one has attempted to explore the possibility of implementing passive acoustic filters in acoustic based condition monitoring as a pre-conditioner. In order to enhance the acoustic based condition monitoring, a passive acoustic band-pass filter has been designed and deployed. Towards achieving an efficient band-pass acoustic filter, a generalized design methodology has been proposed to design and optimize the desired acoustic filter using multiple filter components in series. An appropriate objective function has been identified for genetic algorithm (GA) based optimization technique with multiple design constraints. In addition, the sturdiness of the proposed method has been demonstrated in designing a band-pass filter by using an n-branch Quincke tube, a high pass filter and multiple Helmholtz resonators. The performance of the designed acoustic band-pass filter has been shown by investigating the piston-bore defect of a motor-bike using engine noise signature. On the introducing a passive acoustic filter in acoustic based condition monitoring reveals the enhancement in machine learning based fault identification practice significantly. This is also a first attempt of its own kind.

  20. Acoustic transducer for nuclear reactor monitoring

    DOEpatents

    Ahlgren, Frederic F.; Scott, Paul F.

    1977-01-01

    A transducer to monitor a parameter and produce an acoustic signal from which the monitored parameter can be recovered. The transducer comprises a modified Galton whistle which emits a narrow band acoustic signal having a frequency dependent upon the parameter being monitored, such as the temperature of the cooling media of a nuclear reactor. Multiple locations within a reactor are monitored simultaneously by a remote acoustic receiver by providing a plurality of transducers each designed so that the acoustic signal it emits has a frequency distinct from the frequencies of signals emitted by the other transducers, whereby each signal can be unambiguously related to a particular transducer.

  1. Acoustically based fetal heart rate monitor

    NASA Technical Reports Server (NTRS)

    Baker, Donald A.; Zuckerwar, Allan J.

    1991-01-01

    The acoustically based fetal heart rate monitor permits an expectant mother to perform the fetal Non-Stress Test in her home. The potential market would include the one million U.S. pregnancies per year requiring this type of prenatal surveillance. The monitor uses polyvinylidene fluoride (PVF2) piezoelectric polymer film for the acoustic sensors, which are mounted in a seven-element array on a cummerbund. Evaluation of the sensor ouput signals utilizes a digital signal processor, which performs a linear prediction routine in real time. Clinical tests reveal that the acoustically based monitor provides Non-Stress Test records which are comparable to those obtained with a commercial ultrasonic transducer.

  2. Air Coupled Acoustic Thermography (acat) Inspection Technique

    NASA Astrophysics Data System (ADS)

    Zalameda, J. N.; Winfree, W. P.; Yost, W. T.

    2008-02-01

    The scope of this effort is to determine the viability of a new heating technique using a noncontact acoustic excitation source. Because of low coupling between air and the structure, a synchronous detection method is employed. Any reduction in the out of plane stiffness improves the acoustic coupling efficiency and as a result, defective areas have an increase in temperature relative to the surrounding area. Hence a new measurement system, based on air-coupled acoustic energy and synchronous detection is presented. An analytical model of a clamped circular plate is given, experimentally tested, and verified. Repeatability confirms the technique with a measurement uncertainty of +/-6.2 percent. The range of frequencies used was 800-2,000 Hertz. Acoustic excitation and consequent thermal detection of flaws in a helicopter blade is examined and results indicate that air coupled acoustic excitation enables the detection of core damage in sandwich honeycomb structures.

  3. Air Coupled Acoustic Thermography (ACAT) Inspection Technique

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph; Winfree, William P.; Yost, William T.

    2007-01-01

    The scope of this effort is to determine the viability of a new heating technique using a noncontact acoustic excitation source. Because of low coupling between air and the structure, a synchronous detection method is employed. Any reduction in the out of plane stiffness improves the acoustic coupling efficiency and as a result, defective areas have an increase in temperature relative to the surrounding area. Hence a new measurement system, based on air-coupled acoustic energy and synchronous detection is presented. An analytical model of a clamped circular plate is given, experimentally tested, and verified. Repeatability confirms the technique with a measurement uncertainty of plus or minus 6.2 percent. The range of frequencies used was 800-2,000 Hertz. Acoustic excitation and consequent thermal detection of flaws in a helicopter blade is examined and results indicate that air coupled acoustic excitation enables the detection of core damage in sandwich honeycomb structures.

  4. Acoustic Location of Lightning Using Interferometric Techniques

    NASA Astrophysics Data System (ADS)

    Erives, H.; Arechiga, R. O.; Stock, M.; Lapierre, J. L.; Edens, H. E.; Stringer, A.; Rison, W.; Thomas, R. J.

    2013-12-01

    Acoustic arrays have been used to accurately locate thunder sources in lightning flashes. The acoustic arrays located around the Magdalena mountains of central New Mexico produce locations which compare quite well with source locations provided by the New Mexico Tech Lightning Mapping Array. These arrays utilize 3 outer microphones surrounding a 4th microphone located at the center, The location is computed by band-passing the signal to remove noise, and then computing the cross correlating the outer 3 microphones with respect the center reference microphone. While this method works very well, it works best on signals with high signal to noise ratios; weaker signals are not as well located. Therefore, methods are being explored to improve the location accuracy and detection efficiency of the acoustic location systems. The signal received by acoustic arrays is strikingly similar to th signal received by radio frequency interferometers. Both acoustic location systems and radio frequency interferometers make coherent measurements of a signal arriving at a number of closely spaced antennas. And both acoustic and interferometric systems then correlate these signals between pairs of receivers to determine the direction to the source of the received signal. The primary difference between the two systems is the velocity of propagation of the emission, which is much slower for sound. Therefore, the same frequency based techniques that have been used quite successfully with radio interferometers should be applicable to acoustic based measurements as well. The results presented here are comparisons between the location results obtained with current cross correlation method and techniques developed for radio frequency interferometers applied to acoustic signals. The data were obtained during the summer 2013 storm season using multiple arrays sensitive to both infrasonic frequency and audio frequency acoustic emissions from lightning. Preliminary results show that

  5. Intraoperative neuromonitoring techniques in the surgical management of acoustic neuromas.

    PubMed

    Oh, Taemin; Nagasawa, Daniel T; Fong, Brendan M; Trang, Andy; Gopen, Quinton; Parsa, Andrew T; Yang, Isaac

    2012-09-01

    Unfavorable outcomes such as facial paralysis and deafness were once unfortunate probable complications following resection of acoustic neuromas. However, the implementation of intraoperative neuromonitoring during acoustic neuroma surgery has demonstrated placing more emphasis on quality of life and preserving neurological function. A modern review demonstrates a great degree of recent success in this regard. In facial nerve monitoring, the use of modern electromyography along with improvements in microneurosurgery has significantly improved preservation. Recent studies have evaluated the use of video monitoring as an adjunctive tool to further improve outcomes for patients undergoing surgery. Vestibulocochlear nerve monitoring has also been extensively studied, with the most popular techniques including brainstem auditory evoked potential monitoring, electrocochleography, and direct compound nerve action potential monitoring. Among them, direct recording remains the most promising and preferred monitoring method for functional acoustic preservation. However, when compared with postoperative facial nerve function, the hearing preservation is only maintained at a lower rate. Here, the authors analyze the major intraoperative neuromonitoring techniques available for acoustic neuroma resection. PMID:22937857

  6. Development of hydroacoustical techniques for the monitoring and classification of benthic habitats in Puck Bay: Modeling of acoustic waves scattering by seagrass

    NASA Astrophysics Data System (ADS)

    Raczkowska, A.; Gorska, N.

    2012-12-01

    Puck Bay is an area of high species biodiversity belonging to the Coastal Landscape Park of Baltic Sea Protected Areas (BSPA) and is also included in the list of the World Wide Fund for Nature (WWF) and covered by the protection program "Natura 2000". The underwater meadows of the Puck Bay are important for Europe's natural habitats due to their role in enhancing the productivity of marine ecosystems and providing shelter and optimal feeding conditions for many marine organisms. One of the dominant species comprising the underwater meadows of the Southern Baltic Sea is the seagrass Zostera marina. The spatial extent of underwater seagrass meadows is altered by pollution and eutrophication; therefore, to properly manage the area one must monitor its ecological state. Remote acoustic methods are useful tools for the monitoring of benthic habitats in many marine areas because they are non-invasive and allow researchers to obtain data from a large area in a short period of time. Currently there is a need to apply these methods in the Baltic Sea. Here we present an analysis of the mechanism of scattering of acoustic waves on seagrass in the Southern Baltic Sea based on the numerical modeling of acoustic wave scattering by the biological tissues of plants. The study was conducted by adapting a model developed on the basis of DWBA (Distorted Wave Born Approximation) developed by Stanton and Chu (2005) for fluid-like objects, including the characteristics of the Southern Baltic seagrass. Input data for the model, including the morphometry of seagrass leaves, their angle of inclination and the density plant cover, was obtained through the analysis of biological materials collected in the Puck Bay in the framework of a research project financed by the Polish Government (Development of hydroacoustic methods for studies of underwater meadows of Puck Bay, 6P04E 051 20). On the basis of the developed model, we have analyzed the dependence of the target strength of a single

  7. Surface acoustic wave dust deposition monitor

    DOEpatents

    Fasching, G.E.; Smith, N.S. Jr.

    1988-02-12

    A system is disclosed for using the attenuation of surface acoustic waves to monitor real time dust deposition rates on surfaces. The system includes a signal generator, a tone-burst generator/amplifier connected to a transmitting transducer for converting electrical signals into acoustic waves. These waves are transmitted through a path defining means adjacent to a layer of dust and then, in turn, transmitted to a receiving transducer for changing the attenuated acoustic wave to electrical signals. The signals representing the attenuated acoustic waves may be amplified and used in a means for analyzing the output signals to produce an output indicative of the dust deposition rates and/or values of dust in the layer. 8 figs.

  8. Swept-frequency acoustic interferometry technique for noninvasive chemical diagnostics

    SciTech Connect

    Sinha, D.N.; Springer, K.N.; Han, Wei; Lizon, D.C.; Houlton, R.J.

    1997-02-01

    Swept-Frequency Acoustic Interferometry (SFAI) is a noninvasive fluid characterization technique currently being developed for chemical weapons treaty verification. The SFAI technique determines sound speed and sound attenuation in a fluid over a wide frequency range from outside a container (e.g., reactor vessel, tank, pipe, industrial containers etc.). From the frequency dependence of sound attenuation, fluid density can also be determined. These physical parameters. when combined together, can be used to identify a range of chemicals. This technique can be adapted for chemical diagnostic applications, particularly in process control where monitoring of acoustic properties of chemicals (liquids, mixtures, emulsions, suspensions, etc.) may provide appropriate feedback information. The SFAI theory is discussed and experimental techniques are presented. Examples of several novel applications of the SFAI technique are also presented.

  9. Acoustic-emission monitoring of steam turbines

    NASA Astrophysics Data System (ADS)

    Graham, L. J.; Randall, R. L.; Hong, C.

    1982-04-01

    A method for the on-line detection of crack growth in steam turbine rotors based on acoustic emission (AE) monitoring is discussed. A systematic study involving a number of tasks was performed to evaluate the potential for the detection and correct identification of crack growth AE signals during various turbine operating conditions. These included acoustic wave propagation and attenuation measurements, background noise characterization, laboratory rotor material tests, monitoring equipment optimization, dynamic stress analysis of the rotor under transient operation and on-line source location and signal characterization. No crack growth was detected during the monitoring periods but there was sufficient information from the combined tasks to estimate the flaw growth detectability during different operating conditions if it occurs. The experience also suggests that AE monitoring can be useful for diagnosis of other turbine problems such as blade rubbing, out-of-balance condition, bearing deterioration, lubricating oil contamination and perhaps boiler exfoliation and blade erosion.

  10. Acoustic (loudspeaker) facial electromyographic monitoring: Part 1. Evoked electromyographic activity during acoustic neuroma resection.

    PubMed

    Prass, R L; Lüders, H

    1986-09-01

    A modification of the technique of acoustic facial electromyographic (EMG) monitoring, involving the use of a bipolar wire electrode, was used to monitor facial EMG activity during 13 consecutive unselected acoustic neuroma resections. EMG activity was synchronously recorded on the audio channels of operative video tapes so that the patterns of evoked EMG activity could be analyzed in relation to specific intraoperative events. Despite a relatively wide variety of apparent eliciting mechanisms, evoked EMG activity occurred in only three general acoustic patterns; these were bursts, trains, and pulses. These respective patterns are described in detail and related to specific etiological mechanisms. The possible clinical significance of various patterns of evoked EMG activity is discussed.

  11. An acoustic mode measurement technique

    NASA Astrophysics Data System (ADS)

    Joppa, P. D.

    1984-10-01

    Turbomachinery noise propagates in aircraft jet engine ducts in a complicated manner. Measurement of this propagation is useful both to identify source mechanisms and to design efficient linings. A practical method of making these measurements has been developed, using linear arrays of equally spaced microphones mounted flush with the duct wall. Circumferential or axial arrays are analyzed by spatial Fourier transform, giving sound level as a function of spinning order or axial wavenumber respectively. Complex demodulation is used to acquire data in a modest bandwidth around a high frequency of interest. A joint NASA/Boeing test of the system used 32 microphones in a JT15D turbofan engine inlet. A 400-Hz bandwidth centered at blade passage frequency and at half blade passage frequency was studied. The theoretically predicted modes were clearly seen at blade passage frequency; broadband noise at half blade passage frequency was biased towards modes corotating with the fan. Interference between similar modes was not a significant problem. A lining design study indicated a 15 percent improvement in lining efficiency was possible when mode data were used, for this particular engine. The technique has proven reliable and useful for source diagnostics and lining design.

  12. Monitoring of acoustic emission activity using thin wafer piezoelectric sensors

    NASA Astrophysics Data System (ADS)

    Trujillo, Blaine; Zagrai, Andrei; Meisner, Daniel; Momeni, Sepand

    2014-03-01

    Acoustic emission (AE) is a well-known technique for monitoring onset and propagation of material damage. The technique has demonstrated utility in assessment of metallic and composite materials in applications ranging from civil structures to aerospace vehicles. While over the course of few decades AE hardware has changed dramatically with the sensors experiencing little changes. A traditional acoustic emission sensor solution utilizes a thickness resonance of the internal piezoelectric element which, coupled with internal amplification circuit, results in relatively large sensor footprint. Thin wafer piezoelectric sensors are small and unobtrusive, but they have seen limited AE applications due to low signal-to-noise ratio and other operation difficulties. In this contribution, issues and possible solutions pertaining to the utility of thin wafer piezoelectrics as AE sensors are discussed. Results of AE monitoring of fatigue damage using thin wafer piezoelectric and conventional AE sensors are presented.

  13. Nonintrusive Monitoring and Control of Metallurgical Processes by Acoustic Measurements

    NASA Astrophysics Data System (ADS)

    Yu, Hao-Ling; Khajavi, Leili Tafaghodi; Barati, Mansoor

    2011-06-01

    The feasibility of developing a new online monitoring technique based on the characteristic acoustic response of gas bubbles in a liquid has been investigated. The method is intended to monitor the chemistry of the liquid through its relation to the bubble sound frequency. A low-temperature model consisting of water and alcohol mixtures was established, and the frequency of bubbles rising under varying concentrations of methanol was measured. It was shown that the frequency of the sound created by bubble pulsation varies with the percentage of alcohol in water. The frequency drops sharply with the increase in methanol content up to 20 wt pct, after which the decreases is gradual. Surface tension seems to be a critical liquid property affecting the sound frequency through its two-fold effects on the bubble size and the pulsation domain. The dependence between the frequency and the liquid composition suggests the feasibility of developing an acoustic-based technique for process control purposes.

  14. Monitoring damage growth in titanium matrix composites using acoustic emission

    NASA Technical Reports Server (NTRS)

    Bakuckas, J. G., Jr.; Prosser, W. H.; Johnson, W. S.

    1993-01-01

    The application of the acoustic emission (AE) technique to locate and monitor damage growth in titanium matrix composites (TMC) was investigated. Damage growth was studied using several optical techniques including a long focal length, high magnification microscope system with image acquisition capabilities. Fracture surface examinations were conducted using a scanning electron microscope (SEM). The AE technique was used to locate damage based on the arrival times of AE events between two sensors. Using model specimens exhibiting a dominant failure mechanism, correlations were established between the observed damage growth mechanisms and the AE results in terms of the events amplitude. These correlations were used to monitor the damage growth process in laminates exhibiting multiple modes of damage. Results revealed that the AE technique is a viable and effective tool to monitor damage growth in TMC.

  15. Damage Detection and Analysis in CFRPs Using Acoustic Emission Technique

    NASA Astrophysics Data System (ADS)

    Whitlow, Travis Laron

    Real time monitoring of damage is an important aspect of life management of critical structures. Acoustic emission (AE) techniques allow for measurement and assessment of damage in real time. Acoustic emission parameters such as signal amplitude and duration were monitored during the loading sequences. Criteria that can indicate the onset of critical damage to the structure were developed. Tracking the damage as it happens gives a better analysis of the failure evolution that will allow for a more accurate determination of structural life. The main challenge is distinguishing between legitimate damage signals and "false positives" which are unrelated to damage growth. Such false positives can be related to electrical noise, friction, or mechanical vibrations. This research focuses on monitoring signals of damage growth in carbon fiber reinforced polymers (CFRPs) and separating the relevant signals from the false ones. In this Dissertation, acoustic emission signals from CFRP specimens were experimentally recorded and analyzed. The objectives of this work are: (1) perform static and fatigue loading of CFRP composite specimens and measure the associated AE signals, (2) accurately determine the AE parameters (energy, frequency, duration, etc.) of signals generated during failure of such specimens, (3) use fiber optic sensors to monitor the strain distribution of the damage zone and relate these changes in strain measurements to AE data.

  16. Acoustic emission monitoring of wind turbine blades

    NASA Astrophysics Data System (ADS)

    Van Dam, Jeremy; Bond, Leonard J.

    2015-03-01

    Damage to wind turbine blades can, if left uncorrected, evolve into catastrophic failures resulting in high costs and significant losses for the operator. Detection of damage, especially in real time, has the potential to mitigate the losses associated with such catastrophic failure. To address this need various forms of online monitoring are being investigated, including acoustic emission detection. In this paper, pencil lead breaks are used as a standard reference source and tests are performed on unidirectional glass-fiber-reinforced-polymer plates. The mechanical pencil break is used to simulate an acoustic emission (AE) that generates elastic waves in the plate. Piezoelectric sensors and a data acquisition system are used to detect and record the signals. The expected dispersion curves generated for Lamb waves in plates are calculated, and the Gabor wavelet transform is used to provide dispersion curves based on experimental data. AE sources using an aluminum plate are used as a reference case for the experimental system and data processing validation. The analysis of the composite material provides information concerning the wave speed, modes, and attenuation of the waveform, which can be used to estimate maximum AE event - receiver separation, in a particular geometry and materials combination. The foundational data provided in this paper help to guide improvements in online structural health monitoring of wind turbine blades using acoustic emission.

  17. Techniques in audio and acoustic measurement

    NASA Astrophysics Data System (ADS)

    Kite, Thomas D.

    2003-10-01

    Measurement of acoustic devices and spaces is commonly performed with time-delay spectrometry (TDS) or maximum length sequence (MLS) analysis. Both techniques allow an impulse response to be measured with a signal-to-noise ratio (SNR) that can be traded off against the measurement time. However, TDS suffers from long measurement times because of its linear sweep, while MLS suffers from the corruption of the impulse response by distortion. Recently a logarithmic sweep-based method has been devised which offers high SNR, short measurement times, and the ability to separate the linear impulse response from the impulse responses of distortion products. The applicability of these methods to audio and acoustic measurement will be compared.

  18. Continuous Surveillance Technique for Flow Accelerated Corrosion of Pipe Wall Using Electromagnetic Acoustic Transducer

    NASA Astrophysics Data System (ADS)

    Kojima, F.; Kosaka, D.; Umetani, K.

    2011-06-01

    In this paper, we propose a on-line monitoring technique using electromagnetic acoustic transducer (EMAT). In the series of laboratory experiments, carbon steel pipes were used and each sample was fabricated to simulate FAC. Electromagnetic acoustic resonance method (EMAR) is successfully tested for pipe wall thickness measurements. The validity and the feasibility of our method are also demonstrated through the laboratory experiments.

  19. Multipurpose Acoustic Sensor for Downhole Fluid Monitoring

    SciTech Connect

    Pantea, Cristian

    2012-05-04

    The projects objectives and purpose are to: (1) development a multipurpose acoustic sensor for downhole fluid monitoring in Enhanced Geothermal Systems (EGS) reservoirs over typical ranges of pressures and temperatures and demonstrate its capabilities and performance for different EGS systems; (2) determine in real-time and in a single sensor package several parameters - temperature, pressure, fluid flow and fluid properties; (3) needed in nearly every phase of an EGS project, including Testing of Injection and Production Wells, Reservoir Validation, Inter-well Connectivity, Reservoir Scale Up and Reservoir Sustainability. (4) Current sensors are limited to operating at lower temperatures, but the need is for logging at high temperatures. The present project deals with the development of a novel acoustic-based sensor that can work at temperatures up to 374 C, in inhospitable environments.

  20. Acoustic monitoring of power-plant valves

    NASA Astrophysics Data System (ADS)

    Allen, J. W.; Hartman, W. F.; Robinson, J. C.

    1982-06-01

    Advanced surveillance diagnostics were applied to key nuclear power plant valves to improve the availability of the power plant. Two types of valves were monitored: BWR three-stage, pilot-operated safety/relief valves and PWR feedwater control valves. Excessive leakage across the pilot-disc seat in BWR safety/relief valves can cause the second-stage pressure to reach the critical value that activates the valve, even though the set pressure was not exceeded. Acoustic emissions created by the leak noise were monitored and calibrated to indicate incipient activation of the safety/relief valve. Hydrodynamic, vibration, control and process signals from PWR feedwater control valves were monitored by a mini-computer based surveillance system. On-line analysis of these signals coupled with earlier analytic modelling identified: (1) cavitation, (2) changes in steam packaging tightness, (3) valve stem torquing, (4) transducer oscillations, and (5) peak vibration levels during power transients.

  1. Acoustic monitoring of power plant valves

    NASA Astrophysics Data System (ADS)

    Allen, J. W.; Hartman, W. F.; Robinson, J. C.

    1982-06-01

    Advanced surveillance diagnostics were applied to key nuclear power plant valves to improve the availability of the power plant. Two types of valves were monitored: boiling water reactor (BWR) three-stage, pilot-operated safety/relief valves and pressurized water reactor (PWR) feedwater control valves. Excessive leakage across the pilot-disc seat in BWR safety/relief valves can cause the second-stage pressure to reach the critical value that activates the valve, even though the set pressure was not exceeded. Acoustic emission created by the leak noise were monitored and calibrated to indicate incipient activation of the safety/relief valve. Hydrodynamic, vibration, control and process signals frm PWR feedwater control valves were monitored by a mini-computer based surveillance system.

  2. Active Acoustic Monitoring of Aquatic Life.

    PubMed

    Stein, Peter J; Edson, Patrick

    2016-01-01

    Active acoustic monitoring (AAM) can be used to study the behavioral response of marine life and to mitigate harm during high-danger anthropogenic activities. This has been done in fish studies for many decades, and there are now case studies in which AAM has been used for marine mammal monitoring as well. This includes monitoring where the ranges, AAM frequency of operation, and species are such that the AAM operation is completely outside the hearing range of the animals. However, it also includes AAM operations within the hearing range of marine life, although this does not necessarily that imply AAM is not a suitable tool. It is just not always possible to have a sufficient detection and tracking range and operate at a frequency outside the marine life hearing range. Likely, the best and most important application of AAM is when the anthropogenic activity to be conducted is temporary and presents a clear danger to aquatic life. PMID:26611075

  3. Active Acoustic Monitoring of Aquatic Life.

    PubMed

    Stein, Peter J; Edson, Patrick

    2016-01-01

    Active acoustic monitoring (AAM) can be used to study the behavioral response of marine life and to mitigate harm during high-danger anthropogenic activities. This has been done in fish studies for many decades, and there are now case studies in which AAM has been used for marine mammal monitoring as well. This includes monitoring where the ranges, AAM frequency of operation, and species are such that the AAM operation is completely outside the hearing range of the animals. However, it also includes AAM operations within the hearing range of marine life, although this does not necessarily that imply AAM is not a suitable tool. It is just not always possible to have a sufficient detection and tracking range and operate at a frequency outside the marine life hearing range. Likely, the best and most important application of AAM is when the anthropogenic activity to be conducted is temporary and presents a clear danger to aquatic life.

  4. Acoustic Flow Monitor System - User Manual

    USGS Publications Warehouse

    LaHusen, Richard

    2005-01-01

    INTRODUCTION The Acoustic Flow Monitor (AFM) is a portable system that was designed by the U.S. Geological Survey Cascades Volcano Observatory to detect and monitor debris flows associated with volcanoes. It has been successfully used internationally as part of real-time warning systems in valleys threatened by such flows (Brantley, 1990; Marcial and others, 1996; Lavigne and others, 2000). The AFM system has also been proven to be an effective tool for monitoring some non-volcanic debris flows. This manual is intended to serve as a basic guide for the installation, testing, and maintenance of AFM systems. An overview of how the system works, as well as instructions for installation and guidelines for testing, is included. Interpretation of data is not covered in this manual; rather, the user should refer to the references provided for published examples of AFM data.

  5. Detection of respiratory compromise by acoustic monitoring, capnography, and brain function monitoring during monitored anesthesia care.

    PubMed

    Tanaka, Pedro P; Tanaka, Maria; Drover, David R

    2014-12-01

    Episodes of apnea in sedated patients represent a risk of respiratory compromise. We hypothesized that acoustic monitoring would be equivalent to capnography for detection of respiratory pauses, with fewer false alarms. In addition, we hypothesized that the patient state index (PSI) would be correlated with the frequency of respiratory pauses and therefore could provide information about the risk of apnea during sedation. Patients undergoing sedation for surgical procedures were monitored for respiration rate using acoustic monitoring and capnography and for depth of sedation using the PSI. A clinician blinded to the acoustic and sedation monitor observed the capnograph and patient to assess sedation and episodes of apnea. Another clinician retrospectively reviewed the capnography and acoustic waveform and sound files to identify true positive and false positive respiratory pauses by each method (reference method). Sensitivity, specificity, and likelihood ratio for detection of respiratory pause was calculated for acoustic monitoring and capnography. The correlation of PSI with respiratory pause events was determined. For the 51 respiratory pauses validated by retrospective analysis, the sensitivity, specificity, and likelihood ratio positive for detection were 16, 96 %, and 3.5 for clinician observation; 88, 7 %, and 1.0 for capnography; and 55, 87 %, and 4.1 for acoustic monitoring. There was no correlation between PSI and respiratory pause events. Acoustic monitoring had the highest likelihood ratio positive for detection of respiratory pause events compared with capnography and clinician observation and, therefore, may provide the best method for respiration rate monitoring during these procedures. PMID:24420342

  6. Acoustic module of the Acquabona (Italy) debris flow monitoring system

    NASA Astrophysics Data System (ADS)

    Galgaro, A.; Tecca, P. R.; Genevois, R.; Deganutti, A. M.

    2005-02-01

    Monitoring of debris flows aimed to the assessment of their physical parameters is very important both for theoretical and practical purposes. Peak discharge and total volume of debris flows are crucial for designing effective countermeasures in many populated mountain areas where losses of lives and property damage could be avoided. This study quantifies the relationship between flow depth, acoustic amplitude of debris flow induced ground vibrations and front velocity in the experimental catchment of Acquabona, Eastern Dolomites, Italy. The analysis of data brought about the results described in the following. Debris flow depth and amplitude of the flow-induced ground vibrations show a good positive correlation. Estimation of both mean front velocity and peak discharge can be simply obtained monitoring the ground vibrations, through geophones installed close to the flow channel; the total volume of debris flow can be so directly estimated from the integral of the ground vibrations using a regression line. The application of acoustic technique to debris flow monitoring seems to be of the outmost relevance in risk reduction policies and in the correct management of the territory. Moreover this estimation is possible in other catchments producing debris flows of similar characteristics by means of their acoustic characterisation through quick and simple field tests (Standard Penetration Tests and seismic refraction surveys).

  7. Acoustic emission monitoring of HFIR vessel during hydrostatic testing

    SciTech Connect

    Friesel, M.A.; Dawson, J.F.

    1992-08-01

    This report discusses the results and conclusions reached from applying acoustic emission monitoring to surveillance of the High Flux Isotope Reactor vessel during pressure testing. The objective of the monitoring was to detect crack growth and/or fluid leakage should it occur during the pressure test. The report addresses the approach, acoustic emission instrumentation, installation, calibration, and test results.

  8. Fracture of human femur tissue monitored by acoustic emission sensors.

    PubMed

    Aggelis, Dimitrios G; Strantza, Maria; Louis, Olivia; Boulpaep, Frans; Polyzos, Demosthenes; van Hemelrijck, Danny

    2015-01-01

    The study describes the acoustic emission (AE) activity during human femur tissue fracture. The specimens were fractured in a bending-torsion loading pattern with concurrent monitoring by two AE sensors. The number of recorded signals correlates well with the applied load providing the onset of micro-fracture at approximately one sixth of the maximum load. Furthermore, waveform frequency content and rise time are related to the different modes of fracture (bending of femur neck or torsion of diaphysis). The importance of the study lies mainly in two disciplines. One is that, although femurs are typically subjects of surgical repair in humans, detailed monitoring of the fracture with AE will enrich the understanding of the process in ways that cannot be achieved using only the mechanical data. Additionally, from the point of view of monitoring techniques, applying sensors used for engineering materials and interpreting the obtained data pose additional difficulties due to the uniqueness of the bone structure.

  9. Fracture of Human Femur Tissue Monitored by Acoustic Emission Sensors

    PubMed Central

    Aggelis, Dimitrios. G.; Strantza, Maria; Louis, Olivia; Boulpaep, Frans; Polyzos, Demosthenes; van Hemelrijck, Danny

    2015-01-01

    The study describes the acoustic emission (AE) activity during human femur tissue fracture. The specimens were fractured in a bending-torsion loading pattern with concurrent monitoring by two AE sensors. The number of recorded signals correlates well with the applied load providing the onset of micro-fracture at approximately one sixth of the maximum load. Furthermore, waveform frequency content and rise time are related to the different modes of fracture (bending of femur neck or torsion of diaphysis). The importance of the study lies mainly in two disciplines. One is that, although femurs are typically subjects of surgical repair in humans, detailed monitoring of the fracture with AE will enrich the understanding of the process in ways that cannot be achieved using only the mechanical data. Additionally, from the point of view of monitoring techniques, applying sensors used for engineering materials and interpreting the obtained data pose additional difficulties due to the uniqueness of the bone structure. PMID:25763648

  10. Fracture of human femur tissue monitored by acoustic emission sensors.

    PubMed

    Aggelis, Dimitrios G; Strantza, Maria; Louis, Olivia; Boulpaep, Frans; Polyzos, Demosthenes; van Hemelrijck, Danny

    2015-01-01

    The study describes the acoustic emission (AE) activity during human femur tissue fracture. The specimens were fractured in a bending-torsion loading pattern with concurrent monitoring by two AE sensors. The number of recorded signals correlates well with the applied load providing the onset of micro-fracture at approximately one sixth of the maximum load. Furthermore, waveform frequency content and rise time are related to the different modes of fracture (bending of femur neck or torsion of diaphysis). The importance of the study lies mainly in two disciplines. One is that, although femurs are typically subjects of surgical repair in humans, detailed monitoring of the fracture with AE will enrich the understanding of the process in ways that cannot be achieved using only the mechanical data. Additionally, from the point of view of monitoring techniques, applying sensors used for engineering materials and interpreting the obtained data pose additional difficulties due to the uniqueness of the bone structure. PMID:25763648

  11. Acoustic Monitoring of the Arctic Ice Cap

    NASA Astrophysics Data System (ADS)

    Porter, D. L.; Goemmer, S. A.; Chayes, D. N.

    2012-12-01

    Introduction The monitoring of the Arctic Ice Cap is important economically, tactically, and strategically. In the scenario of ice cap retreat, new paths of commerce open, e.g. waterways from Northern Europe to the Far East. Where ship-going commerce is conducted, the U.S. Navy and U.S. Coast Guard have always stood guard and been prepared to assist from acts of nature and of man. It is imperative that in addition to measuring the ice from satellites, e.g. Icesat, that we have an ability to measure the ice extent, its thickness, and roughness. These parameters play an important part in the modeling of the ice and the processes that control its growth or shrinking and its thickness. The proposed system consists of three subsystems. The first subsystem is an acoustic source, the second is an array of geophones and the third is a system to supply energy and transmit the results back to the analysis laboratory. The subsystems are described below. We conclude with a plan on how to tackle this project and the payoff to the ice cap modeler and hence the users, i.e. commerce and defense. System Two historically tested methods to generate a large amplitude multi-frequency sound source include explosives and air guns. A new method developed and tested by the University of Texas, ARL is a combustive Sound Source [Wilson, et al., 1995]. The combustive sound source is a submerged combustion chamber that is filled with the byproducts of the electrolysis of sea water, i.e. Hydrogen and Oxygen, an explosive mixture which is ignited via a spark. Thus, no additional compressors, gases, or explosives need to be transported to the Arctic to generate an acoustic pulse capable of the sediment and the ice. The second subsystem would be geophones capable of listening in the O(10 Hz) range and transmitting that data back to the laboratory. Thus two single arrays of geophones arranged orthogonal to each other with a range of 1000's of kilometers and a combustive sound source where the two

  12. Tritium monitoring techniques

    SciTech Connect

    DeVore, J.R.; Buckner, M.A.

    1996-05-01

    As part of their operations, the U.S. Navy is required to store or maintain operational nuclear weapons on ships and at shore facilities. Since these weapons contain tritium, there are safety implications relevant to the exposure of personnel to tritium. This is particularly important for shipboard operations since these types of environments can make low-level tritium detection difficult. Some of these ships have closed systems, which can result in exposure to tritium at levels that are below normally acceptable levels but could still cause radiation doses that are higher than necessary or could hamper ship operations. This report describes the state of the art in commercial tritium detection and monitoring and recommends approaches for low-level tritium monitoring in these environments.

  13. Multiplexing Technology for Acoustic Emission Monitoring of Aerospace Vehicles

    NASA Technical Reports Server (NTRS)

    Prosser, William; Percy, Daniel

    2003-01-01

    The initiation and propagation of damage mechanisms such as cracks and delaminations generate acoustic waves, which propagate through a structure. These waves can be detected and analyzed to provide the location and severity of damage as part of a structural health monitoring (SHM) system. This methodology of damage detection is commonly known as acoustic emission (AE) monitoring, and is widely used on a variety of applications on civil structures. AE has been widely considered for SHM of aerospace vehicles. Numerous successful ground and flight test demonstrations have been performed, which show the viability of the technology for damage monitoring in aerospace structures. However, one significant current limitation for application of AE techniques on aerospace vehicles is the large size, mass, and power requirements for the necessary monitoring instrumentation. To address this issue, a prototype multiplexing approach has been developed and demonstrated in this study, which reduces the amount of AE monitoring instrumentation required. Typical time division multiplexing techniques that are commonly used to monitor strain, pressure and temperature sensors are not applicable to AE monitoring because of the asynchronous and widely varying rates of AE signal occurrence. Thus, an event based multiplexing technique was developed. In the initial prototype circuit, inputs from eight sensors in a linear array were multiplexed into two data acquisition channels. The multiplexer rapidly switches, in less than one microsecond, allowing the signals from two sensors to be acquired by a digitizer. The two acquired signals are from the sensors on either side of the trigger sensor. This enables the capture of the first arrival of the waves, which cannot be accomplished with the signal from the trigger sensor. The propagation delay to the slightly more distant neighboring sensors makes this possible. The arrival time from this first arrival provides a more accurate source location

  14. Guided wave acoustic monitoring of corrosion in recovery boiler tubing

    SciTech Connect

    Quarry, M J; Chinn, D J

    2004-02-19

    Corrosion of tubing used in black-liquor recovery boilers is a major concern in all pulp and paper mills. Extensive corrosion in recovery boiler tubes can result in a significant safety and environmental hazard. Considerable plant resources are expended to inspect recovery boiler tubing. Currently, visual and ultrasonic inspections are primarily used during the annual maintenance shutdown to monitor corrosion rates and cracking of tubing. This Department of Energy, Office of Industrial Technologies project is developing guided acoustic waves for use on recovery boiler tubing. The feature of this acoustic technique is its cost-effectiveness in inspecting long lengths of tubes from a single inspection point. A piezoelectric or electromagnetic transducer induces guided waves into the tubes. The transducer detects fireside defects from the coldside or fireside of the tube. Cracking and thinning on recovery boiler tubes have been detected with this technique in both laboratory and field applications. This technique appears very promising for recovery boiler tube application, potentially expediting annual inspection of tube integrity.

  15. FRP/steel composite damage acoustic emission monitoring and analysis

    NASA Astrophysics Data System (ADS)

    Li, Dongsheng; Chen, Zhi

    2015-04-01

    FRP is a new material with good mechanical properties, such as high strength of extension, low density, good corrosion resistance and anti-fatigue. FRP and steel composite has gotten a wide range of applications in civil engineering because of its good performance. As the FRP/steel composite get more and more widely used, the monitor of its damage is also getting more important. To monitor this composite, acoustic emission (AE) is a good choice. In this study, we prepare four identical specimens to conduct our test. During the testing process, the AE character parameters and mechanics properties were obtained. Damaged properties of FRP/steel composite were analyzed through acoustic emission (AE) signals. By the growing trend of AE accumulated energy, the severity of the damage made on FRP/steel composite was estimated. The AE sentry function has been successfully used to study damage progression and fracture emerge release rate of composite laminates. This technique combines the cumulative AE energy with strain energy of the material rather than analyzes the AE information and mechanical separately.

  16. Using the Acoustic Emission Technique for Estimating Body Composition

    NASA Astrophysics Data System (ADS)

    González-Solís, J. L.; Sanchis-Sabater, A.; Sosa-Aquino, M.; Gutiérrez-Juárez, G.; Vargas-Luna, M.; Bernal-Alvarado, J.; Huerta-Franco, R.

    2003-09-01

    This work proposes a new technique for estimation of body composition by using acoustic emission. A simple apparatus for the acoustic emission is proposed.The estimation of the body composition is made by analyzing the correlation between a set of acoustic resonance and skinfold measurements. One device was designed to measure the position and width of the acoustic resonances and a caliper was used to measure the skinfolds. The results show the plausibility of application of the method to measurement the human body fat.

  17. Study on Acoustic Catheter of Boiler Tube Leakage Monitoring Systems

    NASA Astrophysics Data System (ADS)

    Lv, Yongxing; Feng, Qiang

    Boiler tube leakage is the major reason of affecting the safe operation of the unit now, there are 3 methods of the "four tube" leakage detection: Traditional method, filtering method and acoustic spectrum analysis, acoustic spectrum analysis is the common method, but this method have low sensitivity and the sensor damage easily. Therewith, designed the special acoustic catheter with acoustic resonance cavity type, proved by experiments, the acoustic catheter with acoustic resonance cavity type can enhance leakage sound, can accurately extract leakage signals, has high sensitivity, and can avoid the effect of sensor by fire and hot-gas when the furnace is in positive pressure situation, reduce the installation and maintenance costs of the boiler tube leakage monitor system.

  18. New Techniques of Acoustic Seabed Classification at Ocean Margins

    NASA Astrophysics Data System (ADS)

    BLONDEL, P.

    2001-12-01

    Ocean margins have become the focus of most current geophysical and environmental surveys, because of their economic, scientific and oceanographic significance. These surveys deliver increasingly larger volumes of data, acquired by many types of techniques and sensors. Despite its importance, most of this data is still interpreted visually and qualitatively by skilled interpreters. The problem is that human interpretation is time-consuming and difficult to standardise. In certain conditions, it can be also be subject to more or less systematic errors. Current research in data processing is shifting toward computer-based interpretation techniques, and in particular seafloor classification. This presentation will review the different notions and objectives of classification. This will be followed with a review of acoustic (mainly sonar) classification techniques, supplemented with actual examples from around the world. In particular, new techniques recently developed will be presented, such as multistatic or multi-aspect 3-D sonar imaging. They provide access to a new wealth of useful parameters, often at extremely high-resolution. Seabed classification, in general and at ocean margins in particular, is fast becoming a major tool in seafloor surveying and monitoring,particularly with the development and increasing use of ROVs and autonomous platforms.

  19. Techniques for Primary Acoustic Thermometry to 800 K

    NASA Astrophysics Data System (ADS)

    Ripple, D. C.; Defibaugh, D. R.; Moldover, M. R.; Strouse, G. F.

    2003-09-01

    The NIST Primary Acoustic Thermometer will measure the difference between the International Temperature Scale of 1990 and the Kelvin Thermodynamic Scale throughout the range 273 K to 800 K with uncertainties of only a few millikelvins. The acoustic thermometer determines the frequencies of the acoustic resonances of pure argon gas contained within a spherical cavity with uncertainties approaching one part in 106. To achieve this small uncertainty at these elevated temperatures we developed new acoustic transducers and new techniques for the maintenance of gas purity and for temperature control. The new electro-acoustic transducers are based on the capacitance between a flexible silicon wafer and a rigid backing plate. Without the damping usually provided by polymers, mechanical vibrations caused unstable, spurious acoustic signals. We describe our techniques for suppression of these vibrations. Our acoustic thermometer allows the argon to be continuously flushed through the resonator, thereby preventing the build up of hydrogen that evolves from the stainless-steel resonator. We describe how the argon pressure is stabilized while flushing. The argon exiting from the resonator is analyzed with a customized gas chromatograph. Because the acoustic resonator was so large—it has an outer diameter of 20 cm—a sophisticated furnace, based on surrounding the resonator with three concentric aluminum shells, was designed to maintain thermal uniformity and stability of the resonator at a level of 1 mK. We describe the design, modeling, and operational characteristics of the furnace.

  20. An evaluation of acoustic seabed classification techniques for marine biotope monitoring over broad-scales (>1 km 2) and meso-scales (10 m 2-1 km 2)

    NASA Astrophysics Data System (ADS)

    van Rein, H.; Brown, C. J.; Quinn, R.; Breen, J.; Schoeman, D.

    2011-07-01

    Acoustic seabed classification is a useful tool for monitoring marine benthic habitats over broad-scales (>1 km 2) and meso-scales (10 m 2-1 km 2). Its utility in this context was evaluated using two approaches: by describing natural changes in the temporal distribution of marine biotopes across the broad-scale (4 km 2), and by attempting to detect specific experimentally-induced changes to kelp-dominated biotopes across the meso-scale (100 m 2). For the first approach, acoustic backscatter mosaics were constructed using sidescan sonar and multibeam echosounder data collected from Church Bay (Rathlin Island, Northern Ireland) in 1999, 2008 and 2009. The mosaics were manually segmented into acoustic facies, which were ground-truthed using a drop-video camera. Biotopes were classified from the video by multivariate exploratory analysis and cross-tabulated with the acoustic facies, showing a positive correlation. These results were integrated with bathymetric data to map the distribution of seven unique biotopes in Church Bay. Kappa analysis showed the biotope distribution was highly similar between the biotope maps, possibly due to the stability of bedforms shaped by the tidal regime around Rathlin Island. The greatest biotope change in this approach was represented by seasonal and annual changes in the growth of the seagrass, Zostera marina. In the second approach, sidescan sonar data were collected before and after the removal of 100 m 2 of kelp from three sites. Comparison of the data revealed no differences between the high-resolution backscatter imagery. It is concluded that acoustic seabed classification can be used to monitor change over broad- and meso-scales but not necessarily for all biotopes; its success depends on the type of acoustic system employed and the biological characteristics of the target biotope.

  1. Ecological Insights from Pelagic Habitats Acquired Using Active Acoustic Techniques

    NASA Astrophysics Data System (ADS)

    Benoit-Bird, Kelly J.; Lawson, Gareth L.

    2016-01-01

    Marine pelagic ecosystems present fascinating opportunities for ecological investigation but pose important methodological challenges for sampling. Active acoustic techniques involve producing sound and receiving signals from organisms and other water column sources, offering the benefit of high spatial and temporal resolution and, via integration into different platforms, the ability to make measurements spanning a range of spatial and temporal scales. As a consequence, a variety of questions concerning the ecology of pelagic systems lend themselves to active acoustics, ranging from organism-level investigations and physiological responses to the environment to ecosystem-level studies and climate. As technologies and data analysis methods have matured, the use of acoustics in ecological studies has grown rapidly. We explore the continued role of active acoustics in addressing questions concerning life in the ocean, highlight creative applications to key ecological themes ranging from physiology and behavior to biogeography and climate, and discuss emerging avenues where acoustics can help determine how pelagic ecosystems function.

  2. Ecological Insights from Pelagic Habitats Acquired Using Active Acoustic Techniques.

    PubMed

    Benoit-Bird, Kelly J; Lawson, Gareth L

    2016-01-01

    Marine pelagic ecosystems present fascinating opportunities for ecological investigation but pose important methodological challenges for sampling. Active acoustic techniques involve producing sound and receiving signals from organisms and other water column sources, offering the benefit of high spatial and temporal resolution and, via integration into different platforms, the ability to make measurements spanning a range of spatial and temporal scales. As a consequence, a variety of questions concerning the ecology of pelagic systems lend themselves to active acoustics, ranging from organism-level investigations and physiological responses to the environment to ecosystem-level studies and climate. As technologies and data analysis methods have matured, the use of acoustics in ecological studies has grown rapidly. We explore the continued role of active acoustics in addressing questions concerning life in the ocean, highlight creative applications to key ecological themes ranging from physiology and behavior to biogeography and climate, and discuss emerging avenues where acoustics can help determine how pelagic ecosystems function.

  3. Ecological Insights from Pelagic Habitats Acquired Using Active Acoustic Techniques.

    PubMed

    Benoit-Bird, Kelly J; Lawson, Gareth L

    2016-01-01

    Marine pelagic ecosystems present fascinating opportunities for ecological investigation but pose important methodological challenges for sampling. Active acoustic techniques involve producing sound and receiving signals from organisms and other water column sources, offering the benefit of high spatial and temporal resolution and, via integration into different platforms, the ability to make measurements spanning a range of spatial and temporal scales. As a consequence, a variety of questions concerning the ecology of pelagic systems lend themselves to active acoustics, ranging from organism-level investigations and physiological responses to the environment to ecosystem-level studies and climate. As technologies and data analysis methods have matured, the use of acoustics in ecological studies has grown rapidly. We explore the continued role of active acoustics in addressing questions concerning life in the ocean, highlight creative applications to key ecological themes ranging from physiology and behavior to biogeography and climate, and discuss emerging avenues where acoustics can help determine how pelagic ecosystems function. PMID:26515810

  4. Applications of swept-frequency acoustic interferometry technique in chemical diagnostics

    SciTech Connect

    Sinha, D.N.; Springer, K.; Lizon, D.; Hasse, R.

    1996-09-01

    Swept-Frequency Acoustic Interferometry (SFAI) is a noninvasive fluid characterization technique currently being developed for chemical weapons treaty verification. The SFAI technique determines sound speed and sound attenuation in a fluid over a wide frequency range completely noninvasively from outside a container (e.g., pipe, tank, reactor vessel, etc.,). These acoustic parameters, along with their frequency-dependence, can be used to identify various chemicals. This technique can be adapted for a range of chemical diagnostic applications, particularly, in process control where monitoring of acoustic properties of chemicals may provide appropriate feedback information. Both experimental data and theoretical modeling are presented. Examples of several novel applications of the SFAI technique are discussed.

  5. Passive acoustic monitoring of bed load for fluvial applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sediment transported as bed load in streams and rivers is notoriously difficult to monitor cheaply and accurately. Passive acoustic methods are relatively simple, inexpensive, and provide spatial integration along with high temporal resolution. In 1963 work began on monitoring emissions from par...

  6. Rotor acoustic monitoring system (RAMS): a fatigue crack detection system

    NASA Astrophysics Data System (ADS)

    Schoess, Jeffrey N.

    1996-05-01

    The Rotor Acoustic Monitoring System (RAMS) is an embedded structural health monitoring system to demonstrate the ability to detect rotor head fatigue cracks and provide early warning of propagating fatigue cracks in rotor components of Navy helicopters. The concept definition effort was performed to assess the feasibility of detecting rotor head fatigue cracks using bulk- wave wide-bandwidth acoustic emission technology. A wireless piezo-based transducer system is being designed to capture rotor fatigue data in real time and perform acoustic emission (AE) event detection, feature extraction, and classification. A flight test effort will be performed to characterize rotor acoustic background noise and flight environment characteristics. The long- term payoff of the RAMS technology includes structural integrity verification and leak detection for large industrial tanks, and nuclear plant cooling towers could be performed using the RAMS AE technology. A summary of the RAMS concept, bench-level AE fatigue testing, and results are presented.

  7. Continuous acoustic emission monitoring of reinforced concrete under accelerated corrosion

    NASA Astrophysics Data System (ADS)

    Di Benedetti, M.; Loreto, G.; Nanni, A.; Matta, F.; Gonzalez-Nunez, M. A.

    2011-04-01

    The development of techniques capable of evaluating deterioration of reinforced concrete (RC) structures is instrumental to the advancement of techniques for the structural health monitoring (SHM) and service life estimate for constructed facilities. One of the main causes leading to degradation of RC is the corrosion of the steel reinforcement. This process can be modeled phenomenologically, while laboratory tests aimed at studying durability responses are typically accelerated in order to provide useful results within a realistic period of time. To assess the condition of damage in RC, a number of nondestructive methods have been recently studied. Acoustic emission (AE) is emerging as a nondestructive tool to detect the onset and progression of deterioration mechanisms. In this paper, the development of accelerated corrosion and continuous AE monitoring test set-up for RC specimens are presented. Relevant information are provided with regard to the characteristics of the corrosion circuit, continuous measurement and acquisition of corrosion potential, selection of AE sensors and AE parameter setting. The effectiveness of the setup in detecting and characterizing the initiation and progression of the corrosion phenomenon is discussed on the basis of preliminary results from small-scale, pre-cracked RC specimens, which are representative of areas near the clear cover in typical RC bridge members.

  8. Damage Source Identification of Reinforced Concrete Structure Using Acoustic Emission Technique

    PubMed Central

    Panjsetooni, Alireza; Bunnori, Norazura Muhamad; Vakili, Amir Hossein

    2013-01-01

    Acoustic emission (AE) technique is one of the nondestructive evaluation (NDE) techniques that have been considered as the prime candidate for structural health and damage monitoring in loaded structures. This technique was employed for investigation process of damage in reinforced concrete (RC) frame specimens. A number of reinforced concrete RC frames were tested under loading cycle and were simultaneously monitored using AE. The AE test data were analyzed using the AE source location analysis method. The results showed that AE technique is suitable to identify the sources location of damage in RC structures. PMID:23997681

  9. Thick-film acoustic emission sensors for use in structurally integrated condition-monitoring applications.

    PubMed

    Pickwell, Andrew J; Dorey, Robert A; Mba, David

    2011-09-01

    Monitoring the condition of complex engineering structures is an important aspect of modern engineering, eliminating unnecessary work and enabling planned maintenance, preventing failure. Acoustic emissions (AE) testing is one method of implementing continuous nondestructive structural health monitoring. A novel thick-film (17.6 μm) AE sensor is presented. Lead zirconate titanate thick films were fabricated using a powder/sol composite ink deposition technique and mechanically patterned to form a discrete thick-film piezoelectric AE sensor. The thick-film sensor was benchmarked against a commercial AE device and was found to exhibit comparable responses to simulated acoustic emissions.

  10. OPERATING PROCEDURE FOR THE PORTABLE ACOUSTIC MONITORING PACKAGE (PAMP)

    SciTech Connect

    John L. Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Patrick Browning

    2004-08-29

    The Portable Acoustic Monitoring Package (PAMP) has been designed to record and monitor acoustic signals in high-pressure natural gas (NG) transmission lines. Of particular interest are the three acoustic signals associated with a pipeline fracture. The system is portable (less than 30 lbm) and can be used at all line pressures up to 1000 psig. The PAMP requires a shut-off valve equipped 1/2 inch NPT access port in the pipeline. It is fully functional over the typical pressure range found in the natural gas transmission pipelines in the West Virginia, Virginia, Pennsylvania, and Ohio areas. With the use of the PAMP, a full spectrum of acoustic signals can be recorded and defined in terms of acoustic energy in decibels. To detect natural gas pipeline infringements and leaks, the acoustic energy generated inside the line is monitored with a sensitive pressure-equalized microphone and a step function type {Delta}p transducer. The assembly is mounted on a 1000 psig pipe fitting-tree called the PAMP. The electronics required to record, store and analyze the data are described within this report in the format of an operating manual.

  11. Acoustic (loudspeaker) facial EMG monitoring: II. Use of evoked EMG activity during acoustic neuroma resection.

    PubMed

    Prass, R L; Kinney, S E; Hardy, R W; Hahn, J F; Lüders, H

    1987-12-01

    Facial electromyographic (EMG) activity was continuously monitored via loudspeaker during eleven translabyrinthine and nine suboccipital consecutive unselected acoustic neuroma resections. Ipsilateral facial EMG activity was synchronously recorded on the audio channels of operative videotapes, which were retrospectively reviewed in order to allow detailed evaluation of the potential benefit of various acoustic EMG patterns in the performance of specific aspects of acoustic neuroma resection. The use of evoked facial EMG activity was classified and described. Direct local mechanical (surgical) stimulation and direct electrical stimulation were of benefit in the localization and/or delineation of the facial nerve contour. Burst and train acoustic patterns of EMG activity appeared to indicate surgical trauma to the facial nerve that would not have been appreciated otherwise. Early results of postoperative facial function of monitored patients are presented, and the possible value of burst and train acoustic EMG activity patterns in the intraoperative assessment of facial nerve function is discussed. Acoustic facial EMG monitoring appears to provide a potentially powerful surgical tool for delineation of the facial nerve contour, the ongoing use of which may lead to continued improvement in facial nerve function preservation through modification of dissection strategy.

  12. Microwave de-embedding techniques applied to acoustics.

    PubMed

    Jackson, Charles M

    2005-07-01

    This paper describes the use of the microwave techniques of time domain reflectometry (TDR) and de-embedding in an acoustical application. Two methods of calibrating the reflectometer are presented to evaluate the consistency of the method. Measured and modeled S-parameters of woodwind instruments are presented. The raw measured data is de-embedded to obtain an accurate measurement. The acoustic TDR setup is described. PMID:16212248

  13. Monitoring deep-ocean temperatures using acoustic ambient noise

    NASA Astrophysics Data System (ADS)

    Woolfe, Katherine F.; Lani, Shane; Sabra, Karim G.; Kuperman, W. A.

    2015-04-01

    Measuring temperature changes of the deep oceans, important for determining the oceanic heat content and its impact on the Earth's climate evolution, is typically done using free-drifting profiling oceanographic floats with limited global coverage. Acoustic thermometry provides an alternative and complementary remote sensing methodology for monitoring fine temperature variations of the deep ocean over long distances between a few underwater sources and receivers. We demonstrate a simpler, totally passive (i.e., without deploying any active sources) modality for acoustic thermometry of the deep oceans (for depths of ~ 500-1500 m), using only ambient noise recorded by two existing hydroacoustic stations of the International Monitoring System. We suggest that passive acoustic thermometry could improve global monitoring of deep-ocean temperature variations through implementation using a global network of hydrophone arrays.

  14. Techniques for classifying acoustic resonant spectra

    SciTech Connect

    Roberts, R.S.; Lewis, P.S.; Chen, J.T.; Vela, O.A.

    1995-12-31

    A second-generation nondestructive evaluation (NDE) system that discriminates between different types of chemical munitions is under development. The NDE system extracts features from the acoustic spectra of known munitions, builds templates from these features, and performs classification by comparing features extracted from an unknown munition to a template library. Improvements over first-generation feature extraction template construction and classification algorithms are reported. Results are presented on the performance of the system and a large data set collected from surrogate-filled munitions.

  15. Monitoring the Ocean Acoustic Environment: A Model-Based Detection Approach

    SciTech Connect

    Candy, J.V.; Sullivan, E.J.

    2000-03-13

    A model-based approach is applied in the development of a processor designed to passively monitor an ocean acoustic environment along with its associated variations. The technique employs an adaptive, model-based processor embedded in a sequential likelihood detection scheme. The trade-off between state-based and innovations-based monitor designs is discussed, conceptually. The underlying theory for the innovations-based design is briefly developed and applied to a simulated data set.

  16. Early corrosion monitoring of prestressed concrete piles using acoustic emission

    NASA Astrophysics Data System (ADS)

    Vélez, William; Matta, Fabio; Ziehl, Paul H.

    2013-04-01

    The depassivation and corrosion of bonded prestressing steel strands in concrete bridge members may lead to major damage or collapse before visual inspections uncover evident signs of damage, and well before the end of the design life. Recognizing corrosion in its early stage is desirable to plan and prioritize remediation strategies. The Acoustic Emission (AE) technique is a rational means to develop structural health monitoring and prognosis systems for the early detection and location of corrosion in concrete. Compelling features are the sensitivity to events related to micro- and macrodamage, non-intrusiveness, and suitability for remote and wireless applications. There is little understanding of the correlation between AE and the morphology and extent of early damage on the steel surface. In this paper, the evidence collected from prestressed concrete (PC) specimens that are exposed to salt water is discussed vis-à-vis AE data from continuous monitoring. The specimens consist of PC strips that are subjected to wet/dry salt water cycles, representing portions of bridge piles that are exposed to tidal action. Evidence collected from the specimens includes: (a) values of half-cell potential and linear polarization resistance to recognize active corrosion in its early stage; and (b) scanning electron microscopy micrographs of steel areas from two specimens that were decommissioned once the electrochemical measurements indicated a high probability of active corrosion. These results are used to evaluate the AE activity resulting from early corrosion.

  17. Feasibility of a phased acoustic array for monitoring acoustic signatures from meshing gear teeth.

    PubMed

    Hood, Adrian A; Pines, Darryll J

    2002-12-01

    This paper investigates the feasibility of sensing damage emanating from rotating drivetrain elements such as bearings, gear teeth, and drive shafts via airborne paths. A planar phased acoustic array is evaluated as a potential fault detection scheme for detecting spatially filtered acoustic signatures radiating from gearbox components. Specifically, the use of beam focusing and steering to monitor individual tooth mesh dynamics is analyzed taking into consideration the constraints of the array/gearbox geometry and the spectral content of typical gear noise. Experimental results for a linear array are presented to illustrate the concepts of adaptive beam steering and spatial acoustic filtering. This feasibility study indicates that the planar array can be used to track the acoustic signatures at higher harmonics of the gear mesh frequency.

  18. Development of a portable passive-acoustic bedload monitoring system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A hydrophone-based passive acoustic bedload-monitoring system was designed, tested and deployed by researchers at the University of Mississippi and the National Sedimentation Laboratory in Oxford, MS. The hydrophone system was designed to be easily deployed and operated by non-experts. In addition, ...

  19. NEW NONLINEAR ACOUSTIC TECHNIQUES FOR NDE

    SciTech Connect

    J. A. TENCATE

    2000-09-01

    Acoustic nonlinearity in a medium may occur as a result of a variety of mechanisms. Some of the more common nonlinear effects may come from: (1) one or several cracks, volumetrically distributed due to age or fatigue or single disbonds or delamination; (2) imperfect grain-to-grain contacts, e.g., materials like concretes that are cemented together and have less than perfect bonds; (3) hard parts in a soft matrix, e.g., extreme duty materials like tungsten/copper alloys; or (4) atomic-scale nonlinearities. Nonlinear effects that arise from the first two mechanisms are considerably larger than the last two; thus, we have focused considerable attention on these. The most pervasive nonlinear measure of damage today is a second harmonic measurement. We show that for many cases of interest to NDE, a second harmonic measurement may not be the best choice. We examine the manifestations of nonlinearity in (nonlinear) materials with cracks and/or imperfect bonds and illustrate their applicability to NDE. For example, nonlinear resonance frequency shifts measured at increasing drive levels correlate strongly with the amount of ASR (alkali-silica reaction) damage of concrete cores. Memory effects (slow dynamics) also seem to correlate with the amount of damage.

  20. An Acoustic Communication Technique of Nanorobot Swarms for Nanomedicine Applications.

    PubMed

    Loscrí, Valeria; Vegni, Anna Maria

    2015-09-01

    In this contribution, we present a communication paradigm among nanodevices, based on acoustic vibrations for medical applications. We consider a swarm of nanorobots able to communicate in a distributed and decentralized fashion, propelled in a biological environment (i.e., the human brain). Each nanorobot is intended to i) recognize a cancer cell, ii) destroy it, and then iii) forward information about the presence of cancer formation to other nanorobots, through acoustic signals. The choice of acoustic waves as communication mean is related to the application context, where it is not advisable either to use indiscriminate chemical substances or electromagnetic waves. The effectiveness of the proposed approach is assessed in terms of achievement of the objective (i.e., to destroy the majority of tumor cells), and the velocity of detection and destruction of cancer cells, through a comparison with other related techniques. PMID:25898028

  1. An Acoustic Communication Technique of Nanorobot Swarms for Nanomedicine Applications.

    PubMed

    Loscrí, Valeria; Vegni, Anna Maria

    2015-09-01

    In this contribution, we present a communication paradigm among nanodevices, based on acoustic vibrations for medical applications. We consider a swarm of nanorobots able to communicate in a distributed and decentralized fashion, propelled in a biological environment (i.e., the human brain). Each nanorobot is intended to i) recognize a cancer cell, ii) destroy it, and then iii) forward information about the presence of cancer formation to other nanorobots, through acoustic signals. The choice of acoustic waves as communication mean is related to the application context, where it is not advisable either to use indiscriminate chemical substances or electromagnetic waves. The effectiveness of the proposed approach is assessed in terms of achievement of the objective (i.e., to destroy the majority of tumor cells), and the velocity of detection and destruction of cancer cells, through a comparison with other related techniques.

  2. Acoustic monitoring of first responder's physiology for health and performance surveillance

    NASA Astrophysics Data System (ADS)

    Scanlon, Michael V.

    2002-08-01

    Acoustic sensors have been used to monitor firefighter and soldier physiology to assess health and performance. The Army Research Laboratory has developed a unique body-contacting acoustic sensor that can monitor the health and performance of firefighters and soldiers while they are doing their mission. A gel-coupled sensor has acoustic impedance properties similar to the skin that facilitate the transmission of body sounds into the sensor pad, yet significantly repel ambient airborne noises due to an impedance mismatch. This technology can monitor heartbeats, breaths, blood pressure, motion, voice, and other indicators that can provide vital feedback to the medics and unit commanders. Diverse physiological parameters can be continuously monitored with acoustic sensors and transmitted for remote surveillance of personnel status. Body-worn acoustic sensors located at the neck, breathing mask, and wrist do an excellent job at detecting heartbeats and activity. However, they have difficulty extracting physiology during rigorous exercise or movements due to the motion artifacts sensed. Rigorous activity often indicates that the person is healthy by virtue of being active, and injury often causes the subject to become less active or incapacitated making the detection of physiology easier. One important measure of performance, heart rate variability, is the measure of beat-to-beat timing fluctuations derived from the interval between two adjacent beats. The Lomb periodogram is optimized for non-uniformly sampled data, and can be applied to non-stationary acoustic heart rate features (such as 1st and 2nd heart sounds) to derive heart rate variability and help eliminate errors created by motion artifacts. Simple peak-detection above or below a certain threshold or waveform derivative parameters can produce the timing and amplitude features necessary for the Lomb periodogram and cross-correlation techniques. High-amplitude motion artifacts may contribute to a different

  3. Density can be misleading for low-density species: benefits of passive acoustic monitoring.

    PubMed

    Rogers, Tracey L; Ciaglia, Michaela B; Klinck, Holger; Southwell, Colin

    2013-01-01

    Climate-induced changes may be more substantial within the marine environment, where following ecological change is logistically difficult, and typically expensive. As marine animals tend to produce stereotyped, long-range signals, they are ideal for repeatable surveying. In this study we illustrate the potential for calling rates to be used as a tool for determining habitat quality by using an Antarctic pack-ice seal, the leopard seal, as a model.With an understanding of the vocal behavior of a species, their seasonal and diurnal patterns, sex and age-related differences, an underwater passive-acoustic survey conducted alongside a visual survey in an arc of 4,225 km across the Davis Sea, Eastern Antarctica, showed that while acoustic and visual surveys identified similar regions as having high densities, the acoustic surveys surprisingly identified the opposite regions as being 'critical' habitats. Density surveys of species that cannot be differentiated into population classes may be misleading because overall density can be a negative indicator of habitat quality.Under special circumstances acoustics can offer enormous advantage over traditional techniques and open up monitoring to regions that are remote, difficult and expensive to work within, no longer restricting long-term community assessment to resource-wealthy communities. As climatic change affects a broad range of organisms across geographic boundaries we propose that capitalizing on the significant advances in passive acoustic technology, alongside physical acoustics and population modeling, can help in addressing ecological questions more broadly. PMID:23326339

  4. Signal processing methodologies for an acoustic fetal heart rate monitor

    NASA Technical Reports Server (NTRS)

    Pretlow, Robert A., III; Stoughton, John W.

    1992-01-01

    Research and development is presented of real time signal processing methodologies for the detection of fetal heart tones within a noise-contaminated signal from a passive acoustic sensor. A linear predictor algorithm is utilized for detection of the heart tone event and additional processing derives heart rate. The linear predictor is adaptively 'trained' in a least mean square error sense on generic fetal heart tones recorded from patients. A real time monitor system is described which outputs to a strip chart recorder for plotting the time history of the fetal heart rate. The system is validated in the context of the fetal nonstress test. Comparisons are made with ultrasonic nonstress tests on a series of patients. Comparative data provides favorable indications of the feasibility of the acoustic monitor for clinical use.

  5. Acoustic emission monitoring for assessment of steel bridge details

    SciTech Connect

    Kosnik, D. E.; Corr, D. J.; Hopwood, T.

    2011-06-23

    Acoustic emission (AE) testing was deployed on details of two large steel Interstate Highway bridges: one cantilever through-truss and one trapezoidal box girder bridge. Quantitative measurements of activity levels at known and suspected crack locations were made by monitoring AE under normal service loads (e.g., live traffic and wind). AE indications were used to direct application of radiography, resulting in identification of a previously unknown flaw, and to inform selection of a retrofit detail.

  6. 2-D acoustic VTI full waveform inversion for CCS monitoring

    NASA Astrophysics Data System (ADS)

    KIM, S.; Kim, W. K.; Min, D. J.; Jeong, W.; OH, J. W.

    2014-12-01

    These days many geophysicists have been working not only for oil and gas exploration but also for CO2 monitoring for CCS (Carbon Capture and storage). When CO2 is injected and stored to the target layer, it changes the physical properties of subsurface media like p-wave velocity, density and so on. Seismic method is one of the most widely used geophysical methods for CO2 monitoring, because it can delineate physical properties of subsurface media. To prevent CO2 from leaking out of reservoirs, most target areas require caprocks, and shale often acts as a caprock. However, shale has a strong anisotropic property. Without considering the anisotropic property of subsurface media, interpretations of seismic monitoring data can distort the CO2distribution or movement in the subsurface media. For computational efficiency, seismic data interpretation based on acoustic VTI (Vertical Transversely Isotropic) wave equations has been commonly done although it does not consider the shear waves. To investigate the importance of considering anisotropic properties in acoustic FWI (full waveform inversion) for CO2 monitoring, we compare results obtained by the acoustic VTI FWI with those of the conventional acoustic FWI for isotropic case in the frequency domain. Both methods are based on the node-based finite-element method. Numerical examples show that neglecting anisotropic properties of subsurface media can distort distribution of CO2 and degrade reliability of subsurface image obtained by FWI. Acknowledgements This work was supported by the Human Resources Development program (No. 20134010200510) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korean government Ministry of Trade, Industry, and Energy and by the "Development of Technology for CO2 Marine Geological Storage" grant funded by the Ministry of Oceans and Fisheries of Korea.

  7. Experimental source characterization techniques for studying the acoustic properties of perforates under high level acoustic excitation.

    PubMed

    Bodén, Hans

    2011-11-01

    This paper discusses experimental techniques for obtaining the acoustic properties of in-duct samples with non-linear acoustic characteristic. The methods developed are intended both for studies of non-linear energy transfer to higher harmonics for samples only accessible from one side such as wall treatment in aircraft engine ducts or automotive exhaust systems and for samples accessible from both sides such as perforates or other top sheets. When harmonic sound waves are incident on the sample nonlinear energy transfer results in sound generation at higher harmonics at the sample (perforate) surface. The idea is that these sources can be characterized using linear system identification techniques similar to one-port or two-port techniques which are traditionally used for obtaining source data for in-duct sources such as IC-engines or fans. The starting point will be so called polyharmonic distortion modeling which is used for characterization of nonlinear properties of microwave systems. It will be shown how acoustic source data models can be expressed using this theory. Source models of different complexity are developed and experimentally tested. The results of the experimental tests show that these techniques can give results which are useful for understanding non-linear energy transfer to higher harmonics.

  8. An investigation of brittle fracture using continuous acoustic emisson monitoring

    NASA Astrophysics Data System (ADS)

    Thompson, B. D.; Young, R. P.; Mair, K.

