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Sample records for acoustic interferometry technique

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. The digital holographic interferometry in resonant acoustic spectroscopy

    International Nuclear Information System (INIS)

    GAPONOV, V.E.; AZAMATOV, Z.T.; REDKORECHEV, V.I.; ISAEV, A.M.

    2014-01-01

    The opportunities of application of digital holographic interferometry method for studies of shapes of resonant modes in resonant acoustic spectroscopy are shown. The results of experimental measurements and analytical calculations are submitted. (authors)

  3. High-contrast Nulling Interferometry Techniques Project

    Data.gov (United States)

    National Aeronautics and Space Administration — "We are developing rotating-baseline nulling-interferometry techniques and algorithms on the single-aperture Hale and Keck telescopes at near-infrared wavelengths,...

  4. Theoretical Properties of Acoustical Speckle Interferometry.

    Science.gov (United States)

    1980-09-01

    Cylinders in Water," J. Acoust. Soc. Am., 45, 1134-1144, (1969). 27. Bunney, R. E., R. R. Goodman, and S. W. Marshall, "Rayleigh and Lamb Waves on...Mechanics Research Center ATTN: DRXMR-PL I -MT, Mr. Farrow 1 Watertown, Massachusetts 02172 Commander White Sands Missile Range ATTN: STEWS -AD-L White

  5. Underwater Acoustic Networking Techniques

    CERN Document Server

    Otnes, Roald; Casari, Paolo; Goetz, Michael; Husøy, Thor; Nissen, Ivor; Rimstad, Knut; van Walree, Paul; Zorzi, Michele

    2012-01-01

    This literature study presents an overview of underwater acoustic networking. It provides a background and describes the state of the art of all networking facets that are relevant for underwater applications. This report serves both as an introduction to the subject and as a summary of existing protocols, providing support and inspiration for the development of network architectures.

  6. Acoustic techniques in nuclear safeguards

    International Nuclear Information System (INIS)

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

    1995-01-01

    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

  7. On the focusing conditions in time-reversed acoustics, seismic interferometry, and Marchenko imaging

    NARCIS (Netherlands)

    Wapenaar, C.P.A.; Van der Neut, J.R.; Thorbecke, J.W.; Vasconcelos, I.; Van Manen, D.J.; Ravasi, M.

    2014-01-01

    Despite the close links between the fields of time-reversed acoustics, seismic interferometry and Marchenko imaging, a number of subtle differences exist. This paper reviews the various focusing conditions of these methods, the causality/acausality aspects of the corresponding focusing wavefields,

  8. Thermal Cracking in Westerly Granite Monitored Using Direct Wave Velocity, Coda Wave Interferometry, and Acoustic Emissions

    Science.gov (United States)

    Griffiths, L.; Lengliné, O.; Heap, M. J.; Baud, P.; Schmittbuhl, J.

    2018-03-01

    To monitor both the permanent (thermal microcracking) and the nonpermanent (thermo-elastic) effects of temperature on Westerly Granite, we combine acoustic emission monitoring and ultrasonic velocity measurements at ambient pressure during three heating and cooling cycles to a maximum temperature of 450°C. For the velocity measurements we use both P wave direct traveltime and coda wave interferometry techniques, the latter being more sensitive to changes in S wave velocity. During the first cycle, we observe a high acoustic emission rate and large—and mostly permanent—apparent reductions in velocity with temperature (P wave velocity is reduced by 50% of the initial value at 450°C, and 40% upon cooling). Our measurements are indicative of extensive thermal microcracking during the first cycle, predominantly during the heating phase. During the second cycle we observe further—but reduced—microcracking, and less still during the third cycle, where the apparent decrease in velocity with temperature is near reversible (at 450°C, the P wave velocity is decreased by roughly 10% of the initial velocity). Our results, relevant for thermally dynamic environments such as geothermal reservoirs, highlight the value of performing measurements of rock properties under in situ temperature conditions.

  9. Interferometry

    Science.gov (United States)

    Totzeck, Michael

    The intention of this chapter is to provide a fast and comprehensive overview of the principles of interferometry and the various types of interferometer, including interferogram evaluation and applications. Due to the age and the importance of the subject, you can find a number of monographs [16.1,2,3,4] and book chapters [16.5] in the literature. The number of original papers on optical interferometry is far too large to even attempt complete coverage in this chapter. Whenever possible, review papers are cited. Original papers are cited according to their aptness as starting points into the subject. This, however, reflects my personal judgment. Even if you do not share my opinion, you should find the references therein useful.

  10. Interferometry

    Science.gov (United States)

    Ridgway, Stephen; Wilson, Robert W.; Begelman, Mitchell C.; Bender, Peter; Burke, Bernard F.; Cornwell, Tim; Drever, Ronald; Dyck, H. Melvin; Johnston, Kenneth J.; Kibblewhite, Edward

    1991-01-01

    The following recommended programs are reviewed: (1) infrared and optical interferometry (a ground-based and space programs); (2) compensation for the atmosphere with adaptive optics (a program for development and implementation of adaptive optics); and (3) gravitational waves (high frequency gravitational wave sources (LIGO), low frequency gravitational wave sources (LAGOS), a gravitational wave observatory program, laser gravitational wave observatory in space, and technology development during the 1990's). Prospects for international collaboration and related issues are also discussed.

  11. Verification of time-delay interferometry techniques using the University of Florida LISA interferometry simulator

    Energy Technology Data Exchange (ETDEWEB)

    Mitryk, Shawn J; Wand, Vinzenz; Mueller, Guido, E-mail: smitryk@phys.ufl.ed, E-mail: mueller@phys.ufl.ed [Department of Physics, University of Florida, PO Box 118440, Gainesville, FL 32611-8440 (United States)

    2010-04-21

    Laser Interferometer Space Antenna (LISA) is a cooperative NASA/ESA mission proposed to directly measure gravitational waves (GW) in the frequency range from 30 muHz to 1 Hz with an optimal strain sensitivity of 10{sup -21}/sq root(Hz) at 3 mHz. LISA will utilize a modified Michelson interferometer to measure length changes of 40 pm/sq root(Hz) between drag-free proof masses located on three separate spacecraft (SC) separated by a distance of 5 Gm. The University of Florida has developed a hardware-in-the-loop simulator of the LISA constellation to verify the laser noise cancellation technique known as time-delay interferometry (TDI). We replicate the frequency stabilization of the laser on the local SC and the phase-locking of the lasers on the far SC. The laser photodetector beatnotes are electronically delayed, Doppler shifted and applied with a mock GW signal to simulate the laser link between the SC. The beatnotes are also measured with a LISA-like phasemeter and the data are used to extract the laser phase and residual phase-lock loop noise in post-processing through TDI. This uncovers the GW modulation signal buried under the laser noise. The results are then compared to the requirements defined by the LISA science collaboration.

  12. Physically-Based Interactive Flow Visualization Based on Schlieren and Interferometry Experimental Techniques

    KAUST Repository

    Brownlee, C.; Pegoraro, V.; Shankar, S.; McCormick, Patrick S.; Hansen, C. D.

    2011-01-01

    Understanding fluid flow is a difficult problem and of increasing importance as computational fluid dynamics (CFD) produces an abundance of simulation data. Experimental flow analysis has employed techniques such as shadowgraph, interferometry

  13. Acoustic emission technique and its applications

    International Nuclear Information System (INIS)

    Sato, Ichiya; Sasaki, Soji

    1976-01-01

    Acoustic emission technique is described. The characteristics of acoustic emission signal, measurement techniques, and its application are explained. The acoustic signals are grouped into continuous and burst types. The continuous signal is due to plastic deformation, and the burst type is due to the generation and growth of cracks. The latter can be used for the identification of the position of cracks. The frequency of the acoustic emission is in the range from several tens of KHz to two MHz. Piezoelectric ceramics are used as the oscillators of sensors. The dynamic behavior of acoustic emission can be observed with a two-channel acoustic emission measuring apparatus. Multi-channel method was developed at Hitachi, Ltd., and is used for large structures. General computer identification method and simple zone identification method are explained. Noise elimination is important for the measurement, and the methods were studied. Examples of application are the observation of acoustic emission in the plastic deformation of steel, the tensile test of large welded material with natural defects, and others. The method will be used for the diagnosis and observation of large structures, the test and quality control of products. (Kato, T.)

  14. Acoustic surveillance techniques for SGU leak monitoring

    International Nuclear Information System (INIS)

    McKnight, J.A.; Rowley, R.; Beesley, M.J.

    1990-01-01

    The paper presents a brief review of the acoustic techniques applicable to the detection of steam generator unit leaks that have been studied in the UK. Before discussion of the acoustic detection methods a reference representation of the required performance as developed in the UK is given. The conclusion is made that preliminary specification for the acoustic leak detection of sodium/water leaks in steam generating units suggests that it will be necessary to detect better than a leak rate of 3 g/s within a few seconds. 10 refs, 12 figs

  15. Flaw evolution monitoring by acoustic emission technique

    International Nuclear Information System (INIS)

    Ghia, S.; Sala, A.; Lucia, A.

    1986-01-01

    Flaw evolution monitoring during mechanical fatigue test has been performed by acoustic emission (AE) technique. Testing on 1:5 reduced scale vessel containing fabrication defects was carried out in the frame of an European program for pressure component residual life evaluation. Characteristics of AE signals associated to flaw evolution are discussed

  16. Acoustic Techniques for Structural Health Monitoring

    Science.gov (United States)

    Frankenstein, B.; Augustin, J.; Hentschel, D.; Schubert, F.; Köhler, B.; Meyendorf, N.

    2008-02-01

    Future safety and maintenance strategies for industrial components and vehicles are based on combinations of monitoring systems that are permanently attached to or embedded in the structure, and periodic inspections. The latter belongs to conventional nondestructive evaluation (NDE) and can be enhanced or partially replaced by structural health monitoring systems. However, the main benefit of this technology for the future will consist of systems that can be differently designed based on improved safety philosophies, including continuous monitoring. This approach will increase the efficiency of inspection procedures at reduced inspection times. The Fraunhofer IZFP Dresden Branch has developed network nodes, miniaturized transmitter and receiver systems for active and passive acoustical techniques and sensor systems that can be attached to or embedded into components or structures. These systems have been used to demonstrate intelligent sensor networks for the monitoring of aerospace structures, railway systems, wind energy generators, piping system and other components. Material discontinuities and flaws have been detected and monitored during full scale fatigue testing. This paper will discuss opportunities and future trends in nondestructive evaluation and health monitoring based on new sensor principles and advanced microelectronics. It will outline various application examples of monitoring systems based on acoustic techniques and will indicate further needs for research and development.

  17. Actively stabilized optical fiber interferometry technique for online/in-process surface measurement

    International Nuclear Information System (INIS)

    Wang Kaiwei; Martin, Haydn; Jiang Xiangqian

    2008-01-01

    In this paper, we report the recent progress in optical-beam scanning fiber interferometry for potential online nanoscale surface measurement based on the previous research. It attempts to generate a robust and miniature measurement device for future development into a multiprobe array measurement system. In this research, both fiber-optic-interferometry and the wavelength-division-multiplexing techniques have been used, so that the optical probe and the optical interferometer are well spaced and fast surface scanning can be carried out, allowing flexibility for online measurement. In addition, this system provides a self-reference signal to stabilize the optical detection with high common-mode noise suppression by adopting an active phase tracking and stabilization technique. Low-frequency noise was significantly reduced compared with unstabilized result. The measurement of a sample surface shows an attained repeatability of 3.3 nm

  18. Laser Techniques on Acoustically Levitated Droplets

    Science.gov (United States)

    Cannuli, Antonio; Caccamo, Maria Teresa; Castorina, Giuseppe; Colombo, Franco; Magazù, Salvatore

    2018-01-01

    This work reports the results of an experimental study where laser techniques are applied to acoustically levitated droplets of trehalose aqueous solutions in order to perform spectroscopic analyses as a function of concentration and to test the theoretical diameter law. The study of such systems is important in order to better understand the behaviour of trehalose-synthesizing extremophiles that live in extreme environments. In particular, it will be shown how acoustic levitation, combined with optical spectroscopic instruments allows to explore a wide concentration range and to test the validity of the diameter law as a function of levitation lag time, i.e. the D2 vs t law. On this purpose a direct diameter monitoring by a video camera and a laser pointer was first performed; then the diameter was also evaluated by an indirect measure through an OH/CH band area ratio analysis of collected Raman and Infrared spectra. It clearly emerges that D2 vs t follows a linear trend for about 20 minutes, reaching then a plateau at longer time. This result shows how trehalose is able to avoid total water evaporation, this property being essential for the surviving of organisms under extreme environmental conditions.

  19. Beam shaping optics to enhance performance of interferometry techniques in grating manufacture

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei

    2018-02-01

    Improving of industrial holographic and interferometry techniques is of great importance in interference lithography, computer-generated holography, holographic data storage, interferometry recording of Bragg gratings as well as gratings of various types in semiconductor industry. Performance of mentioned techniques is essentially enhanced by providing a light beam with flat phase front and flat-top irradiance distribution. Therefore, transformation of Gaussian distribution of a TEM00 laser to flat-top (top hat, uniform) distribution is an important optical task. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality demanding holography and interferometry. As a solution it is suggested to apply refractive field mapping beam shaping optics πShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. High optical quality of resulting flat-top beam allows applying additional optical components to build various imaging optical systems for variation of beam size and shape to fulfil requirements of a particular application. This paper will describe design basics of refractive beam shapers and optical layouts of their applying in holography and laser interference lithography. Examples of real implementations and experimental results will be presented as well.

  20. X-ray phase radiography and tomography with grating interferometry and the reverse projection technique

    International Nuclear Information System (INIS)

    Wang, Zhili; Gao, Kun; Ge, Xin; Wu, Zhao; Chen, Heng; Wang, Shenghao; Wu, Ziyu; Zhu, Peiping; Yuan, Qingxi; Huang, Wanxia; Zhang, Kai

    2013-01-01

    X-ray grating interferometry provides substantially increased contrast over conventional absorption-based imaging methods, and therefore new and complementary information. Compared with other phase-contrast imaging techniques, x-ray grating interferometry can overcome some of the problems that have impaired the applications of x-ray phase-contrast radiography and phase tomography. Recently, special attention has been paid to the development of quantitative phase retrieval methods, which is mandatory to perform x-ray phase tomography, to achieve material identification, to differentiate distinct tissues, etc. Typically, the phase-stepping approach has been utilized for phase retrieval in grating interferometry. This method requires a grating scanning and acquisition of multiple radiographic projections, and therefore is disadvantageous in terms of imaging speed and radiation damage. Here we present an innovative, highly sensitive approach, dubbed ‘reverse projection’ (RP), for quantitative phase retrieval. Compared with the phase-stepping approach, the present RP method abandons grating scanning completely, and thus is advantageous due to its much higher efficiency and the reduced radiation dose, without the degradation of reconstruction quality. This review presents a detailed explanation of the principle of the RP method. Both radiography and phase tomography experiments are performed to validate the RP method. We believe that this new technique will find widespread applications in biomedical imaging and in vivo studies. (paper)

  1. Comparing interferometry techniques for multi-degree of freedom test mass readout

    International Nuclear Information System (INIS)

    Isleif, Katharina-Sophie; Gerberding, Oliver; Mehmet, Moritz; Schwarze, Thomas S; Heinzel, Gerhard; Danzmann, Karsten

    2016-01-01

    Laser interferometric readout systems with 1pm/Hz precision over long time scales have successfully been developed for LISA and LISA Pathfinder. Future gravitational physics experiments, for example in the fields of gravitational wave detection and geodesy, will potentially require similar levels of displacement and tilt readouts of multiple test masses in multiple degrees of freedom. In this article we compare currently available classic interferometry schemes with new techniques using phase modulations and complex readout algorithms. Based on a simple example we show that the new techniques have great potential to simplify interferometric readouts. (paper)

  2. REAL TIME MICRODISPLACEMENTS TESTING BY OPTO-DIGITAL HOLOGRAPHIC INTERFEROMETRY TECHNIQUE

    Directory of Open Access Journals (Sweden)

    L BOUAMAMA

    2007-12-01

    Since all the process is controlled numerically, it is possible to follow in real time using the holographic interferometry techniques, double exposure, real time or time average, any changes in the object under study and to start and stop the process at any time by adequate software. This can be done by subtracting a reference image by suitable software directly on the CCD camera. We show also, the ability of the technique to study in real time all evolutional phenomena.

  3. Physically-Based Interactive Flow Visualization Based on Schlieren and Interferometry Experimental Techniques

    KAUST Repository

    Brownlee, C.

    2011-11-01

    Understanding fluid flow is a difficult problem and of increasing importance as computational fluid dynamics (CFD) produces an abundance of simulation data. Experimental flow analysis has employed techniques such as shadowgraph, interferometry, and schlieren imaging for centuries, which allow empirical observation of inhomogeneous flows. Shadowgraphs provide an intuitive way of looking at small changes in flow dynamics through caustic effects while schlieren cutoffs introduce an intensity gradation for observing large scale directional changes in the flow. Interferometry tracks changes in phase-shift resulting in bands appearing. The combination of these shading effects provides an informative global analysis of overall fluid flow. Computational solutions for these methods have proven too complex until recently due to the fundamental physical interaction of light refracting through the flow field. In this paper, we introduce a novel method to simulate the refraction of light to generate synthetic shadowgraph, schlieren and interferometry images of time-varying scalar fields derived from computational fluid dynamics data. Our method computes physically accurate schlieren and shadowgraph images at interactive rates by utilizing a combination of GPGPU programming, acceleration methods, and data-dependent probabilistic schlieren cutoffs. Applications of our method to multifield data and custom application-dependent color filter creation are explored. Results comparing this method to previous schlieren approximations are finally presented. © 2011 IEEE.

  4. Frequency-Shifted Interferometry — A Versatile Fiber-Optic Sensing Technique

    Directory of Open Access Journals (Sweden)

    Fei Ye

    2014-06-01

    Full Text Available Fiber-optic sensing is a field that is developing at a fast pace. Novel fiber-optic sensor designs and sensing principles constantly open doors for new opportunities. In this paper, we review a fiber-optic sensing technique developed in our research group called frequency-shifted interferometry (FSI. This technique uses a continuous-wave light source, an optical frequency shifter, and a slow detector. We discuss the operation principles of several FSI implementations and show their applications in fiber length and dispersion measurement, locating weak reflections along a fiber link, fiber-optic sensor multiplexing, and high-sensitivity cavity ring-down measurement. Detailed analysis of FSI system parameters is also presented.

  5. Acoustic measuring techniques for suspended sediment

    Science.gov (United States)

    Gruber, P.; Felix, D.; Storti, G.; Lattuada, M.; Fleckenstein, P.; Deschwanden, F.

    2016-11-01

    Acoustic signals can be used in various ways for suspended sediment monitoring. One possibility which lends itself particularly well in the context of hydropower plants (HPPs), is to use installations for acoustic discharge measurement (ADM). Such installations already exist at waterways of many HPPs. Similar to certain turbidimeters, the attenuation of the forward scattered signal travelling through the water-sediment mixture is correlated with suspended sediment concentration (SSC). This correlation can be based on reference SSCs, e.g. from gravimetric analyses of bottle samples. Without the need of additional sensors and practically maintenance-free, this method is used successfully in the HPP Fieschertal to warn the HPP operator of high SSC to prevent excessive turbine abrasion. Acoustic methods and systems that allow for estimating both SSC and particle size distribution (PSD) are under development. The simultaneous determination of SSC and PSD is not possible using a single frequency. Therefore, multi-frequency approaches are investigated for generally scattered signals. When backscattered signals are used, a stronger frequency dependency can be exploited. However, the reliable simultaneous determination of particle size (and distribution) and concentration is still a major challenge due to a low signal-to-noise ratio and an ill- posed problem of estimating concentration and size from recorded signals. The optimal setup configuration (angles, frequencies) for such a system is not unique and further investigations are recommended.

  6. Applicability of coda wave interferometry technique for measurement of acoustoelastic effect of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Sung Woo [Dept. of Safety Engineering, Pukyong National University, Busan (Korea, Republic of)

    2016-12-15

    In this study, we examined the applicability of coda wave interferometry (CWI) technique, which was developed to characterize seismic waves, to detect and evaluate change in the velocity of ultrasonic waves in concrete due to acoustoelastic effect. Ultrasonic wave measurements and compressive loading tests were conducted on a concrete specimen. The measured wave signals were processed with CWI to detect and evaluate the relative velocity change with respect to the stress state of the specimen. A phase change due to the acoustoelastic effect of concrete was clearly detected in the late-arriving coda wave. This shows that the relative velocity change of ultrasonic waves in concrete due to the acoustoelastic effect can be evaluated successfully and precisely using CWI.

  7. Applicability of coda wave interferometry technique for measurement of acoustoelastic effect of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Sung Woo [Dept. of of Safety Engineering, Pukyong National University, Busan (Korea, Republic of)

    2014-12-15

    In this study, we examined the applicability of coda wave interferometry (CWI) technique, which was developed to characterize seismic waves, to detect and evaluate change in the velocity of ultrasonic waves in concrete due to acoustoelastic effect. Ultrasonic wave measurements and compressive loading tests were conducted on a concrete specimen. The measured wave signals were processed with CWI to detect and evaluate the relative velocity change with respect to the stress state of the specimen. A phase change due to the acoustoelastic effect of concrete was clearly detected in the late-arriving coda wave. This shows that the relative velocity change of ultrasonic waves in concrete due to the acoustoelastic effect can be evaluated successfully and precisely using CWI.

  8. Laser Techniques on Acoustically Levitated Droplets

    Directory of Open Access Journals (Sweden)

    Cannuli Antonio

    2018-01-01

    acoustically levitated droplets of trehalose aqueous solutions in order to perform spectroscopic analyses as a function of concentration and to test the theoretical diameter law. The study of such systems is important in order to better understand the behaviour of trehalose-synthesizing extremophiles that live in extreme environments. In particular, it will be shown how acoustic levitation, combined with optical spectroscopic instruments allows to explore a wide concentration range and to test the validity of the diameter law as a function of levitation lag time, i.e. the D2 vs t law. On this purpose a direct diameter monitoring by a video camera and a laser pointer was first performed; then the diameter was also evaluated by an indirect measure through an OH/CH band area ratio analysis of collected Raman and Infrared spectra. It clearly emerges that D2 vs t follows a linear trend for about 20 minutes, reaching then a plateau at longer time. This result shows how trehalose is able to avoid total water evaporation, this property being essential for the surviving of organisms under extreme environmental conditions.

  9. Development of a measurement technique to characterize erosion and redeposition in a tokamak by speckle interferometry

    International Nuclear Information System (INIS)

    Dore, P.

    2006-11-01

    This work aims at proving the feasibility of temporal phase shifting speckle interferometry to make erosion/redeposition measurements on plasma facing components in situ on a tokamak. Results show clearly that the interferometric technique can be implemented on a tokamak to provide erosion/redeposition measurements. The optical setup and the interferograms acquisition and processing have been developed and tested in laboratory before being suited to the complex tokamak environment. We finally have an optical technique able to characterize erosion/redeposition mechanisms (amount of eroded/redeposited material, location) on optically rough plasma facing components (carbon fibre composite, tungsten). These components, suffering from random displacements (as vibrations) during acquisition, are relatively large (∼ 50 x 50 cm 2 ) and could be situated far away from the CCD camera (∼ 3 m). Now, we need to define the regions of plasma facing components where we want to make erosion and redeposition measurements. After that, we propose a diagnostic to validate the optical technique in situ on a tokamak, allowing us to develop a diagnostic for ITER. (author)

  10. Application of interferometry and Faraday rotation techniques for density measurements on ITER

    International Nuclear Information System (INIS)

    Snider, R.T.; Carlstrom, T.N.; Ma, C.H.; Peebles, W.A.

    1995-01-01

    There is a need for real time, reliable density measurement for density control, compatible with the restricted access and radiation environment on ITER. Line average density measurements using microwave or laser interferometry techniques have proven to be robust and reliable for density control on contemporary tokamaks. In ITER, the large path length, high density and density gradients, limit the wavelength of a probing beam to shorter then about 50 microm due to refraction effects. In this paper the authors consider the design of short wavelength vibration compensated interferometers and Faraday rotation techniques for density measurements on ITER. These techniques allow operation of the diagnostics without a prohibitively large vibration isolated structure and permits the optics to be mounted directly on the radial port plugs on ITER. A beam path designed for 10.6 microm (CO2 laser) with a tangential path through the plasma allows both an interferometer and a Faraday rotation measurement of the line average density with good density resolution while avoiding refraction problems. Plasma effects on the probing beams and design tradeoffs will be discussed along with radiation and long pulse issues. A proposed layout of the diagnostic for ITER will be present

  11. Acoustic monitoring techniques for corrosion degradation in cemented waste canisters

    International Nuclear Information System (INIS)

    Naish, C.C.; Buttle, D.; Wallace-Sims, R.; O'Brien, T.M.

    1991-01-01

    This report describes work to investigate acoustic emission as a non-intrusive monitor of corrosion and degradation of cemented wasteforms where the waste is a potentially reactive metal. The acoustic data collected shows good correlation with the corrosion rate as measured by hydrogen gas evolution rates and the electrochemically measured corrosion rates post cement hardening. The technique has been shown to be sensitive in detecting stress caused by expansive corrosion product within the cemented wasteform. The attenuation of the acoustic signal by the wasteform reduced the signal received by the monitoring equipment by a factor of 10 over a distance of approximately 150-400 mm, dependent on the water level in the cement. Full size packages were successfully monitored. It is concluded that the technique offers good potential for monitoring cemented containers of the more reactive metals, for example Magnox and aluminium. (author)

  12. Characterization of Nb SRF cavity materials by white light interferometry and replica techniques

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chen [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); The Applied Science Department, The College of William and Mary, Williamsburg, VA 23185 (United States); Reece, Charles [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Kelley, Michael, E-mail: mkelley@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); The Applied Science Department, The College of William and Mary, Williamsburg, VA 23185 (United States)

    2013-06-01

    Much work has shown that the topography of the interior surface is an important contributor to the performance of Nb superconducting radiofrequency (SRF) accelerator cavities. Micron-scale topography is implicated in non-linear loss mechanisms that limit the useful accelerating gradient range and impact cryogenic cost. Aggressive final chemical treatments in cavity production seek to reliably obtain “smoothest” surfaces with superior performance. Process development suffers because the cavity interior surface cannot be viewed directly without cutting out pieces, rendering the cavities unavailable for further study. Here we explore replica techniques as an alternative, providing imprints of cavity internal surface that can be readily examined. A second matter is the topography measurement technique used. Atomic force microscopy (AFM) has proven successful, but too time intensive for routine use in this application. We therefore introduce white light interferometry (WLI) as an alternative approach. We examined real surfaces and their replicas, using AFM and WLI. We find that the replica/WLI is promising to provide the large majority of the desired information, recognizing that a trade-off is being made between best lateral resolution (AFM) and the opportunity to examine much more surface area (WLI).

  13. Uncertainty Analysis for Oil-Film Interferometry Skin-Friction Measurement Techniques

    Science.gov (United States)

    Naughton, Jonathan W.; Brown, James L.; Merriam, Marshal (Technical Monitor)

    1996-01-01

    Over the past 20 years, the use of oil-film interferometry to measure the skin friction coefficient (C(sub f) = tau/q where tau is the surface shear stress and q is the dynamic pressure) has increased. Different forms of this oil-film technique with various levels of accuracy and ease of use have been successfully applied in a wide range of flows. The method's popularity is growing due to its relative ease of implementation and minimal intrusiveness as well as an increased demand for C(sub f) measurements. Nonetheless, the accuracy of these methods has not been rigorously addressed to date. Most researchers have simply shown that the skin-friction measurements made using these techniques compare favorably with other measurements and theory, most of which are only accurate to within 5-20%. The use of skin-friction data in the design of commercial aircraft, whose drag at cruise is 50% skin-friction drag, and in the validation of computational fluid dynamics programs warrants better uncertainty estimates. Additional information is contained in the original extended abstract.

  14. Monitoring power breakers using vibro acoustic techniques

    Directory of Open Access Journals (Sweden)

    Horia Balan

    2017-09-01

    Full Text Available Speaking about the commutation’s equipment, it can be said that the best solution in increasing reliability and lowering the maintenance costs is a continuous monitoring of the equipment. However, if the price/quality ratio is considered, it is obvious that, for the moment, the diagnosis can be also an acceptable solution. Nowadays the predictive maintenance for equipment’s diagnosis is currently replacing the preventive diagnosis. An efficient modality of lowering the maintenance costs is to online monitoring the power breakers, during their operation in the power systems. Consequently any connecting/disconnecting operations may be used in diagnosing a power breaker. Thus any supplementary and superfluous tests and/or maintenance maneuvers are avoided. The paper presents the operational maintenance in a power station with three high voltage active breakers, Areva type. The method of establishing the state of a breaker consists in the comparison between the signature of the acoustic signal provided by the manufacturer and the signal issued from the testing operation of the breaker’s state. The software processing procedure and the methodology of determining the faults of the monitored equipment are also developed. All the tests on the circuit breaker are made according the prescriptions of normative.

  15. Vehicle recognition by using acoustic signature and classic DSP techniques

    Directory of Open Access Journals (Sweden)

    María Fernanda Díaz Velásquez

    2016-06-01

    Full Text Available This paper shows the application of the classic technique of digital signal processing (DSP, the cross-correlation, used for the detection of acoustic signatures of road traffic in Cali city, Colombia. Future goal is to build a detection software that through real time measures allows us estimate the levels of acoustic pollution in the city by using simulation models of road traffic, in the framework of environmentally-friendly smart cities. Final results of the experimental tests showed an accuracy of 71.43% for specific vehicle detection.

  16. Characterizing the estuarine riverbed using acoustic technique

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Menezes, A.A.A.; Muthukumar, K.; Fernandes, W.A.; Saran, A.K.; Mehra, P.

    carried out using geostatistics and non- linear techniques. These methods have been applied to bathymetry and backscatter data collected using multi-beam echo sounder (EM 1002, M/s Kongsberg) operating at a frequency of 95 kHz, installed onboard..., May 04 & May 16 of 2007 respectively. The EM1002 multi-beam echo-sounding system possesses 111 preformed beams i.e., recording 111 depth values in a single ping. In addition to the depth, the system also records quantitative backscatter data...

  17. Forest parameter estimation using polarimetric SAR interferometry techniques at low frequencies

    International Nuclear Information System (INIS)

    Lee, Seung-Kuk

    2013-01-01

    Polarimetric Synthetic Aperture Radar Interferometry (Pol-InSAR) is an active radar remote sensing technique based on the coherent combination of both polarimetric and interferometric observables. The Pol-InSAR technique provided a step forward in quantitative forest parameter estimation. In the last decade, airborne SAR experiments evaluated the potential of Pol-InSAR techniques to estimate forest parameters (e.g., the forest height and biomass) with high accuracy over various local forest test sites. This dissertation addresses the actual status, potentials and limitations of Pol-InSAR inversion techniques for 3-D forest parameter estimations on a global scale using lower frequencies such as L- and P-band. The multi-baseline Pol-InSAR inversion technique is applied to optimize the performance with respect to the actual level of the vertical wave number and to mitigate the impact of temporal decorrelation on the Pol-InSAR forest parameter inversion. Temporal decorrelation is a critical issue for successful Pol-InSAR inversion in the case of repeat-pass Pol-InSAR data, as provided by conventional satellites or airborne SAR systems. Despite the limiting impact of temporal decorrelation in Pol-InSAR inversion, it remains a poorly understood factor in forest height inversion. Therefore, the main goal of this dissertation is to provide a quantitative estimation of the temporal decorrelation effects by using multi-baseline Pol-InSAR data. A new approach to quantify the different temporal decorrelation components is proposed and discussed. Temporal decorrelation coefficients are estimated for temporal baselines ranging from 10 minutes to 54 days and are converted to height inversion errors. In addition, the potential of Pol-InSAR forest parameter estimation techniques is addressed and projected onto future spaceborne system configurations and mission scenarios (Tandem-L and BIOMASS satellite missions at L- and P-band). The impact of the system parameters (e.g., bandwidth

  18. Acoustic, finite-difference, time-domain technique development

    International Nuclear Information System (INIS)

    Kunz, K.

    1994-01-01

    A close analog exists between the behavior of sound waves in an ideal gas and the radiated waves of electromagnetics. This analog has been exploited to obtain an acoustic, finite-difference, time-domain (AFDTD) technique capable of treating small signal vibrations in elastic media, such as air, water, and metal, with the important feature of bending motion included in the behavior of the metal. This bending motion is particularly important when the metal is formed into sheets or plates. Bending motion does not have an analog in electromagnetics, but can be readily appended to the acoustic treatment since it appears as a single additional term in the force equation for plate motion, which is otherwise analogous to the electromagnetic wave equation. The AFDTD technique has been implemented in a code architecture that duplicates the electromagnetic, finite-difference, time-domain technique code. The main difference in the implementation is the form of the first-order coupled differential equations obtained from the wave equation. The gradient of pressure and divergence of velocity appear in these equations in the place of curls of the electric and magnetic fields. Other small changes exist as well, but the codes are essentially interchangeable. The pre- and post-processing for model construction and response-data evaluation of the electromagnetic code, in the form of the TSAR code at Lawrence Livermore National Laboratory, can be used for the acoustic version. A variety of applications is possible, pending validation of the bending phenomenon. The applications include acoustic-radiation-pattern predictions for a submerged object; mine detection analysis; structural noise analysis for cars; acoustic barrier analysis; and symphonic hall/auditorium predictions and speaker enclosure modeling

  19. Study of uranium dioxide pellets by micro-acoustic techniques

    International Nuclear Information System (INIS)

    Roque, V.

    1999-01-01

    In order to reduce the volume of spent fuel to reprocess and to improve the productivity and the safety of the nuclear reactor, 'Electricite De France' aim to increase the average fuel discharge burn-up. To elaborate the safety reports, EDF develops codes to simulate the thermo-mechanical behaviour of the nuclear fuel element. These numeric simulations need to evaluate accurately and locally the evolution of the material and of its properties. One of the major concern today is the local characterisation of the intrinsic volume fraction porosity and the mechanical properties of the irradiated fuel. The fuel pellet fragmentation, the steep radial gradient in its physical properties evolution and the chemical evolution of the irradiated material make difficult nay the use of the conventional techniques. This leads EDF to pay interest for the use of two complementary techniques: micro-indentation on the one hand and acoustic methods on the other hand (acoustic microscopy and micro-echography), with an additional constrain to perform on active materials. The objective of this work has been to adapt the acoustic methods for an application on uranium dioxide pellets, used as nuclear fuel in Water Pressurised Reactor. Acquisitions protocols have been set to measure accurately the Rayleigh velocity and the longitudinal velocity of the UO 2 . Using these protocols, we have calibrated these acoustic methods by analysing non irradiated nuclear pellet which properties were well known. This process enable to quantify the effects of different physico-chemical parameters of the UO 2 on the ultrasonic velocities measured. Particularly, the large influence of the porosity has been demonstrated and empirical laws to express the evolution of the acoustic velocities as a function of the volume fraction porosity were established. Moreover, we have established a methodology to characterise the intrinsic elastic constants and the volume fraction porosity on irradiated UO 2 fuel pellets

  20. Digital holographic interferometry: A novel optical calorimetry technique for radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Cavan, Alicia, E-mail: alicia.cavan@cdhb.health.nz [Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand and Christchurch Hospital, Private Bag 4710, Christchurch 8140 (New Zealand); Meyer, Juergen, E-mail: juergen@uw.edu [Department of Radiation Oncology, University of Washington, 1959 Northeast Pacific Street, Box 356043, Seattle, Washington 98195 (United States)

    2014-02-15

    Purpose: To develop and demonstrate the proof-of-principle of a novel optical calorimetry method to determine radiation absorbed dose in a transparent medium. Methods: The calorimetric property of water is measured during irradiation by means of an interferometer, which detects temperature-induced changes in the refractive index that can be mathematically related to absorbed dose. The proposed method uses a technique called digital holographic interferometry (DHI), which comprises an optical laser interferometer setup and consecutive physical reconstruction of the recorded wave fronts by means of the Fresnel transform. This paper describes the conceptual framework and provides the mathematical basis for DHI dosimetry. Dose distributions from a high dose rate Brachytherapy source were measured by a prototype optical setup to demonstrate the feasibility of the approach. Results: The developed DHI dosimeter successfully determined absorbed dose distributions in water in the region adjacent to a high dose rate Brachytherapy source. A temperature change of 0.0381 K across a distance of 6.8 mm near the source was measured, corresponding to a dose of 159.3 Gy. The standard deviation in a typical measurement set was ±3.45 Gy (corresponding to an uncertainty in the temperature value of ±8.3 × 10{sup −4} K). The relative dose fall off was in agreement with treatment planning system modeled data. Conclusions: First results with a prototype optical setup and a Brachytherapy source demonstrate the proof-of-principle of the approach. The prototype achieves high spatial resolution of approximately 3 × 10{sup −5} m. The general approach is fundamentally independent of the radiation type and energy. The sensitivity range determined indicates that the method is predominantly suitable for high dose rate applications. Further work is required to determine absolute dose in all three dimensions.

  1. Interferometry with polarised neutrons

    International Nuclear Information System (INIS)

    Badurek, G.

    1978-01-01

    This paper aimed to give an outline of what might be expected from an extension of polarized beam techniques in neutron interferometry and how it could be achieved properly and what is the present state of this special field of interferometry

  2. Atomic interferometry

    International Nuclear Information System (INIS)

    Baudon, J.; Robert, J.

    2004-01-01

    Since the theoretical works of L. De Broglie (1924) and the famous experiment of Davisson and Germer (1927), we know that a wave is linked with any particle of mass m by the relation λ = h/(mv), where λ is the wavelength, v the particle velocity and h is the Planck constant. The basic principle of the interferometry of any material particle, atom, molecule or aggregate is simple: using a simple incident wave, several mutually consistent waves (with well-defined relative phases) are generated and controllable phase-shifts are introduced between them in order to generate a wave which is the sum of the previous waves. An interference figure is obtained which consists in a succession of dark and bright fringes. The atomic interferometry is based on the same principle but involves different techniques, different wave equations, but also different beams, sources and correlations which are described in this book. Because of the small possible wavelengths and the wide range of possible atomic interactions, atomic interferometers can be used in many domains from the sub-micron lithography to the construction of sensors like: inertial sensors, gravity-meters, accelerometers, gyro-meters etc. The first chapter is a preliminary study of the space and time diffraction of atoms. The next chapters is devoted to the description of slit, light separation and polarization interferometers, and the last chapter treats of the properties of Bose-Einstein condensates which are interesting in atomic interferometry. (J.S.)

  3. Characterization of irradiation damage distribution near TiO2/SrTiO3 interfaces using coherent acoustic phonon interferometry

    International Nuclear Information System (INIS)

    Yarotski, Dmitry; Yan Li; Jia Quanxi; Taylor, Antoinette J.; Fu Engang; Wang Yongqiang; Uberuaga, Blas P.

    2012-01-01

    We apply ultrafast coherent acoustic phonon interferometry to characterize the distribution of the radiation damage near the TiO 2 /SrTiO 3 interfaces. We show that the optical and mechanical properties of anatase TiO 2 remain unaffected by the radiation dosages in the 0.1÷5 dpa (displacements per atom) range, while the degraded optical response indicates a significant defect accumulation in the interfacial region of SrTiO 3 at 0.1 dpa and subsequent amorphization at 3 dpa. Comparison between the theoretical simulations and the experimental results reveals an almost threefold reduction of the sound velocity in the irradiated SrTiO 3 layer with peak damage levels of 3 and 5 dpa.

  4. A three-microphone acoustic reflection technique using transmitted acoustic waves in the airway.

    Science.gov (United States)

    Fujimoto, Yuki; Huang, Jyongsu; Fukunaga, Toshiharu; Kato, Ryo; Higashino, Mari; Shinomiya, Shohei; Kitadate, Shoko; Takahara, Yutaka; Yamaya, Atsuyo; Saito, Masatoshi; Kobayashi, Makoto; Kojima, Koji; Oikawa, Taku; Nakagawa, Ken; Tsuchihara, Katsuma; Iguchi, Masaharu; Takahashi, Masakatsu; Mizuno, Shiro; Osanai, Kazuhiro; Toga, Hirohisa

    2013-10-15

    The acoustic reflection technique noninvasively measures airway cross-sectional area vs. distance functions and uses a wave tube with a constant cross-sectional area to separate incidental and reflected waves introduced into the mouth or nostril. The accuracy of estimated cross-sectional areas gets worse in the deeper distances due to the nature of marching algorithms, i.e., errors of the estimated areas in the closer distances accumulate to those in the further distances. Here we present a new technique of acoustic reflection from measuring transmitted acoustic waves in the airway with three microphones and without employing a wave tube. Using miniaturized microphones mounted on a catheter, we estimated reflection coefficients among the microphones and separated incidental and reflected waves. A model study showed that the estimated cross-sectional area vs. distance function was coincident with the conventional two-microphone method, and it did not change with altered cross-sectional areas at the microphone position, although the estimated cross-sectional areas are relative values to that at the microphone position. The pharyngeal cross-sectional areas including retropalatal and retroglossal regions and the closing site during sleep was visualized in patients with obstructive sleep apnea. The method can be applicable to larger or smaller bronchi to evaluate the airspace and function in these localized airways.

  5. Speckle interferometry

    Science.gov (United States)

    Sirohi, Rajpal S.

    2002-03-01

    Illumination of a rough surface by a coherent monochromatic wave creates a grainy structure in space termed a speckle pattern. It was considered a special kind of noise and was the bane of holographers. However, its information-carrying property was soon discovered and the phenomenon was used for metrological applications. The realization that a speckle pattern carried information led to a new measurement technique known as speckle interferometry (SI). Although the speckle phenomenon in itself is a consequence of interference among numerous randomly dephased waves, a reference wave is required in SI. Further, it employs an imaging geometry. Initially SI was performed mostly by using silver emulsions as the recording media. The double-exposure specklegram was filtered to extract the desired information. Since SI can be configured so as to be sensitive to the in-plane displacement component, the out-of-plane displacement component or their derivatives, the interferograms corresponding to these were extracted from the specklegram for further analysis. Since the speckle size can be controlled by the F number of the imaging lens, it was soon realized that SI could be performed with electronic detection, thereby increasing its accuracy and speed of measurement. Furthermore, a phase-shifting technique can also be incorporated. This technique came to be known as electronic speckle pattern interferometry (ESPI). It employed the same experimental configurations as SI. ESPI found many industrial applications as it supplements holographic interferometry. We present three examples covering diverse areas. In one application it has been used to measure residual stress in a blank recordable compact disk. In another application, microscopic ESPI has been used to study the influence of relative humidity on paint-coated figurines and also the effect of a conservation agent applied on top of this. The final application is to find the defects in pipes. These diverse applications

  6. Progress on acoustic techniques for LMFBR structural surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Burton, E J; Bentley, P G; McKnight, J A [RNL, UKAEA, Risley, Warrington, Cheshire (United Kingdom)

    1980-11-01

    Acoustic techniques are being developed to monitor remotely the incipient events of various modes of failure. Topics have been selected from the development programme which are either of special importance or in which significant advances have been made recently. Ultrasonic inspection of stainless steel welds is difficult and one alternative approach which is being explored is to identify manufacturing defects during fabrication by monitoring the welding processes. Preliminary measurements are described of the acoustic events measured during deliberately defective welding tests in the laboratory and some initial analysis using pattern recognition techniques is described. The assessment of structural failures using probability analysis has emphasised the potential value of continuous monitoring during operation and this has led to the investigation into the use of vibrational analysis and acoustic emission as monitoring techniques. Mechanical failure from fatigue may be anticipated from measurement of vibrational modes and experience from PFR and from models have indicated the depth of detailed understanding required to achieve this. In the laboratory a vessel with an artificial defect has been pressurised to failure. Detection of the weak stress wave emissions was possible but difficult and the prospects for on-line monitoring are discussed. Ultrasonic technology for providing images of components immersed in the opaque sodium of LMFBRs is being developed. Images are cormed by the physical scanning of a target using transducers in a pulse-echo mode. Lead zirconate transducers have been developed which can be deployed during reactor shut-down. The first application will be to examine a limited area of the core of PFR. Handling the data from such an experiment involves developing methods for reading and storing the information from such ultrasonic echo. Such techniques have been tested in real time by simulation in a water model. Methods of enhancing the images to be

  7. Experimental investigation for determination of thermal effects in a Nd: YAG laser crystal by use of interferometry technique

    International Nuclear Information System (INIS)

    Safary, E.; Movahedinejad, H.; Razzaghi, H.; Haj Esmaeilbeigi, F.; Tohidi, T.; Shiri, M.

    2007-01-01

    Thermal effects have an important role in high power solid state laser designing. Known of this effect and their roles on intensity and quality of output beam needs so many experiments. In this paper, we focused on influence of temperature distribution on thermal lensing in the Nd:YAG laser by use of interferometry technique. Then we used from a plariscop set up for describing of intensity reduce and distortion of the wave shape when it use from the Polaroid into the resonator at side pump.

  8. Holographic interferometry - a nondestructive inspection technique for early detection of construction element damages

    International Nuclear Information System (INIS)

    Wachutka, H.; Fritzsch, W.; Gruenewald, K.