    2003-04-01

    Acoustic Emission (AE) investigations of brittle rock fracture in controlled laboratory experiments allow a detailed 3-D examination of the spatial and temporal evolution of micro-fracture growth. These observations provide valuable insights into the micro-mechanical processes involved in the development of macro-scale fault structures. Processing techniques similar to those of Earthquake Seismology are employed to locate and resolve the focal mechanisms of AE events, however at this small scale, sampling rates of 10 MHz are required. At these high sampling frequencies, technological constraints necessitate the use of triggering logic in conventional AE recording hardware. After an event is triggered, a 'downtime' period is experienced while the waveform data is downloaded. However, the AE rate increases to thousands per second, prior to dynamic fracture propagation, and so the inherent periods of downtime result in a very low proportion of events being recorded. Therefore the observational capacities of conventional AE systems are severely limited during the crucial period of fracture growth. The importance of recording a complete AE data set during the critical moments of fracture prompted the development and manufacture of a novel ultrasonic monitoring system; The Giga Recorder. This system can record up to two minutes of waveform data onto a 40 GB Random Access Memory (RAM), sampled at 10 MHz, on 16 channels. The RAM continuously rewrites, meaning at any point in time, the preceding two minutes of waveform data are stored, and can be downloaded following the critical experimental period. In addition, triggered events are recorded throughout the entire period of AE activity. Here we present results from the initial laboratory experiments using the Giga Recorder. A series of Chevron Notched Brazilian Disk granite samples were uniaxially loaded to failure, under a variety of loading rates. During each test, a tensile fracture propagated from the pre-cut notch

  9. Development and validation of a MRgHIFU non-invasive tissue acoustic property estimation technique.

    PubMed

    Johnson, Sara L; Dillon, Christopher; Odéen, Henrik; Parker, Dennis; Christensen, Douglas; Payne, Allison

    2016-11-01

    MR-guided high-intensity focussed ultrasound (MRgHIFU) non-invasive ablative surgeries have advanced into clinical trials for treating many pathologies and cancers. A remaining challenge of these surgeries is accurately planning and monitoring tissue heating in the face of patient-specific and dynamic acoustic properties of tissues. Currently, non-invasive measurements of acoustic properties have not been implemented in MRgHIFU treatment planning and monitoring procedures. This methods-driven study presents a technique using MR temperature imaging (MRTI) during low-temperature HIFU sonications to non-invasively estimate sample-specific acoustic absorption and speed of sound values in tissue-mimicking phantoms. Using measured thermal properties, specific absorption rate (SAR) patterns are calculated from the MRTI data and compared to simulated SAR patterns iteratively generated via the Hybrid Angular Spectrum (HAS) method. Once the error between the simulated and measured patterns is minimised, the estimated acoustic property values are compared to the true phantom values obtained via an independent technique. The estimated values are then used to simulate temperature profiles in the phantoms, and compared to experimental temperature profiles. This study demonstrates that trends in acoustic absorption and speed of sound can be non-invasively estimated with average errors of 21% and 1%, respectively. Additionally, temperature predictions using the estimated properties on average match within 1.2 °C of the experimental peak temperature rises in the phantoms. The positive results achieved in tissue-mimicking phantoms presented in this study indicate that this technique may be extended to in vivo applications, improving HIFU sonication temperature rise predictions and treatment assessment.

  10. Development and validation of a MRgHIFU non-invasive tissue acoustic property estimation technique.

    PubMed

    Johnson, Sara L; Dillon, Christopher; Odéen, Henrik; Parker, Dennis; Christensen, Douglas; Payne, Allison

    2016-11-01

    MR-guided high-intensity focussed ultrasound (MRgHIFU) non-invasive ablative surgeries have advanced into clinical trials for treating many pathologies and cancers. A remaining challenge of these surgeries is accurately planning and monitoring tissue heating in the face of patient-specific and dynamic acoustic properties of tissues. Currently, non-invasive measurements of acoustic properties have not been implemented in MRgHIFU treatment planning and monitoring procedures. This methods-driven study presents a technique using MR temperature imaging (MRTI) during low-temperature HIFU sonications to non-invasively estimate sample-specific acoustic absorption and speed of sound values in tissue-mimicking phantoms. Using measured thermal properties, specific absorption rate (SAR) patterns are calculated from the MRTI data and compared to simulated SAR patterns iteratively generated via the Hybrid Angular Spectrum (HAS) method. Once the error between the simulated and measured patterns is minimised, the estimated acoustic property values are compared to the true phantom values obtained via an independent technique. The estimated values are then used to simulate temperature profiles in the phantoms, and compared to experimental temperature profiles. This study demonstrates that trends in acoustic absorption and speed of sound can be non-invasively estimated with average errors of 21% and 1%, respectively. Additionally, temperature predictions using the estimated properties on average match within 1.2 °C of the experimental peak temperature rises in the phantoms. The positive results achieved in tissue-mimicking phantoms presented in this study indicate that this technique may be extended to in vivo applications, improving HIFU sonication temperature rise predictions and treatment assessment. PMID:27441427

  11. A passive acoustic monitor of treatment effectiveness during extracorporeal lithotripsy

    NASA Astrophysics Data System (ADS)

    Fedele, F.; Thomas, K.; Leighton, T. G.; Ryves, S.; Phillips, D.; Coleman, A. J.

    2011-02-01

    Although extracorporeal shockwave lithotripsy (ESWL) has now been in the clinic for at least three decades, there has been little advance in efforts (i) to estimate the efficacy of the treatment whilst it is in progress, or (ii) to determine the end-point of a treatment session in terms of the degree of stone fragmentation achieved. Previous in vitro experimentation and clinical trials have shown that a passive acoustic monitor has the potential to provide evidence of the effectiveness and end-point of lithotripsy. The system exploits secondary emissions generated during shock-tissue interaction, whose features depend on the quality of tissue at the beam focus. This prototype was developed into the first commercially available clinical ESWL treatment monitor (Precision Acoustic Ltd, Dorchester, UK), and a unit has been acquired and tested in the clinical routine by urologists at Guy's and St Thomas NHS Trust in March 2009. This paper critically assesses the performance of the new system for the first 25 treatments monitored. The ESWL monitor correctly predicted the treatment outcome of 15 of the 18 treatments that were followed-up clinically. In addition, it was noted that the measure of treatment effectiveness provided by the monitor after 500 shocks was predictive of the final treatment outcome (p < 0.001). This suggests that the system could be used in pre-assessment; indicating if the stone is susceptible to ESWL or if the patient should be sent for surgery.

  12. Combining whistle acoustic parameters to discriminate Mediterranean odontocetes during passive acoustic monitoring.

    PubMed

    Azzolin, Marta; Gannier, Alexandre; Lammers, Marc O; Oswald, Julie N; Papale, Elena; Buscaino, Giuseppa; Buffa, Gaspare; Mazzola, Salvatore; Giacoma, Cristina

    2014-01-01

    Acoustic observation can complement visual observation to more effectively monitor occurrence and distribution of marine mammals. For effective acoustic censuses, calibration methods must be determined by joint visual and acoustic studies. Research is still needed in the field of acoustic species identification, particularly for smaller odontocetes. From 1994 to 2012, whistles of four odontocete species were recorded in different areas of the Mediterranean Sea to determine how reliably these vocalizations can be classified to species. Recordings were attributed to species by simultaneous visual observation. The results of this study highlight that the frequency parameters, which are linked to physical features of animals, show lower variability than modulation parameters, which are likely to be more dependent on complex eco-ethological contexts. For all the studied species, minimum and maximum frequencies were linearly correlated with body size. DFA and Classification Tree Analysis (CART) show that these parameters were the most important for classifying species; however, both statistical methods highlighted the need for combining them with the number of contour minima and contour maxima for correct classification. Generally, DFA and CART results reflected both phylogenetic distance (especially for common and striped dolphins) and the size of the species.

  13. Acoustical standards in engineering acoustics

    NASA Astrophysics Data System (ADS)

    Burkhard, Mahlon D.

    2001-05-01

    The Engineering Acoustics Technical Committee is concerned with the evolution and improvement of acoustical techniques and apparatus, and with the promotion of new applications of acoustics. As cited in the Membership Directory and Handbook (2002), the interest areas include transducers and arrays; underwater acoustic systems; acoustical instrumentation and monitoring; applied sonics, promotion of useful effects, information gathering and transmission; audio engineering; acoustic holography and acoustic imaging; acoustic signal processing (equipment and techniques); and ultrasound and infrasound. Evident connections between engineering and standards are needs for calibration, consistent terminology, uniform presentation of data, reference levels, or design targets for product development. Thus for the acoustical engineer standards are both a tool for practices, for communication, and for comparison of his efforts with those of others. Development of many standards depends on knowledge of the way products are put together for the market place and acoustical engineers provide important input to the development of standards. Acoustical engineers and members of the Engineering Acoustics arm of the Society both benefit from and contribute to the Acoustical Standards of the Acoustical Society.

  14. Munitions classification using an Acoustic Resonance Spectroscopic technique

    SciTech Connect

    Roberts, R.S.; Chen, J.T.; Vela, O.A.; Lewis, P.S.

    1993-12-01

    In support of the Bilateral Chemical Weapons Agreement between the United States and Russia, Los Alamos National Laboratory has developed a nondestructive evaluation (NDE) technique that discriminates between different types of artillery munitions. This NDE classification technique allows on-site inspectors to rapidly classify the munitions as chemical or high explosive, and furthermore discriminates between various subclasses of these types of munitions. This technique, based on acoustic resonance measurements, has been successfully demonstrated on a wide variety of high explosive and chemical munitions. The technique consists of building templates of spectral features from sets of known munitions. Spectral features of unknown munitions are compared with a library of templates, and the degree of match between the features and the templates is used to classify the munition. This paper describes the technique, including the feature extraction, clustering and classification algorithms.

  15. Acoustic source identification using a Generalized Weighted Inverse Beamforming technique

    NASA Astrophysics Data System (ADS)

    Presezniak, Flavio; Zavala, Paulo A. G.; Steenackers, Gunther; Janssens, Karl; Arruda, Jose R. F.; Desmet, Wim; Guillaume, Patrick

    2012-10-01

    In the last years, acoustic source identification has gained special attention, mainly due to new environmental norms, urbanization problems and more demanding acoustic comfort expectation of consumers. From the current methods, beamforming techniques are of common use, since normally demands affordable data acquisition effort, while producing clear source identification in most of the applications. In order to improve the source identification quality, this work presents a method, based on the Generalized Inverse Beamforming, that uses a weighted pseudo-inverse approach and an optimization procedure, called Weighted Generalized Inverse Beamforming. To validate this method, a simple case of two compact sources in close vicinity in coherent radiation was investigated by numerical and experimental assessment. Weighted generalized inverse results are compared to the ones obtained by the conventional beamforming, MUltiple Signal Classification, and Generalized Inverse Beamforming. At the end, the advantages of the proposed method are outlined together with the computational effort increase compared to the Generalized Inverse Beamforming.

  16. Acoustical Characteristics of Mastication Sounds: Application of Speech Analysis Techniques

    NASA Astrophysics Data System (ADS)

    Brochetti, Denise

    Food scientists have used acoustical methods to study characteristics of mastication sounds in relation to food texture. However, a model for analysis of the sounds has not been identified, and reliability of the methods has not been reported. Therefore, speech analysis techniques were applied to mastication sounds, and variation in measures of the sounds was examined. To meet these objectives, two experiments were conducted. In the first experiment, a digital sound spectrograph generated waveforms and wideband spectrograms of sounds by 3 adult subjects (1 male, 2 females) for initial chews of food samples differing in hardness and fracturability. Acoustical characteristics were described and compared. For all sounds, formants appeared in the spectrograms, and energy occurred across a 0 to 8000-Hz range of frequencies. Bursts characterized waveforms for peanut, almond, raw carrot, ginger snap, and hard candy. Duration and amplitude of the sounds varied with the subjects. In the second experiment, the spectrograph was used to measure the duration, amplitude, and formants of sounds for the initial 2 chews of cylindrical food samples (raw carrot, teething toast) differing in diameter (1.27, 1.90, 2.54 cm). Six adult subjects (3 males, 3 females) having normal occlusions and temporomandibular joints chewed the samples between the molar teeth and with the mouth open. Ten repetitions per subject were examined for each food sample. Analysis of estimates of variation indicated an inconsistent intrasubject variation in the acoustical measures. Food type and sample diameter also affected the estimates, indicating the variable nature of mastication. Generally, intrasubject variation was greater than intersubject variation. Analysis of ranks of the data indicated that the effect of sample diameter on the acoustical measures was inconsistent and depended on the subject and type of food. If inferences are to be made concerning food texture from acoustical measures of mastication

  17. Acoustic methods to monitor sliver linear density and yarn strength

    DOEpatents

    Sheen, Shuh-Haw; Chien, Hual-Te; Raptis, Apostolos C.

    1997-01-01

    Methods and apparatus are provided for monitoring sliver and yarn characteristics. Transverse waves are generated relative to the sliver or yarn. At least one acoustic sensor is in contact with the sliver or yarn for detecting waves coupled to the sliver or yarn and for generating a signal. The generated signal is processed to identify the predefined characteristics including sliver or yarn linear density. The transverse waves can be generated with a high-powered acoustic transmitter spaced relative to the sliver or yarn with large amplitude pulses having a central frequency in a range between 20 KHz and 40 KHz applied to the transmitter. The transverse waves can be generated by mechanically agitating the sliver or yarn with a tapping member.

  18. Monitoring of Temperature Fatigue Failure Mechanism for Polyvinyl Alcohol Fiber Concrete Using Acoustic Emission Sensors

    PubMed Central

    Li, Dongsheng; Cao, Hai

    2012-01-01

    The applicability of acoustic emission (AE) techniques to monitor the mechanism of evolution of polyvinyl alcohol (PVA) fiber concrete damage under temperature fatigue loading is investigated. Using the temperature fatigue test, real-time AE monitoring data of PVA fiber concrete is achieved. Based on the AE signal characteristics of the whole test process and comparison of AE signals of PVA fiber concretes with different fiber contents, the damage evolution process of PVA fiber concrete is analyzed. Finally, a qualitative evaluation of the damage degree is obtained using the kurtosis index and b-value of AE characteristic parameters. The results obtained using both methods are discussed. PMID:23012555

  19. The Doppler Effect based acoustic source separation for a wayside train bearing monitoring system

    NASA Astrophysics Data System (ADS)

    Zhang, Haibin; Zhang, Shangbin; He, Qingbo; Kong, Fanrang

    2016-01-01

    Wayside acoustic condition monitoring and fault diagnosis for train bearings depend on acquired acoustic signals, which consist of mixed signals from different train bearings with obvious Doppler distortion as well as background noises. This study proposes a novel scheme to overcome the difficulties, especially the multi-source problem in wayside acoustic diagnosis system. In the method, a time-frequency data fusion (TFDF) strategy is applied to weaken the Heisenberg's uncertainty limit for a signal's time-frequency distribution (TFD) of high resolution. Due to the Doppler Effect, the signals from different bearings have different time centers even with the same frequency. A Doppler feature matching search (DFMS) algorithm is then put forward to locate the time centers of different bearings in the TFD spectrogram. With the determined time centers, time-frequency filters (TFF) are designed with thresholds to separate the acoustic signals in the time-frequency domain. Then the inverse STFT (ISTFT) is taken and the signals are recovered and filtered aiming at each sound source. Subsequently, a dynamical resampling method is utilized to remove the Doppler Effect. Finally, accurate diagnosis for train bearing faults can be achieved by applying conventional spectrum analysis techniques to the resampled data. The performance of the proposed method is verified by both simulated and experimental cases. It shows that it is effective to detect and diagnose multiple defective bearings even though they produce multi-source acoustic signals.

  20. Power cepstrum technique with application to model helicopter acoustic data

    NASA Technical Reports Server (NTRS)

    Martin, R. M.; Burley, C. L.

    1986-01-01

    The application of the power cepstrum to measured helicopter-rotor acoustic data is investigated. A previously applied correction to the reconstructed spectrum is shown to be incorrect. For an exact echoed signal, the amplitude of the cepstrum echo spike at the delay time is linearly related to the echo relative amplitude in the time domain. If the measured spectrum is not entirely from the source signal, the cepstrum will not yield the desired echo characteristics and a cepstral aliasing may occur because of the effective sample rate in the frequency domain. The spectral analysis bandwidth must be less than one-half the echo ripple frequency or cepstral aliasing can occur. The power cepstrum editing technique is a useful tool for removing some of the contamination because of acoustic reflections from measured rotor acoustic spectra. The cepstrum editing yields an improved estimate of the free field spectrum, but the correction process is limited by the lack of accurate knowledge of the echo transfer function. An alternate procedure, which does not require cepstral editing, is proposed which allows the complete correction of a contaminated spectrum through use of both the transfer function and delay time of the echo process.

  1. Development of acoustic health monitoring for railroad tank cars

    NASA Astrophysics Data System (ADS)

    Gostautas, Richard; Finlayson, Richard; Godinez, Valery; Pollock, Adrian; Penya, Jose

    2005-05-01

    This paper presents the research and development of an Acoustic Health Monitoring (AHM) system that uses Guided Lamb Wave (GLW) technology to determine the thickness of railroad tank car shells for identification of wall loss due to corrosion. In recent regulatory changes, the emphasis has shifted from the traditional hydrotest to more modern methods for assuring tank car integrity. The new generation of maintenance programs will rely heavily on nondestructive testing, and will use damage tolerance concepts and risk analysis to establish inspection frequencies and items to inspect. It is the responsibility of the owners to set up experience-based maintenance programs that are suitable for the working conditions of their own particular fleets. Development of an ideal AHM system for railroad cars would be an instrument that incorporates Acoustic Emission (AE) and GLW technology. The combination of active and passive acoustic technologies integrated into a single system would be a highly efficient means of determining the structural integrity of tank cars. The integration of the GLW technology will allow identification of corrosion wall loss in a zone between two sensors, rather than at a single point (traditional ultrasonic thickness measurements). Thus, a much larger area of the structure can be inspected for approximately the same inspection cost. With a suitable integration of this new technology into the overall inspection and corrosion management program, the fleet can be more efficiently maintained and the risk of accidental release through progressive corrosion damage can be significantly reduced.

  2. Use of acoustic monitoring system for debris flow discharge evaluation

    NASA Astrophysics Data System (ADS)

    Galgaro, A. G.; Tecca, P. R.; Genevois, R.; Deganutti, A. M.

    2003-04-01

    In 1997 an automated system for monitoring of debris flows has been installed in the Acquabona channel Dolomites, Italy. Induction geophones, with a specific frequency of 10 Hz, measure the amplitude of vertical ground vibrations generated by the passage of a flowing mass along the channel. Continuous acoustic logs and ultrasonic hydrograph recorded at the lower-channel measurement station for the debris flow of August 17, 1998, show a striking correspondence. This correspondence, already observed in different flow sites, is represented by the best fit between flow depth and flow sensor amplitude. Average front velocity for surges, calculated from the signal peak time shift and the distance between the sensors along the flow path, range between 2.00 and 7.7 m/s. As the ultrasonic sensor provides a way to measure the variation of the flow section area with the flow depth, the debris flow peak discharge may be estimated; obtained values of debris flow peak discharge range from 4 and 30 m3/s. Volumes were calculated by integrating instantaneous discharges through the hydrograph and by integrating the geophone log (acoustic flux). Volumes of 13700 m3 and 15500 m3 have been respectively obtained. The slight difference between the two values may result from the fact that acoustic records: i) are sensitive to the high frequencies, typical of the debris flow tails; ii) sum up the contributions sent by the whole flowing mass, while the ecometer detect the flow depth at every time at only one section. As a consequence the rising of the whole geophone log gives a higher value at the integration result. This only acoustic system can give a reasonably proxy for discharge and total volumes involved, which are among the most important parameters for debris flow hazard assessment and planning countermeasures. This methodology can be used in other debris flow sites if they are calibrated by the acoustic characterization of debris, obtained by both seismic surveys and SPT tests, and

  3. Acoustic Methods to Monitor Protein Crystallization and to Detect Protein Crystals in Suspensions of Agarose and Lipidic Cubic Phase.

    PubMed

    Ericson, Daniel L; Yin, Xingyu; Scalia, Alexander; Samara, Yasmin N; Stearns, Richard; Vlahos, Harry; Ellson, Richard; Sweet, Robert M; Soares, Alexei S

    2016-02-01

    Improvements needed for automated crystallography include crystal detection and crystal harvesting. A technique that uses acoustic droplet ejection to harvest crystals was previously reported. Here a method is described for using the same acoustic instrument to detect protein crystals and to monitor crystal growth. Acoustic pulses were used to monitor the progress of crystallization trials and to detect the presence and location of protein crystals. Crystals were detected, and crystallization was monitored in aqueous solutions and in lipidic cubic phase. Using a commercially available acoustic instrument, crystals measuring ~150 µm or larger were readily detected. Simple laboratory techniques were used to increase the sensitivity to 50 µm by suspending the crystals away from the plastic surface of the crystallization plate. This increased the sensitivity by separating the strong signal generated by the plate bottom that can mask the signal from small protein crystals. It is possible to further boost the acoustic reflection from small crystals by reducing the wavelength of the incident sound pulse, but our current instrumentation does not allow this option. In the future, commercially available sound-emitting transducers with a characteristic frequency near 300 MHz should detect and monitor the growth of individual 3 µm crystals.

  4. Application of Acoustic Techniques for Characterization of Biological Samples

    NASA Astrophysics Data System (ADS)

    Tittmann, Bernhard R.; Ebert, Anne

    The atomic force microscope (AFM) is emerging as a powerful tool in cell biology. Originally developed for high-resolution imaging purposes, the AFM also has unique capabilities as a nano-indenter to probe the dynamic viscoelastic material properties of living cells in culture. In particular, AFM elastography combines imaging and indentation modalities to map the spatial distribution of cell mechanical properties, which in turn reflect the structure and function of the underlying cytoskeleton. Such measurements have contributed to our understanding of cell mechanics and cell biology and appear to be sensitive to the presence of disease in individual cells. Examples of applications and considerations on the effective capability of ultrasonic AFM techniques on biological samples (both mammalian and plant) are reported in this chapter. Included in the discussion is scanning near-field ultrasound holography an acoustic technique which has been used to image structure and in particular nanoparticles inside cells. For illustration an example that is discussed in some detail is a technique for rapid in vitro single-cell elastography. The technique is based on atomic force acoustic microscopy (AFAM) but (1) requires only a few minutes of scan time, (2) can be used on live cells briefly removed from most of the nutrient fluid, (3) does negligible harm or damage to the cell, (4) provides semi-quantitative information on the distribution of modulus across the cell, and (5) yields data with 1-10 nm resolution. The technique is shown to enable rapid assessment of physical/biochemical signals on the cell modulus and contributes to current understanding of cell mechanics.

  5. Monitoring Microbe-Induced Physical Property Changes Using High-Frequency Acoustic Waveform Data

    NASA Astrophysics Data System (ADS)

    Williams, K. H.; Brockman, F. J.; Johnson, L. R.

    2002-12-01

    A laboratory investigation was undertaken to determine the effect of microbially generated gas in controlled, saturated sediment columns utilizing a novel technique involving acoustic wave propagation. Specifically, the effect of N2 gas production and the resulting hypothesized plugging of pore throats by gas bubbles was evaluated during denitrification by Pseudomonas stutzeri in pre-sterilized sediment columns. The propagation of high frequency acoustic waves through the sediment columns was used to locate those regions in the column where gas accumulation occurred. Over a period of six weeks, regions of gas accumulation resulted in the attenuation of acoustic wave energies with the decreases in amplitude typically greater than one order of magnitude. The temporal production of N2 gas was evaluated quantitatively using the stable isotope 15N in the form of added Na15NO3. This was done to ascertain the origin (biotic or abiotic) of any produced gas with the results showing a dramatic increase in microbe-respired 15N2. Hydraulic conductivity (Ks) measurements made over the experimental period establish the rate and degree of pore throat blocking with the result being a reduction in Ks by more than 70 percent. The results were compared to a nutrient-amended but non-inoculated control column which showed neither a decrease in acoustic wave amplitudes nor hydraulic conductivity over the same time-period. Final destructive analysis of one column was performed in order to assess the cell density of denitrifying microbes throughout the column. Cell densities were found to be in close agreement with the stoichiometric predictions made prior to initiation of the experiment. Evaluation of the multiple data sets suggests that microbial gas production is both directly detectable using the high frequency acoustic wave approach and capable of significantly altering saturated flow conditions. The acoustic approach may be useful for time-course monitoring of locations of high

  6. Tools for automated acoustic monitoring within the R package monitoR

    USGS Publications Warehouse

    Katz, Jonathan; Hafner, Sasha D.; Donovan, Therese

    2016-01-01

    The R package monitoR contains tools for managing an acoustic-monitoring program including survey metadata, template creation and manipulation, automated detection and results management. These tools are scalable for use with small projects as well as larger long-term projects and those with expansive spatial extents. Here, we describe typical workflow when using the tools in monitoR. Typical workflow utilizes a generic sequence of functions, with the option for either binary point matching or spectrogram cross-correlation detectors.

  7. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  8. Acoustic emission monitoring of HFIR vessel during hydrostatic testing. Final report

    SciTech Connect

    Friesel, M.A.; Dawson, J.F.

    1992-08-01

    This report discusses the results and conclusions reached from applying acoustic emission monitoring to surveillance of the High Flux Isotope Reactor vessel during pressure testing. The objective of the monitoring was to detect crack growth and/or fluid leakage should it occur during the pressure test. The report addresses the approach, acoustic emission instrumentation, installation, calibration, and test results.

  9. Mechanical degradation of cross-ply laminates monitored by acoustic emission

    NASA Astrophysics Data System (ADS)

    Paipetis, A.; Xyrafa, M.; Barkoula, N. M.; Matikas, T. E.; Aggelis, D. G.

    2011-04-01

    This study deals with the investigation of cross ply composites failure by acoustic emission (AE). Broadband AE sensors monitor the different sources of failure in coupons of this material during a tensile loading-unloading test. The cumulative number of AE activity, and other qualitative indices based on the shape of the waves, were well correlated to the sustained load. AE parameters indicate the shift of failure mechanisms within the composite as the load increases. The ultimate goal is a methodology based on NDT techniques for real time characterization of the degradation and identification of the fracture stage of advanced composite materials.

  10. A multi-channel acoustics monitor for perioperative respiratory monitoring: preliminary data.

    PubMed

    Jafarian, Kamal; Amineslami, Majid; Hassani, Kamran; Navidbakhsh, Mahdi; Lahiji, Mohammad Niakan; Doyle, D John

    2016-02-01

    This study pertains to a six-channel acoustic monitoring system for use in patient monitoring during or after surgery. The base hardware consists of a USB data acquisition system, a custom-built six-channel amplification system, and a series of microphones of various designs. The software is based on the MATLAB platform with data acquisition drivers installed. The displayed information includes: time domain signals, frequency domain signals, and tools to aid in the detection of endobronchial intubation. We hypothesize that the above mentioned arrangement may be helpful to the anesthesiologist in recognizing clinical conditions like wheezing, bronchospasm, endobronchial intubation, and apnea. The study also evaluated various types of microphone designs used to transduce breath sounds. The system also features selectable band-pass filtering using MATLAB algorithms as well as a collection of recordings obtained with the system to establish what respiratory acoustic signals look like under various conditions.

  11. A multi-channel acoustics monitor for perioperative respiratory monitoring: preliminary data.

    PubMed

    Jafarian, Kamal; Amineslami, Majid; Hassani, Kamran; Navidbakhsh, Mahdi; Lahiji, Mohammad Niakan; Doyle, D John

    2016-02-01

    This study pertains to a six-channel acoustic monitoring system for use in patient monitoring during or after surgery. The base hardware consists of a USB data acquisition system, a custom-built six-channel amplification system, and a series of microphones of various designs. The software is based on the MATLAB platform with data acquisition drivers installed. The displayed information includes: time domain signals, frequency domain signals, and tools to aid in the detection of endobronchial intubation. We hypothesize that the above mentioned arrangement may be helpful to the anesthesiologist in recognizing clinical conditions like wheezing, bronchospasm, endobronchial intubation, and apnea. The study also evaluated various types of microphone designs used to transduce breath sounds. The system also features selectable band-pass filtering using MATLAB algorithms as well as a collection of recordings obtained with the system to establish what respiratory acoustic signals look like under various conditions. PMID:25869899

  12. Modern Techniques in Acoustical Signal and Image Processing

    SciTech Connect

    Candy, J V

    2002-04-04

    Acoustical signal processing problems can lead to some complex and intricate techniques to extract the desired information from noisy, sometimes inadequate, measurements. The challenge is to formulate a meaningful strategy that is aimed at performing the processing required even in the face of uncertainties. This strategy can be as simple as a transformation of the measured data to another domain for analysis or as complex as embedding a full-scale propagation model into the processor. The aims of both approaches are the same--to extract the desired information and reject the extraneous, that is, develop a signal processing scheme to achieve this goal. In this paper, we briefly discuss this underlying philosophy from a ''bottom-up'' approach enabling the problem to dictate the solution rather than visa-versa.

  13. Operational Performance Analysis of Passive Acoustic Monitoring for Killer Whales

    SciTech Connect

    Matzner, Shari; Fu, Tao; Ren, Huiying; Deng, Zhiqun; Sun, Yannan; Carlson, Thomas J.

    2011-09-30

    For the planned tidal turbine site in Puget Sound, WA, the main concern is to protect Southern Resident Killer Whales (SRKW) due to their Endangered Species Act status. A passive acoustic monitoring system is proposed because the whales emit vocalizations that can be detected by a passive system. The algorithm for detection is implemented in two stages. The first stage is an energy detector designed to detect candidate signals. The second stage is a spectral classifier that is designed to reduce false alarms. The evaluation presented here of the detection algorithm incorporates behavioral models of the species of interest, environmental models of noise levels and potential false alarm sources to provide a realistic characterization of expected operational performance.

  14. Acoustic emission monitoring of recycled aggregate concrete under bending

    NASA Astrophysics Data System (ADS)

    Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    The amount of construction and demolition waste has increased considerably over the last few years, making desirable the reuse of this waste in the concrete industry. In the present study concrete specimens are subjected at the age of 28 days to four-point bending with concurrent monitoring of their acoustic emission (AE) activity. Several concrete mixtures prepared using recycled aggregates at various percentages of the total coarse aggregate and also a reference mix using natural aggregates, were included to investigate their influence of the recycled aggregates on the load bearing capacity, as well as on the fracture mechanisms. The results reveal that for low levels of substitution the influence of using recycled aggregates on the flexural strength is negligible while higher levels of substitution lead into its deterioration. The total AE activity, as well as the AE signals emitted during failure, was related to flexural strength. The results obtained during test processing were found to be in agreement with visual observation.

  15. Surface Acoustic Wave (SAW) Resonators for Monitoring Conditioning Film Formation.

    PubMed

    Hohmann, Siegfried; Kögel, Svea; Brunner, Yvonne; Schmieg, Barbara; Ewald, Christina; Kirschhöfer, Frank; Brenner-Weiß, Gerald; Länge, Kerstin

    2015-01-01

    We propose surface acoustic wave (SAW) resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA) and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM) sensor measurements, which confirmed the suitability of the SAW resonators for this application. PMID:26007735

  16. Surface Acoustic Wave (SAW) Resonators for Monitoring Conditioning Film Formation.

    PubMed

    Hohmann, Siegfried; Kögel, Svea; Brunner, Yvonne; Schmieg, Barbara; Ewald, Christina; Kirschhöfer, Frank; Brenner-Weiß, Gerald; Länge, Kerstin

    2015-05-21

    We propose surface acoustic wave (SAW) resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA) and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM) sensor measurements, which confirmed the suitability of the SAW resonators for this application.

  17. Surface Acoustic Wave (SAW) Resonators for Monitoring Conditioning Film Formation

    PubMed Central

    Hohmann, Siegfried; Kögel, Svea; Brunner, Yvonne; Schmieg, Barbara; Ewald, Christina; Kirschhöfer, Frank; Brenner-Weiß, Gerald; Länge, Kerstin

    2015-01-01

    We propose surface acoustic wave (SAW) resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA) and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM) sensor measurements, which confirmed the suitability of the SAW resonators for this application. PMID:26007735

  18. Computational and experimental techniques for coupled acoustic/structure interactions.

    SciTech Connect

    Sumali, Anton Hartono; Pierson, Kendall Hugh; Walsh, Timothy Francis; Dohner, Jeffrey Lynn; Reese, Garth M.; Day, David Minot

    2004-01-01

    This report documents the results obtained during a one-year Laboratory Directed Research and Development (LDRD) initiative aimed at investigating coupled structural acoustic interactions by means of algorithm development and experiment. Finite element acoustic formulations have been developed based on fluid velocity potential and fluid displacement. Domain decomposition and diagonal scaling preconditioners were investigated for parallel implementation. A formulation that includes fluid viscosity and that can simulate both pressure and shear waves in fluid was developed. An acoustic wave tube was built, tested, and shown to be an effective means of testing acoustic loading on simple test structures. The tube is capable of creating a semi-infinite acoustic field due to nonreflecting acoustic termination at one end. In addition, a micro-torsional disk was created and tested for the purposes of investigating acoustic shear wave damping in microstructures, and the slip boundary conditions that occur along the wet interface when the Knudsen number becomes sufficiently large.

  19. Cavitation controlled acoustic probe for fabric spot cleaning and moisture monitoring

    DOEpatents

    Sheen, Shuh-Haw; Chien, Hual-Te; Raptis, Apostolos C.

    1997-01-01

    A method and apparatus are provided for monitoring a fabric. An acoustic probe generates acoustic waves relative to the fabric. An acoustic sensor, such as an accelerometer is coupled to the acoustic probe for generating a signal representative of cavitation activity in the fabric. The generated cavitation activity representative signal is processed to indicate moisture content of the fabric. A feature of the invention is a feedback control signal is generated responsive to the generated cavitation activity representative signal. The feedback control signal can be used to control the energy level of the generated acoustic waves and to control the application of a cleaning solution to the fabric.

  20. The application of acoustic emission technique to fatigue crack measurement. [in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Davis, W. T.; Crews, J. H., Jr.

    1974-01-01

    The applicability of acoustic emission technique to measure fatigue cracks in aluminum alloy specimens was investigated. There are several variables, such as the metallurgical and the physical treatment of the specimen, that can affect the level of acoustic activity of a fatigue specimen. It is therefore recommended that the acoustic emission technique be supplemented by other nondestructive evaluation methods to obtain quantitative data on crack growth.

  1. Distance-domain based localization techniques for acoustic emission sources: a comparative study

    NASA Astrophysics Data System (ADS)

    Grabowski, Krzysztof; Gawronski, Mateusz; Nakatani, Hayato; Packo, Pawel; Baran, Ireneusz; Spychalski, Wojciech; Staszewski, Wieslaw; Uhl, Tadeusz; Kundu, Tribikram

    2015-04-01

    Acoustic Emission phenomenon is of great importance for analyzing and monitoring health status of critical structural components. In acoustic emission, elastic waves generated by sources propagate through the structure and are acquired by networks of sensors. Ability to accurately locate the event strongly depends on the type of medium (e.g. geometrical features) and material properties, that result in wave signals distortion. These effects manifest themselves particularly in plate structures due to intrinsic dispersive nature of Lamb waves. In this paper two techniques for acoustic emission source localization in elastic plates are compared: one based on a time-domain distance transform and the second one is a two-step hybrid technique. A time-distance domain transform approach, transforms the time-domain waveforms into the distance domain by using wavenumber-frequency mapping. The transform reconstructs the source signal removing distortions resulting from dispersion effects. The method requires input of approximate material properties and geometrical features of the structure that are relatively easy to estimate prior to measurement. Hence, the method is of high practical interest. Subsequently, a two-step hybrid technique, which does not require apriori knowledge of material parameters, is employed. The method requires a setup of two predefined clusters of three sensors in each. The Lamb wave source is localized from the intersection point of the predicted wave propagation directions for the two clusters. The second step of the two-step hybrid technique improves the prediction by minimizing an objective function. The two methods are compared for analytic, simulated and experimental signals.

  2. Passive acoustic monitoring of human physiology during activity indicates health and performance of soldiers and firefighters

    NASA Astrophysics Data System (ADS)

    Scanlon, Michael V.

    2003-04-01

    The Army Research Laboratory has developed a unique gel-coupled acoustic physiological monitoring sensor that has acoustic impedance properties similar to the skin. This facilitates the transmission of body sounds into the sensor pad, yet significantly repels ambient airborne noises due to an impedance mismatch. The sensor's sensitivity and bandwidth produce excellent signatures for detection and spectral analysis of diverse physiological events. Acoustic signal processing detects heartbeats, breaths, wheezes, coughs, blood pressure, activity, motion, and voice for communication and automatic speech recognition. The health and performance of soldiers, firefighters, and other first responders in strenuous and hazardous environments can be continuously and remotely monitored with body-worn acoustic sensors. Comfortable acoustic sensors can be in a helmet or in a strap around the neck, chest, and wrist. Noise-canceling sensor arrays help remove out-of-phase motion noise and enhance covariant physiology by using two acoustic sensors on the front sides of the neck and two additional acoustic sensors on each wrist. Pulse wave transit time between neck and wrist acoustic sensors will indicate systolic blood pressure. Larger torso-sized arrays can be used to acoustically inspect the lungs and heart, or built into beds for sleep monitoring. Acoustics is an excellent input for sensor fusion.

  3. Distributed acoustic fibre optic sensors for condition monitoring of pipelines

    NASA Astrophysics Data System (ADS)

    Hussels, Maria-Teresa; Chruscicki, Sebastian; Habib, Abdelkarim; Krebber, Katerina

    2016-05-01

    Industrial piping systems are particularly relevant to public safety and the continuous availability of infrastructure. However, condition monitoring systems based on many discrete sensors are generally not well-suited for widespread piping systems due to considerable installation effort, while use of distributed fibre-optic sensors would reduce this effort to a minimum. Specifically distributed acoustic sensing (DAS) is employed for detection of third-party threats and leaks in oil and gas pipelines in recent years and can in principle also be applied to industrial plants. Further possible detection routes amenable by DAS that could identify damage prior to emission of medium are subject of a current project at BAM, which aims at qualifying distributed fibre optic methods such as DAS as a means for spatially continuous monitoring of industrial piping systems. Here, first tests on a short pipe are presented, where optical fibres were applied directly to the surface. An artificial signal was used to define suitable parameters of the measurement system and compare different ways of applying the sensor.

  4. Real-time vehicle noise cancellation techniques for gunshot acoustics

    NASA Astrophysics Data System (ADS)

    Ramos, Antonio L. L.; Holm, Sverre; Gudvangen, Sigmund; Otterlei, Ragnvald

    2012-06-01

    Acoustical sniper positioning systems rely on the detection and direction-of-arrival (DOA) estimation of the shockwave and the muzzle blast in order to provide an estimate of a potential snipers location. Field tests have shown that detecting and estimating the DOA of the muzzle blast is a rather difficult task in the presence of background noise sources, e.g., vehicle noise, especially in long range detection and absorbing terrains. In our previous work presented in the 2011 edition of this conference we highlight the importance of improving the SNR of the gunshot signals prior to the detection and recognition stages, aiming at lowering the false alarm and miss-detection rates and, thereby, increasing the reliability of the system. This paper reports on real-time noise cancellation techniques, like Spectral Subtraction and Adaptive Filtering, applied to gunshot signals. Our model assumes the background noise as being short-time stationary and uncorrelated to the impulsive gunshot signals. In practice, relatively long periods without signal occur and can be used to estimate the noise spectrum and its first and second order statistics as required in the spectral subtraction and adaptive filtering techniques, respectively. The results presented in this work are supported with extensive simulations based on real data.

  5. Ultrasonic techniques for process monitoring and control.

    SciTech Connect

    Chien, H.-T.

    1999-03-24

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

  6. Embedded and conventional ultrasonic sensors for monitoring acoustic emission during thermal fatigue

    NASA Astrophysics Data System (ADS)

    Trujillo, Blaine; Zagrai, Andrei

    2016-04-01

    Acoustic emission is widely used for monitoring pressure vessels, pipes, critical infrastructure, as well as land, sea and air vehicles. It is one of dominant approaches to explore material degradation under fatigue and events leading to material fracture. Addressing a recent interest in structural health monitoring of space vehicles, a need has emerged to evaluate material deterioration due to thermal fatigue during spacecraft atmospheric reentry. Thermal fatigue experiments were conducted, in which aluminum plates were subjected to localized heating and acoustic emission was monitoring by embedded and conventional acoustic emission sensors positioned at various distances from a heat source. At the same time, surface temperature of aluminum plates was monitored using an IR camera. Acoustic emission counts collected by embedded sensors were compared to counts measured with conventional acoustic emission sensors. Both types of sensors show noticeable increase of acoustic emission activity as localized heating source was applied to aluminum plates. Experimental data demonstrate correlation between temperature increase on the surface of the plates and increase in measured acoustic emission activity. It is concluded that under particular conditions, embedded piezoelectric wafer active sensors can be used for acoustic emission monitoring of thermally-induced structural degradation.

  7. Air pollution monitoring by advanced spectroscopic techniques.

    PubMed

    Hodgeson, J A; McClenny, W A; Hanst, P L

    1973-10-19

    The monitoring requirements related to air pollution are many and varied. The molecules of concern differ greatly in their chemical and physical properties, in the nature of their environment, and in their concentration ranges. Furthermore, the application may have specific requirements such as rapid response time, ultrasensitivity, multipollutant capability, or capability for remote measurements. For these reasons, no single spectroscopic technique appears to offer a panacea for all monitoring needs. Instead we have attempted to demonstrate in the above discussion that, regardless of the difficulty and complexity of the monitoring problems, spectroscopy offers many tools by which such problems may be solved.

  8. MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED THERMAL-ACOUSTIC EFFECT TO MEASURE UNBURNED CARBON

    SciTech Connect

    Robert C. Brown; Robert J. Weber; Jeffrey J. Swetelitsch

    2005-01-01

    The objective of this project is to explore microwave-excited thermal-acoustic (META) phenomena for quantitative analysis of granular and powdered materials, with the culmination of the research to be an on-line carbon-in-ash monitor for coal-fired power plants. This technique of analyzing unburned carbon in fly ash could be a less tedious and time consuming method as compared to the traditional LOI manual procedure. Phase 1 of the research focused on off-line single-frequency thermal-acoustic measurements where an off-line fly ash monitor was constructed that could operate as analytical tool to explore instrument and methodology parameters for quantifying the microwave-excited thermal-acoustic effect of carbon in fly ash, and it was determined that the off-line thermal-acoustic technique could predict the carbon content of a random collection of fly ashes with a linear correlation constant of R{sup 2} = 0.778. Much higher correlations are expected for fly ashes generated from a single boiler. Phase 2 of the research developing a methodology to generate microwave spectra of various powders, including fly ash, coal, and inorganic minerals, and to determine if these microwave spectra could be used for chemical analyses. Although different minerals produced different responses, higher resolution microwave spectra would be required to be able to distinguish among minerals. Phase 3 of the research focused on the development of an on-line fly ash monitor that could be adapted to measure either a thermal-acoustic or thermal-elastic response to due microwave excitation of fly ash. The thermal-acoustic response was successfully employed for this purpose but the thermal-elastic response was too weak to yield a useful on-line device.

  9. Measurement of transmission loss characteristics using acoustic intensity techniques at the KU-FRL Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

    Roskam, J.

    1983-01-01

    The transmission loss characteristics of panels using the acoustic intensity technique is presented. The theoretical formulation, installation of hardware, modifications to the test facility, and development of computer programs and test procedures are described. A listing of all the programs is also provided. The initial test results indicate that the acoustic intensity technique is easily adapted to measure transmission loss characteristics of panels. Use of this method will give average transmission loss values. The fixtures developed to position the microphones along the grid points are very useful in plotting the intensity maps of vibrating panels.

  10. Ultrasonic technique for monitoring of liquid density variations.

    PubMed

    Kazys, R; Rekuviene, R; Sliteris, R; Mazeika, L; Zukauskas, E

    2015-01-01

    A novel ultrasonic measurement technique for density measurements of different liquids in extreme conditions has been developed. The proposed density measurement method is based on transformation of the acoustic impedance of the measured liquid. The higher accuracy of measurements is achieved by means of the λ/4 acoustic matching layer between the load and the ultrasonic waveguide transducer. Introduction of the matching layer enhances sensitivity of the measurement system. Sometimes, the density measurements must be performed in very complex conditions: high temperature (up to 200 °C), pressure (up to 10 MPa), and high chemical activity of the medium under measurement. In this case, the special geometry metal waveguides are proposed to use in order to protect the piezoelectric transducer surface from influence of a high temperature. The experimental set-up of technique was calibrated using the reference liquids with different densities: ethyl ether, ethyl alcohol, distilled water, and different concentration (20%, 40%, and 60%) sugar-water solutions. The uncertainty of measurements is less than 1%. The proposed measurement method was verified in real conditions by monitoring the density of a melted polypropylene during manufacturing process.

  11. Acoustic emission (AE) health monitoring of diaphragm type couplings using neural network analysis

    NASA Astrophysics Data System (ADS)

    Godinez-Azcuaga, Valery F.; Shu, Fong; Finlayson, Richard D.; O'Donnell, Bruce

    2005-05-01

    This paper presents the latest results obtained from Acoustic Emission (AE) monitoring and detection of cracks and/or damage in diaphragm couplings, which are used in some aircraft and engine drive systems. Early detection of mechanical failure in aircraft drive train components is a key safety and economical issue with both military and civil sectors of aviation. One of these components is the diaphragm-type coupling, which has been evaluated as the ideal drive coupling for many application requirements such as high speed, high torque, and non-lubrication. Its flexible axial and angular displacement capabilities have made it indispensable for aircraft drive systems. However, diaphragm-type couplings may develop cracks during their operation. The ability to monitor, detect, identify, and isolate coupling cracks on an operational aircraft system is required in order to provide sufficient advance warning to preclude catastrophic failure. It is known that metallic structures generate characteristic Acoustic Emission (AE) during crack growth/propagation cycles. This phenomenon makes AE very attractive among various monitoring techniques for fault detection in diaphragm-type couplings. However, commercially available systems capable of automatic discrimination between signals from crack growth and normal mechanical noise are not readily available. Positive classification of signals requires experienced personnel and post-test data analysis, which tend to be a time-consuming, laborious, and expensive process. With further development of automated classifiers, AE can become a fully autonomous fault detection technique requiring no human intervention after implementation. AE has the potential to be fully integrated with automated query and response mechanisms for system/process monitoring and control.

  12. Final Report: Guided Acoustic Wave Monitoring of Corrosion in Recovery Boiler Tubing

    SciTech Connect

    Chinn, D J; Quarry, M J; Rose, J L

    2005-03-31

    Corrosion of tubing used in black-liquor recovery boilers is a major concern in all pulp and paper mills. Extensive corrosion in recovery boiler tubes can result in a significant safety and environmental hazard. Considerable plant resources are expended to inspect recovery boiler tubing. Currently, visual and ultrasonic inspections are primarily used during the annual maintenance shutdown to monitor corrosion rates and cracking of tubing. This Department of Energy, Office of Industrial Technologies project is developing guided acoustic waves for use on recovery boiler tubing. The feature of this acoustic technique is its cost-effectiveness in inspecting long lengths of tubes from a single inspection point. A piezoelectric or electromagnetic transducer induces guided waves into the tubes. The transducer detects fireside defects from the cold side or fireside of the tube. Cracking and thinning on recovery boiler tubes have been detected with this technique in both laboratory and field applications. This technique appears very promising for recovery boiler tube application, potentially expediting annual inspection of tube integrity.

  13. Acoustic monitoring system to quantify ingestive behavior of free-grazing cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methods to estimate intake in grazing livestock include using markers, visual observation, mechanical sensors that respond to jaw movement and acoustic recording. In most of the acoustic monitoring studies, the microphone is inverted on the forehead of the grazing livestock and the skull is utilize...

  14. Punch stretching process monitoring using acoustic emission signal analysis. II - Application of frequency domain deconvolution

    NASA Technical Reports Server (NTRS)

    Liang, Steven Y.; Dornfeld, David A.; Nickerson, Jackson A.

    1987-01-01

    The coloring effect on the acoustic emission signal due to the frequency response of the data acquisition/processing instrumentation may bias the interpretation of AE signal characteristics. In this paper, a frequency domain deconvolution technique, which involves the identification of the instrumentation transfer functions and multiplication of the AE signal spectrum by the inverse of these system functions, has been carried out. In this way, the change in AE signal characteristics can be better interpreted as the result of the change in only the states of the process. Punch stretching process was used as an example to demonstrate the application of the technique. Results showed that, through the deconvolution, the frequency characteristics of AE signals generated during the stretching became more distinctive and can be more effectively used as tools for process monitoring.

  15. Contactless optoelectronic technique for monitoring epoxy cure.

    PubMed

    Cusano, A; Buonocore, V; Breglio, G; Calabrò, A; Giordano, M; Cutolo, A; Nicolais, L

    2000-03-01

    We describe a novel noninvasive optical technique to monitor the refractive-index variation in an epoxy-based resin that is due to the polymerization process. This kind of resin is widely used in polymer matrix composites. It is well known that the process of fabricating a thermoset-based composite involves mass and heat transfer coupled with irreversible chemical reactions that induce physical changes. To improve the quality and the reliability of these materials, monitoring the cure and optimization of the manufacturing process are of key importance. We discuss the basic operating principles of an optical system based on angle deflection measurements and present typical cure-monitoring results obtained from optical characterization. The method provides a flexible, high-sensitivity, material-independent, low-cost, noninvasive tool for monitoring real-time refractive-index variation.

  16. Passive acoustic monitoring of Cook Inlet beluga whales (Delphinapterus leucas).

    PubMed

    Lammers, Marc O; Castellote, Manuel; Small, Robert J; Atkinson, Shannon; Jenniges, Justin; Rosinski, Anne; Oswald, Julie N; Garner, Chris

    2013-09-01

    The endangered beluga whale (Delphinapterus leucas) population in Cook Inlet, AK faces threats from a variety of anthropogenic factors, including coastal development, oil and gas exploration, vessel traffic, and military activities. To address existing gaps in understanding about the occurrence of belugas in Cook Inlet, a project was developed to use passive acoustic monitoring to document the year-round distribution of belugas, as well as killer whales (Orcinus orca), which prey on belugas. Beginning in June 2009, ten moorings were deployed throughout the Inlet and refurbished every two to eight months. Despite challenging conditions consisting of strong tidal currents carrying debris and seasonal ice cover, 83% of mooring deployments were successfully recovered. Noise from water flow, vessel traffic, and/or industrial activities was present at several sites, potentially masking some signals. However, belugas were successfully detected at multiple locations. Detections were relatively common in the upper inlet and less common or absent at middle and lower inlet locations. Killer whale signals were also recorded. Some seasonal variability in the occurrence of both belugas and killer whales was evident.

  17. Acoustical method of whole-body hydration status monitoring

    NASA Astrophysics Data System (ADS)

    Sarvazyan, A. P.; Tsyuryupa, S. N.; Calhoun, M.; Utter, A.

    2016-07-01

    An acoustical handheld hydration monitor (HM) for assessing the water balance of the human body was developed. Dehydration is a critical public health problem. Many elderly over age of 65 are particularly vulnerable as are infants and young children. Given that dehydration is both preventable and reversible, the need for an easy-to-perform method for the detection of water imbalance is of the utmost clinical importance. The HM is based on an experimental fact that ultrasound velocity in muscle is a linear function of water content and can be referenced to the hydration status of the body. Studies on the validity of HM for the assessment of whole-body hydration status were conducted in the Appalachian State University, USA, on healthy young adults and on elderly subjects residing at an assisted living facility. The HM was able to track changes in total body water during periods of acute dehydration and rehydration in athletes and day-to-day and diurnal variability of hydration in elderly. Results of human studies indicate that HM has a potential to become an efficient tool for detecting abnormal changes in the body hydration status.

  18. Passive acoustic monitoring of Cook Inlet beluga whales (Delphinapterus leucas).

    PubMed

    Lammers, Marc O; Castellote, Manuel; Small, Robert J; Atkinson, Shannon; Jenniges, Justin; Rosinski, Anne; Oswald, Julie N; Garner, Chris

    2013-09-01

    The endangered beluga whale (Delphinapterus leucas) population in Cook Inlet, AK faces threats from a variety of anthropogenic factors, including coastal development, oil and gas exploration, vessel traffic, and military activities. To address existing gaps in understanding about the occurrence of belugas in Cook Inlet, a project was developed to use passive acoustic monitoring to document the year-round distribution of belugas, as well as killer whales (Orcinus orca), which prey on belugas. Beginning in June 2009, ten moorings were deployed throughout the Inlet and refurbished every two to eight months. Despite challenging conditions consisting of strong tidal currents carrying debris and seasonal ice cover, 83% of mooring deployments were successfully recovered. Noise from water flow, vessel traffic, and/or industrial activities was present at several sites, potentially masking some signals. However, belugas were successfully detected at multiple locations. Detections were relatively common in the upper inlet and less common or absent at middle and lower inlet locations. Killer whale signals were also recorded. Some seasonal variability in the occurrence of both belugas and killer whales was evident. PMID:23968047

  19. Hydraulic Fracturing of Heterogeneous Rock Monitored by Acoustic Emission

    NASA Astrophysics Data System (ADS)

    Stanchits, Sergey; Burghardt, Jeffrey; Surdi, Aniket

    2015-11-01

    In this paper, the results of laboratory studies of hydraulic fracture in homogeneous sandstone blocks with man-made interfaces and heterogeneous shale blocks with weak natural interfaces are reported. Tests were conducted under similar stress conditions, with fluids of different viscosity and at different injection rates. The measurements and analysis allows the identification of fracture initiation and behavior. Fracturing with high-viscosity fluids resulted in stable fracture propagation initiated before breakdown, while fracturing with low-viscosity fluids resulted in unstable fracture propagation initiated almost simultaneously with breakdown. Analysis also allows us to measure the fluid volume entering the fracture and the fracture volume. Monitoring of acoustic emission hypocenter localizations, indicates the development of created fractured area including the intersection with interfaces, fluid propagation along interfaces, crossing interfaces, and approaching the boundaries of the block. We observe strong differences in hydraulic fracture behavior, fracture geometry and fracture propagation speed, when fracturing with water and high-viscosity fluids. We also observed distinct differences between sandstone blocks and shale blocks, when a certain P-wave velocity ray path is intersected by the hydraulic fracture. The velocity increases in sandstones and decreases in shale.

  20. Field performance of an acoustic scour-depth monitoring system

    USGS Publications Warehouse

    Mason, Jr., Robert R.; Sheppard, D. Max

    1994-01-01

    The Herbert C. Bonner Bridge over Oregon Inlet serves as the only land link between Bodie and Hatteras Islands, part of the Outer Banks of North Carolina. Periodic soundings over the past 30 years have documented channel migration, local scour, and deposition at several pilings that support the bridge. In September 1992, a data-collection system was installed to permit the off-site monitoring of scour at 16 bridge pilings. The system records channel-bed elevations at 15-minute intervals and transmits the data to a satellite receiver. A cellular phone connection also permits downloading and reviewing of the data as they are being collected. A digitally recording, acoustic fathometer is the main component of the system. In November 1993, current velocity, water-surface elevation, wave characteristics, and water temperature measuring instruments were also deployed at the site. Several performance problems relating to the equipment and to the harsh marine environment have not been resolved, but the system has collected and transmitted reliable scour-depth and water-level data.

  1. Acoustic monitoring of gas emissions from the seafloor. Part I: quantifying the volumetric flow of bubbles

    NASA Astrophysics Data System (ADS)

    Leblond, Isabelle; Scalabrin, Carla; Berger, Laurent

    2014-09-01

    Three decades of continuous ocean exploration have led us to identify subsurface fluid related processes as a key phenomenon in marine earth science research. The number of seep areas located on the seafloor has been constantly increasing with the use of multi-scale imagery techniques. Due to recent advances in transducer technology and computer processing, multibeam echosounders are now commonly used to detect submarine gas seeps escaping from the seafloor into the water column. A growing number of en- route surveys shows that sites of gas emissions escaping from the seafloor are much more numerous than previously thought. Estimating the temporal variability of the gas flow rate and volumes escaping from the seafloor has thus become a challenge of relevant interest which could be addressed by sea-floor continuous acoustic monitoring. Here, we investigate the feasibility of estimating the volumetric flow rates of gas emissions from horizontal backscattered acoustic signals. Different models based on the acoustic backscattering theory of bubbles are presented. The forward volume backscattering strength and the inversion volumetric flow rate solutions were validated with acoustic measurements from artificial gas flow rates generated in controlled sea-water tank experiments. A sensitivity analysis was carried out to investigate the behavior of the 120-kHz forward solution with respect to model input parameters (horizontal distance between transducer and bubble stream, bubble size distribution and ascent rate). The most sensitive parameter was found to be the distance of the bubble stream which can affect the volume backscattering strength by 20 dB within the horizontal range of 0-200 m. Results were used to derive the detection probability of a bubble stream for a given volume backscattering strength threshold according to different bubble flow rates and horizontal distance.

  2. Near-real-time acoustic monitoring of beaked whales and other cetaceans using a Seaglider™.

    PubMed

    Klinck, Holger; Mellinger, David K; Klinck, Karolin; Bogue, Neil M; Luby, James C; Jump, William A; Shilling, Geoffrey B; Litchendorf, Trina; Wood, Angela S; Schorr, Gregory S; Baird, Robin W

    2012-01-01

    In most areas, estimating the presence and distribution of cryptic marine mammal species, such as beaked whales, is extremely difficult using traditional observational techniques such as ship-based visual line transect surveys. Because acoustic methods permit detection of animals underwater, at night, and in poor weather conditions, passive acoustic observation has been used increasingly often over the last decade to study marine mammal distribution, abundance, and movements, as well as for mitigation of potentially harmful anthropogenic effects. However, there is demand for new, cost-effective tools that allow scientists to monitor areas of interest autonomously with high temporal and spatial resolution in near-real time. Here we describe an autonomous underwater vehicle--a glider--equipped with an acoustic sensor and onboard data processing capabilities to passively scan an area for marine mammals in near-real time. The glider was tested extensively off the west coast of the Island of Hawai'i, USA. The instrument covered approximately 390 km during three weeks at sea and collected a total of 194 h of acoustic data. Detections of beaked whales were successfully reported to shore in near-real time. Manual analysis of the recorded data revealed a high number of vocalizations of delphinids and sperm whales. Furthermore, the glider collected vocalizations of unknown origin very similar to those made by known species of beaked whales. The instrument developed here can be used to cost-effectively screen areas of interest for marine mammals for several months at a time. The near-real-time detection and reporting capabilities of the glider can help to protect marine mammals during potentially harmful anthropogenic activities such as seismic exploration for sub-sea fossil fuels or naval sonar exercises. Furthermore, the glider is capable of under-ice operation, allowing investigation of otherwise inaccessible polar environments that are critical habitats for many

  3. Near-real-time acoustic monitoring of beaked whales and other cetaceans using a Seaglider™.

    PubMed

    Klinck, Holger; Mellinger, David K; Klinck, Karolin; Bogue, Neil M; Luby, James C; Jump, William A; Shilling, Geoffrey B; Litchendorf, Trina; Wood, Angela S; Schorr, Gregory S; Baird, Robin W

    2012-01-01

    In most areas, estimating the presence and distribution of cryptic marine mammal species, such as beaked whales, is extremely difficult using traditional observational techniques such as ship-based visual line transect surveys. Because acoustic methods permit detection of animals underwater, at night, and in poor weather conditions, passive acoustic observation has been used increasingly often over the last decade to study marine mammal distribution, abundance, and movements, as well as for mitigation of potentially harmful anthropogenic effects. However, there is demand for new, cost-effective tools that allow scientists to monitor areas of interest autonomously with high temporal and spatial resolution in near-real time. Here we describe an autonomous underwater vehicle--a glider--equipped with an acoustic sensor and onboard data processing capabilities to passively scan an area for marine mammals in near-real time. The glider was tested extensively off the west coast of the Island of Hawai'i, USA. The instrument covered approximately 390 km during three weeks at sea and collected a total of 194 h of acoustic data. Detections of beaked whales were successfully reported to shore in near-real time. Manual analysis of the recorded data revealed a high number of vocalizations of delphinids and sperm whales. Furthermore, the glider collected vocalizations of unknown origin very similar to those made by known species of beaked whales. The instrument developed here can be used to cost-effectively screen areas of interest for marine mammals for several months at a time. The near-real-time detection and reporting capabilities of the glider can help to protect marine mammals during potentially harmful anthropogenic activities such as seismic exploration for sub-sea fossil fuels or naval sonar exercises. Furthermore, the glider is capable of under-ice operation, allowing investigation of otherwise inaccessible polar environments that are critical habitats for many

  4. Near-Real-Time Acoustic Monitoring of Beaked Whales and Other Cetaceans Using a Seaglider™

    PubMed Central

    Klinck, Holger; Mellinger, David K.; Klinck, Karolin; Bogue, Neil M.; Luby, James C.; Jump, William A.; Shilling, Geoffrey B.; Litchendorf, Trina; Wood, Angela S.; Schorr, Gregory S.; Baird, Robin W.

    2012-01-01

    In most areas, estimating the presence and distribution of cryptic marine mammal species, such as beaked whales, is extremely difficult using traditional observational techniques such as ship-based visual line transect surveys. Because acoustic methods permit detection of animals underwater, at night, and in poor weather conditions, passive acoustic observation has been used increasingly often over the last decade to study marine mammal distribution, abundance, and movements, as well as for mitigation of potentially harmful anthropogenic effects. However, there is demand for new, cost-effective tools that allow scientists to monitor areas of interest autonomously with high temporal and spatial resolution in near-real time. Here we describe an autonomous underwater vehicle – a glider – equipped with an acoustic sensor and onboard data processing capabilities to passively scan an area for marine mammals in near-real time. The glider was tested extensively off the west coast of the Island of Hawai'i, USA. The instrument covered approximately 390 km during three weeks at sea and collected a total of 194 h of acoustic data. Detections of beaked whales were successfully reported to shore in near-real time. Manual analysis of the recorded data revealed a high number of vocalizations of delphinids and sperm whales. Furthermore, the glider collected vocalizations of unknown origin very similar to those made by known species of beaked whales. The instrument developed here can be used to cost-effectively screen areas of interest for marine mammals for several months at a time. The near-real-time detection and reporting capabilities of the glider can help to protect marine mammals during potentially harmful anthropogenic activities such as seismic exploration for sub-sea fossil fuels or naval sonar exercises. Furthermore, the glider is capable of under-ice operation, allowing investigation of otherwise inaccessible polar environments that are critical habitats for many

  5. Real-Time Debonding Monitoring of Composite Repaired Materials via Electrical, Acoustic, and Thermographic Methods

    NASA Astrophysics Data System (ADS)

    Grammatikos, S. A.; Kordatos, E. Z.; Matikas, T. E.; Paipetis, A. S.

    2014-01-01

    The electrical properties of composite materials have been thoroughly investigated recently for the detection and monitoring of damage in carbon fiber-reinforced polymers (CFRPs) under mechanical loading. Carbon nanotubes are incorporated in the polymer matrix of CFRPs for the enhancement of their electrical properties. The electrical properties have shown to be sensitive to the damage state of the material and hence their monitoring provides the profile of their structural deterioration. The aim of the paper is the cross-validation and benchmarking of an electrical potential change monitoring (EPCM) technique against acoustic emission (AE) and lock-in thermography (LT). All techniques successfully identified damage and its propagation. Thermography was more efficient in quantifying damage and describing dynamically the debond topology, as it provided full 2D imaging of the debond in real time. EPCM was successful in providing quantitative information on debond propagation and its directionality. AE provided consistent information on damage propagation. All techniques identified three stages in the fatigue life of the interrogated coupons. The representation of the fatigue behavior as a function of life fraction, the correlation of AE data with EPCM and LT data, and most importantly the consistent behavior of all tested coupons allowed for both the direct and indirect cross-correlation of all employed methodologies, which consistently identified all aforementioned fatigue life stages.

  6. C-Coupon Studies of SiC/SiC Composites. Part 1; Acoustic Emission Monitoring

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Hurwitz, Frances I.; Calomino, Anthony M.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Modal acoustic emission (AE) was used to monitor the acoustic activity during room temperature and elevated temperature c-coupon tests for a variety of SiC/SiC systems including composites containing Sylramic (trademark), ZMI (trademark), or Hi-Nicalon (trademark) fibers with melt-infiltrated or polymer-infiltrated SiC matrices. Modal AE proved excellent at monitoring matrix cracking in the curved portion of the C-coupon specimen with increasing load. This included the load at which the first AE event occurred and the location of AE events during the test that were, presumably, caused by the formation and growth of interlaminar cracks and, at higher loads, transverse cracks. Graphical techniques were employed to estimate the load for first AE. It was determined that for this test with these material systems, the first AE could be estimated within the load range bounded by the load at which initial deviation from linearity of the load-displacement curve occurs and the load where the 98% offset of the linear regression fit intercepted the load-displacement curve. The calculation of interlaminar tensile (ILT) stress from the load for first AE was determined for all the systems. Ultimate ILT strength usually corresponded to ILT stress determined from the ultimate load to failure of the C-coupon test, which was considerably higher than the first cracking stress.

  7. Monitoring accelerated carbonation on standard Portland cement mortar by nonlinear resonance acoustic test

    NASA Astrophysics Data System (ADS)

    Eiras, J. N.; Kundu, T.; Popovics, J. S.; Monzó, J.; Borrachero, M. V.; Payá, J.

    2015-03-01

    Carbonation is an important deleterious process for concrete structures. Carbonation begins when carbon dioxide (CO2) present in the atmosphere reacts with portlandite producing calcium carbonate (CaCO3). In severe carbonation conditions, C-S-H gel is decomposed into silica gel (SiO2.nH2O) and CaCO3. As a result, concrete pore water pH decreases (usually below 10) and eventually steel reinforcing bars become unprotected from corrosion agents. Usually, the carbonation of the cementing matrix reduces the porosity, because CaCO3 crystals (calcite and vaterite) occupy more volume than portlandite. In this study, an accelerated carbonation-ageing process is conducted on Portland cement mortar samples with water to cement ratio of 0.5. The evolution of the carbonation process on mortar is monitored at different levels of ageing until the mortar is almost fully carbonated. A nondestructive technique based on nonlinear acoustic resonance is used to monitor the variation of the constitutive properties upon carbonation. At selected levels of ageing, the compressive strength is obtained. From fractured surfaces the depth of carbonation is determined with phenolphthalein solution. An image analysis of the fractured surfaces is used to quantify the depth of carbonation. The results from resonant acoustic tests revealed a progressive increase of stiffness and a decrease of material nonlinearity.

  8. A portable Raman acoustic levitation spectroscopic system for the identification and environmental monitoring of algal cells.

    PubMed

    Wood, Bayden R; Heraud, Philip; Stojkovic, Slobodanka; Morrison, Danielle; Beardall, John; McNaughton, Don

    2005-08-01

    We report the coupling of a portable Raman spectrometer to an acoustic levitation device to enable environmental monitoring and the potential taxonomic identification of microalgae. Spectra of living cells were recorded at 785 nm using a fiber-optic probe coupled to a portable Raman spectrometer. The spectra exhibit an excellent signal-to-noise ratio and clearly show bands from chlorophyll a and beta-carotene. Spectra of levitated photobleached microalgae clearly show a reduction in chlorophyll a concentration relative to beta-carotene after 10 min of exposure to a quartz halogen lamp. Spectra recorded from levitated nitrogen-limited cells also show a significant reduction in bands associated with chlorophyll a, as compared to nitrogen-replete cells. To investigate the diagnostic capability of the technique, four species of microalgae were analyzed. Good quality spectra of all four species were obtained showing varying ratios of beta-carotene to chlorophyll. The combination of an acoustic levitation device and a portable Raman spectrometer shows potential as a taxonomic and environmental monitoring tool with direct application to field studies in remote environments. PMID:16053309

  9. Laser tattoo removal as an ablation process monitored by acoustical and optical methods

    NASA Astrophysics Data System (ADS)

    Cencič, Boris; Gregorčič, Peter; Možina, Janez; Jezeršek, Matija

    2013-07-01

    Strength of the laser-tissue interaction varies even within a single tattoo because of the inhomogeneous distribution of the tattoo pigment embedded in the skin. A monitoring system is therefore developed for simultaneous monitoring of the laser tattoo removal process based on acoustical and optical techniques. A laser-beam-deflection probe is used for measuring the acoustical signals accompanying the breakdown, and a CCD camera captures the level and the spatial distribution of the plasma radiation. Using these methods we examine the degree of excitation-pulse absorption within the pigment and the degree of the structural changes of the skin. A Nd:YAG laser with a top-hat beam profile, designed for tattoo removal, is used as the excitation source in our experiments. Special attention is given to structural changes in the skin, which depend on the applied fluence. Tattoo removal with multiple pulses is also analyzed. Experiments are made in vitro (skin phantoms) and ex vivo (marking tattoos on the pig skin). The presented results are important for the understanding and optimization of the process used in medical therapies.

  10. Monitoring of tissue coagulation during thermotherapy using optoacoustic technique

    NASA Astrophysics Data System (ADS)

    Larin, Kirill V.; Larina, Irina V.; Esenaliev, Rinat O.

    2005-08-01

    In this paper we have applied the laser optoacoustic technique for real time noninvasive monitoring of thermal damage in tissues. Changes in tissue optical properties during coagulation were detected by measuring and analysing amplitude and temporal characteristics of optoacoustic signals. Coagulation of liver, myocardium and prostate was induced by interstitial continuous wave Nd : YAG laser irradiation of the samples or by conductive heating. Real time detection of thermally-induced changes in optical properties was performed with sensitive wide-band acoustic transducers. Combination of optoacoustic and diffuse reflectance technique was applied for determination of tissue optical properties: effective attenuation, total diffuse reflectance, reduced scattering coefficient and absorption coefficient. The optical properties did not change up to temperature of coagulation (about 53°C) and sharply increased during heating up to 70°C. Monitoring of the expansion of interstitial coagulation front within freshly excised canine tissues was performed in real time with spatial resolution of about 0.6 mm. The results of our study suggest that this technique can potentially be used for real time precise thermotherapy of malignant and benign lesions at depths of the order of the centimetre.