    1977-01-01

    After a short introduction into the fundamentals of holographic interferometry, the application of this process to non-destructive material testing is explained. Practical examples of qualitative and quantitative deformation measurements carried out on building elements of different materials as well as on metallic and nonmetallic combinations show the possibilities of early recognition of manufacturing flaws and weak points due to the construction and also the determination of construction material characteristic coefficients. (orig.) [de

  9. Detection techniques in low-coherence interferometry and their impact on overall measurement accuracy

    Czech Academy of Sciences Publication Activity Database

    Pikálek, Tomáš; Fořt, Tomáš; Buchta, Zdeněk

    2014-01-01

    Roč. 53, č. 36 (2014), s. 8463-8470 ISSN 1559-128X R&D Projects: GA ČR GB14-36681G; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : interferometry * fringe analysis * surface measurements, figure * optical data processing Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.784, year: 2014

  10. Detection of cavitation vortex in hydraulic turbines using acoustic techniques

    International Nuclear Information System (INIS)

    Candel, I; Ioana, C; Bunea, F; Politehnica University of Bucharest (Romania))" data-affiliation=" (Power Engineering Faculty, Politehnica University of Bucharest (Romania))" >Dunca, G; Politehnica University of Bucharest (Romania))" data-affiliation=" (Power Engineering Faculty, Politehnica University of Bucharest (Romania))" >Bucur, D M; Division Technique Générale, Grenoble (France))" data-affiliation=" (Electricité de France, Division Technique Générale, Grenoble (France))" >Reeb, B; Ciocan, G D

    2014-01-01

    Cavitation phenomena are known for their destructive capacity in hydraulic machineries and are caused by the pressure decrease followed by an implosion when the cavitation bubbles find an adverse pressure gradient. A helical vortex appears in the turbine diffuser cone at partial flow rate operation and can be cavitating in its core. Cavity volumes and vortex frequencies vary with the under-pressure level. If the vortex frequency comes close to one of the eigen frequencies of the turbine, a resonance phenomenon may occur, the unsteady fluctuations can be amplified and lead to important turbine and hydraulic circuit damage. Conventional cavitation vortex detection techniques are based on passive devices (pressure sensors or accelerometers). Limited sensor bandwidths and low frequency response limit the vortex detection and characterization information provided by the passive techniques. In order to go beyond these techniques and develop a new active one that will remove these drawbacks, previous work in the field has shown that techniques based on acoustic signals using adapted signal content to a particular hydraulic situation, can be more robust and accurate. The cavitation vortex effects in the water flow profile downstream hydraulic turbines runner are responsible for signal content modifications. Basic signal techniques use narrow band signals traveling inside the flow from an emitting transducer to a receiving one (active sensors). Emissions of wide band signals in the flow during the apparition and development of the vortex embeds changes in the received signals. Signal processing methods are used to estimate the cavitation apparition and evolution. Tests done in a reduced scale facility showed that due to the increasing flow rate, the signal -- vortex interaction is seen as modifications on the received signal's high order statistics and bandwidth. Wide band acoustic transducers have a higher dynamic range over mechanical elements; the system

  11. Speckle Interferometry

    Science.gov (United States)

    Chiang, F. P.; Jin, F.; Wang, Q.; Zhu, N.

    Before the milestone work of Leedertz in 1970 coherent speckles generated from a laser illuminated object are considered noise to be eliminated or minimized. Leedertz shows that coherent speckles are actually information carriers. Since then the speckle technique has found many applications to fields of mechanics, metrology, nondestructive evaluation and material sciences. Speckles need not be coherent. Artificially created socalled white light speckles can also be used as information carriers. In this paper we present two recent developments of speckle technique with applications to micromechanics problems using SIEM (Speckle Interferometry with Electron Microscopy), to nondestructive evaluation of crevice corrosion and composite disbond and vibration of large structures using TADS (Time-Average Digital Specklegraphy).

  12. Mechanical seal monitoring technique by acoustic emission measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, Tadashi; Fujita, Yoshihiro; Kawaguchi, Kazunori; Saito, Kazuhiro; Yokota, Setsuo; Hisada, Yasuhide; Masahiro, Komatsu

    1987-09-20

    This report describes a technique for mechanical seal monitoring through acoustic emission (AE) measurement. The equipment consists of an AE sensor, preamplifier, multiplexer, main amplifier, effective value transducer and computer system. When the sealed liquid pressure undergoes a large change, the seal surface configuration is monitored and evaluated accurately through AE measurement. If the mechanical seal surface id damaged or worn, the AE level is kept high or continues to fluctuate largely for a rather long period. When leak occurs, the AE value shows great fluctuations either at extremely low levels or at high levels. The former trend is considered to result from a decrease in solid contact due to an excessive amount of liquid film being formed at the seal surface during leak. In the latter case, the leak is attributed to severe damage to the seal surface. (18 figs, 1 tab, 5 photos, 3 refs)

  13. A Procedure to Map Subsidence at the Regional Scale Using the Persistent Scatterer Interferometry (PSI Technique

    Directory of Open Access Journals (Sweden)

    Ascanio Rosi

    2014-10-01

    Full Text Available In this paper, we present a procedure to map subsidence at the regional scale by means of persistent scatterer interferometry (PSI. Subsidence analysis is usually restricted to plain areas and where the presence of this phenomenon is already known. The proposed procedure allows a fast identification of subsidences in large and hilly-mountainous areas. The test area is the Tuscany region, in Central Italy, where several areas are affected by natural and anthropogenic subsidence and where PSI data acquired by the Envisat satellite are available both in ascending and descending orbit. The procedure consists of the definition of the vertical and horizontal components of the deformation measured by satellite at first, then of the calculation of the “real” displacement direction, so that mainly vertical deformations can be individuated and mapped.

  14. Failure Mechanism of Rock Bridge Based on Acoustic Emission Technique

    Directory of Open Access Journals (Sweden)

    Guoqing Chen

    2015-01-01

    Full Text Available Acoustic emission (AE technique is widely used in various fields as a reliable nondestructive examination technology. Two experimental tests were carried out in a rock mechanics laboratory, which include (1 small scale direct shear tests of rock bridge with different lengths and (2 large scale landslide model with locked section. The relationship of AE event count and record time was analyzed during the tests. The AE source location technology and comparative analysis with its actual failure model were done. It can be found that whether it is small scale test or large scale landslide model test, AE technique accurately located the AE source point, which reflected the failure generation and expansion of internal cracks in rock samples. Large scale landslide model with locked section test showed that rock bridge in rocky slope has typical brittle failure behavior. The two tests based on AE technique well revealed the rock failure mechanism in rocky slope and clarified the cause of high speed and long distance sliding of rocky slope.

  15. Radio Occultation Experiments with Venus Express and Mars Express using the Planetary Radio Interferometry and Doppler Experiment (PRIDE) Technique

    Science.gov (United States)

    Bocanegra Bahamon, T.; Gurvits, L.; Molera Calves, G.; Cimo, G.; Duev, D.; Pogrebenko, S.; Dirkx, D.; Rosenblatt, P.

    2017-12-01

    The Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a technique that can be used to enhance multiple radio science experiments of planetary missions. By 'eavesdropping' on the spacecraft signal using radio telescopes from different VLBI networks around the world, the PRIDE technique provides precise open-loop Doppler and VLBI observables to able to reconstruct the spacecraft's orbit. The application of this technique for atmospheric studies has been assessed by observing ESA's Venus Express (VEX) and Mars Express (MEX) during multiple Venus and Mars occultation events between 2012 and 2014. From these observing sessions density, temperature and pressure profiles of Venus and Mars neutral atmosphere and ionosphere have been retrieved. We present an error propagation analysis where the uncertainties of the atmospheric properties measured with this technique have been derived. These activities serve as demonstration of the applicability of the PRIDE technique for radio occultation studies, and provides a benchmark against the traditional Doppler tracking provided by the NASA's DSN and ESA's Estrack networks for these same purposes, in the framework of the upcoming ESA JUICE mission to the Jovian system.

  16. Damage detection in wind turbine blades using acoustic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Juengert, A., E-mail: anne.juengert@mpa.uni-stuttgart.de [Univ. of Stuttgart, Materialpruefungsanstalt Stuttgart, Stuttgart (Germany)

    2013-05-15

    Facing climate change, the use of renewable energy gains importance. The wind energy sector grows very fast. Bigger and more powerful wind turbines will be built in the coming decades and the safety and reliability of the turbines will become more important. Wind turbine blades have to be inspected at regular intervals, because they are highly stressed during operation and a blade breakdown can cause big economic damages. The turbine blades consist of fiber reinforced plastics (GFRP/CFRP) and sandwich areas containing wood or plastic foam. The blades are manufactured as two halves and glued together afterwards. Typical damages are delaminations within the GFRP or the sandwich and missing adhesive or deficient bond at the bonding surfaces. The regular inspections of wind turbine blades are performed manually by experts and are limited to visual appraisals and simple tapping tests. To improve the inspections of wind turbine blades non-destructive testing techniques using acoustic waves are being developed. To detect delaminations within the laminates of the turbine blade, a local resonance spectroscopy was used. To detect missing bond areas from the outside of the blade the impulse-echo-technique was applied. This paper is an updated reprint of an article published on ndt.net in 2008. (author)

  17. Damage detection in wind turbine blades using acoustic techniques

    International Nuclear Information System (INIS)

    Juengert, A.

    2013-01-01

    Facing climate change, the use of renewable energy gains importance. The wind energy sector grows very fast. Bigger and more powerful wind turbines will be built in the coming decades and the safety and reliability of the turbines will become more important. Wind turbine blades have to be inspected at regular intervals, because they are highly stressed during operation and a blade breakdown can cause big economic damages. The turbine blades consist of fiber reinforced plastics (GFRP/CFRP) and sandwich areas containing wood or plastic foam. The blades are manufactured as two halves and glued together afterwards. Typical damages are delaminations within the GFRP or the sandwich and missing adhesive or deficient bond at the bonding surfaces. The regular inspections of wind turbine blades are performed manually by experts and are limited to visual appraisals and simple tapping tests. To improve the inspections of wind turbine blades non-destructive testing techniques using acoustic waves are being developed. To detect delaminations within the laminates of the turbine blade, a local resonance spectroscopy was used. To detect missing bond areas from the outside of the blade the impulse-echo-technique was applied. This paper is an updated reprint of an article published on ndt.net in 2008. (author)

  18. Principles of Stellar Interferometry

    CERN Document Server

    Glindemann, Andreas

    2011-01-01

    Over the last decade, stellar interferometry has developed from a specialist tool to a mainstream observing technique, attracting scientists whose research benefits from milliarcsecond angular resolution. Stellar interferometry has become part of the astronomer’s toolbox, complementing single-telescope observations by providing unique capabilities that will advance astronomical research. This carefully written book is intended to provide a solid understanding of the principles of stellar interferometry to students starting an astronomical research project in this field or to develop instruments and to astronomers using interferometry but who are not interferometrists per se. Illustrated by excellent drawings and calculated graphs the imaging process in stellar interferometers is explained starting from first principles on light propagation and diffraction wave propagation through turbulence is described in detail using Kolmogorov statistics the impact of turbulence on the imaging process is discussed both f...

  19. Mapping Ground Subsidence Phenomena in Ho Chi Minh City through the Radar Interferometry Technique Using ALOS PALSAR Data

    Directory of Open Access Journals (Sweden)

    Dinh Ho Tong Minh

    2015-07-01

    Full Text Available The rapidly developing urbanization since the last decade of the 20th century has led to extensive groundwater extraction, resulting in subsidence in Ho Chi Minh City, Vietnam. Recent advances in multi-temporal spaceborne SAR interferometry, especially with a persistent scatters interferometry (PSI approach, has made this a robust remote sensing technique for measuring large-scale ground subsidence with millimetric accuracy. This work has presented an advanced PSI analysis, to provide an unprecedented spatial extent and continuous temporal coverage of the subsidence in Ho Chi Minh City from 2006 to 2010. The study shows that subsidence is most severe in the Holocene silt loam areas along the Sai Gon River and in the southwest of the city. The groundwater extraction resulting from urbanization and urban growth is mainly responsible for the subsidence. Subsidence in turn leads to more flooding and water nuisance. The correlation between the reference leveling velocity and the estimated PSI result is R2 = 0.88, and the root mean square error is 4.3 (mm/year, confirming their good agreement. From 2006 to 2010, the estimation of the average subsidence rate is -8.0 mm/year, with the maximum value up to -70 mm/year. After four years, in regions along Sai Gon River and in the southwest of the city, the land has sunk up to -12 cm. If not addressed, subsidence leads to the increase of inundation, both in frequency and spatial extent. Finally, regarding climate change, the effects of subsidence should be considered as appreciably greater than those resulting from rising sea level. It is essential to consider these two factors, because the city is inhabited by more than 7.5 million people, where subsidence directly impacts urban structures and infrastructure.

  20. Non-invasive acoustic-based monitoring of uranium in solution and H/D ratio

    Energy Technology Data Exchange (ETDEWEB)

    Pantea, Cristian [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Beedle, Christopher Craig [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sinha, Dipen N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lakis, Rollin Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-01

    The primary objective of this project is to adapt existing non-invasive acoustic techniques (Swept-Frequency Acoustic Interferometry and Gaussian-pulse acoustic technique) for the purpose of demonstrating the ability to quantify U or H/D ratios in solution. Furthermore, a successful demonstration will provide an easily implemented, low cost, and non-invasive method for remote and unattended uranium mass measurements for International Atomic Energy Agency (IAEA).

  1. Acoustic monitoring techniques for corrosion degradation in cemented waste canisters

    International Nuclear Information System (INIS)

    Naish, C.C.; Buttle, D.; Wallace-Sims, R.; O'Brien, T.M.

    1991-01-01

    This report describes work carried out to investigate acoustic emission as a monitor of corrosion and degradation of wasteforms where the waste is potentially reactive metal. Electronic monitoring equipment has been designed, built and tested to allow long-term monitoring of a number of waste packages simultaneously. Acoustic monitoring experiments were made on a range of 1 litre cemented Magnox and aluminium samples cast into canisters comparing the acoustic events with hydrogen gas evolution rates and electrochemical corrosion rates. The attenuation of the acoustic signals by the cement grout under a range of conditions has been studied to determine the volume of wasteform that can be satisfactorily monitored by one transducer. The final phase of the programme monitored the acoustic events from full size (200 litre) cemented, inactive, simulated aluminium swarf wastepackages prepared at the AEA waste cementation plant at Winfrith. (Author)

  2. Probe beam deflection technique as acoustic emission directionality sensor with photoacoustic emission source.

    Science.gov (United States)

    Barnes, Ronald A; Maswadi, Saher; Glickman, Randolph; Shadaram, Mehdi

    2014-01-20

    The goal of this paper is to demonstrate the unique capability of measuring the vector or angular information of propagating acoustic waves using an optical sensor. Acoustic waves were generated using photoacoustic interaction and detected by the probe beam deflection technique. Experiments and simulations were performed to study the interaction of acoustic emissions with an optical sensor in a coupling medium. The simulated results predict the probe beam and wavefront interaction and produced simulated signals that are verified by experiment.

  3. Acoustic Emission Technique Applied in Textiles Mechanical Characterization

    Directory of Open Access Journals (Sweden)

    Rios-Soberanis Carlos Rolando

    2017-01-01

    Full Text Available The common textile architecture/geometry are woven, braided, knitted, stitch boded, and Z-pinned. Fibres in textile form exhibit good out-of-plane properties and good fatigue and impact resistance, additionally, they have better dimensional stability and conformability. Besides the nature of the textile, the architecture has a great role in the mechanical behaviour and mechanisms of damage in textiles, therefore damage mechanisms and mechanical performance in structural applications textiles have been a major concern. Mechanical damage occurs to a large extent during the service lifetime consequently it is vital to understand the material mechanical behaviour by identifying its mechanisms of failure such as onset of damage, crack generation and propagation. In this work, textiles of different architecture were used to manufacture epoxy based composites in order to study failure events under tensile load by using acoustic emission technique which is a powerful characterization tool due to its link between AE data and fracture mechanics, which makes this relation a very useful from the engineering point of view.

  4. Developement of leakage localization technique by using acoustic signal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y. H.; Jeon, J. H.; Seo, D. H.; Kim, K. W. [KAIST, Daejeon (Korea, Republic of)

    2010-07-15

    The objective of this research is to develop a leakage monitoring system for pipelines or valves in the secondary water system of a nuclear power plant. The system aims to detect the existence of leakage and to estimate the leak location, especially by utilizing the noise generated from the leak. It is safe, precise real-time alert system compared with the previous monitoring methods and tools such as the visual test and the thermal imaging camera. When there exists leakage in the pipeline or valves of nuclear power plant, the noise due to gas flow is radiated through leak region. That is, the secondary water system with leakage generates different noise from the system without leakage. This motivates us to measure and analyze the noise generated from the secondary water system, so as firstly to detect the existence of leakage, and secondly to estimate the leak location by using the noise source identification technique such as beamforming and acoustic holography. Especially the beamforming method models the signal from the noise source to estimate the location of source. Therefore, it is necessary to model the noise due to leakage which is dependent upon parameters. In the process of leak localization, the reflected wave due to interior walls and the measurement noise should be removed for the precise estimation. Therefore, we attempt to characterize the reflected wave and the measurement noise by modeling the interior sound field, thus to remove them and to localize the leak location with high precision

  5. Kaon interferometry

    International Nuclear Information System (INIS)

    Roldao, C.G.; Padula, S.S.

    1994-01-01

    Preliminary results of the χ 2 analysis where data on kaon interferometry, obtained from the E859 Collaboration of the AGS/Brookhaven Nat.Lab., are compared with results of a hadronic resonance production model are presented. The main goal is to test the resolution power of the method here discussed when applied to the two-dimensional kaon interferometry

  6. Antihydrogen Experiment Gravity Interferometry Spectroscopy

    CERN Multimedia

    Trezzi, D; Dassa, L; Rienacker, B; Khalidova, O; Ferrari, G; Krasnicky, D; Perini, D; Cerchiari, G; Belov, A; Boscolo, I; Sacerdoti, M G; Ferragut, R O; Nedelec, P; Hinterberger, A; Al-qaradawi, I; Malbrunot, C L S; Brusa, R S; Prelz, F; Manuzio, G; Riccardi, C; Fontana, A; Genova, P; Haider, S; Haug, F; Turbabin, A; Castelli, F; Testera, G; Lagomarsino, V E; Doser, M; Penasa, L; Gninenko, S; Cataneo, F; Zenoni, A; Cabaret, L; Comparat, D P; Zmeskal, J; Scampoli, P; Nesteruk, K P; Dudarev, A; Kellerbauer, A G; Mariazzi, S; Carraro, C; Zavatarelli, S M

    The AEGIS experiment (Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy) has the aim of carrying out the first measurement of the gravitational interaction of antimatter to a precision of 1%, by applying techniques from atomic physics, laser spectroscopy and interferometry to a beam of antihydrogen atoms. A further goal of the experiment is to carry out spectroscopy of the antihydrogen atoms in flight.

  7. Studies on acoustic modelling techniques for CANDU reactors

    Energy Technology Data Exchange (ETDEWEB)

    Chatoorgoon, V; Zhou, R [Atomic Energy of Canada Ltd., Chalk River, ON (Canada)

    1996-12-31

    This paper reviews the current technology being used to predict acoustic resonance in fluid-filled piping systems. The paper also reports on the analysis of a simple benchmark experiment that yielded some valuable insights and understanding into acoustic damping. A volumetric drag formula for the ABAQUS code is presented. Its application in experiments has yielded better results than previously obtained using a constant volumetric drag. (author). 24 refs., 1 tab., 12 figs.

  8. Studies on acoustic modelling techniques for CANDU reactors

    International Nuclear Information System (INIS)

    Chatoorgoon, V.; Zhou, R.

    1995-01-01

    This paper reviews the current technology being used to predict acoustic resonance in fluid-filled piping systems. The paper also reports on the analysis of a simple benchmark experiment that yielded some valuable insights and understanding into acoustic damping. A volumetric drag formula for the ABAQUS code is presented. Its application in experiments has yielded better results than previously obtained using a constant volumetric drag. (author). 24 refs., 1 tab., 12 figs

  9. Ambiguity of source location in acoustic emission technique

    International Nuclear Information System (INIS)

    Barat, P.; Mukherjee, P.; Kalyanasundaram, P.; Raj, B.

    1996-01-01

    Location of acoustic emission (AE) source in a plane is detected from the difference of the arrival times of the AE signal to at least three sensors placed on it. The detected location may not be unique in all cases. In this paper, the condition for the unambiguous solution for the location of the source has been deduced mathematically in terms of arrival times of the AE signal, the coordinate of the three sensors and the acoustic velocity. (author)

  10. Review of Micro/Nano Nondestructive Evaluation Technique (II): Measurement of Acoustic Properties

    International Nuclear Information System (INIS)

    Kim, Chung Seok; Park, Ik Keun

    2012-01-01

    The present paper reviews the micro and nano nondestructive evaluation(NDE) technique that is possible to investigate the surface and measure the acoustic properties. The technical theory, features and applications of the ultrasonic atomic force microscopy(UAFM) and scanning acoustic microscopy(SAM) are illustrated. Especially, these technologies are possible to evaluate the mechanical properties in micro/nano structure and surface through the measurement of acoustic properties in addition to the observation of surface and subsurface. Consequently, it is thought that technique developments and applications of these micro/nano NDE in advanced industrial parts together with present nondestructive industry are widely possible hereafter.

  11. Development of an incipient rotor crack detection method by acoustic emission techniques

    International Nuclear Information System (INIS)

    Le Reverend, D.; Massouri, M.H.

    1988-01-01

    The objective of the program presented is to develop a method of detection and monitoring of crack growth in machine rotor by application of acoustic emission techniques. This program is performed by R and D Division of Electricite de France, jointly with INSA de Lyon. The first task of the program is relative to the characterization of acoustic emission during a progressive tensile test performed on a NCT specimen. The second task of the program deals with the experimentation of acoustic emission techniques for the monitoring of a specimen during cycling bending tests. The last task of the program is relative to evaluation of application of acoustic emission techniques for a small rotor integrity monitoring during fatigue rotation tests [fr

  12. A hybrid SEA/modal technique for modeling structural-acoustic interior noise in rotorcraft.

    Science.gov (United States)

    Jayachandran, V; Bonilha, M W

    2003-03-01

    This paper describes a hybrid technique that combines Statistical Energy Analysis (SEA) predictions for structural vibration with acoustic modal summation techniques to predict interior noise levels in rotorcraft. The method was applied for predicting the sound field inside a mock-up of the interior panel system of the Sikorsky S-92 helicopter. The vibration amplitudes of the frame and panel systems were predicted using a detailed SEA model and these were used as inputs to the model of the interior acoustic space. The spatial distribution of the vibration field on individual panels, and their coupling to the acoustic space were modeled using stochastic techniques. Leakage and nonresonant transmission components were accounted for using space-averaged values obtained from a SEA model of the complete structural-acoustic system. Since the cabin geometry was quite simple, the modeling of the interior acoustic space was performed using a standard modal summation technique. Sound pressure levels predicted by this approach at specific microphone locations were compared with measured data. Agreement within 3 dB in one-third octave bands above 40 Hz was observed. A large discrepancy in the one-third octave band in which the first acoustic mode is resonant (31.5 Hz) was observed. Reasons for such a discrepancy are discussed in the paper. The developed technique provides a method for modeling helicopter cabin interior noise in the frequency mid-range where neither FEA nor SEA is individually effective or accurate.

  13. Technique for the focal-length measurement of positive lenses using Fizeau interferometry

    International Nuclear Information System (INIS)

    Pavan Kumar, Yeddanapudi; Chatterjee, Sanjib

    2009-01-01

    We present what we believe is a new technique for the focal-length measurement of positive lenses using Fizeau interferometery. The technique utilizes the Gaussian lens equation. The image distance is measured interferometrically in terms of the radius of curvature of the image-forming wavefront emerging from the lens. The radii of curvature of the image-forming wavefronts corresponding to two different axial object positions of known separation are measured. The focal length of the lens is determined by solving the equations obtained using the Gaussian lens equation for the two object positions. Results obtained for a corrected doublet lens of a nominal focal length of 200.0 mm with a measurement uncertainty of ±2.5% is presented

  14. Microwave Interferometry Based On Open-ended Coaxial Technique for High Sensitivity Liquid Sensing

    Directory of Open Access Journals (Sweden)

    H. Bakli

    2017-10-01

    Full Text Available This paper describes a modified open-ended coaxial technique for microwave dielectric characterization in liquid media. A calibration model is developed to relate the measured transmission coefficient to the local properties of the sample under test. As a demonstration, the permittivity of different sodium chloride solutions is experimentally determined. Accuracies of 0.17% and 0.19% are obtained respectively for the real and imaginary parts of dielectric permittivity at 5.9 GHz.

  15. High-spatial-resolution sub-surface imaging using a laser-based acoustic microscopy technique.

    Science.gov (United States)

    Balogun, Oluwaseyi; Cole, Garrett D; Huber, Robert; Chinn, Diane; Murray, Todd W; Spicer, James B

    2011-01-01

    Scanning acoustic microscopy techniques operating at frequencies in the gigahertz range are suitable for the elastic characterization and interior imaging of solid media with micrometer-scale spatial resolution. Acoustic wave propagation at these frequencies is strongly limited by energy losses, particularly from attenuation in the coupling media used to transmit ultrasound to a specimen, leading to a decrease in the depth in a specimen that can be interrogated. In this work, a laser-based acoustic microscopy technique is presented that uses a pulsed laser source for the generation of broadband acoustic waves and an optical interferometer for detection. The use of a 900-ps microchip pulsed laser facilitates the generation of acoustic waves with frequencies extending up to 1 GHz which allows for the resolution of micrometer-scale features in a specimen. Furthermore, the combination of optical generation and detection approaches eliminates the use of an ultrasonic coupling medium, and allows for elastic characterization and interior imaging at penetration depths on the order of several hundred micrometers. Experimental results illustrating the use of the laser-based acoustic microscopy technique for imaging micrometer-scale subsurface geometrical features in a 70-μm-thick single-crystal silicon wafer with a (100) orientation are presented.

  16. Evaluating autonomous acoustic surveying techniques for rails in tidal marshes

    Science.gov (United States)

    Stiffler, Lydia L.; Anderson, James T.; Katzner, Todd

    2018-01-01

    There is a growing interest toward the use of autonomous recording units (ARUs) for acoustic surveying of secretive marsh bird populations. However, there is little information on how ARUs compare to human surveyors or how best to use ARU data that can be collected continuously throughout the day. We used ARUs to conduct 2 acoustic surveys for king (Rallus elegans) and clapper rails (R. crepitans) within a tidal marsh complex along the Pamunkey River, Virginia, USA, during May–July 2015. To determine the effectiveness of an ARU in replacing human personnel, we compared results of callback point‐count surveys with concurrent acoustic recordings and calculated estimates of detection probability for both rail species combined. The success of ARUs at detecting rails that human observers recorded decreased with distance (P ≤ 0.001), such that at 75 m, only 34.0% of human‐detected rails were detected by the ARU. To determine a subsampling scheme for continuous ARU data that allows for effective surveying of presence and call rates of rails, we used ARUs to conduct 15 continuous 48‐hr passive surveys, generating 720 hr of recordings. We established 5 subsampling periods of 5, 10, 15, 30, and 45 min to evaluate ARU‐based presence and vocalization detections of rails compared with each of the full 60‐min sampling of ARU‐based detection of rails. All subsampling periods resulted in different (P ≤ 0.001) detection rates and unstandardized vocalization rates compared with the hourly sampling period. However, standardized vocalization counts from the 30‐min subsampling period were not different from vocalization counts of the full hourly sampling period. When surveying rail species in estuarine environments, species‐, habitat‐, and ARU‐specific limitations to ARU sampling should be considered when making inferences about abundances and distributions from ARU data. 

  17. Intelligent acoustic data fusion technique for information security analysis

    Science.gov (United States)

    Jiang, Ying; Tang, Yize; Lu, Wenda; Wang, Zhongfeng; Wang, Zepeng; Zhang, Luming

    2017-08-01

    Tone is an essential component of word formation in all tonal languages, and it plays an important role in the transmission of information in speech communication. Therefore, tones characteristics study can be applied into security analysis of acoustic signal by the means of language identification, etc. In speech processing, fundamental frequency (F0) is often viewed as representing tones by researchers of speech synthesis. However, regular F0 values may lead to low naturalness in synthesized speech. Moreover, F0 and tone are not equivalent linguistically; F0 is just a representation of a tone. Therefore, the Electroglottography (EGG) signal is collected for deeper tones characteristics study. In this paper, focusing on the Northern Kam language, which has nine tonal contours and five level tone types, we first collected EGG and speech signals from six natural male speakers of the Northern Kam language, and then achieved the clustering distributions of the tone curves. After summarizing the main characteristics of tones of Northern Kam, we analyzed the relationship between EGG and speech signal parameters, and laid the foundation for further security analysis of acoustic signal.

  18. The Use of Structural-Acoustic Techniques to Assess Potential Structural Damage From Sonic Booms

    Science.gov (United States)

    Garrelick, Joel; Martini, Kyle

    1996-01-01

    The potential impact of supersonic operations includes structural damage from the sonic boom overpressure. This paper describes a study of how structural-acoustic modeling and testing techniques may be used to assess the potential for such damage in the absence of actual flyovers. Procedures are described whereby transfer functions relating structural response to sonic boom signature may be obtained with a stationary acoustic source and appropriate data processing. Further, by invoking structural-acoustic reciprocity, these transfer functions may also be acquired by measuring the radiated sound from the structure under a mechanical drive. The approach is based on the fundamental assumption of linearity, both with regard to the (acoustic) propagation of the boom in the vicinity of the structure and to the structure's response. Practical issues revolve around acoustic far field and source directivity requirements. The technique was implemented on a specially fabricated test structure at Edwards AFB, CA with the support of Wyle Laboratories, Inc. Blank shots from a cannon served as our acoustic source and taps from an instrumented hammer generated the mechanical drive. Simulated response functions were constructed. Results of comparisons with corresponding measurements recorded during dedicated supersonic flyovers with F-15 aircraft are presented for a number of sensor placements.

  19. Evaluating autonomous acoustic surveying techniques for rails in tidal marshes

    Science.gov (United States)

    Stiffler, Lydia L.; Anderson, James T.; Katzner, Todd

    2018-01-01

    There is a growing interest toward the use of autonomous recording units (ARUs) for acoustic surveying of secretive marsh bird populations. However, there is little information on how ARUs compare to human surveyors or how best to use ARU data that can be collected continuously throughout the day. We used ARUs to conduct 2 acoustic surveys for king (Rallus elegans) and clapper rails (R. crepitans) within a tidal marsh complex along the Pamunkey River, Virginia, USA, during May–July 2015. To determine the effectiveness of an ARU in replacing human personnel, we compared results of callback point‐count surveys with concurrent acoustic recordings and calculated estimates of detection probability for both rail species combined. The success of ARUs at detecting rails that human observers recorded decreased with distance (P ≤ 0.001), such that at of human‐recorded rails also were detected by the ARU, but at >75 m, only 34.0% of human‐detected rails were detected by the ARU. To determine a subsampling scheme for continuous ARU data that allows for effective surveying of presence and call rates of rails, we used ARUs to conduct 15 continuous 48‐hr passive surveys, generating 720 hr of recordings. We established 5 subsampling periods of 5, 10, 15, 30, and 45 min to evaluate ARU‐based presence and vocalization detections of rails compared with each of the full 60‐min sampling of ARU‐based detection of rails. All subsampling periods resulted in different (P ≤ 0.001) detection rates and unstandardized vocalization rates compared with the hourly sampling period. However, standardized vocalization counts from the 30‐min subsampling period were not different from vocalization counts of the full hourly sampling period. When surveying rail species in estuarine environments, species‐, habitat‐, and ARU‐specific limitations to ARU sampling should be considered when making inferences about abundances and distributions from ARU data. 

  20. Vibration insensitive interferometry

    Science.gov (United States)

    Millerd, James; Brock, Neal; Hayes, John; Kimbrough, Brad; North-Morris, Michael; Wyant, James C.

    2017-11-01

    The largest limitation of phase-shifting interferometry for optical testing is the sensitivity to the environment, both vibration and air turbulence. An interferometer using temporal phase-shifting is very sensitive to vibration because the various phase shifted frames of interferometric data are taken at different times and vibration causes the phase shifts between the data frames to be different from what is desired. Vibration effects can be reduced by taking all the phase shifted frames simultaneously and turbulence effects can be reduced by averaging many measurements. There are several techniques for simultaneously obtaining several phase-shifted interferograms and this paper will discuss two such techniques: 1) Simultaneous phase-shifting interferometry on a single detector array (PhaseCam) and 2) Micropolarizer phase-shifting array. The application of these techniques for the testing of large optical components, measurement of vibrational modes, the phasing of segmented optical components, and the measurement of deformations of large diffuse structures is described.

  1. Using acoustic emission technique to monitor fractures on the analogous pressure pipes

    International Nuclear Information System (INIS)

    Zhang Lichen

    1989-01-01

    By using the acoustic emission technique to monitor the fractures on analogous pressure pipes of the primary circuit which has had cracks and loading with pressure was investigated. The dynamical process, from cracking to fracturing, was recorded by the acoustic emission technique. Comparing with the conventional method, this method gives more informations, such as pre-cracking, cracking growing, fast fracturing and the pressure values at different phases. During testing time a microcomputer was used for real-time data processing and locating the fracturing position. These data are useful for the mechanical analysis of the reactor components

  2. Phase Referencing in Optical Interferometry

    OpenAIRE

    Filho, Mercedes E.; Garcia, Paulo; Duvert, Gilles; Duchene, Gaspard; Thiebaut, Eric; Young, John; Absil, Olivier; Berger, Jean-Phillipe; Beckert, Thomas; Hoenig, Sebastian; Schertl, Dieter; Weigelt, Gerd; Testi, Leonardo; Tatuli, Eric; Borkowski, Virginie

    2008-01-01

    One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and optical interferometry are at the two extremes of phase corruption by the atmosphere. While in radio it is possible to obtain calibrated phases for the science objects, in the optical this is currently not possible. Instead, optical interferometry has relied on closure phase techniques to produce...

  3. Effects of melody and technique on acoustical and musical features of western operatic singing voices.

    Science.gov (United States)

    Larrouy-Maestri, Pauline; Magis, David; Morsomme, Dominique

    2014-05-01

    The operatic singing technique is frequently used in classical music. Several acoustical parameters of this specific technique have been studied but how these parameters combine remains unclear. This study aims to further characterize the Western operatic singing technique by observing the effects of melody and technique on acoustical and musical parameters of the singing voice. Fifty professional singers performed two contrasting melodies (popular song and romantic melody) with two vocal techniques (with and without operatic singing technique). The common quality parameters (energy distribution, vibrato rate, and extent), perturbation parameters (standard deviation of the fundamental frequency, signal-to-noise ratio, jitter, and shimmer), and musical features (fundamental frequency of the starting note, average tempo, and sound pressure level) of the 200 sung performances were analyzed. The results regarding the effect of melody and technique on the acoustical and musical parameters show that the choice of melody had a limited impact on the parameters observed, whereas a particular vocal profile appeared depending on the vocal technique used. This study confirms that vocal technique affects most of the parameters examined. In addition, the observation of quality, perturbation, and musical parameters contributes to a better understanding of the Western operatic singing technique. Copyright © 2014 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

  4. Utilisation of acoustic emission technique to monitor lubrication condition in a low speed bearing

    International Nuclear Information System (INIS)

    Nordin Jamaludin; Mohd Jailani Mohd Nor

    2003-01-01

    Monitoring of lubrication condition in rolling element bearings through the use of vibration analysis is an established technique. However, this success has not mirrored at low rotational speeds. At low speeds the energy generated from the poor lubricated bearing lubrication might not show as an obvious change in signature and thus become undetectable using conventional vibration measuring equipment. This paper presents an investigation into the applicability of acoustic emission technique and analysis for detecting poorly lubricated bearing rotating at a speed of 1.12 rpm. Investigations were centered on a test-rig designed to simulate the real bearing used in the field. The variation of lubricant amount in the low-speed bearing was successfully monitored using a new developed method known as pulse injection technique (PIT). The PIT technique was based on acoustic emission method. The technique involved transmitting a Dirac pulse to the test bearing via a transmitting acoustic emission sensor while the bearing was in operation. Analysing the captured acoustic emission signatures using established statistical method could differentiate between properly and poorly lubricated bearing. (Author)

  5. Application of acoustic emission, as non destructive testing technique, to nuclear components inspection

    International Nuclear Information System (INIS)

    Sanchez Miro, J.J.

    1980-01-01

    A panorama of actual state of acoustic emission as non destructive testing technique, from stand point of its safety applications to nuclear reactor is offered. In first place the physic grounds of acoustic emission phenomenon is briefly exposed. After we speak about the experimental methods for detection, and overall is made an explanation of the problems which are found during the application of this technology to on-line inspection of nuclear oower plants. It is hoped that this repport makes a contribution in the sense of to create a favourable atmosphere toward the introduction in our country of this important technique, and concretely within the nuclear power industry. In this last field the employ of acoustic emission is overcoming the experimental stage. (author)

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

    Science.gov (United States)

    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.

  7. Advanced signal processing techniques for acoustic detection of sodium/water reaction

    International Nuclear Information System (INIS)

    Yughay, V.S.; Gribok, A.V.; Volov, A.N.

    1997-01-01

    In this paper results of development of a neural network technique for processing of acoustic background noise and injection noise of various media (argon, water steam, hydrogen) at test rigs and industrial steam generator are presented. (author). 3 refs, 9 figs, 3 tabs

  8. A line array based near field imaging technique for characterising acoustical properties of elongated targets

    NARCIS (Netherlands)

    Driessen, F.P.G.

    1995-01-01

    With near field imaging techniques the acoustical pressure waves at distances other than the recorded can be calculated. Normally, acquisition on a two dimensional plane is necessary and extrapolation is performed by a Rayleigh integral. A near field single line instead of two dimensional plane

  9. Characterization of the multi-component driving land subsidence using Persistent Scatterer Interferometry technique: the Ravenna case of study (Italy)

    Science.gov (United States)

    Bonì, Roberta; Fiaschi, Simone; Calcaterra, Domenico; Di Martire, Diego; Ibrahim, Ahmed; Meisina, Claudia; Perini, Luisa; Ramondini, Massimo; Tessitore, Serena; Floris, Mario

    2015-04-01

    Land subsidence represents a kind of hazard, which affects an increasing number of worldwide regions, densely populated, causing damage to the environment and infrastructures. Settlements can be related to multiple processes both natural and anthropic (i.e. vadose zone processes, soil consolidation, aquifer compaction, solid and fluid extraction and load-induced compaction) which take place at different spatio-temporal scale. Over the last decades, advanced subsidence studies exploited Synthetic-Aperture Radar (SAR) data, a recent remote sensing tool, to investigate land subsidence phenomena around the world. In particular, Persistent Scatterer Interferometry (PSI) technique, allowing a quantitative estimation at high resolution of the surface deformations, has already been successfully applied to monitor the phenomenon evolution; PSI measurements represent the cumulative displacement, deriving from the contribution of natural and anthropic components, both superficial and deep. The overlapping of several causative factors makes more difficult to accurately interpret the resulting deformations; therefore, it is essential to implement a suitable methodology to distinguish the shallow and deep components of motion. The aim of our research is to introduce a PSI-based approach not only to monitoring but also to understand the land subsidence mechanism, in order to disentangle the natural and anthropic components of motion. The methodology consists of three main phases: 1) Post-processing elaborations (i.e. interpolation of the cumulated displacements and isokinetics map implementation); 2) Characterization of the subsidence areas (i.e. subsidence pattern recognition by means of automatic time series classification); 3) Mechanisms recognition (i.e. identification of the predisposing and triggering factors and comparison with lito-technical model of subsoil, and with earth measurements). In this work, the methodology has been applied to the Ravenna area, Italy, using

  10. Fundamental and assessment of concrete structure monitoring by using acoustic emission technique testing: A review

    Science.gov (United States)

    Desa, M. S. M.; Ibrahim, M. H. W.; Shahidan, S.; Ghadzali, N. S.; Misri, Z.

    2018-04-01

    Acoustic emission (AE) technique is one of the non-destructive (NDT) testing, where it can be used to determine the damage of concrete structures such as crack, corrosion, stability, sensitivity, as structure monitoring and energy formed within cracking opening growth in the concrete structure. This article gives a comprehensive review of the acoustic emission (AE) technique testing due to its application in concrete structure for structural health monitoring (SHM). Assessment of AE technique used for structural are reviewed to give the perception of its structural engineering such as dam, bridge and building, where the previous research has been reviewed based on AE application. The assessment of AE technique focusing on basic fundamental of parametric and signal waveform analysis during analysis process and its capability in structural monitoring. Moreover, the assessment and application of AE due to its function have been summarized and highlighted for future references

  11. Acoustic impedance rhinometry (AIR): a technique for monitoring dynamic changes in nasal congestion

    International Nuclear Information System (INIS)

    Patuzzi, Robert; Cook, Alison

    2014-01-01

    We describe a simple and inexpensive method for monitoring nasal air flow resistance using measurement of the small-signal acoustic input impedance of the nasal passage, similar to the audiological measurement of ear drum compliance with acoustic tympanometry. The method requires generation of a fixed sinusoidal volume–velocity stimulus using ear-bud speakers, and an electret microphone to monitor the resultant pressure fluctuation in the nasal passage. Both are coupled to the nose via high impedance silastic tubing and a small plastic nose insert. The acoustic impedance is monitored in real-time using a laptop soundcard and custom-written software developed in LabView 7.0 (National Instruments). The compact, lightweight equipment and fast time resolution lends the technique to research into the small and rapid reflexive changes in nasal resistance caused by environmental and local neurological influences. The acoustic impedance rhinometry technique has the potential to be developed for use in a clinical setting, where the need exists for a simple and inexpensive objective nasal resistance measurement technique. (paper)

  12. Non-destructive evaluation of nuclear material storage container integrity using an acoustic technique

    International Nuclear Information System (INIS)

    Miller, R.F.; Pechersky, M.J.; Raju, P.K.

    1994-01-01

    A non-intrusive method for determining the gas mixture in a sealed container using acoustics has been conceived. Analysis has shown that it is possible to both excite the acoustic resonance of the gas cavity, and detect when resonance occurs from the outside surface of the container. The resonant frequency of the acoustic cavity is dependent on the molecular weight of the gas that fills it. A change in the mixture of gases within the cavity alters the gas molecular weight and can produce a detectable change in the resonant frequency of the cavity. This concept provides a method of monitoring and/or analyzing the gas mixture in a sealed container without taking physical samples. An advantage of this technique is that it eliminates safety and contamination risks associated with breaching a pressure boundary and taking a sample of potentially hazardous gases in order to monitor or analyze the mixture

  13. Online laboratory evaluation of seeding-machine application by an acoustic technique

    Energy Technology Data Exchange (ETDEWEB)

    Karimi, H.; Navid, H.; Mahmoudi, A.

    2015-07-01

    Researchers and planter manufacturers have been working closely to develop an automated system for evaluating performance of seeding. In the present study, an innovative use of acoustic signal for laboratory evaluation of seeding-machine application is described. Seed detection technique of the proposed system was based on a rising voltage value that a microphone sensed in each impaction of seeds to a steel plate. Online determining of seed spacing was done with a script which was written in MATLAB software. To evaluate the acoustic system with desired seed spacing, a testing rig was designed. Seeds of wheat, corn and pelleted tomato were used as experimental material. Typical seed patterns were positioned manually on a belt stand with different spacing patterns. When the belt was running, the falling seeds from the end point of the belt impacted to the steel plate, and their acoustic signal was sensed by the microphone. In each impact, data was processed and spacing between the seeds was automatically obtained. Coefficient of determination of gathered data from the belt system and the corresponding seeds spacing measured with the acoustic system in all runs was about 0.98. This strong correlation indicates that the acoustic system worked well in determining the seeds spacing. (Author)

  14. Vibro-acoustic condition monitoring of Internal Combustion Engines: A critical review of existing techniques

    Science.gov (United States)

    Delvecchio, S.; Bonfiglio, P.; Pompoli, F.

    2018-01-01

    This paper deals with the state-of-the-art strategies and techniques based on vibro-acoustic signals that can monitor and diagnose malfunctions in Internal Combustion Engines (ICEs) under both test bench and vehicle operating conditions. Over recent years, several authors have summarized what is known in critical reviews mainly focused on reciprocating machines in general or on specific signal processing techniques: no attempts to deal with IC engine condition monitoring have been made. This paper first gives a brief summary of the generation of sound and vibration in ICEs in order to place further discussion on fault vibro-acoustic diagnosis in context. An overview of the monitoring and diagnostic techniques described in literature using both vibration and acoustic signals is also provided. Different faulty conditions are described which affect combustion, mechanics and the aerodynamics of ICEs. The importance of measuring acoustic signals, as opposed to vibration signals, is due since the former seem to be more suitable for implementation on on-board monitoring systems in view of their non-intrusive behaviour, capability in simultaneously capturing signatures from several mechanical components and because of the possibility of detecting faults affecting airborne transmission paths. In view of the recent needs of the industry to (-) optimize component structural durability adopting long-life cycles, (-) verify the engine final status at the end of the assembly line and (-) reduce the maintenance costs monitoring the ICE life during vehicle operations, monitoring and diagnosing system requests are continuously growing up. The present review can be considered a useful guideline for test engineers in understanding which types of fault can be diagnosed by using vibro-acoustic signals in sufficient time in both test bench and operating conditions and which transducer and signal processing technique (of which the essential background theory is here reported) could be

  15. Distributed acoustic sensing technique and its field trial in SAGD well

    Science.gov (United States)

    Han, Li; He, Xiangge; Pan, Yong; Liu, Fei; Yi, Duo; Hu, Chengjun; Zhang, Min; Gu, Lijuan

    2017-10-01

    Steam assisted gravity drainage (SAGD) is a very promising way for the development of heavy oil, extra heavy oil and tight oil reservoirs. Proper monitoring of the SAGD operations is essential to avoid operational issues and improve efficiency. Among all the monitoring techniques, micro-seismic monitoring and related interpretation method can give useful information about the steam chamber development and has been extensively studied. Distributed acoustic sensor (DAS) based on Rayleigh backscattering is a newly developed technique that can measure acoustic signal at all points along the sensing fiber. In this paper, we demonstrate a DAS system based on dual-pulse heterodyne demodulation technique and did field trial in SAGD well located in Xinjiang Oilfield, China. The field trail results validated the performance of the DAS system and indicated its applicability in steam-chamber monitoring and hydraulic monitoring.

  16. Spatial Techniques to Visualize Acoustic Comfort along Cultural and Heritage Routes for a World Heritage City

    Directory of Open Access Journals (Sweden)

    Ni Sheng

    2015-07-01

    Full Text Available This paper proposes to visualize acoustic comfort along tourist routes. Route-based tourism is crucial to the sustainability of tourism development in historic areas. Applying the concept of route-based tourism to guide tourists rambling along cultural and heritage routes can relieve overcrowded condition at hot scenic spots and increase the overall carrying capacity of the city. However, acoustic comfort along tourist routes is rarely addressed in academic studies and decision-making. Taking Macao as an example, this paper has studied pedestrian exposure to traffic noise along the cultural and heritage routes. The study is based on a GIS-based traffic noise model system with a high spatial resolution down to individual buildings along both sides of the street. Results show that tourists suffer from excessive traffic noise at certain sites, which may have negative impact on the promotion of route-based tourism in the long run. In addition, it is found that urban growth affects urban form and street layout, which in turn affect traffic flow and acoustic comfort in urban area. The present study demonstrates spatial techniques to visualize acoustic comfort along tourist routes, and the techniques are foreseen to be used more frequently to support effective tourism planning in the future.