  11. On-line structural integrity monitoring and defect diagnosis of steam generators using analysis of guided acoustic waves

    NASA Astrophysics Data System (ADS)

    Lu, Baofu

    2005-11-01

    Integrity monitoring and flaw diagnostics of flat beams and tubular structures was investigated in this research using guided acoustic signals. The primary objective was to study the feasibility of using imbedded sensors for monitoring steam generator and heat exchanger tubing. A piezo-sensor suite was deployed to activate and collect Lamb wave signals that propagate along metallic specimens. The dispersion curves of Lamb waves along plate and tubular structures were generated through numerical analysis. Several advanced techniques were explored to extract representative features from acoustic time series. Among them, the Hilbert-Huang transform (HHT) is a recently developed technique for the analysis of non-linear and transient signals. A moving window method was introduced to generate the local peak characters from acoustic time series, and a zooming window technique was developed to localize the structural flaws. The dissertation presents the background of the analysis of acoustic signals acquired from piezo-electric transducers for structural defect monitoring. A comparison of the use of time-frequency techniques, including the Hilbert-Huang transform, is presented. It also presents the theoretical study of Lamb wave propagation in flat beams and tubular structures, and the need for mode separation in order to effectively perform defect diagnosis. The results of an extensive experimental study of detection, location, and isolation of structural defects in flat aluminum beams and brass tubes are presented. The time-frequency analysis and pattern recognition techniques were combined for classifying structural defects in brass tubes. Several types of flaws in brass tubes were tested, both in the air and in water. The techniques also proved to be effective under background/process noise. A detailed theoretical analysis of Lamb wave propagation was performed and simulations were carried out using the finite element software system ABAQUS. This analytical study

  12. Health Monitoring of Composite Material Structures using a Vibrometry Technique

    NASA Technical Reports Server (NTRS)

    Schulz, Mark J.

    1997-01-01

    Large composite material structures such as aircraft and Reusable Launch Vehicles (RLVS) operate in severe environments comprised of vehicle dynamic loads, aerodynamic loads, engine vibration, foreign object impact, lightning strikes, corrosion, and moisture absorption. These structures are susceptible to damage such as delamination, fiber breaking/pullout, matrix cracking, and hygrothermal strain. To ensure human safety and load-bearing integrity, these structures must be inspected to detect and locate often invisible damage and faults before becoming catastrophic. Moreover, nearly all future structures will need some type of in-service inspection technique to increase their useful life and reduce maintenance and overall costs. Possible techniques for monitoring the health and indicating damage on composite structures include: c-scan, thermography, acoustic emissions using piezoceramic actuators or fiber-optic wires with gratings, laser ultrasound, shearography, holography, x-ray, and others. These techniques have limitations in detecting damage that is beneath the surface of the structure, far away from a sensor location, or during operation of the vehicle. The objective of this project is to develop a more global method for damage detection that is based on structural dynamics principles, and can inspect for damage when the structure is subjected to vibratory loads to expose faults that may not be evident by static inspection. A Transmittance Function Monitoring (TFM) method is being developed in this project for ground-based inspection and operational health monitoring of large composite structures as a RLV. A comparison of the features of existing health monitoring approaches and the proposed TFM method is given.

  13. Continuous wide area monitoring of fish shoaling behavior with acoustic waveguide sensing and bioclutter implications

    NASA Astrophysics Data System (ADS)

    Makris, Nicholas C.; Ratilal, Purnima; Symonds, Deanelle T.; Nero, Redwood W.

    2001-05-01

    Field measurements are used to show that the detailed behavior of fish shoals can be continuously monitored at roughly 1-min intervals over wide areas spanning hundreds of square kilometers by long range acoustic waveguide sensing. The technique was used on the New Jersey Continental Shelf to produce unprecedented video images of shoal formation, fragmentation, and migration. Simultaneous line-transect measurements show the imaged shoals to contain pelagic fish with densities of at least one individual per meter3. The technique relies upon acoustic waveguide propagation in the continental shelf. Here, trapped modes dominate propagation and suffer only cylindrical spreading loss rather than the spherical loss suffered in free-space transmission or short-range propagation in the ocean. In contrast, standard methods for fish surveyance involve line transect measurements from slow moving research vessels that significantly under-sample fish distributions in time and space, leaving an incomplete behavioral picture. The implications of this bioclutter phenomenon on the Navy's long range active sonar operations in continental shelf environments are discussed.

  14. Accumulated damage process of thermal sprayed coating under rolling contact by acoustic emission technique

    NASA Astrophysics Data System (ADS)

    Xu, Jia; Zhou, Zhen-yu; Piao, Zhong-yu

    2016-09-01

    The accumulated damage process of rolling contact fatigue (RCF) of plasma-sprayed coatings was investigated. The influences of surface roughness, loading condition, and stress cycle frequency on the accumulated damage status of the coatings were discussed. A ball-ondisc machine was employed to conduct RCF experiments. Acoustic emission (AE) technique was introduced to monitor the RCF process of the coatings. AE signal characteristics were investigated to reveal the accumulated damage process. Result showed that the polished coating would resist the asperity contact and remit accumulated damage. The RCF lifetime would then extend. Heavy load would aggravate the accumulated damage status and induce surface fracture. Wear became the main failure mode that reduced the RCF lifetime. Frequent stress cycle would aggravate the accumulated damage status and induce interface fracture. Fatigue then became the main failure mode that also reduced the RCF lifetime.

  15. Accumulated damage process of thermal sprayed coating under rolling contact by acoustic emission technique

    NASA Astrophysics Data System (ADS)

    Xu, Jia; Zhou, Zhen-yu; Piao, Zhong-yu

    2016-07-01

    The accumulated damage process of rolling contact fatigue (RCF) of plasma-sprayed coatings was investigated. The influences of surface roughness, loading condition, and stress cycle frequency on the accumulated damage status of the coatings were discussed. A ball-ondisc machine was employed to conduct RCF experiments. Acoustic emission (AE) technique was introduced to monitor the RCF process of the coatings. AE signal characteristics were investigated to reveal the accumulated damage process. Result showed that the polished coating would resist the asperity contact and remit accumulated damage. The RCF lifetime would then extend. Heavy load would aggravate the accumulated damage status and induce surface fracture. Wear became the main failure mode that reduced the RCF lifetime. Frequent stress cycle would aggravate the accumulated damage status and induce interface fracture. Fatigue then became the main failure mode that also reduced the RCF lifetime.

  16. Analysis Techniques of Acoustic Emission Data for Damage Assessment of Reinforced Concrete Structures

    NASA Astrophysics Data System (ADS)

    Garilli, G.; Proverbio, E.; Marino, A.; de Domenico, D.; Termini, D.; Teramo, A.

    2010-12-01

    The aim of this work is the arrangement, through Acoustics Emission (AE) techniques, of a procedure aimed at early diagnosis of building diseases with the assessment of the causes that have produced a crack in a given structural element, in order to plan suitable structural adjustment works. To this end, bending tests were performed, divided into different cycles of increasing load on a concrete beam, to assess the damage level and response in relation to the stress change. Through the proposed procedure and different indicators of the damage level of material, such as b, Ib and Z-value, it was possible to identify in the study sample areas where cracks were detected, assessing the size, evolution process typology of microcraks. The recorded parameters of AE (Counts, Amplitude) are well related to the damage extent and applied load, providing a significant validation of the reliability analysis procedures used for monitoring and early detection of building diseases.

  17. Seismic augmentation of acoustic monitoring of mortar fire

    NASA Astrophysics Data System (ADS)

    Anderson, Thomas S.

    2007-10-01

    The US Army Corps of Engineers Research and Development Center participated in a joint ARL-NATO TG-53 field experiment and data collect at Yuma Proving Ground, AZ in early November 2005. Seismic and acoustic signatures from both muzzle blasts and impacts of small arms fire and artillery were recorded using 7 seismic arrays and 3 acoustic arrays. Arrays comprised of 12 seismic and 12 acoustic sensors each were located from 700 m to 18 km from gun positions. Preliminary analysis of signatures attributed to 60mm, 81mm, 120 mm mortars recorded at a seismic-acoustic array 1.1 km from gun position are presented. Seismic and acoustic array f-k analysis is performed to detect and characterize the source signature. Horizontal seismic data are analyzed to determine efficacy of a seismic discriminant for mortar and artillery sources. Rotation of North and East seismic components to radial and transverse components relative to the source-receiver path provide maximum surface wave amplitude on the transverse component. Angles of rotation agree well with f-k analysis of both seismic and acoustic signals. The spectral energy of the rotated transverse surface wave is observable on the all caliber of mortars at a distance of 1.1 km and is a reliable source discriminant for mortar sources at this distance. In a step towards automation, travel time stencils using local seismic and acoustic velocities are applied to seismic data for analysis and determination of source characteristics.

  18. Surface Acoustic Wave Monitor for Deposition and Analysis of Ultra-Thin Films

    NASA Technical Reports Server (NTRS)

    Hines, Jacqueline H. (Inventor)

    2015-01-01

    A surface acoustic wave (SAW) based thin film deposition monitor device and system for monitoring the deposition of ultra-thin films and nanomaterials and the analysis thereof is characterized by acoustic wave device embodiments that include differential delay line device designs, and which can optionally have integral reference devices fabricated on the same substrate as the sensing device, or on a separate device in thermal contact with the film monitoring/analysis device, in order to provide inherently temperature compensated measurements. These deposition monitor and analysis devices can include inherent temperature compensation, higher sensitivity to surface interactions than quartz crystal microbalance (QCM) devices, and the ability to operate at extreme temperatures.

  19. Delineation of excessive strength soils through acoustic to seismic techniques

    NASA Astrophysics Data System (ADS)

    Howard, Wheeler B.

    Soils overlying a naturally occurring hardpans, such as a fragipan, normally experience decreased crop yield and increased erosion rates. The motivation for this work stems from the desire to map the fragipan horizon in order to judiciously distribute agricultural resources. Currently, the fragipan horizon is mapped via core samples, auger holes, cone penetrometer measurements, and trench studies. The focus of this study is the application of a/s coupling techniques, which are less invasive, potentially more expedient, and inherently sensitive to changes in mechanical properties, to determine the depth to the fragipan. Previous investigations correlated various attributes of the acoustic to seismic (a/s) signature to physical quantities of the soil. These results showed promise for characterizing the near surface distribution of the soil's mechanical properties. This work further refines the a/s coupling technique to determine the depth to the soil-fragipan interface and the mechanical properties of the soil-fragipan system. The a/s coupling signature was measured at two field sites along with seismic refraction, cone penetrometer, trench, and core sample surveys. The ground truth served as a guide for the inversion of the a/s coupling field data. A multi-layered Thompson-Haskell viscoelastic forward model was employed to model the a,/s signature of the soil. Simulations with the forward model indicated that the a/s signature behaved as a quarter wavelength resonance prior to the onset of critical angles.Significant shins in the amplitude and frequency of the a/s signature occurred as critical angles were traversed. Inversion of svnthetic data via a hybrid algorithm was successful for both one and two layers over a half-space when the shear velocity was constrained. The measured a/s and modeled a/s signatures did not agree whether using the ground truth in modeling the als signature or comparing to the results from the a/s inversion. This may be because the a/s is

  20. Innovative techniques for analyzing the three-dimensional behavioral results from acoustically tagged fish

    NASA Astrophysics Data System (ADS)

    Steig, Tracey W.; Timko, Mark A.

    2005-04-01

    Acoustic tags were used to monitor the swimming patterns of downstream migrating salmon smolts approaching various dams on the Columbia River, USA. Downstream migrating yearling chinook (Oncorhynchus tshawytscha), steelhead (Oncorhynchus mykiss), sockeye (Oncorhynchus nerka), and sub-yearling chinook smolts were surgically implanted with acoustic tags. Fish were tracked in three-dimensions as they approached and passed into the turbine intakes, spillways, and surface bypass channel entrances at the dams during the 2004 spring and summer outmigrations. A number of advances in the analysis techniques and software have been made over the past few years. Some of these improvements include the development of various fish density algorithms, stream trace modeling analysis, and advances of three-dimensional animation programs. Three-dimensional tracks of fish approaching the turbine intakes, spillways, and surface bypass channel entrances will be presented. Concentrations of fish passage will be presented as three-dimensional fish densities superimposed over dam structures. Stream trace modeling animation will be presented showing predicted fish passage routes.

  1. Remote acoustic monitoring of North Atlantic right whales (Eubalaena glacialis) reveals seasonal and diel variations in acoustic behavior.

    PubMed

    Matthews, Leanna P; McCordic, Jessica A; Parks, Susan E

    2014-01-01

    Remote acoustic monitoring is a non-invasive tool that can be used to study the distribution, behavior, and habitat use of sound-producing species. The North Atlantic right whale (Eubalaena glacialis) is an endangered baleen whale species that produces a variety of stereotyped acoustic signals. One of these signals, the "gunshot" sound, has only been recorded from adult male North Atlantic right whales and is thought to function for reproduction, either as reproductive advertisement for females or as an agonistic signal toward other males. This study uses remote acoustic monitoring to analyze the presence of gunshots over a two-year period at two sites on the Scotian Shelf to determine if there is evidence that North Atlantic right whales may use these locations for breeding activities. Seasonal analyses at both locations indicate that gunshot sound production is highly seasonal, with an increase in the autumn. One site, Roseway West, had significantly more gunshot sounds overall and exhibited a clear diel trend in production of these signals at night. The other site, Emerald South, also showed a seasonal increase in gunshot production during the autumn, but did not show any significant diel trend. This difference in gunshot signal production at the two sites indicates variation either in the number or the behavior of whales at each location. The timing of the observed seasonal increase in gunshot sound production is consistent with the current understanding of the right whale breeding season, and our results demonstrate that detection of gunshots with remote acoustic monitoring can be a reliable way to track shifts in distribution and changes in acoustic behavior including possible mating activities. PMID:24646524

  2. Remote acoustic monitoring of North Atlantic right whales (Eubalaena glacialis) reveals seasonal and diel variations in acoustic behavior.

    PubMed

    Matthews, Leanna P; McCordic, Jessica A; Parks, Susan E

    2014-01-01

    Remote acoustic monitoring is a non-invasive tool that can be used to study the distribution, behavior, and habitat use of sound-producing species. The North Atlantic right whale (Eubalaena glacialis) is an endangered baleen whale species that produces a variety of stereotyped acoustic signals. One of these signals, the "gunshot" sound, has only been recorded from adult male North Atlantic right whales and is thought to function for reproduction, either as reproductive advertisement for females or as an agonistic signal toward other males. This study uses remote acoustic monitoring to analyze the presence of gunshots over a two-year period at two sites on the Scotian Shelf to determine if there is evidence that North Atlantic right whales may use these locations for breeding activities. Seasonal analyses at both locations indicate that gunshot sound production is highly seasonal, with an increase in the autumn. One site, Roseway West, had significantly more gunshot sounds overall and exhibited a clear diel trend in production of these signals at night. The other site, Emerald South, also showed a seasonal increase in gunshot production during the autumn, but did not show any significant diel trend. This difference in gunshot signal production at the two sites indicates variation either in the number or the behavior of whales at each location. The timing of the observed seasonal increase in gunshot sound production is consistent with the current understanding of the right whale breeding season, and our results demonstrate that detection of gunshots with remote acoustic monitoring can be a reliable way to track shifts in distribution and changes in acoustic behavior including possible mating activities.

  3. Unique gel-coupled acoustic sensor array monitors human voice and physiology

    NASA Astrophysics Data System (ADS)

    Scanlon, Michael

    2002-11-01

    The health and performance of soldiers, firefighters, and other first responders in strenuous and hazardous environments can be continuously and remotely monitored with body-worn acoustic sensors. The Army Research Laboratory's gel-coupled acoustic physiological monitoring sensor has acoustic impedance properties similar to the skin that facilitate the transmission of body sounds into the sensor pad, yet significantly repel ambient airborne noises due to an impedance mismatch. Acoustic signal processing detects physiological events such as heartbeats, breaths, wheezes, coughs, blood pressure, activity, motion, and voice for communication and automatic speech recognition. Acoustic sensors can be in a helmet or in a strap around the neck, chest, and wrist. Although the physiological sounds have high SNR, the acoustic sensor also responds to motion-induced artifacts that sometimes obscure meaningful physiology. A noise-canceling sensor array configuration helps remove motion noise by using two acoustic sensors on the front sides of the neck and 2 additional acoustic sensors on each wrist. The motion noise detected on all 4 sensors will be dissimilar and out of phase, yet the physiology on all 4 sensors is covariant. Pulse wave transit time between neck and wrist will indicate systolic blood pressure. Data from a firefighter experiment will be presented.

  4. A custom acoustic emission monitoring system for harsh environments: application to freezing-induced damage in alpine rock-walls

    NASA Astrophysics Data System (ADS)

    Girard, L.; Beutel, J.; Gruber, S.; Hunziker, J.; Lim, R.; Weber, S.

    2012-06-01

    We present a custom acoustic emission (AE) monitoring system designed to perform long-term measurements on high-alpine rock-walls. AE monitoring is a common technique for characterizing damage evolution in solid materials. The system is based on a two-channel AE sensor node (AE-node) integrated into a Wireless Sensor Network (WSN) customized for operation in harsh environments. This wireless architecture offers flexibility in the deployment of AE-nodes at any position of the rock-wall that needs to be monitored, within a range of a few hundred meters from a core station connected to the internet. The system achieves near real-time data delivery and allows the user to remotely control the AE detection threshold. In order to protect AE sensors and capture acoustic signals from specific depths of the rock-wall, a special casing was developed. The monitoring system is completed by two probes that measure rock temperature and liquid water content, both probes being also integrated into the WSN. We report a first deployment of the monitoring system on a rock-wall at Jungfraujoch, 3500 m a.s.l., Switzerland. While this first deployment of the monitoring system aims to support fundamental research on processes that damage rock under cold climate, the system could serve a number of other applications, including rock-fall hazard surveillance or structural monitoring of concrete structures.

  5. A custom acoustic emission monitoring system for harsh environments: application to freezing-induced damage in alpine rock walls

    NASA Astrophysics Data System (ADS)

    Girard, L.; Beutel, J.; Gruber, S.; Hunziker, J.; Lim, R.; Weber, S.

    2012-11-01

    We present a custom acoustic emission (AE) monitoring system designed to perform long-term measurements on high-alpine rock walls. AE monitoring is a common technique for characterizing damage evolution in solid materials. The system is based on a two-channel AE sensor node (AE-node) integrated into a wireless sensor network (WSN) customized for operation in harsh environments. This wireless architecture offers flexibility in the deployment of AE-nodes at any position of the rock wall that needs to be monitored, within a range of a few hundred meters from a core station connected to the internet. The system achieves near real-time data delivery and allows the user to remotely control the AE detection threshold. In order to protect AE sensors and capture acoustic signals from specific depths of the rock wall, a special casing was developed. The monitoring system is completed by two probes that measure rock temperature and liquid water content, both probes being also integrated into the WSN. We report a first deployment of the monitoring system on a rock wall at Jungfraujoch, 3500 m a.s.l., Switzerland. While this first deployment of the monitoring system aims to support fundamental research on processes that damage rock under cold climate, the system could serve a number of other applications, including rock fall hazard surveillance or structural monitoring of concrete structures.

  6. Calibration techniques and sampling resolution requirements for groundtruthing multibeam acoustic backscatter (EM3000) and QTC VIEW™ classification technology

    NASA Astrophysics Data System (ADS)

    Sutherland, T. F.; Galloway, J.; Loschiavo, R.; Levings, C. D.; Hare, R.

    2007-12-01

    Both acoustic and sediment surveys were carried out in the Broughton Archipelago, British Columbia, in order to map a former aquaculture site and calibrate acoustic surveys with georeferenced sediment properties. The acoustic surveys included EM3000 Multibeam (including backscatter) and QTC VIEW™ (Series IV) technologies, while the geotechnical survey entailed Van Veen grab sampling of surface sediments and associated analyses. The two acoustic technologies were consistent in their ability to identify distinct regions of seafloor characterized by rock outcrops, consolidated substrates, or gel-mud depositional fields. Both multibeam backscatter data and QTC VIEW™ number-coded classifications were extracted across a range of circular areas located at each georeferenced sampling station (radii: 2, 3, 4, 5, 8, 12, 16, 20 m). Statistical correlations were observed between backscatter and certain geotechnical properties, such as sediment porosity, sediment grain size fractions (<2 μm, silt content), and particulate sulfur concentration. The areal resolution of backscatter extraction was explored in terms of determining a sensitive calibration technique between backscatter and sediment properties. In general the highest r2 values between backscatter and sediment variables were observed across extraction radii between 8 and 20 m. Such groundtruthing techniques could be used to interpolate seafloor characteristics between sampling stations and provide a steering tool for sampling designs associated with benthic monitoring programs.

  7. Assessment of error rates in acoustic monitoring with the R package monitoR

    USGS Publications Warehouse

    Katz, Jonathan; Hafner, Sasha D.; Donovan, Therese

    2016-01-01

    Detecting population-scale reactions to climate change and land-use change may require monitoring many sites for many years, a process that is suited for an automated system. We developed and tested monitoR, an R package for long-term, multi-taxa acoustic monitoring programs. We tested monitoR with two northeastern songbird species: black-throated green warbler (Setophaga virens) and ovenbird (Seiurus aurocapilla). We compared detection results from monitoR in 52 10-minute surveys recorded at 10 sites in Vermont and New York, USA to a subset of songs identified by a human that were of a single song type and had visually identifiable spectrograms (e.g. a signal:noise ratio of at least 10 dB: 166 out of 439 total songs for black-throated green warbler, 502 out of 990 total songs for ovenbird). monitoR’s automated detection process uses a ‘score cutoff’, which is the minimum match needed for an unknown event to be considered a detection and results in a true positive, true negative, false positive or false negative detection. At the chosen score cut-offs, monitoR correctly identified presence for black-throated green warbler and ovenbird in 64% and 72% of the 52 surveys using binary point matching, respectively, and 73% and 72% of the 52 surveys using spectrogram cross-correlation, respectively. Of individual songs, 72% of black-throated green warbler songs and 62% of ovenbird songs were identified by binary point matching. Spectrogram cross-correlation identified 83% of black-throated green warbler songs and 66% of ovenbird songs. False positive rates were  for song event detection.

  8. Volatile organic compound monitoring by photo acoustic radiometry

    SciTech Connect

    Sollid, J.E.; Trujillo, V.L.; Limback, S.P.; Woloshun, K.A.

    1995-12-01

    Two methods for sampling and analyzing volatile organics in subsurface pore gas were developed for use at the Hazardous Waste Disposal Site at Los Alamos National Laboratory. One is Thermal Desorption Gas Chromatography Mass Spectrometry (TDGCMS), the other is Photoacoustic Radiometry (PAR). Presented here are two years worth of experience and lessons learned as both techniques matured. The sampling technique is equally as important as the analysis method. PAR is a nondispersive infrared technique utilizing band pass filters in the region from 1 to 15 {mu}m. A commercial instrument, the Model 1302 Multigas Analyzer, made by Bruel and Kjaer, was adapted for field use. To use the PAR there must be some a priori knowledge of the constellation of analytes to be measured. The TDGCMS method is sensitive to 50 analytes. Hence TDGCMS is used in an initial survey of the site to determine what compounds are present and at what concentration. Once the major constituents of the soil-gas vapor plume are known the PAR can be configured to monitor for the five analytes of most interest. The PAR can analyse a sample in minutes, while in the field. The PAR is also quite precise in controlled situations.

  9. Real Time Monitoring of Containerless Microreactions in Acoustically Levitated Droplets via Ambient Ionization Mass Spectrometry.

    PubMed

    Crawford, Elizabeth A; Esen, Cemal; Volmer, Dietrich A

    2016-09-01

    Direct in-droplet (in stillo) microreaction monitoring using acoustically levitated micro droplets has been achieved by combining acoustic (ultrasonic) levitation for the first time with real time ambient tandem mass spectrometry (MS/MS). The acoustic levitation and inherent mixing of microliter volumes of reactants (3 μL droplets), yielding total reaction volumes of 6 μL, supported monitoring the acid-catalyzed degradation reaction of erythromycin A. This reaction was chosen to demonstrate the proof-of-principle of directly monitoring in stillo microreactions via hyphenated acoustic levitation and ambient ionization mass spectrometry. The microreactions took place completely in stillo over 30, 60, and 120 s within the containerless stable central pressure node of an acoustic levitator, thus readily promoting reaction miniaturization. For the evaluation of the miniaturized in stillo reactions, the degradation reactions were also carried out in vials (in vitro) with a total reaction volume of 400 μL. The reacted in vitro mixtures (6 μL total) were similarly introduced into the acoustic levitator prior to ambient ionization MS/MS analysis. The in stillo miniaturized reactions provided immediate real-time snap-shots of the degradation process for more accurate reaction monitoring and used a fraction of the reactants, while the larger scale in vitro reactions only yielded general reaction information. PMID:27505037

  10. Monitoring beach changes using GPS surveying techniques

    USGS Publications Warehouse

    Morton, Robert; Leach, Mark P.; Paine, Jeffrey G.; Cardoza, Michael A.

    1993-01-01

    The adaptation of Global Positioning System (GPS) surveying techniques to beach monitoring activities is a promising response to this challenge. An experiment that employed both GPS and conventional beach surveying was conducted, and a new beach monitoring method employing kinematic GPS surveys was devised. This new method involves the collection of precise shore-parallel and shore-normal GPS positions from a moving vehicle so that an accurate two-dimensional beach surface can be generated. Results show that the GPS measurements agree with conventional shore-normal surveys at the 1 cm level, and repeated GPS measurements employing the moving vehicle demonstrate a precision of better than 1 cm. In addition, the nearly continuous sampling and increased resolution provided by the GPS surveying technique reveals alongshore changes in beach morphology that are undetected by conventional shore-normal profiles. The application of GPS surveying techniques combined with the refinement of appropriate methods for data collection and analysis provides a better understanding of beach changes, sediment transport, and storm impacts.

  11. Ductile Deformation of Dehydrating Serpentinite Evidenced by Acoustic Signal Monitoring

    NASA Astrophysics Data System (ADS)

    Gasc, J.; Hilairet, N.; Wang, Y.; Schubnel, A. J.

    2012-12-01

    Serpentinite dehydration is believed to be responsible for triggering earthquakes at intermediate depths (i.e., 60-300 km) in subduction zones. Based on experimental results, some authors have proposed mechanisms that explain how brittle deformation can occur despite high pressure and temperature conditions [1]. However, reproducing microseismicity in the laboratory associated with the deformation of dehydrating serpentinite remains challenging. A recent study showed that, even for fast dehydration kinetics, ductile deformation could take place rather than brittle faulting in the sample [2]. This latter study was conducted in a multi-anvil apparatus without the ability to control differential stress during dehydration. We have since conducted controlled deformation experiments in the deformation-DIA (D-DIA) on natural serpentinite samples at sector 13 (GSECARS) of the APS. Monochromatic radiation was used with both a 2D MAR-CCD detector and a CCD camera to determine the stress and the strain of the sample during the deformation process [3]. In addition, an Acoustic Emission (AE) recording setup was used to monitor the microseismicity from the sample, using piezo-ceramic transducers glued on the basal truncation of the anvils. The use of six independent transducers allows locating the AEs and calculating the corresponding focal mechanisms. The samples were deformed at strain rates of 10-5-10-4 s-1 under confining pressures of 3-5 GPa. Dehydration was triggered during the deformation by heating the samples at rates ranging from 5 to 60 K/min. Before the onset of the dehydration, X-ray diffraction data showed that the serpentinite sustained ~1 GPa of stress which plummeted when dehydration occurred. Although AEs were recorded during the compression and decompression stages, no AEs ever accompanied this stress drop, suggesting ductile deformation of the samples. Hence, unlike many previous studies, no evidence for fluid embrittlement and anticrack generation was found

  12. A survey on acoustic signature recognition and classification techniques for persistent surveillance systems

    NASA Astrophysics Data System (ADS)

    Shirkhodaie, Amir; Alkilani, Amjad

    2012-06-01

    Application of acoustic sensors in Persistent Surveillance Systems (PSS) has received considerable attention over the last two decades because they can be rapidly deployed and have low cost. Conventional utilization of acoustic sensors in PSS spans a wide range of applications including: vehicle classification, target tracking, activity understanding, speech recognition, shooter detection, etc. This paper presents a current survey of physics-based acoustic signature classification techniques for outdoor sounds recognition and understanding. Particularly, this paper focuses on taxonomy and ontology of acoustic signatures resulted from group activities. The taxonomy and supportive ontology considered include: humanvehicle, human-objects, and human-human interactions. This paper, in particular, exploits applicability of several spectral analysis techniques as a means to maximize likelihood of correct acoustic source detection, recognition, and discrimination. Spectral analysis techniques based on Fast Fourier Transform, Discrete Wavelet Transform, and Short Time Fourier Transform are considered for extraction of features from acoustic sources. In addition, comprehensive overviews of most current research activities related to scope of this work are presented with their applications. Furthermore, future potential direction of research in this area is discussed for improvement of acoustic signature recognition and classification technology suitable for PSS applications.

  13. Lidar techniques for environmental and ecological monitoring

    NASA Astrophysics Data System (ADS)

    Svanberg, Sune

    2015-04-01

    An overview of optical probing of the atmosphere will be given, where mostly active remote- sensing techniques of the laser-radar type will be covered, but also some passive techniques employing ambient radiation. Atmospheric objects of quite varying sizes can be studied. Mercury is the only pollutant in atomic form in the atmosphere, while other pollutants are either molecular or in particle form. Light detection and ranging (Lidar) techniques allow three-dimensional mapping of such constituents, and examples from atmospheric lidar work in Lund and in Guangzhou will be given. Recently, much larger lidar targets have been studied. Monitoring of flying insects and birds is of considerable ecological interest, and several projects have been pursued in collaboration with biologists. Mostly, elastic backscattering and fluorescence techniques are employed. Some references to recent activities by the author and his colleagues are given below. [1] Z.G. Guan, L. Mei, P. Lundin, G. Somesfalean, and S. Svanberg, Vertical Lidar Sounding of Air Pollutants in a Major Chinese City, Appl. Phys. B 101, 465 (2010) [2] L. Mei, G.Y. Zhou and S. Svanberg, Differential Absorption Lidar System Employed for Background Atomic Mercury Vertical Profiling in South China, Lasers Opt. Eng. 55, 128 (2013) [3] Z.G. Guan, M. Brydegaard, P. Lundin, M. Wellenreuther, E. Svensson, and S. Svanberg, Insect Monitoring with Fluorescence LIDAR techniques - Field experiments, Appl. Optics 48, 5668 (2010) [4] A. Runemark, M. Wellereuther, H. Jayaweera, S. Svanberg and M. Brydegaard, Rare Events in Remote Dark Field Spectroscopy: An Ecological Case study of Insects, IEEE JSTQE 18, 1573 (2011) [5] L. Mei, Z.G. Guan, H.J. Zhou, J. Lv, Z.R. Zhu, J.A. Cheng, F.J. Chen, C. Löfstedt, S. Svanberg, and G. Somesfalean, Agricultural Pest Monitoring using Fluorescence Lidar Techniques, Applied Physics B 106, 733 (2011) [6] P. Lundin, P. Samuelsson, S. Svanberg, A. Runemark, S. Åkesson, and M. Brydegaard, Remote

  14. Acoustic emission source location in complex structures using full automatic delta T mapping technique

    NASA Astrophysics Data System (ADS)

    Al-Jumaili, Safaa Kh.; Pearson, Matthew R.; Holford, Karen M.; Eaton, Mark J.; Pullin, Rhys

    2016-05-01

    An easy to use, fast to apply, cost-effective, and very accurate non-destructive testing (NDT) technique for damage localisation in complex structures is key for the uptake of structural health monitoring systems (SHM). Acoustic emission (AE) is a viable technique that can be used for SHM and one of the most attractive features is the ability to locate AE sources. The time of arrival (TOA) technique is traditionally used to locate AE sources, and relies on the assumption of constant wave speed within the material and uninterrupted propagation path between the source and the sensor. In complex structural geometries and complex materials such as composites, this assumption is no longer valid. Delta T mapping was developed in Cardiff in order to overcome these limitations; this technique uses artificial sources on an area of interest to create training maps. These are used to locate subsequent AE sources. However operator expertise is required to select the best data from the training maps and to choose the correct parameter to locate the sources, which can be a time consuming process. This paper presents a new and improved fully automatic delta T mapping technique where a clustering algorithm is used to automatically identify and select the highly correlated events at each grid point whilst the "Minimum Difference" approach is used to determine the source location. This removes the requirement for operator expertise, saving time and preventing human errors. A thorough assessment is conducted to evaluate the performance and the robustness of the new technique. In the initial test, the results showed excellent reduction in running time as well as improved accuracy of locating AE sources, as a result of the automatic selection of the training data. Furthermore, because the process is performed automatically, this is now a very simple and reliable technique due to the prevention of the potential source of error related to manual manipulation.

  15. Diagnostic reasoning techniques for selective monitoring

    NASA Technical Reports Server (NTRS)

    Homem-De-mello, L. S.; Doyle, R. J.

    1991-01-01

    An architecture for using diagnostic reasoning techniques in selective monitoring is presented. Given the sensor readings and a model of the physical system, a number of assertions are generated and expressed as Boolean equations. The resulting system of Boolean equations is solved symbolically. Using a priori probabilities of component failure and Bayes' rule, revised probabilities of failure can be computed. These will indicate what components have failed or are the most likely to have failed. This approach is suitable for systems that are well understood and for which the correctness of the assertions can be guaranteed. Also, the system must be such that changes are slow enough to allow the computation.

  16. Acoustic holography: Problems associated with construction and reconstruction techniques

    NASA Technical Reports Server (NTRS)

    Singh, J. J.

    1978-01-01

    The implications of the difference between the inspecting and interrogating radiations are discussed. For real-time, distortionless, sound viewing, it is recommended that infrared radiation of wavelength comparable to the inspecting sound waves be used. The infrared images can be viewed with (IR visible) converter phosphors. The real-time display of the visible image of the acoustically-inspected object at low sound levels such as are used in medical diagnosis is evaluated. In this connection attention is drawn to the need for a phosphor screen which is such that its optical transmission at any point is directly related to the incident electron beam intensity at that point. Such a screen, coupled with an acoustical camera, can enable instantaneous sound wave reconstruction.

  17. Utilizing numerical techniques in turbofan inlet acoustic suppressor design

    NASA Astrophysics Data System (ADS)

    Baumeister, K. J.

    Numerical theories in conjunction with previously published analytical results are used to augment current analytical theories in the acoustic design of a turbofan inlet nacelle. In particular, a finite element-integral theory is used to study the effect of the inlet lip radius on the far field radiation pattern and to determine the optimum impedance in an actual engine environment. For some single mode JT15D data, the numerical theory and experiment are found to be in a good agreement.

  18. Autonomous Acoustic Receiver Deployment and Mooring Techniques for Use in Large Rivers and Estuaries

    SciTech Connect

    Titzler, P. Scott; McMichael, Geoffrey A.; Carter, Jessica A.

    2010-08-01

    Autonomous acoustic receivers are often deployed across a range of aquatic habitats to study aquatic species. The Juvenile Salmon Telemetry System autonomous acoustic receiver packages we deployed in the Columbia River and its estuary were comprised of an acoustic receiver, acoustic release, and mooring line sections and were deployed directly on the river bottom. Detection ranges and reception data from past optimization deployments helped determine acoustic receiver spacing in order to achieve acceptable detection probabilities for juvenile salmon survival estimation. Methods used in 2005, which resulted in a high equipment loss rate, were modified and used between 2006 and 2008 to increase crew safety and optimize receiver deployment and recovery operations in a large river system. By eliminating surface buoys and taglines (for anchor recovery), we experienced a recovery success rate greater than previous acoustic receiver deployment techniques used in the Columbia River and elsewhere. This autonomous acoustic receiver system has optimized deployment, recovery, and servicing efficiency to successfully detect acoustic-tagged salmonids in a variety of river environments.

  19. Acoustic-wave sensor for ambient monitoring of a photoresist-stripping agent

    DOEpatents

    Pfeifer, K.B.; Hoyt, A.E.; Frye, G.C.

    1998-08-18

    The acoustic-wave sensor is disclosed. The acoustic-wave sensor is designed for ambient or vapor-phase monitoring of a photoresist-stripping agent such as N-methylpyrrolidinone (NMP), ethoxyethylpropionate (EEP) or the like. The acoustic-wave sensor comprises an acoustic-wave device such as a surface-acoustic-wave (SAW) device, a flexural-plate-wave (FPW) device, an acoustic-plate-mode (APM) device, or a thickness-shear-mode (TSM) device (also termed a quartz crystal microbalance or QCM) having a sensing region on a surface thereof. The sensing region includes a sensing film for sorbing a quantity of the photoresist-stripping agent, thereby altering or shifting a frequency of oscillation of an acoustic wave propagating through the sensing region for indicating an ambient concentration of the agent. According to preferred embodiments of the invention, the acoustic-wave device is a SAW device; and the sensing film comprises poly(vinylacetate), poly(N-vinylpyrrolidinone), or poly(vinylphenol). 3 figs.

  20. Acoustic-wave sensor for ambient monitoring of a photoresist-stripping agent

    DOEpatents

    Pfeifer, Kent B.; Hoyt, Andrea E.; Frye, Gregory C.

    1998-01-01

    The acoustic-wave sensor. The acoustic-wave sensor is designed for ambient or vapor-phase monitoring of a photoresist-stripping agent such as N-methylpyrrolidinone (NMP), ethoxyethylpropionate (EEP) or the like. The acoustic-wave sensor comprises an acoustic-wave device such as a surface-acoustic-wave (SAW) device, a flexural-plate-wave (FPW) device, an acoustic-plate-mode (APM) device, or a thickness-shear-mode (TSM) device (also termed a quartz crystal microbalance or QCM) having a sensing region on a surface thereof. The sensing region includes a sensing film for sorbing a quantity of the photoresist-stripping agent, thereby altering or shifting a frequency of oscillation of an acoustic wave propagating through the sensing region for indicating an ambient concentration of the agent. According to preferred embodiments of the invention, the acoustic-wave device is a SAW device; and the sensing film comprises poly(vinylacetate), poly(N-vinylpyrrolidinone), or poly(vinylphenol).

  1. Measurement of liquid surface acoustic wave amplitudes using HeNe laser homodyne techniques

    NASA Astrophysics Data System (ADS)

    Hickman, G. D.; Hsu, Y. L.; Lee, M. S.; Bourgeois, B. S.; Hsieh, S. T.

    1988-01-01

    Recent results in the measurement of small amplitude acoustic waves on the water surface are presented. The research was performed using laser homodyne techniques in a small laboratory water tank. The homodyne system consists of optical, acoustic, and data acquisition subsystems. The optical subsystem includes an HeNe laser and polarizing components. THe acoustic subsystem consists of standard low power transducers and a power amplifier. The data acquisition subsystem includes a spectrum analyzer and a personal computer. Measurements were made in the acoustic frequency range of 15 - 23 kHz and sound pressure levels of 120-180 dB re 1 micropascal. It is estimated that the homodyne technique can detect surface amplitude deformations on the order of 90 A.

  2. Considerations for acoustic emission monitoring of spherical Kevlar/epoxy composite pressure vessels

    NASA Technical Reports Server (NTRS)

    Hamstad, M. A.; Patterson, R. G.

    1977-01-01

    We are continuing to research the applications of acoustic emission testing for predicting burst pressure of filament-wound Kevlar 49/epoxy pressure vessels. This study has focused on three specific areas. The first area involves development of an experimental technique and the proper instrumentation to measure the energy given off by the acoustic emission transducer per acoustic emission burst. The second area concerns the design of a test fixture in which to mount the composite vessel so that the acoustic emission transducers are held against the outer surface of the composite. Included in this study area is the calibration of the entire test setup including couplant, transducer, electronics, and the instrument measuring the energy per burst. In the third and final area of this study, we consider the number, location, and sensitivity of the acoustic emission transducers used for proof testing composite pressure vessels.

  3. Volcanic monitoring techniques applied to controlled fragmentation experiments

    NASA Astrophysics Data System (ADS)

    Kueppers, Ulrich; Alatorre-Ibarguengoitia, Miguel; Hort, Matthias; Kremers, Simon; Meier, Kristina; Scharff, Lea; Scheu, Bettina; Taddeucci, Jacopo; Dingwell, Donald B.

    2010-05-01

    A rapidly growing number of people is threatened by natural hazards such as volcanic eruptions, earthquakes, floods, or storms. Volcanic eruptions not only have an impact on their direct neighbourhood but may also affect aviation, infrastructure and climate, regionally as well as globally. In respect to several other natural threats, volcanoes exhibit the advantage of a usually known location of the pending threat, allowing the deployment of sophisticated monitoring networks. Such networks deliver information about volcanic systems and the correct interpretation of monitoring data is a viable key to a successful hazard mitigation strategy. Today a large number of volcanoes is equipped with a variety of scientific instruments that help elucidate the secrets of volcanic phenomena. However, our mechanistic understanding of the processes behind recorded signals or a solid interpretation of the state of a volcano is poor. Experimental volcanology is a chief source of mechanistic understanding of volcanic systems. Here, we bring volcanic monitoring and experimental volcanology together in a campaign of well-monitored, field-based, experimental volcanology. We present results from a multi-parametric combination of well-controlled experiments and several tools commonly used for monitoring active volcanoes. We performed rapid decompression experiments with natural rock samples from Colima volcano (Mexico) to simulate explosive volcanic eruptions. We used 2 sample varieties of approx. 25 and 35 vol.% open porosity. Sample size was 60 mm height and 25 mm and 60 mm diameter, respectively. Applied pressure ranges from 4 to 18 MPa. The pressurised volume above the samples ranges from 60 - 170 cm³. The experiments have been thoroughly monitored with 1) Doppler-Radar, 2) High-speed and video camera, 3) acoustic and infrasonic sensors, 4) pressure transducers, and 5) electrically conducting wires to shed light on fragmentation, ejection, and ejection speed of volcanic pyroclasts

  4. In-situ monitoring of acoustic linear and nonlinear behavior of titanium alloys during cycling loading

    NASA Astrophysics Data System (ADS)

    Frouin, Jerome; Matikas, Theodore E.; Na, Jeong K.; Sathish, Shamachary

    1999-02-01

    An in-situ technique to measure sound velocity, ultrasonic attenuation and acoustic nonlinear property has been developed for characterization and early detection of fatigue damage in aerospace materials. A previous experiment using the f-2f technique on Ti-6Al-4V dog bone specimen fatigued at different stage of fatigue has shown that the material nonlinearity exhibit large change compared to the other ultrasonic parameter. Real-time monitoring of the nonlinearity may be a future tool to characterize early fatigue damage in the material. For this purpose we have developed a computer software and measurement technique including hardware for the automation of the measurement. New transducer holder and special grips are designed. The automation has allowed us to test the long-term stability of the electronics over a period of time and so proof of the linearity of the system. For the first time, a real-time experiment has been performed on a dog-bone specimen from zero fatigue al the way to the final fracture.

  5. Acoustic levitation as an IR spectroscopy sampling technique

    SciTech Connect

    Cronin, J. T.; Brill, T. B.

    1989-02-01

    Acoustic levitation of liquid droplets (/lt/4 mm diameter), bubbles,and solid particles is described as an unusual sampling techniquefor obtaining the infrared spectrum of samples that might be incompatiblewith conventional sample support methods, and for studies of materialsunder extreme conditions. Excellent FT-IR spectra were recorded ofbubbles of a concentrated aqueous nitrate solution, of mineral oil,and of an aqueous surfactant solution. Polymethacrylic acidpacking foam also produced a high-quality spectrum. Large aqueousdroplets and dense solids gave unsatisfactory spectra. The designof the levitator and various spectroscopic considerations are discussed.

  6. Between-hole acoustic surveying and monitoring of a granitic rock mass

    SciTech Connect

    Paulsson, B.N.P.; King, M.S.

    1980-02-01

    The purpose of this technical note is to present preliminary results of an acoustic monitoring study performed as part of a comprehensive rock mechanic and geophysics research program (Ref.20) associated with large-scale heater tests in an abandoned iron-ore mine in central Sweden. The investigation was performed in a fractured granitic rock mass at a sub-surface depth of 340 m, in a drift adjacent to the original iron-ore mine workings. Acoustic monitoring took place between four empty, dry, vertical boreholes of 10 m depth spaced in the vicinity of a vertical heater borehole in the floor of a drift.

  7. Refinement and application of acoustic impulse technique to study nozzle transmission characteristics

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    An improved acoustic impulse technique was developed and was used to study the transmission characteristics of duct/nozzle systems. To accomplish the above objective, various problems associated with the existing spark-discharge impulse technique were first studied. These included (1) the nonlinear behavior of high intensity pulses, (2) the contamination of the signal with flow noise, (3) low signal-to-noise ratio at high exhaust velocities, and (4) the inability to control or shape the signal generated by the source, specially when multiple spark points were used as the source. The first step to resolve these problems was the replacement of the spark-discharge source with electroacoustic driver(s). These included (1) synthesizing on acoustic impulse with acoustic driver(s) to control and shape the output signal, (2) time domain signal averaging to remove flow noise from the contaminated signal, (3) signal editing to remove unwanted portions of the time history, (4) spectral averaging, and (5) numerical smoothing. The acoustic power measurement technique was improved by taking multiple induct measurements and by a modal decomposition process to account for the contribution of higher order modes in the power computation. The improved acoustic impulse technique was then validated by comparing the results derived by an impedance tube method. The mechanism of acoustic power loss, that occurs when sound is transmitted through nozzle terminations, was investigated. Finally, the refined impulse technique was applied to obtain more accurate results for the acoustic transmission characteristics of a conical nozzle and a multi-lobe multi-tube supressor nozzle.

  8. Investigation of pulmonary acoustic simulation: comparing airway model generation techniques

    NASA Astrophysics Data System (ADS)

    Henry, Brian; Dai, Zoujun; Peng, Ying; Mansy, Hansen A.; Sandler, Richard H.; Royston, Thomas

    2014-03-01

    Alterations in the structure and function of the pulmonary system that occur in disease or injury often give rise to measurable spectral, spatial and/or temporal changes in lung sound production and transmission. These changes, if properly quantified, might provide additional information about the etiology, severity and location of trauma, injury, or pathology. With this in mind, the authors are developing a comprehensive computer simulation model of pulmonary acoustics, known as The Audible Human Project™. Its purpose is to improve our understanding of pulmonary acoustics and to aid in interpreting measurements of sound and vibration in the lungs generated by airway insonification, natural breath sounds, and external stimuli on the chest surface, such as that used in elastography. As a part of this development process, finite element (FE) models were constructed of an excised pig lung that also underwent experimental studies. Within these models, the complex airway structure was created via two methods: x-ray CT image segmentation and through an algorithmic means called Constrained Constructive Optimization (CCO). CCO was implemented to expedite the segmentation process, as airway segments can be grown digitally. These two approaches were used in FE simulations of the surface motion on the lung as a result of sound input into the trachea. Simulation results were compared to experimental measurements. By testing how close these models are to experimental measurements, we are evaluating whether CCO can be used as a means to efficiently construct physiologically relevant airway trees.

  9. Common humpback whale (Megaptera novaeangliae) sound types for passive acoustic monitoring.

    PubMed

    Stimpert, Alison K; Au, Whitlow W L; Parks, Susan E; Hurst, Thomas; Wiley, David N

    2011-01-01

    Humpback whales (Megaptera novaeangliae) are one of several baleen whale species in the Northwest Atlantic that coexist with vessel traffic and anthropogenic noise. Passive acoustic monitoring strategies can be used in conservation management, but the first step toward understanding the acoustic behavior of a species is a good description of its acoustic repertoire. Digital acoustic tags (DTAGs) were placed on humpback whales in the Stellwagen Bank National Marine Sanctuary to record and describe the non-song sounds being produced in conjunction with foraging activities. Peak frequencies of sounds were generally less than 1 kHz, but ranged as high as 6 kHz, and sounds were generally less than 1 s in duration. Cluster analysis distilled the dataset into eight groups of sounds with similar acoustic properties. The two most stereotyped and distinctive types ("wops" and "grunts") were also identified aurally as candidates for use in passive acoustic monitoring. This identification of two of the most common sound types will be useful for moving forward conservation efforts on this Northwest Atlantic feeding ground.

  10. The acoustic cough monitoring and manometric profile of cough and throat clearing.

    PubMed

    Xiao, Y; Carson, D; Boris, L; Mabary, J; Lin, Z; Nicodème, F; Cuttica, M; Kahrilas, P J; Pandolfino, J E

    2014-01-01

    Cough and throat clearing might be difficult to differentiate when trying to detect them acoustically or manometrically. The aim of this study was to assess the accuracy of acoustic monitoring for detecting cough and throat clearing, and to also determine whether these two symptoms present with different manometric profiles on esophageal pressure topography. Ten asymptomatic volunteers (seven females, mean age 31.1) were trained to simulate cough and throat clearing in a randomized order every 6 minutes during simultaneous acoustic monitoring and high-resolution manometry. The accuracy of automated acoustic analysis and two blinded reviewers were compared. The pattern of the events and the duration of the pressure changes were assessed using the 30 mmHg isobaric contour. There were 50 cough and 50 throat-clearing events according to the protocol. The sensitivity and specificity of automated acoustic analysis was 84% and 50% for cough, while the blinded analysis using sound revealed a sensitivity and specificity of 94% and 92%. The manometric profile of both cough and throat clearing was similar in terms of qualitative findings; however, cough was associated with a greater number of repetitive pressurizations and a more vigorous upper esophageal sphincter contraction compared with throat clearing. The acoustic analysis software has a moderate sensitivity and poor specificity to detect cough. The profile of cough and throat clearing in pressure topography revealed a similar qualitative pattern of pressurization with more vigorous pressure changes and a greater rate of repetitive pressurizations in cough.

  11. Artificial intelligence techniques for monitoring dangerous infections.

    PubMed

    Lamma, Evelina; Mello, Paola; Nanetti, Anna; Riguzzi, Fabrizio; Storari, Sergio; Valastro, Gianfranco

    2006-01-01

    The monitoring and detection of nosocomial infections is a very important problem arising in hospitals. A hospital-acquired or nosocomial infection is a disease that develops after admission into the hospital and it is the consequence of a treatment, not necessarily a surgical one, performed by the medical staff. Nosocomial infections are dangerous because they are caused by bacteria which have dangerous (critical) resistance to antibiotics. This problem is very serious all over the world. In Italy, almost 5-8% of the patients admitted into hospitals develop this kind of infection. In order to reduce this figure, policies for controlling infections should be adopted by medical practitioners. In order to support them in this complex task, we have developed a system, called MERCURIO, capable of managing different aspects of the problem. The objectives of this system are the validation of microbiological data and the creation of a real time epidemiological information system. The system is useful for laboratory physicians, because it supports them in the execution of the microbiological analyses; for clinicians, because it supports them in the definition of the prophylaxis, of the most suitable antibi-otic therapy and in monitoring patients' infections; and for epidemiologists, because it allows them to identify outbreaks and to study infection dynamics. In order to achieve these objectives, we have adopted expert system and data mining techniques. We have also integrated a statistical module that monitors the diffusion of nosocomial infections over time in the hospital, and that strictly interacts with the knowledge based module. Data mining techniques have been used for improving the system knowledge base. The knowledge discovery process is not antithetic, but complementary to the one based on manual knowledge elicitation. In order to verify the reliability of the tasks performed by MERCURIO and the usefulness of the knowledge discovery approach, we performed a test

  12. Comparison of PAM Systems for Acoustic Monitoring and Further Risk Mitigation Application.

    PubMed

    Ludwig, Stefan; Kreimeyer, Roman; Knoll, Michaela

    2016-01-01

    We present results of the SIRENA 2011 research cruises conducted by the NATO Undersea Research Centre (NURC) and joined by the Research Department for Underwater Acoustics and Geophysics (FWG), Bundeswehr Technical Centre (WTD 71) and the Universities of Kiel and Pavia. The cruises were carried out in the Ligurian Sea. The main aim of the FWG was to test and evaluate the newly developed towed hydrophone array as a passive acoustic monitoring (PAM) tool for risk mitigation applications. The system was compared with the PAM equipment used by the other participating institutions. Recorded sounds were used to improve an automatic acoustic classifier for marine mammals, and validated acoustic detections by observers were compared with the results of the classifier.

  13. Comparison of PAM Systems for Acoustic Monitoring and Further Risk Mitigation Application.

    PubMed

    Ludwig, Stefan; Kreimeyer, Roman; Knoll, Michaela

    2016-01-01

    We present results of the SIRENA 2011 research cruises conducted by the NATO Undersea Research Centre (NURC) and joined by the Research Department for Underwater Acoustics and Geophysics (FWG), Bundeswehr Technical Centre (WTD 71) and the Universities of Kiel and Pavia. The cruises were carried out in the Ligurian Sea. The main aim of the FWG was to test and evaluate the newly developed towed hydrophone array as a passive acoustic monitoring (PAM) tool for risk mitigation applications. The system was compared with the PAM equipment used by the other participating institutions. Recorded sounds were used to improve an automatic acoustic classifier for marine mammals, and validated acoustic detections by observers were compared with the results of the classifier. PMID:26611016

  14. Acoustic Emission Measurement with Fiber Bragg Gratings for Structure Health Monitoring

    NASA Technical Reports Server (NTRS)

    Banks, Curtis E.; Walker, James L.; Russell, Sam; Roth, Don; Mabry, Nehemiah; Wilson, Melissa

    2010-01-01

    Structural Health monitoring (SHM) is a way of detecting and assessing damage to large scale structures. Sensors used in SHM for aerospace structures provide real time data on new and propagating damage. One type of sensor that is typically used is an acoustic emission (AE) sensor that detects the acoustic emissions given off from a material cracking or breaking. The use of fiber Bragg grating (FBG) sensors to provide acoustic emission data for damage detection is studied. In this research, FBG sensors are used to detect acoustic emissions of a material during a tensile test. FBG sensors were placed as a strain sensor (oriented parallel to applied force) and as an AE sensor (oriented perpendicular to applied force). A traditional AE transducer was used to collect AE data to compare with the FBG data. Preliminary results show that AE with FBGs can be a viable alternative to traditional AE sensors.

  15. Monitoring and Analysis of In-Pile Phenomena in Advanced Test Reactor using Acoustic Telemetry

    SciTech Connect

    Agarwal, Vivek; Smith, James A.; Jewell, James Keith

    2015-02-01

    The interior of a nuclear reactor presents a particularly harsh and challenging environment for both sensors and telemetry due to high temperatures and high fluxes of energetic and ionizing particles among the radioactive decay products. A number of research programs are developing acoustic-based sensing approach to take advantage of the acoustic transmission properties of reactor cores. Idaho National Laboratory has installed vibroacoustic receivers on and around the Advanced Test Reactor (ATR) containment vessel to take advantage of acoustically telemetered sensors such as thermoacoustic (TAC) transducers. The installation represents the first step in developing an acoustic telemetry infrastructure. This paper presents the theory of TAC, application of installed vibroacoustic receivers in monitoring the in-pile phenomena inside the ATR, and preliminary data processing results.

  16. Ambient Noise Surface Wave Tomography for Geotechnical Monitoring Using "Large N" Distributed Acoustic Sensing

    NASA Astrophysics Data System (ADS)

    Ajo Franklin, J. B.; Lindsey, N.; Martin, E. R.; Wagner, A. M.; Robertson, M.; Bjella, K.; Gelvin, A.; Ulrich, C.; Wu, Y.; Freifeld, B. M.; Daley, T. M.; Dou, S.

    2015-12-01

    Surface wave tomography using ambient noise sources has found broad application at the regional scale but has not been adopted fully for geotechnical applications despite the abundance of noise sources in this context. The recent development of Distributed Acoustic Sensing (DAS) provides a clear path for inexpensively recording high spatial resolution (< 1m sampling) surface wave data in the context of infrastructure monitoring over significant spatial domains (10s of km). Infrastructure monitoring is particularly crucial in the context of high-latitude installations where a changing global climate can trigger reductions in soil strength due to permafrost thaw. DAS surface wave monitoring systems, particularly those installed in/near transport corridors and coupled to ambient noise inversion algorithms, could be a critical "early warning" system to detect zones of decreased shear strength before failure. We present preliminary ambient noise tomography results from a 1.3 km continuously recording subsurface DAS array used to record traffic noise next to an active road in Fairbanks, AK. The array, depolyed at the Farmer's Loop Permafrost Test Station, was designed as a narrow 2D array and installed via trenching at ~30 cm. We develop a pre-processing and QC approach to analyze the large resulting volume of data, equivalent to a 1300 geophone array sampled at 1 khz. We utilize automated dispersion analysis and a quasi-2D MC inversion to generate a shear wave velocity profile underneath the road in a region of discontinuous permafrost. The results are validated against a high-resolution ERT survey as well as direct-push data on ice content. We also compare vintages of ambient noise DAS data to evaluate the short-term repeatability of the technique in the face of changing noise environments. The resulting dataset demonstrates the utility of using DAS for real-time shear-modulus monitoring in support of critical infrastructure.

  17. Acoustic emission monitoring from a lab scale high shear granulator--a novel approach.

    PubMed

    Watson, N J; Povey, M J W; Reynolds, G K; Xu, B H; Ding, Y

    2014-04-25

    A new approach to the monitoring of granulation processes using passive acoustics together with precise control over the granulation process has highlighted the importance of particle-particle and particle-bowl collisions in acoustic emission. The results have shown that repeatable acoustic results could be obtained but only when a spray nozzle water addition system was used. Acoustic emissions were recorded from a transducer attached to the bowl and an airborne transducer. It was found that the airborne transducer detected very little from the granulation and only experienced small changes throughout the process. The results from the bowl transducer showed that during granulation the frequency content of the acoustic emission shifted towards the lower frequencies. Results from the discrete element model indicate that when larger particles are used the number of collisions the particles experience reduces. This is a result of the volume conservation methodology used in this study, therefore larger particles results in less particles. These simulation results coupled with previous theoretical work on the frequency content of an impacting sphere explain why the frequency content of the acoustic emissions reduces during granule growth. The acoustic system used was also clearly able to identify when large over-wetted granules were present in the system, highlighting its benefit for detecting undesirable operational conditions. High-speed photography was used to study if visual changes in the granule properties could be linked with the changing acoustic emissions. The high speed photography was only possible towards the latter stages of the granulation process and it was found that larger granules produced a higher magnitude of acoustic emission across a broader frequency range.

  18. Acoustic emission monitoring from a lab scale high shear granulator--a novel approach.

    PubMed

    Watson, N J; Povey, M J W; Reynolds, G K; Xu, B H; Ding, Y

    2014-04-25

    A new approach to the monitoring of granulation processes using passive acoustics together with precise control over the granulation process has highlighted the importance of particle-particle and particle-bowl collisions in acoustic emission. The results have shown that repeatable acoustic results could be obtained but only when a spray nozzle water addition system was used. Acoustic emissions were recorded from a transducer attached to the bowl and an airborne transducer. It was found that the airborne transducer detected very little from the granulation and only experienced small changes throughout the process. The results from the bowl transducer showed that during granulation the frequency content of the acoustic emission shifted towards the lower frequencies. Results from the discrete element model indicate that when larger particles are used the number of collisions the particles experience reduces. This is a result of the volume conservation methodology used in this study, therefore larger particles results in less particles. These simulation results coupled with previous theoretical work on the frequency content of an impacting sphere explain why the frequency content of the acoustic emissions reduces during granule growth. The acoustic system used was also clearly able to identify when large over-wetted granules were present in the system, highlighting its benefit for detecting undesirable operational conditions. High-speed photography was used to study if visual changes in the granule properties could be linked with the changing acoustic emissions. The high speed photography was only possible towards the latter stages of the granulation process and it was found that larger granules produced a higher magnitude of acoustic emission across a broader frequency range. PMID:24491527

  19. Identification of the fragmentation of brittle particles during compaction process by the acoustic emission technique.

    PubMed

    Favretto-Cristini, Nathalie; Hégron, Lise; Sornay, Philippe

    2016-04-01

    Some nuclear fuels are currently manufactured by a powder metallurgy process that consists of three main steps, namely preparation of the powders, powder compaction, and sintering of the compact. An optimum between size, shape and cohesion of the particles of the nuclear fuels must be sought in order to obtain a compact with a sufficient mechanical strength, and to facilitate the release of helium and fission gases during irradiation through pores connected to the outside of the pellet after sintering. Being simple to adapt to nuclear-oriented purposes, the Acoustic Emission (AE) technique is used to control the microstructure of the compact by monitoring the compaction of brittle Uranium Dioxide (UO2) particles of a few hundred micrometers. The objective is to identify in situ the mechanisms that occur during the UO2 compaction, and more specifically the particle fragmentation that is linked to the open porosity of the nuclear matter. Three zones of acoustic activity, strongly related to the applied stress, can be clearly defined from analysis of the continuous signals recorded during the compaction process. They correspond to particle rearrangement and/or fragmentation. The end of the noteworthy fragmentation process is clearly defined as the end of the significant process that increases the compactness of the material. Despite the fact that the wave propagation strongly evolves during the compaction process, the acoustic signature of the fragmentation of a single UO2 particle and a bed of UO2 particles under compaction is well identified. The waveform, with a short rise time and an exponential-like decay of the signal envelope, is the most reliable descriptor. The impact of the particle size and cohesion on the AE activity, and then on the fragmentation domain, is analyzed through the discrete AE signals. The maximum amplitude of the burst signals, as well as the mean stress corresponding to the end of the recorded AE, increase with increasing mean diameter of

  20. Acoustic emission monitoring of cement-based structures immobilising radioactive waste

    SciTech Connect

    Spasova, L.M.; Ojovan, M.I.; Hayes, M.; Godfrey, H.

    2007-07-01

    The long term performance of cementitious structures immobilising radioactive waste can be affected by physical and chemical processes within the encapsulating materials such as formation of new phases (e.g., vaterite, brucite), degradation of cement phases (e.g., CSH gel, portlandite), degradation of some waste components (e.g., organics), corrosion of metallic constituents (aluminium, magnesium), gas emission, further hydration etc. The corrosion of metals in the high pH cementitious environment is of especial concern as it can potentially cause wasteform cracking. One of the perspective non-destructive methods used to monitor and assess the mechanical properties of materials and structures is based on an acoustic emission (AE) technique. In this study an AE non-destructive technique was used to evaluate the mechanical performance of cementitious structures with encapsulated metallic waste such as aluminium. AE signals generated as a result of aluminium corrosion in a small-size blast furnace slag (BFS)/ordinary Portland cement (OPC) sample were detected, recorded and analysed. A procedure for AE data analysis including conventional parameter-based AE approach and signal-based analysis was applied and demonstrated to provide information on the aluminium corrosion process and its impact on the mechanical performance of the encapsulating cement matrix. (authors)

  1. Remote Sensing Techniques for Monitoring Aquatic Vegetation

    NASA Astrophysics Data System (ADS)

    Blanco, Alfonso

    Hydrilla is an important submerged aquatic vegetation because it has a large capacity to absorb pollutants and it is an indicator of the eutrophic status of a waterbody. Monitoring and restoration of submerged aquatic vegetation is key for the preservation and restoration of the Chesapeake Bay. Remote sensing techniques have been used for assessing wetlands and non-invasive aquatic species, but there is limited studies of hydrilla monitoring combined with space-borne, airborne and in-situ remote sensing measurements for detecting and mapping hydrilla infestation. The first objective of this research was to establish a database of hydrilla spectral signatures from an experimental tank and from a field setting using a handheld spectrometer. The spectral signatures collected will be used to identify the optimal spectral and spatial characteristics that are required to identify and classify the distribution of hydrilla canopies in water bodies. The second objective is to process and analyze two hyperspectral images from a space-borne (Hyperion) and airborne (AISA) sensors with ENVI for detecting and mapping the infestation of hydrilla vertillicata in a coastal estuary in Chesapeake Bay. The third objective was to validate the satellite and airborne hyperspectral images with the spectral signatures collected with the in-situ field measurements. In addition, the Hyperion and AISA imaging results were compared with ground surveys and aerial photos collected by the Maryland Department of Natural Resources and the Virginia Institute of Marine Sciences for verifying the extent and the location of the hydrilla canopies. The hyperspectral analysis of both sensors provided for a dual results, one is the identification and classification of hydrilla from hyperspectral imaging sensors and secondly the identification of algae blooms in very productive waters. A hydrilla spectral signature database was established and housed in GMU's EastFIRE Lab of Environmental Science and

  2. Advanced Computing Methods for Knowledge Discovery and Prognosis in Acoustic Emission Monitoring

    ERIC Educational Resources Information Center

    Mejia, Felipe

    2012-01-01

    Structural health monitoring (SHM) has gained significant popularity in the last decade. This growing interest, coupled with new sensing technologies, has resulted in an overwhelming amount of data in need of management and useful interpretation. Acoustic emission (AE) testing has been particularly fraught by the problem of growing data and is…

  3. Acoustic Emission Monitoring of the DC-XA Composite Liquid Hydrogen Tank During Structural Testing

    NASA Technical Reports Server (NTRS)

    Wilkerson, C.

    1996-01-01

    The results of acoustic emission (AE) monitoring of the DC-XA composite liquid hydrogen tank are presented in this report. The tank was subjected to pressurization, tensile, and compressive loads at ambient temperatures and also while full of liquid nitrogen. The tank was also pressurized with liquid hydrogen. AE was used to monitor the tank for signs of structural defects developing during the test.

  4. Application of finite element techniques in predicting the acoustic properties of turbofan inlets

    NASA Technical Reports Server (NTRS)

    Majjigi, R. K.; Sigman, R. K.; Zinn, B. T.

    1978-01-01

    An analytical technique was developed for predicting the acoustic performance of turbofan inlets carrying a subsonic axisymmetric steady flow. The finite element method combined with the method of weighted residuals is used in predicting the acoustic properties of variable area, annular ducts with or without acoustic treatments along their walls. An approximate solution for the steady inviscid flow field is obtained using an integral method for calculating the incompressible potential flow field in the inlet with a correction to account for compressibility effects. The accuracy of the finite element technique was assessed by comparison with available analytical solutions for the problems of plane and spinning wave propagation through a hard walled annular cylinder with a constant mean flow.

  5. Acoustic Emission and Guided Wave Monitoring of Fatigue Crack Growth on a Full Pipe Specimen

    SciTech Connect

    Meyer, Ryan M.; Cumblidge, Stephen E.; Ramuhalli, Pradeep; Watson, Bruce E.; Doctor, Steven R.; Bond, Leonard J.

    2011-05-06

    Continuous on-line monitoring of active and passive systems, structures and components in nuclear power plants will be critical to extending the lifetimes of nuclear power plants in the US beyond 60 years. Acoustic emission and guided ultrasonic waves are two tools for continuously monitoring passive systems, structures and components within nuclear power plants and are the focus of this study. These tools are used to monitor fatigue damage induced in a SA 312 TP304 stainless steel pipe specimen. The results of acoustic emission monitoring indicate that crack propagation signals were not directly detected. However, acoustic emission monitoring exposed crack formation prior to visual confirmation through the detection of signals caused by crack closure friction. The results of guided ultrasonic wave monitoring indicate that this technology is sensitive to the presence and size of cracks. The sensitivity and complexity of GUW signals is observed to vary with respect to signal frequency and path traveled by the guided ultrasonic wave relative to the crack orientation.

  6. The application of compressed sensing to long-term acoustic emission-based structural health monitoring

    NASA Astrophysics Data System (ADS)

    Cattaneo, Alessandro; Park, Gyuhae; Farrar, Charles; Mascareñas, David

    2012-04-01

    The acoustic emission (AE) phenomena generated by a rapid release in the internal stress of a material represent a promising technique for structural health monitoring (SHM) applications. AE events typically result in a discrete number of short-time, transient signals. The challenge associated with capturing these events using classical techniques is that very high sampling rates must be used over extended periods of time. The result is that a very large amount of data is collected to capture a phenomenon that rarely occurs. Furthermore, the high energy consumption associated with the required high sampling rates makes the implementation of high-endurance, low-power, embedded AE sensor nodes difficult to achieve. The relatively rare occurrence of AE events over long time scales implies that these measurements are inherently sparse in the spike domain. The sparse nature of AE measurements makes them an attractive candidate for the application of compressed sampling techniques. Collecting compressed measurements of sparse AE signals will relax the requirements on the sampling rate and memory demands. The focus of this work is to investigate the suitability of compressed sensing techniques for AE-based SHM. The work explores estimating AE signal statistics in the compressed domain for low-power classification applications. In the event compressed classification finds an event of interest, ι1 norm minimization will be used to reconstruct the measurement for further analysis. The impact of structured noise on compressive measurements is specifically addressed. The suitability of a particular algorithm, called Justice Pursuit, to increase robustness to a small amount of arbitrary measurement corruption is investigated.

  7. Deep diving odontocetes foraging strategies and their prey field as determined by acoustic techniques

    NASA Astrophysics Data System (ADS)

    Giorli, Giacomo

    Deep diving odontocetes, like sperm whales, beaked whales, Risso's dolphins, and pilot whales are known to forage at deep depths in the ocean on squid and fish. These marine mammal species are top predators and for this reason are very important for the ecosystems they live in, since they can affect prey populations and control food web dynamics through top-down effects. The studies presented in this thesis investigate deep diving odontocetes. foraging strategies, and the density and size of their potential prey in the deep ocean using passive and active acoustic techniques. Ecological Acoustic Recorders (EAR) were used to monitor the foraging activity of deep diving odontocetes at three locations around the world: the Josephine Seamount High Sea Marine Protected Area (JHSMPA), the Ligurian Sea, and along the Kona coast of the island of Hawaii. In the JHSMPA, sperm whales. and beaked whales. foraging rates do not differ between night-time and day-time. However, in the Ligurian Sea, sperm whales switch to night-time foraging as the winter approaches, while beaked whales alternate between hunting mainly at night, and both at night and at day. Spatial differences were found in deep diving odontocetes. foraging activity in Hawaii where they forage most in areas with higher chlorophyll concentrations. Pilot whales (and false killer whales, clustered together in the category "blackfishes") and Risso's dolphins forage mainly at night at all locations. These two species adjust their foraging activity with the length of the night. The density and size of animals living in deep sea scattering layers was studied using a DIDSON imaging sonar at multiple stations along the Kona coast of Hawaii. The density of animals was affected by location, depth, month, and the time of day. The size of animals was influenced by station and month. The DIDSON proved to be a successful, non-invasive technique to study density and size of animals in the deep sea. Densities were found to be an

  8. FEASIBILITY OF ACOUSTIC METHODS FOR IMPURITY GAS MONITORING IN DRY STORAGE SYSTEMS

    SciTech Connect

    Meyer, Ryan M.; Cuta, Judith M.; Jones, Anthony M.; Denslow, Kayte M.; Ramuhalli, Pradeep; Adkins, Harold E.; Hanson, Brady D.