  17. UF6 Density and Mass Flow Measurements for Enrichment Plants using Acoustic Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Good, Morris S.; Smith, Leon E.; Warren, Glen A.; Jones, Anthony M.; Ramuhalli, Pradeep; Roy, Surajit; Moran, Traci L.; Denslow, Kayte M.; Longoni, Gianluca

    2017-09-01

    A key enabling capability for enrichment plant safeguards being considered by the International Atomic Energy Agency (IAEA) is high-accuracy, noninvasive, unattended measurement of UF6 gas density and mass flow rate. Acoustic techniques are currently used to noninvasively monitor gas flow in industrial applications; however, the operating pressures at gaseous centrifuge enrichment plants (GCEPs) are roughly two orders magnitude below the capabilities of commercial instrumentation. Pacific Northwest National Laboratory is refining acoustic techniques for estimating density and mass flow rate of UF6 gas in scenarios typical of GCEPs, with the goal of achieving 1% measurement accuracy. Proof-of-concept laboratory measurements using a surrogate gas for UF6 have demonstrated signatures sensitive to gas density at low operating pressures such as 10–50 Torr, which were observed over the background acoustic interference. Current efforts involve developing a test bed for conducting acoustic measurements on flowing SF6 gas at representative flow rates and pressures to ascertain the viability of conducting gas flow measurements under these conditions. Density and flow measurements will be conducted to support the evaluation. If successful, the approach could enable an unattended, noninvasive approach to measure mass flow in unit header pipes of GCEPs.

  18. Time domain localization technique with sparsity constraint for imaging acoustic sources

    Science.gov (United States)

    Padois, Thomas; Doutres, Olivier; Sgard, Franck; Berry, Alain

    2017-09-01

    This paper addresses source localization technique in time domain for broadband acoustic sources. The objective is to accurately and quickly detect the position and amplitude of noise sources in workplaces in order to propose adequate noise control options and prevent workers hearing loss or safety risk. First, the generalized cross correlation associated with a spherical microphone array is used to generate an initial noise source map. Then a linear inverse problem is defined to improve this initial map. Commonly, the linear inverse problem is solved with an l2 -regularization. In this study, two sparsity constraints are used to solve the inverse problem, the orthogonal matching pursuit and the truncated Newton interior-point method. Synthetic data are used to highlight the performances of the technique. High resolution imaging is achieved for various acoustic sources configurations. Moreover, the amplitudes of the acoustic sources are correctly estimated. A comparison of computation times shows that the technique is compatible with quasi real-time generation of noise source maps. Finally, the technique is tested with real data.

  19. Acoustic emission

    International Nuclear Information System (INIS)

    Nichols, R.W.

    1976-01-01

    The volume contains six papers which together provide an overall review of the inspection technique known as acoustic emission or stress wave emission. The titles are: a welder's introduction to acoustic emission technology; use of acoustic emission for detection of defects as they arise during fabrication; examples of laboratory application and assessment of acoustic emission in the United Kingdom; (Part I: acoustic emission behaviour of low alloy steels; Part II: fatigue crack assessment from proof testing and continuous monitoring); inspection of selected areas of engineering structures by acoustic emission; Japanese experience in laboratory and practical applications of acoustic emission to welded structures; and ASME acoustic emission code status. (U.K.)

  20. Understanding seafloor morphology using remote high frequency acoustic methods: An appraisal to modern techniques and its effectiveness

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.

    Content-Type text/plain; charset=UTF-8 179 Understanding seafloor morphology using remote high frequency acoustic methods: an appraisal to modern techniques and its effectiveness Bishwajit Chakraborty National institute of Oceanography.... The two third of the earth surface i.e. 362 million square km (70 %) is covered by the ocean. In order to understand the seafloor various methods like: application of remote acoustic techniques, seafloor photographic and geological sampling techniques...

  1. Computational reduction techniques for numerical vibro-acoustic analysis of hearing aids

    DEFF Research Database (Denmark)

    Creixell Mediante, Ester

    . In this thesis, several challenges encountered in the process of modelling and optimizing hearing aids are addressed. Firstly, a strategy for modelling the contacts between plastic parts for harmonic analysis is developed. Irregularities in the contact surfaces, inherent to the manufacturing process of the parts....... Secondly, the applicability of Model Order Reduction (MOR) techniques to lower the computational complexity of hearing aid vibro-acoustic models is studied. For fine frequency response calculation and optimization, which require solving the numerical model repeatedly, a computational challenge...... is encountered due to the large number of Degrees of Freedom (DOFs) needed to represent the complexity of the hearing aid system accurately. In this context, several MOR techniques are discussed, and an adaptive reduction method for vibro-acoustic optimization problems is developed as a main contribution. Lastly...

  2. Opto-acoustic technique to evaluate adhesion strength of thin-film systems

    Directory of Open Access Journals (Sweden)

    S. Yoshida

    2012-06-01

    Full Text Available An opto-acoustic technique is proposed to evaluate the adhesion strength of thin film systems at the film-substrate interface. The thin-film system to be examined is configured as an end-mirror of a Michelson interferometer, and driven from the rear with an acoustic transducer at audible frequencies. The amplitude of the resultant oscillation of the film is quantified as the variation in the contrast of the interferometric fringe pattern observed with a digital camera at 30 frames/s. As a proof of concept, experiment has been conducted with the use of a pair of strongly and weakly adhered Au-coated Si-wafer specimens. The technique successfully differentiates the adhesion strength of the specimens.

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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

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

    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 × 10 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 range

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

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Moiz; Yousefi, Siavash; Xing, Lei, E-mail: lei@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305-5847 (United States); Xiang, Liangzhong [Center for Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019-1101 (United States)

    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

  6. Comparative evaluation of acoustic techniques for detection of damages in historical wood

    Czech Academy of Sciences Publication Activity Database

    Kloiber, Michal; Reinprecht, L.; Hrivnák, Jaroslav; Tippner, J.

    2016-01-01

    Roč. 20, July-August (2016), s. 622-631 ISSN 1296-2074 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0060; GA MŠk(CZ) LO1219; GA MK(CZ) DG16P02M026 Keywords : historical wood * damages * inspection * acoustic techniques * mechanical properties Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 1.838, year: 2016 http://www.sciencedirect.com/science/article/pii/S1296207416300103

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

    Science.gov (United States)

    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.

  8. Viscoelastic assessment of anal canal function using acoustic reflectometry: a clinically useful technique.

    Science.gov (United States)

    Mitchell, Peter J; Klarskov, Niels; Telford, Karen J; Hosker, Gordon L; Lose, Gunnar; Kiff, Edward S

    2012-02-01

    Anal acoustic reflectometry is a new reproducible technique that allows a viscoelastic assessment of anal canal function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, opening and closing elastance, and hysteresis. The aim of this study was to assess whether the parameters measured in anal acoustic reflectometry are clinically valid between continent and fecally incontinent subjects. This was an age- and sex-matched study of continent and incontinent women. The study was conducted at a university teaching hospital. One hundred women (50 with fecal incontinence and 50 with normal bowel control) were included in the study. Subjects were age matched to within 5 years. Parameters measured with anal acoustic reflectometry and manometry were compared between incontinent and continent groups using a paired t test. Diagnostic accuracy was assessed by the use of receiver operator characteristic curves. Four of the 5 anal acoustic reflectometry parameters at rest were significantly different between continent and incontinent women (eg, opening pressure in fecally incontinent subjects was 31.6 vs 51.5 cm H2O in continent subjects, p = 0.0001). Both anal acoustic reflectometry parameters of squeeze opening pressure and squeeze opening elastance were significantly reduced in the incontinent women compared with continent women (50 vs 99.1 cm H2O, p = 0.0001 and 1.48 vs 1.83 cm H2O/mm, p = 0.012). In terms of diagnostic accuracy, opening pressure at rest measured by reflectometry was significantly superior in discriminating between continent and incontinent women in comparison with resting pressure measured with manometry (p = 0.009). Anal acoustic reflectometry is a new, clinically valid technique in the assessment of continent and incontinent subjects. This technique, which assesses the response of the anal canal to distension and relaxation, provides a detailed viscoelastic assessment of anal canal function. This technique

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Rubaiyet Iftekharul Haque

    2015-10-01

    Full Text Available 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.

  11. Performance analysis of passive time reversal communication technique for multipath interference in shallow sea acoustic channel

    Science.gov (United States)

    Kida, Yukihiro; Shimura, Takuya; Deguchi, Mitsuyasu; Watanabe, Yoshitaka; Ochi, Hiroshi; Meguro, Koji

    2017-07-01

    In this study, the performance of passive time reversal (PTR) communication techniques in multipath rich underwater acoustic environments is investigated. It is recognized empirically and qualitatively that a large number of multipath arrivals could generally raise the demodulation result of PTR. However, the relationship between multipath and the demodulation result is hardly evaluated quantitatively. In this study, the efficiency of the PTR acoustic communication techniques for multipath interference cancelation was investigated quantitatively by applying a PTR-DFE (decision feed-back filter) scheme to a synthetic dataset of a horizontal underwater acoustic channel. Mainly, in this study, we focused on the relationship between the signal-to-interference ratio (SIR) of datasets and the output signal-to-noise ratio (OSNR) of demodulation results by a parametric study approach. As a result, a proportional relation between SIR and OSNR is confirmed in low-SNR datasets. It was also found that PTR has a performance limitation, that is OSNR converges to a typical value depending on the number of receivers. In conclusion, results indicate that PTR could utilize the multipath efficiently and also withstand the negative effects of multipath interference at a given limitation.

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

    Science.gov (United States)

    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.

  13. Basics of interferometry

    CERN Document Server

    Hariharan, P

    1992-01-01

    This book is for those who have some knowledge of optics, but little or no previous experience in interferometry. Accordingly, the carefully designed presentation helps readers easily find and assimilate the interferometric techniques they need for precision measurements. Mathematics is held to a minimum, and the topics covered are also summarized in capsule overviews at the beginning and end of each chapter. Each chapter also contains a set of worked problems that give a feel for numbers.The first five chapters present a clear tutorial review of fundamentals. Chapters six and seven discus

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  16. Phase estimation in optical interferometry

    CERN Document Server

    Rastogi, Pramod

    2014-01-01

    Phase Estimation in Optical Interferometry covers the essentials of phase-stepping algorithms used in interferometry and pseudointerferometric techniques. It presents the basic concepts and mathematics needed for understanding the phase estimation methods in use today. The first four chapters focus on phase retrieval from image transforms using a single frame. The next several chapters examine the local environment of a fringe pattern, give a broad picture of the phase estimation approach based on local polynomial phase modeling, cover temporal high-resolution phase evaluation methods, and pre

  17. Acoustic emission technique for characterisation of deformation, fatigue, fracture and phase transformation and for leak detection with high sensitivity- our experiences

    International Nuclear Information System (INIS)

    Jayakumar, T.; Mukhopadhyay, C.K.; Baldev Raj

    1996-01-01

    Acoustic emission technique has been used for studying tensile deformation, fracture behaviour, detection and assessment of fatigue crack growth and α-martensite phase transformation in austenitic alloys. A methodology for amplification of weak acoustic emission signals has been established. Acoustic emission technique with advanced spectral analysis has enabled detection with high sensitivity of minute leaks in noisy environments. (author)

  18. Fundamental physics research and neutron interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Ioffe, A. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1996-08-01

    The possibility of the use of an extremely sensitive neutron interferometry technique for the study of electromagnetic structure of the neutron and the parity non-conservative effects in neutron spin rotation is discussed. (author)

  19. Novel Polarimetric SAR Interferometry Algorithms, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Polarimetric radar interferometry (PolInSAR) is a new SAR imaging mode that is rapidly becoming an important technique for bare earth topographic mapping, tree...

  20. Development of Very Long Baseline Interferometry (VLBI) techniques in New Zealand: Array simulation, image synthesis and analysis

    Science.gov (United States)

    Weston, S. D.

    2008-04-01

    This thesis presents the design and development of a process to model Very Long Base Line Interferometry (VLBI) aperture synthesis antenna arrays. In line with the Auckland University of Technology (AUT) Institute for Radiophysics and Space Research (IRSR) aims to develop the knowledge, skills and experience within New Zealand, extensive use of existing radio astronomical software has been incorporated into the process namely AIPS (Astronomical Imaging Processing System), MIRIAD (a radio interferometry data reduction package) and DIFMAP (a program for synthesis imaging of visibility data from interferometer arrays of radio telescopes). This process has been used to model various antenna array configurations for two proposed New Zealand sites for antenna in a VLBI array configuration with existing Australian facilities and a passable antenna at Scott Base in Antarctica; and the results are presented in an attempt to demonstrate the improvement to be gained by joint trans-Tasman VLBI observation. It is hoped these results and process will assist the planning and placement of proposed New Zealand radio telescopes for cooperation with groups such as the Australian Long Baseline Array (LBA), others in the Pacific Rim and possibly globally; also potential future involvement of New Zealand with the SKA. The developed process has also been used to model a phased building schedule for the SKA in Australia and the addition of two antennas in New Zealand. This has been presented to the wider astronomical community via the Royal Astronomical Society of New Zealand Journal, and is summarized in this thesis with some additional material. A new measure of quality ("figure of merit") for comparing the original model image and final CLEAN images by utilizing normalized 2-D cross correlation is evaluated as an alternative to the existing subjective visual operator image comparison undertaken to date by other groups. This new unit of measure is then used ! in the presentation of the

  1. Techniques to assess acoustic-structure interaction in liquid rocket engines

    Science.gov (United States)

    Davis, R. Benjamin

    Acoustoelasticity is the study of the dynamic interaction between elastic structures and acoustic enclosures. In this dissertation, acoustoelasticity is considered in the context of liquid rocket engine design. The techniques presented here can be used to determine which forcing frequencies are important in acoustoelastic systems. With a knowledge of these frequencies, an analyst can either find ways to attenuate the excitation at these frequencies or alter the system in such a way that the prescribed excitations do result in a resonant condition. The end result is a structural component that is less susceptible to failure. The research scope is divided into three parts. In the first part, the dynamics of cylindrical shells submerged in liquid hydrogen (LH2) and liquid oxygen (LOX) are considered. The shells are bounded by rigid outer cylinders. This configuration gives rise to two fluid-filled cavities---an inner cylindrical cavity and an outer annular cavity. Such geometries are common in rocket engine design. The natural frequencies and modes of the fluid-structure system are computed by combining the rigid wall acoustic cavity modes and the in vacuo structural modes into a system of coupled ordinary differential equations. Eigenvalue veering is observed near the intersections of the curves representing natural frequencies of the rigid wall acoustic and the in vacuo structural modes. In the case of a shell submerged in LH2, system frequencies near these intersections are as much as 30% lower than the corresponding in vacuo structural frequencies. Due to its high density, the frequency reductions in the presence of LOX are even more dramatic. The forced responses of a shell submerged in LH2 and LOX while subject to a harmonic point excitation are also presented. The responses in the presence of fluid are found to be quite distinct from those of the structure in vacuo. In the second part, coupled mode theory is used to explore the fundamental features of

  2. Investigating deformation processes in AM60 magnesium alloy using the acoustic emission technique

    International Nuclear Information System (INIS)

    Mathis, K.; Chmelik, F.; Janecek, M.; Hadzima, B.; Trojanova, Z.; Lukac, P.

    2006-01-01

    Microstructure changes in an AM60 magnesium alloy were monitored using the acoustic emission (AE) technique during tensile tests in the temperature range from 20 to 300 deg. C. The correlation of the AE signal and the deformation processes is discussed. It is shown, using transmission electron and light microscopy, that the character of the AE response is associated with various modes of mechanical twinning at lower temperatures, whereas at higher temperatures also the influence of non-basal dislocations on the AE response must be taken into account

  3. Structural investigation and simulation of acoustic properties of some tellurite glasses using artificial intelligence technique

    International Nuclear Information System (INIS)

    Gaafar, M.S.; Abdeen, Mostafa A.M.; Marzouk, S.Y.

    2011-01-01

    Research highlights: → Simulation the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). → The glass network is strengthened by enhancing the linkage of Te-O chains. The tellurite network will also come to homogenization, because of uniform distribution of Nb 5+ ions among the Te-O chains, though some of the tellurium-oxide polyhedra still link each other in edge sharing. → Excellent agreements between the measured values and the predicted values were obtained for over 50 different tellurite glass compositions. → The model we designed gives a better agreement as compared with Makishima and Machenzie model. - Abstract: The developments in the field of industry raise the need for simulating the acoustic properties of glass materials before melting raw material oxides. In this paper, we are trying to simulate the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). The artificial neural network (ANN) technique is introduced in the current study to simulate and predict important parameters such as density, longitudinal and shear ultrasonic velocities and elastic moduli (longitudinal and shear moduli). The ANN results were found to be in successful good agreement with those experimentally measured parameters. Then the presented ANN model is used to predict the acoustic properties of some new tellurite glasses. For this purpose, four glass systems xNb 2 O 5 -(1 - x)TeO 2 , 0.1PbO-xNb 2 O 5 -(0.9 - x)TeO 2 , 0.2PbO-xNb 2 O 5 -(0.8 - x)TeO 2 and 0.05Bi 2 O 3 -xNb 2 O 5 -(0.95 - x)TeO 2 were prepared using melt quenching technique. The results of ultrasonic velocities and elastic moduli showed that the addition of Nb 2 O 5 as a network modifier provides oxygen ions to change [TeO 4 ] tbps into [TeO 3 ] tps.

  4. Structural investigation and simulation of acoustic properties of some tellurite glasses using artificial intelligence technique

    Energy Technology Data Exchange (ETDEWEB)

    Gaafar, M.S., E-mail: mohamed_s_gaafar@hotmail.com [Ultrasonic Department, National Institute for Standards, Giza (Egypt); Physics Department, Faculty of Science, Majmaah University, Zulfi (Saudi Arabia); Abdeen, Mostafa A.M., E-mail: mostafa_a_m_abdeen@hotmail.com [Dept. of Eng. Math. and Physics, Faculty of Eng., Cairo University, Giza (Egypt); Marzouk, S.Y., E-mail: samir_marzouk2001@yahoo.com [Arab Academy of Science and Technology, Al-Horria, Heliopolis, Cairo (Egypt)

    2011-02-24

    Research highlights: > Simulation the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). > The glass network is strengthened by enhancing the linkage of Te-O chains. The tellurite network will also come to homogenization, because of uniform distribution of Nb{sup 5+} ions among the Te-O chains, though some of the tellurium-oxide polyhedra still link each other in edge sharing. > Excellent agreements between the measured values and the predicted values were obtained for over 50 different tellurite glass compositions. > The model we designed gives a better agreement as compared with Makishima and Machenzie model. - Abstract: The developments in the field of industry raise the need for simulating the acoustic properties of glass materials before melting raw material oxides. In this paper, we are trying to simulate the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). The artificial neural network (ANN) technique is introduced in the current study to simulate and predict important parameters such as density, longitudinal and shear ultrasonic velocities and elastic moduli (longitudinal and shear moduli). The ANN results were found to be in successful good agreement with those experimentally measured parameters. Then the presented ANN model is used to predict the acoustic properties of some new tellurite glasses. For this purpose, four glass systems xNb{sub 2}O{sub 5}-(1 - x)TeO{sub 2}, 0.1PbO-xNb{sub 2}O{sub 5}-(0.9 - x)TeO{sub 2}, 0.2PbO-xNb{sub 2}O{sub 5}-(0.8 - x)TeO{sub 2} and 0.05Bi{sub 2}O{sub 3}-xNb{sub 2}O{sub 5}-(0.95 - x)TeO{sub 2} were prepared using melt quenching technique. The results of ultrasonic velocities and elastic moduli showed that the addition of Nb{sub 2}O{sub 5} as a network modifier provides oxygen ions to change [TeO{sub 4}] tbps into [TeO{sub 3}] tps.

  5. Evaluating Acoustic Emission Signals as an in situ process monitoring technique for Selective Laser Melting (SLM)

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Karl A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Candy, Jim V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Guss, Gabe [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mathews, M. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-14

    In situ real-time monitoring of the Selective Laser Melting (SLM) process has significant implications for the AM community. The ability to adjust the SLM process parameters during a build (in real-time) can save time, money and eliminate expensive material waste. Having a feedback loop in the process would allow the system to potentially ‘fix’ problem regions before a next powder layer is added. In this study we have investigated acoustic emission (AE) phenomena generated during the SLM process, and evaluated the results in terms of a single process parameter, of an in situ process monitoring technique.

  6. Electromagnetically induced acoustic emission—novel NDT technique for damage evaluation

    Science.gov (United States)

    Finkel, P.; Godinez, V.; Miller, R.; Finlayson, R.

    2001-04-01

    A recently developed electromagnetically induced acoustic emission technique (EM AE) which can be used for damage assessment of thin walled conducting structures is described. This technique allows a structure to be loaded locally by applying an electromagnetic field in order to produce an AE response, which may be captured by conventional or fiber optic (FO) AE sensors. The advantage of this technique is that the localized dynamic stresses induced by a short current pulse in the presence of an external magnetic field aid in the detection of cracks. Also, it is shown that electromagnetic stimulation can be applied to enhance conventional ultrasonics by modulation of the scattered signal from the defect (EM UT). Experimental data is presented for the case of a fatigue crack near rivet holes in thin walled aluminum structures.

  7. Condition monitoring of a check valve for nuclear power plants by means of acoustic emission technique

    International Nuclear Information System (INIS)

    Lee, M. R.; Lee, J. H.; Kim, J. T.; Kim, J. S.; Luk, V. K.

    2003-01-01

    This work performed in support of the International Nuclear Energy Research Institute (INERI) program, which was to develop and demonstrate advanced sensor and computational technology for on-line monitoring of the condition of components, structures, and systems in advanced and next-generation nuclear power plants (NPPs). This primary object of this work is to investigate advanced condition monitoring systems based on acoustic emission detection that can provide timely detection of check valve degeneration and service aging so that maintenance/replacement could be preformed prior to loss safety function. The research is focused on the capability of AE technique to provide diagnostic information useful in determining check valve aging and degradation check valve failure and undesirable operating modes. This work also includes the investigation and adaptation of several advanced sensor technologies such as accelerometer and advanced ultrasonic technique. In addition, this work will develop advanced sophisticated signal processing, noise reduction, and pattern recognition techniques and algorithms from check valve degradation.

  8. Fatigue damage monitoring for basalt fiber reinforced polymer composites using acoustic emission technique

    Science.gov (United States)

    Wang, Wentao; Li, Hui; Qu, Zhi

    2012-04-01

    Basalt fiber reinforced polymer (BFRP) is a structural material with superior mechanical properties. In this study, unidirectional BFRP laminates with 14 layers are made with the hand lay-up method. Then, the acoustic emission technique (AE) combined with the scanning electronic microscope (SEM) technique is employed to monitor the fatigue damage evolution of the BFRP plates in the fatigue loading tests. Time-frequency analysis using the wavelet transform technique is proposed to analyze the received AE signal instead of the peak frequency method. A comparison between AE signals and SEM images indicates that the multi-frequency peaks picked from the time-frequency curves of AE signals reflect the accumulated fatigue damage evolution and fatigue damage patterns. Furthermore, seven damage patterns, that is, matrix cracking, delamination, fiber fracture and their combinations, are identified from the time-frequency curves of the AE signals.

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

    Science.gov (United States)

    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.