    2015-05-01

    This paper explores the feasibility of monitoring impurities in dry storage containers (DSCs) for spent nuclear fuel using non-invasive acoustic sensing. The conceived implementation considers measurements based on changes in acoustic velocity at successive measurement intervals. Uncertainty contributions from the measurement system and temperature variability are estimated. Sources of temperature variability considered include changes in the decay heat source over time and ambient temperature variation. The results show that performance of a system which does not incorporate temperature compensation will be dependent upon geographic location and the decay heat source strength. The results also indicate that an annual measurement interval is optimal.

  9. Infrasound monitoring, acoustic-gravity waves and global atmospheric dynamics

    NASA Astrophysics Data System (ADS)

    Blanc, E.; Le Pichon, A.; Ceranna, L.; Farges, T.

    2008-12-01

    For the verification of the Comprehensive nuclear Test Ban Treaty, the International Monitoring System has been developed. As part of this system, the infrasound network provides an unique opportunity to monitor continuously pressure waves in the atmosphere. Such infrasonic waves propagate in the channel formed by the temperature and wind gradients of the atmosphere. Long term observations provide information about the evolution of the propagation conditions and then of atmospheric parameters. The monitoring of continuous sources, as ocean swell, gives the characteristics of the stratospheric wave channel submitted to stratospheric warming effects. Large scale gravity waves, which are also observed by the network, produce a forcing of the stratosphere at low and middle latitudes and long-lived changes in the stratospheric circulation towards high latitudes, leading to fluctuations in the strength of the polar vortex. These fluctuations move down to the lower stratosphere with possible effects on the tropospheric temperature. Gravity wave monitoring in Antarctica reveals a gravity wave system probably related to the wind effect over mountains. At mid latitudes an additional main sources of disturbances is the thunderstorm activity. The infrasound monitoring system allows a better knowledge of the atmospheric wave systems and of the dynamics of the atmosphere. In return this better knowledge of the wave systems allow a better identification of the possible explosion signals in the background of the atmospheric waves and then to improve the discrimination methods

  10. Multiscale monitoring of interface failure of brittle coating/ductile substrate systems: A non-destructive evaluation method combined digital image correlation with acoustic emission

    NASA Astrophysics Data System (ADS)

    Mao, W. G.; Wu, D. J.; Yao, W. B.; Zhou, M.; Lu, C.

    2011-10-01

    In this paper, we proposed a non-destructive evaluation method combined digital image correlation with acoustic emission techniques. The method was used to in situ monitor interface failure and internal damage of brittle coating/ductile substrate systems with different size scales. The results show that there is a good relationship between digital image correlation and acoustic emission signals, which can be applied to judge cracking formation and coating delamination and to determine fracture toughness of a thermal barrier coating system subjected to bending.

  11. Acoustic emission of offshore structures, attenuation - noise - crack monitoring

    SciTech Connect

    Lovaas, S.

    1985-01-01

    No NDT crack detection methods have up to now proved to be the method which can overrule the others. We shall probably in the future in the offshore industry see a combination of various structure monitoring systems, remotely operated vehicles (ROV) with NDT-equipment and also the use of divers. The author believes that in some 5 - 10 years ROVs will perform much of the routine inspection, and mobile monitoring instrumentation will be concentrated to some hot spot areas, already detected defects or any repairs. The main areas for AE are monitoring of pressure vessels and fibre reinforced plastics. For application on offshore structures some fullscale trials have been performed (with practical problems) as well as some laboratory studies. Norwegian institutions seem to have a leading role today in the research of offshore applications. Norsk Hydro participated in a signature analysis project at Sintef/Veritas some years ago.

  12. Acoustic Emission Monitoring of Multicell Reinforced Concrete Box Girders Subjected to Torsion

    PubMed Central

    Bagherifaez, Marya; Behnia, Arash; Majeed, Abeer Aqeel; Hwa Kian, Chai

    2014-01-01

    Reinforced concrete (RC) box girders are a common structural member for road bridges in modern construction. The hollow cross-section of a box girder is ideal in carrying eccentric loads or torques introduced by skew supports. This study employed acoustic emission (AE) monitoring on multicell RC box girder specimens subjected to laboratory-based torsion loading. Three multicell box girder specimens with different cross-sections were tested. The aim is to acquire AE analysis data indicative for characterizing torsion fracture in the box girders. It was demonstrated through appropriate parametric analysis that the AE technique could be utilized to effectively classify fracture developed in the specimens for describing their mechanical behavior under torsion. AE events localization was presented to illustrate the trend of crack and damage propagation in different stages of fracture. It could be observed that spiral-like patterns of crack were captured through AE damage localization system and damage was quantified successfully in different stages of fracture by using smoothed b-value analysis. PMID:25180203

  13. Acoustic emission monitoring of multicell reinforced concrete box girders subjected to torsion.

    PubMed

    Bagherifaez, Marya; Behnia, Arash; Majeed, Abeer Aqeel; Hwa Kian, Chai

    2014-01-01

    Reinforced concrete (RC) box girders are a common structural member for road bridges in modern construction. The hollow cross-section of a box girder is ideal in carrying eccentric loads or torques introduced by skew supports. This study employed acoustic emission (AE) monitoring on multicell RC box girder specimens subjected to laboratory-based torsion loading. Three multicell box girder specimens with different cross-sections were tested. The aim is to acquire AE analysis data indicative for characterizing torsion fracture in the box girders. It was demonstrated through appropriate parametric analysis that the AE technique could be utilized to effectively classify fracture developed in the specimens for describing their mechanical behavior under torsion. AE events localization was presented to illustrate the trend of crack and damage propagation in different stages of fracture. It could be observed that spiral-like patterns of crack were captured through AE damage localization system and damage was quantified successfully in different stages of fracture by using smoothed b-value analysis. PMID:25180203

  14. Acoustic emission monitoring of low velocity impact damage in graphite/epoxy laminates during tensile loading

    NASA Technical Reports Server (NTRS)

    Parker, Bradford H.

    1992-01-01

    An acoustic emission (AE) system was set up in a linear location data acquisition mode to monitor the tensile loading of eight-ply quasi-isotropic graphite/epoxy specimens containing low velocity impact damage. The impact damage was induced using an instrumented drop weight tower. During impact, specimens were supported by either an aluminum plate or a membrane configuration. Cross-sectional examinations revealed that the aluminum plate configuration resulted in primarily matrix cracking and back surface fiber failure. The membrane support resulted in only matrix cracking and delamination damage. Penetrant enhanced radiography and immersion ultrasonics were used in order to assess the amount of impact damage in each tensile specimen. During tensile loading, AE reliably detected and located the damage sites which included fiber failure. All specimens with areas of fiber breakage ultimately failed at the impact site. AE did not reliably locate damage which consisted of only delaminations and matrix cracking. Specimens with this type of damage did not ultimately fail at the impact site. In summary, AE demonstrated the ability to increase the reliability of structural proof tests; however, the successful use of this technique requires extensive baseline testing.

  15. A Catheter-Based Acoustic Interrogation Device for Monitoring Motility Dynamics of the Lower Esophageal Sphincter

    PubMed Central

    Lu, Qian; Yadid-Pecht, Orly; Sadowski, Daniel C.; Mintchev, Martin P.

    2014-01-01

    This paper presents novel minimally-invasive, catheter-based acoustic interrogation device for monitoring motility dynamics of the lower esophageal sphincter (LES). A micro-oscillator actively emitting sound wave at 16 kHz is located at one side of the LES, and a miniature microphone is located at the other side of the sphincter to capture the sound generated from the oscillator. Thus, the dynamics of the opening and closing of the LES can be quantitatively assessed. In this paper, experiments are conducted utilizing an LES motility dynamics simulator. The sound strength is captured by the microphone and is correlated to the level of LES opening and closing controlled by the simulator. Measurements from the simulator model show statistically significant (p < 0.05) Pearson correlation coefficients (0.905 on the average in quiet environment and 0.736 on the average in noisy environment, D.O.F. = 9). Measuring the level of LES opening and closing has the potential to become a valuable diagnostic technique for understanding LES dysfunction and the disorders associated with it. PMID:25120160

  16. Acoustic angiography: a new high frequency contrast ultrasound technique for biomedical imaging

    NASA Astrophysics Data System (ADS)

    Shelton, Sarah E.; Lindsey, Brooks D.; Gessner, Ryan; Lee, Yueh; Aylward, Stephen; Lee, Hyunggyun; Cherin, Emmanuel; Foster, F. Stuart; Dayton, Paul A.

    2016-05-01

    Acoustic Angiography is a new approach to high-resolution contrast enhanced ultrasound imaging enabled by ultra-broadband transducer designs. The high frequency imaging technique provides signal separation from tissue which does not produce significant harmonics in the same frequency range, as well as high resolution. This approach enables imaging of microvasculature in-vivo with high resolution and signal to noise, producing images that resemble x-ray angiography. Data shows that acoustic angiography can provide important information about the presence of disease based on vascular patterns, and may enable a new paradigm in medical imaging.

  17. Volcanic Monitoring Techniques Applied to Controlled Fragmentation Experiments

    NASA Astrophysics Data System (ADS)

    Kueppers, U.; Alatorre-Ibarguengoitia, M. A.; Hort, M. K.; Kremers, S.; Meier, K.; Scharff, L.; Scheu, B.; Taddeucci, J.; Dingwell, D. B.

    2010-12-01

    Volcanic eruptions are an inevitable natural threat. The range of eruptive styles is large and short term fluctuations of explosivity or vent position pose a large risk that is not necessarily confined to the immediate vicinity of a volcano. Explosive eruptions rather may also affect aviation, infrastructure and climate, regionally as well as globally. Multiparameter monitoring networks are deployed on many active volcanoes to record signs of magmatic processes and help elucidate the secrets of volcanic phenomena. However, our mechanistic understanding of many processes hiding in recorded signals is still poor. As a direct consequence, a solid interpretation of the state of a volcano is still a challenge. In an attempt to bridge this gap, we combined volcanic monitoring and experimental volcanology. We performed 15 well-monitored, field-based, experiments and fragmented natural rock samples from Colima volcano (Mexico) by rapid decompression. We used cylindrical samples of 60 mm height and 25 mm and 60 mm diameter, respectively, and 25 and 35 vol.% open porosity. The applied pressure range was from 4 to 18 MPa. Using different experimental set-ups, the pressurised volume above the samples ranged from 60 - 170 cm3. The experiments were performed at ambient conditions and at controlled sample porosity and size, confinement geometry, and applied pressure. The experiments have been thoroughly monitored with 1) Doppler Radar (DR), 2) high-speed and high-definition cameras, 3) acoustic and infrasound sensors, 4) pressure transducers, and 5) electrically conducting wires. Our aim was to check for common results achieved by the different approaches and, if so, calibrate state-of-the-art monitoring tools. We present how the velocity of the ejected pyroclasts was measured by and evaluated for the different approaches and how it was affected by the experimental conditions and sample characteristics. We show that all deployed instruments successfully measured the pyroclast

  18. Acoustic Emission and Guided Ultrasonic Waves for Detection and Continuous Monitoring of Cracks in Light Water Reactor Components

    SciTech Connect

    Meyer, Ryan M.; Coble, Jamie B.; Ramuhalli, Pradeep; Watson, Bruce E.; Cumblidge, Stephen E.; Doctor, Steven R.; Bond, Leonard J.

    2012-06-28

    Acoustic emission (AE) and guided ultrasonic waves (GUW) are considered for continuous monitoring and detection of cracks in Light Water Reactor (LWR) components. In this effort, both techniques are applied to the detection and monitoring of fatigue crack growth in a full scale pipe component. AE results indicated crack initiation and rapid growth in the pipe, and significant GUW responses were observed in response to the growth of the fatigue crack. After initiation, the crack growth was detectable with AE for approximately 20,000 cycles. Signals associated with initiation and rapid growth where distinguished based on total rate of activity and differences observed in the centroid frequency of hits. An intermediate stage between initiation and rapid growth was associated with significant energy emissions, though few hits. GUW exhibit a nearly monotonic trend with crack length with an exception of measurements obtained at 41 mm and 46 mm.

  19. Volcano deformation--Geodetic monitoring techniques

    USGS Publications Warehouse

    Dzurisin, Daniel; Lu, Zhong

    2007-01-01

    This book describes the techniques used by volcanologists to successfully predict several recent volcanic eruptions by combining information from various scientific disciplines, including geodetic techniques. Many recent developments in the use of state-of-the-art and emerging techniques, including Global Positioning System and Synthetic Aperture Radar Interferometry, mean that most books on volcanology are out of date, and this book includes chapters devoted entirely to these two techniques.

  20. BIOSEPARATION AND BIOANALYTICAL TECHNIQUES IN ENVIRONMENTAL MONITORING

    EPA Science Inventory

    The growing use of antibody-based separation methods has paralleled the expansion of immunochemical detection methods in moving beyond the clinical diagnostic field to applications in environmental monitoring. In recent years high-performance immunoaffinity chromatography, which ...

  1. Numerical and experimental investigation of a low-frequency measurement technique: differential acoustic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Yin, Hanjun; Zhao, Jianguo; Tang, Genyang; Ma, Xiaoyi; Wang, Shangxu

    2016-06-01

    Differential acoustic resonance spectroscopy (DARS) has been developed to determine the elastic properties of saturated rocks within the kHz frequency range. This laboratory technique is based on considerations from perturbation theory, wherein the resonance frequencies of the resonant cavity with and without a perturbation sample are used to estimate the acoustic properties of the test sample. In order to better understand the operating mechanism of DARS and therefore optimize the procedure, it is important to develop an accurate and efficient numerical model. Accordingly, this study presents a new multiphysics model by coupling together considerations from acoustics, solid mechanics, and electrostatics. The numerical results reveal that the newly developed model can successfully simulate the acoustic pressure field at different resonance modes, and that it can accurately reflect the measurement process. Based on the understanding of the DARS system afforded by the numerical simulation, we refine the system configuration by utilizing cavities of different lengths and appropriate radii to broaden the frequency bandwidth and ensure testing accuracy. Four synthetic samples are measured to test the performance of the optimized DARS system, in conjunction with ultrasonic and static measurements. For nonporous samples, the estimated bulk moduli are shown to be independent of the different measurement methods (i.e. DARS or ultrasonic techniques). In contrast, for sealed porous samples, the differences in bulk moduli between the low- and high-frequency techniques can be clearly observed; this discrepancy is attributed to frequency dispersion. In summary, the optimized DARS system with an extended frequency range of 500–2000 Hz demonstrates considerable utility in investigating the frequency dependence of the acoustic properties of reservoir rocks.

  2. Detection of internal cracks in Manchego cheese using the acoustic impulse-response technique and ultrasounds.

    PubMed

    Conde, T; Mulet, A; Clemente, G; Benedito, J

    2008-03-01

    Nowadays, due to the more global nature of markets, the commercialization of cheese relies on the high quality of the product. Internal defects such as cracks or flaws may affect quality. Two different nondestructive inspection techniques (ultrasonic and acoustic experiments) were used to detect cracks in Manchego cheese. The existence of small eyes in this type of cheese limited the use of ultrasonic pulse-echo experiments due to high scattering, and only cracks close to the surface of the cheese could be detected. The acoustic impulse-response technique, however, allowed us to study wheel pieces with cracks located elsewhere in the cheese. Two different impact probes (A and B) were assayed. The energy content of the acoustic spectrum was higher for cracked wheel pieces (7,116 and 17,520 V Hz(1/2) for probes A and B, respectively) than for normal ones (6,841 and 16,821 V Hz(1/2)). The differences were mainly found for frequencies higher than 150 Hz, which made the centroid for cracked pieces higher (162 and 170 Hz for probes A and B, respectively) than that for normal cheeses (132 and 148 Hz for probes A and B, respectively). Discriminant functions were developed to classify wheel pieces, and the input variables used were the acoustic parameters from the spectrum and the principal components extracted from the whole spectrum. The best classification procedure used the principal components from the principal components analysis of the spectrum for probe B. In this case, the 50 wheel pieces used in this study were correctly classified. These results showed that a simple and low-cost acoustic impulse-response technique could be used to detect cheese cracks, formed at different moments of Manchego cheese maturation. PMID:18292247

  3. Numerical and experimental investigation of a low-frequency measurement technique: differential acoustic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Yin, Hanjun; Zhao, Jianguo; Tang, Genyang; Ma, Xiaoyi; Wang, Shangxu

    2016-06-01

    Differential acoustic resonance spectroscopy (DARS) has been developed to determine the elastic properties of saturated rocks within the kHz frequency range. This laboratory technique is based on considerations from perturbation theory, wherein the resonance frequencies of the resonant cavity with and without a perturbation sample are used to estimate the acoustic properties of the test sample. In order to better understand the operating mechanism of DARS and therefore optimize the procedure, it is important to develop an accurate and efficient numerical model. Accordingly, this study presents a new multiphysics model by coupling together considerations from acoustics, solid mechanics, and electrostatics. The numerical results reveal that the newly developed model can successfully simulate the acoustic pressure field at different resonance modes, and that it can accurately reflect the measurement process. Based on the understanding of the DARS system afforded by the numerical simulation, we refine the system configuration by utilizing cavities of different lengths and appropriate radii to broaden the frequency bandwidth and ensure testing accuracy. Four synthetic samples are measured to test the performance of the optimized DARS system, in conjunction with ultrasonic and static measurements. For nonporous samples, the estimated bulk moduli are shown to be independent of the different measurement methods (i.e. DARS or ultrasonic techniques). In contrast, for sealed porous samples, the differences in bulk moduli between the low- and high-frequency techniques can be clearly observed; this discrepancy is attributed to frequency dispersion. In summary, the optimized DARS system with an extended frequency range of 500-2000 Hz demonstrates considerable utility in investigating the frequency dependence of the acoustic properties of reservoir rocks.

  4. Apparatus and method for acoustic monitoring of steam quality and flow

    DOEpatents

    Sinha, Dipen N.; Pantea, Cristian

    2016-09-13

    An apparatus and method for noninvasively monitoring steam quality and flow and in pipes or conduits bearing flowing steam, are described. By measuring the acoustic vibrations generated in steam-carrying conduits by the flowing steam either by direct contact with the pipe or remotely thereto, converting the measured acoustic vibrations into a frequency spectrum characteristic of the natural resonance vibrations of the pipe, and monitoring the amplitude and/or the frequency of one or more chosen resonance frequencies, changes in the steam quality in the pipe are determined. The steam flow rate and the steam quality are inversely related, and changes in the steam flow rate are calculated from changes in the steam quality once suitable calibration curves are obtained.

  5. Wireless surface acoustic wave sensors for displacement and crack monitoring in concrete structures

    NASA Astrophysics Data System (ADS)

    Perry, M.; McKeeman, I.; Saafi, M.; Niewczas, P.

    2016-03-01

    In this work, we demonstrate that wireless surface acoustic wave devices can be used to monitor millimetre displacements in crack opening during the cyclic and static loading of reinforced concrete structures. Sensors were packaged to extend their gauge length and to protect them against brittle fracture, before being surface-mounted onto the tensioned surface of a concrete beam. The accuracy of measurements was verified using computational methods and optical-fibre strain sensors. After packaging, the displacement and temperature resolutions of the surface acoustic wave sensors were 10 μ {{m}} and 2 °C respectively. With some further work, these devices could be retrofitted to existing concrete structures to facilitate wireless structural health monitoring.

  6. Thermometric- and Acoustic-Based Beam Power Monitor for Ultra-Bright X-Rays

    SciTech Connect

    Bentsen, Gregory; /Rochester U. /SLAC

    2010-08-25

    A design for an average beam power monitor for ultra-bright X-ray sources is proposed that makes simultaneous use of calorimetry and radiation acoustics. Radiation incident on a solid target will induce heating and ultrasonic vibrations, both of which may be measured to give a fairly precise value of the beam power. The monitor is intended for measuring ultra-bright Free-Electron Laser (FEL) X-ray beams, for which traditional monitoring technologies such as photo-diodes or scintillators are unsuitable. The monitor consists of a Boron Carbide (B{sub 4}C) target designed to absorb most of the incident beam's energy. Resistance temperature detectors (RTD) and piezoelectric actuators are mounted on the outward faces of the target to measure the temperature changes and ultrasonic vibrations induced by the incident beam. The design was tested using an optical pulsed beam (780 nm, 120 and 360 Hz) from a Ti:sapphire oscillator at several energies between 0.8 and 2.6 mJ. The RTDs measured an increase in temperature of about 10 K over a period of several minutes. The piezoelectric sensors recorded ringing acoustic oscillations at 580 {+-} 40 kHz. Most importantly, the amplitude of the acoustic signals was observed to scale linearly with beam power up to 2 mJ of pulse energy. Above this pulse energy, the vibrational signals became nonlinear. Several causes for this nonlinearity are discussed, including amplifier saturation and piezoelectric saturation. Despite this nonlinearity, these measurements demonstrate the feasibility of such a beam power measurement device. The advantage of two distinct measurements (acoustic and thermometric) provides a useful method of calibration that is unavailable to current LCLS diagnostics tools.

  7. Normalization and source separation of acoustic emission signals for condition monitoring and fault detection of multi-cylinder diesel engines

    NASA Astrophysics Data System (ADS)

    Wu, Weiliang; Lin, Tian Ran; Tan, Andy C. C.

    2015-12-01

    A signal processing technique is presented in this paper to normalize and separate the source of non-linear acoustic emission (AE) signals of a multi-cylinder diesel engine for condition monitoring applications and fault detection. The normalization technique presented in the paper overcomes the long-existing non-linearity problem of AE sensors so that responses measured by different AE sensors can be quantitatively analysed and compared. A source separation algorithm is also developed in the paper to separate the mixture of the normalized AE signals produced by a multi-cylinder diesel engine by utilising the system parameters (i.e., wave attenuation constant and the arrival time delay) of AE wave propagation determined by a standard pencil lead break test on the engine cylinder head. It is shown that the source separation algorithm is able to separate the signal interference of adjacent cylinders from the monitored cylinder once the wave attenuation constant and the arrival time delay along the propagation path are known. The algorithm is particularly useful in the application of AE technique for condition monitoring of small-size diesel engines where signal interference from the neighbouring cylinders is strong.

  8. Validating Ultrasound-based HIFU Lesion-size Monitoring Technique with MR Thermometry and Histology

    NASA Astrophysics Data System (ADS)

    Zhou, Shiwei; Petruzzello, John; Anand, Ajay; Sethuraman, Shriram; Azevedo, Jose

    2010-03-01

    In order to control and monitor HIFU lesions accurately and cost-effectively in real-time, we have developed an ultrasound-based therapy monitoring technique using acoustic radiation force to track the change in tissue mechanical properties. We validate our method with concurrent MR thermometry and histology. Comparison studies have been completed on in-vitro bovine liver samples. A single-element 1.1 MHz focused transducer was used to deliver HIFU and produce acoustic radiation force (ARF). A 5 MHz single-element transducer was placed co-axially with the HIFU transducer to acquire the RF data, and track the tissue displacement induced by ARF. During therapy, the monitoring procedure was interleaved with HIFU. MR thermometry (Philips Panorama 1T system) and ultrasound monitoring were performed simultaneously. The tissue temperature and thermal dose (CEM43 = 240 mins) were computed from the MR thermometry data. The tissue displacement induced by the acoustic radiation force was calculated from the ultrasound RF data in real-time using a cross-correlation based method. A normalized displacement difference (NDD) parameter was developed and calibrated to estimate the lesion size. The lesion size estimated by the NDD was compared with both MR thermometry prediction and the histology analysis. For lesions smaller than 8mm, the NDD-based lesion monitoring technique showed very similar performance as MR thermometry. The standard deviation of lesion size error is 0.66 mm, which is comparable to MR thermal dose contour prediction (0.42 mm). A phased array is needed for tracking displacement in 2D and monitoring lesion larger than 8 mm. The study demonstrates the potential of our ultrasound based technique to achieve precise HIFU lesion control through real-time monitoring. The results compare well with histology and an established technique like MR Thermometry. This approach provides feedback control in real-time to terminate therapy when a pre-determined lesion size is

  9. An Aquatic Acoustic Metrics Interface Utility for Underwater Sound Monitoring and Analysis

    SciTech Connect

    Ren, Huiying; Halvorsen, Michele B.; Deng, Zhiqun; Carlson, Thomas J.

    2012-05-31

    Fishes and other marine mammals suffer a range of potential effects from intense sound sources generated by anthropogenic underwater processes such as pile driving, shipping, sonars, and underwater blasting. Several underwater sound recording devices (USR) were built to monitor the acoustic sound pressure waves generated by those anthropogenic underwater activities, so the relevant processing software becomes indispensable for analyzing the audio files recorded by these USRs. However, existing software packages did not meet performance and flexibility requirements. In this paper, we provide a detailed description of a new software package, named Aquatic Acoustic Metrics Interface (AAMI), which is a Graphical User Interface (GUI) designed for underwater sound monitoring and analysis. In addition to the general functions, such as loading and editing audio files recorded by USRs, the software can compute a series of acoustic metrics in physical units, monitor the sound's influence on fish hearing according to audiograms from different species of fishes and marine mammals, and batch process the sound files. The detailed applications of the software AAMI will be discussed along with several test case scenarios to illustrate its functionality.

  10. Monitoring the Lateral Gradient of Sound Speed in Ocean Toward Fast GPS/Acoustic Seafloor Positioning for the Cabled System

    NASA Astrophysics Data System (ADS)

    Kido, M.; Osada, Y.; Fujimoto, H.; Kaneda, Y.

    2007-12-01

    The GPS/acoustic technique is now in practical use for seafloor positioning to monitor crustal deformation beneath the ocean, where land-based GPS networks are not available. To achieve semi-realtime monitoring of the strain accumulation and possible precursor for the expected Nankai earthquake in Japan, JAMSTEC and others have started so called DONET project (Development of Dense Ocean-floor Network System for Earthquakes and Tsunamis), funded by MEXT Japan, where numerous seismometers, pressure gauges, and acoustic ranging instruments are going to be equipped through the planing seafloor cables at Kumano-nada. A GPS/acoustic system will be combined in part of the cable system. The present GPS/acoustic survey, which acoustically measures slant ranges between a surface transducer and three seafloor transponders, has a fault to get position in semi-realtime. The problem setting supposes a laterally stratified sound speed structure. Violation of this condition with lateral gradient in sound speed results in the deviation of apparent position of the transponders. At present, ~5~cm of accuracy is achieved after taking time-average more than 1~day to cancel-out the time-varying direction of the gradient. In addition, if a long-lived gradient appeared, we have no way to distinguish seafloor displacement from the gradient. To overcome the present status, we propose a new survey style which actively estimates the sound speed gradient and makes its correction on apparent positioning by using five transponders. This rather complicated survey style requires severe layout of the transponders and observing position to stably resolve five unknowns: the horizontal displacement vector, stratified sound speed, and its gradient vector. We numerically investigated the best arrangement by evaluating the condition number of the observation equations. For further application, we also diagnosed the case of the reduced number of the unknowns and transponders for lower-cost construction of

  11. A Fusion Model of Seismic and Hydro-Acoustic Propagation for Treaty Monitoring

    NASA Astrophysics Data System (ADS)

    Arora, Nimar; Prior, Mark

    2014-05-01

    We present an extension to NET-VISA (Network Processing Vertically Integrated Seismic Analysis), which is a probabilistic generative model of the propagation of seismic waves and their detection on a global scale, to incorporate hydro-acoustic data from the IMS (International Monitoring System) network. The new model includes the coupling of seismic waves into the ocean's SOFAR channel, as well as the propagation of hydro-acoustic waves from underwater explosions. The generative model is described in terms of multiple possible hypotheses -- seismic-to-hydro-acoustic, under-water explosion, other noise sources such as whales singing or icebergs breaking up -- that could lead to signal detections. We decompose each hypothesis into conditional probability distributions that are carefully analyzed and calibrated. These distributions include ones for detection probabilities, blockage in the SOFAR channel (including diffraction, refraction, and reflection around obstacles), energy attenuation, and other features of the resulting waveforms. We present a study of the various features that are extracted from the hydro-acoustic waveforms, and their correlations with each other as well the source of the energy. Additionally, an inference algorithm is presented that concurrently infers the seismic and under-water events, and associates all arrivals (aka triggers), both from seismic and hydro-acoustic stations, to the appropriate event, and labels the path taken by the wave. Finally, our results demonstrate that this fusion of seismic and hydro-acoustic data leads to very good performance. A majority of the under-water events that IDC (International Data Center) analysts built in 2010 are correctly located, and the arrivals that correspond to seismic-to-hydroacoustic coupling, the T phases, are mostly correctly identified. There is no loss in the accuracy of seismic events, in fact, there is a slight overall improvement.

  12. Laser photoacoustic technique for ultrasonic surface acoustic wave velocity evaluation on porcelain

    NASA Astrophysics Data System (ADS)

    Qian, K.; Tu, S. J.; Gao, L.; Xu, J.; Li, S. D.; Yu, W. C.; Liao, H. H.

    2016-10-01

    A laser photoacoustic technique has been developed to evaluate the surface acoustic wave (SAW) velocity of porcelain. A Q-switched Nd:YAG laser at 1064 nm was focused by a cylindrical lens to initiate broadband SAW impulses, which were detected by an optical fiber interferometer with high spatial resolution. Multiple near-field surface acoustic waves were observed on the sample surface at various locations along the axis perpendicular to the laser line source as the detector moved away from the source in the same increments. The frequency spectrum and dispersion curves were obtained by operating on the recorded waveforms with cross-correlation and FFT. The SAW phase velocities of the porcelain of the same source are similar while they are different from those of different sources. The marked differences of Rayleigh phase velocities in our experiment suggest that this technique has the potential for porcelain identification.

  13. On measurement of the acoustic nonlinearity parameter using the finite amplitude insertion substitution (FAIS) technique

    NASA Astrophysics Data System (ADS)

    Zeqiri, Bajram; Cook, Ashley; Rétat, Lise; Civale, John; ter Haar, Gail

    2015-04-01

    The acoustic nonlinearity parameter, B/A, is an important parameter which defines the way a propagating finite amplitude acoustic wave progressively distorts when travelling through any medium. One measurement technique used to determine its value is the finite amplitude insertion substitution (FAIS) method which has been applied to a range of liquid, tissue and tissue-like media. Importantly, in terms of the achievable measurement uncertainties, it is a relative technique. This paper presents a detailed study of the method, employing a number of novel features. The first of these is the use of a large area membrane hydrophone (30 mm aperture) which is used to record the plane-wave component of the acoustic field. This reduces the influence of diffraction on measurements, enabling studies to be carried out within the transducer near-field, with the interrogating transducer, test cell and detector positioned close to one another, an attribute which assists in controlling errors arising from nonlinear distortion in any intervening water path. The second feature is the development of a model which estimates the influence of finite-amplitude distortion as the acoustic wave travels from the rear surface of the test cell to the detector. It is demonstrated that this can lead to a significant systematic error in B/A measurement whose magnitude and direction depends on the acoustic property contrast between the test material and the water-filled equivalent cell. Good qualitative agreement between the model and experiment is reported. B/A measurements are reported undertaken at (20 ± 0.5) °C for two fluids commonly employed as reference materials within the technical literature: Corn Oil and Ethylene Glycol. Samples of an IEC standardised agar-based tissue-mimicking material were also measured. A systematic assessment of measurement uncertainties is presented giving expanded uncertainties in the range ±7% to ±14%, expressed at a confidence level close to 95

  14. Bulk microstructure and local elastic properties of carbon nanocomposites studied by impulse acoustic microscopy technique

    NASA Astrophysics Data System (ADS)

    Levin, V.; Petronyuk, Yu.; Morokov, E.; Chernozatonskii, L.; Kuzhir, P.; Fierro, V.; Celzard, A.; Bellucci, S.; Bistarelli, S.; Mastrucci, M.; Tabacchioni, I.

    2016-05-01

    Bulk microstructure and elastic properties of epoxy-nanocarbon nanocomposites for diverse types and different content of carbon nanofiller has been studied by using impulse acoustic microscopy technique. It has been shown occurrence of various types of mesoscopic structure formed by nanoparticles inside the bulk of nanocomposite materials, including nanoparticle conglomerates and nanoparticle aerogel systems. In spite of the bulk microstructure, nanocarbon composites demonstrate elastic uniformity and negligible influence of nanofiller on elastic properties of carbon nanocomposite materials.

  15. A functional technique based on the Euclidean algorithm with applications to 2-D acoustic diffractal diffusers

    NASA Astrophysics Data System (ADS)

    Cortés-Vega, Luis

    2015-09-01

    We built, based on the Euclidean algorithm, a functional technique, which allows to discover a direct proof of Chinese Remainder Theorem. Afterwards, by using this functional approach, we present some applications to 2-D acoustic diffractal diffusers. The novelty of the method is their functional algorithmic character, which improves ideas, as well as, other results of the author and his collaborators in a previous work.

  16. Theoretical detection threshold of the proton-acoustic range verification technique

    PubMed Central

    Ahmad, Moiz; Xiang, Liangzhong; Yousefi, Siavash; Xing, Lei

    2015-01-01

    Purpose: Range verification in proton therapy using the proton-acoustic signal induced in the Bragg peak was investigated for typical clinical scenarios. The signal generation and detection processes were simulated in order to determine the signal-to-noise limits. Methods: An analytical model was used to calculate the dose distribution and local pressure rise (per proton) for beams of different energy (100 and 160 MeV) and spot widths (1, 5, and 10 mm) in a water phantom. In this method, the acoustic waves propagating from the Bragg peak were generated by the general 3D pressure wave equation implemented using a finite element method. Various beam pulse widths (0.1–10 μs) were simulated by convolving the acoustic waves with Gaussian kernels. A realistic PZT ultrasound transducer (5 cm diameter) was simulated with a Butterworth bandpass filter with consideration of random noise based on a model of thermal noise in the transducer. The signal-to-noise ratio on a per-proton basis was calculated, determining the minimum number of protons required to generate a detectable pulse. The maximum spatial resolution of the proton-acoustic imaging modality was also estimated from the signal spectrum. Results: The calculated noise in the transducer was 12–28 mPa, depending on the transducer central frequency (70–380 kHz). The minimum number of protons detectable by the technique was on the order of 3–30 × 106 per pulse, with 30–800 mGy dose per pulse at the Bragg peak. Wider pulses produced signal with lower acoustic frequencies, with 10 μs pulses producing signals with frequency less than 100 kHz. Conclusions: The proton-acoustic process was simulated using a realistic model and the minimal detection limit was established for proton-acoustic range validation. These limits correspond to a best case scenario with a single large detector with no losses and detector thermal noise as the sensitivity limiting factor. Our study indicated practical proton-acoustic range

  17. Theoretical detection threshold of the proton-acoustic range verification technique

    SciTech Connect

    Ahmad, Moiz; Yousefi, Siavash; Xing, Lei; Xiang, Liangzhong

    2015-10-15

    Purpose: Range verification in proton therapy using the proton-acoustic signal induced in the Bragg peak was investigated for typical clinical scenarios. The signal generation and detection processes were simulated in order to determine the signal-to-noise limits. Methods: An analytical model was used to calculate the dose distribution and local pressure rise (per proton) for beams of different energy (100 and 160 MeV) and spot widths (1, 5, and 10 mm) in a water phantom. In this method, the acoustic waves propagating from the Bragg peak were generated by the general 3D pressure wave equation implemented using a finite element method. Various beam pulse widths (0.1–10 μs) were simulated by convolving the acoustic waves with Gaussian kernels. A realistic PZT ultrasound transducer (5 cm diameter) was simulated with a Butterworth bandpass filter with consideration of random noise based on a model of thermal noise in the transducer. The signal-to-noise ratio on a per-proton basis was calculated, determining the minimum number of protons required to generate a detectable pulse. The maximum spatial resolution of the proton-acoustic imaging modality was also estimated from the signal spectrum. Results: The calculated noise in the transducer was 12–28 mPa, depending on the transducer central frequency (70–380 kHz). The minimum number of protons detectable by the technique was on the order of 3–30 × 10{sup 6} per pulse, with 30–800 mGy dose per pulse at the Bragg peak. Wider pulses produced signal with lower acoustic frequencies, with 10 μs pulses producing signals with frequency less than 100 kHz. Conclusions: The proton-acoustic process was simulated using a realistic model and the minimal detection limit was established for proton-acoustic range validation. These limits correspond to a best case scenario with a single large detector with no losses and detector thermal noise as the sensitivity limiting factor. Our study indicated practical proton-acoustic

  18. Monitoring Thermal Fatigue Damage In Nuclear Power Plant Materials Using Acoustic Emission

    SciTech Connect

    Meyer, Ryan M.; Ramuhalli, Pradeep; Watson, Bruce E.; Pitman, Stan G.; Roosendaal, Timothy J.; Bond, Leonard J.

    2012-04-26

    Proactive aging management of nuclear power plant passive components requires technologies to enable monitoring and accurate quantification of material condition at early stages of degradation (i.e., pre-macrocrack). Acoustic emission (AE) is well-suited to continuous monitoring of component degradation and is proposed as a method to monitor degradation during accelerated thermal fatigue tests. A key consideration is the ability to separate degradation responses from external sources such as water spray induced during thermal fatigue testing. Water spray provides a significant background of acoustic signals, which can overwhelm AE signals caused by degradation. Analysis of AE signal frequency and energy is proposed in this work as a means for separating degradation signals from background sources. Encouraging results were obtained by applying both frequency and energy filters to preliminary data. The analysis of signals filtered using frequency and energy provides signatures exhibiting several characteristics that are consistent with degradation accumulation in materials. Future work is planned to enable verification of the efficacy of AE for thermal fatigue crack initiation detection. While the emphasis has been placed on the use of AE for crack initiation detection during accelerated aging tests, this work also has implications with respect to the use of AE as a primary tool for early degradation monitoring in nuclear power plant materials. The development of NDE tools for characterization of aging in materials can also benefit from the use of a technology such as AE which can continuously monitor and detect crack initiation during accelerated aging tests.

  19. A Device for Fetal Monitoring by Means of Control Over Cardiovascular Parameters Based on Acoustic Data

    NASA Astrophysics Data System (ADS)

    Khokhlova, L. A.; Seleznev, A. I.; Zhdanov, D. S.; Zemlyakov, I. Yu; Kiseleva, E. Yu

    2016-01-01

    The problem of monitoring fetal health is topical at the moment taking into account a reduction in the level of fertile-age women's health and changes in the concept of perinatal medicine with reconsideration of live birth criteria. Fetal heart rate monitoring is a valuable means of assessing fetal health during pregnancy. The routine clinical measurements are usually carried out by the means of ultrasound cardiotocography. Although the cardiotocography monitoring provides valuable information on the fetal health status, the high quality ultrasound devices are expensive, they are not available for home care use. The recommended number of measurement is also limited. The passive and fully non-invasive acoustic recording provides an alternative low-cost measurement method. The article describes a device for fetal and maternal health monitoring by analyzing the frequency and periodicity of heart beats by means of acoustic signal received on the maternal abdomen. Based on the usage of this device a phonocardiographic fetal telemedicine system, which will allow to reduce the antenatal fetal mortality rate significantly due to continuous monitoring over the state of fetus regardless of mother's location, can be built.

  20. Crack Propagation Analysis Using Acoustic Emission Sensors for Structural Health Monitoring Systems

    DOE PAGES

    Kral, Zachary; Horn, Walter; Steck, James

    2013-01-01

    Aerospace systems are expected to remain in service well beyond their designed life. Consequently, maintenance is an important issue. A novel method of implementing artificial neural networks and acoustic emission sensors to form a structural health monitoring (SHM) system for aerospace inspection routines was the focus of this research. Simple structural elements, consisting of flat aluminum plates of AL 2024-T3, were subjected to increasing static tensile loading. As the loading increased, designed cracks extended in length, releasing strain waves in the process. Strain wave signals, measured by acoustic emission sensors, were further analyzed in post-processing by artificial neural networks (ANN).more » Several experiments were performed to determine the severity and location of the crack extensions in the structure. ANNs were trained on a portion of the data acquired by the sensors and the ANNs were then validated with the remaining data. The combination of a system of acoustic emission sensors, and an ANN could determine crack extension accurately. The difference between predicted and actual crack extensions was determined to be between 0.004 in. and 0.015 in. with 95% confidence. These ANNs, coupled with acoustic emission sensors, showed promise for the creation of an SHM system for aerospace systems.« less

  1. Dual instrument passive acoustic monitoring of belugas in Cook Inlet, Alaska.

    PubMed

    Castellote, Manuel; Small, Robert J; Lammers, Marc O; Jenniges, Justin J; Mondragon, Jeff; Atkinson, Shannon

    2016-05-01

    As part of a long-term research program, Cook Inlet beluga (Delphinapterus leucas) presence was acoustically monitored with two types of acoustic sensors utilized in tandem in moorings deployed year-round: an ecological acoustic recorder (EAR) and a cetacean and porpoise detector (C-POD). The EAR was used primarily to record the calls, whistles, and buzzes produced by belugas and killer whales (Orcinus orca). The C-POD was used to log and classify echolocation clicks from belugas, killer whales, and porpoises. This paper describes mooring packages that maximized the chances of successful long-term data collection in the particularly challenging Cook Inlet environment, and presents an analytical comparison of odontocete detections obtained by the collocated EAR and C-POD instruments from two mooring locations in the upper inlet. Results from this study illustrate a significant improvement in detecting beluga and killer whale presence when the different acoustic signals detected by EARs and C-PODs are considered together. Further, results from concurrent porpoise detections indicating prey competition and feeding interference with beluga, and porpoise displacement due to ice formation are described. PMID:27250163

  2. Crack Propagation Analysis Using Acoustic Emission Sensors for Structural Health Monitoring Systems

    PubMed Central

    Horn, Walter; Steck, James

    2013-01-01

    Aerospace systems are expected to remain in service well beyond their designed life. Consequently, maintenance is an important issue. A novel method of implementing artificial neural networks and acoustic emission sensors to form a structural health monitoring (SHM) system for aerospace inspection routines was the focus of this research. Simple structural elements, consisting of flat aluminum plates of AL 2024-T3, were subjected to increasing static tensile loading. As the loading increased, designed cracks extended in length, releasing strain waves in the process. Strain wave signals, measured by acoustic emission sensors, were further analyzed in post-processing by artificial neural networks (ANN). Several experiments were performed to determine the severity and location of the crack extensions in the structure. ANNs were trained on a portion of the data acquired by the sensors and the ANNs were then validated with the remaining data. The combination of a system of acoustic emission sensors, and an ANN could determine crack extension accurately. The difference between predicted and actual crack extensions was determined to be between 0.004 in. and 0.015 in. with 95% confidence. These ANNs, coupled with acoustic emission sensors, showed promise for the creation of an SHM system for aerospace systems. PMID:24023536

  3. Crack propagation analysis using acoustic emission sensors for structural health monitoring systems.

    PubMed

    Kral, Zachary; Horn, Walter; Steck, James

    2013-01-01

    Aerospace systems are expected to remain in service well beyond their designed life. Consequently, maintenance is an important issue. A novel method of implementing artificial neural networks and acoustic emission sensors to form a structural health monitoring (SHM) system for aerospace inspection routines was the focus of this research. Simple structural elements, consisting of flat aluminum plates of AL 2024-T3, were subjected to increasing static tensile loading. As the loading increased, designed cracks extended in length, releasing strain waves in the process. Strain wave signals, measured by acoustic emission sensors, were further analyzed in post-processing by artificial neural networks (ANN). Several experiments were performed to determine the severity and location of the crack extensions in the structure. ANNs were trained on a portion of the data acquired by the sensors and the ANNs were then validated with the remaining data. The combination of a system of acoustic emission sensors, and an ANN could determine crack extension accurately. The difference between predicted and actual crack extensions was determined to be between 0.004 in. and 0.015 in. with 95% confidence. These ANNs, coupled with acoustic emission sensors, showed promise for the creation of an SHM system for aerospace systems. PMID:24023536

  4. Acoustic Measurements in Opera Houses: Comparison Between Different Techniques and Equipment

    NASA Astrophysics Data System (ADS)

    FAUSTI, P.; FARINA, A.

    2000-04-01

    In room acoustics, many objective parameters to quantify subjective impressions have been introduced. These quantities can be measured by using a wide variety of powerful tools and equipment. The results can be influenced by the measurement techniques and instruments used. Furthermore, the results also depend on the measurement positions and on the condition of the hall (full, empty, etc.). The aim of this work is to define a tightly standardized measurement procedure for the collection of a complete objective description of an opera house's acoustics. In this paper some of the results obtained by the authors after measurements made in three different halls are presented. Comparisons were made both between different hardware and software tools (real-time analyzer, DAT, PC-board, source, microphones, post-processing software) and between different measurement methods (interrupted stationary noise, true-impulse, pseudo-random white noise with impulse-response doconvolution, sine sweep) as well as between different positions in the halls, with and without the presence of musicians and audience. The results have shown that the differences obtained when using different measurement techniques and equipment are not of significant importance. The only effective differences were found regarding the recording techniques, as the monaural measurements give appreciably different results from the average of left and right channel of binaural measurements. Slightly different results were alsofound between true impulsive sources (pistol shots, balloons) and omni-directional (dodecahedral) loudspeakers. Attention must be paid to the signal-to-noise ratio, as this can influence the correct calculation of some acoustical parameters. Some differences, not as great as expected, were found in the results with and without the musicians in the orchestra shell and with and without the audience in the hall. This is probably due to the high sound absorption that is typical in Italian opera

  5. Monitoring Anthropogenic Ocean Sound from Shipping Using an Acoustic Sensor Network and a Compressive Sensing Approach.

    PubMed

    Harris, Peter; Philip, Rachel; Robinson, Stephen; Wang, Lian

    2016-03-22

    Monitoring ocean acoustic noise has been the subject of considerable recent study, motivated by the desire to assess the impact of anthropogenic noise on marine life. A combination of measuring ocean sound using an acoustic sensor network and modelling sources of sound and sound propagation has been proposed as an approach to estimating the acoustic noise map within a region of interest. However, strategies for developing a monitoring network are not well established. In this paper, considerations for designing a network are investigated using a simulated scenario based on the measurement of sound from ships in a shipping lane. Using models for the sources of the sound and for sound propagation, a noise map is calculated and measurements of the noise map by a sensor network within the region of interest are simulated. A compressive sensing algorithm, which exploits the sparsity of the representation of the noise map in terms of the sources, is used to estimate the locations and levels of the sources and thence the entire noise map within the region of interest. It is shown that although the spatial resolution to which the sound sources can be identified is generally limited, estimates of aggregated measures of the noise map can be obtained that are more reliable compared with those provided by other approaches.

  6. Deep-water riser fatigue monitoring systems based on acoustic telemetry

    NASA Astrophysics Data System (ADS)

    Li, Baojun; Wang, Haiyan; Shen, Xiaohong; Yan, Yongsheng; Yang, Fuzhou; Hua, Fei

    2014-12-01

    Marine risers play a key role in the deep and ultra-deep water oil and gas production. The vortex-induced vibration (VIV) of marine risers constitutes an important problem in deep water oil exploration and production. VIV will result in high rates of structural failure of marine riser due to fatigue damage accumulation and diminishes the riser fatigue life. In-service monitoring or full scale testing is essential to improve our understanding of VIV response and enhance our ability to predict fatigue damage. One marine riser fatigue acoustic telemetry scheme is proposed and an engineering prototype machine has been developed to monitor deep and ultra-deep water risers' fatigue and failure that can diminish the riser fatigue life and lead to economic losses and eco-catastrophe. Many breakthroughs and innovation have been achieved in the process of developing an engineering prototype machine. Sea trials were done on the 6th generation deep-water drilling platform HYSY-981 in the South China Sea. The inclination monitoring results show that the marine riser fatigue acoustic telemetry scheme is feasible and reliable and the engineering prototype machine meets the design criterion and can match the requirements of deep and ultra-deep water riser fatigue monitoring. The rich experience and field data gained in the sea trial which provide much technical support for optimization in the engineering prototype machine in the future.

  7. Acoustic signature recognition technique for Human-Object Interactions (HOI) in persistent surveillance systems

    NASA Astrophysics Data System (ADS)

    Alkilani, Amjad; Shirkhodaie, Amir

    2013-05-01

    Handling, manipulation, and placement of objects, hereon called Human-Object Interaction (HOI), in the environment generate sounds. Such sounds are readily identifiable by the human hearing. However, in the presence of background environment noises, recognition of minute HOI sounds is challenging, though vital for improvement of multi-modality sensor data fusion in Persistent Surveillance Systems (PSS). Identification of HOI sound signatures can be used as precursors to detection of pertinent threats that otherwise other sensor modalities may miss to detect. In this paper, we present a robust method for detection and classification of HOI events via clustering of extracted features from training of HOI acoustic sound waves. In this approach, salient sound events are preliminary identified and segmented from background via a sound energy tracking method. Upon this segmentation, frequency spectral pattern of each sound event is modeled and its features are extracted to form a feature vector for training. To reduce dimensionality of training feature space, a Principal Component Analysis (PCA) technique is employed to expedite fast classification of test feature vectors, a kd-tree and Random Forest classifiers are trained for rapid classification of training sound waves. Each classifiers employs different similarity distance matching technique for classification. Performance evaluations of classifiers are compared for classification of a batch of training HOI acoustic signatures. Furthermore, to facilitate semantic annotation of acoustic sound events, a scheme based on Transducer Mockup Language (TML) is proposed. The results demonstrate the proposed approach is both reliable and effective, and can be extended to future PSS applications.

  8. Fabrication of Capacitive Acoustic Resonators Combining 3D Printing and 2D Inkjet Printing Techniques

    PubMed Central

    Haque, Rubaiyet Iftekharul; Ogam, Erick; Loussert, Christophe; Benaben, Patrick; Boddaert, Xavier

    2015-01-01

    A capacitive acoustic resonator developed by combining three-dimensional (3D) printing and two-dimensional (2D) printed electronics technique is described. During this work, a patterned bottom structure with rigid backplate and cavity is fabricated directly by a 3D printing method, and then a direct write inkjet printing technique has been employed to print a silver conductive layer. A novel approach has been used to fabricate a diaphragm for the acoustic sensor as well, where the conductive layer is inkjet-printed on a pre-stressed thin organic film. After assembly, the resulting structure contains an electrically conductive diaphragm positioned at a distance from a fixed bottom electrode separated by a spacer. Measurements confirm that the transducer acts as capacitor. The deflection of the diaphragm in response to the incident acoustic single was observed by a laser Doppler vibrometer and the corresponding change of capacitance has been calculated, which is then compared with the numerical result. Observation confirms that the device performs as a resonator and provides adequate sensitivity and selectivity at its resonance frequency. PMID:26473878

  9. Fabrication of capacitive acoustic resonators combining 3D printing and 2D inkjet printing techniques.

    PubMed

    Haque, Rubaiyet Iftekharul; Ogam, Erick; Loussert, Christophe; Benaben, Patrick; Boddaert, Xavier

    2015-10-14

    A capacitive acoustic resonator developed by combining three-dimensional (3D) printing and two-dimensional (2D) printed electronics technique is described. During this work, a patterned bottom structure with rigid backplate and cavity is fabricated directly by a 3D printing method, and then a direct write inkjet printing technique has been employed to print a silver conductive layer. A novel approach has been used to fabricate a diaphragm for the acoustic sensor as well, where the conductive layer is inkjet-printed on a pre-stressed thin organic film. After assembly, the resulting structure contains an electrically conductive diaphragm positioned at a distance from a fixed bottom electrode separated by a spacer. Measurements confirm that the transducer acts as capacitor. The deflection of the diaphragm in response to the incident acoustic single was observed by a laser Doppler vibrometer and the corresponding change of capacitance has been calculated, which is then compared with the numerical result. Observation confirms that the device performs as a resonator and provides adequate sensitivity and selectivity at its resonance frequency.

  10. Acoustic Biometric System Based on Preprocessing Techniques and Linear Support Vector Machines.

    PubMed

    del Val, Lara; Izquierdo-Fuente, Alberto; Villacorta, Juan J; Raboso, Mariano

    2015-06-17

    Drawing on the results of an acoustic biometric system based on a MSE classifier, a new biometric system has been implemented. This new system preprocesses acoustic images, extracts several parameters and finally classifies them, based on Support Vector Machine (SVM). The preprocessing techniques used are spatial filtering, segmentation-based on a Gaussian Mixture Model (GMM) to separate the person from the background, masking-to reduce the dimensions of images-and binarization-to reduce the size of each image. An analysis of classification error and a study of the sensitivity of the error versus the computational burden of each implemented algorithm are presented. This allows the selection of the most relevant algorithms, according to the benefits required by the system. A significant improvement of the biometric system has been achieved by reducing the classification error, the computational burden and the storage requirements.

  11. Acoustic levitation technique for containerless processing at high temperatures in space

    NASA Technical Reports Server (NTRS)

    Rey, Charles A.; Merkley, Dennis R.; Hammarlund, Gregory R.; Danley, Thomas J.

    1988-01-01

    High temperature processing of a small specimen without a container has been demonstrated in a set of experiments using an acoustic levitation furnace in the microgravity of space. This processing technique includes the positioning, heating, melting, cooling, and solidification of a material supported without physical contact with container or other surface. The specimen is supported in a potential energy well, created by an acoustic field, which is sufficiently strong to position the specimen in the microgravity environment of space. This containerless processing apparatus has been successfully tested on the Space Shuttle during the STS-61A mission. In that experiment, three samples wer successfully levitated and processed at temperatures from 600 to 1500 C. Experiment data and results are presented.

  12. Acoustic emission: Towards a real-time diagnosis technique for Proton Exchange Membrane Fuel Cell operation

    NASA Astrophysics Data System (ADS)

    Legros, B.; Thivel, P.-X.; Bultel, Y.; Boinet, M.; Nogueira, R. P.

    This paper deals with one of the needs for PEMFC to be economically reliable: diagnosis tool for water management. This issue is actually a key parameter for both performance and durability improvement. Acoustic emission (AE) technique was employed to survey PEM single cell under various operating conditions. AE events coming from different sources have thus been identified, classified and finally ascribed to different phenomena induced by MEA water uptake and/or biphasic flow in the gas channel thanks to a statistical post-treatment of the acoustic data. Results, although qualitative, seems trusty enough to unravel hidden correlations between AE hits and physicochemical phenomena taking place during the cell operation and open up the way for an innovative and non-invasive online diagnosis tool.

  13. Acoustic Biometric System Based on Preprocessing Techniques and Linear Support Vector Machines

    PubMed Central

    del Val, Lara; Izquierdo-Fuente, Alberto; Villacorta, Juan J.; Raboso, Mariano

    2015-01-01

    Drawing on the results of an acoustic biometric system based on a MSE classifier, a new biometric system has been implemented. This new system preprocesses acoustic images, extracts several parameters and finally classifies them, based on Support Vector Machine (SVM). The preprocessing techniques used are spatial filtering, segmentation—based on a Gaussian Mixture Model (GMM) to separate the person from the background, masking—to reduce the dimensions of images—and binarization—to reduce the size of each image. An analysis of classification error and a study of the sensitivity of the error versus the computational burden of each implemented algorithm are presented. This allows the selection of the most relevant algorithms, according to the benefits required by the system. A significant improvement of the biometric system has been achieved by reducing the classification error, the computational burden and the storage requirements. PMID:26091392

  14. Leak detection by acoustic emissions monitoring: An experimental investigation of the acoustic properties of leaks and the attenuation characteristics of soil

    SciTech Connect

    Kilpatrick, J.F.; March, P.A.

    1994-05-27

    This study experimentally explored the conditions, equipment, and methodology necessary for the acoustic detection of small leaks of jet fuel (JP4) from underground storage tank (UST) systems. The study indicates that acoustic leak detection of very small leaks is feasible. In general, significant JP4 fuel leaks which occur across a 5 PSI (pounds per square inch) or greater pressure drop are acoustically active and can be detected with proper sensors and proper placement of sensors. The primary source of leak noise is turbulent flow through the leak orifice. At lower pressures, the leak flow becomes laminar, and the leak becomes virtually silent. With direct transducer contact on the pipe or tank wall and sufficient system pressure, leaks smaller than 0.1 GPH (gallons per hour) can be detected. Larger leaks can be detected through short distances in soil. However, sand, which is the most commonly used fill material for UST systems, provides significant acoustic attenuation. Consequently, waveguides must be used when monitoring distances exceeding about 1 foot of travel through sand. Sand acts to reduce background noise levels, providing an ideal environment for acoustic leak detection using sensors mounted directly on the pipe or tank wall. Leak detection, Acoustics, Underground storage tanks, Pipelines, Attenuation.

  15. Video and acoustic camera techniques for studying fish under ice: a review and comparison

    SciTech Connect

    Mueller, Robert P.; Brown, Richard S.; Hop, Haakon H.; Moulton, Larry

    2006-09-05

    Researchers attempting to study the presence, abundance, size, and behavior of fish species in northern and arctic climates during winter face many challenges, including the presence of thick ice cover, snow cover, and, sometimes, extremely low temperatures. This paper describes and compares the use of video and acoustic cameras for determining fish presence and behavior in lakes, rivers, and streams with ice cover. Methods are provided for determining fish density and size, identifying species, and measuring swimming speed and successful applications of previous surveys of fish under the ice are described. These include drilling ice holes, selecting batteries and generators, deploying pan and tilt cameras, and using paired colored lasers to determine fish size and habitat associations. We also discuss use of infrared and white light to enhance image-capturing capabilities, deployment of digital recording systems and time-lapse techniques, and the use of imaging software. Data are presented from initial surveys with video and acoustic cameras in the Sagavanirktok River Delta, Alaska, during late winter 2004. These surveys represent the first known successful application of a dual-frequency identification sonar (DIDSON) acoustic camera under the ice that achieved fish detection and sizing at camera ranges up to 16 m. Feasibility tests of video and acoustic cameras for determining fish size and density at various turbidity levels are also presented. Comparisons are made of the different techniques in terms of suitability for achieving various fisheries research objectives. This information is intended to assist researchers in choosing the equipment that best meets their study needs.

  16. Monitoring of Concrete Structures Using Ofdr Technique

    NASA Astrophysics Data System (ADS)

    Henault, J. M.; Salin, J.; Moreau, G.; Delepine-Lesoille, S.; Bertand, J.; Taillade, F.; Quiertant, M.; Benzarti, K.

    2011-06-01

    Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as bridges, dikes, nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on Optical Frequency Domain Reflectometry (OFDR), enables to perform temperature and strain measurements with a centimeter scale spatial resolution over hundred of meters and with a level of precision equal to 1 μstrain and 0.1 °C. Several sensing cables are designed with different materials targeting to last for decades in a concrete aggressive environment and to ensure an optimal transfer of temperature and strain from the concrete matrix to the optical fiber. Tests were carried out by embedding various sensing cables into plain concrete specimens and representative-scale reinforced concrete structural elements. Measurements were performed with an OFDR instrument; meanwhile, mechanical solicitations were imposed to the concrete element. Preliminary experiments are very promising since measurements performed with distributed sensing system are comparable to values obtained with conventional sensors used in civil engineering and with the Strength of Materials Modelling. Moreover, the distributed sensing system makes it possible to detect and localize cracks appearing in concrete during the mechanical loading.

  17. Method and apparatus for acoustically monitoring the flow of suspended solid particulate matter

    DOEpatents

    Roach, Paul D.; Raptis, Apostolos C.

    1982-01-01

    A method and apparatus for monitoring char flow in a coal gasifier system cludes flow monitor circuits which measure acoustic attenuation caused by the presence of char in a char line and provide a char flow/no flow indication and an indication of relative char density. The flow monitor circuits compute the ratio of signals in two frequency bands, a first frequency band representative of background noise, and a second higher frequency band in which background noise is attenuated by the presence of char. Since the second frequency band contains higher frequencies, the ratio can be used to provide a flow/no flow indication. The second band can also be selected so that attenuation is monotonically related to particle concentration, providing a quantitative measure of char concentration.

  18. In Situ Monitoring of Plasma Spraying Process by Laser Acoustic Emission Method

    NASA Astrophysics Data System (ADS)

    Ito, Kaita; Enoki, Manabu; Watanabe, Makoto; Kuroda, Seiji

    Estimation of microfractures in ceramic coating layer during plasma spraying process is critical for its reliability. Acoustic emission (AE) method enables in-process monitoring of such microfractures. Laser AE method was adopted to realize the monitoring of plasma spraying process by non-contact detection of AE with laser interferometer. Also a high performance method for noise reduction of laser AE waveform was investigated. In this new method, laser AE signal was continuously sampled and transformed into spectrogram by time-frequency analysis to cut out noise component effectively. After this noise reduction process, inverse transform was applied to obtain a clear AE signals in time domain. Whole these processes can be done in real time. The effectiveness of this method was confirmed by a detection test of simulated AE and successfully applied to the monitoring of plasma spraying process. Two types of AE events with different duration time range were found and the sources of these AE were presumed.

  19. Optical and acoustical monitoring of femtosecond laser-induced intracellular contrast agents: initial cell culture studies

    NASA Astrophysics Data System (ADS)

    Zohdy, Marwa J.; Tse, Christine; Ye, Jing Yong; Balogh, Lajos P.; Norris, Theodore B.; O'Donnell, Matthew

    2005-04-01

    Acoustical monitoring of laser-induced optical breakdown can be used as an important tool for diagnostics and therapeutics in living cells. Laser-induced intracellular microbubbles provide measurable contrast when detected with high-frequency ultrasound, and the bioeffects of these bubbles can be controlled to be within two distinct regimes. In the nondestructive regime, a single, transient, detectable bubble can be generated within a cell, without affecting its viability. In the destructive regime, the induced photodisruption can kill a target cell. To generate and monitor this range of effects in real time, we have developed a system integrating a femtosecond pulsed laser source with optical and acoustical microscopy. Experiments were performed on monolayers of Chinese hamster ovary cells. A Ti:Sapphire laser (793 nm wavelength, 100 fs pulse duration) was pulsed at 3.8 kHz and tightly focused to a 1 μm spot within each cell, and a high-frequency (50 MHz) ultrasonic transducer monitored the generated bubble with continuous pulse-echo recordings. The photodisruption was also observed with bright field optical microscopy, and cell viability was assessed after laser exposure using a colorimetric live/dead stain. By controlling laser pulse fluence, exposure duration, and the intracellular location of the laser focus, either nondestructive or destructive bubbles could be generated.

  20. Comparing Distribution of Harbour Porpoises (Phocoena phocoena) Derived from Satellite Telemetry and Passive Acoustic Monitoring.

    PubMed

    Mikkelsen, Lonnie; Rigét, Frank F; Kyhn, Line A; Sveegaard, Signe; Dietz, Rune; Tougaard, Jakob; Carlström, Julia A K; Carlén, Ida; Koblitz, Jens C; Teilmann, Jonas

    2016-01-01

    Cetacean monitoring is essential in determining the status of a population. Different monitoring methods should reflect the real trends in abundance and patterns in distribution, and results should therefore ideally be independent of the selected method. Here, we compare two independent methods of describing harbour porpoise (Phocoena phocoena) relative distribution pattern in the western Baltic Sea. Satellite locations from 13 tagged harbour porpoises were used to build a Maximum Entropy (MaxEnt) model of suitable habitats. The data set was subsampled to one location every second day, which were sufficient to make reliable models over the summer (Jun-Aug) and autumn (Sep-Nov) seasons. The modelled results were compared to harbour porpoise acoustic activity obtained from 36 static acoustic monitoring stations (C-PODs) covering the same area. The C-POD data was expressed as the percentage of porpoise positive days/hours (the number of days/hours per day with porpoise detections) by season. The MaxEnt model and C-POD data showed a significant linear relationship with a strong decline in porpoise occurrence from west to east. This study shows that two very different methods provide comparable information on relative distribution patterns of harbour porpoises even in a low density area. PMID:27463509

  1. Comparing Distribution of Harbour Porpoises (Phocoena phocoena) Derived from Satellite Telemetry and Passive Acoustic Monitoring

    PubMed Central

    Rigét, Frank F.; Kyhn, Line A.; Sveegaard, Signe; Dietz, Rune; Tougaard, Jakob; Carlström, Julia A. K.; Carlén, Ida; Koblitz, Jens C.; Teilmann, Jonas

    2016-01-01

    Cetacean monitoring is essential in determining the status of a population. Different monitoring methods should reflect the real trends in abundance and patterns in distribution, and results should therefore ideally be independent of the selected method. Here, we compare two independent methods of describing harbour porpoise (Phocoena phocoena) relative distribution pattern in the western Baltic Sea. Satellite locations from 13 tagged harbour porpoises were used to build a Maximum Entropy (MaxEnt) model of suitable habitats. The data set was subsampled to one location every second day, which were sufficient to make reliable models over the summer (Jun-Aug) and autumn (Sep-Nov) seasons. The modelled results were compared to harbour porpoise acoustic activity obtained from 36 static acoustic monitoring stations (C-PODs) covering the same area. The C-POD data was expressed as the percentage of porpoise positive days/hours (the number of days/hours per day with porpoise detections) by season. The MaxEnt model and C-POD data showed a significant linear relationship with a strong decline in porpoise occurrence from west to east. This study shows that two very different methods provide comparable information on relative distribution patterns of harbour porpoises even in a low density area. PMID:27463509

  2. Acoustic Monitor for Liquid-Solid Slurries Measurements at Low Weight Fractions

    SciTech Connect

    Tavlarides, Lawrence L.

    2005-06-01

    Our effort in this project is to develop an acoustic monitor for accurate, real-time characterization of the size and weight fractions of solids in slurries for process monitoring and to determine the optimal timing for slurry transfers. This capability will be valuable in the Savannah River Site accelerated clean-up program. Our scientific work during the first research period developed a theory, supported by experiments, to describe sound attenuation of solids in suspensions in the presence of bubbles, which permits us to determine the solid-liquid weight percent. Engineering developments during the second research period led to the design, construction, and demonstration, in our laboratories, of the Syracuse Acoustic Monitor (SAM) system that measures weight percent solids accurately in slurries of 0.5 to 8.0 weight percent on-line and in real-time. Also, we had shown the potential for these measurements in solid-gas-liquid slurries by removing the interference due to the presence of gas bubbles.

  3. Damage Accumulation in Cyclically-Loaded Glass-Ceramic Matrix Composites Monitored by Acoustic Emission

    PubMed Central

    Aggelis, D. G.; Dassios, K. G.; Kordatos, E. Z.; Matikas, T. E.

    2013-01-01

    Barium osumilite (BMAS) ceramic matrix composites reinforced with SiC-Tyranno fibers are tested in a cyclic loading protocol. Broadband acoustic emission (AE) sensors are used for monitoring the occurrence of different possible damage mechanisms. Improved use of AE indices is proposed by excluding low-severity signals based on waveform parameters, rather than only threshold criteria. The application of such improvements enhances the accuracy of the indices as accumulated damage descriptors. RA-value, duration, and signal energy follow the extension cycles indicating moments of maximum or minimum strain, while the frequency content of the AE signals proves very sensitive to the pull-out mechanism. PMID:24381524

  4. Acoustic monitoring method and system in laser-induced optical breakdown (LIOB)

    DOEpatents

    O'Donnell, Matthew; Ye, Jing Yong; Norris, Theodore B.; Baker, Jr., James R.; Balogh, Lajos P.; Milas, Susanne M.; Emelianov, Stanislav Y.; Hollman, Kyle W.

    2008-05-06

    An acoustic monitoring method and system in laser-induced optical breakdown (LIOB) provides information which characterize material which is broken down, microbubbles in the material, and/or the microenvironment of the microbubbles. In one embodiment of the invention, femtosecond laser pulses are focused just inside the surface of a volume of aqueous solution which may include dendrimer nanocomposite (DNC) particles. A tightly focused, high frequency, single-element ultrasonic transducer is positioned such that its focus coincides axially and laterally with this laser focus. When optical breakdown occurs, a microbubble forms and a shock or pressure wave is emitted (i.e., acoustic emission). In addition to this acoustic signal, the microbubble may be actively probed with pulse-echo measurements from the same transducer. After the microbubble forms, received pulse-echo signals have an extra pulse, describing the microbubble location and providing a measure of axial microbubble size. Wavefield plots of successive recordings illustrate the generation, growth, and collapse of microbubbles due to optical breakdown. These same plots can also be used to quantify LIOB thresholds.

  5. Laser ablation of absorbing liquids under transparent cover: acoustical and optical monitoring

    NASA Astrophysics Data System (ADS)

    Samokhin, A. A.; Il'ichev, N. N.; Pivovarov, P. A.; Sidorin, A. V.

    2016-06-01

    Phase transition induced with infrared (λ = 2920 nm and λ = 2940 nm) nanosecond laser pulses in strongly absorbing liquids (water, ethanol) under transparent solid cover is investigated with the help of acoustical and optical monitoring. LiNbO3 transducer is used for registration of pressure pulses generated in irradiated liquids. Optical signals due to scattering and specular reflection of probing optical beams are explored with the schemes involving total internal reflection and interference effects. Combination of these two optical diagnostic methods permits for the first time to show that irradiation of covered liquids leads to vapor cavity formation which is divided from the cover with thin (submicron) liquid film despite the fact that radiation intensity maximum is located just at the liquid-plate boundary. The cavity formation is due to explosive boiling which occurs when the superheated liquid reaches its superheating limit in near critical region. After the first acoustical signal, the second signal is observed with several hundreds microseconds time delay which is caused by the vapor cavity collapse. Some results of optical and acoustical diagnostics in the case of free liquid surface are also presented.