  10. New developments in NDT through electronic speckle pattern interferometry

    International Nuclear Information System (INIS)

    Mohan, S.; Murugesan, P; Mas, R.H.

    2007-01-01

    Full text: Optical holography and speckle interferometry are the emerging optical techniques that can be used for the measurements of microscopic parameters such as displacement, strain, stress and slope. These techniques are applied in various fields such as surface studies, non destructive testing, speckle metrology and steller interferometry. Even though many new NDT methods are available, the suitability for a specific application is based on the material property, nature of defects and sensitivity of detection. Difficulty in radiographic technique is that it fails in detecting tight cracks, planar defects and debonds. Microwave techniques has limited sensitivity for the defect detection and it is not suitable for the objects with metallic cases since the metals are perfect reflectors for the microwaves. Low modulus material attenuates the acoustic energy completely, making ultrasonic testing techniques not feasible. The recently evolved optoelectronic technique namely Electronic Speckle Pattern interferometry (ESPI) is a fast developing optical technique widely used for measuring displacement components, their derivatives, surface roughness, surface contours, shape and others. Due to non contact nature and high sensitivity, this technique has been used as a powerful on line inspection tool for non destructive pattern of materials in industrial environment. The salient feature of ESPI is its capability to display the correlation fringes in a real time on a monitor without the need of photographic processing or optical filtering. ESPI is an alternate non destructive technique suitable for propellant grains and other low modulus materials used in space vehicle systems. The optoelectronic technique can be used to detect cracks, voids and residual stresses etc.., in the components in the industrial environment. In the present investigation, speckle non destructive testing has been carried out on some selected low modulus materials used in space vehicles. The

  11. A novel femtosecond-gated, high-resolution, frequency-shifted shearing interferometry technique for probing pre-plasma expansion in ultra-intense laser experiments

    Energy Technology Data Exchange (ETDEWEB)

    Feister, S., E-mail: feister.7@osu.edu; Orban, C. [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Innovative Scientific Solutions, Inc., Dayton, Ohio 45459 (United States); Nees, J. A. [Innovative Scientific Solutions, Inc., Dayton, Ohio 45459 (United States); Center for Ultra-Fast Optical Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Morrison, J. T. [Fellow, National Research Council, Washington, D.C. 20001 (United States); Frische, K. D. [Innovative Scientific Solutions, Inc., Dayton, Ohio 45459 (United States); Chowdhury, E. A. [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Intense Energy Solutions, LLC., Plain City, Ohio 43064 (United States); Roquemore, W. M. [Air Force Research Laboratory, Dayton, Ohio 45433 (United States)

    2014-11-15

    Ultra-intense laser-matter interaction experiments (>10{sup 18} W/cm{sup 2}) with dense targets are highly sensitive to the effect of laser “noise” (in the form of pre-pulses) preceding the main ultra-intense pulse. These system-dependent pre-pulses in the nanosecond and/or picosecond regimes are often intense enough to modify the target significantly by ionizing and forming a plasma layer in front of the target before the arrival of the main pulse. Time resolved interferometry offers a robust way to characterize the expanding plasma during this period. We have developed a novel pump-probe interferometry system for an ultra-intense laser experiment that uses two short-pulse amplifiers synchronized by one ultra-fast seed oscillator to achieve 40-fs time resolution over hundreds of nanoseconds, using a variable delay line and other techniques. The first of these amplifiers acts as the pump and delivers maximal energy to the interaction region. The second amplifier is frequency shifted and then frequency doubled to generate the femtosecond probe pulse. After passing through the laser-target interaction region, the probe pulse is split and recombined in a laterally sheared Michelson interferometer. Importantly, the frequency shift in the probe allows strong plasma self-emission at the second harmonic of the pump to be filtered out, allowing plasma expansion near the critical surface and elsewhere to be clearly visible in the interferograms. To aid in the reconstruction of phase dependent imagery from fringe shifts, three separate 120° phase-shifted (temporally sheared) interferograms are acquired for each probe delay. Three-phase reconstructions of the electron densities are then inferred by Abel inversion. This interferometric system delivers precise measurements of pre-plasma expansion that can identify the condition of the target at the moment that the ultra-intense pulse arrives. Such measurements are indispensable for correlating laser pre-pulse measurements

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

    Science.gov (United States)

    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. Copyright 2009 Elsevier Ltd. All rights reserved.

  13. Detection of cavitation inception by acoustic technique in centrifugal pumps for nuclear application

    International Nuclear Information System (INIS)

    Prakash, V.; Prabhakar, R.; Rao, A.S.L.K.; Kale, R.D.

    1994-01-01

    The primary centrifugal pumps in a pool type reactor like the proposed Prototype Fast Breeder Reactor (PFBR) are required to operate at low values of available net positive suction head due to the limited submergence available in the pool. Pump hydraulics are designed to ensure that there is no cavitation or only minimum cavitation in the pump impeller in order to minimise long term erosion damage. Rigorous cavitation tests are usually carried out during development and final testing phase and a promising cavitation detection technique lies in acoustic noise measurements on the pump. As part of PFBR pump development programme, cavitation noise measurements were initially carried out on an experimental sodium pump in a water rig to establish detection procedures. Recently cavitation noise measurements were carried out on a 1/3 scale model impeller of PFBR pump along with visual observation of impeller passages to establish a correlation between visual and acoustic technique. Accelerometer responding to structure borne noise seems to give the best result. (author). 4 refs., 6 figs

  14. Preliminary studies for monitoring erosion in pipelines by the acoustic emission technique

    Energy Technology Data Exchange (ETDEWEB)

    Tiboni, G.B. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-graduacao em Engenharia Mecanica e de Materiais; Marquardt, T.A.S; SantaMaria, V.A.R.; Silva, C.H. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)

    2009-07-01

    The aim of this work is to present some applications of Acoustic Emission (AE), which is a powerful technique for nondestructive testing in Tribology, treated here as tests of friction, wear by contact fatigue, wear by slip and wear by erosion. In this work a special attention is given to solid particle erosion and hydro-abrasive erosion, problems found in almost every pipeline that lead to local loss of material and eventually rupture of the line. The technique of AE can be used as an efficient online tool when, primarily, to monitor tribological aspects such as the rate of wear of materials, as well as detect the spread of flaws in them. In wear by erosion, specifically, the parameters of RMS and acoustic energy are capable of correlation with the type of mechanism for removal of material. As a preliminary goal, erosive tests were performed with gas (air) without erosive particles, monitored by AE, varying the surface of the samples and the internal diameter the nozzle, taking the differences in signs of AE. Correlation between parameters of RMS and amplitude were noticed with the variables of the tests, such as roughness and fluid velocity. The RMS parameter showed a exponential correction with the fluid velocity, however the amplitude signals had a linear behavior. The knowledge of these parameters is essential for the development of a system that is able to quantify the wear rate of a pipeline without taking it out of operation. (author)

  15. Time-Delay Interferometry

    Directory of Open Access Journals (Sweden)

    Massimo Tinto

    2014-08-01

    Full Text Available Equal-arm detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is differenced at the photo detector. In this situation, much lower level secondary noises then set the overall performance. If, however, the two arms have different lengths (as will necessarily be the case with space-borne interferometers, the laser noise experiences different delays in the two arms and will hence not directly cancel at the detector. In order to solve this problem, a technique involving heterodyne interferometry with unequal arm lengths and independent phase-difference readouts has been proposed. It relies on properly time-shifting and linearly combining independent Doppler measurements, and for this reason it has been called time-delay interferometry (TDI. This article provides an overview of the theory, mathematical foundations, and experimental aspects associated with the implementation of TDI. Although emphasis on the application of TDI to the Laser Interferometer Space Antenna (LISA mission appears throughout this article, TDI can be incorporated into the design of any future space-based mission aiming to search for gravitational waves via interferometric measurements. We have purposely left out all theoretical aspects that data analysts will need to account for when analyzing the TDI data combinations.

  16. Generalized interferometry - I: theory for interstation correlations

    Science.gov (United States)

    Fichtner, Andreas; Stehly, Laurent; Ermert, Laura; Boehm, Christian

    2017-02-01

    We develop a general theory for interferometry by correlation that (i) properly accounts for heterogeneously distributed sources of continuous or transient nature, (ii) fully incorporates any type of linear and nonlinear processing, such as one-bit normalization, spectral whitening and phase-weighted stacking, (iii) operates for any type of medium, including 3-D elastic, heterogeneous and attenuating media, (iv) enables the exploitation of complete correlation waveforms, including seemingly unphysical arrivals, and (v) unifies the earthquake-based two-station method and ambient noise correlations. Our central theme is not to equate interferometry with Green function retrieval, and to extract information directly from processed interstation correlations, regardless of their relation to the Green function. We demonstrate that processing transforms the actual wavefield sources and actual wave propagation physics into effective sources and effective wave propagation. This transformation is uniquely determined by the processing applied to the observed data, and can be easily computed. The effective forward model, that links effective sources and propagation to synthetic interstation correlations, may not be perfect. A forward modelling error, induced by processing, describes the extent to which processed correlations can actually be interpreted as proper correlations, that is, as resulting from some effective source and some effective wave propagation. The magnitude of the forward modelling error is controlled by the processing scheme and the temporal variability of the sources. Applying adjoint techniques to the effective forward model, we derive finite-frequency Fréchet kernels for the sources of the wavefield and Earth structure, that should be inverted jointly. The structure kernels depend on the sources of the wavefield and the processing scheme applied to the raw data. Therefore, both must be taken into account correctly in order to make accurate inferences on

  17. Optical design and analysis of carbon dioxide laser fusion systems using interferometry and fast Fourier transform techniques

    International Nuclear Information System (INIS)

    Viswanathan, V.K.

    1979-01-01

    The optical design and analysis of the LASL carbon dioxide laser fusion systems required the use of techniques that are quite different from the currently used method in conventional optical design problems. The necessity for this is explored and the method that has been successfully used at Los Alamos to understand these systems is discussed with examples. This method involves characterization of the various optical components in their mounts by a Zernike polynomial set and using fast Fourier transform techniques to propagate the beam, taking diffraction and other nonlinear effects that occur in these types of systems into account. The various programs used for analysis are briefly discussed

  18. Experimental analysis of crack evolution in concrete by the acoustic emission technique

    Directory of Open Access Journals (Sweden)

    J. Saliba

    2015-10-01

    Full Text Available The fracture process zone (FPZ was investigated on unnotched and notched beams with different notch depths. Three point bending tests were realized on plain concrete under crack mouth opening displacement (CMOD control. Crack growth was monitored by applying the acoustic emission (AE technique. In order to improve our understanding of the FPZ, the width and length of the FPZ were followed based on the AE source locations maps and several AE parameters were studied during the entire loading process. The bvalue analysis, defined as the log-linear slope of the frequency-magnitude distribution of acoustic emissions, was also carried out to describe quantitatively the influence of the relative notch depth on the fracture process. The results show that the number of AE hits increased with the decrease of the relative notch depth and an important AE energy dissipation was observed at the crack initiation in unnotched beams. In addition, the relative notch depth influenced the AE characteristics, the process of crack propagation, and the brittleness of concrete.

  19. Sediment Types Determination Using Acoustic Techniques in the Northeastern Gulf of Mexico

    National Research Council Canada - National Science Library

    Kim, Gil

    2004-01-01

    ... those (acoustic impedance and grain size) in the northeastern Gulf of Mexico. The acoustic data were acquired using a 11 kHz normal incident echo sounder over approximately 2000 km of track line...

  20. Autoregressive techniques for acoustic detection of in-sodium water leaks

    International Nuclear Information System (INIS)

    Hayashi, K.

    1997-01-01

    We have been applied a background signal whitening filter built by univariate autoregressive model to the estimation problem of the leak start time and duration. In the 1995 present benchmark stage, we evaluated the method using acoustic signals from real hydrogen or water/steam injection experiments. The results show that the signal processing technique using this filter can detect reliability the leak signals with a sufficient signal-to-noise ratio. Even if the sensor signal contains non-boiling or non-leak high-amplitude pulses, they can be classified by spectral information. Especially, the feature signal made from the time-frequency spectrum of the filtered signal is very sensitive and useful. (author). 8 refs, 14 figs, 6 tabs

  1. An acoustic technique for the determination of liquor level in tanks

    International Nuclear Information System (INIS)

    Watson, J.; Jones, T.L.

    1980-02-01

    The design, development and application of a prototype suitable for the measurement of liquor levels in tanks is described. The technique involves directing an acoustic pulse down a constraining tube to the liquor surface and measuring the time of return of the reflected pulse. Using the equipment it is possible to determine the position of a solid surface with a total error of less than 1 mm. The prototype instrument was used to measure the volume of liquors contained in rectangular slab tanks used for accountancy purposes at Dounreay Nuclear Power Development Establishment. The total error obtained in an individual measurement of volume was less than 0.2 litres (95% confidence limits). The instrument may be used as a replacement for a Pneumercator system in existing installations. (author)

  2. Acoustic emission technique for leak detection in an end shield of a pressurized heavy water reactor

    International Nuclear Information System (INIS)

    Kalyanasundaram, P.; Jayakumar, T.; Raj, B.

    1989-01-01

    This paper discusses the successful application of the Acoustic Emission Technique (AET) for detection and location of leak paths present on the inaccessible side of an end shield of a Pressurized Heavy Water Reactor (PHWR). The methodology was based on the fact that air and water leak AE signals have different characteristic features. Baseline data was generated from a sound end-shield of a PHWR for characterizing the background noise. A mock up end-shield system with saw cut leak paths was used to verify the validity of the methodology. It was found that air leak signals under pressurisation (as low as 3 psi) could be detected by frequency domain analysis. Signals due to air leaks from various locations of a defective end-shield were acquired and analysed. It was possible to detect and locate leak paths. Presence of detected leak paths were further confirmed by alternate test. (orig.)

  3. Acoustic Emission and Echo Signal Compensation Techniques Applied to an Ultrasonic Logging-While-Drilling Caliper.

    Science.gov (United States)

    Yao, Yongchao; Ju, Xiaodong; Lu, Junqiang; Men, Baiyong

    2017-06-10

    A logging-while-drilling (LWD) caliper is a tool used for the real-time measurement of a borehole diameter in oil drilling engineering. This study introduces the mechanical structure and working principle of a new LWD caliper based on ultrasonic distance measurement (UDM). The detection range is a major performance index of a UDM system. This index is determined by the blind zone length and remote reflecting interface detection capability of the system. To reduce the blind zone length and detect near the reflecting interface, a full bridge acoustic emission technique based on bootstrap gate driver (BGD) and metal-oxide-semiconductor field effect transistor (MOSFET) is designed by analyzing the working principle and impedance characteristics of a given piezoelectric transducer. To detect the remote reflecting interface and reduce the dynamic range of the received echo signals, the relationships between the echo amplitude and propagation distance of ultrasonic waves are determined. A signal compensation technique based on time-varying amplification theory, which can automatically change the gain according to the echo arrival time is designed. Lastly, the aforementioned techniques and corresponding circuits are experimentally verified. Results show that the blind zone length in the UDM system of the LWD caliper is significantly reduced and the capability to detect the remote reflecting interface is considerably improved.

  4. Acoustic Emission and Echo Signal Compensation Techniques Applied to an Ultrasonic Logging-While-Drilling Caliper

    Directory of Open Access Journals (Sweden)

    Yongchao Yao

    2017-06-01

    Full Text Available A logging-while-drilling (LWD caliper is a tool used for the real-time measurement of a borehole diameter in oil drilling engineering. This study introduces the mechanical structure and working principle of a new LWD caliper based on ultrasonic distance measurement (UDM. The detection range is a major performance index of a UDM system. This index is determined by the blind zone length and remote reflecting interface detection capability of the system. To reduce the blind zone length and detect near the reflecting interface, a full bridge acoustic emission technique based on bootstrap gate driver (BGD and metal-oxide-semiconductor field effect transistor (MOSFET is designed by analyzing the working principle and impedance characteristics of a given piezoelectric transducer. To detect the remote reflecting interface and reduce the dynamic range of the received echo signals, the relationships between the echo amplitude and propagation distance of ultrasonic waves are determined. A signal compensation technique based on time-varying amplification theory, which can automatically change the gain according to the echo arrival time is designed. Lastly, the aforementioned techniques and corresponding circuits are experimentally verified. Results show that the blind zone length in the UDM system of the LWD caliper is significantly reduced and the capability to detect the remote reflecting interface is considerably improved.

  5. Condition monitoring of a check valve for nuclear power plants by means of acoustic emission technique

    International Nuclear Information System (INIS)

    Lee, Min Rae; Leee, Jun Hyun; Kim, Jung Tack; Kim, Jung Soo; Luk, V. K.

    2003-01-01

    This work performed in support of the International Nuclear Energy Research Initiative(INERI) program, which was to develop and demonstrate advanced sensor and computational technology for on-line monitoring of the condition of components, structures, and systems in advanced and next-generation nuclear power plants (NPPs). The primary object of this work is to investigate advanced condition monitoring systems based on acoustic emission detection that can provide timely detection of check valve degradation and service aging so that maintenance/replacement could be preformed prior to loss of safety function. The research is focused on the capability of AE technique to provide diagnostic information useful in determining check valve aging and degradation, check valve failures and undesirable operating modes. This work also includes the investigation and adaptation of several advanced sensor technologies such as accelerometer and advanced ultrasonic technique. In addition, this work will develop advanced sophisticated signal processing, noise reduction, and pattern recognition techniques and algorithms from check valve degradation.

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

    International Nuclear Information System (INIS)

    Payne, Allison; Bever, Josh de; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-01-01

    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

  7. Investigation of the Qadimah Fault in Western Saudi Arabia using Satellite Radar Interferometry and Geomorphology Analysis Techniques

    KAUST Repository

    Smith, Robert

    2012-07-01

    The Qadimah Fault has been mapped as a normal fault running through the middle of a planned $50 billion city. For this reason, there is an urgent need to evaluate the seismic hazard that the fault poses to the new development. Although several geophysical studies have supported the existence of a fault, the driving mechanism remains unclear. While a fault controlled by gravity gliding of the overburden on a mobile salt layer is unlikely to be of concern to the city, one caused by the continued extension of a normal rotational fault due to Red Sea rifting could result in a major earthquake. A number of geomorphology and geodetic techniques were used to better understand the fault. An analysis of topographic data revealed a sharp discontinuity in slope aspect and hanging wall tilting which strongly supports the existence of a normal fault. A GPS survey of an emergent reef platform which revealed a tilted coral surface also indicates that deformation has occurred in the region. An interferometric synthetic aperture radar investigation has also been performed to establish whether active deformation is occurring on the fault. Ground movements that could be consistent with inter-seismic strain accumulation have been observed, although the analysis is restricted by the limited data available. However, a simple fault model suggests that the deformation is unlikely due to continued crustal stretching. This, in addition to the lack of footwall uplift in the topography data, suggests that the fault is more likely controlled by a shallow salt layer. However, more work will need to be done in the future to confirm these findings.

  8. THE PULSATION OF χ CYGNI IMAGED BY OPTICAL INTERFEROMETRY: A NOVEL TECHNIQUE TO DERIVE DISTANCE AND MASS OF MIRA STARS

    International Nuclear Information System (INIS)

    Lacour, S.; Perrin, G.; Haubois, X.; Poncelet, A.; Thiebaut, E.; Meimon, S.; Pedretti, E.; Ridgway, S. T.; Monnier, J. D.; Berger, J. P.; Schuller, P. A.; Woodruff, H.; Le Coroller, H.; Millan-Gabet, R.; Lacasse, M.; Traub, W.

    2009-01-01

    We present infrared interferometric imaging of the S-type Mira star χ Cygni. The object was observed at four different epochs in 2005-2006 with the Infrared-Optical Telescope Array optical interferometer (H band). Images show up to 40% variation in the stellar diameter, as well as significant changes in the limb darkening and stellar inhomogeneities. Model fitting gave precise time-dependent values of the stellar diameter, and reveals presence and displacement of a warm molecular layer. The star radius, corrected for limb darkening, has a mean value of 12.1 mas and shows a 5.1 mas amplitude pulsation. Minimum diameter was observed at phase 0.94 ± 0.01. Maximum temperature was observed several days later at phase 1.02 ± 0.02. We also show that combining the angular acceleration of the molecular layer with CO (Δv = 3) radial velocity measurements yields a 5.9 ± 1.5 mas parallax. The constant acceleration of the CO molecules-during 80% of the pulsation cycle-lead us to argument for a free-falling layer. The acceleration is compatible with a gravitational field produced by a 2.1 +1.5 -0.7 solar mass star. This last value is in agreement with fundamental mode pulsator models. We foresee increased development of techniques consisting in combining radial velocity with interferometric angular measurements, ultimately allowing total mapping of the speed, density, and position of the diverse species in pulsation-driven atmospheres.

  9. LARA. Localization of an automatized refueling machine by acoustical sounding in breeder reactors - implementation of artificial intelligence techniques

    International Nuclear Information System (INIS)

    Lhuillier, C.; Malvache, P.

    1987-01-01

    The automatic control of the machine which handles the nuclear subassemblies in fast neutron reactors requires autonomous perception and decision tools. An acoustical device allows the machine to position in the work area. Artificial intelligence techniques are implemented to interpret the data: pattern recognition, scene analysis. The localization process is managed by an expert system. 6 refs.; 8 figs

  10. Coastal city subsidence in Shenzhen (China), monitored using multi-frequency radar interferometry time-series techniques

    Science.gov (United States)

    Liu, Peng; Li, Yongsheng; Singleton, Andrew; Li, Qingquan; Zhang, Jingfa; Li, Zhenhong

    2014-05-01

    In just 26 years, the coastal city of Shenzhen (Southern China) has been transformed from a small fishing village to a modern city with a population exceeding 8.5 million people. Following its designation as a Special Economic Zone in the 1980s, the city became a test bed for China's economic reforms and currently leads many new practices in urban planning. The rapid economic development was matched by a sharp increase in the demand for usable land and consequently, extensive coastal reclamation has been undertaken by piling rock fragments from nearby hills onto the seabed. However, it has recently been reported that new apartments, offices and transport networks built on the reclaimed land have become unusable due to ground subsidence. The additional threat of coastal inundation from sea-level rise also requires serious consideration. InSAR time-series techniques (such as Persistent Scatterer and Small Baseline InSAR) are capable of detecting sub-centimetre elevation changes of the Earth's surface over large areas and at a density far exceeding the capabilities of a GPS network - particularly for such an urban environment as Shenzhen. This study uses numerous independent tracks of SAR data (two ENVISAT C-band tracks and two ALOS L-band tracks) to determine the surface movements between 2004 and 2013. Quantitative comparative analyses are carried out in the overlapping area between two adjacent tracks, and thus no ground data is required to validate InSAR results. The results show greatest subsidence in coastal areas with the areas of reclaimed land also predominantly undergoing subsidence. The combination of different ascending and descending tracks allows 2D velocity fields to be estimated and it will be important to determine whether the subsidence from the recently reclaimed land is consolidation or part of a longer-term trend. This ability to provide accurate measurements of ground stability for the city of Shenzhen will help focus investigations into areas of

  11. Detecting Faults in Southern California using Computer-Vision Techniques and Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) Interferometry

    Science.gov (United States)

    Barba, M.; Rains, C.; von Dassow, W.; Parker, J. W.; Glasscoe, M. T.

    2013-12-01

    Knowing the location and behavior of active faults is essential for earthquake hazard assessment and disaster response. In Interferometric Synthetic Aperture Radar (InSAR) images, faults are revealed as linear discontinuities. Currently, interferograms are manually inspected to locate faults. During the summer of 2013, the NASA-JPL DEVELOP California Disasters team contributed to the development of a method to expedite fault detection in California using remote-sensing technology. The team utilized InSAR images created from polarimetric L-band data from NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) project. A computer-vision technique known as 'edge-detection' was used to automate the fault-identification process. We tested and refined an edge-detection algorithm under development through NASA's Earthquake Data Enhanced Cyber-Infrastructure for Disaster Evaluation and Response (E-DECIDER) project. To optimize the algorithm we used both UAVSAR interferograms and synthetic interferograms generated through Disloc, a web-based modeling program available through NASA's QuakeSim project. The edge-detection algorithm detected seismic, aseismic, and co-seismic slip along faults that were identified and compared with databases of known fault systems. Our optimization process was the first step toward integration of the edge-detection code into E-DECIDER to provide decision support for earthquake preparation and disaster management. E-DECIDER partners that will use the edge-detection code include the California Earthquake Clearinghouse and the US Department of Homeland Security through delivery of products using the Unified Incident Command and Decision Support (UICDS) service. Through these partnerships, researchers, earthquake disaster response teams, and policy-makers will be able to use this new methodology to examine the details of ground and fault motions for moderate to large earthquakes. Following an earthquake, the newly discovered faults can

  12. The application of the acoustic emission technique to stone decay by sodium sulphate in laboratory tests

    Directory of Open Access Journals (Sweden)

    Grossi, C. M.

    1997-03-01

    Full Text Available Acoustic emission was monitored during salt crystallisation cycles in order to study the mechanisms of rock deterioration by sodium sulphate in laboratory tests. Some porous carbonate stones used in Spanish monuments (Cathedral of Oviedo, Murcia and Seo Vella of Lérida were selected for this study. The acoustic emission detected during the different stages of the cycles (immersion, drying and cooling was interpreted to be the result of the salt behaviour inside the stone. The use of this technique has confirmed that this behaviour depends on salt characteristics (solubility, hydration state and polymorphism of anhydrous sodium sulphate and stone porosity and pore network.

    Para determinar los mecanismos de deterioro de las rocas debidos a la acción del sulfato de sodio, se ha registrado la emisión acústica durante ensayos de cristalización de sales en el laboratorio. Para ello, se han seleccionado tres piedras porosas carbonatadas utilizadas como materiales de construcción en monumentos españoles (Catedrales de Oviedo, Murcia y Seo Vella de Lérida. La emisión acústica detectada durante las diferentes etapas de los ciclos (inmersión, secado y enfriamiento se ha interpretado como debida al comportamiento de la sal en el interior de la piedra. Mediante esta técnica se ha confirmado que este comportamiento depende de las características de la sal (solubilidad, diferentes estados de hidratación y el polimorfismo del sulfato de sodio anhidro y de la porosidad y configuración del sistema poroso de las rocas.

  13. Diagnostics of glass fiber reinforced polymers and comparative analysis of their fabrication techniques with the use of acoustic emission

    Science.gov (United States)

    Bashkov, O. V.; Bryansky, A. A.; Panin, S. V.; Zaikov, V. I.

    2016-11-01

    Strength properties of the glass fiber reinforced polymers (GFRP) fabricated by vacuum and vacuum autoclave molding techniques were analyzed. Measurements of porosity of the GFRP parts manufactured by various molding techniques were conducted with the help of optical microscopy. On the basis of experimental data obtained by means of acoustic emission hardware/software setup, the technique for running diagnostics and forecasting the bearing capacity of polymeric composite materials based on the result of three-point bending tests has been developed. The operation principle of the technique is underlined by the evaluation of the power function index change which takes place on the dependence of the total acoustic emission counts versus the loading stress.

  14. Adaptive parametric model order reduction technique for optimization of vibro-acoustic models: Application to hearing aid design

    DEFF Research Database (Denmark)

    Creixell Mediante, Ester; Jensen, Jakob Søndergaard; Naets, Frank

    2018-01-01

    Finite Element (FE) models of complex structural-acoustic coupled systems can require a large number of degrees of freedom in order to capture their physical behaviour. This is the case in the hearing aid field, where acoustic-mechanical feedback paths are a key factor in the overall system...... by projecting the full system into a reduced space. A drawback of most of the existing techniques is that the vector basis of the reduced space is built at an offline phase where the full system must be solved for a large sample of parameter values, which can also become highly time consuming. In this work, we...

  15. Detection of steam leaks into sodium in fast reactor steam generators by acoustic techniques - An overview of Indian programme

    International Nuclear Information System (INIS)

    Prabhakar, R.; Vyjayanthi, R.K.; Kale, R.D.

    1990-01-01

    Realising the potential of acoustic leak detection technique, an experimental programme was initiated a few years back at Indira Gandhi Centre for Atomic Research (IGCAR) to develop this technique. The first phase of this programme consists of experiments to measure background noise characteristics on the steam generator modules of the 40 MW (thermal) Fast Breeder Test Reactor (FBTR) at Kalpakkam and experiments to establish leak noise characteristics with the help of a leak simulation set up. By subjecting the measured data from these experiments to signal analysis techniques, a criterion for acoustic leak detection for FBTR steam generator will be evolved. Second phase of this programme will be devoted to developing an acoustic leak detection system suitable for installation in the 500 MWe Prototype Fast Breeder Reactor (PFBR). This paper discusses the first phase of the experimental programme, results obtained from measurements carried out on FBTR steam generators and results obtained from leak simulation experiments. Acoustic leak detection system being considered for PFBR is also briefly described. 4 refs, 8 figs, 1 tab

  16. Flow visualization of acoustic levitation experiment

    Science.gov (United States)

    Baroth, ED

    1987-01-01

    Acoustic levitation experiments for space applications were performed. Holographic interferometry is being used to study the heat transfer rates on a heated rod enclosed in a 6 cu in chamber. Acoustic waves at levels up to 150 db increased the heating rates to the rod by factors of three to four. High speed real time holographic interferometry was used to measure the boundary layer on the heated rod. Data reduction and digitization of the interferograms are being implemented.

  17. Monitoring the viscosity of diesel engine lubricating oil by using acoustic emission technique, the selection of measurement parameters

    International Nuclear Information System (INIS)

    Othman Inayatullah; Nordin Jamaludin; Fauziah Mat

    2009-04-01

    Acoustic emission technique has been developed through years of monitoring and diagnosis of bearing, but it is still new in the diagnosis and monitoring of lubrication oil to bearings drive. The propagation of acoustic emission signal is generated when the signal piston on the cylinder liner lubricating oil which is a par. The signal is analyzed in time domain to obtain the parameters of root mean squared, amplitude, energy and courtesy. Lubricant viscosity will undergo changes due to temperature, pressure and useful. This study focuses on the appropriate parameters for the diagnosis and monitoring of lubricating oil viscosity. Studies were conducted at a constant rotational speed and temperature, but use a different age. The results showed that the energy parameter is the best parameter used in this monitoring. However, this parameter cannot be used directly and it should be analyzed using mathematical formulas. This mathematical formula is a relationship between acoustic emission energy with the viscosity of lubricating oil. (author)

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

    Science.gov (United States)

    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

  19. Acoustic waves in transversely excited atmospheric CO2 laser discharges: effect on performance and reduction techniques

    CSIR Research Space (South Africa)

    von Bergmann, HM

    2008-08-01

    Full Text Available Results are presented on the influence of acoustic waves on the performance of high-repetition-rate TEA CO2 lasers. It is shown that acoustic waves generated inside the laser cavity lead to nonuniform discharges, resulting in a deterioration...

  20. Source Identification in Structural Acoustics with an Inverse Frequency Response Function Technique

    NARCIS (Netherlands)

    Visser, Rene

    2002-01-01

    Inverse source identification based on acoustic measurements is essential for the investigation and understanding of sound fields generated by structural vibrations of various devices and machinery. Acoustic pressure measurements performed on a grid in the nearfield of a surface can be used to

  1. Acoustic cloaking and transformation acoustics

    International Nuclear Information System (INIS)

    Chen Huanyang; Chan, C T

    2010-01-01

    In this review, we give a brief introduction to the application of the new technique of transformation acoustics, which draws on a correspondence between coordinate transformation and material properties. The technique is formulated for both acoustic waves and linear liquid surface waves. Some interesting conceptual devices can be designed for manipulating acoustic waves. For example, we can design acoustic cloaks that make an object invisible to acoustic waves, and the cloak can either encompass or lie outside the object to be concealed. Transformation acoustics, as an analog of transformation optics, can go beyond invisibility cloaking. As an illustration for manipulating linear liquid surface waves, we show that a liquid wave rotator can be designed and fabricated to rotate the wave front. The acoustic transformation media require acoustic materials which are anisotropic and inhomogeneous. Such materials are difficult to find in nature. However, composite materials with embedded sub-wavelength resonators can in principle be made and such 'acoustic metamaterials' can exhibit nearly arbitrary values of effective density and modulus tensors to satisfy the demanding material requirements in transformation acoustics. We introduce resonant sonic materials and Helmholtz resonators as examples of acoustic metamaterials that exhibit resonant behaviour in effective density and effective modulus. (topical review)

  2. Holographic interferometry in construction analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hartikainen, T.

    1995-12-31

    In this work techniques for visualizing phase and opaque objects by ruby laser interferometry are introduced. A leakage flow as a phase object is studied by holographic interferometry and the intensity distribution of the interferograms presenting the leakage flow are computer-simulated. A qualitative and quantitative analysis of the leakage flow is made. The analysis is based on the experimental and theoretical results presented in this work. The holographic setup and the double pass method for visualizing leakage flow are explained. A vibrating iron plate is the opaque object. Transient impact waves are generated by a pistol bullet on the iron plate and visualized by holographic interferometry. An apparatus with the capability of detecting and calculating the delays necessary for laser triggering is introduced. A time series of interferograms presenting elastic wave formation in an iron plate is shown. A computer-simulation of the intensity distributions of these interferograms is made. An analysis based on the computer-simulation and the experimental data of the transient elastic wave is carried out and the results are presented. (author)

  3. Holographic interferometry of high pressure

    International Nuclear Information System (INIS)

    McIlwain, M.E.

    1987-01-01

    Measurements in turbulent flows have been historically performed using various types of probes and optical diagnostic methods. In general, probes suffer from plasma perturbation effects and are single point determination methods. Optical methods appear to be better suited to determinations in turbulent flows, however interpretation of the resulting data can often be complex. Methods such as laser Doppler anemometry, which relies on entrained particles, suffers from the fact that particles small enough to be swept along by the plasma are usually melted or sublimed in the plasma. Light refraction or diffraction methods such as shadow photography, interferometry, and holography have also been used to observe plasma flows. These methods typically suffer from the difficulty of interpreting line of sight images and obtaining quantitative data. A new method based on multi-pass holographic interferometry will be discussed. This method has certain advantages which can significantly simplify the complexity of line of sight interferometry image deconvolution. When the method employs high speed cinematography, time resolved images of the plasma flow can be obtained. This method has been applied to both transferred and non-transferred arcs and various types of DC-plasma torch produced jets. These studies and conclusions as to the usefulness of the technique are presented

  4. Optical interferometry in astronomy

    International Nuclear Information System (INIS)

    Monnier, John D

    2003-01-01

    Here I review the current state of the field of optical stellar interferometry, concentrating on ground-based work although a brief report of space interferometry missions is included. We pause both to reflect on decades of immense progress in the field as well as to prepare for a new generation of large interferometers just now being commissioned (most notably, the CHARA, Keck and VLT Interferometers). First, this review summarizes the basic principles behind stellar interferometry needed by the lay-physicist and general astronomer to understand the scientific potential as well as technical challenges of interferometry. Next, the basic design principles of practical interferometers are discussed, using the experience of past and existing facilities to illustrate important points. Here there is significant discussion of current trends in the field, including the new facilities under construction and advanced technologies being debuted. This decade has seen the influence of stellar interferometry extend beyond classical regimes of stellar diameters and binary orbits to new areas such as mapping the accretion discs around young stars, novel calibration of the cepheid period-luminosity relation, and imaging of stellar surfaces. The third section is devoted to the major scientific results from interferometry, grouped into natural categories reflecting these current developments. Lastly, I consider the future of interferometry, highlighting the kinds of new science promised by the interferometers coming on-line in the next few years. I also discuss the longer-term future of optical interferometry, including the prospects for space interferometry and the possibilities of large-scale ground-based projects. Critical technological developments are still needed to make these projects attractive and affordable

  5. Application of acoustic emission technique and friction welding for excavator hose nipple

    International Nuclear Information System (INIS)

    Kong, Yu Sik; Lee, Jin Kyung

    2013-01-01

    Friction welding is a very useful joining process to weld metals which have axially symmetric cross section. In this paper, the feasibility of industry application was determined by analyzing the mechanical properties of weld region for a specimen of tube-to-tube shape for excavator hose nipple with friction welding, and optimized welding variables were suggested. In order to accomplish this object, friction heating pressure and friction heating time were selected as the major process variables and the experiment was performed in three levels of each parameter. An acoustic emission(AE) technique was applied to evaluate the optimal friction welding conditions nondestructively. AE parameters of accumulative count and event were analyzed in terms of generating trend of AE signals across the full range of friction weld. The typical waveform and frequency spectrum of AE signals which is generated by friction weld were discussed. From this study the optimal welding variables could be suggested as rotating speed of 1300 rpm, friction heating pressure of 15 MPa, and friction heating time of 10 sec. AE event was a useful parameter to estimate the tensile strength of tube-to tube specimen with friction weld.

  6. A novel acoustic method for gas flow measurement using correlation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Knuuttila, M. [VTT Chemical Technology, Espoo (Finland). Industrial Physics

    1997-12-31

    The study demonstrates a new kind of acoustic method for gas flow measurement. The method uses upstream and downstream propagating low frequency plane wave and correlation techniques for volume flow rate determination. The theory of propagating low frequency plane waves in the pipe is introduced and is proved empirically to be applicable for flow measurement. The flow profile dependence of the method is verified and found to be negligible at least in the region of moderate perturbations. The physical principles of the method were applied in practice in the form of a flowmeter with new design concepts. The developed prototype meters were verified against the reference standard of NMI (Nederlands Meetinstituut), which showed that a wide dynamic range of 1:80 is achievable with total expanded uncertainty below 0.3 %. Also the requirements used for turbine meters of linearity, weighted mean error and stability were shown to be well fulfilled. A brief comparison with other flowmeter types shows the new flowmeter to be competitive. The advantages it offers are a small pressure drop over the meter, no blockage of flow in possible malfunction, no pulsation to flow, essentially no moving parts, and the possibility for bidirectional measurements. The introduced flowmeter is also capable of using the telephone network or a radio-modem to read the consumption of gas and report its operation to the user. (orig.) 51 refs.

  7. Acoustic analysis of swallowing sounds: a new technique for assessing dysphagia.

    Science.gov (United States)

    Santamato, Andrea; Panza, Francesco; Solfrizzi, Vincenzo; Russo, Anna; Frisardi, Vincenza; Megna, Marisa; Ranieri, Maurizio; Fiore, Pietro

    2009-07-01

    To perform acoustic analysis of swallowing sounds, using a microphone and a notebook computer system, in healthy subjects and patients with dysphagia affected by neurological diseases, testing the positive/negative predictive value of a pathological pattern of swallowing sounds for penetration/aspiration. Diagnostic test study, prospective, not blinded, with the penetration/aspiration evaluated by fibreoptic endoscopy of swallowing as criterion standard. Data from a previously recorded database of normal swallowing sounds for 60 healthy subjects according to gender, age, and bolus consistency was compared with those of 15 patients with dysphagia from a university hospital referral centre who were affected by various neurological diseases. Mean duration of the swallowing sounds and post-swallowing apnoea were recorded. Penetration/aspiration was verified by fibreoptic endoscopy of swallowing in all patients with dysphagia. The mean duration of swallowing sounds for a liquid bolus of 10 ml water was significantly different between patients with dysphagia and healthy patients. We also described patterns of swallowing sounds and tested the negative/positive predictive values of post-swallowing apnoea for penetration/aspiration verified by fibreoptic endoscopy of swallowing (sensitivity 0.67 (95% confidence interval 0.24-0.94); specificity 1.00 (95% confidence interval 0.56-1.00)). The proposed technique for recording and measuring swallowing sounds could be incorporated into the bedside evaluation, but it should not replace the use of more diagnostic and valuable measures.

  8. The coupling technique: A two-wave acoustic method for the study of dislocation dynamics

    Science.gov (United States)

    Gremaud, G.; Bujard, M.; Benoit, W.

    1987-03-01

    Progress in the study of dislocation dynamics has been achieved using a two-wave acoustic method, which has been called the coupling technique. In this method, the attenuation α and the velocity v of ultrasonic waves are measured in a sample submitted simultaneously to a harmonic stress σ of low frequency. Closed curves Δα(σ) and Δv/v(σ) are drawn during each cycle of the applied stress. The shapes of these curves and their evolution are characteristic of each dislocation motion mechanism which is activated by the low-frequency applied stress. For this reason, the closed curves Δα(σ) and Δv/v(σ) can be considered as signatures of the interaction mechanism which controls the low-frequency dislocation motion. In this paper, the concept of signature is presented and explained with some experimental examples. It will also be shown that theoretical models can be developed which explain very well the experimental results.

  9. Unusual structure in forsterite glass synthesized by an aero-acoustic levitation technique

    International Nuclear Information System (INIS)

    Kohara, Shinji; Suzuya, Kentaro; Takeuchi, Ken

    2005-01-01

    Forsterite Mg 2 SiO 4 exhibits an orthorhombic structure consisted of two kinds of MgO 6 octahedra. One of them forms edge-sharing ribbons along the [001] direction which are linked by the other kind of edge-sharing MgO 6 octahedra, resulting in a three-dimensional framework. Given only 33.3 mol% of SiO 2 in the material, the SiO 4 tetrahedra are isolated within the framework, sharing the O-O bonds with the common edges of the MgO 6 octahedra. If forsterite can be vitrified, an interesting question concerning the glass structure arises because there is insufficient glass forming SiO 2 to establish the corner-sharing SiO 4 tetrahedral net-work needed in conventional silicate glasses. A bulk Mg 2 SiO 4 glass was synthesized using an aero-acoustic levitation technique and to visualize the short-to intermediate-range structure by a combined high-energy synchrotron x-ray and neutron diffraction and reverse Monte Carlo computer simulation. We found that the role of network former is largely taken on by corner-and edge-sharing ionic magnesium species that adopt 4-, 5- and 6-coordination with oxygen. (author)

  10. Delamination of plasters applied to historical masonry walls: analysis by acoustic emission technique and numerical model

    Science.gov (United States)

    Grazzini, A.; Lacidogna, G.; Valente, S.; Accornero, F.

    2018-06-01

    Masonry walls of historical buildings are subject to rising damp effects due to capillary or rain infiltrations, which in the time produce decay and delamination of historical plasters. In the restoration of masonry buildings, the plaster detachment frequently occurs because of mechanical incompatibility in repair mortar. An innovative laboratory procedure is described for test mechanical adhesion of new repair mortars. Compression static tests were carried out on composite specimens stone block-repair mortar, which specific geometry can test the de-bonding process of mortar in adherence with a stone masonry structure. The acoustic emission (AE) technique was employed for estimating the amount of energy released from fracture propagation in adherence surface between mortar and stone. A numerical simulation was elaborated based on the cohesive crack model. The evolution of detachment process of mortar in a coupled stone brick-mortar system was analysed by triangulation of AE signals, which can improve the numerical model and predict the type of failure in the adhesion surface of repair plaster. Through the cohesive crack model, it was possible to interpret theoretically the de-bonding phenomena occurring at the interface between stone block and mortar. Therefore, the mechanical behaviour of the interface is characterized.

  11. Report on Non-invasive acoustic monitoring of D2O concentration Oct 31 2017

    Energy Technology Data Exchange (ETDEWEB)

    Pantea, Cristian [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sinha, Dipen N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lakis, Rollin Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Beedle, Christopher Craig [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Davis, Eric Sean [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-11-06

    There is an urgent need for real-time monitoring of the hydrogen /deuterium ratio (H/D) for heavy water production monitoring. Based upon published literature, sound speed is sensitive to the deuterium content of heavy water and can be measured using existing acoustic methods to determine the deuterium concentration in heavy water solutions. We plan to adapt existing non-invasive acoustic techniques (Swept-Frequency Acoustic Interferometry and Gaussian-pulse acoustic technique) for the purpose of quantifying H/D ratios in solution. A successful demonstration will provide an easily implemented, low cost, and non-invasive method for remote and unattended H/D ratio measurements with a resolution of less than 0.2% vol.

  12. Mechanical Strain Measurement from Coda Wave Interferometry

    Science.gov (United States)

    Azzola, J.; Schmittbuhl, J.; Zigone, D.; Masson, F.; Magnenet, V.

    2017-12-01

    Coda Wave Interferometry (CWI) aims at tracking small changes in solid materials like rocks where elastic waves are diffusing. They are intensively sampling the medium, making the technique much more sensitive than those relying on direct wave arrivals. Application of CWI to ambient seismic noise has found a large range of applications over the past years like for multiscale imaging but also for monitoring complex structures such as regional faults or reservoirs (Lehujeur et al., 2015). Physically, observed changes are typically interpreted as small variations of seismic velocities. However, this interpretation remains questionable. Here, a specific focus is put on the influence of the elastic deformation of the medium on CWI measurements. The goal of the present work is to show from a direct numerical and experimental modeling that deformation signal also exists in CWI measurements which might provide new outcomes for the technique.For this purpose, we model seismic wave propagation within a diffusive medium using a spectral element approach (SPECFEM2D) during an elastic deformation of the medium. The mechanical behavior is obtained from a finite element approach (Code ASTER) keeping the mesh grid of the sample constant during the whole procedure to limit numerical artifacts. The CWI of the late wave arrivals in the synthetic seismograms is performed using both a stretching technique in the time domain and a frequency cross-correlation method. Both show that the elastic deformation of the scatters is fully correlated with time shifts of the CWI differently from an acoustoelastic effect. As an illustration, the modeled sample is chosen as an effective medium aiming to mechanically and acoustically reproduce a typical granitic reservoir rock.Our numerical approach is compared to experimental results where multi-scattering of an acoustic wave through a perforated loaded Au4G (Dural) plate is performed at laboratory scale. Experimental and numerical results of the

  13. Study of the uniform corrosion of non alloy and stainless steels: combined utilization of acoustic emission and electrochemical techniques

    International Nuclear Information System (INIS)

    Jaubert, Lionel

    2004-01-01

    In chemical and petrochemical industry, uniform corrosion induces important economic and security disappointments. The mechanisms of this damaging corrosion mode are well understood, but methods for on-line detection are badly missing. Acoustic emission technique presents, to palliate this lack, potentialities that have been studied in an instrumented laboratory loop allowing the simulation of industrial uniform corrosion conditions. In acidic media, acoustic activity is related to the hydrogen evolution resulting from proton reduction; it is therefore well correlated to the damage severity. In neutral aerated media, the deposit formation of corrosion products is not very emissive. Yet, a specific study of frequency parameters allows detection of corrosion evolution, but in that case, the quantification of corrosion rate remains difficult. A subsidiary study confirms the technique applicability in the case of 'acidic' corrosion, even in very noisy conditions. (author) [fr

  14. Signal processing techniques for the acoustic detection of boiling in LMFBRs: preliminary results of an IAEA collaborative research programme

    International Nuclear Information System (INIS)

    Macleod, I.D.