  6. Temporal isolation of surface-acoustic-wave-driven luminescence from a lateral p n junction using pulsed techniques

    NASA Astrophysics Data System (ADS)

    Gell, J. R.; Ward, M. B.; Atkinson, P.; Bremner, S. P.; Anderson, D.; Norman, C. E.; Kataoka, M.; Barnes, C. H. W.; Jones, G. A. C.; Shields, A. J.; Ritchie, D. A.

    2008-04-01

    The authors report surface-acoustic-wave-driven luminescence from a lateral p-n junction formed by molecular-beam epitaxy regrowth of a modulation doped GaAs/AlGaAs quantum well on a patterned GaAs substrate. Pulsed techniques are used to isolate the surface-acoustic-wave-driven emission from any emission due to pick-up of the free-space electromagnetic wave. The luminescence provides a fast probe of the signals arriving at the p-n junction allowing the response of the junction to the surface-acoustic-wave to be studied in the time domain. Oscillations in the surface-acoustic-wave-driven component of the light intensity are resolved at the resonant frequency of the transducer, suggesting that the surface-acoustic-wave is transporting electrons across the junction in packets.

  7. Acoustic monitoring of laboratory faults: locating the origin of unstable slip events

    NASA Astrophysics Data System (ADS)

    Korkolis, Evangelos; Niemeijer, André; Spiers, Christopher

    2015-04-01

    Over the past several decades, much work has been done on studying the frictional properties of fault gouges at earthquake nucleation velocities. In addition, post-experiment microstructural analyses have been performed in an attempt to link microphysical mechanisms to the observed mechanical data. However, all observations are necessarily post-mortem and it is thus difficult to directly link transients to microstructural characteristics. We are developing an acoustic monitoring system to be used in sliding experiments using a ring shear apparatus. The goal is to locate acoustic emission sources in sheared granular assemblages and link them to processes that act on microstructures responsible for the frictional stability of the simulated fault gouge. The results will be used to develop and constrain microphysical models that explain the relation of these processes to empirical friction laws, such as rate- and state-dependent friction. The acoustic monitoring setup is comprised of an array of 16 piezo-electric sensors installed on the top and bottom sides of an annular sample, at 45 degree intervals. Acoustic emissions associated with slip events can be recorded at sampling rates of up to 50 MHz, in triggered mode. Initial experiments on 0.1 to 0.2 mm and 0.4 to 0.5 mm diameter glass beads, at 1 to 5 MPa normal stress and 1 to 30 um/s load point velocity, have been conducted to estimate the sensitivity of the sensor array. Preliminary results reveal that the intensity of the audible signal is not necessarily proportional to the magnitude of the associated stress drop for constant loading conditions, and that acoustic emissions precede slip events by a small amount of time, in the order of a few milliseconds. Currently, our efforts are focused on developing a suitable source location algorithm with the aim to identify differences in the mode of (unstable) sliding for different types of materials. This will help to identify the micromechanical mechanisms operating

  8. Study of fracture mechanisms of short fiber reinforced AS composite by acoustic emission technique

    SciTech Connect

    Kida, Sotoaki; Suzuki, Megumu

    1995-11-01

    The fracture mechanisms of short fiber reinforced AS composites are studied by acoustic emission technique for examining the effects of fiber contents. The loads P{sub b} and P{sub c} which the damage mechanisms change are obtained at the inflection points of the total AE energy curve the energy gradient method. The damages are generated by fiber breaking at the load point of P{sub b} and P{sub c} in B material, and by the fiber breaking and the debonding between resin and fiber at the load points of P{sub b} and P{sub c} in C material.

  9. Comparison of Acoustic Impedance Eduction Techniques for Locally-Reacting Liners

    NASA Technical Reports Server (NTRS)

    Jones, M. G.; Parrott, T. L.; Watson, W. R.

    2003-01-01

    Typical acoustic liners used in current aircraft inlets and aft-fan ducts consist of some type of perforated facesheet bonded to a honeycomb core. A number of techniques for determining the acoustic impedance of these locallyreacting liners have been developed over the last five decades. In addition, a number of models have been developed to predict the acoustic impedance of locallyreacting liners in the presence of grazing flow, and to use that information together with aeroacoustic propagation codes to assess the noise absorption provided by these liners. These prediction models have incorporated the results from databases acquired with specific impedance eduction techniques. Thus, while these prediction models are acceptable for liners that are similar to those tested in these databases, their application to new liner configurations must be viewed with caution. The primary purpose of this paper is to provide a comparison of impedance eduction techniques that have been implemented at various aerospace research laboratories in the United States (NASA Langley Research Center, General Electric Aircraft Engines, B. F. Goodrich and Boeing). A secondary purpose is to provide data for liner configurations that extend the porosity range beyond that which has been previously used in common aircraft engine nacelles. Two sets of liners were designed to study the effects of three parameters: perforate hole diameter, facesheet thickness and porosity. These two sets of liners were constructed for testing in each of the laboratories listed above. The first set of liners was designed to fit into the NASA Langley and Boeing test facilities. The second set was designed to fit into the General Electric Aircraft Engines and B. F. Goodrich test facilities. By using the same parent material, both sets of liners were identical to within the limits of material and fabrication variability. Baseline data were obtained in the normal incidence impedance tubes at NASA Langley and B. F

  10. Damage characterization in engineering materials using a combination of optical, acoustic, and thermal techniques

    NASA Astrophysics Data System (ADS)

    Tragazikis, I. K.; Exarchos, D. A.; Dalla, P. T.; Matikas, T. E.

    2016-04-01

    This paper deals with the use of complimentary nondestructive methods for the evaluation of damage in engineering materials. The application of digital image correlation (DIC) to engineering materials is a useful tool for accurate, noncontact strain measurement. DIC is a 2D, full-field optical analysis technique based on gray-value digital images to measure deformation, vibration and strain a vast variety of materials. In addition, this technique can be applied from very small to large testing areas and can be used for various tests such as tensile, torsion and bending under static or dynamic loading. In this study, DIC results are benchmarked with other nondestructive techniques such as acoustic emission for damage localization and fracture mode evaluation, and IR thermography for stress field visualization and assessment. The combined use of these three nondestructive methods enables the characterization and classification of damage in materials and structures.

  11. A robust calibration technique for acoustic emission systems based on momentum transfer from a ball drop

    USGS Publications Warehouse

    McLaskey, Gregory C.; Lockner, David A.; Kilgore, Brian D.; Beeler, Nicholas M.

    2015-01-01

    We describe a technique to estimate the seismic moment of acoustic emissions and other extremely small seismic events. Unlike previous calibration techniques, it does not require modeling of the wave propagation, sensor response, or signal conditioning. Rather, this technique calibrates the recording system as a whole and uses a ball impact as a reference source or empirical Green’s function. To correctly apply this technique, we develop mathematical expressions that link the seismic moment $M_{0}$ of internal seismic sources (i.e., earthquakes and acoustic emissions) to the impulse, or change in momentum $\\Delta p $, of externally applied seismic sources (i.e., meteor impacts or, in this case, ball impact). We find that, at low frequencies, moment and impulse are linked by a constant, which we call the force‐moment‐rate scale factor $C_{F\\dot{M}} = M_{0}/\\Delta p$. This constant is equal to twice the speed of sound in the material from which the seismic sources were generated. Next, we demonstrate the calibration technique on two different experimental rock mechanics facilities. The first example is a saw‐cut cylindrical granite sample that is loaded in a triaxial apparatus at 40 MPa confining pressure. The second example is a 2 m long fault cut in a granite sample and deformed in a large biaxial apparatus at lower stress levels. Using the empirical calibration technique, we are able to determine absolute source parameters including the seismic moment, corner frequency, stress drop, and radiated energy of these magnitude −2.5 to −7 seismic events.

  12. A case study of real-time monitoring of solid-state phase transformations in acoustically levitated particles using near infrared and Raman spectroscopy.

    PubMed

    Rehder, Sönke; Wu, Jian X; Laackmann, Julian; Moritz, Hans-Ulrich; Rantanen, Jukka; Rades, Thomas; Leopold, Claudia S

    2013-01-23

    The objective of this study was to monitor the amorphous-to-crystalline solid-state phase transformation kinetics of the model drug ibuprofen with spectroscopic methods during acoustic levitation. Chemical and physical information was obtained by real-time near infrared (NIRS) and Raman spectroscopy measurements. The recrystallisation kinetic parameters (overall recrystallisation rate constant β and the time needed to reach 50% of the equilibrated level t(50)), were determined using a multivariate curve resolution approach. The acoustic levitation device coupled with non-invasive spectroscopy enabled monitoring of the recrystallisation process of the difficult-to-handle (adhesive) amorphous sample. The application of multivariate curve resolution enabled isolation of the underlying pure spectra, which corresponded well with the reference spectra of amorphous and crystalline ibuprofen. The recrystallisation kinetic parameters were estimated from the recrystallisation profiles. While the empirical recrystallisation rate constant determined by NIR and Raman spectroscopy were comparable, the lag time for recrystallisation was significantly lower with Raman spectroscopy as compared to NIRS. This observation was explained by the high energy density of the Raman laser beam, which might have led to local heating effects of the sample and thus reduced the recrystallisation onset time. It was concluded that acoustic levitation with NIR and Raman spectroscopy combined with multivariate curve resolution allowed direct determination of the recrystallisation kinetics of amorphous drugs and thus is a promising technique for monitoring solid-state phase transformations of adhesive small-sized samples during the early phase of drug development. PMID:23069619

  13. Acoustic mapping velocimetry

    NASA Astrophysics Data System (ADS)

    Muste, M.; Baranya, S.; Tsubaki, R.; Kim, D.; Ho, H.; Tsai, H.; Law, D.

    2016-05-01

    Knowledge of sediment dynamics in rivers is of great importance for various practical purposes. Despite its high relevance in riverine environment processes, the monitoring of sediment rates remains a major and challenging task for both suspended and bed load estimation. While the measurement of suspended load is currently an active area of testing with nonintrusive technologies (optical and acoustic), bed load measurement does not mark a similar progress. This paper describes an innovative combination of measurement techniques and analysis protocols that establishes the proof-of-concept for a promising technique, labeled herein Acoustic Mapping Velocimetry (AMV). The technique estimates bed load rates in rivers developing bed forms using a nonintrusive measurements approach. The raw information for AMV is collected with acoustic multibeam technology that in turn provides maps of the bathymetry over longitudinal swaths. As long as the acoustic maps can be acquired relatively quickly and the repetition rate for the mapping is commensurate with the movement of the bed forms, successive acoustic maps capture the progression of the bed form movement. Two-dimensional velocity maps associated with the bed form migration are obtained by implementing algorithms typically used in particle image velocimetry to acoustic maps converted in gray-level images. Furthermore, use of the obtained acoustic and velocity maps in conjunction with analytical formulations (e.g., Exner equation) enables estimation of multidirectional bed load rates over the whole imaged area. This paper presents a validation study of the AMV technique using a set of laboratory experiments.

  14. Acoustic Monitoring of Beluga Whale Interactions with Cook Inlet Tidal Energy Project

    SciTech Connect

    Worthington, Monty

    2014-02-05

    Cook Inlet, Alaska is home to some of the greatest tidal energy resources in the U.S., as well as an endangered population of beluga whales (Delphinapterus leucas). Successfully permitting and operating a tidal power project in Cook Inlet requires a biological assessment of the potential and realized effects of the physical presence and sound footprint of tidal turbines on the distribution, relative abundance, and behavior of Cook Inlet beluga whales. ORPC Alaska, working with the Project Team—LGL Alaska Research Associates, University of Alaska Anchorage, TerraSond, and Greeneridge Science—undertook the following U.S. Department of Energy (DOE) study to characterize beluga whales in Cook Inlet – Acoustic Monitoring of Beluga Whale Interactions with the Cook Inlet Tidal Energy Project (Project). ORPC Alaska, LLC, is a wholly-owned subsidiary of Ocean Renewable Power Company, LLC, (collectively, ORPC). ORPC is a global leader in the development of hydrokinetic power systems and eco-conscious projects that harness the power of ocean and river currents to create clean, predictable renewable energy. ORPC is developing a tidal energy demonstration project in Cook Inlet at East Foreland where ORPC has a Federal Energy Regulatory Commission (FERC) preliminary permit (P-13821). The Project collected baseline data to characterize pre-deployment patterns of marine mammal distribution, relative abundance, and behavior in ORPC’s proposed deployment area at East Foreland. ORPC also completed work near Fire Island where ORPC held a FERC preliminary permit (P-12679) until March 6, 2013. Passive hydroacoustic devices (previously utilized with bowhead whales in the Beaufort Sea) were adapted for study of beluga whales to determine the relative abundance of beluga whale vocalizations within the proposed deployment areas. Hydroacoustic data collected during the Project were used to characterize the ambient acoustic environment of the project site pre-deployment to inform the

  15. Leak detection by acoustic emissions monitoring: An experimental investigation of the acoustic properties of leaks and the attenuation characteristics of soil

    NASA Astrophysics Data System (ADS)

    Kilpatrick, James F.; March, Patrick A.

    1994-05-01

    This study experimentally explored the conditions, equipment, and methodology necessary for the acoustic detection of small leaks of jet fuel (JP4) from underground storage tank (UST) systems. The study indicates that acoustic leak detection of very small leaks is feasible. In general, significant JP4 fuel leaks which occur across a 5 PSI (pounds per square inch) or greater pressure drop are acoustically active and can be detected with proper sensors and proper placement of sensors. The primary source of leak noise is turbulent flow through the leak orifice. At lower pressures, the leak flow becomes laminar, and the leak becomes virtually silent. With direct transducer contact on the pipe or tank wall and sufficient system pressure, leaks smaller than 0.1 GPH (gallons per hour) can be detected. Larger leaks can be detected through short distances in soil. However, sand, which is the most commonly used fill material for UST systems, provides significant acoustic attenuation. Consequently, waveguides must be used when monitoring distances exceeding about 1 foot of travel through sand. Sand acts to reduce background noise levels, providing an ideal environment for acoustic leak detection using sensors mounted directly on the pipe or tank wall.

  16. Sheet Resistance Low Dose Monitoring Using The Double Implant Technique

    NASA Astrophysics Data System (ADS)

    Smith, A. K.; Johnson, W. H.; Keenan, W. A.

    1986-06-01

    Sheet resistance has become an industry standard for monitoring high and medium dose ion implants. For low dose there are two sheet resistance techniques available, the direct implant technique and the double implant technique. Careful processing has extended the range of direct sheet resistance measurements down to doses of 2E11 ions/cm2. The double implant technique requires an initial implant to create an easily measured sheet resistance layer that serves as the test vehicle for the second implant. The dose of the second implant is measured by monitoring the change in the sheet resistance due to the implant damage created by the second implant into the first. This double implant technique is not limited to low dose nor to species that are electrically active in the substrate.

  17. Use of Acoustic Emission to Monitor Progressive Damage Accumulation in Kevlar (R) 49 Composites

    NASA Technical Reports Server (NTRS)

    Waller, Jess M.; Saulsberry, Regor L.; Andrade, Eduardo

    2009-01-01

    Acoustic emission (AE) data acquired during intermittent load hold tensile testing of epoxy impregnated Kevlar(Registeres TradeMark) 49 (K/Ep) composite strands were analyzed to monitor progressive damage during the approach to tensile failure. Insight into the progressive damage of K/Ep strands was gained by monitoring AE event rate and energy. Source location based on energy attenuation and arrival time data was used to discern between significant AE attributable to microstructural damage and spurious AE attributable to noise. One of the significant findings was the observation of increasing violation of the Kaiser effect (Felicity ratio < 1.0) with damage accumulation. The efficacy of three different intermittent load hold stress schedules that allowed the Felicity ratio to be determined analytically is discussed.

  18. Use of large-scale acoustic monitoring to assess anthropogenic pressures on Orthoptera communities.

    PubMed

    Penone, Caterina; Le Viol, Isabelle; Pellissier, Vincent; Julien, Jean-François; Bas, Yves; Kerbiriou, Christian

    2013-10-01

    Biodiversity monitoring at large spatial and temporal scales is greatly needed in the context of global changes. Although insects are a species-rich group and are important for ecosystem functioning, they have been largely neglected in conservation studies and policies, mainly due to technical and methodological constraints. Sound detection, a nondestructive method, is easily applied within a citizen-science framework and could be an interesting solution for insect monitoring. However, it has not yet been tested at a large scale. We assessed the value of a citizen-science program in which Orthoptera species (Tettigoniidae) were monitored acoustically along roads. We used Bayesian model-averaging analyses to test whether we could detect widely known patterns of anthropogenic effects on insects, such as the negative effects of urbanization or intensive agriculture on Orthoptera populations and communities. We also examined site-abundance correlations between years and estimated the biases in species detection to evaluate and improve the protocol. Urbanization and intensive agricultural landscapes negatively affected Orthoptera species richness, diversity, and abundance. This finding is consistent with results of previous studies of Orthoptera, vertebrates, carabids, and butterflies. The average mass of communities decreased as urbanization increased. The dispersal ability of communities increased as the percentage of agricultural land and, to a lesser extent, urban area increased. Despite changes in abundances over time, we found significant correlations between yearly abundances. We identified biases linked to the protocol (e.g., car speed or temperature) that can be accounted for ease in analyses. We argue that acoustic monitoring of Orthoptera along roads offers several advantages for assessing Orthoptera biodiversity at large spatial and temporal extents, particularly in a citizen science framework.

  19. Use of large-scale acoustic monitoring to assess anthropogenic pressures on Orthoptera communities.

    PubMed

    Penone, Caterina; Le Viol, Isabelle; Pellissier, Vincent; Julien, Jean-François; Bas, Yves; Kerbiriou, Christian

    2013-10-01

    Biodiversity monitoring at large spatial and temporal scales is greatly needed in the context of global changes. Although insects are a species-rich group and are important for ecosystem functioning, they have been largely neglected in conservation studies and policies, mainly due to technical and methodological constraints. Sound detection, a nondestructive method, is easily applied within a citizen-science framework and could be an interesting solution for insect monitoring. However, it has not yet been tested at a large scale. We assessed the value of a citizen-science program in which Orthoptera species (Tettigoniidae) were monitored acoustically along roads. We used Bayesian model-averaging analyses to test whether we could detect widely known patterns of anthropogenic effects on insects, such as the negative effects of urbanization or intensive agriculture on Orthoptera populations and communities. We also examined site-abundance correlations between years and estimated the biases in species detection to evaluate and improve the protocol. Urbanization and intensive agricultural landscapes negatively affected Orthoptera species richness, diversity, and abundance. This finding is consistent with results of previous studies of Orthoptera, vertebrates, carabids, and butterflies. The average mass of communities decreased as urbanization increased. The dispersal ability of communities increased as the percentage of agricultural land and, to a lesser extent, urban area increased. Despite changes in abundances over time, we found significant correlations between yearly abundances. We identified biases linked to the protocol (e.g., car speed or temperature) that can be accounted for ease in analyses. We argue that acoustic monitoring of Orthoptera along roads offers several advantages for assessing Orthoptera biodiversity at large spatial and temporal extents, particularly in a citizen science framework. PMID:23692213

  20. Optimal Suturing Technique and Number of Sutures for Surgical Implantation of Acoustic Transmitters in Juvenile Salmonids

    SciTech Connect

    Deters, Katherine A.; Brown, Richard S.; Boyd, James W.; Eppard, M. B.; Seaburg, Adam

    2012-01-02

    The size reduction of acoustic transmitters has led to a reduction in the length of incision needed to implant a transmitter. Smaller suture knot profiles and fewer sutures may be adequate for closing an incision used to surgically implant an acoustic microtransmitter. As a result, faster surgery times and reduced tissue trauma could lead to increased survival and decreased infection for implanted fish. The objective of this study was to assess the effects of five suturing techniques on mortality, tag and suture retention, incision openness, ulceration, and redness in juvenile Chinook salmon Oncorhynchus tshawytscha implanted with acoustic microtransmitters. Suturing was performed by three surgeons, and study fish were held at two water temperatures (12°C and 17°C). Mortality was low and tag retention was high for all treatments on all examination days (7, 14, 21, and 28 days post-surgery). Because there was surgeon variation in suture retention among treatments, further analyses included only the one surgeon who received feedback training in all suturing techniques. Incision openness and tissue redness did not differ among treatments. The only difference observed among treatments was in tissue ulceration. Incisions closed with a horizontal mattress pattern had more ulceration than other treatments among fish held for 28 days at 17°C. Results from this study suggest that one simple interrupted 1 × 1 × 1 × 1 suture is adequate for closing incisions on fish under most circumstances. However, in dynamic environments, two simple interrupted 1 × 1 × 1 × 1 sutures should provide adequate incision closure. Reducing bias in survival and behavior tagging studies is important when making comparisons to the migrating salmon population. Therefore, by minimizing the effects of tagging on juvenile salmon (reduced tissue trauma and reduced surgery time), researchers can more accurately estimate survival and behavior.

  1. Acoustic puncture assist device versus loss of resistance technique for epidural space identification

    PubMed Central

    Mittal, Amit Kumar; Goel, Nitesh; Chowdhury, Itee; Shah, Shagun Bhatia; Singh, Brijesh Pratap; Jakhar, Pradeep

    2016-01-01

    Background and Aims: The conventional techniques of epidural space (EDS) identification based on loss of resistance (LOR) have a higher chance of complications, patchy analgesia and epidural failure, which can be minimised by objective confirmation of space before catheter placement. Acoustic puncture assist device (APAD) technique objectively confirms EDS, thus enhancing success, with lesser complications. This study was planned with the objective to evaluate the APAD technique and compare it to LOR technique for EDS identification and its correlation with ultrasound guided EDS depth. Methods: In this prospective study, the lumbar vertebral spaces were scanned by the ultrasound for measuring depth of the EDS and later correlated with procedural depth measured by either of the technique (APAD or LOR). The data were subjected to descriptive statistics; the concordance correlation coefficient and Bland-Altman analysis with 95% confidence limits. Results: Acoustic dip in pitch and descent in pressure tracing on EDS localisation was observed among the patients of APAD group. Analysis of concordance correlation between the ultrasonography (USG) depth and APAD or LOR depth was significant (r ≥ 0.97 in both groups). Bland-Altman analysis revealed a mean difference of 0.171cm in group APAD and 0.154 cm in group LOR. The 95% limits of agreement for the difference between the two measurements were − 0.569 and 0.226 cm in APAD and − 0.530 to 0.222 cm in LOR group. Conclusion: We found APAD to be a precise tool for objective localisation of the EDS, co-relating well with the pre-procedural USG depth of EDS. PMID:27212720

  2. Passive acoustic monitoring of coastally associated Hawaiian spinner dolphins, Stenella longirostris, ground-truthed through visual surveys.

    PubMed

    Heenehan, Heather L; Tyne, Julian A; Bejder, Lars; Van Parijs, Sofie M; Johnston, David W

    2016-07-01

    Effective decision making to protect coastally associated dolphins relies on monitoring the presence of animals in areas that are critical to their survival. Hawaiian spinner dolphins forage at night and rest during the day in shallow bays. Due to their predictable presence, they are targeted by dolphin-tourism. In this study, comparisons of presence were made between passive acoustic monitoring (PAM) and vessel-based visual surveys in Hawaiian spinner dolphin resting bays. DSG-Ocean passive acoustic recording devices were deployed in four bays along the Kona Coast of Hawai'i Island between January 8, 2011 and August 30, 2012. The devices sampled at 80 kHz, making 30-s recordings every four minutes. Overall, dolphins were acoustically detected on 37.1% to 89.6% of recording days depending on the bay. Vessel-based visual surveys overlapped with the PAM surveys on 202 days across the four bays. No significant differences were found between visual and acoustic detections suggesting acoustic surveys can be used as a proxy for visual surveys. Given the need to monitor dolphin presence across sites, PAM is the most suitable and efficient tool for monitoring long-term presence/absence. Concomitant photo-identification surveys are necessary to address changes in abundance over time. PMID:27475147

  3. A non-invasive acoustic and vibration analysis technique for evaluation of hip joint conditions.

    PubMed

    Glaser, Diana; Komistek, Richard D; Cates, Harold E; Mahfouz, Mohamed R

    2010-02-10

    The performance evaluation of THA outcome is difficult and surgeons often use invasive methods to investigate effectiveness. A non-invasive acoustic and vibration analysis technique has recently been developed for more-in-depth evaluation of in vivo hip conditions. Gait kinematics, corresponding vibration and sound measurement of five THA subjects were analyzed post-operatively using video-fluoroscopy, sound and accelerometer measurements while walking on a treadmill. The sound sensor and a pair of tri-axial accelerometers, externally attached to the pelvic and femoral bone prominences, detected frequencies that are propagated through the femoral head and acetabular cup interactions. A data acquisition system was used to amplify the signal and filter out noise generated by undesired frequencies. In vivo kinematics and femoral head sliding quantified using video fluoroscopy were correlated to the sound and acceleration measurements. Distinct variations between the different subjects were identified. A correlation of sound and acceleration impulses with separation has been achieved. Although, in vivo sounds are quite variable in nature and all correlated well with the visual images. This is the first study to document and correlate visual and audible effects of THA under in-vivo conditions. This study has shown that the development of the acoustic and vibration technique provides a practical method and generates new possibilities for a better understanding of THA performance.

  4. A non-invasive acoustic and vibration analysis technique for evaluation of hip joint conditions.

    PubMed

    Glaser, Diana; Komistek, Richard D; Cates, Harold E; Mahfouz, Mohamed R

    2010-02-10

    The performance evaluation of THA outcome is difficult and surgeons often use invasive methods to investigate effectiveness. A non-invasive acoustic and vibration analysis technique has recently been developed for more-in-depth evaluation of in vivo hip conditions. Gait kinematics, corresponding vibration and sound measurement of five THA subjects were analyzed post-operatively using video-fluoroscopy, sound and accelerometer measurements while walking on a treadmill. The sound sensor and a pair of tri-axial accelerometers, externally attached to the pelvic and femoral bone prominences, detected frequencies that are propagated through the femoral head and acetabular cup interactions. A data acquisition system was used to amplify the signal and filter out noise generated by undesired frequencies. In vivo kinematics and femoral head sliding quantified using video fluoroscopy were correlated to the sound and acceleration measurements. Distinct variations between the different subjects were identified. A correlation of sound and acceleration impulses with separation has been achieved. Although, in vivo sounds are quite variable in nature and all correlated well with the visual images. This is the first study to document and correlate visual and audible effects of THA under in-vivo conditions. This study has shown that the development of the acoustic and vibration technique provides a practical method and generates new possibilities for a better understanding of THA performance. PMID:19931084

  5. Monitoring techniques for the manufacture of tapered optical fibers.

    PubMed

    Mullaney, Kevin; Correia, Ricardo; Staines, Stephen E; James, Stephen W; Tatam, Ralph P

    2015-10-01

    The use of a range of optical techniques to monitor the process of fabricating optical fiber tapers is investigated. Thermal imaging was used to optimize the alignment of the optical system; the transmission spectrum of the fiber was monitored to confirm that the tapers had the required optical properties and the strain induced in the fiber during tapering was monitored using in-line optical fiber Bragg gratings. Tapers were fabricated with diameters down to 5 μm and with waist lengths of 20 mm using single-mode SMF-28 fiber. PMID:26479631

  6. A passive acoustic device for real-time monitoring of the efficacy of shockwave lithotripsy treatment.

    PubMed

    Leighton, T G; Fedele, F; Coleman, A J; McCarthy, C; Ryves, S; Hurrell, A M; De Stefano, A; White, P R

    2008-10-01

    Extracorporeal shockwave lithotripsy (ESWL) is the preferred modality for the treatment of renal and ureteric stone disease. Currently X-ray or ultrasound B-scan imaging are used to locate the stone and to check that it remains targeted at the focus of the lithotripter during treatment. Neither imaging modality is particularly effective in allowing the efficacy of treatment to be judged during the treatment session. A new device is described that, when placed on the patient's skin, can passively monitor the acoustic signals that propagate through the body after each lithotripter shock, and which can provide useful information on the effectiveness of targeting. These acoustic time histories are analyzed in real time to extract the two main characteristic peak amplitudes (m(1) and m(2)) and the time between these peaks (t(c)). A set of rules based on the acoustic parameters was developed during a clinical study in which a complete set of acoustic and clinical data was obtained for 30 of the 118 subjects recruited. The rules, which complied with earlier computational fluid dynamics (CFD) modeling and in vitro tests, allow each shock to be classified as "effective" or "ineffective." These clinically-derived rules were then applied in a second clinical study in which complete datasets were obtained for 49 of the 85 subjects recruited. This second clinical study demonstrated almost perfect agreement (kappa = 0.94) between the number of successful treatments, defined as >50% fragmentation as determined by X-ray at the follow-up appointment, and a device-derived global treatment score, TS(0), a figure derived from the total number of effective shocks in any treatment. The acoustic system is shown to provide a test of the success of the treatment that has a sensitivity of 91.7% and a specificity of 100%. In addition to the predictive capability, the device provides valuable real-time feedback to the lithotripter operator by indicating the effectiveness of each shock, plus

  7. Energy monitoring and analysis during deformation of bedded-sandstone: use of acoustic emission.

    PubMed

    Wasantha, P L P; Ranjith, P G; Shao, S S

    2014-01-01

    This paper investigates the mechanical behaviour and energy releasing characteristics of bedded-sandstone with bedding layers in different orientations, under uniaxial compression. Cylindrical sandstone specimens (54 mm diameter and 108 mm height) with bedding layers inclined at angles of 10°, 20°, 35°, 55°, and 83° to the minor principal stress direction, were produced to perform a series of Uniaxial Compressive Strength (UCS) tests. One of the two identical sample sets was fully-saturated with water before testing and the other set was tested under dry conditions. An acoustic emission system was employed in all the testing to monitor the acoustic energy release during the whole deformation process of specimens. From the test results, the critical joint orientation was observed as 55° for both dry and saturated samples and the peak-strength losses due to water were 15.56%, 20.06%, 13.5%, 13.2%, and 13.52% for the bedding orientations 10°, 20°, 35°, 55°, and 83°, respectively. The failure mechanisms for the specimens with bedding layers in 10°, 20° orientations showed splitting type failure, while the specimens with bedding layers in 55°, 83° orientations were failed by sliding along a weaker bedding layer. The failure mechanism for the specimens with bedding layers in 35° orientation showed a mixed failure mode of both splitting and sliding types. Analysis of the acoustic energy, captured from the acoustic emission detection system, revealed that the acoustic energy release is considerably higher in dry specimens than that of the saturated specimens at any bedding orientation. In addition, higher energy release was observed for specimens with bedding layers oriented in shallow angles (which were undergoing splitting type failures), whereas specimens with steeply oriented bedding layers (which were undergoing sliding type failures) showed a comparatively less energy release under both dry and saturated conditions. Moreover, a considerable amount of

  8. Energy monitoring and analysis during deformation of bedded-sandstone: use of acoustic emission.

    PubMed

    Wasantha, P L P; Ranjith, P G; Shao, S S

    2014-01-01

    This paper investigates the mechanical behaviour and energy releasing characteristics of bedded-sandstone with bedding layers in different orientations, under uniaxial compression. Cylindrical sandstone specimens (54 mm diameter and 108 mm height) with bedding layers inclined at angles of 10°, 20°, 35°, 55°, and 83° to the minor principal stress direction, were produced to perform a series of Uniaxial Compressive Strength (UCS) tests. One of the two identical sample sets was fully-saturated with water before testing and the other set was tested under dry conditions. An acoustic emission system was employed in all the testing to monitor the acoustic energy release during the whole deformation process of specimens. From the test results, the critical joint orientation was observed as 55° for both dry and saturated samples and the peak-strength losses due to water were 15.56%, 20.06%, 13.5%, 13.2%, and 13.52% for the bedding orientations 10°, 20°, 35°, 55°, and 83°, respectively. The failure mechanisms for the specimens with bedding layers in 10°, 20° orientations showed splitting type failure, while the specimens with bedding layers in 55°, 83° orientations were failed by sliding along a weaker bedding layer. The failure mechanism for the specimens with bedding layers in 35° orientation showed a mixed failure mode of both splitting and sliding types. Analysis of the acoustic energy, captured from the acoustic emission detection system, revealed that the acoustic energy release is considerably higher in dry specimens than that of the saturated specimens at any bedding orientation. In addition, higher energy release was observed for specimens with bedding layers oriented in shallow angles (which were undergoing splitting type failures), whereas specimens with steeply oriented bedding layers (which were undergoing sliding type failures) showed a comparatively less energy release under both dry and saturated conditions. Moreover, a considerable amount of

  9. Damage Modes Recognition and Hilbert-Huang Transform Analyses of CFRP Laminates Utilizing Acoustic Emission Technique

    NASA Astrophysics Data System (ADS)

    WenQin, Han; Ying, Luo; AiJun, Gu; Yuan, Fuh-Gwo

    2016-04-01

    Discrimination of acoustic emission (AE) signals related to different damage modes is of great importance in carbon fiber-reinforced plastic (CFRP) composite materials. To gain a deeper understanding of the initiation, growth and evolution of the different types of damage, four types of specimens for different lay-ups and orientations and three types of specimens for interlaminar toughness tests are subjected to tensile test along with acoustic emission monitoring. AE signals have been collected and post-processed, the statistical results show that the peak frequency of AE signal can distinguish various damage modes effectively. After a AE signal were decomposed by Empirical Mode Decomposition (EMD) method, it may separate and extract all damage modes included in this AE signal apart from damage mode corresponding to the peak frequency. Hilbert-Huang Transform (HHT) of AE signals can clearly illustrate the frequency distribution of Intrinsic Mode Functions (IMF) components in time-scale in different damage stages, and can calculate accurate instantaneous frequency for damage modes recognition to help understanding the damage process.

  10. Evaluation of change detection techniques for monitoring coastal zone environments

    NASA Technical Reports Server (NTRS)

    Weismiller, R. A.; Kristof, S. J.; Scholz, D. K.; Anuta, P. E.; Momin, S. M.

    1977-01-01

    Development of satisfactory techniques for detecting change in coastal zone environments is required before operational monitoring procedures can be established. In an effort to meet this need a study was directed toward developing and evaluating different types of change detection techniques, based upon computer aided analysis of LANDSAT multispectral scanner (MSS) data, to monitor these environments. The Matagorda Bay estuarine system along the Texas coast was selected as the study area. Four change detection techniques were designed and implemented for evaluation: (1) post classification comparison change detection, (2) delta data change detection, (3) spectral/temporal change classification, and (4) layered spectral/temporal change classification. Each of the four techniques was used to analyze a LANDSAT MSS temporal data set to detect areas of change of the Matagorda Bay region.

  11. Assessment of ground-based monitoring techniques applied to landslide investigations

    NASA Astrophysics Data System (ADS)

    Uhlemann, S.; Smith, A.; Chambers, J.; Dixon, N.; Dijkstra, T.; Haslam, E.; Meldrum, P.; Merritt, A.; Gunn, D.; Mackay, J.

    2016-01-01

    A landslide complex in the Whitby Mudstone Formation at Hollin Hill, North Yorkshire, UK is periodically re-activated in response to rainfall-induced pore-water pressure fluctuations. This paper compares long-term measurements (i.e., 2009-2014) obtained from a combination of monitoring techniques that have been employed together for the first time on an active landslide. The results highlight the relative performance of the different techniques, and can provide guidance for researchers and practitioners for selecting and installing appropriate monitoring techniques to assess unstable slopes. Particular attention is given to the spatial and temporal resolutions offered by the different approaches that include: Real Time Kinematic-GPS (RTK-GPS) monitoring of a ground surface marker array, conventional inclinometers, Shape Acceleration Arrays (SAA), tilt meters, active waveguides with Acoustic Emission (AE) monitoring, and piezometers. High spatial resolution information has allowed locating areas of stability and instability across a large slope. This has enabled identification of areas where further monitoring efforts should be focused. High temporal resolution information allowed the capture of 'S'-shaped slope displacement-time behaviour (i.e. phases of slope acceleration, deceleration and stability) in response to elevations in pore-water pressures. This study shows that a well-balanced suite of monitoring techniques that provides high temporal and spatial resolutions on both measurement and slope scale is necessary to fully understand failure and movement mechanisms of slopes. In the case of the Hollin Hill landslide it enabled detailed interpretation of the geomorphological processes governing landslide activity. It highlights the benefit of regularly surveying a network of GPS markers to determine areas for installation of movement monitoring techniques that offer higher resolution both temporally and spatially. The small sensitivity of tilt meter measurements

  12. A multi path, weather independent avalanche monitoring tool using distributed acoustic fiber optic sensing

    NASA Astrophysics Data System (ADS)

    Prokop, Alexander; Wirbel, Anna

    2013-04-01

    Information on avalanche activity is a paramount parameter in avalanche forecasting. When avalanches are released spontaneously, the risk of avalanches is very high. Triggering avalanches by artificial means, such as explosives launched from helicopter or avalanche towers, can also give information on the stability of the snow pack. Hence, monitoring of avalanches released naturally or artificially, is an important quantity in avalanche forecasting. This information is also needed when deciding whether to close or not endangered ski runs, roads or railway lines. So far monitoring systems lack certain benefits. Either they monitor only large avalanches, can only be used for single avalanche tracks or are weather/sight dependant. Therefore a new tool for avalanche- monitoring, a distributed fiber optic system, is for the first time installed and adapted for the purpose of monitoring snow avalanche activity. The method is based on an optical time domain reflectometer (OTDR) system, which dates back to the 1970`s and detects seismic vibrations and acoustic signals on a fiber optic cable that can have a length of up to 30 km. An appropriate test slope for this configuration has been found in the ski area of "Lech am Arlberg". In this work a detailed description of the theoretical background, the system implementation, the field installation, realization of tests and an investigation of the recorded data is presented. We conducted 100 tests and triggered 41 avalanches so far with a runout distances ranging from a few meters to approximately 250 meters, all of which were detected by the system, as well as the 59 not successful attempts of artificial triggering. Moreover we measured properly if critical infrastructure (in our case a ski run) was reached by the avalanches or not. The spatial distributed sensing approach allowed us to relate the amplitude and spectral content of the signals to avalanche size, avalanche speed and snow properties of the avalanches. In

  13. [Comparative study of two techniques of ciclosporine monitoring].

    PubMed

    Charfi, Rim; El Jebari, Hanène; Gaïes, Emna; Charfi, Ons; Jebabli, Nadia; Thouraya, Riahi; Ben Messaouda, Mhamed; Lakhal, Mohamed; Klouz, Anis; Salouage, Issam; Trabelsi, Sameh

    2015-01-01

    Ciclosporine (CsA) is an immunosuppressant drug used in bone marrow transplantation in order to extend allograft survival. Despite its efficiency, CsA can expose to therapeutic failure or to toxicity because of underdosing or overdosage. So, many techniques of monitoring CsA in blood were used, the referance one is the chromatographic technique then, the automated techniques: fluorescence polarization immunoassay (FPIA) and chimiluminescent microparticle immunoassay (CMIA). In this study, we aimed to compare the results of CsA concentrations measured by the two automised techniques. Statistical studies showed that the two techniques were repeatable and reproductible. Results obtained by FPIA were slightly higher than those obtained by CMIA but without a significative difference. In conclusion, FPIA technique could be used to measure CsA blood concentration in replacement of CMIA in case of technical problems.

  14. Acoustic emission and guided ultrasonic waves for detection and continuous monitoring of cracks in light water reactor components

    SciTech Connect

    Meyer, R. M.; Coble, J.; Ramuhalli, P.; Watson, B.; Cumblidge, S. E.; Doctor, S. R.; Bond, L. J.

    2012-07-01

    Acoustic emission (AE) and guided ultrasonic waves (GUW) are considered for continuous monitoring and detection of cracks in Light Water Reactor (LWR) components. In this effort, both techniques are applied to the detection and monitoring of fatigue crack growth in a full scale pipe component. AE results indicated crack initiation and rapid growth in the pipe, and significant GUW responses were observed in response to the growth of the fatigue crack. After initiation, the crack growth was detectable with AE for approximately 20,000 cycles. Signals associated with initiation and rapid growth were distinguished based on total rate of activity and differences observed in the centroid frequency of hits. An intermediate stage between initiation and rapid growth was associated with significant energy emissions, though few hits. GUW exhibit a nearly monotonic trend with crack length with an exception of measurements obtained at crack lengths of 41 mm and 46 mm. Coupling variability and shadowing by the electro-discharge machining (EDM) starter notch set the lower limit of detectability. (authors)

  15. Interim Report on Concrete Degradation Mechanisms and Online Monitoring Techniques

    SciTech Connect

    Mahadevan, Sankaran; Agarwal, Vivek; Neal, Kyle; Kosson, David; Adams, Douglas

    2014-09-01

    The existing nuclear power plants in the United States have initial operating licenses of 40 years, though most of these plants have applied for and received license extensions. As plant structures, systems, and components age, their useful life—considering both structural integrity and performance—is reduced as a result of deterioration of the materials. The research on online monitoring of concrete structures conducted under the Advanced Instrumentation, Information, and Control Systems Technologies Pathway of the Light Water Reactor Sustainability Program at Idaho National Laboratory will develop and demonstrate concrete structures health monitoring capabilities. Assessment and management of aging concrete structures in nuclear plants require a more systematic approach than simple reliance on existing code margins of safety. Therefore, structural health monitoring is required to produce actionable information regarding structural integrity that supports operational and maintenance decisions. Through this research project, several national laboratories and Vanderbilt University propose to develop a framework of research activities for the health monitoring of nuclear power plant concrete structures that includes the integration of four elements—damage modeling, monitoring, data analytics, and uncertainty quantification. This report briefly discusses available techniques and ongoing challenges in each of the four elements of the proposed framework with emphasis on degradation mechanisms and online monitoring techniques.

  16. Monitoring the volume and lateral spread of disposed sediments by acoustic methods, Oslo Harbor, Norway.

    PubMed

    Lepland, Aivo; Bøe, Reidulv; Lepland, Aave; Totland, Oddbjørn

    2009-08-01

    Acoustic equipment, including interferometric sonar and parametric sub-bottom profiler, have been used to determine the volume and lateral spread of dredged sediments disposed in the natural submarine depression in the Bekkelag Basin, inner Oslofjord since the beginning of the Oslo Harbor remediation project in 2006. This natural depression is used as a subaqueous confined disposal facility (CDF). Calculation of the volume of disposed sediments in the CDF is based on elevation change, derived from two high-resolution bathymetric datasets obtained in 2004, i.e. before the onset of the remediation project, and in April 2008. Seismic profiles across the CDF have been used to estimate the settlement of the original seabed, caused by loading-induced dewatering and compaction of the seabed sediments under the disposed masses. Detailed bathymetry and backscatter data demonstrate the lateral spread of disposed sediments within a well-confined area covering ca. 195,000m(2). The sea bottom within this area is distinctly softer than the surrounding seabed as shown by very low acoustic backscatter amplitude, signifying a very loose surface character of the disposed sediments. The thickness of the disposed sediments reaches 6m the deepest part of the original depression. The volume calculation of the disposed sediments in the CDF, based solely on bathymetry data, gives a value of ca. 310,000-320,000m(3). Settlement of the original seabed as a result of loading has been estimated to be 30cm at 5m thickness of the disposed sediments. Under the condition that the settlement rate is linearly correlated to the thickness of disposed sediments, the settlement corrected volume of disposed sediments is ca. 330,000-340,000m(3). Presented results demonstrate high accuracy and good reproducibility of acoustic seafloor data, and indicate a great potential of such methods as monitoring tools in environmental projects that involve dredging and subaqueous disposal.

  17. Controlled Ultrasound-Induced Blood-Brain Barrier Disruption Using Passive Acoustic Emissions Monitoring

    PubMed Central

    Arvanitis, Costas D.; Livingstone, Margaret S.; Vykhodtseva, Natalia; McDannold, Nathan

    2012-01-01

    The ability of ultrasonically-induced oscillations of circulating microbubbles to permeabilize vascular barriers such as the blood-brain barrier (BBB) holds great promise for noninvasive targeted drug delivery. A major issue has been a lack of control over the procedure to ensure both safe and effective treatment. Here, we evaluated the use of passively-recorded acoustic emissions as a means to achieve this control. An acoustic emissions monitoring system was constructed and integrated into a clinical transcranial MRI-guided focused ultrasound system. Recordings were analyzed using a spectroscopic method that isolates the acoustic emissions caused by the microbubbles during sonication. This analysis characterized and quantified harmonic oscillations that occur when the BBB is disrupted, and broadband emissions that occur when tissue damage occurs. After validating the system's performance in pilot studies that explored a wide range of exposure levels, the measurements were used to control the ultrasound exposure level during transcranial sonications at 104 volumes over 22 weekly sessions in four macaques. We found that increasing the exposure level until a large harmonic emissions signal was observed was an effective means to ensure BBB disruption without broadband emissions. We had a success rate of 96% in inducing BBB disruption as measured by in contrast-enhanced MRI, and we detected broadband emissions in less than 0.2% of the applied bursts. The magnitude of the harmonic emissions signals was significantly (P<0.001) larger for sonications where BBB disruption was detected, and it correlated with BBB permeabilization as indicated by the magnitude of the MRI signal enhancement after MRI contrast administration (R2 = 0.78). Overall, the results indicate that harmonic emissions can be a used to control focused ultrasound-induced BBB disruption. These results are promising for clinical translation of this technology. PMID:23029240

  18. Optimization of real-time acoustical and mechanical monitoring of high intensity focused ultrasound (HIFU) treatment using harmonic motion imaging for high focused ultrasound (HMIFU).

    PubMed

    Hou, Gary Y; Marquet, Fabrice; Wang, Shutao; Konofagou, Elisa E

    2013-01-01

    Harmonic Motion Imaging (HMI) for Focused Ultrasound (HMIFU) is a recently developed high-intensity focused ultrasound (HIFU) treatment monitoring method with feasibilities demonstrated in silica, in vitro and in vivo. Its principle is based on emission of an Amplitude-modulated therapeutic ultrasound beam utilizing a therapeutic transducer to induce an oscillatory radiation force while tracking the focal tissue mechanical response during the HIFU treatment using a confocally-aligned diagnostic transducer. In order to translate towards the clinical implementation of HMIFU, a complete assessment study is required in order to investigate the optimal radiation force threshold for reliable monitoring the local tissue mechanical property changes, i.e., the estimation HMIFU displacement under thermal, acoustical, and mechanical effects within focal medium (i.e., boiling, cavitation, and nonlinearity) using biological specimen. In this study, HMIFU technique is applied on HIFU treatment monitoring on freshly excised ex vivo canine liver specimens. In order to perform the multi-characteristic assessment, the diagnostic transducer was operated as either a pulse-echo imager or Passive Cavitation Detector (PCD) to assess the acoustic and mechanical response, while a bare-wire thermocouple was used to monitor the focal temperature change. As the acoustic power of HIFU treatment was ranged from 2.3 to 11.4 W, robust HMI displacement was observed across the entire range. Moreover, an optimized range for high quality displacement monitoring was found to be between 3.6 to 5.2W, where displacement showed an increase followed by significant decrease, indicating a stiffening of focal medium due to thermal lesion formation, while the correlation coefficient was maintained above 0.95.

  19. Optimization of real-time acoustical and mechanical monitoring of high intensity focused ultrasound (HIFU) treatment using harmonic motion imaging for high focused ultrasound (HMIFU).

    PubMed

    Hou, Gary Y; Marquet, Fabrice; Wang, Shutao; Konofagou, Elisa E

    2013-01-01

    Harmonic Motion Imaging (HMI) for Focused Ultrasound (HMIFU) is a recently developed high-intensity focused ultrasound (HIFU) treatment monitoring method with feasibilities demonstrated in silica, in vitro and in vivo. Its principle is based on emission of an Amplitude-modulated therapeutic ultrasound beam utilizing a therapeutic transducer to induce an oscillatory radiation force while tracking the focal tissue mechanical response during the HIFU treatment using a confocally-aligned diagnostic transducer. In order to translate towards the clinical implementation of HMIFU, a complete assessment study is required in order to investigate the optimal radiation force threshold for reliable monitoring the local tissue mechanical property changes, i.e., the estimation HMIFU displacement under thermal, acoustical, and mechanical effects within focal medium (i.e., boiling, cavitation, and nonlinearity) using biological specimen. In this study, HMIFU technique is applied on HIFU treatment monitoring on freshly excised ex vivo canine liver specimens. In order to perform the multi-characteristic assessment, the diagnostic transducer was operated as either a pulse-echo imager or Passive Cavitation Detector (PCD) to assess the acoustic and mechanical response, while a bare-wire thermocouple was used to monitor the focal temperature change. As the acoustic power of HIFU treatment was ranged from 2.3 to 11.4 W, robust HMI displacement was observed across the entire range. Moreover, an optimized range for high quality displacement monitoring was found to be between 3.6 to 5.2W, where displacement showed an increase followed by significant decrease, indicating a stiffening of focal medium due to thermal lesion formation, while the correlation coefficient was maintained above 0.95. PMID:24111176

  20. Process tool monitoring and matching using interferometry technique

    NASA Astrophysics Data System (ADS)

    Anberg, Doug; Owen, David M.; Mileham, Jeffrey; Lee, Byoung-Ho; Bouche, Eric

    2016-03-01

    The semiconductor industry makes dramatic device technology changes over short time periods. As the semiconductor industry advances towards to the 10 nm device node, more precise management and control of processing tools has become a significant manufacturing challenge. Some processes require multiple tool sets and some tools have multiple chambers for mass production. Tool and chamber matching has become a critical consideration for meeting today's manufacturing requirements. Additionally, process tools and chamber conditions have to be monitored to ensure uniform process performance across the tool and chamber fleet. There are many parameters for managing and monitoring tools and chambers. Particle defect monitoring is a well-known and established example where defect inspection tools can directly detect particles on the wafer surface. However, leading edge processes are driving the need to also monitor invisible defects, i.e. stress, contamination, etc., because some device failures cannot be directly correlated with traditional visualized defect maps or other known sources. Some failure maps show the same signatures as stress or contamination maps, which implies correlation to device performance or yield. In this paper we present process tool monitoring and matching using an interferometry technique. There are many types of interferometry techniques used for various process monitoring applications. We use a Coherent Gradient Sensing (CGS) interferometer which is self-referencing and enables high throughput measurements. Using this technique, we can quickly measure the topography of an entire wafer surface and obtain stress and displacement data from the topography measurement. For improved tool and chamber matching and reduced device failure, wafer stress measurements can be implemented as a regular tool or chamber monitoring test for either unpatterned or patterned wafers as a good criteria for improved process stability.

  1. Passive wireless surface acoustic wave sensors for monitoring sequestration sites CO2 emission

    SciTech Connect

    Wang, Yizhong; Chyu, Minking; Wang, Qing-Ming

    2013-02-14

    University of Pittsburgh’s Transducer lab has teamed with the U.S. Department of Energy’s National Energy Technology Laboratory (DOE NETL) to conduct a comprehensive study to develop/evaluate low-cost, efficient CO2 measuring technologies for geological sequestration sites leakage monitoring. A passive wireless CO2 sensing system based on surface acoustic wave technology and carbon nanotube nanocomposite was developed. Surface acoustic wave device was studied to determine the optimum parameters. Delay line structure was adopted as basic sensor structure. CNT polymer nanocomposite was fabricated and tested under different temperature and strain condition for natural environment impact evaluation. Nanocomposite resistance increased for 5 times under pure strain, while the temperature dependence of resistance for CNT solely was -1375ppm/°C. The overall effect of temperature on nanocomposite resistance was -1000ppm/°C. The gas response of the nanocomposite was about 10% resistance increase under pure CO2 . The sensor frequency change was around 300ppm for pure CO2 . With paralyne packaging, the sensor frequency change from relative humidity of 0% to 100% at room temperature decreased from over 1000ppm to less than 100ppm. The lowest detection limit of the sensor is 1% gas concentration, with 36ppm frequency change. Wireless module was tested and showed over one foot transmission distance at preferred parallel orientation.

  2. Stress-Induced Fracturing of Reservoir Rocks: Acoustic Monitoring and μCT Image Analysis

    NASA Astrophysics Data System (ADS)

    Pradhan, Srutarshi; Stroisz, Anna M.; Fjær, Erling; Stenebråten, Jørn F.; Lund, Hans K.; Sønstebø, Eyvind F.

    2015-11-01

    Stress-induced fracturing in reservoir rocks is an important issue for the petroleum industry. While productivity can be enhanced by a controlled fracturing operation, it can trigger borehole instability problems by reactivating existing fractures/faults in a reservoir. However, safe fracturing can improve the quality of operations during CO2 storage, geothermal installation and gas production at and from the reservoir rocks. Therefore, understanding the fracturing behavior of different types of reservoir rocks is a basic need for planning field operations toward these activities. In our study, stress-induced fracturing of rock samples has been monitored by acoustic emission (AE) and post-experiment computer tomography (CT) scans. We have used hollow cylinder cores of sandstones and chalks, which are representatives of reservoir rocks. The fracture-triggering stress has been measured for different rocks and compared with theoretical estimates. The population of AE events shows the location of main fracture arms which is in a good agreement with post-test CT image analysis, and the fracture patterns inside the samples are visualized through 3D image reconstructions. The amplitudes and energies of acoustic events clearly indicate initiation and propagation of the main fractures. Time evolution of the radial strain measured in the fracturing tests will later be compared to model predictions of fracture size.

  3. Monitoring asphalt pavement damages using remote sensing techniques

    NASA Astrophysics Data System (ADS)

    Mettas, Christodoulos; Themistocleous, Kyriacos; Neocleous, Kyriacos; Christofe, Andreas; Pilakoutas, Kypros; Hadjimitsis, Diofantos

    2015-06-01

    One of the main issues in the maintenance plans of road agencies or governmental organizations is the early detection of damaged asphalt pavements. The development of a smart and non-destructive systematic technique for monitoring damaged asphalt pavements is considered a main priority to fill this gap. During the 1970's, remote sensing was used to map road surface distress, while during the last decade, remote sensing became more advanced, thereby assisting in the evolution of the identification and mapping of roads. Various techniques were used in order to explore condition, age, weaknesses and imperfections of asphalted pavements. These methods were fairly successful in the classification of asphalted surfaces and in the detection of some of their characteristics. This paper explores the state of the art of using remote sensing techniques for monitoring damaged pavements and some typical spectral profiles of various asphalt pavements in Cyprus area acquired using the SVC1024 field spectroradiometer.

  4. New techniques of low level environmental radiation monitoring at JLab

    SciTech Connect

    P. Degtiarenko, V. Popov

    2010-07-01

    We present the first long-term environmental radiation monitoring results obtained using the technique of pulse mode readout for the industry-standard Reuter-Stokes RSS-1013 argon-filled high pressure ionization chambers (HPIC). With novel designs for the front-end electronics readout and customized signal processing algorithms, we are capable of detecting individual events of gas ionization in the HPIC, caused by interactions of gammas and charged particles in the gas. The technique provides enough spectroscopic information to distinguish between several different types of environmental and man-made radiation. The technique also achieves a high degree of sensitivity and stability of the data, allowing long-term environmental radiation monitoring with unprecedented precision.

  5. Condition Monitoring of Cables Task 3 Report: Condition Monitoring Techniques for Electric Cables

    SciTech Connect

    Villaran, M.; Lofaro, R.; na

    2009-11-30

    For more than 20 years the NRC has sponsored research studying electric cable aging degradation, condition monitoring, and environmental qualification testing practices for electric cables used in nuclear power plants. This report summarizes several of the most effective and commonly used condition monitoring techniques available to detect damage and measure the extent of degradation in electric cable insulation. The technical basis for each technique is summarized, along with its application, trendability of test data, ease of performing the technique, advantages and limitations, and the usefulness of the test results to characterize and assess the condition of electric cables.

  6. Sound field separation technique based on equivalent source method and its application in nearfield acoustic holography.

    PubMed

    Bi, Chuan-Xing; Chen, Xin-Zhao; Chen, Jian

    2008-03-01

    A technique for separating sound fields using two closely spaced parallel measurement surfaces and based on equivalent source method is proposed. The method can separate wave components crossing two measurement surfaces in opposite directions, which makes nearfield acoustic holography (NAH) applications in a field where there exist sources on the two sides of the hologram surface, in a reverberant field or in a scattered field, possible. The method is flexible in applications, simple in computation, and very easy to implement. The measurement surfaces can be arbitrarily shaped, and they are not restricted to be regular as in the traditional field separation technique. And, because the method performs field separation calculations directly in the spatial domain-not in the wave number domain--it avoids the errors and limitations (the window effects, etc.) associated with the traditional field separation technique based on the spatial Fourier transform method. In the paper, a theoretical description is first given, and the performance of the proposed field separation technique and its application in NAH are then evaluated through experiments.

  7. Acoustic Emission Weld Monitoring in the 2195 Aluminum-Lithium Alloy

    NASA Technical Reports Server (NTRS)

    Walker, James L.

    2005-01-01

    Due to its low density, the 2195 aluminum-lithium alloy was developed as a replacement for alloy 2219 in the Space Shuttle External Tank (ET). The external tank is the single largest component of the space shuttle system. It is 154 feet long and 27.6 feet in diameter, and serves as the structural backbone for the shuttle during launch, absorbing most of the 7 million plus pounds of thrust produced. The almost 4% decrease in density between the two materials provides an extra 7500 pounds of payload capacity necessary to put the International Space Station components into orbit. The ET is an all-welded structure; hence, the requirement is for up to five rewelds without hot cracking. Unfortunately, hot cracking during re-welding or repair operations was occurring and had to be dealt with before the new super lightweight tank could be used. Weld metal porosity formation was also of concern because it leads to hot cracking during weld repairs. Accordingly, acoustic emission (AE) nondestructive testing was employed to monitor the formation of porosity and hot cracks in order to select the best filler metal and optimize the weld schedule. The purpose of this work is to determine the feasibility of detecting hot cracking in welded aluminum-lithium (Al-Li) structures through the analysis of acoustic emission data. By acoustically characterizing the effects of reheating during a repair operation, the potential for hidden flaws coalescing and becoming "unstable" as the panel is repaired could be reduced. Identification of regions where microcrack growth is likely to occur and the location of active flaw growth in the repair weld will provide the welder with direct feedback as to the current weld quality enabling adjustments to the repair process be made in the field. An acoustic emission analysis of the source mechanisms present during welding has been conducted with the goals of locating regions in the weld line that are susceptible to damage from a repair operation

  8. Acoustic Monitoring of Ebullitive Flux from a Mire Ecosystem in Subarctic Sweden

    NASA Astrophysics Data System (ADS)

    Burke, S. A.; Varner, R. K.; Palace, M. W.; Wik, M.; Crill, P. M.; McCalley, C. K.; Amante, J.

    2012-12-01

    Methane (CH4) is a potent green house gas with wetlands being the largest natural source to the atmosphere. Studies in the Stordalen Mire, a dynamic peatland complex 11km east of the Abisko Scientific Research Station (ANS) in northern Sweden, that focused on CH4 transport to the atmosphere from peatlands have shown increased emissions over the past decades. Ebullitive flux (bubbling) is a potentially significant pathway of CH4 from mire/lake ecosystems. Ebullitive fluxes were successfully monitored acoustically in peat and lakes in 2011. This work expands those measurements with installation of sensors in ponds and permafrost thaw margins in 2012. Eighteen acoustic sensors were installed in peat (6), pond (6), and lake (6) sites at Stordalen Mire. Recorders collected acoustic data continuously from each sensor and gas samples were collected from the traps at least once per week beginning 7 July. The CH4 concentration in the gas was measured using gas chromatography and selected samples were also analyzed for 13C-CH4 using a Quantum Cascade Laser (QCL). The acoustic data were evaluated using a MATLAB program for determine the timing and volume of each ebullition event. The CH4 ebullitive flux from the peat was greater in July 2011 than during the same period in 2012. In comparison, the ponds and thaw margins released CH4 at a faster rate in 2012 than was observed in the peat and lake sensors in 2011. Inter-annual differences in ebullitive rates suggest that weather scale differences between years may control CH4 ebullitive flux. 13C-CH4 measured in the pore waters of pond sediment suggests that not all ponds are dominated by the same production processes. However, 13C-CH4 measured in bubbles and sediments are not different, implying little or no oxidation of CH4 during transport to the water surface. Our data suggests that changes in atmospheric pressure and water table height correlated with the ebullitive release in all three sub-ecosystems.

  9. Acoustic Telemetry Validates a Citizen Science Approach for Monitoring Sharks on Coral Reefs

    PubMed Central

    Vianna, Gabriel M. S.; Meekan, Mark G.; Bornovski, Tova H.; Meeuwig, Jessica J.

    2014-01-01

    Citizen science is promoted as a simple and cost-effective alternative to traditional approaches for the monitoring of populations of marine megafauna. However, the reliability of datasets collected by these initiatives often remains poorly quantified. We compared datasets of shark counts collected by professional dive guides with acoustic telemetry data from tagged sharks collected at the same coral reef sites over a period of five years. There was a strong correlation between the number of grey reef sharks (Carcharhinus amblyrhynchos) observed by dive guides and the telemetry data at both daily and monthly intervals, suggesting that variation in relative abundance of sharks was detectable in datasets collected by dive guides in a similar manner to data derived from telemetry at these time scales. There was no correlation between the number or mean depth of sharks recorded by telemetry and the presence of tourist divers, suggesting that the behaviour of sharks was not affected by the presence of divers during our study. Data recorded by dive guides showed that current strength and temperature were important drivers of the relative abundance of sharks at monitored sites. Our study validates the use of datasets of shark abundance collected by professional dive guides in frequently-visited dive sites in Palau, and supports the participation of experienced recreational divers as contributors to long-term monitoring programs of shark populations. PMID:24760081

  10. Acoustic telemetry validates a citizen science approach for monitoring sharks on coral reefs.

    PubMed

    Vianna, Gabriel M S; Meekan, Mark G; Bornovski, Tova H; Meeuwig, Jessica J

    2014-01-01

    Citizen science is promoted as a simple and cost-effective alternative to traditional approaches for the monitoring of populations of marine megafauna. However, the reliability of datasets collected by these initiatives often remains poorly quantified. We compared datasets of shark counts collected by professional dive guides with acoustic telemetry data from tagged sharks collected at the same coral reef sites over a period of five years. There was a strong correlation between the number of grey reef sharks (Carcharhinus amblyrhynchos) observed by dive guides and the telemetry data at both daily and monthly intervals, suggesting that variation in relative abundance of sharks was detectable in datasets collected by dive guides in a similar manner to data derived from telemetry at these time scales. There was no correlation between the number or mean depth of sharks recorded by telemetry and the presence of tourist divers, suggesting that the behaviour of sharks was not affected by the presence of divers during our study. Data recorded by dive guides showed that current strength and temperature were important drivers of the relative abundance of sharks at monitored sites. Our study validates the use of datasets of shark abundance collected by professional dive guides in frequently-visited dive sites in Palau, and supports the participation of experienced recreational divers as contributors to long-term monitoring programs of shark populations. PMID:24760081

  11. Acoustic telemetry validates a citizen science approach for monitoring sharks on coral reefs.

    PubMed

    Vianna, Gabriel M S; Meekan, Mark G; Bornovski, Tova H; Meeuwig, Jessica J

    2014-01-01

    Citizen science is promoted as a simple and cost-effective alternative to traditional approaches for the monitoring of populations of marine megafauna. However, the reliability of datasets collected by these initiatives often remains poorly quantified. We compared datasets of shark counts collected by professional dive guides with acoustic telemetry data from tagged sharks collected at the same coral reef sites over a period of five years. There was a strong correlation between the number of grey reef sharks (Carcharhinus amblyrhynchos) observed by dive guides and the telemetry data at both daily and monthly intervals, suggesting that variation in relative abundance of sharks was detectable in datasets collected by dive guides in a similar manner to data derived from telemetry at these time scales. There was no correlation between the number or mean depth of sharks recorded by telemetry and the presence of tourist divers, suggesting that the behaviour of sharks was not affected by the presence of divers during our study. Data recorded by dive guides showed that current strength and temperature were important drivers of the relative abundance of sharks at monitored sites. Our study validates the use of datasets of shark abundance collected by professional dive guides in frequently-visited dive sites in Palau, and supports the participation of experienced recreational divers as contributors to long-term monitoring programs of shark populations.

  12. Passive acoustic monitoring of beaked whale densities in the Gulf of Mexico.

    PubMed

    Hildebrand, John A; Baumann-Pickering, Simone; Frasier, Kaitlin E; Trickey, Jennifer S; Merkens, Karlina P; Wiggins, Sean M; McDonald, Mark A; Garrison, Lance P; Harris, Danielle; Marques, Tiago A; Thomas, Len

    2015-11-12

    Beaked whales are deep diving elusive animals, difficult to census with conventional visual surveys. Methods are presented for the density estimation of beaked whales, using passive acoustic monitoring data collected at sites in the Gulf of Mexico (GOM) from the period during and following the Deepwater Horizon oil spill (2010-2013). Beaked whale species detected include: Gervais' (Mesoplodon europaeus), Cuvier's (Ziphius cavirostris), Blainville's (Mesoplodon densirostris) and an unknown species of Mesoplodon sp. (designated as Beaked Whale Gulf - BWG). For Gervais' and Cuvier's beaked whales, we estimated weekly animal density using two methods, one based on the number of echolocation clicks, and another based on the detection of animal groups during 5 min time-bins. Density estimates derived from these two methods were in good general agreement. At two sites in the western GOM, Gervais' beaked whales were present throughout the monitoring period, but Cuvier's beaked whales were present only seasonally, with periods of low density during the summer and higher density in the winter. At an eastern GOM site, both Gervais' and Cuvier's beaked whales had a high density throughout the monitoring period.

  13. Passive acoustic monitoring of beaked whale densities in the Gulf of Mexico

    PubMed Central

    Hildebrand, John A.; Baumann-Pickering, Simone; Frasier, Kaitlin E.; Trickey, Jennifer S.; Merkens, Karlina P.; Wiggins, Sean M.; McDonald, Mark A.; Garrison, Lance P.; Harris, Danielle; Marques, Tiago A.; Thomas, Len

    2015-01-01

    Beaked whales are deep diving elusive animals, difficult to census with conventional visual surveys. Methods are presented for the density estimation of beaked whales, using passive acoustic monitoring data collected at sites in the Gulf of Mexico (GOM) from the period during and following the Deepwater Horizon oil spill (2010–2013). Beaked whale species detected include: Gervais’ (Mesoplodon europaeus), Cuvier’s (Ziphius cavirostris), Blainville’s (Mesoplodon densirostris) and an unknown species of Mesoplodon sp. (designated as Beaked Whale Gulf — BWG). For Gervais’ and Cuvier’s beaked whales, we estimated weekly animal density using two methods, one based on the number of echolocation clicks, and another based on the detection of animal groups during 5 min time-bins. Density estimates derived from these two methods were in good general agreement. At two sites in the western GOM, Gervais’ beaked whales were present throughout the monitoring period, but Cuvier’s beaked whales were present only seasonally, with periods of low density during the summer and higher density in the winter. At an eastern GOM site, both Gervais’ and Cuvier’s beaked whales had a high density throughout the monitoring period. PMID:26559743

  14. Validation of an acoustic location system to monitor Bornean orangutan (Pongo pygmaeus wurmbii) long calls.

    PubMed

    Spillmann, Brigitte; van Noordwijk, Maria A; Willems, Erik P; Mitra Setia, Tatang; Wipfli, Urs; van Schaik, Carel P

    2015-07-01

    The long call is an important vocal communication signal in the widely dispersed, semi-solitary orangutan. Long calls affect individuals' ranging behavior and mediate social relationships and regulate encounters between dispersed individuals in a dense rainforest. The aim of this study was to test the utility of an Acoustic Location System (ALS) for recording and triangulating the loud calls of free-living primates. We developed and validated a data extraction protocol for an ALS used to record wild orangutan males' long calls at the Tuanan field site (Central Kalimantan). We installed an ALS in a grid of 300 ha, containing 20 SM2+ recorders placed in a regular lattice at 500 m intervals, to monitor the distribution of calling males in the area. The validated system had the following main features: (i) a user-trained software algorithm (Song Scope) that reliably recognized orangutan long calls from sound files at distances up to 700 m from the nearest recorder, resulting in a total area of approximately 900 ha that could be monitored continuously; (ii) acoustic location of calling males up to 200 m outside the microphone grid, which meant that within an area of approximately 450 ha, call locations could be calculated through triangulation. The mean accuracy was 58 m, an error that is modest relative to orangutan mobility and average inter-individual distances. We conclude that an ALS is a highly effective method for detecting long-distance calls of wild primates and triangulating their position. In combination with conventional individual focal follow data, an ALS can greatly improve our knowledge of orangutans' social organization, and is readily adaptable for studying other highly vocal animals.

  15. Jitter reduction technique for acoustic radiation force impulse microscopy via photoacoustic detection

    PubMed Central

    Kang, Bong Jin; Yoon, Changhan; Man Park, Jin; Hwang, Jae Youn; Shung, K. Kirk

    2015-01-01

    We demonstrate a jitter noise reduction technique for acoustic radiation force impulse microscopy via photoacoustic detection (PA-ARFI), which promises to be capable of measuring cell mechanics. To reduce the jitter noise induced by Q-switched pulsed laser operated at high repetition frequency, photoacoustic signals from the surface of an ultrasound transducer are aligned by cross-correlation and peak-to-peak detection, respectively. Each method is then employed to measure the displacements of a target sample in an agar phantom and a breast cancer cell due to ARFI application, followed by the quantitative comparison between their performances. The suggested methods for PA-ARFI significantly reduce jitter noises, thus allowing us to measure displacements of a target cell due to ARFI application by less than 3 μm. PMID:26367579

  16. Stellar acoustic radii, mean densities, and ages from seismic inversion techniques

    NASA Astrophysics Data System (ADS)

    Buldgen, G.; Reese, D. R.; Dupret, M. A.; Samadi, R.

    2015-01-01

    Context. Determining stellar characteristics such as the radius, mass or age is crucial when studying stellar evolution or exoplanetary systems, or when characterising stellar populations in the Galaxy. Asteroseismology is the golden path to accurately obtain these characteristics. In this context, a key question is how to make these methods less model-dependent. Aims: Building on the previous work of Daniel Reese, we wish to extend the Substractive Optimally Localized Averages (SOLA) inversion technique to new stellar global characteristics beyond the mean density. The goal is to provide a general framework in which to estimate these characteristics as accurately as possible in low-mass main-sequence stars. Methods: First, we describe our framework and discuss the reliability of the inversion technique and possible sources of error. We then apply this methodology to the acoustic radius, an age indicator based on the sound speed derivative and the mean density, and compare it to estimates based on the average large and small frequency separations. These inversions are carried out for several test cases including various metallicities, different mixing-lengths, non-adiabatic effects, and turbulent pressure. Results: We observe that the SOLA method yields accurate results in all test cases whereas results based on the large and small frequency separations are less accurate and more sensitive to surface effects and structural differences in the models. If we include the surface corrections of Kjeldsen et al. (2008, ApJ, 683, L175), we obtain results of comparable accuracy for the mean density. Overall, the mean density and acoustic radius inversions are more robust than the inversions for the age indicator. Moreover, the current approach is limited to relatively young stars with radiative cores. Increasing the number of observed frequencies improves the reliability and accuracy of the method. Appendices are available in electronic form at http://www.aanda.org

  17. Data-driven nonlinear technique for condition monitoring

    SciTech Connect

    Hively, L.M.

    1997-04-01

    This paper describes a sensitive technique for distinguishing changes in a nonlinear process. The method obtains a phase-space (PS) representation of the process, which in turn is converted into a probability density function (PDF). Condition change is monitored by comparing two PS-PDFs via a {chi}{sup 2} statistical measure. One example application involves monitoring of brain waves to distinguish various states in an epileptic patient. A second example distinguishes different drilling conditions from spindle motor current data. A third example distinguishes balanced and unbalanced pumping conditions from power data.

  18. Advanced Process Monitoring Techniques for Safeguarding Reprocessing Facilities

    SciTech Connect

    Orton, Christopher R.; Bryan, Samuel A.; Schwantes, Jon M.; Levitskaia, Tatiana G.; Fraga, Carlos G.; Peper, Shane M.

    2010-11-30

    The International Atomic Energy Agency (IAEA) has established international safeguards standards for fissionable material at spent fuel reprocessing plants to ensure that significant quantities of weapons-grade nuclear material are not diverted from these facilities. For large throughput nuclear facilities, it is difficult to satisfy the IAEA safeguards accountancy goal for detection of abrupt diversion. Currently, methods to verify material control and accountancy (MC&A) at these facilities require time-consuming and resource-intensive destructive assay (DA). Leveraging new on-line non destructive assay (NDA) process monitoring techniques in conjunction with the traditional and highly precise DA methods may provide an additional measure to nuclear material accountancy which would potentially result in a more timely, cost-effective and resource efficient means for safeguards verification at such facilities. By monitoring process control measurements (e.g. flowrates, temperatures, or concentrations of reagents, products or wastes), abnormal plant operations can be detected. Pacific Northwest National Laboratory (PNNL) is developing on-line NDA process monitoring technologies, including both the Multi-Isotope Process (MIP) Monitor and a spectroscopy-based monitoring system, to potentially reduce the time and resource burden associated with current techniques. The MIP Monitor uses gamma spectroscopy and multivariate analysis to identify off-normal conditions in process streams. The spectroscopic monitor continuously measures chemical compositions of the process streams including actinide metal ions (U, Pu, Np), selected fission products, and major cold flowsheet chemicals using UV-Vis, Near IR and Raman spectroscopy. This paper will provide an overview of our methods and report our on-going efforts to develop and demonstrate the technologies.

  19. Characterization of acoustic effects on flame structures by beam deflection technique

    SciTech Connect

    Bedat, B.; Kostiuk, L.W.; Cheng, R.K.

    1993-10-01

    This work shows that the acoustic effects are the causes of the small amplitude flame wrinkling and movements seen in all the different gravitational conditions. The comparison between the acoustic velocity and beam deflection spectra for the two conditions studied (glass beads and fiber glass) demonstrates clearly this flame/acoustic coupling. This acoustic study shows that the burner behaves like a Helmholtz resonator. The estimated resonance frequency corresponds well to the experimental measurements. The fiber glass damps the level of the resonance frequency and the flame motion. The changes shown in normalized beam deflection spectra give further support of this damping. This work demonstrates that the acoustics has a direct influence on flame structure in the laminar case and the preliminary results in turbulent case also show a strong coupling. The nature of this flame/acoustic coupling are still not well understood. Further investigation should include determining the frequency limits and the sensitivity of the flame to acoustic perturbations.

  20. A simulation technique for 3D MR-guided acoustic radiation force imaging

    SciTech Connect

    Payne, Allison; Bever, Josh de; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-02-15

    Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation force field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Green’s function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Green’s function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30- and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.028–0.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison

  1. Calibrating passive acoustic monitoring: correcting humpback whale call detections for site-specific and time-dependent environmental characteristics.

    PubMed

    Helble, Tyler A; D'Spain, Gerald L; Campbell, Greg S; Hildebrand, John A

    2013-11-01

    This paper demonstrates the importance of accounting for environmental effects on passive underwater acoustic monitoring results. The situation considered is the reduction in shipping off the California coast between 2008-2010 due to the recession and environmental legislation. The resulting variations in ocean noise change the probability of detecting marine mammal vocalizations. An acoustic model was used to calculate the time-varying probability of detecting humpback whale vocalizations under best-guess environmental conditions and varying noise. The uncorrected call counts suggest a diel pattern and an increase in calling over a two-year period; the corrected call counts show minimal evidence of these features.

  2. Clinical Studies of Real-Time Monitoring of Lithotripter Performance Using Passive Acoustic Sensors

    NASA Astrophysics Data System (ADS)

    Leighton, T. G.; Fedele, F.; Coleman, A. J.; McCarthy, C.; Ryves, S.; Hurrell, A. M.; De Stefano, A.; White, P. R.

    2008-09-01

    This paper describes the development and clinical testing of a passive device which monitors the passive acoustic emissions generated within the patient's body during Extracorporeal Shock Wave Lithotripsy (ESWL). Designed and clinically tested so that it can be operated by a nurse, the device analyses the echoes generated in the body in response to each ESWL shock, and so gives real time shock-by-shock feedback on whether the stone was at the focus of the lithotripter, and if so whether the previous shock contributed to stone fragmentation when that shock reached the focus. A shock is defined as being `effective' if these two conditions are satisfied. Not only can the device provide real-time feedback to the operator, but the trends in shock `effectiveness' can inform treatment. In particular, at any time during the treatment (once a statistically significant number of shocks have been delivered), the percentage of shocks which were `effective' provides a treatment score TS(t) which reflects the effectiveness of the treatment up to that point. The TS(t) figure is automatically delivered by the device without user intervention. Two clinical studies of the device were conducted, the ethics guidelines permitting only use of the value of TS(t) obtained at the end of treatment (this value is termed the treatment score TS0). The acoustically-derived treatment score was compared with the treatment score CTS2 given by the consultant urologist at the three-week patient's follow-up appointment. In the first clinical study (phase 1), records could be compared for 30 out of the 118 patients originally recruited, and the results of phase 1 were used to refine the parameter values (the `rules') with which the acoustic device provides its treatment score. These rules were tested in phase 2, for which records were compared for 49 of the 85 patients recruited. Considering just the phase 2 results (since the phase 1 data were used to draw up the `rules' under which phase 2 operated

  3. Environmental influences on the spatial ecology of juvenile smalltooth sawfish (Pristis pectinata): results from acoustic monitoring.

    PubMed

    Simpfendorfer, Colin A; Yeiser, Beau G; Wiley, Tonya R; Poulakis, Gregg R; Stevens, Philip W; Heupel, Michelle R

    2011-01-01

    To aid recovery efforts of smalltooth sawfish (Pristis pectinata) populations in U.S. waters a research project was developed to assess how changes in environmental conditions within estuarine areas affected the presence, movements, and activity space of this endangered species. Forty juvenile P. pectinata were fitted with acoustic tags and monitored within the lower 27 km of the Caloosahatchee River estuary, Florida, between 2005 and 2007. Sawfish were monitored within the study site from 1 to 473 days, and the number of consecutive days present ranged from 1 to 125. Residency index values for individuals varied considerably, with annual means highest in 2005 (0.95) and lowest in 2007 (0.73) when several P. pectinata moved upriver beyond detection range during drier conditions. Mean daily activity space was 1.42 km of river distance. The distance between 30-minute centers of activity was typically <0.1 km, suggesting limited movement over short time scales. Salinity electivity analysis demonstrated an affinity for salinities between 18 and at least 24 psu, suggesting movements are likely made in part, to remain within this range. Thus, freshwater flow from Lake Okeechobee (and its effect on salinity) affects the location of individuals within the estuary, although it remains unclear whether or not these movements are threatening recovery.

  4. Acoustic monitoring in the Ross Sea, Antarctica, using hydrophone of the Ocean Bottom Seismometer

    NASA Astrophysics Data System (ADS)

    Yun, Sukyoung; Lee, Won Sang; Kuk Hong, Jong; Yoo, Hyun Jae; Park, Yongcheol; Schmidt-Aursch, Mechita; Geissler, Wolfram H.

    2016-04-01

    Although a number of active source seismic experiments have been conducted over the last few decades to investigate the crustal structure in the Ross Sea, Antarctica, long-term observation to monitor underwater tectonic activities and changes in the cryospheric environment still remains challenging due to existence of sea ice in the study region. Korea Polar Research Institute has accomplished successful deployment of ocean bottom seismometers (OBS) in the Ross Sea collaborating with Alfred Wegener Institute during the period of 2011-2012 and 2014 by Korean icebreaker RV Araon. The OBS system manufactured by K.U.M. contains a hydrophone sensor that allow us to monitor underwater acoustics generated by tectonic and ice-related events. We present spectrograms of the continuous hydroacoustic data and various types of signals, e.g. seismic T-waves, iceequakes, and tremors. There are periodic and harmonic tremors that might be related with tidal modulation, and the seasonal variation of the background noise seems to be related with sea ice concentration.

  5. Application of acoustical thermometry to noninvasive monitoring of internal temperature during laser hyperthermia

    NASA Astrophysics Data System (ADS)

    Krotov, Eugene V.; Yakovlev, Ivan V.; Zhadobov, Maxim; Reyman, Alexander M.; Zharov, Vladimir P.

    2002-06-01

    This work present the results of experimental study of applicability of acoustical brightness thermometry (ABT) in monitoring of internal temperature during laser hyperthermia and interstitial therapy. In these experiments the radiation of pulse repetition Nd:YAG laser (1064 nm) and continuous diode laser (800 nm) were used as heating sources. Experiments were performed in vitro by insertion of optical fiber inside the objects - optically transparent gelatin with incorporated light absorbing heterogeneities and samples of biological tissues (e.g. liver). During laser heating, internal temperature in absorbing heterogeneity and at fiber end were monitored by means of multi-channel ABT. The independent temperature control was performed with tiny electronic thermometer incorporated in heated zones. The results of experiments demonstrated reasonable sensitivity and accuracy of ABT for real-time temperature control during different kind of laser thermal therapies. According to preliminary data, ABT allow to measure temperature in depth up to 3-5 cm (depends on tissue properties) with spatial resolution some mm. Obtained data show that ABT is a very promising tool to give quantitative measure for different types of energy deposition (laser, microwave, focused ultrasound etc) at the depth commonly encountered in tumors of vital organs. Besides, ABT could give information about diffusion effects in heated zones or optical absorption. This work was supported by Russian Foundation for Basic Research and 6th competition-expertise of young scientists of Russian Academy of Sciences.

  6. Remote monitoring and prognosis of fatigue cracking in steel bridges with acoustic emission

    NASA Astrophysics Data System (ADS)

    Yu, Jianguo Peter; Ziehl, Paul; Pollock, Adrian

    2011-04-01

    Acoustic emission (AE) monitoring is desirable to nondestructively detect fatigue damage in steel bridges. Investigations of the relationship between AE signals and crack growth behavior are of paramount importance prior to the widespread application of passive piezoelectric sensing for monitoring of fatigue crack propagation in steel bridges. Tests have been performed to detect AE from fatigue cracks in A572G50 steel. Noise induced AE signals were filtered based on friction emission tests, loading pattern, and a combined approach involving Swansong II filters and investigation of waveforms. The filtering methods based on friction emission tests and load pattern are of interest to the field evaluation using sparse datasets. The combined approach is suitable for data filtering and interpretation of actual field tests. The pattern recognition program NOESIS (Envirocoustics) was utilized for the evaluation of AE data quality. AE parameters are associated with crack length, crack growth rate, maximum stress intensity and stress intensity range. It is shown that AE hits, counts, absolute energy, and signal strength are able to provide warnings at the critical cracking level where cracking progresses from stage II (stable propagation) to stage III (unstable propagation which may result in failure). Absolute energy rate and signal strength rate may be better than count rate to assess the remaining fatigue life of inservice steel bridges.

  7. Environmental Influences on the Spatial Ecology of Juvenile Smalltooth Sawfish (Pristis pectinata): Results from Acoustic Monitoring

    PubMed Central

    Simpfendorfer, Colin A.; Yeiser, Beau G.; Wiley, Tonya R.; Poulakis, Gregg R.; Stevens, Philip W.; Heupel, Michelle R.

    2011-01-01

    To aid recovery efforts of smalltooth sawfish (Pristis pectinata) populations in U.S. waters a research project was developed to assess how changes in environmental conditions within estuarine areas affected the presence, movements, and activity space of this endangered species. Forty juvenile P. pectinata were fitted with acoustic tags and monitored within the lower 27 km of the Caloosahatchee River estuary, Florida, between 2005 and 2007. Sawfish were monitored within the study site from 1 to 473 days, and the number of consecutive days present ranged from 1 to 125. Residency index values for individuals varied considerably, with annual means highest in 2005 (0.95) and lowest in 2007 (0.73) when several P. pectinata moved upriver beyond detection range during drier conditions. Mean daily activity space was 1.42 km of river distance. The distance between 30-minute centers of activity was typically <0.1 km, suggesting limited movement over short time scales. Salinity electivity analysis demonstrated an affinity for salinities between 18 and at least 24 psu, suggesting movements are likely made in part, to remain within this range. Thus, freshwater flow from Lake Okeechobee (and its effect on salinity) affects the location of individuals within the estuary, although it remains unclear whether or not these movements are threatening recovery. PMID:21347294

  8. Environmental influences on the spatial ecology of juvenile smalltooth sawfish (Pristis pectinata): results from acoustic monitoring.

    PubMed

    Simpfendorfer, Colin A; Yeiser, Beau G; Wiley, Tonya R; Poulakis, Gregg R; Stevens, Philip W; Heupel, Michelle R

    2011-01-01

    To aid recovery efforts of smalltooth sawfish (Pristis pectinata) populations in U.S. waters a research project was developed to assess how changes in environmental conditions within estuarine areas affected the presence, movements, and activity space of this endangered species. Forty juvenile P. pectinata were fitted with acoustic tags and monitored within the lower 27 km of the Caloosahatchee River estuary, Florida, between 2005 and 2007. Sawfish were monitored within the study site from 1 to 473 days, and the number of consecutive days present ranged from 1 to 125. Residency index values for individuals varied considerably, with annual means highest in 2005 (0.95) and lowest in 2007 (0.73) when several P. pectinata moved upriver beyond detection range during drier conditions. Mean daily activity space was 1.42 km of river distance. The distance between 30-minute centers of activity was typically <0.1 km, suggesting limited movement over short time scales. Salinity electivity analysis demonstrated an affinity for salinities between 18 and at least 24 psu, suggesting movements are likely made in part, to remain within this range. Thus, freshwater flow from Lake Okeechobee (and its effect on salinity) affects the location of individuals within the estuary, although it remains unclear whether or not these movements are threatening recovery. PMID:21347294

  9. Acoustic emission detection with fiber optical sensors for dry cask storage health monitoring

    NASA Astrophysics Data System (ADS)

    Lin, Bin; Bao, Jingjing; Yu, Lingyu; Giurgiutiu, Victor

    2016-04-01

    The increasing number, size, and complexity of nuclear facilities deployed worldwide are increasing the need to maintain readiness and develop innovative sensing materials to monitor important to safety structures (ITS). In the past two decades, an extensive sensor technology development has been used for structural health monitoring (SHM). Technologies for the diagnosis and prognosis of a nuclear system, such as dry cask storage system (DCSS), can improve verification of the health of the structure that can eventually reduce the likelihood of inadvertently failure of a component. Fiber optical sensors have emerged as one of the major SHM technologies developed particularly for temperature and strain measurements. This paper presents the development of optical equipment that is suitable for ultrasonic guided wave detection for active SHM in the MHz range. An experimental study of using fiber Bragg grating (FBG) as acoustic emission (AE) sensors was performed on steel blocks. FBG have the advantage of being durable, lightweight, and easily embeddable into composite structures as well as being immune to electromagnetic interference and optically multiplexed. The temperature effect on the FBG sensors was also studied. A multi-channel FBG system was developed and compared with piezoelectric based AE system. The paper ends with conclusions and suggestions for further work.

  10. Challenge of Using Passive Acoustic Monitoring in High-Energy Environments: UK Tidal Environments and Other Case Studies.

    PubMed

    Booth, Cormac G

    2016-01-01

    The use of passive acoustic monitoring (PAM) around marine developments is commonplace. A buffer-based PAM system (e.g., C-POD) is a cost-effective method for assessing cetacean acoustic presence. Devices have been deployed by Sea Mammal Research Unit (SMRU) Marine around the United Kingdom, allowing an examination of the performance of C-PODs with respect to background noise, tilt angle, and environmental factors. C-PODs were found to often only monitor for a few seconds of each minute, resulting in significant loss of monitoring time. Issues were likely driven by environmental and deployment factors. The practical limitations of buffer-based PAM systems in high-energy/noisy environments are indicated here.

  11. Challenge of Using Passive Acoustic Monitoring in High-Energy Environments: UK Tidal Environments and Other Case Studies.

    PubMed

    Booth, Cormac G

    2016-01-01

    The use of passive acoustic monitoring (PAM) around marine developments is commonplace. A buffer-based PAM system (e.g., C-POD) is a cost-effective method for assessing cetacean acoustic presence. Devices have been deployed by Sea Mammal Research Unit (SMRU) Marine around the United Kingdom, allowing an examination of the performance of C-PODs with respect to background noise, tilt angle, and environmental factors. C-PODs were found to often only monitor for a few seconds of each minute, resulting in significant loss of monitoring time. Issues were likely driven by environmental and deployment factors. The practical limitations of buffer-based PAM systems in high-energy/noisy environments are indicated here. PMID:26610949

  12. Complex monitoring and alert network for electromagnetic, infrasound, acoustic seismotectonic phenomena

    NASA Astrophysics Data System (ADS)

    -Emilian Toader, Victorin; Moldovan, Iren-Adelina; Constantin, Ionescu

    2014-05-01

    The Romanian seismicity recorded in 2013 three important events: the largest seismic "silence", the shortest sequence of two earthquakes greater than 4.8R in less than 14 days after the "Romanian National Institute for Earth Physics" (NIEP) developed a digital network, and a very high crustal activity in Galati area. We analyze the variations of the telluric currents and local magnetic field, variations of the atmospheric electrostatic field, infrasound, temperature, humidity, wind speed and direction, atmospheric pressure, variations in the earth crust with inclinometers and animal behavior. The general effect is the first high seismic energy discontinuity that could be a precursor factor. Since 1977 Romania did not register any important earthquake that would generate a sense of fear among the population. In parallel with the seismic network NIEP developed a magneto-telluric, bioseismic, VLF and acoustic network. A large frequency spectrum is covered for mechanical vibration, magnetic and electric field with ground and air sensors. Special software was designed for acquisition, analysis and real time alert using internet direct connection, web page, email and SMS. Many examples show the sensitivity of telluric current, infrasound, acoustic records (from air-ground), and the effect of tectonic stress on the magnetic field or ground deformation. The next update of the multidisciplinary monitoring network will include measurement of ionization, radon emission, sky color, solar radiation and extension of infrasound and VL/LF equipment. NOAA Space Weather satellites transmit solar activity magnetic field data, X ray flux, electron, and proton flux information useful for complex analysis.

  13. Mechanical Weakening during Fluid Injection in Critically Stressed Sandstones with Acoustic Monitoring

    NASA Astrophysics Data System (ADS)

    David, C.; Dautriat, J. D.; Sarout, J.; Macault, R.; Bertauld, D.

    2014-12-01

    Water weakening is a well-known phenomenon which can lead to subsidence during the production of hydrocarbon reservoirs. The example of the Ekofisk oil field in the North Sea has been well documented for years. In order to assess water weakening effects in reservoir rocks, previous studies have focused on changes in the failure envelopes derived from mechanical tests conducted on rocks saturated either with water or with inert fluids. However, little attention has been paid so far on the mechanical behaviour during the fluid injection stage, like in enhanced oil recovery operations. We studied the effect of fluid injection on the mechanical behaviour of Sherwood sandstone, a weakly-consolidated sandstone sampled at Ladram Bay in UK. In order to highlight possible weakening effects, water and inert oil have been injected into critically-loaded samples to assess their effect on strength and elastic properties and to derive the acoustic signature of the saturation front for each fluid. The specimens were instrumented with 16 ultrasonic P-wave transducers for both passive and active acoustic monitoring during fluid injection and loading. After conducting standard triaxial tests on three samples saturated with air, water and oil respectively, mechanical creep tests were conducted on dry samples loaded at 80% of the compressive strength of the dry rock. While these conditions are kept constant, a fluid is injected at the bottom end of the sample with a low back pressure (0.5 MPa) to minimize effective stress variations during injection. Both water and oil were used as the injected pore fluid in two experiments. As soon as the fluids start to flow into the samples, creep is taking place with a much higher strain rate for water injection compared to oil injection. A transition from secondary creep to tertiary creep is observed in the water injection test whereas in the oil injection test no significant creep acceleration is observed after one pore volume of oil was

  14. Atmospheric trace gases monitoring by UV-vis spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Xie, Pinhua; Li, Ang; Wu, Fengcheng; Qin, Min; Hu, Rezhi; Xu, Jin; Si, Fuqi; Liu, Jianguo; Liu, Wenqing

    2016-04-01

    Due to rapidly economic development, air pollution has become an important issue in China. Phenomena such as regional haze in winter and high O3 concentration in summer are strongly related to increasing trace species. For better understanding the air pollution formation, it is necessary to know spatial and temporal distribution of trace species in the atmosphere. UV-vis spectroscopic techniques are of great advantages for trace species monitoring to meet several requirements, e.g. versatility, high sensitivity, good temporal resolution and field applicability. We have studied and developed various trace gases monitoring techniques and instruments based on UV-vis spectroscopic technique for in-situ measurements and remote sensing, e.g. LP-DOAS, IBBCEAS, CRDS, MAX-DOAS and mobile DOAS for NO2, SO2, HCHO, HONO, NO3, and N2O5 etc. The principle, instrumentation and inversion algorithm are presented. As typical applications of these techniques, investigation of the evolution of HONO and NO3 radicals over Beijing area, measurements of regional pollution in NCP and YRD are discussed in the aspects of HONO and nocturnal NO3 radical characteristics, trace gases (NO2, SO2 etc.) temporal and spatial distribution, pollution transport pathway, emission sources.

  15. Investigation of contact acoustic nonlinearities on metal and composite airframe structures via intensity based health monitoring.

    PubMed

    Romano, P Q; Conlon, S C; Smith, E C

    2013-01-01

    Nonlinear structural intensity (NSI) and nonlinear structural surface intensity (NSSI) based damage detection techniques were improved and extended to metal and composite airframe structures. In this study, the measurement of NSI maps at sub-harmonic frequencies was completed to provide enhanced understanding of the energy flow characteristics associated with the damage induced contact acoustic nonlinearity mechanism. Important results include NSI source localization visualization at ultra-subharmonic (nf/2) frequencies, and damage detection results utilizing structural surface intensity in the nonlinear domain. A detection metric relying on modulated wave spectroscopy was developed and implemented using the NSSI feature. The data fusion of the intensity formulation provided a distinct advantage, as both the single interrogation frequency NSSI and its modulated wave extension (NSSI-MW) exhibited considerably higher sensitivities to damage than using single-sensor (strain or acceleration) nonlinear detection metrics. The active intensity based techniques were also extended to composite materials, and results show both NSSI and NSSI-MW can be used to detect damage in the bond line of an integrally stiffened composite plate structure with high sensitivity. Initial damage detection measurements made on an OH-58 tailboom (Penn State Applied Research Laboratory, State College, PA) indicate the techniques can be transitioned to complex airframe structures achieving high detection sensitivities with minimal sensors and actuators. PMID:23297894

  16. Monitoring of Refractory wall recession using radar technique

    SciTech Connect

    University of missouri

    2003-12-30

    Furnaces are the most crucial components in the glass and metallurgical industry. Like any other components in an industry, furnaces require periodic maintenance and repair. Today, furnaces are being operated at higher temperatures and for longer periods of time thus increasing the rate of wear and tear on the furnace refractory lining. As a result of the competitive market facing these industries, longer furnace lifetime with shorter maintenance downtime are increasingly required. Higher fuel consumption, low production and safety are issues that accompany delayed maintenance. Consequently, there is a need to know the state of a refractory wall to prevent premature or unnecessary maintenance shutdowns. For many years the observation skills of an experienced operator has been the primary source of evaluating the wear associated with a refractory wall. The rate of regression of a refractory lining depends on the type of the refractory lining, the materials Monitoring of Refractory Wall Recession Using Frequency-Modulated Continuous-Wave (FM-CW) Radar Techniques: A Proof-of-Concept Study, Final Report, Submitted to the Department of Energy (DOE), September 2003. being melted, seepage, mechanical stresses, and temperature. Moreover, the regression of a refractory lining is also not uniform throughout a furnace and it is more prominent at the metal line along the sidewalls as this region is exposed to hot gaseous byproducts and flowing molten material. Hence, more accurate measurement techniques are required to determine the local residual thickness of a refractory lining so as to utilize the refractory lining to the maximum extent possible. The use of isotope radiators, thermocouples and endoscopes has also been investigated for monitoring regression. These techniques are capable of providing scanned thermal images showing the profile of the refractory wall. However, these techniques can only provide relative profile information and cannot provide absolute thickness

  17. Use of acoustic velocity methodology and remote sensing techniques to measure unsteady flow on the lower Yazoo River in Mississippi

    USGS Publications Warehouse

    Turnipseed, D. Phil; Cooper, Lance M.; Davis, Angela A.

    1998-01-01

    Methodologies have been developed for computing continuous discharge during varied, non-uniform low and medium flows on the Yazoo River at the U.S. Geological Survey streamgage below Steele Bayou near Long Lake, Mississippi, using acoustic signal processing and conventional streamgaging techniques. Procedures were also developed to compute locations of discharges during future high flow events when the stream reach is subject to hi-directional and reverse flow caused by rising stages on the Mississippi River using a combination of acoustic equipment and remote sensing technology. A description of the study area is presented. Selected results of these methods are presented for the period from March through September 1997.

  18. A new monitoring technique for the grounding grids

    NASA Astrophysics Data System (ADS)

    Chikarov, Y.; Lie, T. T.; Nair, N.-K. C.

    2014-09-01

    The performance and reliability of grounding grids depend on its structural integrity. If grounding conductors are damaged, it may cause misoperation of protective relay which leads to trip feeders unnecessarily. It can also cause not only failures on the surroundings such as the grounding grid, secondary circuits' cables, and structural elements but also voltage hazard for human. The circuits may attain unacceptable voltages when short-circuit fault currents occur in these grids. This paper presents the development of a new technique to monitor the operating conditions of the grounding grids of high voltage apparatus and systems without any diggings and forced outages. New concept, principals, a technique and a device shown in the paper have never been described before by the other authors. The technique is based on the evaluation of the electromagnetic field distribution pattern over the damaged horizontal elements of the grid.

  19. Study Acoustic Emissions from Composites

    NASA Technical Reports Server (NTRS)

    Walker, James; Workman,Gary

    1998-01-01

    The purpose of this work will be to develop techniques for monitoring the acoustic emissions from carbon epoxy composite structures at cryogenic temperatures. Performance of transducers at temperatures ranging from ambient to cryogenic and the characteristics of acoustic emission from composite structures will be studied and documented. This entire effort is directed towards characterization of structures used in NASA propulsion programs such as the X-33.

  20. Size Distribution of Sperm Whales Acoustically Identified during Long Term Deep-Sea Monitoring in the Ionian Sea

    PubMed Central

    Caruso, Francesco; Sciacca, Virginia; Bellia, Giorgio; De Domenico, Emilio; Larosa, Giuseppina; Papale, Elena; Pellegrino, Carmelo; Pulvirenti, Sara; Riccobene, Giorgio; Simeone, Francesco; Speziale, Fabrizio; Viola, Salvatore; Pavan, Gianni

    2015-01-01

    The sperm whale (Physeter macrocephalus) emits a typical short acoustic signal, defined as a “click”, almost continuously while diving. It is produced in different time patterns to acoustically explore the environment and communicate with conspecifics. Each emitted click has a multi-pulse structure, resulting from the production of the sound within the sperm whale’s head. A Stable Inter Pulse Interval (Stable IPI) can be identified among the pulses that compose a single click. Applying specific algorithms, the measurement of this interval provides useful information to assess the total length of the animal recorded. In January 2005, a cabled hydrophone array was deployed at a depth of 2,100 m in the Central Mediterranean Sea, 25 km offshore Catania (Ionian Sea). The acoustic antenna, named OνDE (Ocean noise Detection Experiment), was in operation until November 2006. OνDE provided real time acoustic data used to perform Passive Acoustic Monitoring (PAM) of cetacean sound emissions. In this work, an innovative approach was applied to automatically measure the Stable IPI of the clicks, performing a cepstrum analysis to the energy (square amplitude) of the signals. About 2,100 five-minute recordings were processed to study the size distribution of the sperm whales detected during the OνDE long term deep-sea acoustic monitoring. Stable IPIs were measured in the range between 2.1 ms and 6.4 ms. The equations of Gordon (1991) and of Growcott (2011) were used to convert the IPIs into measures of size. The results revealed that the sperm whales recorded were distributed in length from about 7.5 m to 14 m. The size category most represented was from 9 m to 12 m (adult females or juvenile males) and specimens longer than 14 m (old males) seemed to be absent. PMID:26675588

  1. Size Distribution of Sperm Whales Acoustically Identified during Long Term Deep-Sea Monitoring in the Ionian Sea.

    PubMed

    Caruso, Francesco; Sciacca, Virginia; Bellia, Giorgio; De Domenico, Emilio; Larosa, Giuseppina; Papale, Elena; Pellegrino, Carmelo; Pulvirenti, Sara; Riccobene, Giorgio; Simeone, Francesco; Speziale, Fabrizio; Viola, Salvatore; Pavan, Gianni

    2015-01-01

    The sperm whale (Physeter macrocephalus) emits a typical short acoustic signal, defined as a "click", almost continuously while diving. It is produced in different time patterns to acoustically explore the environment and communicate with conspecifics. Each emitted click has a multi-pulse structure, resulting from the production of the sound within the sperm whale's head. A Stable Inter Pulse Interval (Stable IPI) can be identified among the pulses that compose a single click. Applying specific algorithms, the measurement of this interval provides useful information to assess the total length of the animal recorded. In January 2005, a cabled hydrophone array was deployed at a depth of 2,100 m in the Central Mediterranean Sea, 25 km offshore Catania (Ionian Sea). The acoustic antenna, named OνDE (Ocean noise Detection Experiment), was in operation until November 2006. OνDE provided real time acoustic data used to perform Passive Acoustic Monitoring (PAM) of cetacean sound emissions. In this work, an innovative approach was applied to automatically measure the Stable IPI of the clicks, performing a cepstrum analysis to the energy (square amplitude) of the signals. About 2,100 five-minute recordings were processed to study the size distribution of the sperm whales detected during the OνDE long term deep-sea acoustic monitoring. Stable IPIs were measured in the range between 2.1 ms and 6.4 ms. The equations of Gordon (1991) and of Growcott (2011) were used to convert the IPIs into measures of size. The results revealed that the sperm whales recorded were distributed in length from about 7.5 m to 14 m. The size category most represented was from 9 m to 12 m (adult females or juvenile males) and specimens longer than 14 m (old males) seemed to be absent.

  2. Size Distribution of Sperm Whales Acoustically Identified during Long Term Deep-Sea Monitoring in the Ionian Sea.

    PubMed

    Caruso, Francesco; Sciacca, Virginia; Bellia, Giorgio; De Domenico, Emilio; Larosa, Giuseppina; Papale, Elena; Pellegrino, Carmelo; Pulvirenti, Sara; Riccobene, Giorgio; Simeone, Francesco; Speziale, Fabrizio; Viola, Salvatore; Pavan, Gianni

    2015-01-01

    The sperm whale (Physeter macrocephalus) emits a typical short acoustic signal, defined as a "click", almost continuously while diving. It is produced in different time patterns to acoustically explore the environment and communicate with conspecifics. Each emitted click has a multi-pulse structure, resulting from the production of the sound within the sperm whale's head. A Stable Inter Pulse Interval (Stable IPI) can be identified among the pulses that compose a single click. Applying specific algorithms, the measurement of this interval provides useful information to assess the total length of the animal recorded. In January 2005, a cabled hydrophone array was deployed at a depth of 2,100 m in the Central Mediterranean Sea, 25 km offshore Catania (Ionian Sea). The acoustic antenna, named OνDE (Ocean noise Detection Experiment), was in operation until November 2006. OνDE provided real time acoustic data used to perform Passive Acoustic Monitoring (PAM) of cetacean sound emissions. In this work, an innovative approach was applied to automatically measure the Stable IPI of the clicks, performing a cepstrum analysis to the energy (square amplitude) of the signals. About 2,100 five-minute recordings were processed to study the size distribution of the sperm whales detected during the OνDE long term deep-sea acoustic monitoring. Stable IPIs were measured in the range between 2.1 ms and 6.4 ms. The equations of Gordon (1991) and of Growcott (2011) were used to convert the IPIs into measures of size. The results revealed that the sperm whales recorded were distributed in length from about 7.5 m to 14 m. The size category most represented was from 9 m to 12 m (adult females or juvenile males) and specimens longer than 14 m (old males) seemed to be absent. PMID:26675588

  3. Measuring acoustic habitats

    PubMed Central

    Merchant, Nathan D; Fristrup, Kurt M; Johnson, Mark P; Tyack, Peter L; Witt, Matthew J; Blondel, Philippe; Parks, Susan E

    2015-01-01

    1. Many organisms depend on sound for communication, predator/prey detection and navigation. The acoustic environment can therefore play an important role in ecosystem dynamics and evolution. A growing number of studies are documenting acoustic habitats and their influences on animal development, behaviour, physiology and spatial ecology, which has led to increasing demand for passive acoustic monitoring (PAM) expertise in the life sciences. However, as yet, there has been no synthesis of data processing methods for acoustic habitat monitoring, which presents an unnecessary obstacle to would-be PAM analysts. 2. Here, we review the signal processing techniques needed to produce calibrated measurements of terrestrial and aquatic acoustic habitats. We include a supplemental tutorial and template computer codes in matlab and r, which give detailed guidance on how to produce calibrated spectrograms and statistical analyses of sound levels. Key metrics and terminology for the characterisation of biotic, abiotic and anthropogenic sound are covered, and their application to relevant monitoring scenarios is illustrated through example data sets. To inform study design and hardware selection, we also include an up-to-date overview of terrestrial and aquatic PAM instruments. 3. Monitoring of acoustic habitats at large spatiotemporal scales is becoming possible through recent advances in PAM technology. This will enhance our understanding of the role of sound in the spatial ecology of acoustically sensitive species and inform spatial planning to mitigate the rising influence of anthropogenic noise in these ecosystems. As we demonstrate in this work, progress in these areas will depend upon the application of consistent and appropriate PAM methodologies. PMID:25954500

  4. Autonomous hydrophone array for long-term acoustic monitoring in the open ocean

    NASA Astrophysics Data System (ADS)

    D'Eu, J.-F.; Brachet, C.; Goslin, J.; Royer, J.-Y.; Ammann, J.

    2009-04-01

    We are developing an array of new autonomous hydrophones, benefiting from a long-lasting collaboration with the Pacific Marine Environmental Laboratory (NOAA and Oregon state University). The hydrophones are deployed on a mooring line anchored to the seafloor by an expendable anchor weight. The length of the line is adjusted so that the sensor (and buoy) lies in the middle of the SOFAR channel at about 1000m depth for mid-latitudes (depending on the speed-of-sound profile). The buoy at depth keeps the line under tension and prevents wave-motion noise from the sensor. The instrument continuously samples and records the acoustic signals at 240Hz for seismic studies, or 480Hz (or more) for marine mammal studies. The SOFAR channel acts as an acoustic wave-guide in the ocean so that acoustic waves can propagate with little attenuation over long distances. Autonomous hydrophones allow the detection and localization of the low-magnitude (Mw>2.5) seismic activity along oceanic ridges and in deformed intraplate areas, which remains generally undetected or poorly localized by land-based seismic networks. An array of hydrophones can monitor a much wider area (more than 1000 km across) than ocean-bottom seismometers, which suffer from the rapid attenuation of seismic waves in the crust and upper mantle. Arrays of autonomous hydrophones thus succeed in detecting and locating 30 to 50 times more earthquakes than those listed in the catalogs from land-based seismograph stations. Data are buffered on flash cards and then regularly stored on hard disks or on solid-state drives (e.g. 20Gb of data per year at 240Hz sampling rate). We use 24-bit sigma-delta converters with programmable gain amplifiers. As timing is a key issue for an accurate localisation of the seismic events, instruments are synchronized with GPS time and have a low-power, highly stable calibrated clock (10-8 drift). All electronics and batteries (Li or alcaline) are placed in titanium pressure cases for long

  5. ASSESSMENT OF CABLE AGING USING CONDITION MONITORING TECHNIQUES

    SciTech Connect

    GROVE,E.; LOFARO,R.; SOO,P.; VILLARAN,M.; HSU,F.

    2000-04-06

    Electric cables in nuclear power plants suffer degradation during service as a result of the thermal and radiation environments in which they are installed. Instrumentation and control cables are one type of cable that provide an important role in reactor safety. Should the polymeric cable insulation material become embrittled and cracked during service, or during a loss-of-coolant-accident (LOCA) and when steam and high radiation conditions are anticipated, failure could occur and prevent the cables from fulfilling their intended safety function(s). A research program is being conducted at Brookhaven National Laboratory to evaluate condition monitoring (CM) techniques for estimating the amount of cable degradation experienced during in-plant service. The objectives of this program are to assess the ability of the cables to perform under a simulated LOCA without losing their ability to function effectively, and to identify CM techniques which may be used to determine the effective lifetime of cables. The cable insulation materials tested include ethylene propylene rubber (EPR) and cross-linked polyethylene (XLPE). Accelerated aging (thermal and radiation) to the equivalent of 40 years of service was performed, followed by exposure to simulated LOCA conditions. The effectiveness of chemical, electrical, and mechanical condition monitoring techniques are being evaluated. Results indicate that several of these methods can detect changes in material parameters with increasing age. However, each has its limitations, and a combination of methods may provide an effective means for trending cable degradation in order to assess the remaining life of cables.

  6. Reflection of no equilibrium two Phase Processes of Filtration in heterogeneous Media in the active seism acoustic borehole monitoring Data

    NASA Astrophysics Data System (ADS)

    Hachay, Olga; Dryagin, Veniamin; Igolkina, Galina; Khachay, Oleg

    2013-04-01

    It is provided a comparison of no equilibrium effects by independent hydro dynamical and seism acoustic influence on an oil layer. It is known, that by drainage and steeps the hysteresis effect on curves of the relative phase permeability in dependence from porous medium water saturation by some cycles of influence: drainage-steep-drainage is observed. In earlier papers the analysis of the seism acoustic monitoring data in regimes of phone radiation, response on the first influence of given frequency and on the second influence is developed. For the analysis of seism acoustic response in time on fixed intervals along the borehole an algorithm of phase diagrams of the state of many phase medium is suggested In that paper on the base of developed algorithm a new algorithm of analyze of space, but integral in time for equal observation periods changing by the method of phase diagram state of many phase medium in the oil layer is developed. The paper was supported by the Program of Presidium UB RAS 2012-2014. Key words: Oil and gas deposits, seism acoustic borehole monitoring data, new method of processing, reflection of no equilibrium two phase processes, heterogeneous media.

  7. Analysis of ultrasonic techniques for monitoring milk coagulation during cheesemaking

    NASA Astrophysics Data System (ADS)

    Budelli, E.; Pérez, N.; Lema, P.; Negreira, C.

    2012-12-01

    Experimental determination of time of flight and attenuation has been proposed in the literature as alternatives to monitoring the evolution of milk coagulation during cheese manufacturing. However, only laboratory scale procedures have been described. In this work, the use of ultrasonic time of flight and attenuation to determine cutting time and its feasibility to be applied at industrial scale were analyzed. Limitations to implement these techniques at industrial scale are shown experimentally. The main limitation of the use of time of flight is its strong dependence with temperature. Attenuation monitoring is affected by a thin layer of milk skin covering the transducer, which modifies the signal in a non-repetitive way. The results of this work can be used to develop alternative ultrasonic systems suitable for application in the dairy industry.

  8. An integrated sensing technique for smart monitoring of water pipelines

    NASA Astrophysics Data System (ADS)

    Bernini, Romeo; Catapano, Ilaria; Soldovieri, Francesco; Crocco, Lorenzo

    2014-05-01

    Lowering the rate of water leakage from the network of underground pipes is one of the requirements that "smart" cities have to comply with. In fact, losses in the water supply infrastructure have a remarkable social, environmental and economic impact, which obviously conflicts with the expected efficiency and sustainability of a smart city. As a consequence, there is a huge interest in developing prevention policies based on state-of-art sensing techniques and possibly their integration, as well as in envisaging ad hoc technical solutions designed for the application at hand. As a contribution to this framework, in this communication we present an approach aimed to pursue a thorough non-invasive monitoring of water pipelines, with both high spatial and temporal resolution. This goal is necessary to guarantee that maintenance operations are performed timely, so to reduce the extent of the leakage and its possible side effects, and precisely, so to minimize the cost and the discomfort resulting from operating on the water supply network. The proposed approach integrates two sensing techniques that work at different spatial and temporal scales. The first one is meant to provide a continuous (in both space and time) monitoring of the pipeline and exploits a distributed optic fiber sensor based on the Brillouin scattering phenomenon. This technique provides the "low" spatial resolution information (at meter scale) needed to reveal the presence of a leak and call for interventions [1]. The second technique is based on the use of Ground Penetrating Radar (GPR) and is meant to provide detailed images of area where the damage has been detected. GPR systems equipped with suitable data processing strategies [2,3] are indeed capable of providing images of the shallow underground, where the pipes would be buried, characterized by a spatial resolution in the order of a few centimeters. This capability is crucial to address in the most proper way maintenance operations, by for

  9. Feasibility Study for Monitoring Oil Recovery Using Full Waveform Acoustic Logs in Eastern Venezuela

    NASA Astrophysics Data System (ADS)

    Floricich, M.; Perez, E.; Mendoza, J.

    2001-12-01

    Feasibility study for monitoring fluid flow through a reservoir can serve as a tool to understand how changes in fluids saturation, pressures and/or temperatures during production phase alter the elastic parameters of reservoir rocks. Those changes may be detected via seismic records at several production time windows. Previous works on this area involve measuring well cores elastics properties in the lab, limiting the method where core data is available. In this study, full waveform acoustic logs have been used to compute elastic properties of reservoir rocks. The use of this kind of log produces a more abundant set of elastic parameters over a broader depth interval, which better represents real conditions of the reservoir. Those data along with the fluid flow simulation model, were used to construct maps for the elastic properties in saturated media, via Gassman relationships and Biot theory. The methodology has been applied to the Santa Barbara field located at eastern Venezuela. The Santa Barbara field is a gas and oil productive field. The results have been compared favorably to those obtained in a previous work using only well core data

  10. Automatic Detection of Swallowing Events by Acoustical Means for Applications of Monitoring of Ingestive Behavior

    PubMed Central

    Sazonov, Edward S.; Makeyev, Oleksandr; Schuckers, Stephanie; Lopez-Meyer, Paulo; Melanson, Edward L.; Neuman, Michael R.

    2010-01-01

    Our understanding of etiology of obesity and overweight is incomplete due to lack of objective and accurate methods for Monitoring of Ingestive Behavior (MIB) in the free living population. Our research has shown that frequency of swallowing may serve as a predictor for detecting food intake, differentiating liquids and solids, and estimating ingested mass. This paper proposes and compares two methods of acoustical swallowing detection from sounds contaminated by motion artifacts, speech and external noise. Methods based on mel-scale Fourier spectrum, wavelet packets, and support vector machines are studied considering the effects of epoch size, level of decomposition and lagging on classification accuracy. The methodology was tested on a large dataset (64.5 hours with a total of 9,966 swallows) collected from 20 human subjects with various degrees of adiposity. Average weighted epoch recognition accuracy for intra-visit individual models was 96.8% which resulted in 84.7% average weighted accuracy in detection of swallowing events. These results suggest high efficiency of the proposed methodology in separation of swallowing sounds from artifacts that originate from respiration, intrinsic speech, head movements, food ingestion, and ambient noise. The recognition accuracy was not related to body mass index, suggesting that the methodology is suitable for obese individuals. PMID:19789095

  11. Acoustic emission-based sensor analysis and damage classification for structural health monitoring of composite structures

    NASA Astrophysics Data System (ADS)

    Uprety, Bibhisha

    Within the aerospace industry the need to detect and locate impact events, even when no visible damage is present, is important both from the maintenance and design perspectives. This research focused on the use of Acoustic Emission (AE) based sensing technologies to identify impact events and characterize damage modes in composite structures for structural health monitoring. Six commercially available piezoelectric AE sensors were evaluated for use with impact location estimation algorithms under development at the University of Utah. Both active and passive testing were performed to estimate the time of arrival and plate wave mode velocities for impact location estimation. Four sensors were recommended for further comparative investigations. Furthermore, instrumented low-velocity impact experiments were conducted on quasi-isotropic carbon/epoxy composite laminates to initiate specific types of damage: matrix cracking, delamination and fiber breakage. AE signal responses were collected during impacting and the test panels were ultrasonically C-scanned after impact to identify the internal damage corresponding to the AE signals. Matrix cracking and delamination damage produced using more compliant test panels and larger diameter impactor were characterized by lower frequency signals while fiber breakage produced higher frequency responses. The results obtained suggest that selected characteristics of sensor response signals can be used both to determine whether damage is produced during impacting and to characterize the types of damage produced in an impacted composite structure.

  12. A novel acoustic emission monitoring and signal processing to elucidate the fracture dynamics of hydrogen assisted cracking

    SciTech Connect

    Hayashi, Yasuhisa; Takemoto, Makoto; Takemoto, Mikio

    1994-12-31

    An advanced Acoustic Emission (AE) monitoring and signal processing system was developed and applied to elucidate the fracture dynamics of hydrogen assisted cracking (HAC) of quenched-tempered low alloy steel. The developed system enables one to monitor an initiation of microcrack correctly and also to elucidate the dynamics of microcracks when multi-channel moment tensor analysis is jointly used. The system consists of 8-channel monitoring. One channel monitors the surface displacement in loading direction excited by the propagation of elastic wave, and gives the source wave by the deconvolution integral of it with the Green`s function of the second kind. Another 7 channels were designed to measure arrival time and relative amplitude of the P-waves, and to determine both the source location and the crack kinematics by tensor analysis. This paper introduces the developed monitoring system and signal processing method, and fracture dynamics of microcracks in HAC.

  13. Modeling of the Acoustic Reverberation Special Research Program deep ocean seafloor scattering experiments using a hybrid wave propagation simulation technique

    NASA Astrophysics Data System (ADS)

    Robertsson, Johan O. A.; Levander, Alan; Holliger, Klaus

    1996-02-01

    Quantitative modeling of bottom-interacting ocean acoustic waves is complicated by the long propagation ranges and by the complexity of the scattering targets. We employ a two-dimensional (2-D) hybrid technique combining Gaussian beam, finite difference, and Kirchhoff integral solutions of the wave equation to simulate ocean acoustic experiments within half of a convergence zone in the SOFAR channel. The 2-D modeling approach is reasonable due to the one-dimensional (1-D) velocity distribution in the water column and the strong lineation of the seafloor morphology parallel to the mid-ocean ridges. Full-waveform modeling of ocean acoustic data requires that the topography and the material properties of the seafloor are available at scales that are several orders of magnitude smaller than typical bathymetric sampling rates. We have therefore investigated the effects on the ocean acoustic response of a stochastic interpolation scheme used to generate seafloor models. For typical grazing angles of the incident wave field (approximately 5°-20°), we found that different stochastic realizations of the same seafloor segment (sampled at 200 m) yield an intrinsic uncertainty of the order of 3-8 dB in amplitude and 0.1-0.3 s in time for individual prominent events in the reverberant acoustic field. Hybrid simulations are compared to beam-formed ocean acoustic data collected during the Acoustic Reverberation Special Research Program (ARSRP) cruises. Side lobe noise in the observed acoustic data is simulated by adding band-limited white noise at -30 dB relative to the maximum intensity in the synthetic data. Numerical simulations can be limited to the response of only one of the mirror azimuth beams provided that the experimental geometry is suitably chosen. For the 2-D approximation to be valid, the cross-range resolution of the observed data must be smaller than the characteristic scale of seafloor lineations, and the beams of interest must be approximately perpendicular to

  14. Acoustic Monitoring System for Frog Population Estimation Using In-Situ Progressive Learning

    NASA Astrophysics Data System (ADS)

    Aboudan, Adam

    Frog populations are considered excellent bio-indicators and hence the ability to monitor changes in their populations can be very useful for ecological research and environmental monitoring. This thesis presents a new population estimation approach based on the recognition of individual frogs of the same species, namely the Pseudacris Regilla (Pacific Chorus Frog), which does not rely on the availability of prior training data. An in-situ progressive learning algorithm is developed to determine whether an incoming call belongs to a previously detected individual frog or a newly encountered individual frog. A temporal call overlap detector is also presented as a pre-processing tool to eliminate overlapping calls. This is done to prevent the degrading of the learning process. The approach uses Mel-frequency cepstral coefficients (MFCCs) and multivariate Gaussian models to achieve individual frog recognition. In the first part of this thesis, the MFCC as well as the related linear predictive cepstral coefficients (LPCC) acoustic feature extraction processes are reviewed. The Gaussian mixture models (GMM) are also reviewed as an extension to the classical Gaussian modeling used in the proposed approach. In the second part of this thesis, the proposed frog population estimation system is presented and discussed in detail. The proposed system involves several different components including call segmentation, feature extraction, overlap detection, and the in-situ progressive learning process. In the third part of the thesis, data description and system performance results are provided. The process of synthetically generating test sequences of real frog calls, which are applied to the proposed system for performance analysis, is described. Also, the results of the system performance are presented which show that the system is successful in distinguishing individual frogs, hence capable of providing reasonable estimates of the frog population. The system can readily be

  15. Fatigue crack growth monitoring of idealized gearbox spline component using acoustic emission

    NASA Astrophysics Data System (ADS)

    Zhang, Lu; Ozevin, Didem; Hardman, William; Kessler, Seth; Timmons, Alan

    2016-04-01

    The spline component of gearbox structure is a non-redundant element that requires early detection of flaws for preventing catastrophic failures. The acoustic emission (AE) method is a direct way of detecting active flaws; however, the method suffers from the influence of background noise and location/sensor based pattern recognition method. It is important to identify the source mechanism and adapt it to different test conditions and sensors. In this paper, the fatigue crack growth of a notched and flattened gearbox spline component is monitored using the AE method in a laboratory environment. The test sample has the major details of the spline component on a flattened geometry. The AE data is continuously collected together with strain gauges strategically positions on the structure. The fatigue test characteristics are 4 Hz frequency and 0.1 as the ratio of minimum to maximum loading in tensile regime. It is observed that there are significant amount of continuous emissions released from the notch tip due to the formation of plastic deformation and slow crack growth. The frequency spectra of continuous emissions and burst emissions are compared to understand the difference of sudden crack growth and gradual crack growth. The predicted crack growth rate is compared with the AE data using the cumulative AE events at the notch tip. The source mechanism of sudden crack growth is obtained solving the inverse mathematical problem from output signal to input signal. The spline component of gearbox structure is a non-redundant element that requires early detection of flaws for preventing catastrophic failures. In this paper, the fatigue crack growth of a notched and flattened gearbox spline component is monitored using the AE method The AE data is continuously collected together with strain gauges. There are significant amount of continuous emissions released from the notch tip due to the formation of plastic deformation and slow crack growth. The source mechanism of

  16. Detection of bond failure in the anchorage zone of reinforced concrete beams via acoustic emission monitoring

    NASA Astrophysics Data System (ADS)

    Abouhussien, Ahmed A.; Hassan, Assem A. A.

    2016-07-01

    In this study, acoustic emission (AE) monitoring was utilised to identify the onset of bond failure in reinforced concrete beams. Beam anchorage specimens were designed and tested to fail in bond in the anchorage zone. The specimens included four 250 × 250 × 1500 mm beams with four variable bonded lengths (100, 200, 300, and 400 mm). Meanwhile, an additional 250 × 250 × 2440 mm beam, with 200 mm bonded length, was tested to investigate the influence of sensor location on the identification of bond damage. All beams were tested under four-point loading setup and continuously monitored using three distributed AE sensors. These attached sensors were exploited to record AE signals resulting from both cracking and bond deterioration until failure. The variations in the number of AE hits and cumulative signal strength (CSS) versus test time were evaluated to achieve early detection of crack growth and bar slippage. In addition, AE intensity analysis was performed on signal strength of collected AE signals to develop two additional parameters: historic index (H (t)) and severity (S r). The analysis of these AE parameters enabled an early detection of both first cracks (at almost the mid-span of the beam) and bar slip in either of the anchorage zones at the beams’ end before their visual observation, regardless of sensor location. The results also demonstrated a clear correlation between the damage level in terms of crack development/measured free end bar slip and AE parameters (number of hits, CSS, H(t), and S r).

  17. Monitoring of Lactic Fermentation Process by Ultrasonic Technique

    NASA Astrophysics Data System (ADS)

    Alouache, B.; Touat, A.; Boutkedjirt, T.; Bennamane, A.

    The non-destructive control by using ultrasound techniques has become of great importance in food industry. In this work, Ultrasound has been used for quality control and monitoring the fermentation stages of yogurt, which is a highly consumed product. On the contrary to the physico-chemical methods, where the measurement instruments are directly introduced in the sample, ultrasound techniques have the advantage of being non-destructive and contactless, thus reducing the risk of contamination. Results obtained in this study by using ultrasound seem to be in good agreement with those obtained by physico-chemical methods such as acidity measurement by using a PH-meter instrument. This lets us to conclude that ultrasound method may be an alternative for a healthy control of yoghurt fermentation process.

  18. Integration of Field and Remote Sensing Techniques For Landslides Monitoring

    NASA Astrophysics Data System (ADS)

    Allievi, J.; Ambrosi, C.; Ceriani, M.; Colesanti, C.; Crosta, G. B.; Ferretti, A.; Fossati, D.; Menegaz, A.

    The definition of the state of activity of slope movements is of major interest both at local and at regional scale. The Geological Survey of the Regione Lombardia has re- cently started a series of projects aimed to the identification of areas subjected to slope instability and to the assessment of their state of activity. Field survey, aerial photo interpretation and advanced remote sensing techniques have been applied. Some ex- amples of large rock slope instabilities have been investigated in the Valtellina area (Lombardia, Northern Italy). In particular, we demonstrate the degree of integration of the adopted techniques for one of the largest rock slope movements actually recog- nised in the area. The remote sensing approach that has been adopted is the Perma- nent Scatterers (PS) Technique. This technique has been recently developed as a new methodology for surface deformation monitoring, using ESA ERS-SAR data. Its ap- plication to large slope movements in alpine and prealpine areas, with a relatively low urban development, has been tried for the first time in order to evaluate its potential in supporting studies for landslide hazard assessment. Previous results show that this ap- proach allows to reach an accuracy very close to the theoretical limit. This study shows the very good agreement reached for displacement velocities between historical trends and recent PS measurements. Scatterers have been identified by field surveying and some of them are located close to historically monitored benchmark for topographic measurements. Furthermore, the integration of these data with field observations al- lowed us to perform a preliminary reconstrucion of the landslide mechanism and to assess the activity of different landslide structures (scarps, etc.).

  19. Passive Acoustic Monitoring of the Environmental Impact of Oil Exploration on Marine Mammals in the Gulf of Mexico.

    PubMed

    Sidorovskaia, Natalia A; Ackleh, Azmy S; Tiemann, Christopher O; Ma, Baoling; Ioup, Juliette W; Ioup, George E

    2016-01-01

    The Gulf of Mexico is a region densely populated by marine mammals that must adapt to living in a highly active industrial environment. This paper presents a new approach to quantifying the anthropogenic impact on the marine mammal population. The results for sperm and beaked whales of a case study of regional population dynamics trends after the Deepwater Horizon oil spill, derived from passive acoustic-monitoring data gathered before and after the spill in the vicinity of the accident, are presented.

  20. Acoustic mode measurements in the inlet of a model turbofan using a continuously rotating rake - Data collection/analysis techniques

    NASA Technical Reports Server (NTRS)

    Hall, David G.; Heidelberg, Laurence; Konno, Kevin

    1993-01-01

    The rotating microphone measurement technique and data analysis procedures are documented which are used to determine circumferential and radial acoustic mode content in the inlet of the Advanced Ducted Propeller (ADP) model. Circumferential acoustic mode levels were measured at a series of radial locations using the Doppler frequency shift produced by a rotating inlet microphone probe. Radial mode content was then computed using a least squares curve fit with the measured radial distribution for each circumferential mode. The rotating microphone technique is superior to fixed-probe techniques because it results in minimal interference with the acoustic modes generated by rotor-stator interaction. This effort represents the first experimental implementation of a measuring technique developed by T. G. Sofrin. Testing was performed in the NASA Lewis Low Speed Anechoic Wind Tunnel at a simulated takeoff condition of Mach 0.2. The design is included of the data analysis software and the performance of the rotating rake apparatus. The effect of experiment errors is also discussed.

  1. Acoustic mode measurements in the inlet of a model turbofan using a continuously rotating rake: Data collection/analysis techniques

    NASA Technical Reports Server (NTRS)

    Hall, David G.; Heidelberg, Laurence; Konno, Kevin

    1993-01-01

    The rotating microphone measurement technique and data analysis procedures are documented which are used to determine circumferential and radial acoustic mode content in the inlet of the Advanced Ducted Propeller (ADP) model. Circumferential acoustic mode levels were measured at a series of radial locations using the Doppler frequency shift produced by a rotating inlet microphone probe. Radial mode content was then computed using a least squares curve fit with the measured radial distribution for each circumferential mode. The rotating microphone technique is superior to fixed-probe techniques because it results in minimal interference with the acoustic modes generated by rotor-stator interaction. This effort represents the first experimental implementation of a measuring technique developed by T. G. Sofrin. Testing was performed in the NASA Lewis Low Speed Anechoic Wind Tunnel at a simulated takeoff condition of Mach 0.2. The design is included of the data analysis software and the performance of the rotating rake apparatus. The effect of experiment errors is also discussed.

  2. Monitoring a quarry using high resolution data and GIS techniques

    NASA Astrophysics Data System (ADS)

    Nikolakopoulos, Konstantinos G.; Tsombos, P. I.; Vaiopoulos, A. D.

    2010-10-01

    Active quarries near to urban centers are at the same time a necessity but also a source of pollution. Necessity as they supply to the construction companies the necessary aggregates and source of pollution as they affect biodiversity, vegetation cover and threaten water resources. The objective of this work is to indicate a monitoring methodology in order to survey the present state of the quarry sites and their evolution in time, which are the basic data needed to implement an adequate land reclamation project. The land monitoring has been realised both by using remote sensing techniques, supported by a Geographic Information System of the studied area, and by in situ surveying. The in situ surveying was able to assess the capability of the remote sensing model to describe the state of each site. High resolution satellite data from different sensors were used for the monitoring of an active quarry. More especially, Ikonos Quickbird, and Worldiew data were orthorectified and inserted in a GIS database in order to quantify the changes.

  3. Development of structural health monitoring techniques using dynamics testing

    SciTech Connect

    James, G.H. III

    1996-03-01

    Today`s society depends upon many structures (such as aircraft, bridges, wind turbines, offshore platforms, buildings, and nuclear weapons) which are nearing the end of their design lifetime. Since these structures cannot be economically replaced, techniques for structural health monitoring must be developed and implemented. Modal and structural dynamics measurements hold promise for the global non-destructive inspection of a variety of structures since surface measurements of a vibrating structure can provide information about the health of the internal members without costly (or impossible) dismantling of the structure. In order to develop structural health monitoring for application to operational structures, developments in four areas have been undertaken within this project: operational evaluation, diagnostic measurements, information condensation, and damage identification. The developments in each of these four aspects of structural health monitoring have been exercised on a broad range of experimental data. This experimental data has been extracted from structures from several application areas which include aging aircraft, wind energy, aging bridges, offshore structures, structural supports, and mechanical parts. As a result of these advances, Sandia National Laboratories is in a position to perform further advanced development, operational implementation, and technical consulting for a broad class of the nation`s aging infrastructure problems.

  4. Electrical Resistance Technique to Monitor SiC Composite Detection

    NASA Technical Reports Server (NTRS)

    Smith, Craig; Morscher, Gregory; Xia, Zhenhai

    2008-01-01

    Ceramic matrix composites are suitable for high temperature structural applications such as turbine airfoils and hypersonic thermal protection systems. The employment of these materials in such applications is limited by the ability to process components reliable and to accurately monitor and predict damage evolution that leads to failure under stressed-oxidation conditions. Current nondestructive methods such as ultrasound, x-ray, and thermal imaging are limited in their ability to quantify small scale, transverse, in-plane, matrix cracks developed over long-time creep and fatigue conditions. Electrical resistance of SiC/SiC composites is one technique that shows special promise towards this end. Since both the matrix and the fibers are conductive, changes in matrix or fiber properties should relate to changes in electrical conductivity along the length of a specimen or part. The effect of matrix cracking on electrical resistivity for several composite systems will be presented and some initial measurements performed at elevated temperatures under stress-rupture conditions. The implications towards electrical resistance as a technique applied to composite processing, damage detection (health monitoring), and life-modeling will be discussed.

  5. Wetland assessment, monitoring and management in India using geospatial techniques.

    PubMed

    Garg, J K

    2015-01-15

    Satellite remote sensing and GIS have emerged as the most powerful tools for inventorying, monitoring and management of natural resources and environment. In the special context of wetland ecosystems, remotely sensed data from orbital platforms have been extensively used in India for the inventory, monitoring and preparation of action plans for conservation and management. First scientific inventory of wetlands in India was carried out in 1998 by Space Applications Centre (ISRO), Ahmedabad using indigenous IRS (Indian Remote Sensing Satellite) data of 1992-93 timeframe, which stimulated extensive use of geospatial techniques for wetland conservation and management. Subsequently, with advances in GIS, studies were carried out for development of Wetland Information System for a state (West Bengal) and for Loktak lake wetland (a Ramsar site) as a prelude to National Wetland Information System. Research has also been carried out for preparation of action plans especially for Ramsar sites in the country. In a novel research, use of the geospatial technology has also been demonstrated for biodiversity conservation using landscape ecological metrics. A country-wide estimate of emission of methane, a Green House Gas, from wetlands has also been made using MODIS data. Present article critically reviews the work carried out in India for wetland conservation and management using geospatial techniques.

  6. Nonlinear Ultrasonic Techniques to Monitor Radiation Damage in RPV and Internal Components

    SciTech Connect

    Jacobs, Laurence; Kim, Jin-Yeon; Qu, Jisnmin; Ramuhalli, Pradeep; Wall, Joe

    2015-11-02

    The objective of this research is to demonstrate that nonlinear ultrasonics (NLU) can be used to directly and quantitatively measure the remaining life in radiation damaged reactor pressure vessel (RPV) and internal components. Specific damage types to be monitored are irradiation embrittlement and irradiation assisted stress corrosion cracking (IASCC). Our vision is to develop a technique that allows operators to assess damage by making a limited number of NLU measurements in strategically selected critical reactor components during regularly scheduled outages. This measured data can then be used to determine the current condition of these key components, from which remaining useful life can be predicted. Methods to unambiguously characterize radiation related damage in reactor internals and RPVs remain elusive. NLU technology has demonstrated great potential to be used as a material sensor – a sensor that can continuously monitor a material’s damage state. The physical effect being monitored by NLU is the generation of higher harmonic frequencies in an initially monochromatic ultrasonic wave. The degree of nonlinearity is quantified with the acoustic nonlinearity parameter, β, which is an absolute, measurable material constant. Recent research has demonstrated that nonlinear ultrasound can be used to characterize material state and changes in microscale characteristics such as internal stress states, precipitate formation and dislocation densities. Radiation damage reduces the fracture toughness of RPV steels and internals, and can leave them susceptible to IASCC, which may in turn limit the lifetimes of some operating reactors. The ability to characterize radiation damage in the RPV and internals will enable nuclear operators to set operation time thresholds for vessels and prescribe and schedule replacement activities for core internals. Such a capability will allow a more clear definition of reactor safety margins. The research consists of three tasks: (1

  7. Systems and methods of monitoring acoustic pressure to detect a flame condition in a gas turbine

    DOEpatents

    Ziminsky, Willy Steve; Krull, Anthony Wayne; Healy, Timothy Andrew , Yilmaz, Ertan

    2011-05-17

    A method may detect a flashback condition in a fuel nozzle of a combustor. The method may include obtaining a current acoustic pressure signal from the combustor, analyzing the current acoustic pressure signal to determine current operating frequency information for the combustor, and indicating that the flashback condition exists based at least in part on the current operating frequency information.

  8. Monitoring Induced Seismicity with Acoustic-Emission Sensors : The Calibration Problem

    NASA Astrophysics Data System (ADS)

    Plenkers, K.; Kwiatek, G.

    2012-12-01

    We study the effect that an uncalibrated acoustic-emission (AE) sensor has on source parameters using data of the JAGUARS project. The JAGUARS project recorded mining-induced seismicity in Mponeng Gold mine in Carletonville, South Africa in the frequency range 1 kHz < f < 180 kHz combining AE-sensors and accelerometers. Advanced monitoring of induced seismicity in underground structures sometimes includes today the use of high-frequency (f >> 1 kHz) AE monitoring systems. High-frequency monitoring allows the detection of seismic fractures on the centimeter scale and provides therefore important information about the migration of instabilities in the rock. Whereas the temporal-spatial analysis of seismic events recorded with AE sensors provides stable results, the analysis of source parameters including the estimation of magnitudes remains more challenging, because AE sensors are normally not well calibrated and exploit resonance frequencies to allow for high sensitivity. In our study the AE sensors are first calibrated in the frequency range 1kHz to 17 kHz relative to the well calibrated accelerometer. The calibration is possible due to the close employment of both sensor types, which allows to extract the sensor response (including the coupling effect) using signal deconvolution. We estimate three main resonance frequencies at about 2.5 kHz, 6 kHz and 10 kHz. Furthermore we calculate the directivity effect of the AE-sensor that influences the amplitude of the signal by up to - 15 dB. Second, we calculate the effect of the instrument response on the calculation of magnitude, magnitude-frequency distribution and static source parameters. We study magnitudes, magitude-frequency distributions and static source parameters using both the calibrated sensors, as well as the uncalibrated AE sensors. We show the significant uncertainty that is indroduced owing to the AE sensor response and conclude that source parameters often have high uncertainties and are not reliable

  9. Effect of monitoring technique on quality of conservation science.

    PubMed

    Jewell, Zoe

    2013-06-01

    Monitoring free-ranging animals in their natural habitat is a keystone of ecosystem conservation and increasingly important in the context of current rates of loss of biological diversity. Data collected from individuals of endangered species inform conservation policies. Conservation professionals assume that these data are reliable-that the animals from whom data are collected are representative of the species in their physiology, ecology, and behavior and of the populations from which they are drawn. In the last few decades, there has been an enthusiastic adoption of invasive techniques for gathering ecological and conservation data. Although these can provide impressive quantities of data, and apparent insights into animal ranges and distributions, there is increasing evidence that these techniques can result in animal welfare problems, through the wide-ranging physiological effects of acute and chronic stress and through direct or indirect injuries or compromised movement. Much less commonly, however, do conservation scientists consider the issue of how these effects may alter the behavior of individuals to the extent that the data they collect could be unreliable. The emerging literature on the immediate and longer-term effects of capture and handling indicate it can no longer be assumed that a wild animal's survival of the process implies the safety of the procedure, that the procedure is ethical, or the scientific validity of the resulting data. I argue that conservation professionals should routinely assess study populations for negative effects of their monitoring techniques and adopt noninvasive approaches for best outcomes not only for the animals, but also for conservation science.

  10. Acoustic Emission Technique for Characterizing Deformation and Fatigue Crack Growth in Austenitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Raj, Baldev; Mukhopadhyay, C. K.; Jayakumar, T.

    2003-03-01

    Acoustic emission (AE) during tensile deformation and fatigue crack growth (FCG) of austenitic stainless steels has been studied. In AISI type 316 stainless steel (SS), AE has been used to detect micro plastic yielding occurring during macroscopic plastic deformation. In AISI type 304 SS, relation of AE with stress intensity factor and plastic zone size has been studied. In AISI type 316 SS, fatigue crack growth has been characterised using acoustic emission.

  11. Robust satellite techniques for oil spill detection and monitoring

    NASA Astrophysics Data System (ADS)

    Casciello, D.; Pergola, N.; Tramutoli, V.

    Discharge of oil into the sea is one of the most dangerous, among technological hazards, for the maritime environment. In the last years maritime transport and exploitation of marine resources continued to increase; as a result, tanker accidents are nowadays increasingly frequent, continuously menacing the maritime security and safety. Satellite remote sensing could contribute in multiple ways, in particular for what concerns early warning and real-time (or near real-time) monitoring. Several satellite techniques exist, mainly based on the use of SAR (Synthetic Aperture Radar) technology, which are able to recognise, with sufficient accuracy, oil spills discharged into the sea. Unfortunately, such methods cannot be profitably used for real-time detection, because of the low observational frequency assured by present satellite platforms carrying SAR sensors (the mean repetition rate is something like 30 days). On the other hand, potential of optical sensors aboard meteorological satellites, was not yet fully exploited and no reliable techniques have been developed until now for this purpose. Main limit of proposed techniques can be found in the ``fixed threshold'' approach which makes such techniques difficult to implement without operator supervision and, generally, without an independent information on the oil spill presence that could drive the choice of the best threshold. A different methodological approach (RAT, Robust AVHRR Techniques) proposed by Tramutoli (1998) and already successfully applied to several natural and environmental emergencies related to volcanic eruptions, forest fires and seismic activity. In this paper its extension to near real-time detection and monitoring of oil spills by means of NOAA-AVHRR (Advanced Very High Resolution Radiometer) records will be described. Briefly, RAT approach is an automatic change-detection scheme that considers a satellite image as a space-time process, described at each place (x,y) and time t, by the value of

  12. Geophysical Techniques for Monitoring CO2 Movement During Sequestration

    SciTech Connect

    Erika Gasperikova; G. Michael Hoversten

    2005-11-15

    The relative merits of the seismic, gravity, and electromagnetic (EM) geophysical techniques are examined as monitoring tools for geologic sequestration of carbon dioxide (CO{sub 2}). This work does not represent an exhaustive study, but rather demonstrates the capabilities of a number of geophysical techniques for two synthetic modeling scenarios. The first scenario represents combined CO{sub 2} enhanced oil recovery (EOR) and sequestration in a producing oil field, the Schrader Bluff field on the north slope of Alaska, USA. EOR/sequestration projects in general and Schrader Bluff in particular represent relatively thin injection intervals with multiple fluid components (oil, hydrocarbon gas, brine, and CO{sub 2}). This model represents the most difficult end member of a complex spectrum of possible sequestration scenarios. The time-lapse performance of seismic, gravity, and EM techniques are considered for the Schrader Bluff model. The second scenario is a gas field that in general resembles conditions of Rio Vista reservoir in the Sacramento Basin of California. Surface gravity, and seismic measurements are considered for this model.

  13. Development of sensing techniques for weaponry health monitoring

    NASA Astrophysics Data System (ADS)

    Edwards, Eugene; Ruffin, Paul B.; Walker, Ebonee A.; Brantley, Christina L.

    2013-04-01

    Due to the costliness of destructive evaluation methods for assessing the aging and shelf-life of missile and rocket components, the identification of nondestructive evaluation methods has become increasingly important to the Army. Verifying that there is a sufficient concentration of stabilizer is a dependable indicator that the missile's double-based solid propellant is viable. The research outlined in this paper summarizes the Army Aviation and Missile Research, Development, and Engineering Center's (AMRDEC's) comparative use of nanoporous membranes, carbon nanotubes, and optical spectroscopic configured sensing techniques for detecting degradation in rocket motor propellant. The first sensing technique utilizes a gas collecting chamber consisting of nanoporous structures that trap the smaller solid propellant particles for measurement by a gas analysis device. In collaboration with NASA-Ames, sensing methods are developed that utilize functionalized single-walled carbon nanotubes as the key sensing element. The optical spectroscopic sensing method is based on a unique light collecting optical fiber system designed to detect the concentration of the propellant stabilizer. Experimental setups, laboratory results, and overall effectiveness of each technique are presented in this paper. Expectations are for the three sensing mechanisms to provide nondestructive evaluation methods that will offer cost-savings and improved weaponry health monitoring.

  14. Noble Gas Measurement and Analysis Technique for Monitoring Reprocessing Facilities

    SciTech Connect

    Charlton, William S

    1999-09-01

    An environmental monitoring technique using analysis of stable noble gas isotopic ratios on-stack at a reprocessing facility was developed. This technique integrates existing technologies to strengthen safeguards at reprocessing facilities. The isotopic ratios are measured using a mass spectrometry system and are compared to a database of calculated isotopic ratios using a Bayesian data analysis method to determine specific fuel parameters (e.g., burnup, fuel type, fuel age, etc.). These inferred parameters can be used by investigators to verify operator declarations. A user-friendly software application (named NOVA) was developed for the application of this technique. NOVA included a Visual Basic user interface coupling a Bayesian data analysis procedure to a reactor physics database (calculated using the Monteburns 3.01 code system). The integrated system (mass spectrometry, reactor modeling, and data analysis) was validated using on-stack measurements during the reprocessing of target fuel from a U.S. production reactor and gas samples from the processing of EBR-II fast breeder reactor driver fuel. These measurements led to an inferred burnup that matched the declared burnup with sufficient accuracy and consistency for most safeguards applications. The NOVA code was also tested using numerous light water reactor measurements from the literature. NOVA was capable of accurately determining spent fuel type, burnup, and fuel age for these experimental results. Work should continue to demonstrate the robustness of this system for production, power, and research reactor fuels.

  15. Using multi-frequency acoustic attenuation to monitor grain size and concentration of suspended sediment in rivers.

    PubMed

    Moore, S A; Le Coz, J; Hurther, D; Paquier, A

    2013-04-01

    Multi-frequency acoustic backscatter profiles recorded with side-looking acoustic Doppler current profilers are used to monitor the concentration and size of sedimentary particles suspended in fluvial environments. Data at 300, 600, and 1200 kHz are presented from the Isère River in France where the dominant particles in suspension are silt and clay sizes. The contribution of suspended sediment to the through-water attenuation was determined for three high concentration (> 100 mg/L) events and compared to theoretical values for spherical particles having size distributions that were measured by laser diffraction in water samples. Agreement was good for the 300 kHz data, but it worsened with increasing frequency. A method for the determination of grain size using multi-frequency attenuation data is presented considering models for spherical and oblate spheroidal particles. When the resulting size estimates are used to convert sediment attenuation to concentration, the spheroidal model provides the best agreement with optical estimates of concentration, but the aspect ratio and grain size that provide the best fit differ between events. The acoustic estimates of size were one-third the values from laser grain sizing. This agreement is encouraging considering optical and acoustical instruments measure different parameters. PMID:23556566

  16. Surface acoustic wave technique for the characterization of porous properties of microporous silicate thin films

    NASA Astrophysics Data System (ADS)

    Hietala, Susan Leslie

    1997-12-01

    Features of gas adsorption onto sol-gel derived microporous silicate thin films, for characterization of porous properties, are detailed using a surface acoustic wave (SAW) technique. Mass uptake and film effective modulus changes calculated from the SAW data are investigated in detail. The effects of stress and surface tension on the SAW sensor are calculated and found to be negligible in these experiments. Transient behavior recorded during nitrogen adsorption at 77 K is discussed in the context of mass uptake and effective modulus contributions. The time constant associated with the effective modulus calculation is consistent with that of diffusivity of nitrogen into a 5A zeolite. Further calculations indicate that the transient behavior is not due to thermal effects. A unique dual sensor SAW experiment to decouple the mass and effective modulus contributions to the frequency response was performed in conjunction with a Silicon beam-bending experiment. The beam-bending experiment results in a calculation of stress induced during adsorption of methanol on a microporous silicate thin film. The decoupled mass and effective modulus calculated from the SAW data have similar shaped isotherms, and are quite different from that of the stress developed in the Silicon beam. The total effective modulus change calculated from the SAW data is consistent with that calculated using Gassmann's equation. The SAW system developed for this work included unique electronics and customized hardware which is suitable for work under vacuum and at temperatures from 77K to 473K. This unique setup is suitable for running thin film samples on a Micromeritics ASAP 2000 Gas Adsorption unit in automatic mode. This setup is also general enough to be compatible with a custom gas adsorption unit and the beam bending apparatus, both using standard vacuum assemblies.

  17. Acoustic Emission Monitoring of the Syracuse Athena Temple: Scale Invariance in the Timing of Ruptures

    SciTech Connect

    Niccolini, G.; Carpinteri, A.; Lacidogna, G.; Manuello, A.

    2011-03-11

    We perform a comparative statistical analysis between the acoustic-emission time series from the ancient Greek Athena temple in Syracuse and the sequence of nearby earthquakes. We find an apparent association between acoustic-emission bursts and the earthquake occurrence. The waiting-time distributions for acoustic-emission and earthquake time series are described by a unique scaling law indicating self-similarity over a wide range of magnitude scales. This evidence suggests a correlation between the aging process of the temple and the local seismic activity.

  18. Monitoring Anthropogenic Ocean Sound from Shipping Using an Acoustic Sensor Network and a Compressive Sensing Approach †

    PubMed Central

    Harris, Peter; Philip, Rachel; Robinson, Stephen; Wang, Lian

    2016-01-01

    Monitoring ocean acoustic noise has been the subject of considerable recent study, motivated by the desire to assess the impact of anthropogenic noise on marine life. A combination of measuring ocean sound using an acoustic sensor network and modelling sources of sound and sound propagation has been proposed as an approach to estimating the acoustic noise map within a region of interest. However, strategies for developing a monitoring network are not well established. In this paper, considerations for designing a network are investigated using a simulated scenario based on the measurement of sound from ships in a shipping lane. Using models for the sources of the sound and for sound propagation, a noise map is calculated and measurements of the noise map by a sensor network within the region of interest are simulated. A compressive sensing algorithm, which exploits the sparsity of the representation of the noise map in terms of the sources, is used to estimate the locations and levels of the sources and thence the entire noise map within the region of interest. It is shown that although the spatial resolution to which the sound sources can be identified is generally limited, estimates of aggregated measures of the noise map can be obtained that are more reliable compared with those provided by other approaches. PMID:27011187

  19. Acoustic Techniques for Measuring Surface Sealing and Crusting of Agricultural Soils

    NASA Astrophysics Data System (ADS)

    Hickey, C. J.; Leary, D.; Dicarlo, D. A.

    2004-12-01

    The microtopography of soils is an important surface characteristic that effects water ponding, infiltration, and consequently soil erosion. During a rainstorm event the surface microtopography and soil matrix evolve, thereby altering the erosion and runoff dynamics. The impact of raindrops cause the breakdown of soil aggregates into smaller particles, which can then be deposited into the smaller depressions. The redistribution of soil particles on the surface during rainfall produce a thin surface layer often referred to as surface sealing or crusting. For the purpose of this presentation, surface sealing will be used to describe a reduction in the ability of fluid to flow across the surface. Surface crusting will be associated with the formation of a thin layer of higher stiffness or larger mechanical strength. The sensitivity of acoustics to the effects of sealing and crusting was examined by measuring the acoustic-to seismic (A/S) transfer function and acoustic reflectivity on two different soils in a dry, wetted and rained-on state. The A/S transfer function measurement involves the use of a suspended loud speaker to impinge acoustic energy from the air onto the sample and a laser Doppler vibrometer (LDV) is used to measure the induced surface particle velocity. Therefore, the A/S transfer function is a measure of the seismic energy that has been transferred into the soil from the airborne wave. The acoustic surface reflectivity is a measurement of the amount of acoustic energy reflected from the surface and requires the use of a microphone suspended above the surface. Results suggests that the seismic energy transferred (A/S transfer function) is sensitive to crust formation but is not as sensitive to sealing. The amount of reflected acoustic energy appears to be more sensitive to sealing than crusting.

  20. Comparison of acoustic and conventional flow measurement techniques at the Raccoon Mountain Pumped-Storage Plant: Final report

    SciTech Connect

    March, P.A.; Missimer, J.R.; Voss, A.; Pearson, H.S.

    1987-08-01

    The Electric Power Research Institute (EPRI) initiated a research project to evaluate the technical and economic feasibility of using the acoustic method of flow measurement in hydroelectric power plant efficiency tests. As a portion of this program, the Tennessee Valley Authority's (TVA) Raccoon Mountain Pumped-Storage Plant was chosen as one of the sites to be tested. The primary objective of the TVA test was to compare the measurements of the Ocean Research Engineering (ORE), acoustic flowmeter installed on Unit 1 to the Volumetric and Winter-Kennedy Techniques for flow measurement. The Winter-Kennedy Technique is the standard flow measurement technique used in the plant. The Volumetric Technique consisted of accurate measurement of the upper reservoir volume over specified time increments. For calibration, the upper reservoir was initially drained and as it was being filled, aerial photographs were taken to obtain contour lines which were correlated with simultaneous stage measurements. The photographs were used to compute the differential volume of the reservoir associated with a change in stage. Six performance tests were conducted on Unit 1. During the tests no other units were operated. Five tests were conducted in the generating mode and one test was conducted in the pumping mode. The uncertainty in the measurements using the Volumetric Technique is of the order of 0.5 percent for changes of stage elevation in excess of two feet. The flowrate measured by the ORE acoustic flowmeter was consistently of the order of 1.5 percent lower than the flowrate determined from the Volumetric Technique in both the generating and pumping modes. 3 refs., 32 figs., 14 tabs.

  1. Speed of sound and acoustic attenuation of compounds affected during optoacoustic monitoring of thermal therapies measured in the temperature range from 5°C to 60°C

    NASA Astrophysics Data System (ADS)

    Oruganti, Tanmayi; Petrova, Elena; Oraevsky, Alexander A.; Ermilov, Sergey A.

    2015-03-01

    Optoacoustic (photoacoustic) imaging is being adopted for monitoring tissue temperature during hypothermic and hyperthermic cancer treatments. The technique's accuracy benefits from the knowledge of speed of sound (SoS) and acoustic coefficient of attenuation (AcA) as they change with temperature in biological tissues, blood, and acoustic lens of an ultrasound probe. In these studies we measured SoS and AcA of different ex vivo tissues and blood components (plasma and erythrocyte concentrates) in the temperature range from 5°C to 60°C. We used the technique based on measurements of time-delay and spectral amplitude of pressure pulses generated by wideband planar acoustic waves propagating through the interrogated medium. Water was used as a reference medium with known acoustic properties. In order to validate our experimental technique, we measured the temperature dependence of SoS and AcA for aqueous NaCl solution of known concentration and obtained the results in agreement with published data. Similar to NaCl solution and pure water, SoS in blood and plasma was monotonously increasing with temperature. However, SoS of erythrocyte concentrates displayed abnormalities at temperatures above 45°C, suggesting potential effects from hemoglobin denaturation and/or hemolysis of erythrocytes. On the contrary to aqueous solutions, the SoS in polyvinyl-chloride (plastisol) - a material frequently used for mimicking optical and acoustic properties of tissues - decreased with temperature. We also measured SoS and AcA in silicon material of an acoustic lens and did not observe temperature-related changes of SoS.

  2. Monitoring Microbe-Induced Sulfide Precipitation Under Dynamic Flow Conditions Using Multiple Geophysical Techniques

    NASA Astrophysics Data System (ADS)

    Williams, K. H.; Hubbard, S.; Ntarlagiannis, D.; Banfield, J.

    2004-05-01

    A laboratory study was undertaken to investigate the feasibility of using minimally invasive geophysical techniques to monitor microbe-induced sulfide precipitation in saturated sand-packed columns under dynamic flow conditions. Specifically, the effect of zinc and iron sulfide precipitation on geophysical signatures was evaluated during stimulated sulfate-reduction by Desulfovibrio vulgaris. Four inoculated columns and one non-inoculated control were operated under a continuous upward flow velocity of 50cm/day with the following measurements made: multi-port fluid sampling, cross-column acoustic wave propagation, induced polarization, time domain reflectometry and saturated hydraulic conductivity. Over a period of seven weeks, the onset and progression of sulfate reduction within the columns was confirmed through decreasing substrate and aqueous metals concentrations, increased biomass, and visible regions of sulfide accumulation. Decreases in initial lactate and sulfate concentrations (2.8mM and 4.0mM, respectively) followed predicted stoichiometric relationships and soluble Zn(II) and Fe(II) concentrations (0.31mM and 0.36mM, respectively) were reduced to levels below detection through sequestration as insoluble sulfide phases. The areas where sulfide precipitation and accumulation occurred resulted in significant changes in two of the three geophysical measurements. High frequency (400-600kHz) acoustic wave amplitudes were reduced by nearly an order of magnitude over the course of the experiment with no significant accompanying change in wave velocity. Neither the wave amplitudes nor the velocities changed significantly in the downgradient portions of the column where microbial activity and sulfide precipitation were depressed due to depleted substrate and metals concentrations. The frequency content of the transmitted waves remained unchanged throughout the course of the experiment. Over the frequency range of the induced polarization measurements (0.1-1000Hz

  3. Use of the acoustic impulse-response technique for the nondestructive assessment of Manchego cheese texture.

    PubMed

    Benedito, J; Conde, T; Clemente, G; Mulet, A

    2006-12-01

    Manchego cheese pieces were hit with an impact probe and the acoustic response was recorded, analyzed, and used to assess the textural characteristics of the cheese pieces. The textural parameters measured by traditional instrumental methods increased during ripening, although the pattern of the increase was different for different batches. For the 2 acoustic impact probes used in this study, a change in the frequency spectrum took place as cheese matured, increasing higher frequencies and the energy content. Multiple linear regression (MLR) and partial least square regression (PLSR), considering the acoustical variables extracted from the spectrum, allowed for a good estimation of cheese texture. The textural characteristics of the cheese surface and in particular the maximum force in compression experiments (R(2) > 0.937 for MLR and R(2) > 0.852 for PLSR) were accurately predicted by the acoustic method; however, the texture of the central layers of the cheese are poorly assessed (R(2) < 0.720). The results obtained show the feasibility of using acoustic systems to assess Manchego cheese texture, aiding its classification. PMID:17106079

  4. Remote sensing techniques for soil moisture and agricultural drought monitoring

    NASA Astrophysics Data System (ADS)

    Wang, Lingli

    Drought is the most complex and least understood of all natural hazards, affecting more people than any other hazard. Soil moisture is a primary indicator for agricultural drought. This dissertation is aimed at evaluating and investigating soil moisture and drought monitoring using remote sensing techniques. Recent technological advances in remote sensing have shown that soil moisture can be measured by a variety of remote sensing techniques, each with its own strengths and weaknesses. This research is designed to combine the strengths of optical/infrared as well as microwave remote sensing approaches for soil moisture estimation. A soil moisture estimation algorithm at moderate resolution was developed based on the well known 'Universal Triangle' relation by using MODIS land parameters as well as ground measured soil moisture. Though lower in spatial resolution, AMSR-E microwave measurements provides daily global soil moisture of the top soil layer, which are typically less affected by clouds, making them complementary to MODIS measurements over regions of clouds. Considering that the 'Universal Triangle' approach for soil moisture estimation is based on empirical relations which lack solid physical basis, a new physics based drought index, the Normalized Multi-band Drought Index (NMDI) was proposed for monitoring soil and vegetation moisture from space by using one near-infrared (NIR) and two shortwave infrared (SWIR) channels. Typical soil reflectance spectra and satellite acquired canopy reflectances are used to validate the usefulness of NMDI. Its ability for active fire detection has also been investigated using forest fires burning in southern Georgia, USA and southern Greece in 2007. Combining information from multiple NIR and SWIR channels makes NMDI a most promising indicator for drought monitoring and active fire detecting. Given the current technology, satellite remote sensing can only provide soil moisture measurements for the top soil profile, and

  5. In situ sensor techniques in modern bioprocess monitoring.

    PubMed

    Beutel, Sascha; Henkel, Steffen

    2011-09-01

    New reactor concepts as multi-parallel screening systems or disposable bioreactor systems for decentralized and reproducible production increase the need for new and easy applicable sensor technologies to access data for process control. These sophisticated reactor systems require sensors to work with the lowest sampling volumes or, even better, to measure directly in situ, but in situ sensors are directly incorporated into a reactor or fermenter within the sterility barrier and have therefore to stand the sterilization procedures. Consequently, these in situ sensor technologies should enable the measurement of multi-analytes simultaneously online and in real-time at a low price for the robust sensing element. Current research therefore focuses on the implementation of noninvasive spectroscopic and optical technologies, and tries to employ them through fiber optics attached to disposable sensing connectors. Spectroscopic methods reach from ultraviolet to infrared and further comprising fluorescence and Raman spectroscopy. Also, optic techniques like microscopy are adapted for the direct use in bioreactor systems (Ulber et al. in Anal Bioanal Chem 376:342-348, 2003) as well as various electrochemical methods (Joo and Brown in Chem Rev 108:638-651, 2008). This review shows the variety of modern in situ sensing principles in bioprocess monitoring with emphasis on spectroscopic and optical techniques and the progress in the adaption to latest reactor concepts. PMID:21785932

  6. Acoustic emission signal processing technique to characterize reactor in-pile phenomena

    SciTech Connect

    Agarwal, Vivek; Tawfik, Magdy S.; Smith, James A.

    2015-03-31

    Existing and developing advanced sensor technologies and instrumentation will allow non-intrusive in-pile measurement of temperature, extension, and fission gases when coupled with advanced signal processing algorithms. The transmitted measured sensor signals from inside to the outside of containment structure are corrupted by noise and are attenuated, thereby reducing the signal strength and the signal-to-noise ratio. Identification and extraction of actual signal (representative of an in-pile phenomenon) is a challenging and complicated process. In the paper, empirical mode decomposition technique is utilized to reconstruct actual sensor signal by partially combining intrinsic mode functions. Reconstructed signal will correspond to phenomena and/or failure modes occurring inside the reactor. In addition, it allows accurate non-intrusive monitoring and trending of in-pile phenomena.

  7. Acoustic Emission Signal Processing Technique to Characterize Reactor In-Pile Phenomena

    SciTech Connect

    Vivek Agarwal; Magdy Samy Tawfik; James A Smith

    2014-07-01

    Existing and developing advanced sensor technologies and instrumentation will allow non-intrusive in-pile measurement of temperature, extension, and fission gases when coupled with advanced signal processing algorithms. The transmitted measured sensor signals from inside to the outside of containment structure are corrupted by noise and are attenuated, thereby reducing the signal strength and signal-to-noise ratio. Identification and extraction of actual signal (representative of an in-pile phenomenon) is a challenging and complicated process. In this paper, empirical mode decomposition technique is proposed to reconstruct actual sensor signal by partially combining intrinsic mode functions. Reconstructed signal corresponds to phenomena and/or failure modes occurring inside the reactor. In addition, it allows accurate non-intrusive monitoring and trending of in-pile phenomena.

  8. Acoustic emission non-destructive testing of structures using source location techniques.

    SciTech Connect

    Beattie, Alan G.

    2013-09-01

    The technology of acoustic emission (AE) testing has been advanced and used at Sandia for the past 40 years. AE has been used on structures including pressure vessels, fire bottles, wind turbines, gas wells, nuclear weapons, and solar collectors. This monograph begins with background topics in acoustics and instrumentation and then focuses on current acoustic emission technology. It covers the overall design and system setups for a test, with a wind turbine blade as the object. Test analysis is discussed with an emphasis on source location. Three test examples are presented, two on experimental wind turbine blades and one on aircraft fire extinguisher bottles. Finally, the code for a FORTRAN source location program is given as an example of a working analysis program. Throughout the document, the stress is on actual testing of real structures, not on laboratory experiments.

  9. Health Monitoring of Composite Material Structures Using a Vibrometry Technique

    NASA Technical Reports Server (NTRS)

    Schulz, Mark J.

    1998-01-01

    Non-destructive evaluation (NDE) methods for quantifying and locating damage are essential for inspecting structures to ensure safety and reliability. Transmittance function monitoring is a potentially new NDE technique being tested as a tool to detect, quantify, and locate damage on flexible structures. The technique has a large spatial range that is practical for detecting damage on large composite material structures such as a reusable launch vehicle. The Transmittance Function (TF) theory is based on structural dynamics principles that define how vibration at one point in a structure is related to a force at another point. This relationship is called the Frequency Response Function (FRF). A Transmittance Function (TF) is derived as the ratio of FRFs, and can detect damage because the FRFs change due to damage. If one excitation is used for the testing, the force does not need to be measured to compute the TF. In the damage detection procedure, the structure is subjected to wide-band vibration and TFs are computed between different accelerometers to detect changes in the structure, presumably due to damage. In the first year of the project the TF method was tested on a bolted panel, a curved panel, and beams, all made of fiberglass. It was shown that damage could be detected using low frequency vibration, 250 to 1,250 Hz. The technique is sensitive to damage, but it requires storage of historical or pre-damage TFs for the healthy structure. This would become a large data storage requirement for large structures. Thus one objective for the second year of the project was to eliminate the need to store historical data. The second year report gives details of how storage of historical data was eliminated. Further results of testing panel structures are also given.

  10. A synchronized particle image velocimetry and infrared thermography technique applied to an acoustic streaming flow

    PubMed Central

    Sou, In Mei; Layman, Christopher N.; Ray, Chittaranjan

    2013-01-01

    Subsurface coherent structures and surface temperatures are investigated using simultaneous measurements of particle image velocimetry (PIV) and infrared (IR) thermography. Results for coherent structures from acoustic streaming and associated heating transfer in a rectangular tank with an acoustic horn mounted horizontally at the sidewall are presented. An observed vortex pair develops and propagates in the direction along the centerline of the horn. From the PIV velocity field data, distinct kinematic regions are found with the Lagrangian coherent structure (LCS) method. The implications of this analysis with respect to heat transfer and related sonochemical applications are discussed. PMID:24347810

  11. A synchronized particle image velocimetry and infrared thermography technique applied to an acoustic streaming flow.

    PubMed

    Sou, In Mei; Allen, John S; Layman, Christopher N; Ray, Chittaranjan

    2011-11-01

    Subsurface coherent structures and surface temperatures are investigated using simultaneous measurements of particle image velocimetry (PIV) and infrared (IR) thermography. Results for coherent structures from acoustic streaming and associated heating transfer in a rectangular tank with an acoustic horn mounted horizontally at the sidewall are presented. An observed vortex pair develops and propagates in the direction along the centerline of the horn. From the PIV velocity field data, distinct kinematic regions are found with the Lagrangian coherent structure (LCS) method. The implications of this analysis with respect to heat transfer and related sonochemical applications are discussed. PMID:24347810

  12. Method and apparatus for acoustically monitoring the flow of suspended solid particulate matter. [Patent application; monitoring char flow in coal gasifier

    DOEpatents

    Roach, P.D.; Raptis, A.C.

    1980-11-24

    A method and apparatus for monitoring char flow in a coal gasifier system includes flow monitor circuits which measure acoustic attenuation caused by the presence of char in a char line and provides a char flow/no flow indication and an indication of relative char density. The flow monitor circuits compute the ratio of signals in two frequency bands, a first frequency band representative of background noise, and a second higher frequency band in which background noise is attenuated by the presence of char. Since the second frequency band contains higher frequencies, the ratio can be used to provide a flow/no flow indication. The second band can also be selected so that attenuation is monotonically related to particle concentration, providing a quantitative measure of char concentration.

  13. Benthic habitat mapping: A review of progress towards improved understanding of the spatial ecology of the seafloor using acoustic techniques

    NASA Astrophysics Data System (ADS)

    Brown, Craig J.; Smith, Stephen J.; Lawton, Peter; Anderson, John T.

    2011-05-01

    This review examines the various strategies and methods used to produce benthic habitat maps using acoustic remote sensing techniques, coupled with in situ sampling. The applications of three acoustic survey techniques are examined in detail: single-beam acoustic ground discrimination systems, sidescan sonar systems, and multi-beam echo sounders. Over the past decade we have witnessed the nascence of the field of benthic habitat mapping and, on the evidence of the literature reviewed in this paper, have seen a rapid evolution in the level of sophistication in our ability to image and thus map seafloor habitats. As acoustic survey tools have become ever more complex, new methods have been tested to segment, classify and combine these data with biological ground truth sample data. Although the specific methods used to derive habitat maps vary considerably, the review indicates that studies can generally be categorized into one of three over-arching strategies; 1) Abiotic surrogate mapping; 2) Assemble first, predict later (unsupervised classification); 3) Predict first, assemble later (supervised classification). Whilst there is still no widely accepted agreement on the best way to produce benthic habitat maps, all three strategies provide valuable map resources to support management objectives. Whilst there is still considerable work to be done before we can answer many of the outstanding technological, methodological, ecological and theoretical questions that have been raised here, the review concludes that the advent of spatial ecological studies founded on high-resolution environmental data sets will undoubtedly help us to examine patterns in community and species distributions. This is a vital first step in unraveling ecological complexities and thus providing improved spatial information for management of marine systems.

  14. Development of acoustic model-based iterative reconstruction technique for thick-concrete imaging

    NASA Astrophysics Data System (ADS)

    Almansouri, Hani; Clayton, Dwight; Kisner, Roger; Polsky, Yarom; Bouman, Charles; Santos-Villalobos, Hector

    2016-02-01

    Ultrasound signals have been used extensively for non-destructive evaluation (NDE). However, typical reconstruction techniques, such as the synthetic aperture focusing technique (SAFT), are limited to quasi-homogenous thin media. New ultrasonic systems and reconstruction algorithms are in need for one-sided NDE of non-homogenous thick objects. An application example space is imaging of reinforced concrete structures for commercial nuclear power plants (NPPs). These structures provide important foundation, support, shielding, and containment functions. Identification and management of aging and degradation of concrete structures is fundamental to the proposed long-term operation of NPPs. Another example is geothermal and oil/gas production wells. These multi-layered structures are composed of steel, cement, and several types of soil and rocks. Ultrasound systems with greater penetration range and image quality will allow for better monitoring of the well's health and prediction of high-pressure hydraulic fracturing of the rock. These application challenges need to be addressed with an integrated imaging approach, where the application, hardware, and reconstruction software are highly integrated and optimized. Therefore, we are developing an ultrasonic system with Model-Based Iterative Reconstruction (MBIR) as the image reconstruction backbone. As the first implementation of MBIR for ultrasonic signals, this paper document the first implementation of the algorithm and show reconstruction results for synthetically generated data.1

  15. Development of Acoustic Model-Based Iterative Reconstruction Technique for Thick-Concrete Imaging

    SciTech Connect

    Almansouri, Hani; Clayton, Dwight A; Kisner, Roger A; Polsky, Yarom; Bouman, Charlie; Santos-Villalobos, Hector J

    2016-01-01

    Ultrasound signals have been used extensively for non-destructive evaluation (NDE). However, typical reconstruction techniques, such as the synthetic aperture focusing technique (SAFT), are limited to quasi-homogenous thin media. New ultrasonic systems and reconstruction algorithms are in need for one-sided NDE of non-homogenous thick objects. An application example space is imaging of reinforced concrete structures for commercial nuclear power plants (NPPs). These structures provide important foundation, support, shielding, and containment functions. Identification and management of aging and degradation of concrete structures is fundamental to the proposed long-term operation of NPPs. Another example is geothermal and oil/gas production wells. These multi-layered structures are composed of steel, cement, and several types of soil and rocks. Ultrasound systems with greater penetration range and image quality will allow for better monitoring of the well's health and prediction of high-pressure hydraulic fracturing of the rock. These application challenges need to be addressed with an integrated imaging approach, where the application, hardware, and reconstruction software are highly integrated and optimized. Therefore, we are developing an ultrasonic system with Model-Based Iterative Reconstruction (MBIR) as the image reconstruction backbone. As the first implementation of MBIR for ultrasonic signals, this paper document the first implementation of the algorithm and show reconstruction results for synthetically generated data.

  16. Development of Acoustic Model-Based Iterative Reconstruction Technique for Thick-Concrete Imaging

    SciTech Connect

    Almansouri, Hani; Clayton, Dwight A; Kisner, Roger A; Polsky, Yarom; Bouman, Charlie; Santos-Villalobos, Hector J

    2015-01-01

    Ultrasound signals have been used extensively for non-destructive evaluation (NDE). However, typical reconstruction techniques, such as the synthetic aperture focusing technique (SAFT), are limited to quasi-homogenous thin media. New ultrasonic systems and reconstruction algorithms are in need for one-sided NDE of non-homogenous thick objects. An application example space is imaging of reinforced concrete structures for commercial nuclear power plants (NPPs). These structures provide important foundation, support, shielding, and containment functions. Identification and management of aging and degradation of concrete structures is fundamental to the proposed long-term operation of NPPs. Another example is geothermal and oil/gas production wells. These multi-layered structures are composed of steel, cement, and several types of soil and rocks. Ultrasound systems with greater penetration range and image quality will allow for better monitoring of the well s health and prediction of high-pressure hydraulic fracturing of the rock. These application challenges need to be addressed with an integrated imaging approach, where the application, hardware, and reconstruction software are highly integrated and optimized. Therefore, we are developing an ultrasonic system with Model-Based Iterative Reconstruction (MBIR) as the image reconstruction backbone. As the first implementation of MBIR for ultrasonic signals, this paper document the first implementation of the algorithm and show reconstruction results for synthetically generated data.

  17. Investigation of hydrogen embrittlement in 4130 steel using acoustic emission techniques

    SciTech Connect

    Susetka, S.L.

    1986-01-01

    Hydrogen embrittlement has long been a problem in certain quenched and tempered steel weldments since it reduces fracture strength and ductility. Although the phenomenon has been studied extensively, controversy still exists over the interaction between hydrogen and the lattice. For this investigation the acoustic emission response from fracture roughness tests on a variety of microstructures of AISI 4130 steel was used to gain insight into the micromechanism of the fracture process. The data indicate the acoustic emission represents the onset of brittle crack extension and, further, that the summation of the square of the acoustic emission amplitude, ..sigma..g/sup 2/, represents the elastic energy released during the fracture process. A comparison of the acoustic emission response from hydrogen charged and uncharged samples reveals that hydrogen increases the elastic energy released for the same crack extension. The 20% increase in the brittle fracture are in hydrogen charged samples is insufficient to explain the two fold increase in ..sigma..g/sup 2/. The data also support the view that hydrogen can act to alter the relationship between the surface energy, ..gamma../sub s/, and the plastic work term, ..gamma../sub p/, as Thomson, McMahon, and Gilman have proposed.

  18. ACOUSTIC TECHNIQUES FOR THE MAPPING OF THE DISTRIBUTION OF CONTAMINATED SEDIMENTS

    EPA Science Inventory

    An overview of the last 30 years of analytical research into the acoustic properties of harbor marine sediments has allowed the extension of the original work of Hamilton (1970) into a production system for classifying the density and bulk physical properties of standard marine s...

  19. A new setup for studying thermal microcracking through acoustic emission monitoring

    NASA Astrophysics Data System (ADS)

    Griffiths, Luke; Heap, Michael; Baud, Patrick; Schmittbuhl, Jean

    2016-04-01

    Thermal stressing is common in geothermal environments and has been shown in the laboratory to induce changes in the physical and mechanical properties of rocks. These changes are generally considered to be a consequence of the generation of thermal microcracks and debilitating chemical reactions. Thermal microcracks form as a result of the build-up of internal stresses due to: (1) the thermal expansion mismatch between the different phases present in the material, (2) thermal expansion anisotropy within individual minerals, and (3) thermal gradients. The generation of cracks during thermal stressing has been monitored in previous studies using the output of acoustic emissions (AE), a common proxy for microcrack damage, and through microstructural observations. Here we present a new experimental setup which is optimised to record AE from a rock sample at high temperatures and under a servo-controlled uniaxial stress. The design is such that the AE transducer is embedded in the top of the piston, which acts as a continuous wave guide to the sample. In this way, we simplify the ray path geometry whilst minimising the number of interfaces between the microcrack and the transducer, maximising the quality of the signal. This allows for an in-depth study of waveform attributes such as energy, amplitude, counts and duration. Furthermore, the capability of this device to apply a servo-controlled load on the sample, whilst measuring strain in real time, leads to a spectrum of possible tests combining mechanical and thermal stress. It is also an essential feature to eliminate the build-up of stresses through thermal expansion of the pistons and the sample. We plan a systematic experimental study of the AE of thermally stressed rock during heating and cooling cycles. We present results from pilot tests performed on Darley Dale sandstone and Westerly granite. Understanding the effects of thermal stressing in rock is of particular interest at a geothermal site, where

  20. A passive acoustic monitoring method applied to observation and group size estimation of finless porpoises.

    PubMed

    Wang, Kexiong; Wang, Ding; Akamatsu, Tomonari; Li, Songhai; Xiao, Jianqiang

    2005-08-01

    The present study aimed at determining the detection capabilities of an acoustic observation system to recognize porpoises under local riverine conditions and compare the results with sighting observations. Arrays of three to five acoustic data loggers were stationed across the main channel of the Tian-e-zhou Oxbow of China's Yangtze River at intervals of 100-150 m to record sonar signals of free-ranging finless porpoises (Neophocaena phocaenoides). Acoustic observations, concurrent with visual observations, were conducted at two occasions on 20-22 October 2003 and 17-19 October 2004. During a total of 42 h of observation, 316 finless porpoises were sighted and 7041 sonar signals were recorded by loggers. The acoustic data loggers recorded ultrasonic signals of porpoises clearly, and detected the presence of porpoises with a correct detection level of 77.6% and a false alarm level of 5.8% within an effective distance of 150 m. Results indicated that the stationed passive acoustic observation method was effective in detecting the presence of porpoises and showed potential in estimating the group size. A positive linear correlation between the number of recorded signals and the group size of sighted porpoises was indicated, although it is faced with some uncertainty and requires further investigation. PMID:16158672

  1. An acoustic travel time method for continuous velocity monitoring in shallow tidal streams

    NASA Astrophysics Data System (ADS)

    Razaz, Mahdi; Kawanisi, Kiyosi; Nistor, Ioan; Sharifi, Soroosh

    2013-08-01

    Long-term variations of streamflow in a tidal channel were measured using a Fluvial Acoustic Tomography (FAT) system through one transmission path. FAT is an innovative acoustic technology that utilizes the time-of-travel method to determine velocity between two points from multiple ray paths that traverse the entire cross-section of stream. Due to high spatial variability of flow distribution stationary ADCP measurements were not likely to yield true section-averaged flow velocity and moving-boat ADCP method was therefore used to provide reference data. As such, two short-term moving boat ADCP campaigns were carried out by the authors. In the first campaign, a couple of acoustic stations were added to the FAT system in order to resolve flow angularity in addition to the mean velocity. Comparing the FAT results with corresponding ADCP section-averaged flow direction and velocity indicated remarkable consistency. Second campaign was designed to capture the influence of salt wedge intrusion on the sound propagation pattern. It was found that FAT velocity measurements bias high if acoustic stations lay inside the cooler freshwater layer. Ray-tracing hindcasts suggest that installing acoustic stations inside the salt wedge may significantly improve function of output of the system. Comparing salinities evaluated from long-term FAT travel time records with nodal salinity measurements provided by conductivity-temperature sensors reveals the potential ability of FAT in measuring salt flux.

  2. A passive acoustic monitoring method applied to observation and group size estimation of finless porpoises.

    PubMed

    Wang, Kexiong; Wang, Ding; Akamatsu, Tomonari; Li, Songhai; Xiao, Jianqiang

    2005-08-01

    The present study aimed at determining the detection capabilities of an acoustic observation system to recognize porpoises under local riverine conditions and compare the results with sighting observations. Arrays of three to five acoustic data loggers were stationed across the main channel of the Tian-e-zhou Oxbow of China's Yangtze River at intervals of 100-150 m to record sonar signals of free-ranging finless porpoises (Neophocaena phocaenoides). Acoustic observations, concurrent with visual observations, were conducted at two occasions on 20-22 October 2003 and 17-19 October 2004. During a total of 42 h of observation, 316 finless porpoises were sighted and 7041 sonar signals were recorded by loggers. The acoustic data loggers recorded ultrasonic signals of porpoises clearly, and detected the presence of porpoises with a correct detection level of 77.6% and a false alarm level of 5.8% within an effective distance of 150 m. Results indicated that the stationed passive acoustic observation method was effective in detecting the presence of porpoises and showed potential in estimating the group size. A positive linear correlation between the number of recorded signals and the group size of sighted porpoises was indicated, although it is faced with some uncertainty and requires further investigation.

  3. Underwater Acoustics.

    ERIC Educational Resources Information Center

    Creasey, D. J.

    1981-01-01

    Summarizes the history of underwater acoustics and describes related research studies and teaching activities at the University of Birmingham (England). Also includes research studies on transducer design and mathematical techniques. (SK)

  4. Investigation of Various Condition Monitoring Techniques Based on a Damaged Wind Turbine Gearbox

    SciTech Connect

    Sheng, S.

    2011-10-01

    This paper is a continuation of a 2009 paper presented at the 7th International Workshop on Structural Health Monitoring that described various wind turbine condition-monitoring techniques. This paper presents the results obtained by various condition- monitoring techniques from a damaged Gearbox Reliability Collaborative test gearbox.

  5. Passive Acoustic Monitoring of the Environmental Impact of Oil Exploration on Marine Mammals in the Gulf of Mexico.

    PubMed

    Sidorovskaia, Natalia A; Ackleh, Azmy S; Tiemann, Christopher O; Ma, Baoling; Ioup, Juliette W; Ioup, George E

    2016-01-01

    The Gulf of Mexico is a region densely populated by marine mammals that must adapt to living in a highly active industrial environment. This paper presents a new approach to quantifying the anthropogenic impact on the marine mammal population. The results for sperm and beaked whales of a case study of regional population dynamics trends after the Deepwater Horizon oil spill, derived from passive acoustic-monitoring data gathered before and after the spill in the vicinity of the accident, are presented. PMID:26611062

  6. Facial nerve dissection by use of acoustic (loudspeaker) facial EMG monitoring.

    PubMed

    Kinney, S E; Prass, R

    1986-11-01

    The development of the surgical microscope in 1953, and the subsequent development of microsurgical instrumentation, signaled the beginning of modern-day acoustic neuroma surgery. Preservation of facial nerve function and total tumor removal is the goal of all acoustic neuroma surgery. The refinement of the translabyrinthine removal of acoustic neuromas by Dr. William House significantly improved preservation of facial nerve function. This is made possible by the anatomic identification of the facial nerve at the lateral end of the internal auditory canal. When the surgery is accomplished from a suboccipital or retrosigmoid approach, the facial nerve may be identified at the brain stem or within the internal auditory canal. Identifying the facial nerve from the posterior approach is not as anatomically precise as from the lateral approach through the labyrinth. The use of a facial nerve stimulator can greatly facilitate identification of the facial nerve in these procedures.

  7. A Permanent Automated Real-Time Passive Acoustic Monitoring System for Bottlenose Dolphin Conservation in the Mediterranean Sea

    PubMed Central

    Brunoldi, Marco; Bozzini, Giorgio; Casale, Alessandra; Corvisiero, Pietro; Grosso, Daniele; Magnoli, Nicodemo; Alessi, Jessica; Bianchi, Carlo Nike; Mandich, Alberta; Morri, Carla; Povero, Paolo; Wurtz, Maurizio; Melchiorre, Christian; Viano, Gianni; Cappanera, Valentina; Fanciulli, Giorgio; Bei, Massimiliano; Stasi, Nicola; Taiuti, Mauro

    2016-01-01

    Within the framework of the EU Life+ project named LIFE09 NAT/IT/000190 ARION, a permanent automated real-time passive acoustic monitoring system for the improvement of the conservation status of the transient and resident population of bottlenose dolphin (Tursiops truncatus) has been implemented and installed in the Portofino Marine Protected Area (MPA), Ligurian Sea. The system is able to detect the simultaneous presence of dolphins and boats in the area and to give their position in real time. This information is used to prevent collisions by diffusing warning messages to all the categories involved (tourists, professional fishermen and so on). The system consists of two gps-synchronized acoustic units, based on a particular type of marine buoy (elastic beacon), deployed about 1 km off the Portofino headland. Each one is equipped with a four-hydrophone array and an onboard acquisition system which can record the typical social communication whistles emitted by the dolphins and the sound emitted by boat engines. Signals are pre-filtered, digitized and then broadcast to the ground station via wi-fi. The raw data are elaborated to get the direction of the acoustic target to each unit, and hence the position of dolphins and boats in real time by triangulation. PMID:26789265

  8. A high-speed high-sensitivity acoustic cell for in-line continuous monitoring of MOCVD precursor gases

    NASA Astrophysics Data System (ADS)

    Wajid, A.; Gogol, C.; Hurd, C.; Hetzel, M.; Spina, A.; Lum, R.; McDonald, M.; Capik, R. J.

    1997-01-01

    We describe a continuous wave resonant acoustic sensor that has been optimized as a very sensitive in-line monitor for measuring the composition of precursor gases used in MOCVD processes. The precursor/carrier gas mixtures flow through a compact stainless steel acoustic chamber that is isolated from the acoustic transducers by a set of metallic diaphragms. The sensor has been successfully operated at supply line pressures from atmosphere down to 50 Torr with gas flow rates of up to 1600 sccm. The accuracy of the speed of sound measurement for hydrogen gas is better than 0.005%, even in a high noise and low pressure environment. Hydrogen, as well as nitrogen or argon carrier gases, are accommodated within the instrument's 1-5 kHz working frequency range. The instrument's sensitivity and stability are demonstrated with the laboratory data. Measurements of the dynamic response characteristics of the metalorganic bubbler lines at low pressure are also be presented. Application of the cell is general, encompassing any of the metalorganic and hydride materials typically used in MOCVD processes.

  9. A Permanent Automated Real-Time Passive Acoustic Monitoring System for Bottlenose Dolphin Conservation in the Mediterranean Sea.

    PubMed

    Brunoldi, Marco; Bozzini, Giorgio; Casale, Alessandra; Corvisiero, Pietro; Grosso, Daniele; Magnoli, Nicodemo; Alessi, Jessica; Bianchi, Carlo Nike; Mandich, Alberta; Morri, Carla; Povero, Paolo; Wurtz, Maurizio; Melchiorre, Christian; Viano, Gianni; Cappanera, Valentina; Fanciulli, Giorgio; Bei, Massimiliano; Stasi, Nicola; Taiuti, Mauro

    2016-01-01

    Within the framework of the EU Life+ project named LIFE09 NAT/IT/000190 ARION, a permanent automated real-time passive acoustic monitoring system for the improvement of the conservation status of the transient and resident population of bottlenose dolphin (Tursiops truncatus) has been implemented and installed in the Portofino Marine Protected Area (MPA), Ligurian Sea. The system is able to detect the simultaneous presence of dolphins and boats in the area and to give their position in real time. This information is used to prevent collisions by diffusing warning messages to all the categories involved (tourists, professional fishermen and so on). The system consists of two gps-synchronized acoustic units, based on a particular type of marine buoy (elastic beacon), deployed about 1 km off the Portofino headland. Each one is equipped with a four-hydrophone array and an onboard acquisition system which can record the typical social communication whistles emitted by the dolphins and the sound emitted by boat engines. Signals are pre-filtered, digitized and then broadcast to the ground station via wi-fi. The raw data are elaborated to get the direction of the acoustic target to each unit, and hence the position of dolphins and boats in real time by triangulation.

  10. A Permanent Automated Real-Time Passive Acoustic Monitoring System for Bottlenose Dolphin Conservation in the Mediterranean Sea.

    PubMed

    Brunoldi, Marco; Bozzini, Giorgio; Casale, Alessandra; Corvisiero, Pietro; Grosso, Daniele; Magnoli, Nicodemo; Alessi, Jessica; Bianchi, Carlo Nike; Mandich, Alberta; Morri, Carla; Povero, Paolo; Wurtz, Maurizio; Melchiorre, Christian; Viano, Gianni; Cappanera, Valentina; Fanciulli, Giorgio; Bei, Massimiliano; Stasi, Nicola; Taiuti, Mauro

    2016-01-01

    Within the framework of the EU Life+ project named LIFE09 NAT/IT/000190 ARION, a permanent automated real-time passive acoustic monitoring system for the improvement of the conservation status of the transient and resident population of bottlenose dolphin (Tursiops truncatus) has been implemented and installed in the Portofino Marine Protected Area (MPA), Ligurian Sea. The system is able to detect the simultaneous presence of dolphins and boats in the area and to give their position in real time. This information is used to prevent collisions by diffusing warning messages to all the categories involved (tourists, professional fishermen and so on). The system consists of two gps-synchronized acoustic units, based on a particular type of marine buoy (elastic beacon), deployed about 1 km off the Portofino headland. Each one is equipped with a four-hydrophone array and an onboard acquisition system which can record the typical social communication whistles emitted by the dolphins and the sound emitted by boat engines. Signals are pre-filtered, digitized and then broadcast to the ground station via wi-fi. The raw data are elaborated to get the direction of the acoustic target to each unit, and hence the position of dolphins and boats in real time by triangulation. PMID:26789265

  11. On the use of photothermal techniques for monitoring constructed wetlands

    NASA Astrophysics Data System (ADS)

    Gatts, C. E. N.; Faria, R. T.; Vargas, H.; Lannes, L. S.; Aragon, G. T.; Ovalle, A. R. C.

    2003-01-01

    Wetlands are a valued part of landscapes throughout the world. The steady increase of industrial facilities and disorganized urbanization processes, especially in developing countries, became a serious menace to these systems. The capability of wetlands to serve as a sink for nonpoint pollutants, particularly nutrients, is remarkable, but not limitless. For this reason, efforts to preserve them are considered a strategic issue for several countries. In addition, due to the exploding costs for sewage treatment, constructed wetlands for wastewater treatment (reed-bed systems) have been widely used under a variety of different conditions. Wetlands present unique characteristics related to biogeochemical cycles, the transport and transformation of chemicals due to interrelated physical, and chemical, and biological processes. Particularly, vegetated wetlands can act as a source for greenhouse gases through the emission of sediment-produced methane (CH4) to atmosphere. From studies concerning the behavior of Salvinia auriculata Aublet., we intend to demonstrate the potential use of photothermal techniques for monitoring gaseous emissions in wetlands.

  12. Once Established, What Techniques Work Best for Monitoring the District?

    ERIC Educational Resources Information Center

    Triverio, Louis E.

    Monitoring school budget expenditures is as important as budgeting. School boards should decide which broad financial policies will provide control of expenditures, what financial tools to use in monitoring expenditures, and what areas outside of the budget should be monitored. A board's financial policy ought to deal with the line item transfers,…

  13. Real-time monitoring of acoustic linear and nonlinear behavior of titanium alloys during low-cycle fatigue and high-cycle fatigue

    NASA Astrophysics Data System (ADS)

    Frouin, Jerome; Sathish, Shamachary; Na, Jeong K.

    2000-05-01

    An in-situ technique to measure sound velocity, ultrasonic attenuation and acoustic nonlinear property has been developed for characterization and early detection of fatigue damage in aerospace materials. For this purpose we have developed a computer software and measurement technique including hardware for the automation of the measurement. New transducer holder and special grips are designed. The automation has allowed us to test the long-term stability of the electronics over a period of time and so proof of the linearity of the system. Real-time monitoring of the material nonlinearity has been performed on dog-bone specimens from zero fatigue all the way to the final fracture under low-cycle fatigue test condition (LCF) and high-cycle test condition (HCF). Real-time health monitoring of the material can greatly contribute to the understanding of material behavior under cyclic loading. Interpretation of the results show that correlation exist between the slope of the curve described by the material nonlinearity and the life of the component. This new methodology was developed with an objective to predict the initiation of fatigue microcracks, and to detect, in-situ fatigue crack initiation as well as to quantify early stages of fatigue damage.

  14. Acoustic monitoring of gas emissions from the seafloor. Part II: a case study from the Sea of Marmara

    NASA Astrophysics Data System (ADS)

    Bayrakci, Gaye; Scalabrin, Carla; Dupré, Stéphanie; Leblond, Isabelle; Tary, Jean-Baptiste; Lanteri, Nadine; Augustin, Jean-Marie; Berger, Laurent; Cros, Estelle; Ogor, André; Tsabaris, Christos; Lescanne, Marc; Géli, Louis

    2014-09-01

    A rotating, acoustic gas bubble detector, BOB (Bubble OBservatory) module was deployed during two surveys, conducted in 2009 and 2011 respectively, to study the temporal variations of gas emissions from the Marmara seafloor, along the North Anatolian Fault zone. The echosounder mounted on the instrument insonifies an angular sector of 7° during a given duration (of about 1 h). Then it rotates to the next, near-by angular sector and so forth. When the full angular domain is insonified, the "pan and tilt system" rotates back to its initial position, in order to start a new cycle (of about 1 day). The acoustic data reveal that gas emission is not a steady process, with observed temporal variations ranging between a few minutes and 24 h (from one cycle to the other). Echo-integration and inversion performed on the acoustic data as described in the companion paper of Leblond et al. (Mar Geophys Res, 2014), also indicate important variations in, respectively, the target strength and the volumetric flow rates of individual sources. However, the observed temporal variations may not be related to the properties of the gas source only, but reflect possible variations in sea-bottom currents, which could deviate the bubble train towards the neighboring sector. During the 2011 survey, a 4-component ocean bottom seismometer (OBS) was co-located at the seafloor, 59 m away from the BOB module. The acoustic data from our rotating, monitoring system support, but do not provide undisputable evidence to confirm, the hypothesis formulated by Tary et al. (2012), that the short-duration, non-seismic micro-events recorded by the OBS are likely produced by gas-related processes within the near seabed sediments. Hence, the use of a multibeam echosounder, or of several split beam echosounders should be preferred to rotating systems, for future experiments.

  15. 77 FR 24228 - Condition Monitoring Techniques for Electric Cables Used in Nuclear Power Plants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-23

    ... COMMISSION Condition Monitoring Techniques for Electric Cables Used in Nuclear Power Plants AGENCY: Nuclear... Techniques for Electric Cables Used in Nuclear Power Plants.'' This guide describes techniques that the staff of the NRC considers acceptable for condition monitoring of electric cables for nuclear power...

  16. The determination of acoustic reflection coefficients by using cepstral techniques, I: Experimental procedures and measurements of polyurethane foam

    NASA Astrophysics Data System (ADS)

    Bolton, J. S.; Gold, E.

    1986-10-01

    The authors have previously outlined a transient free field technique, based on cepstral analysis, for the measurement of acoustic reflection coefficients. In this paper are described laboratory acoustical measurements of the normal incidence reflection coefficient of an absorbent material: emphasis is placed on practical aspects of the technique. Specifically, the origin of extraction noise, which distorts the reflector impulse response as it appears in the power cepstrum, is discussed and means of reducing it are described and implemented. Secondly, a means of identifying and removing the time delay introduced when the reflector impulse response is copied from the cepstrum is described; this procedure eliminates the need for highly accurate measurements of path length difference. The absorbent material tested was a commercial partially reticulated polyurethane foam. Bonded to one side of the foam was an impermeable polyurethane membrane, and the foam was measured in two configurations: first with its film covered face uppermost, then with its uncovered face uppermost. The broad frequency range of the measurements made possible by the cepstral technique has given a good picture of the properties of this material. These results will be considered in detail in a subsequent publication.

  17. Acoustic Monitor for Liquid-Solid Slurries Measurements at Low Weight Fractions

    SciTech Connect

    Dr. L.L. Tavlarides; Dr. A.S. Sangan

    2004-12-08

    The principle objective of the project was to develop an acoustic probe for determining the weight fraction of particles in a flowing suspension. The suspension can be solid-liquid (S-L) or solid-gas-liquid (S-G-L). The work accomplished during the first three years of DOE funding was devoted to the development of a rigorous theory for acoustic wave propagation through solid-liquid (S-L) and solid-gas-liquid (S-G-L). In the first funding period we developed an acoustic probe for S-G-L suspensions that has resulted in a theory, supported by our experiments, to describe small amplitude acoustic wave propagations in dilute suspensions (Norato, 1999; Spelter al., 1999, 2001: Norato et al. 2002). The theory agrees well with experimental data of sound attenuation over a wide range of particle sizes, frequencies, and weight percent solids. We have also completed theoretical and experimental investigation on the effect of entrained gas bubbles on the attenuation. This analysis permits us to determine the S-L weight percent in the presence of bubbles.

  18. Performance evaluation of an acoustic indoor localization system based on a fingerprinting technique

    NASA Astrophysics Data System (ADS)

    Aloui, Nadia; Raoof, Kosai; Bouallegue, Ammar; Letourneur, Stephane; Zaibi, Sonia

    2014-12-01

    We present an acoustic location system that adopts the time of arrival of the path of maximum amplitude as a signature and estimates the target position through nonparametric kernel regression. The system was evaluated in experiments for two main configurations: a privacy-oriented configuration with code division multiple access operation and a centralized configuration with time division multiple access operation. The effects of the number and positions of sources on the performance of the privacy-oriented system was studied. Moreover, the effect of the number of fingerprint positions on the performance of both systems was investigated. Results showed that our privacy-oriented scheme provides an accuracy of 8.5 cm with 87% precision, whereas our centralized system provides an accuracy of 2.7 cm for 93% of measurements. A comparison between our privacy-oriented system and another acoustic location system based on code division multiple access operation and lateration was conducted on our test bench and revealed that the cumulative error distribution function of the fingerprint-based system is better than that of the lateration-based system. This result is similar to that found for Wi-Fi radio-based localization. However, our experiments are the first to demonstrate the detrimental effect that reverberation has on naive acoustic localization approaches.

  19. Passive acoustic monitoring to detect spawning in large-bodied catostomids

    USGS Publications Warehouse

    Straight, Carrie A.; Freeman, Byron J.; Freeman, Mary C.

    2014-01-01

    Documenting timing, locations, and intensity of spawning can provide valuable information for conservation and management of imperiled fishes. However, deep, turbid or turbulent water, or occurrence of spawning at night, can severely limit direct observations. We have developed and tested the use of passive acoustics to detect distinctive acoustic signatures associated with spawning events of two large-bodied catostomid species (River Redhorse Moxostoma carinatum and Robust Redhorse Moxostoma robustum) in river systems in north Georgia. We deployed a hydrophone with a recording unit at four different locations on four different dates when we could both record and observe spawning activity. Recordings captured 494 spawning events that we acoustically characterized using dominant frequency, 95% frequency, relative power, and duration. We similarly characterized 46 randomly selected ambient river noises. Dominant frequency did not differ between redhorse species and ranged from 172.3 to 14,987.1 Hz. Duration of spawning events ranged from 0.65 to 11.07 s, River Redhorse having longer durations than Robust Redhorse. Observed spawning events had significantly higher dominant and 95% frequencies than ambient river noises. We additionally tested software designed to automate acoustic detection. The automated detection configurations correctly identified 80–82% of known spawning events, and falsely indentified spawns 6–7% of the time when none occurred. These rates were combined over all recordings; rates were more variable among individual recordings. Longer spawning events were more likely to be detected. Combined with sufficient visual observations to ascertain species identities and to estimate detection error rates, passive acoustic recording provides a useful tool to study spawning frequency of large-bodied fishes that displace gravel during egg deposition, including several species of imperiled catostomids.

  20. Use of Modal Acoustic Emission to Monitor Damage Progression in Carbon Fiber/Epoxy Tows and Implications for Composite Structures

    NASA Technical Reports Server (NTRS)

    Waller, Jess M.; Saulsberry, Regor L.; Nichols, Charles T.; Wentzel, Daniel J.

    2010-01-01

    This slide presentation reviews the use of Modal Acoustic Emission to monitor damage progression to carbon fiber/epoxy tows. There is a risk for catastrophic failure of composite overwrapped pressure vessels (COPVs) due to burst-before-leak (BBL) stress rupture (SR) failure of carbon-epoxy (C/Ep) COPVs. A lack of quantitative nondestructive evaluation (NDE) is causing problems in current and future spacecraft designs. It is therefore important to develop and demonstrate critical NDE that can be implemented during stages of the design process since the observed rupture can occur with little of no advanced warning. Therefore a program was required to develop quantitative acoustic emission (AE) procedures specific to C/Ep overwraps, but which also have utility for monitoring damage accumulation in composite structure in general, and to lay the groundwork for establishing critical thresholds for accumulated damage in composite structures, such as COPVs, so that precautionary or preemptive engineering steps can be implemented to minimize of obviate the risk of catastrophic failure. A computed Felicity Ratio (FR) coupled with fast Fourier Transform (FFT) frequency analysis shows promise as an analytical pass/fail criterion. The FR analysis and waveform and FFT analysis are reviewed

  1. Application of a Lamb waves based technique for structural health monitoring of GFRP undercyclic loading

    NASA Astrophysics Data System (ADS)

    Eremin, A.; Byakov, A.; Panin, S.; Burkov, M.; Lyubutin, P.; Sunder, R.

    2016-04-01

    A Lamb wave based ultrasonic technique as well as optical image characterization was utilized to estimate a current mechanical state of glass fiber reinforced polymers (GFRP) under cyclic tension. The ultrasonic acoustic method was applied in a 'pitch-catch' mode using piezoelectric transducers adhesively bonded onto a specimen surface. Numerical evaluation of acoustic data was performed by calculating two informative parameters: maximum of amplitude of the received signal and variance of signal envelopes. Optical images were registered and then analysed by calculating Shannon entropy that makes it possible to characterize changing of GFRP specimen translucency. The obtained results were treated in order to find out the relation between the current mechanical state of a specimen and informative parameter values being computed from the acoustic and optical signals.

  2. A quality monitor and monitoring technique employing optically stimulated electron emission

    NASA Technical Reports Server (NTRS)

    Yost, William T. (Inventor); Welch, Christopher S. (Inventor); Joe, Edmond J. (Inventor); Hefner, Bill Bryan, Jr. (Inventor)

    1995-01-01

    A light source directs ultraviolet light onto a test surface and a detector detects a current of photoelectrons generated by the light. The detector includes a collector which is positively biased with respect to the test surface. Quality is indicated based on the photoelectron current. The collector is then negatively biased to replace charges removed by the measurement of a nonconducting substrate to permit subsequent measurements. Also, the intensity of the ultraviolet light at a particular wavelength is monitored and the voltage of the light source varied to maintain the light a constant desired intensity. The light source is also cooled via a gas circulation system. If the test surface is an insulator, the surface is bombarded with ultraviolet light in the presence of an electron field to remove the majority of negative charges from the surface. The test surface is then exposed to an ion field until it possesses no net charge. The technique described above is then performed to assess quality.

  3. Application of Condition-Based Monitoring Techniques for Remote Monitoring of a Simulated Gas Centrifuge Enrichment Plant

    SciTech Connect

    Hooper, David A; Henkel, James J; Whitaker, Michael

    2012-01-01

    This paper presents research into the adaptation of monitoring techniques from maintainability and reliability (M&R) engineering for remote unattended monitoring of gas centrifuge enrichment plants (GCEPs) for international safeguards. Two categories of techniques are discussed: the sequential probability ratio test (SPRT) for diagnostic monitoring, and sequential Monte Carlo (SMC or, more commonly, particle filtering ) for prognostic monitoring. Development and testing of the application of condition-based monitoring (CBM) techniques was performed on the Oak Ridge Mock Feed and Withdrawal (F&W) facility as a proof of principle. CBM techniques have been extensively developed for M&R assessment of physical processes, such as manufacturing and power plants. These techniques are normally used to locate and diagnose the effects of mechanical degradation of equipment to aid in planning of maintenance and repair cycles. In a safeguards environment, however, the goal is not to identify mechanical deterioration, but to detect and diagnose (and potentially predict) attempts to circumvent normal, declared facility operations, such as through protracted diversion of enriched material. The CBM techniques are first explained from the traditional perspective of maintenance and reliability engineering. The adaptation of CBM techniques to inspector monitoring is then discussed, focusing on the unique challenges of decision-based effects rather than equipment degradation effects. These techniques are then applied to the Oak Ridge Mock F&W facility a water-based physical simulation of a material feed and withdrawal process used at enrichment plants that is used to develop and test online monitoring techniques for fully information-driven safeguards of GCEPs. Advantages and limitations of the CBM approach to online monitoring are discussed, as well as the potential challenges of adapting CBM concepts to safeguards applications.

  4. Dislodgement and removal of dust-particles from a surface by a technique combining acoustic standing wave and airflow.

    PubMed

    Chen, Di; Wu, Junru

    2010-01-01

    It is known that there are many fine particles on the moon and Mars. Their existence may cause risk for the success of a long-term project for NASA, i.e., exploration and habitation of the moon and Mars. These dust-particles might cover the solar panels, making them fail to generate electricity, and they might also penetrate through seals on space suits, hatches, and vehicle wheels causing many incidents. The fine particles would be hazardous to human health if they were inhaled. Development of robust dust mitigation technology is urgently needed for the viable long-term exploration and habilitation of either the moon or Mars. A feasibility study to develop a dust removal technique, which may be used in space-stations or other enclosures for habitation, is reported. It is shown experimentally that the acoustic radiation force produced by a 13.8 kHz 128 dB sound-level standing wave between a 3 cm-aperture tweeter and a reflector separated by 9 cm is strong enough to overcome the van der Waals adhesive force between the dust-particles and the reflector-surface. Thus the majority of fine particles (>2 microm diameter) on a reflector-surface can be dislodged and removed by a technique combining acoustic levitation and airflow methods. The removal efficiency deteriorates for particles of less than 2 microm in size.

  5. Localization of quenches and mechanical disturbances in the Mu2e transport solenoid prototype using acoustic emission technique

    DOE PAGES

    Marchevsky, M.; Ambrosio, G.; Lamm, M.; Tartaglia, M. A.; Lopes, M. L.

    2016-02-12

    Acoustic emission (AE) detection is a noninvasive technique allowing the localization of the mechanical events and quenches in superconducting magnets. Application of the AE technique is especially advantageous in situations where magnet integrity can be jeopardized by the use of voltage taps or inductive pickup coils. As the prototype module of the transport solenoid (TS) for the Mu2e experiment at Fermilab represents such a special case, we have developed a dedicated six-channel AE detection system and accompanying software aimed at localizing mechanical events during the coil cold testing. The AE sensors based on transversely polarized piezoceramic washers combined with cryogenicmore » preamplifiers were mounted at the outer surface of the solenoid aluminum shell, with a 60° angular step around the circumference. Acoustic signals were simultaneously acquired at a rate of 500 kS/s, prefiltered and sorted based on their arrival time. Next, based on the arrival timing, angular and axial coordinates of the AE sources within the magnet structure were calculated. Furthermore, we present AE measurement results obtained during cooldown, spot heater firing, and spontaneous quenching of the Mu2e TS module prototype and discuss their relevance for mechanical stability assessment and quench localization.« less

  6. Dislodgement and removal of dust-particles from a surface by a technique combining acoustic standing wave and airflow.

    PubMed

    Chen, Di; Wu, Junru

    2010-01-01

    It is known that there are many fine particles on the moon and Mars. Their existence may cause risk for the success of a long-term project for NASA, i.e., exploration and habitation of the moon and Mars. These dust-particles might cover the solar panels, making them fail to generate electricity, and they might also penetrate through seals on space suits, hatches, and vehicle wheels causing many incidents. The fine particles would be hazardous to human health if they were inhaled. Development of robust dust mitigation technology is urgently needed for the viable long-term exploration and habilitation of either the moon or Mars. A feasibility study to develop a dust removal technique, which may be used in space-stations or other enclosures for habitation, is reported. It is shown experimentally that the acoustic radiation force produced by a 13.8 kHz 128 dB sound-level standing wave between a 3 cm-aperture tweeter and a reflector separated by 9 cm is strong enough to overcome the van der Waals adhesive force between the dust-particles and the reflector-surface. Thus the majority of fine particles (>2 microm diameter) on a reflector-surface can be dislodged and removed by a technique combining acoustic levitation and airflow methods. The removal efficiency deteriorates for particles of less than 2 microm in size. PMID:20058949

  7. A novel imaging technique based on the spatial coherence of backscattered waves: demonstration in the presence of acoustical clutter

    NASA Astrophysics Data System (ADS)

    Dahl, Jeremy J.; Pinton, Gianmarco F.; Lediju, Muyinatu; Trahey, Gregg E.

    2011-03-01

    In the last 20 years, the number of suboptimal and inadequate ultrasound exams has increased. This trend has been linked to the increasing population of overweight and obese individuals. The primary causes of image degradation in these individuals are often attributed to phase aberration and clutter. Phase aberration degrades image quality by distorting the transmitted and received pressure waves, while clutter degrades image quality by introducing incoherent acoustical interference into the received pressure wavefront. Although significant research efforts have pursued the correction of image degradation due to phase aberration, few efforts have characterized or corrected image degradation due to clutter. We have developed a novel imaging technique that is capable of differentiating ultrasonic signals corrupted by acoustical interference. The technique, named short-lag spatial coherence (SLSC) imaging, is based on the spatial coherence of the received ultrasonic wavefront at small spatial distances across the transducer aperture. We demonstrate comparative B-mode and SLSC images using full-wave simulations that include the effects of clutter and show that SLSC imaging generates contrast-to-noise ratios (CNR) and signal-to-noise ratios (SNR) that are significantly better than B-mode imaging under noise-free conditions. In the presence of noise, SLSC imaging significantly outperforms conventional B-mode imaging in all image quality metrics. We demonstrate the use of SLSC imaging in vivo and compare B-mode and SLSC images of human thyroid and liver.

  8. A Non-Intrusive GMA Welding Process Quality Monitoring System Using Acoustic Sensing

    PubMed Central

    Cayo, Eber Huanca; Alfaro, Sadek Crisostomo Absi

    2009-01-01

    Most of the inspection methods used for detection and localization of welding disturbances are based on the evaluation of some direct measurements of welding parameters. This direct measurement requires an insertion of sensors during the welding process which could somehow alter the behavior of the metallic transference. An inspection method that evaluates the GMA welding process evolution using a non-intrusive process sensing would allow not only the identification of disturbances during welding runs and thus reduce inspection time, but would also reduce the interference on the process caused by the direct sensing. In this paper a nonintrusive method for weld disturbance detection and localization for weld quality evaluation is demonstrated. The system is based on the acoustic sensing of the welding electrical arc. During repetitive tests in welds without disturbances, the stability acoustic parameters were calculated and used as comparison references for the detection and location of disturbances during the weld runs. PMID:22399990

  9. Program for Continued Development and Use of Ocean Acoustic/GPS Geodetic Techniques

    NASA Technical Reports Server (NTRS)

    Spiess, Fred N.

    1997-01-01

    Under prior NASA grants our group, with collaboration from scientists at the CalTech Jet Propulsion Lab (JPL), visualized and carried out the initial development of a combined GPS and underwater acoustic (GPS/A) method for determining the location of points on the deep sea floor with accuracy relevant to studies of crustal deformation. Under an immediately preceding grant we built, installed and surveyed a set of the necessary seafloor marker precision transponders just seaward of the Cascadia Subduction Zone off British Columbia. The JPL group carried out processing of the GPS data.

  10. Application of pulse compression signal processing techniques to electromagnetic acoustic transducers for noncontact thickness measurements and imaging

    SciTech Connect

    Ho, K.S.; Gan, T.H.; Billson, D.R.; Hutchins, D.A.

    2005-05-15

    A pair of noncontact Electromagnetic Acoustic Transducers (EMATs) has been used for thickness measurements and imaging of metallic plates. This was performed using wide bandwidth EMATs and pulse-compression signal processing techniques, using chirp excitation. This gives a greatly improved signal-to-noise ratio for air-coupled experiments, increasing the speed of data acquisition. A numerical simulation of the technique has confirmed the performance. Experimental results indicate that it is possible to perform noncontact ultrasonic imaging and thickness gauging in a wide range of metal plates. An accuracy of up to 99% has been obtained for aluminum, brass, and copper samples. The resolution of the image obtained using the pulse compression approach was also improved compared to a transient pulse signal from conventional pulser(receiver). It is thus suggested that the combination of EMATs and pulse compression can lead to a wide range of online applications where fast time acquisition is required.

  11. Acoustic Monitoring of Plasma Arcs in Direct Current Electric Arc Furnaces

    NASA Astrophysics Data System (ADS)

    Burchell, J. J.; Aldrich, C.; Eksteen, J. J.; Niesler, T. R.; Jemwa, G. T.

    2009-12-01

    In this article, the extraction of features from acoustic signals generated by a 60-kW direct current electric arc furnace and the use of these features to infer the arc length of the plasma jets in the furnace were considered. A sensor capable of such measurements would be more robust to the unobservable fluctuations of the arc length and would, in principle, allow better control of smelting operations. The collected data comprised sets of five separate 10-second recordings of the acoustic signal, furnace current, and voltage, each at nominal arc lengths of 5, 15, and 25 mm. In the approach, time-frequency features initially were obtained through filter bank analysis of the signals. Reduction of the dimensionality of these filter bank features was then performed using a nonlinear subspace method called kernel Fisher discriminant analysis. Finally, kernel discriminant features were used to infer the arc length via a nearest neighbor classification model that associated three classes of arc lengths (5, 15, and 25 mm) with their corresponding features. The results of the small number of experiments suggest that a significant statistical relationship exists between the length of a plasma arc and its acoustic signal despite potentially large variations in arc phenomena inside the furnace.

  12. Monitoring microbe-induced physical property changes using high-frequency acoustic waveform data: Toward the development of a microbial megascope

    SciTech Connect

    Williams, Kenneth Hurst

    2002-05-20

    A laboratory investigation was undertaken to determine the effect of microbe generated gas bubbles in controlled, saturated sediment columns utilizing a novel technique involving acoustic wave propagation. Specifically, the effect of denitrifying bacteria on saturated flow conditions was evaluated in light of the stimulated production of N{sub 2} gas and the resulting plugging of the pore throats. The propagation of high frequency acoustic waves through the sediment columns was used to locate those regions in the column where gas accumulation occurred. Over a period of six weeks, regions of gas accumulation resulted in the attenuation of acoustic wave energies with the decreases in amplitude typically greater than one order of magnitude.

  13. Detection of explosive events by monitoring acoustically-induced geomagnetic perturbations

    SciTech Connect

    Lewis, J P; Rock, D R; Shaeffer, D L; Warshaw, S I

    1999-10-07

    The Black Thunder Coal Mine (BTCM) near Gillette, Wyoming was used as a test bed to determine the feasibility of detecting explosion-induced geomagnetic disturbances with ground-based induction magnetometers. Two magnetic observatories were fielded at distances of 50 km and 64 km geomagnetically north from the northernmost edge of BTCM. Each observatory consisted of three separate but mutually orthogonal magnetometers, Global Positioning System (GPS) timing, battery and solar power, a data acquisition and storage system, and a three-axis seismometer. Explosions with yields of 1 to 3 kT of TNT equivalent occur approximately every three weeks at BTCM. We hypothesize that explosion-induced acoustic waves propagate upward and interact collisionally with the ionosphere to produce ionospheric electron density (and concomitant current density) perturbations which act as sources for geomagnetic disturbances. These disturbances propagate through an ionospheric Alfven waveguide that we postulate to be leaky (due to the imperfectly conducting lower ionospheric boundary). Consequently, wave energy may be observed on the ground. We observed transient pulses, known as Q-bursts, with pulse widths about 0.5 s and with spectral energy dominated by the Schumann resonances. These resonances appear to be excited in the earth-ionosphere cavity by Alfven solitons that may have been generated by the explosion-induced acoustic waves reaching the ionospheric E and F regions and that subsequently propagate down through the ionosphere to the atmosphere. In addition, we observe late time (> 800 s) ultra low frequency (ULF) geomagnetic perturbations that appear to originate in the upper F region ({approximately}300 km) and appear to be caused by the explosion-induced acoustic wave interacting with that part of the ionosphere. We suggest that explosion-induced Q-bursts may be discriminated from naturally occurring Q-bursts by association of the former with the late time explosion-induced ULF

  14. Debonding damage analysis in composite-masonry strengthening systems with polymer- and mortar-based matrix by means of the acoustic emission technique

    NASA Astrophysics Data System (ADS)

    Verstrynge, E.; Wevers, M.; Ghiassi, B.; Lourenço, P. B.

    2016-01-01

    Different types of strengthening systems, based on fiber reinforced materials, are under investigation for external strengthening of historic masonry structures. A full characterization of the bond behavior and of the short- and long-term failure mechanisms is crucial to ensure effective design, compatibility with the historic substrate and durability of the strengthening solution. Therein, non-destructive techniques are essential for bond characterization, durability assessment and on-site condition monitoring. In this paper, the acoustic emission (AE) technique is evaluated for debonding characterization and localization on fiber reinforced polymer (FRP) and steel reinforced grout-strengthened clay bricks. Both types of strengthening systems are subjected to accelerated ageing tests under thermal cycles and to single-lap shear bond tests. During the reported experimental campaign, AE data from the accelerated ageing tests demonstrated the thermal incompatibility between brick and epoxy-bonded FRP composites, and debonding damage was successfully detected, characterized and located. In addition, a qualitative comparison is made with digital image correlation and infrared thermography, in view of efficient on-site debonding detection.

  15. CONTINUOUS PERFORMANCE MONITORING TECHNIQUES FOR HAZARDOUS WASTE INCINERATORS

    EPA Science Inventory

    The report describes a study to determine the feasibility of utilizing realtime continuous exhaust measurements of combustion intermediates as a way to monitor incinerator performance. The key issue was to determine if a direct correlation exists between destruction efficiency (D...

  16. Pulsed-laser excitation of acoustic modes in open high-Q photoacoustic resonators for trace gas monitoring: results for C2H4

    NASA Astrophysics Data System (ADS)

    Brand, Christian; Winkler, Andreas; Hess, Peter; Miklós, András; Bozóki, Zoltán; Sneider, János

    1995-06-01

    The pulsed excitation of acoustic resonances was studied with a continuously monitoring photoacoustic detector system. Acoustic waves were generated in C2H4/N 2 gas mixtures by light absorption of the pulses from a transversely excited atmospheric CO2 laser. The photoacoustic part consisted of high-Q cylindrical resonators (Q factor 820 for the first radial mode in N2) and two adjoining variable acoustic filter systems. The time-resolved signal was Fourier transformed to a frequency spectrum of high resolution. For the first radial mode a Lorentzian profile was fitted to the measured data. The outside noise suppression and the signal-to-noise ratio were investigated in a normal laboratory environment in the flow-through mode. The acoustic and electric filter system combined with the

  17. Investigation of Various Wind Turbine Drivetrain Condition Monitoring Techniques (Presentation)

    SciTech Connect

    Sheng, S.

    2011-08-01

    This presentation was given at the 2011 Wind Turbine Reliability Workshop sponsored by Sandia National Laboratories in Albuquerque, NM on August 2-3, 2011. It discusses work for the Gearbox Reliability Collaborative including downtime caused by turbine subsystems, annual failure frequency of turbine subsystems, cost benefits of condition monitoring (CM), the Gearbox Reliability Collaborative's condition monitoring approach and rationale, test setup, and results and observations.

  18. Remote Sensing Techniques as a Tool for Environmental Monitoring

    NASA Astrophysics Data System (ADS)

    Faisal, K.; AlAhmad, M.; Shaker, A.

    2012-07-01

    The disposal of the solid wastes in landfill sites should be properly monitored by analyzing samples from soil, water, and landfill gases within the landfill site. Nevertheless, ground monitoring systems require intensive efforts and cost. Furthermore, ground monitoring may be difficult to be achieved in large geographic extent. Remote sensing technology has been introduced for waste disposal management and monitoring effects of the landfill sites on the environment. In this paper, two case studies are presented in the Trail Road landfill, Ottawa, Canada and the Al-Jleeb landfill, Al-Farwanyah, Kuwait to evaluate the use of multi-temporal remote sensing images to monitor the landfill sites. The work objectives are: 1) to study the usability of multi-temporal Landsat images for landfill site monitoring by studying the land surface temperature (LST) in the Trail Road landfill, 2) to investigate the relationship between the LST and the amount of the landfill gas emitted in the Trail Road landfill, and 3) to use the multi-temporal LST images to detect the suspicious dumping areas within the Al-Jleeb landfill site. Free archive of multi-temporal Landsat images are obtained from the USGS EarthExplorer. The Landsat images are then atmospherically corrected and the LST images are derived from the thermal band of the corrected Landsat images. In the Trail Road landfill, the results reveal that the LST of the landfill site is always higher than the air temperature by 10°C in average as well as the surroundings. A correlation is also observed between the recorded emitted methane (CH4) from the ground monitoring stations and the LST derived from the Landsat images. Based on the findings in the Al-Jleeb landfill, five locations are identified as suspicious dumping areas by overlaying the highest LST contours generated from the multi-temporal LST images. The study demonstrates that the use of multi-temporal remote sensing images can provide supplementary information for

  19. Catheter-based acoustic interrogation device for real-time monitoring of the dynamics of the lower esophageal sphincter: in vitro and pilot canine studies.

    PubMed

    Lu, Qian; Zhang, Lili; Zhao, Chunshan; Jin, Hong; Wang, Bangmao; Yadid-Pecht, Orly; Sadowski, Daniel C; Mintchev, Martin P

    2015-12-01

    This paper presents a novel minimally-invasive catheter-based acoustic interrogation device for real-time monitoring the dynamics of the lower esophageal sphincter (LES). Dysfunction of the LES could result gastrointestinal (GI) diseases, such as gastroesophageal reflux disease (GERD). A micro-oscillator actively emitting sound wave at 16 kHz is located at one side of the LES, and a miniature microphone is located at the other side of the LES to capture the sound generated from the oscillator. Thus, the dynamics of the opening and closing of the LES can be monitored. The device was tested in vitro by utilizing a custom-designed LES simulator, as well as in vivo in a pilot canine model. In the in vitro test, the sound was captured by the microphone and its strength was correlated with the level of LES opening and closing which was controlled by the simulator. The measurements showed statistically significant (p  <  0.05) Pearson correlation coefficients (0.905 on the average in quiet environment and 0.736 on the average in noisy environment, DOF  =  9). In the in vivo test, the LES was forced open and closed by a transoral endoscope, which was monitored in real-time by a transpyloric endoscope inserted from the duodenum and positioned into the distal stomach. Frame-by-frame video analysis validated the interrelation between the sound strength and the LES opening and closing. The LES dynamics monitored by the proposed device has the potential to become a valuable minimally-invasive technique for understanding LES dysfunction.

  20. Acoustic emission descriptors

    NASA Astrophysics Data System (ADS)

    Witos, Franciszek; Malecki, Ignacy

    The authors present selected problems associated with acoustic emission interpreted as a physical phenomenon and as a measurement technique. The authors examine point sources of acoustic emission in isotropic, homogeneous linearly elastic media of different shapes. In the case of an unbounded medium the authors give the analytical form of the stress field and the wave shift field of the acoustic emission. In the case of a medium which is unbounded plate the authors give a form for the equations which is suitable for numerical calculation of the changes over time of selected acoustic emission values. For acoustic emission as a measurement technique, the authors represent the output signal as the resultant of a mechanical input value which describes the source, the transient function of the medium, and the transient function of specific components of the measurement loop. As an effect of this notation, the authors introduce the distinction between an acoustic measurement signal and an acoustic measurement impulse. The authors define the basic parameters of an arbitrary impulse. The authors extensively discuss the signal functions of acoustic emission impulses and acoustic emission signals defined in this article as acoustic emission descriptors (or signal functions of acoustic emission impulses) and advanced acoustic emission descriptors (which are either descriptors associated with acoustic emission applications or the signal functions of acoustic emission signals). The article also contains the results of experimental research on three different problems in which acoustic emission descriptors associated with acoustic emission pulses, acoustic emission applications, and acoustic emission signals are used. These problems are respectively: a problem of the amplitude-load characteristics of acoustic emission pulses in carbon samples subjected to compound uniaxial compression, the use of acoustic emission to predict the durability characteristics of conveyor belts, and

  1. Coupling creep and damage in concrete under high sustained loading: Experimental investigation on bending beams and application of Acoustic Emission technique

    NASA Astrophysics Data System (ADS)

    Saliba, J.; Loukili, A.; Grondin, F.

    2010-06-01

    effect on concrete, probably because of the consolidation of the hardened cement paste. The influence of creep on fracture energy, fracture toughness, and characteristic length of concrete is also studied. The fracture energy and the characteristic length of concrete increases slightly when creep occurs prior to failure and the size of the fracture process zone increases too. The load-CMOD relationship is linear in the ascending portion and gradually drops off after the peak value in the descending portion. The length of the tail end portion of the softening curve increases with beams subjected to creep. Relatively more ductile fracture behavior was observed with beams subjected to creep. The contribution of non-destructive and instrumental investigation methods is currently exploited to check and measure the evolution of some negative structural phenomena, such as micro-and macro-cracking, finally resulting in a creep-like behaviour. Among these methods, the non-destructive technique based on acoustic Emission proves to be very effective, especially to check and measure micro-cracking that takes place inside a structure under mechanical loading. Thus as a part of the investigation quantitative acoustic emission techniques were applied to investigate microcracking and damage localization in concrete beams. The AE signals were captured with the AE WIN software and further analyzed with Noesis software analysis of acoustic emission data. AE waveforms were generated as elastic waves in concrete due to crack nucleation. And a multichannel data acquisition system was used to record the AE waveforms. During the three point bending tests, quantitative acoustic emission (AE) techniques were used to monitor crack growth and to deduce micro fracture mechanics in concrete beams before and after creep. Several specimens are experimented in order to match each cluster with corresponding damage mechanism of the material under loading. At the same time acoustic emission was used to

  2. Evaluation of change detection techniques for monitoring coastal zone environments

    NASA Technical Reports Server (NTRS)

    Weismiller, R. A. (Principal Investigator); Kristof, S. J.; Scholz, D. K.; Anuta, P. E.; Momin, S. M.

    1977-01-01

    The author has identified the following significant results. Four change detection techniques were designed and implemented for evaluation: (1) post classification comparison change detection, (2) delta data change detection, (3) spectral/temporal change classification, and (4) layered spectral/temporal change classification. The post classification comparison technique reliably identified areas of change and was used as the standard for qualitatively evaluating the other three techniques. The layered spectral/temporal change classification and the delta data change detection results generally agreed with the post classification comparison technique results; however, many small areas of change were not identified. Major discrepancies existed between the post classification comparison and spectral/temporal change detection results.

  3. Development of interactive digital scientific acoustic systems for monitoring and assessment of physical and biological variables from ocean observatory platforms

    NASA Astrophysics Data System (ADS)

    McClure, Robert; Acker, Tim; Dawson, James; Ebrahim, Assad E. K.

    2005-04-01

    Scientific echosounders are in regular use for measurement of fish and plankton distribution and abundance, fish behavior, submersed aquatic vegetation, bottom sediment classification and water mass interface characteristics. Both fixed-aspect and mobile acoustic data are commonly collected from surface-deployed echosounders. Advancements in digital scientific echosounder technology and integration of other technologies has moved the capabilities of advanced echosounder systems into the realm of new applications and deployment possibilities. These advancements make possible the deployment of a new generation of integrated and interactive sensors which can provide high resolution, continuous, extended duration, recording, intelligent processing, and reliable monitoring and assessment of both biological and physical parameters of the ocean environment. Deployments from cabled observatories, moored and drifting buoys, manned and unmanned mobile platforms, and fully autonomous installations are all now reality. The deployment of these quality scientific instrument suites hold unlimited potential for research, resource management, and education. Existing and planned implementation of advanced digital scientific echosounder applications on observatories as well as considerations in design, deployment, and integration with other observatory and oceanic acoustic activities are discussed.

  4. Passive acoustic monitoring using a towed hydrophone array results in identification of a previously unknown beaked whale habitat.

    PubMed

    Yack, Tina M; Barlow, Jay; Calambokidis, John; Southall, Brandon; Coates, Shannon

    2013-09-01

    Beaked whales are diverse and species rich taxa. They spend the vast majority of their time submerged, regularly diving to depths of hundreds to thousands of meters, typically occur in small groups, and behave inconspicuously at the surface. These factors make them extremely difficult to detect using standard visual survey methods. However, recent advancements in acoustic detection capabilities have made passive acoustic monitoring (PAM) a viable alternative. Beaked whales can be discriminated from other odontocetes by the unique characteristics of their echolocation clicks. In 2009 and 2010, PAM methods using towed hydrophone arrays were tested. These methods proved highly effective for real-time detection of beaked whales in the Southern California Bight (SCB) and were subsequently implemented in 2011 to successfully detect and track beaked whales during the ongoing Southern California Behavioral Response Study. The three year field effort has resulted in (1) the successful classification and tracking of Cuvier's (Ziphius cavirostris), Baird's (Berardius bairdii), and unidentified Mesoplodon beaked whale species and (2) the identification of areas of previously unknown beaked whale habitat use. Identification of habitat use areas will contribute to a better understanding of the complex relationship between beaked whale distribution, occurrence, and preferred habitat characteristics on a relatively small spatial scale. These findings will also provide information that can be used to promote more effective management and conservation of beaked whales in the SCB, a heavily used Naval operation and training region.

  5. Results obtained during acoustic emission monitoring of proof testing of a large Kevlar/epoxy rocket motor case

    SciTech Connect

    Hamstad, M.A.

    1982-12-01

    A total of 15 acoustic emission (AE) sensors were used to monitor a large Kevlar 49/epoxy rocket motor case during proof cycles to successively higher levels. Fourteen of the sensors were placed on the composite surface and one sensor was coupled to a stainless steel waveguide which penetrated the full length of the inside of the hydraulically pressurized motor case. To reduce signal propagation losses, the bandpass was chosen to be 5 to 10 kHz. In addition to an Acoustic Emission Technology (AET) 5000 system, Hewlett Packard 3400 A root-mean-square voltmeters, and a 1010 Biomation transient recorder were used to record AE data. The AET system measured rise time, event duration, peak amplitude, and energy (calculated from event duration and peak amplitude) for each AE event. The main purpose of this paper is to present and discuss the AE data obtained by hand post-processing of event listings generated for each proof cycle of the AE data taped by the 5000 system during the test. Real AE signal propagation losses are compared to the losses from Pentel pencil-lead breaks. We present first-hit sensor data for events with high amplitude, energy, and event duration. This data indicated that a certain area of the composite case is the potential region of failure.

  6. Detection and Processing Techniques of FECG Signal for Fetal Monitoring

    PubMed Central

    2009-01-01

    Fetal electrocardiogram (FECG) signal contains potentially precise information that could assist clinicians in making more appropriate and timely decisions during labor. The ultimate reason for the interest in FECG signal analysis is in clinical diagnosis and biomedical applications. The extraction and detection of the FECG signal from composite abdominal signals with powerful and advance methodologies are becoming very important requirements in fetal monitoring. The purpose of this review paper is to illustrate the various methodologies and developed algorithms on FECG signal detection and analysis to provide efficient and effective ways of understanding the FECG signal and its nature for fetal monitoring. A comparative study has been carried out to show the performance and accuracy of various methods of FECG signal analysis for fetal monitoring. Finally, this paper further focused some of the hardware implementations using electrical signals for monitoring the fetal heart rate. This paper opens up a passage for researchers, physicians, and end users to advocate an excellent understanding of FECG signal and its analysis procedures for fetal heart rate monitoring system. PMID:19495912

  7. Latch-up signature analysis technique for plastic dual-in-line package (PDIP) devices using scanning acoustic microscopy

    SciTech Connect

    Mahanpour, M.; Morgan, I.; Li, S.; Kaufmann, M.

    1995-12-31

    Cracks in the top surface of plastic package product (PDIP), as shown in a figure, resulting from Latch-Up (LU), DC Vcc Over-Voltage, or Reverse Insertion in the socket are usually similar in appearance. A scanning acoustic microscope can not determine the root cause of this Electrical Over-Stress (EOS) damage since all of the above show similar delamination. Even after device decapsulation, carbonized epoxy around Vcc and Vss bond wires doesn`t always indicate the exact root cause of failure. However, a nondestructive technique has been developed to distinguish (LU) from other EOS failures using a Scanning Acoustic Microscope (SAM). Finally, to verify the validity of the results, a computer analysis using a 3-Dimensional Finite Element Model (FEM) was used. The calculated stress distribution in the plastic IC package in the sustained LU condition agreed with the observations of delamination using SAM on product subjected to Transient Latch-Up (TLU) simulation on the power supply pin.

  8. Monitoring co- and pre-seismic motion by geodetic techniques

    NASA Astrophysics Data System (ADS)

    Groten, E.

    1992-02-01

    A recently built extensometer, which is based on a highly stable capacitance transducer, as well as a liquid bubble Hughes tiltmeter are discussed in view of monitoring strain and deformations at the Earth's surface. These instruments are being used to control local variations, whereas regional and global changes, including gravity variations, are monitored using repeated GPS and very precise relative gravimetry. With sufficient exterior control (such as absolute gravimetry for calibration, tidal measurements for separating tidal from other effects) we will acquire a more or less complete system (in combination with local leveling etc. as used by several other authors as well) for determination of time-dependent phenomena.

  9. Assessment of the application of acoustic emission technology for monitoring the presence of sand under multiphase flow condition

    SciTech Connect

    El-Alej, M. Mba, D. Yeung, H.

    2014-04-11

    The monitoring of multiphase flow is an established process that has spanned several decades. This paper demonstrates the use of acoustic emission (AE) technology to investigate sand transport characteristic in three-phase (air-water-sand) flow in a horizontal pipe where the superficial gas velocity (VSG) had a range of between 0.2 ms{sup −1} to 2.0 ms{sup −1} and superficial liquid velocity (VSL) had a range of between 0.2 ms{sup −1} to 1.0 ms{sup −1}. The experimental findings clearly show a correlation exists between AE energy levels, sand concentration, superficial gas velocity (VSG) and superficial liquid velocity (VSL)

  10. Acoustic Transmitters for Underwater Neutrino Telescopes

    PubMed Central

    Ardid, Miguel; Martínez-Mora, Juan A.; Bou-Cabo, Manuel; Larosa, Giuseppina; Adrián-Martínez, Silvia; Llorens, Carlos D.

    2012-01-01

    In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars), high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing received signals. Secondly, a compact acoustic transmitter array has been developed for the calibration of acoustic neutrino detection systems. The array is able to mimic the signature of ultra-high-energy neutrino interaction in emission directivity and signal shape. The technique of parametric acoustic sources has been used to achieve the proposed aim. The developed compact array has practical features such as easy manageability and operation. The prototype designs and the results of different tests are described. The techniques applied for these two acoustic systems are so powerful and versatile that may be of interest in other marine applications using acoustic transmitters. PMID:22666022

  11. Acoustic transmitters for underwater neutrino telescopes.

    PubMed

    Ardid, Miguel; Martínez-Mora, Juan A; Bou-Cabo, Manuel; Larosa, Giuseppina; Adrián-Martínez, Silvia; Llorens, Carlos D

    2012-01-01

    In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars), high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing received signals. Secondly, a compact acoustic transmitter array has been developed for the calibration of acoustic neutrino detection systems. The array is able to mimic the signature of ultra-high-energy neutrino interaction in emission directivity and signal shape. The technique of parametric acoustic sources has been used to achieve the proposed aim. The developed compact array has practical features such as easy manageability and operation. The prototype designs and the results of different tests are described. The techniques applied for these two acoustic systems are so powerful and versatile that may be of interest in other marine applications using acoustic transmitters.

  12. Microwave rotational spectroscopy: A physical technique for specific pollutant monitoring

    NASA Technical Reports Server (NTRS)

    Hrubesh, L. W.

    1973-01-01

    An attempt was made to present substantial evidence that microwave rotational spectroscopy can be developed for use in air pollution monitoring. Work with the diode-cavity spectrometer shows it to be capable to detecting small concentrations on NO2, SO2, H2,CO, and NH3 gas with very high specificity.

  13. An investigation of the solidification of a metal and two n-paraffins using an acoustic technique.

    NASA Technical Reports Server (NTRS)

    Bailey, J. A.; Davila, J. R.

    1971-01-01

    A novel acoustic technique is described for following the motion of the solid-liquid interface during the freezing of mercury, n-hexadecane and n-octadecane where heat transfer is unidirectional. It is shown that the actual amount of solidification occurring in a given time differs from that predicted using a numerical solution to the transient heat conduction problem. The differences are small for mercury but large for the paraffins. They are interpreted in terms of the nature of the solid-liquid interface. Furthermore the experimental and predicted temperature distributions in the liquid and solid phases differ. These differences are extremely small for mercury. The data for the three materials conform to a relationship observed previously according to which the thickness of the solidified layer is a linear function of the square root of time.

  14. Acoustic emission frequency discrimination

    NASA Technical Reports Server (NTRS)

    Sugg, Frank E. (Inventor); Graham, Lloyd J. (Inventor)

    1988-01-01

    In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.

  15. AN EVALUATION OF CONDITION MONITORING TECHNIQUES FOR LOW-VOLTAGE ELECTRIC CABLES

    SciTech Connect

    LOFARO,R.J.; GROVE,E.; SOO,P.

    2000-07-23

    Aging of systems and components in nuclear power plants is a well known occurrence that must be managed to ensure the continued safe operation of these plants. Much of the degradation due to aging is controlled through periodic maintenance and/or component replacement. However, there are components that do not receive periodic maintenance or monitoring once they are installed; electric cables are such a component. To provide a means of monitoring the condition of electric cables, research is ongoing to evaluate promising condition monitoring (CM) techniques that can be used in situ to monitor cable condition and predict remaining life. While several techniques are promising, each has limitations that must be considered in its application. This paper discusses the theory behind several of the promising cable CM techniques being studied, along with their effectiveness for monitoring aging degradation in typical cable insulation materials, such as cross-linked polyethylene and ethylene propylene rubber. Successes and limitations of each technique are also presented.

  16. A new strategy toward Internet of Things: structural health monitoring using a combined fiber optic and acoustic emission wireless sensor platform

    NASA Astrophysics Data System (ADS)

    Nguyen, A. D.; Page, C.; Wilson, C. L.

    2016-04-01

    This paper investigates a new low-power structural health monitoring (SHM) strategy where fiber Bragg grating (FBG) rosettes can be used to continuously monitor for changes in a host structure's principal strain direction, suggesting damage and thus enabling the immediate triggering of a higher power acoustic emissions (AE) sensor to provide for better characterization of the damage. Unlike traditional "always on" AE platforms, this strategy has the potential for low power, while the wireless communication between different sensor types supports the Internet of Things (IoT) approach. A combination of fiber-optic sensor rosettes for strain monitoring and a fiber-optic sensor for acoustic emissions monitoring was attached to a sample and used to monitor crack initiation. The results suggest that passive principal strain direction monitoring could be used as a damage initiation trigger for other active sensing elements such as acoustic emissions. In future work, additional AE sensors can be added to provide for damage location; and a strategy where these sensors can be powered on periodically to further establish reliability while preserving an energy efficient scheme can be incorporated.

  17. Biological water quality monitoring using chemiluminescent and bioluminescent techniques

    NASA Technical Reports Server (NTRS)

    Thomas, R. R.

    1978-01-01

    Automated chemiluminescence and bioluminescence sensors were developed for the continuous monitoring of microbial levels in water supplies. The optimal chemical procedures were determined for the chemiluminescence system to achieve maximum sensitivity. By using hydrogen peroxide, reaction rate differentiation, ethylene diamine tetraacetic acid (EDTA), and carbon monoxide pretreatments, factors which cause interference were eliminated and specificity of the reaction for living and dead bacteria was greatly increased. By employing existing technology with some modifications, a sensitive and specific bioluminescent system was developed.

  18. Intensive sound speed monitoring in ocean and its impact on the GPS/acoustic seafloor geodetic measurement

    NASA Astrophysics Data System (ADS)

    Kido, Motoyuki

    2016-04-01

    GPS/acoustic (GPS/A) technique, based on GPS positioning and acoustic ranging, is now getting a popular tool to measure seafloor crustal movement. Several groups in the world have been intensively conducted campaign surveys in the region of scientifically interest. As the technology of measurement has been matured and plenty of data are accumulated, researchers are now aware of the limit of its precision mainly due to unexpected undulation of sound speed in ocean, which significantly degrades acoustic ranging. If sound speed structure keeps its figure during survey period, e.g., more than a couple of hours, it can be estimated by a moving survey to get sufficient paths from various directions to illustrate the structure. However the sound speed structure often varies quickly with in a hour due to internal gravitational wave excited by interaction of tidal current and seafloor topography. In this case one cannot separate temporal and spatial variations. We revisited our numerous sound speed profile data derived from numbers of XBT measurements, which were concurrently carried out with GPS/A survey along the Nankai Trough and Japan Trench. Among the measurements, we found notably short-period variation in sound speed profile through intensive XBT survey repeatedly cast every 6 minutes for one hour, which also appeared in residuals in traveltime of acoustic ranging. The same feature is also found in more moderate rate for semidiurnal undulation, in which vertical oscillation of the middle of the profile can be clearly seen rather than variation of absolute sound speed. This also reflects traveltime residuals in the GPS/A measurement. These typical frequencies represent dominant wavelengths of spatial sound speed variation. In the latter, local horizontal variation can be negligible in the vicinity of a point survey area and the traditional analysis can be applicable that assumes time-varying stratified sound speed structure. In the former case, on the contrary, local

  19. Acoustic puncture assist device: A novel technique to identify the epidural space

    PubMed Central

    Al-Mokaddam, MA; Al-Harbi, MK; El-Jandali, ST; Al-Zahrani, TA

    2016-01-01

    Background: Acoustic puncture assist device (APAD) is designed to detect and signal the loss of resistance during the epidural procedure. We aimed to evaluate this device in terms of successful identification of the epidural space and the incidence of accidental dural puncture. Patients and Methods: Following Institutional Review Board approval and written informed consent obtained from all patients, 200 adult patients (107 males) American Society of Anesthesiologists I-III who underwent lower limb orthopedic surgery under lumbar epidural anesthesia using APAD were enrolled in the study. APAD system was connected to the epidural needle using normal saline prefilled extension tube. Numbers of successful epidural attempts and accidental dural tap were documented. Results: The mean values of the depth of epidural space and the time to perform epidural puncture were 5.8 ± 1.0 cm and 3.3 ± 1.4 min, respectively. In 63% of patients, epidural puncture was successful from the first attempt and in 1% it was successful from the fourth attempt. Epidural anesthesia by APAD was successful in 198 cases (99 %). Dural tap occurred in 2 cases (1%). Conclusions: Using APAD, the success of identifying the epidural space was high and reliable. PMID:27051369

  20. Development of Methodology to Assess the Failure Behaviour of Bamboo Single Fibre by Acoustic Emission Technique

    NASA Astrophysics Data System (ADS)

    Alam, Md. Saiful; Gulshan, Fahmida; Ahsan, Qumrul; Wevers, Martine; Pfeiffer, Helge; van Vuure, Aart-Willem; Osorio, Lina; Verpoest, Ignaas

    2016-06-01

    Acoustic emission (AE) was used as a tool for detecting, evaluating and for better understanding of the damage mechanism and failure behavior in composites during mechanical loading. Methodology was developed for tensile test of natural fibres (bamboo single fibre). A series of experiments were performed and load drops (one or two) were observed in the load versus time graphs. From the observed AE parameters such as amplitude, energy, duration etc. significant information corresponding to the load drops were found. These AE signals from the load drop occurred from such failure as debonding between two elementary fibre or from join of elementary fibre at edge. The various sources of load at first load drop was not consistent for the different samples (for a particular sample the value is 8 N, stress: 517.51 MPa). Final breaking of fibre corresponded to saturated level AE amplitude of preamplifier (99.9 dB) for all samples. Therefore, it was not possible to determine the exact AE energy value for final breaking. Same methodology was used for tensile test of three single fibres, which gave clear indication of load drop before the final breaking of first and second fibre.

  1. Use of Modal Acoustic Emission to Monitor Damage Progression in Carbon Fiber/epoxy Composites

    NASA Astrophysics Data System (ADS)

    Waller, J. M.; Nichols, C. T.; Wentzel, D. J.; Saulsberry, R. L.

    2011-06-01

    Broad-band modal acoustic emission (AE) was used to characterize micromechanical damage progression in uniaxial IM7 and T1000 carbon fiber-epoxy (C/Ep) tows, and a helical and hoop-wrapped IM7 composite overwrapped pressure vessel (COPV). To expedite analysis, tows and the COPV were subjected to an intermittent load hold tensile stress profile. Damage progression in tow specimens was followed by analyzing the Fast Fourier Transforms (FFTs) associated with AE events. FFT analysis showed that damage was usually cooperative, consisting of several failure modes occurring at once, and was dominated by fiber breakage throughout the duration of the stress profile. Evidence was found for the existence of a universal damage parameter, referred to here as the critical Felicity ratio, or Felicity ratio at rupture (FR*), which had a value close to 0.96 for the tows and the COPV tested. The use of FR* to predict the burst pressure of the COPV is demonstrated.

  2. Acoustic Modifications of the Ames 40x80 Foot Wind Tunnel and Test Techniques for High-Speed Research Model Testing

    NASA Technical Reports Server (NTRS)

    Soderman, Paul T.; Olson, Larry (Technical Monitor)

    1995-01-01

    The NFAC 40- by 80- Foot Wind Tunnel at Ames is being refurbished with a new, deep acoustic lining in the test section which will make the facility nearly anechoic over a large frequency range. The modification history, key elements, and schedule will be discussed. Design features and expected performance gains will be described. Background noise reductions will be summarized. Improvements in aeroacoustic research techniques have been developed and used recently at NFAC on several wind tunnel tests of High Speed Research models. Research on quiet inflow microphones and struts will be described. The Acoustic Survey Apparatus in the 40x80 will be illustrated. A special intensity probe was tested for source localization. Multi-channel, high speed digital data acquisition is now used for acoustics. And most important, phased microphone arrays have been developed and tested which have proven to be very powerful for source identification and increased signal-to-noise ratio. Use of these tools for the HEAT model will be illustrated. In addition, an acoustically absorbent symmetry plane was built to satisfy the HEAT semispan aerodynamic and acoustic requirements. Acoustic performance of that symmetry plane will be shown.

  3. Measurement of velocity distribution for longitudinal acoustic waves in welds by a laser optoacoustic technique

    NASA Astrophysics Data System (ADS)

    Ivochkin, A. Yu.; Karabutov, A. A.; Lyamshev, M. L.; Pelivanov, I. M.; Rohatgi, U.; Subudhi, M.

    2007-07-01

    An optoacoustic technique for diagnostics of residual stress in metals is proposed. The theoretical part of the technique employs acoustoelastic relations establishing a linear relationship between the biaxial residual stress and the relative variation of the velocity of longitudinal ultrasonic waves. The experimental technique is based on laser excitation of nanosecond ultrasonic pulses at the surface of samples under investigation and their detection with a high time resolution. Distributions of the relative variation of longitudinal wave velocities due to the presence of residual stress in the samples are obtained.

  4. Numerical techniques in linear duct acoustics. [finite difference and finite element analyses

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.

    1980-01-01

    Both finite difference and finite element analyses of small amplitude (linear) sound propagation in straight and variable area ducts with flow, as might be found in a typical turboject engine duct, muffler, or industrial ventilation system, are reviewed. Both steady state and transient theories are discussed. Emphasis is placed on the advantages and limitations associated with the various numerical techniques. Examples of practical problems are given for which the numerical techniques have been applied.

  5. Techniques and results of nongame bird monitoring in North America

    USGS Publications Warehouse

    Robbins, C.S.; Bystrak, D.; Geissler, P.H.; Oelke, H.

    1980-01-01

    Long-term bird population trends based on accumulated ratios (proportional change) sometimes give a very misleading view of population change. Alternate methods of representing population change, based on the weighted means for the individual years, avoid the dangers of using ratios. Some advantages and disadvantages of various weighting techniques are discussed.

  6. In Situ Techniques for Monitoring Electrochromism: An Advanced Laboratory Experiment

    ERIC Educational Resources Information Center

    Saricayir, Hakan; Uce, Musa; Koca, Atif

    2010-01-01

    This experiment employs current technology to enhance and extend existing lab content. The basic principles of spectroscopic and electroanalytical techniques and their use in determining material properties are covered in some detail in many undergraduate chemistry programs. However, there are limited examples of laboratory experiments with in…

  7. Tunnel monitoring with an advanced InSAR technique

    NASA Astrophysics Data System (ADS)

    Rabus, Bernhard; Eppler, Jayson; Sharma, Jayanti; Busler, Jennifer

    2012-06-01

    The detection and monitoring of subsurface excavations has a variety of applications in both the civil and defense domains. We have developed a novel InSAR method (Homogenous Distributed Scatterer (HDS)-InSAR) that exploits both persistent point and coherent distributed scatterers by using adaptive multilooking of statistically homogenous pixel neighborhoods. In order to enhance the detection of small scale structures in low SNR environments a matched parametric spatio-temporal model is fit to the deformation signal. We illustrate the performance of our new method for the city of Vancouver over the last nine years using InSAR stacks of RADARSAT-1 and RADARSAT-2 data.

  8. Molecularly Imprinted Polymer Integrated with a Surface Acoustic Wave Technique for Detection of Sulfamethizole.

    PubMed

    Ayankojo, Akinrinade George; Tretjakov, Aleksei; Reut, Jekaterina; Boroznjak, Roman; Öpik, Andres; Rappich, Jörg; Furchner, Andreas; Hinrichs, Karsten; Syritski, Vitali

    2016-01-19

    The synergistic effect of combining molecular imprinting and surface acoustic wave (SAW) technologies for the selective and label-free detection of sulfamethizole as a model antibiotic in aqueous environment was demonstrated. A molecularly imprinted polymer (MIP) for sulfamethizole (SMZ) selective recognition was prepared in the form of a homogeneous thin film on the sensing surfaces of SAW chip by oxidative electropolymerization of m-phenylenediamine (mPD) in the presence of SMZ, acting as a template. Special attention was paid to the rational selection of the functional monomer using computational and spectroscopic approaches. SMZ template incorporation and its subsequent release from the polymer was supported by IR microscopic measurements. Precise control of the thicknesses of the SMZ-MIP and respective nonimprinted reference films (NIP) was achieved by correlating the electrical charge dosage during electrodeposition with spectroscopic ellipsometry measurements in order to ensure accurate interpretation of label-free responses originating from the MIP modified sensor. The fabricated SMZ-MIP films were characterized in terms of their binding affinity and selectivity toward the target by analyzing the binding kinetics recorded using the SAW system. The SMZ-MIPs had SMZ binding capacity approximately more than eight times higher than the respective NIP and were able to discriminate among structurally similar molecules, i.e., sulfanilamide and sulfadimethoxine. The presented approach for the facile integration of a sulfonamide antibiotic-sensing layer with SAW technology allowed observing the real-time binding events of the target molecule at nanomolar concentration levels and could be potentially suitable for cost-effective fabrication of a multianalyte chemosensor for analysis of hazardous pollutants in an aqueous environment. PMID:26704414

  9. Molecularly Imprinted Polymer Integrated with a Surface Acoustic Wave Technique for Detection of Sulfamethizole.

    PubMed

    Ayankojo, Akinrinade George; Tretjakov, Aleksei; Reut, Jekaterina; Boroznjak, Roman; Öpik, Andres; Rappich, Jörg; Furchner, Andreas; Hinrichs, Karsten; Syritski, Vitali

    2016-01-19

    The synergistic effect of combining molecular imprinting and surface acoustic wave (SAW) technologies for the selective and label-free detection of sulfamethizole as a model antibiotic in aqueous environment was demonstrated. A molecularly imprinted polymer (MIP) for sulfamethizole (SMZ) selective recognition was prepared in the form of a homogeneous thin film on the sensing surfaces of SAW chip by oxidative electropolymerization of m-phenylenediamine (mPD) in the presence of SMZ, acting as a template. Special attention was paid to the rational selection of the functional monomer using computational and spectroscopic approaches. SMZ template incorporation and its subsequent release from the polymer was supported by IR microscopic measurements. Precise control of the thicknesses of the SMZ-MIP and respective nonimprinted reference films (NIP) was achieved by correlating the electrical charge dosage during electrodeposition with spectroscopic ellipsometry measurements in order to ensure accurate interpretation of label-free responses originating from the MIP modified sensor. The fabricated SMZ-MIP films were characterized in terms of their binding affinity and selectivity toward the target by analyzing the binding kinetics recorded using the SAW system. The SMZ-MIPs had SMZ binding capacity approximately more than eight times higher than the respective NIP and were able to discriminate among structurally similar molecules, i.e., sulfanilamide and sulfadimethoxine. The presented approach for the facile integration of a sulfonamide antibiotic-sensing layer with SAW technology allowed observing the real-time binding events of the target molecule at nanomolar concentration levels and could be potentially suitable for cost-effective fabrication of a multianalyte chemosensor for analysis of hazardous pollutants in an aqueous environment.

  10. Novel Monitoring Techniques for Characterizing Frictional Interfaces in the Laboratory

    PubMed Central

    Selvadurai, Paul A.; Glaser, Steven D.

    2015-01-01

    A pressure-sensitive film was used to characterize the asperity contacts along a polymethyl methacrylate (PMMA) interface in the laboratory. The film has structural health monitoring (SHM) applications for flanges and other precision fittings and train rail condition monitoring. To calibrate the film, simple spherical indentation tests were performed and validated against a finite element model (FEM) to compare normal stress profiles. Experimental measurements of the normal stress profiles were within −7.7% to 6.6% of the numerical calculations between 12 and 50 MPa asperity normal stress. The film also possessed the capability of quantifying surface roughness, an important parameter when examining wear and attrition in SHM applications. A high definition video camera supplied data for photometric analysis (i.e., the measure of visible light) of asperities along the PMMA-PMMA interface in a direct shear configuration, taking advantage of the transparent nature of the sample material. Normal stress over individual asperities, calculated with the pressure-sensitive film, was compared to the light intensity transmitted through the interface. We found that the luminous intensity transmitted through individual asperities linearly increased 0.05643 ± 0.0012 candelas for an increase of 1 MPa in normal stress between normal stresses ranging from 23 to 33 MPa. PMID:25923930

  11. Novel monitoring techniques for characterizing frictional interfaces in the laboratory.

    PubMed

    Selvadurai, Paul A; Glaser, Steven D

    2015-01-01

    A pressure-sensitive film was used to characterize the asperity contacts along a polymethyl methacrylate (PMMA) interface in the laboratory. The film has structural health monitoring (SHM) applications for flanges and other precision fittings and train rail condition monitoring. To calibrate the film, simple spherical indentation tests were performed and validated against a finite element model (FEM) to compare normal stress profiles. Experimental measurements of the normal stress profiles were within -7.7% to 6.6% of the numerical calculations between 12 and 50 MPa asperity normal stress. The film also possessed the capability of quantifying surface roughness, an important parameter when examining wear and attrition in SHM applications. A high definition video camera supplied data for photometric analysis (i.e., the measure of visible light) of asperities along the PMMA-PMMA interface in a direct shear configuration, taking advantage of the transparent nature of the sample material. Normal stress over individual asperities, calculated with the pressure-sensitive film, was compared to the light intensity transmitted through the interface. We found that the luminous intensity transmitted through individual asperities linearly increased 0.05643 ± 0.0012 candelas for an increase of 1 MPa in normal stress between normal stresses ranging from 23 to 33 MPa. PMID:25923930

  12. Semi-real-time monitoring of cracking on couplings by neural network analysis of acoustic emission signals

    NASA Astrophysics Data System (ADS)

    Godinez-Azcuaga, Valery F.; Shu, Fong; Finlayson, Richard D.; O'Donnell, Bruce W.

    2004-07-01

    This paper presents the results obtained during the development of a semi-real-time monitoring methodology based on Neural Network Pattern Recognition of Acoustic Emission (AE) signals for early detection of cracks in couplings used in aircraft and engine drive systems. AE signals were collected in order to establish a baseline of a gear-testing fixture background noise and its variations due to rotational speed and torque. Also, simulated cracking signals immersed in background noise were collected. EDM notches were machined in the driving gear and the load on the gearbox was increased until damaged was induced. Using these data, a Neural Network Signal Classifier (NNSC) was implemented and tested. The testing showed that the NNSC was capable of correctly identifying six different classes of AE signals corresponding to different gearbox operation conditions. Also, a semi-real-time classification software was implemented. This software includes functions that allow the user to view and classify AE data from a dynamic process as they are recorded at programmable time intervals. The software is capable of monitoring periodic statistics of AE data, which can be used as an indicator of damage presence and severity in a dynamic system. The semi-real-time classification software was successfully tested in situations where a delay of 10 seconds between data acquisition and classification was achieved with a hit rate of 50 hits/second per channel on eight active AE channels.

  13. MR-monitored focused ultrasound using the acoustic-coupling water bath as an intrinsic high-mode dielectric resonator.

    PubMed

    Webb, A G

    2014-06-01

    The conventional set-up for MR-monitored focused ultrasound surgery includes a piezoelectric transducer and an acoustic-coupling water bath integrated into the MR patient table; a large surface RF coil is placed close to the patient or, alternatively, the body coil is used as the MR receiver. Potential disadvantages of this approach are that the body coil has low sensitivity because of its low filling factor and the local RF coil can interfere with and cause reflections of the ultrasound irradiation. In this article, a completely new approach is presented, in which an MR transmit/receive coil is not needed at all. Instead, the dimensions of the water bath are adjusted so that a high-order dielectric mode is excited, resulting in efficient MR excitation and reception at the transducer focal point. An example of monitoring ultrasound-mediated heating in a phantom is shown on a 7-T human system, although the new method can also be applied at lower fields. PMID:24737389

  14. Development of optical systems. [holographic technique for monitoring crystal growth

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.

    1995-01-01

    Several key aspects of multi-color holography and laser speckle technique to study holographic reconstructions are considered in the report. Holographic fringe contrast in two-color holography in the presence of a fluid cell in the object beam is discussed in detail. A specific example of triglycine sulfate crystal growth is also considered. A breadboard design using fiber optics and diode lasers for three-color holography for fluid experiments is presented. A possible role of multi-color holography in various new applications is summarized. Finally, the use of a a laser speckle technique is demonstrated for the study of holographic reconstructions. The demonstration is performed using a Spacelab 3 hologram.

  15. Monitoring disease in lymphoma and CLL patients using molecular techniques.

    PubMed

    Gribben, John G

    2002-03-01

    Over the past decade considerable advances have been made in the sensitivity of detection of residual lymphoma and leukaemia cells. Assays based on the polymerase chain reaction (PCR) can detect one tumour cell in up to 10(5) to 10(6) normal cells. The identification and cloning of breakpoints associated with specific chromosomal translocations has made possible the application of these techniques to a variety of lymphoid malignancies. In parallel, B cell malignancies exhibit rearrangements of their immunoglobulin genes that are also suitable targets for PCR amplification to identify residual cells. Although these techniques provide a useful adjunct to standard methods of detection and diagnosis, their role in determining disease outcome remains investigational. There is confusion as to whether it is necessary to eradicate PCR-detectable lymphoma cells for cure, so it is not yet possible to determine whether the detection of residual lymphoma cells by PCR is an indication to continue therapy. PMID:11987923

  16. New remote sensing technique for lidar monitoring of atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Belen'kii, Mikhail S.; Gimmestad, Gary G.

    1993-09-01

    A new remote sensing technique is proposed for determining the turbulent parameters of the atmosphere using a single-ended lidar system. This technique is based on the enhanced backscattering effect and is insensitive to the scattering volume averaging effect on the intensity fluctuations of the reflected wave and the sounding beam. The corresponding measurements are independent of the turbulent scintillation spectrum and that permits the use of high power pulsed lasers with a relatively low repetition rate for determining the refractive index structure characteristic Cn2, its vertical profile Cn2(h) and inner scale of turbulence lo in the atmosphere. A theory of the method is developed, and the conditions are obtained for observing the backscattering amplification effect in the atmosphere with a laser beam scattered by aerosol. The signal-to-noise ratio and the sensitivity of the measured quantities to the inner scale of turbulence lo variations are estimated. A planned demonstration of this technique in the boundary layer of the atmosphere with an eyesafe lidar which has been developed at Georgia Tech is discussed.

  17. Color Kinesis: New Technique or Just Another Display of Acoustic Quantification?

    PubMed

    Mor-Avi, Victor; Godoy, Ivan E.; Lang, Roberto M.

    1999-01-01

    Color kinesis is a relatively new echocardiographic technique that allows color encoding of endocardial motion in real time. We briefly review the literature on the current clinical uses and limitations of this technique, as well as its potential future applications based on some of our results. The major advantage of this modality is that it provides the basis for objective and automated evaluation of regional systolic and diastolic function, which may have a direct impact on the diagnosis of various myocardial disease states and, in particular, coronary artery disease.

  18. Coffee roasting acoustics.

    PubMed

    Wilson, Preston S

    2014-06-01

    Cracking sounds emitted by coffee beans during the roasting process were recorded and analyzed to investigate the potential of using the sounds as the basis for an automated roast monitoring technique. Three parameters were found that could be exploited. Near the end of the roasting process, sounds known as "first crack" exhibit a higher acoustic amplitude than sounds emitted later, known as "second crack." First crack emits more low frequency energy than second crack. Finally, the rate of cracks appearing in the second crack chorus is higher than the rate in the first crack chorus.

  19. Opportunities for Process Monitoring Techniques at Delayed Access Facilities

    SciTech Connect

    Curtis, Michael M.; Gitau, Ernest TN; Johnson, Shirley J.; Schanfein, Mark; Toomey, Christopher

    2013-09-20

    Except for specific cases where the International Atomic Energy Agency (IAEA) maintains a continuous presence at a facility (such as the Japanese Rokkasho Reprocessing Plant), there is always a period of time or delay between the moment a State is notified or aware of an upcoming inspection, and the time the inspector actually enters the material balance area or facility. Termed by the authors as “delayed access,” this period of time between inspection notice and inspector entrance to a facility poses a concern. Delayed access also has the potential to reduce the effectiveness of measures applied as part of the Safeguards Approach for a facility (such as short-notice inspections). This report investigates the feasibility of using process monitoring to address safeguards challenges posed by delayed access at a subset of facility types.

  20. Aquatic Acoustic Metrics Interface Utility for Underwater Sound Monitoring and Analysis

    PubMed Central

    Ren, Huiying; Halvorsen, Michele B.; Deng, Zhiqun Daniel; Carlson, Thomas J.

    2012-01-01

    Fishes and marine mammals may suffer a range of potential effects from exposure to intense underwater sound generated by anthropogenic activities such as pile driving, shipping, sonars, and underwater blasting. Several underwater sound recording (USR) devices have been built to acquire samples of the underwater sound generated by anthropogenic activities. Software becomes indispensable for processing and analyzing the audio files recorded by these USRs. In this paper, we provide a detailed description of a new software package, the Aquatic Acoustic Metrics Interface (AAMI), specifically designed for analysis of underwater sound recordings to provide data in metrics that facilitate evaluation of the potential impacts of the sound on aquatic animals. In addition to the basic functions, such as loading and editing audio files recorded by USRs and batch processing of sound files, the software utilizes recording system calibration data to compute important parameters in physical units. The software also facilitates comparison of the noise sound sample metrics with biological measures such as audiograms of the sensitivity of aquatic animals to the sound, integrating various components into a single analytical frame. The features of the AAMI software are discussed, and several case studies are presented to illustrate its functionality. PMID:22969353

  1. Active monitoring of formaldehyde diffusion into histological tissues with digital acoustic interferometry.

    PubMed

    Bauer, Daniel R; Stevens, Benjamin; Chafin, David; Theiss, Abbey P; Otter, Michael

    2016-01-01

    The preservation of certain labile cancer biomarkers with formaldehyde-based fixatives can be considerably affected by preanalytical factors such as quality of fixation. Currently, there are no technologies capable of quantifying a fixative's concentration or the formation of cross-links in tissue specimens. This work examined the ability to detect formalin diffusion into a histological specimen in real time. As formaldehyde passively diffused into tissue, an ultrasound time-of-flight (TOF) shift of several nanoseconds was generated due to the distinct sound velocities of formalin and exchangeable fluid within the tissue. This signal was resolved with a developed digital acoustic interferometry algorithm, which compared the phase differential between signals and computed the absolute TOF with subnanosecond precision. The TOF was measured repeatedly across the tissue sample for several hours until diffusive equilibrium was realized. The change in TOF from 6-mm thick ex vivo human tonsil fit a single-exponential decay ([Formula: see text]) with rate constants that varied drastically spatially between 2 and 10 h ([Formula: see text]) due to substantial heterogeneity. This technology may prove essential to personalized cancer diagnostics by documenting and tracking biospecimen preanalytical fixation, guaranteeing their suitability for diagnostic assays, and speeding the workflow in clinical histopathology laboratories. PMID:26866049

  2. Aquatic acoustic metrics interface utility for underwater sound monitoring and analysis.

    PubMed

    Ren, Huiying; Halvorsen, Michele B; Deng, Zhiqun Daniel; Carlson, Thomas J

    2012-01-01

    Fishes and marine mammals may suffer a range of potential effects from exposure to intense underwater sound generated by anthropogenic activities such as pile driving, shipping, sonars, and underwater blasting. Several underwater sound recording (USR) devices have been built to acquire samples of the underwater sound generated by anthropogenic activities. Software becomes indispensable for processing and analyzing the audio files recorded by these USRs. In this paper, we provide a detailed description of a new software package, the Aquatic Acoustic Metrics Interface (AAMI), specifically designed for analysis of underwater sound recordings to provide data in metrics that facilitate evaluation of the potential impacts of the sound on aquatic animals. In addition to the basic functions, such as loading and editing audio files recorded by USRs and batch processing of sound files, the software utilizes recording system calibration data to compute important parameters in physical units. The software also facilitates comparison of the noise sound sample metrics with biological measures such as audiograms of the sensitivity of aquatic animals to the sound, integrating various components into a single analytical frame. The features of the AAMI software are discussed, and several case studies are presented to illustrate its functionality.

  3. A Dry Membrane Protection Technique to Allow Surface Acoustic Wave Biosensor Measurements of Biological Model Membrane Approaches

    PubMed Central

    Reder-Christ, Katrin; Schmitz, Patrick; Bota, Marian; Gerber, Ursula; Falkenstein-Paul, Hildegard; Fuss, Christian; Enachescu, Marius; Bendas, Gerd

    2013-01-01

    Model membrane approaches have attracted much attention in biomedical sciences to investigate and simulate biological processes. The application of model membrane systems for biosensor measurements is partly restricted by the fact that the integrity of membranes critically depends on the maintenance of an aqueous surrounding, while various biosensors require a preconditioning of dry sensors. This is for example true for the well-established surface acoustic wave (SAW) biosensor SAM®5 blue. Here, a simple drying procedure of sensor-supported model membranes is introduced using the protective disaccharide trehalose. Highly reproducible model membranes were prepared by the Langmuir-Blodgett technique, transferred to SAW sensors and supplemented with a trehalose solution. Membrane rehydration after dry incorporation into the SAW device becomes immediately evident by phase changes. Reconstituted model membranes maintain their full functionality, as indicated by biotin/avidin binding experiments. Atomic force microscopy confirmed the morphological invariability of dried and rehydrated membranes. Approximating to more physiological recognition phenomena, the site-directed immobilization of the integrin VLA-4 into the reconstituted model membrane and subsequent VCAM-1 ligand binding with nanomolar affinity were illustrated. This simple drying procedure is a novel way to combine the model membrane generation by Langmuir-Blodgett technique with SAW biosensor measurements, which extends the applicability of SAM®5 blue in biomedical sciences. PMID:24064603

  4. Damage Characterization of Glass/Epoxy Composite Under Three-Point Bending Test Using Acoustic Emission Technique

    NASA Astrophysics Data System (ADS)

    Pashmforoush, Farzad; Fotouhi, Mohamad; Ahmadi, Mehdi

    2012-07-01

    Acoustic emission (AE) technique is an efficient non-destructive method for detection and identification of various damage mechanisms in composite materials. Discrimination of AE signals related to different damage modes is of great importance in the use of this technique. For this purpose, integration of k-means algorithm and genetic algorithm (GA) was used in this study to cluster AE events of glass/epoxy composite during three-point bending test. Performing clustering analysis, three clusters with separate frequency ranges were obtained, each one representing a distinct damage mechanism. Furthermore, time-frequency analysis of AE signals was performed based on wavelet packet transform (WPT). In order to find the dominant components associated with different damage mechanisms, the energy distribution criterion was used. The frequency ranges of the dominant components were then compared with k-means genetic algorithm (KGA) outputs. Finally, SEM observation was utilized to validate the results. The obtained results indicate good performance of the proposed methods in the damage characterization of composite materials.

  5. Visualization and characterization of the acoustic radiation force assisted displacement of particles using an OCT technique (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Razani, Marjan; Zam, Azhar; Arezza, Nico J. J.; Wang, Yan J.; Kolios, Michael C.

    2016-03-01

    In this study, we present a technique to image the enhanced particle displacement generated using an acoustic radiation force (ARF) excitation source. A swept-source OCT (SS-OCT) system with a center wavelength of 1310nm, a bandwidth of ~100nm, and an A-scan rate of 100 kHz (MEMS-VCSEL OCT Thorlabs) was used to detect gold nanoparticle (70nm in diameter) displacement .ARF was applied after the nanoparticles passed through a porous membrane and diffused into a collagen (6% collagen) matrix. B-mode, M-B mode, 3D and Speckle Variance (SV) images were acquired before and after the ARF beam was on. Differential OCT speckle variance images with and without the ARF were used to measure the particle displacement. The images were used to detect the microscopic enhancement of nanoparticle displacement generated by the ARF. Using this OCT imaging technique, the extravasation of particles though a porous membrane and characterization of the enhanced particle displacement in a collagen gel after using an ARF excitation was achieved.

  6. Use of High Resolution Mobile Monitoring Techniques to Assess Near-Road Air Quality Variability

    EPA Science Inventory

    This presentation provides a description of the techniques used to develop and conduct effective mobile monitoring studies. It also provides a summary of mobile monitoring assessment studies that have been used to assess near-road concentrations and the variability of pollutant l...

  7. Use of High Resolution Mobile Monitoring Techniques to Assess Near Road Air Quality Variability

    EPA Science Inventory

    This presentation provides a description of the techniques used to develop and conduct effective mobile monitoring studies. It also provides a summary of mobile monitoring assessment studies that have been used to assess near-road concentrations and the variability of pollutant l...

  8. Shoreline Change Monitoring Using High Resolution Digital Photogrammetric Technique

    NASA Astrophysics Data System (ADS)

    Ahn, Y.; Lee, H.; Kim, K. H.; Shin, B. S.; Huh, K. I.

    2015-12-01

    Shoreline change has been measured with conventional surveying techniques such as Total station, GNSS, EDM etc. These measurements provide short/long term variation of nearshore evolution which enables us to estimate erosional and accretion sediment volume of the beach. This observation of ocean morphology currently has been utilized through the advance of optical imaging system and related digital image analysis. When deployed with proper viewing geometry, ground based digital imaging system can provide higher spatial/temporal resolution of shoreline change than satellite remote sensing data. In this study, we focus on generating time series of shore line change in Gwangan/Songjung beach in Busan, Korea where two DSLR imaging station have been successfully installed nearly at the end of each beach span. Via single photo photogrammetric techniques such as lens calibration, interior/exterior orientation, feature tracking, projection toward water surface, we aim to 1) calibrate out time lapse camera system, 2) verify with conventionally observed shorelines and finally 3) quantify the trend of ocean morphology in target sites.

  9. Bird biodiversity assessments in temperate forest: the value of point count versus acoustic monitoring protocols

    PubMed Central

    Willig, Michael R.

    2015-01-01

    Effective monitoring programs for biodiversity are needed to assess trends in biodiversity and evaluate the consequences of management. This is particularly true for birds and faunas that occupy interior forest and other areas of low human population density, as these are frequently under-sampled compared to other habitats. For birds, Autonomous Recording Units (ARUs) have been proposed as a supplement or alternative to point counts made by human observers to enhance monitoring efforts. We employed two strategies (i.e., simultaneous-collection and same-season) to compare point count and ARU methods for quantifying species richness and composition of birds in temperate interior forests. The simultaneous-collection strategy compares surveys by ARUs and point counts, with methods matched in time, location, and survey duration such that the person and machine simultaneously collect data. The same-season strategy compares surveys from ARUs and point counts conducted at the same locations throughout the breeding season, but methods differ in the number, duration, and frequency of surveys. This second strategy more closely follows the ways in which monitoring programs are likely to be implemented. Site-specific estimates of richness (but not species composition) differed between methods; however, the nature of the relationship was dependent on the assessment strategy. Estimates of richness from point counts were greater than estimates from ARUs in the simultaneous-collection strategy. Woodpeckers in particular, were less frequently identified from ARUs than point counts with this strategy. Conversely, estimates of richness were lower from point counts than ARUs in the same-season strategy. Moreover, in the same-season strategy, ARUs detected the occurrence of passerines at a higher frequency than did point counts. Differences between ARU and point count methods were only detected in site-level comparisons. Importantly, both methods provide similar estimates of species

  10. Bird biodiversity assessments in temperate forest: the value of point count versus acoustic monitoring protocols.

    PubMed

    Klingbeil, Brian T; Willig, Michael R

    2015-01-01

    Effective monitoring programs for biodiversity are needed to assess trends in biodiversity and evaluate the consequences of management. This is particularly true for birds and faunas that occupy interior forest and other areas of low human population density, as these are frequently under-sampled compared to other habitats. For birds, Autonomous Recording Units (ARUs) have been proposed as a supplement or alternative to point counts made by human observers to enhance monitoring efforts. We employed two strategies (i.e., simultaneous-collection and same-season) to compare point count and ARU methods for quantifying species richness and composition of birds in temperate interior forests. The simultaneous-collection strategy compares surveys by ARUs and point counts, with methods matched in time, location, and survey duration such that the person and machine simultaneously collect data. The same-season strategy compares surveys from ARUs and point counts conducted at the same locations throughout the breeding season, but methods differ in the number, duration, and frequency of surveys. This second strategy more closely follows the ways in which monitoring programs are likely to be implemented. Site-specific estimates of richness (but not species composition) differed between methods; however, the nature of the relationship was dependent on the assessment strategy. Estimates of richness from point counts were greater than estimates from ARUs in the simultaneous-collection strategy. Woodpeckers in particular, were less frequently identified from ARUs than point counts with this strategy. Conversely, estimates of richness were lower from point counts than ARUs in the same-season strategy. Moreover, in the same-season strategy, ARUs detected the occurrence of passerines at a higher frequency than did point counts. Differences between ARU and point count methods were only detected in site-level comparisons. Importantly, both methods provide similar estimates of species

  11. Application of X-ray imaging techniques to auroral monitoring

    NASA Technical Reports Server (NTRS)

    Rust, D. M.; Burstein, P.

    1981-01-01

    The precipitation of energetic particles into the ionosphere produces bremsstrahlung X-rays and K-alpha line emission from excited oxygen and nitrogen. If viewed from a spacecraft in a highly elliptical polar orbit, this soft (0.3 - 3.0 keV) X-radiation will provide an almost uninterrupted record of dayside and nightside auroras. A grazing incidence X-ray telescope especially designed for such auroral monitoring is described. High photon collection efficiency will permit exposure times of approximately 100 seconds during substorms. Spectrophotometry will allow users to derive the energy spectrum of the precipitating particles. If placed in a 15 earth-radius orbit, the telescope can produce auroral X-ray images with 30 km resolution. Absolute position of X-ray auroras can be established with a small optical telescope co-aligned with the X-ray telescope. Comparison of X-ray and optical images will establish the height and global distribution of X-ray aurorae, relative to well-known optical auroras, thus melding the new X-ray results with knowledge of optical auroras.

  12. The penetrometer - A technique for monitoring composite propellant ageing characteristics

    NASA Astrophysics Data System (ADS)

    Faulkner, G. S.

    The monitoring of the natural and accelerated aging of rubbery composite propellants by using a non-destructive mechanical properties tester, the 'penetrometer', is presented. This capability facilitates predictions of rocket-motor service life and also detects motors that may not have been stored correctly. The probe is inserted into the conduit of a motor and held in place by an integral, motor-specific, air-bag. The indenter is then driven into the charge in a low-stress region. Information obtained from the test is displayed graphically on a microcomputer, analyzed, and stored. It is concluded that, because not all of the rocket motors will have seen the same environment depending on the individual motor history, it will be possible to extend the lifetime before disposal since the charge can now be tested. This in turn will lead to financial savings if the charge's life can be said to have 'X' years of life left and does not need to be withdrawn from service.

  13. Pressure monitoring technique provides cost-savings solution

    SciTech Connect

    Blanchard, J.O.

    1994-05-01

    EnergyNorth Natural Gas, Inc. solved its concern over cost-effectively retrieving various amounts of data over an extensive geographical area with a smart pressure transmitter. Much of the company's existing technology was either old, or required a substantial degree of manual intervention. It was determined that the age along with manual requirements would have an adverse effect on future management operations. The company explored the market for alternative solutions and the search led to the Rosemount Model 1151 Smart Pressure Transmitter. The transmitter was particularly appealing because it allowed direct communication with the transmitter through a modem without additional peripheral devices. The supplier was contacted directly regarding the interest in using the devices for monitoring the ENGI system pressures. Specifications for the HART protocol was provided which was used to determine how to utilize the transmitters to obtain cost-effective pressure readings. The smart transmitters proved to be the driving force behind the entire SCADA system installation. The use of these transmitters will pay for SCADA installation over a 5-year period.

  14. Aerial monitoring in active mud volcano by UAV technique

    NASA Astrophysics Data System (ADS)

    Pisciotta, Antonino; Capasso, Giorgio; Madonia, Paolo

    2016-04-01

    UAV photogrammetry opens various new applications in the close range domain, combining aerial and terrestrial photogrammetry, but also introduces low-cost alternatives to the classical manned aerial photogrammetry. Between 2014 and 2015 tree aerial surveys have been carried out. Using a quadrotor drone, equipped with a compact camera, it was possible to generate high resolution elevation models and orthoimages of The "Salinelle", an active mud volcanoes area, located in territory of Paternò (South Italy). The main risks are related to the damages produced by paroxysmal events. Mud volcanoes show different cyclic phases of activity, including catastrophic events and periods of relative quiescence characterized by moderate activity. Ejected materials often are a mud slurry of fine solids suspended in liquids which may include water and hydrocarbon fluids, the bulk of released gases are carbon dioxide, with some methane and nitrogen, usually pond-shaped of variable dimension (from centimeters to meters in diameter). The scope of the presented work is the performance evaluation of a UAV system that was built to rapidly and autonomously acquire mobile three-dimensional (3D) mapping data in a volcanic monitoring scenario.

  15. Sheet resistance monitoring of low dose implants using the double implant technique

    NASA Astrophysics Data System (ADS)

    Smith, A. K.; Johnson, W. H.; Keenan, W. A.; Rigik, Michael; Kleppinger, Rob

    Sheet resistance has become an industry standard for monitoring high and medium dose ion implants. For low dose there are two sheet resistance techniques available, the direct implant technique and the double implant technique. Careful processing has extended the range of direct sheet resistance measurements down to doses of 2E11 ions/cm 2. The double implant technique requires an initial implant to create an easily measured sheet resistance layer that serves as the test vehicle for the second implant. The dose of the second implant is measured by monitoring the change in the sheet resistance due to the implant damage created by the second implant into the first. This double implant technique is not limited to low dose nor to species that are electrically active in the substrate. The sensitivity of any measurement is defined as the percent change in the measured value divided by the percent change with monitored value. The direct sheet resistance technique has a sensitivity of about unity in the low dose region. For the double implant technique, however, the sensitivity can be increased up to 1.5 by varying the initial dose. The sensitivity of the double implant technique can thus be tailored to the particular dose to be monitored. Several double implant experiments will be reviewed to demonstrate the range, repeatability, accuracy, resolution and sensitivity of the technique.

  16. Evaluation of the uranium double spike technique for environmental monitoring

    S