    1988-01-01

    A specialist meeting organised by the International Working Group on Fast Reactors (IWGFR) of the International Atomic Energy Agency (IAEA) was held at Chester in the United Kingdom in 1981 to discuss techniques for the detection of acoustic noise from boiling. This meeting recommended that a benchmark test should be carried out to evaluate and compare signal processing methods for use in the detection of the acoustic noise produced by boiling sodium. In response to this recommendation the IAEA set up a collaborative research programme to examine and compare the processing techniques used in the laboratories of member countries. Eight laboratories in six countries have taken part in the programme which will be completed in 1988. This paper summarises the results obtained so far. (author)

  15. Application of acoustic techniques for exploration of submerged area in connection with hydro-projects

    Digital Repository Service at National Institute of Oceanography (India)

    Vora, K.H.

    route selection, developments of ports and harbours, etc. as also for post-constructional inspection like determination of exposed pipeline, or extent of siltation in reservoir. The acoustic methods use sound waves of different characteristics to obtain...

  16. Extreme ultraviolet interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, Kenneth A. [Univ. of California, Berkeley, CA (United States). Dept. of Physics

    1997-12-01

    EUV lithography is a promising and viable candidate for circuit fabrication with 0.1-micron critical dimension and smaller. In order to achieve diffraction-limited performance, all-reflective multilayer-coated lithographic imaging systems operating near 13-nm wavelength and 0.1 NA have system wavefront tolerances of 0.27 nm, or 0.02 waves RMS. Owing to the highly-sensitive resonant reflective properties of multilayer mirrors and extraordinarily tight tolerances set forth for their fabrication, EUV optical systems require at-wavelength EUV interferometry for final alignment and qualification. This dissertation discusses the development and successful implementation of high-accuracy EUV interferometric techniques. Proof-of-principle experiments with a prototype EUV point-diffraction interferometer for the measurement of Fresnel zoneplate lenses first demonstrated sub-wavelength EUV interferometric capability. These experiments spurred the development of the superior phase-shifting point-diffraction interferometer (PS/PDI), which has been implemented for the testing of an all-reflective lithographic-quality EUV optical system. Both systems rely on pinhole diffraction to produce spherical reference wavefronts in a common-path geometry. Extensive experiments demonstrate EUV wavefront-measuring precision beyond 0.02 waves RMS. EUV imaging experiments provide verification of the high-accuracy of the point-diffraction principle, and demonstrate the utility of the measurements in successfully predicting imaging performance. Complementary to the experimental research, several areas of theoretical investigation related to the novel PS/PDI system are presented. First-principles electromagnetic field simulations of pinhole diffraction are conducted to ascertain the upper limits of measurement accuracy and to guide selection of the pinhole diameter. Investigations of the relative merits of different PS/PDI configurations accompany a general study of the most significant sources

  17. Noncontacting acoustics-based temperature measurement techniques in rapid thermal processing

    Science.gov (United States)

    Lee, Yong J.; Chou, Ching-Hua; Khuri-Yakub, Butrus T.; Saraswat, Krishna C.

    1991-04-01

    Temperature measurement of silicon wafers based on the temperature dependence of acoustic waves is studied. The change in the temperature-dependent dispersion relations of the plate modes through the wafer can be exploited to provide a viable temperature monitoring scheme with advantages over both thermocouples and pyrometers. Velocity measurements of acoustic waves through a thin layer of ambient directly above the wafer provides the temperature of the wafer-ambient interface. 1.

  18. Comparison of Estimation Techniques for Vibro-Acoustic Transfer Path Analysis

    Directory of Open Access Journals (Sweden)

    Paulo Eduardo França Padilha

    2006-01-01

    Full Text Available Vibro-acoustic Transfer Path Analysis (TPA is a tool to evaluate the contribution of different energy propagation paths between a source and a receiver, linked to each other by a number of connections. TPA is typically used to quantify and rank the relative importance of these paths in a given frequency band, determining the most significant one to the receiver. Basically, two quantities have to be determined for TPA: the operational forces at each transfer path and the Frequency Response Functions (FRF of these paths. The FRF are obtained either experimentally or analytically, and the influence of the mechanical impedance of the source can be taken into account or not. The operational forces can be directly obtained from measurements using force transducers or indirectly estimated from auxiliary response measurements. Two methods to obtain the operational forces indirectly – the Complex Stiffness Method (CSM and the Matrix Inversion Method (MIM – associated with two possible configurations to determine the FRF – including and excluding the source impedance – are presented and discussed in this paper. The effect of weak and strong coupling among the paths is also commented considering the techniques previously presented. The main conclusion is that, with the source removed, CSM gives more accurate results. On the other hand, with the source present, MIM is preferable. In the latter case, CSM should be used only if there is a high impedance mismatch between the source and the receiver. Both methods are not affected by a higher or lower degree of coupling among the transfer paths.

  19. Global astrometry with the space interferometry mission

    Science.gov (United States)

    Boden, A.; Unwin, S.; Shao, M.

    1997-01-01

    The prospects for global astrometric measurements with the space interferometry mission (SIM) are discussed. The SIM mission will perform four microarcsec astrometric measurements on objects as faint as 20 mag using the optical interferometry technique with a 10 m baseline. The SIM satellite will perform narrow angle astrometry and global astrometry by means of an astrometric grid. The sensitivities of the SIM global astrometric performance and the grid accuracy versus instrumental parameters and sky coverage schemes are reported on. The problems in finding suitable astrometric grid objects to support microarcsec astrometry, and related ground-based observation programs are discussed.

  20. Monitoring civil infrastructure using satellite radar interferometry

    NARCIS (Netherlands)

    Chang, L.

    2015-01-01

    Satellite radar interferometry (InSAR) is a precise and efficient technique to monitor deformation on Earth with millimeter precision. Most InSAR applications focus on geophysical phenomena, such as earthquakes, volcanoes, or subsidence. Monitoring civil infrastructure with InSAR is relatively new,

  1. A system for airborne SAR interferometry

    DEFF Research Database (Denmark)

    Madsen, Søren Nørvang; Skou, Niels; Granholm, Johan

    1996-01-01

    Interferometric synthetic aperture radar (INSAR) systems have already demonstrated that elevation maps can be generated rapidly with single pass airborne across-track interferometry systems (XTT), and satellite repeat track interferometry (RTT) techniques have been used to map both elevation...... and perturbations of the surface of the Earth. The Danish Center for Remote Sensing (DCRS) has experimented with airborne INSAR since 1993. Multiple track data are collected in a special mode in which the radar directly steers the aircraft which allows for very precise control of the flight path. Such data sets......) the status of the airborne interferometry activities at DCRS, including the present system configuration, recent results, and some scientific applications of the system....

  2. On the use of a variational technique based on integral equations for plane acoustic and vibro-acoustic problems

    DEFF Research Database (Denmark)

    Brunskog, Jonas; Richard, Antoine Philippe André

    2016-01-01

    Problems such as sound insulation and absorption of plane structures in laboratory conditions can theoretically be described as an integral or integral-differential equation. This equation contains the Green’s function integrated over the surface, which describes the radiation from the surface....... A variational technique, well described by Morse and Ingard, has successfully been used for both absorption and sound insulation for a plane incident wave. The resulting formulas are surprisingly simple, accurate and robust. Moreover, they capture the physics of sound radiation of a finite surface well. However...

  3. Acoustic emission non-destructive testing of structures using source location techniques.

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Vibration impact acoustic emission technique for identification and analysis of defects in carbon steel tubes: Part A Statistical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Halim, Zakiah Abd [Universiti Teknikal Malaysia Melaka (Malaysia); Jamaludin, Nordin; Junaidi, Syarif [Faculty of Engineering and Built, Universiti Kebangsaan Malaysia, Bangi (Malaysia); Yahya, Syed Yusainee Syed [Universiti Teknologi MARA, Shah Alam (Malaysia)

    2015-04-15

    Current steel tubes inspection techniques are invasive, and the interpretation and evaluation of inspection results are manually done by skilled personnel. This paper presents a statistical analysis of high frequency stress wave signals captured from a newly developed noninvasive, non-destructive tube inspection technique known as the vibration impact acoustic emission (VIAE) technique. Acoustic emission (AE) signals have been introduced into the ASTM A179 seamless steel tubes using an impact hammer, and the AE wave propagation was captured using an AE sensor. Specifically, a healthy steel tube as the reference tube and four steel tubes with through-hole artificial defect at different locations were used in this study. The AE features extracted from the captured signals are rise time, peak amplitude, duration and count. The VIAE technique also analysed the AE signals using statistical features such as root mean square (r.m.s.), energy, and crest factor. It was evident that duration, count, r.m.s., energy and crest factor could be used to automatically identify the presence of defect in carbon steel tubes using AE signals captured using the non-invasive VIAE technique.

  5. ACOUSTIC TECHNIQUES FOR THE MAPPING OF THE DISTRIBUTION OF CONTAMINATED SEDIMENTS

    Science.gov (United States)

    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...

  6. A Multi-Model Reduction Technique for Optimization of Coupled Structural-Acoustic Problems

    DEFF Research Database (Denmark)

    Creixell Mediante, Ester; Jensen, Jakob Søndergaard; Brunskog, Jonas

    2016-01-01

    Finite Element models of structural-acoustic coupled systems can become very large for complex structures with multiple connected parts. Optimization of the performance of the structure based on harmonic analysis of the system requires solving the coupled problem iteratively and for several frequ....... Several methods are compared in terms of accuracy and size of the reduced systems for optimization of simple models....

  7. Comparing Laser Interferometry and Atom Interferometry Approaches to Space-Based Gravitational-Wave Measurement

    Science.gov (United States)

    Baker, John; Thorpe, Ira

    2012-01-01

    Thoroughly studied classic space-based gravitational-wave missions concepts such as the Laser Interferometer Space Antenna (LISA) are based on laser-interferometry techniques. Ongoing developments in atom-interferometry techniques have spurred recently proposed alternative mission concepts. These different approaches can be understood on a common footing. We present an comparative analysis of how each type of instrument responds to some of the noise sources which may limiting gravitational-wave mission concepts. Sensitivity to laser frequency instability is essentially the same for either approach. Spacecraft acceleration reference stability sensitivities are different, allowing smaller spacecraft separations in the atom interferometry approach, but acceleration noise requirements are nonetheless similar. Each approach has distinct additional measurement noise issues.

  8. Study on flow-induced acoustic resonance in symmetrically located side-branches using dynamic PIV technique

    International Nuclear Information System (INIS)

    Li, Yanrong; Inagaki, Terumi; Nishi, Yasuyuki; Someya, Satoshi; Okamoto, Koji

    2014-01-01

    Flow-induced acoustic resonance in a piping system containing closed coaxial side-branches was investigated experimentally. Resonance characteristics of the piping system were examined by a microphone. The results revealed that the resonance frequencies of the shear layer instability were locked in corresponding to the natural frequencies of the side-branches. Phase-averaged velocity fields were obtained two-dimensionally in the junction of coaxial side-branches by dynamic particle image velocimetry (PIV), while the acoustic resonance was induced at the first and second hydrodynamic modes. Patterns of jet correspond to two hydrodynamic modes were derived from the phase-averaged velocity fields. The dynamic PIV can acquire time-series velocity fluctuations, then, two-dimensional phase delay maps under resonance and off-resonance conditions in the junction of coaxial side-branches were obtained. Experimental results show that the proposed phase delay map method costs less experiment and computation time and achieves a better accuracy and repetition than the phase-locking technique. In addition, the phase delay map method can obtain phase difference under the different frequency components. This is important when two different acoustic modes were induced in one experimental condition. (author)

  9. Battlefield acoustics

    CERN Document Server

    Damarla, Thyagaraju

    2015-01-01

    This book presents all aspects of situational awareness in a battlefield using acoustic signals. It starts by presenting the science behind understanding and interpretation of sound signals. The book then goes on to provide various signal processing techniques used in acoustics to find the direction of sound source, localize gunfire, track vehicles, and detect people. The necessary mathematical background and various classification and fusion techniques are presented. The book contains majority of the things one would need to process acoustic signals for all aspects of situational awareness in one location. The book also presents array theory, which is pivotal in finding the direction of arrival of acoustic signals. In addition, the book presents techniques to fuse the information from multiple homogeneous/heterogeneous sensors for better detection. MATLAB code is provided for majority of the real application, which is a valuable resource in not only understanding the theory but readers, can also use the code...

  10. Vibration impact acoustic emission technique for identification and analysis of defects in carbon steel tubes: Part B Cluster analysis

    Energy Technology Data Exchange (ETDEWEB)

    Halim, Zakiah Abd [Universiti Teknikal Malaysia Melaka (Malaysia); Jamaludin, Nordin; Junaidi, Syarif [Faculty of Engineering and Built, Universiti Kebangsaan Malaysia, Bangi (Malaysia); Yahya, Syed Yusainee Syed [Universiti Teknologi MARA, Shah Alam (Malaysia)

    2015-04-15

    Current steel tubes inspection techniques are invasive, and the interpretation and evaluation of inspection results are manually done by skilled personnel. Part A of this work details the methodology involved in the newly developed non-invasive, non-destructive tube inspection technique based on the integration of vibration impact (VI) and acoustic emission (AE) systems known as the vibration impact acoustic emission (VIAE) technique. AE signals have been introduced into a series of ASTM A179 seamless steel tubes using the impact hammer. Specifically, a good steel tube as the reference tube and four steel tubes with through-hole artificial defect at different locations were used in this study. The AEs propagation was captured using a high frequency sensor of AE systems. The present study explores the cluster analysis approach based on autoregressive (AR) coefficients to automatically interpret the AE signals. The results from the cluster analysis were graphically illustrated using a dendrogram that demonstrated the arrangement of the natural clusters of AE signals. The AR algorithm appears to be the more effective method in classifying the AE signals into natural groups. This approach has successfully classified AE signals for quick and confident interpretation of defects in carbon steel tubes.

  11. Vibration impact acoustic emission technique for identification and analysis of defects in carbon steel tubes: Part B Cluster analysis

    International Nuclear Information System (INIS)

    Halim, Zakiah Abd; Jamaludin, Nordin; Junaidi, Syarif; Yahya, Syed Yusainee Syed

    2015-01-01

    Current steel tubes inspection techniques are invasive, and the interpretation and evaluation of inspection results are manually done by skilled personnel. Part A of this work details the methodology involved in the newly developed non-invasive, non-destructive tube inspection technique based on the integration of vibration impact (VI) and acoustic emission (AE) systems known as the vibration impact acoustic emission (VIAE) technique. AE signals have been introduced into a series of ASTM A179 seamless steel tubes using the impact hammer. Specifically, a good steel tube as the reference tube and four steel tubes with through-hole artificial defect at different locations were used in this study. The AEs propagation was captured using a high frequency sensor of AE systems. The present study explores the cluster analysis approach based on autoregressive (AR) coefficients to automatically interpret the AE signals. The results from the cluster analysis were graphically illustrated using a dendrogram that demonstrated the arrangement of the natural clusters of AE signals. The AR algorithm appears to be the more effective method in classifying the AE signals into natural groups. This approach has successfully classified AE signals for quick and confident interpretation of defects in carbon steel tubes.

  12. Application of the pattern recognition technique to fast reactor acoustic monitoring

    International Nuclear Information System (INIS)

    Brunet, M.; Val, M.

    1981-10-01

    The early detection of operating anomalies is an aim involving the safety of fast reactors. The most likely accident is the complete or partial blocking up of an assembly, one of the signs of which is the boiling of the sodium contained in it. This boiling is accompanied by the production of acoustic waves, the detection of which by appropriate sensors appears to be an efficient way of monitoring the core. For a number of years the CEA has been conducting an experimental programme for studying the detection of boiling by acoustic means. The text presents the various different experiments undertaken and then draws a parallel between the results obtained by conventional processing procedures and those obtained by applying the shape recognition method to the same basic data [fr

  13. A New Fault Location Approach for Acoustic Emission Techniques in Wind Turbines

    Directory of Open Access Journals (Sweden)

    Carlos Quiterio Gómez Muñoz

    2016-01-01

    Full Text Available The renewable energy industry is undergoing continuous improvement and development worldwide, wind energy being one of the most relevant renewable energies. This industry requires high levels of reliability, availability, maintainability and safety (RAMS for wind turbines. The blades are critical components in wind turbines. The objective of this research work is focused on the fault detection and diagnosis (FDD of the wind turbine blades. The FDD approach is composed of a robust condition monitoring system (CMS and a novel signal processing method. CMS collects and analyses the data from different non-destructive tests based on acoustic emission. The acoustic emission signals are collected applying macro-fiber composite (MFC sensors to detect and locate cracks on the surface of the blades. Three MFC sensors are set in a section of a wind turbine blade. The acoustic emission signals are generated by breaking a pencil lead in the blade surface. This method is used to simulate the acoustic emission due to a breakdown of the composite fibers. The breakdown generates a set of mechanical waves that are collected by the MFC sensors. A graphical method is employed to obtain a system of non-linear equations that will be used for locating the emission source. This work demonstrates that a fiber breakage in the wind turbine blade can be detected and located by using only three low cost sensors. It allows the detection of potential failures at an early stages, and it can also reduce corrective maintenance tasks and downtimes and increase the RAMS of the wind turbine.

  14. Demonstration of acoustic resonances in a cylindrical cavity applying the photoacoustic technique

    Science.gov (United States)

    Barreiro, N. L.; Vallespi, A. S.; Zajarevich, N. M.; Peuriot, A. L.; Slezak, V. B.

    2017-09-01

    In this work we present some experiments which can be performed in college or on the first courses of university to acquire knowledge about resonant acoustical phenomena in closed cavities in a tangible way, through experiments based on the photoacoustic effect in gases. This phenomenon consists in the generation of acoustic waves after optical excitation of an absorbing gas and further local heating of the non-absorbing surrounding gas by energy exchange through collisions between molecules of both species. Simple experiments, performed with daily live elements, can be very useful for teachers and students to get in touch with the phenomenon of acoustic resonances with the addition of concepts about light-matter interaction. The setups consist of the resonant cavity, the illumination source and the signal detection-acquisition scheme. In this paper a closed glass test tube is used as the resonant cavity and is filled with a mixture of nitrogen dioxide and air. The illumination is performed by a pulsed power LED modulated at different resonant frequencies of the cavity. A microphone inside the tube is connected to an oscilloscope which displays the photoacoustic signal. The LED is moved along the tube showing how different resonant modes can be excited.

  15. Dislodgement and removal of dust-particles from a surface by a technique combining acoustic standing wave and airflow.

    Science.gov (United States)

    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.

  16. Advanced numerical technique for analysis of surface and bulk acoustic waves in resonators using periodic metal gratings

    Science.gov (United States)

    Naumenko, Natalya F.

    2014-09-01

    A numerical technique characterized by a unified approach for the analysis of different types of acoustic waves utilized in resonators in which a periodic metal grating is used for excitation and reflection of such waves is described. The combination of the Finite Element Method analysis of the electrode domain with the Spectral Domain Analysis (SDA) applied to the adjacent upper and lower semi-infinite regions, which may be multilayered and include air as a special case of a dielectric material, enables rigorous simulation of the admittance in resonators using surface acoustic waves, Love waves, plate modes including Lamb waves, Stonely waves, and other waves propagating along the interface between two media, and waves with transient structure between the mentioned types. The matrix formalism with improved convergence incorporated into SDA provides fast and robust simulation for multilayered structures with arbitrary thickness of each layer. The described technique is illustrated by a few examples of its application to various combinations of LiNbO3, isotropic silicon dioxide and silicon with a periodic array of Cu electrodes. The wave characteristics extracted from the admittance functions change continuously with the variation of the film and plate thicknesses over wide ranges, even when the wave nature changes. The transformation of the wave nature with the variation of the layer thicknesses is illustrated by diagrams and contour plots of the displacements calculated at resonant frequencies.

  17. Real-time implementations of acoustic signal enhancement techniques for aerial based surveillance and rescue applications

    Science.gov (United States)

    Ramos, Antonio L. L.; Shao, Zhili; Holthe, Aleksander; Sandli, Mathias F.

    2017-05-01

    The introduction of the System-on-Chip (SoC) technology has brought exciting new opportunities for the development of smart low cost embedded systems spanning a wide range of applications. Currently available SoC devices are capable of performing high speed digital signal processing tasks in software while featuring relatively low development costs and reduced time-to-market. Unmanned aerial vehicles (UAV) are an application example that has shown tremendous potential in an increasing number of scenarios, ranging from leisure to surveillance as well as in search and rescue missions. Video capturing from UAV platforms is a relatively straightforward task that requires almost no preprocessing. However, that does not apply to audio signals, especially in cases where the data is to be used to support real-time decision making. In fact, the enormous amount of acoustic interference from the surroundings, including the noise from the UAVs propellers, becomes a huge problem. This paper discusses a real-time implementation of the NLMS adaptive filtering algorithm applied to enhancing acoustic signals captured from UAV platforms. The model relies on a combination of acoustic sensors and a computational inexpensive algorithm running on a digital signal processor. Given its simplicity, this solution can be incorporated into the main processing system of an UAV using the SoC technology, and run concurrently with other required tasks, such as flight control and communications. Simulations and real-time DSP-based implementations have shown significant signal enhancement results by efficiently mitigating the interference from the noise generated by the UAVs propellers as well as from other external noise sources.

  18. Timing and technique impact the effectiveness of road-based, mobile acoustic surveys of bats.

    Science.gov (United States)

    D'Acunto, Laura E; Pauli, Benjamin P; Moy, Mikko; Johnson, Kiara; Abu-Omar, Jasmine; Zollner, Patrick A

    2018-03-01

    Mobile acoustic surveys are a common method of surveying bat communities. However, there is a paucity of empirical studies exploring different methods for conducting mobile road surveys of bats. During 2013, we conducted acoustic mobile surveys on three routes in north-central Indiana, U.S.A., using (1) a standard road survey, (2) a road survey where the vehicle stopped for 1 min at every half mile of the survey route (called a "start-stop method"), and (3) a road survey with an individual using a bicycle. Linear mixed models with multiple comparison procedures revealed that when all bat passes were analyzed, using a bike to conduct mobile surveys detected significantly more bat passes per unit time compared to other methods. However, incorporating genus-level comparisons revealed no advantage to using a bike over vehicle-based methods. We also found that survey method had a significant effect when analyses were limited to those bat passes that could be identified to genus, with the start-stop method generally detecting more identifiable passes than the standard protocol or bike survey. Additionally, we found that significantly more identifiable bat passes (particularly those of the Eptesicus and Lasiurus genera) were detected in surveys conducted immediately following sunset. As governing agencies, particularly in North America, implement vehicle-based bat monitoring programs, it is important for researchers to understand how variations on protocols influence the inference that can be gained from different monitoring schemes.

  19. Nondestructive Online Detection of Welding Defects in Track Crane Boom Using Acoustic Emission Technique

    Directory of Open Access Journals (Sweden)

    Yong Tao

    2014-04-01

    Full Text Available Nondestructive detection of structural component of track crane is a difficult and costly problem. In the present study, acoustic emission (AE was used to detect two kinds of typical welding defects, that is, welding porosity and incomplete penetration, in the truck crane boom. Firstly, a subsidiary test specimen with special preset welding defect was designed and added on the boom surface with the aid of steel plates to get the synchronous deformation of the main boom. Then, the AE feature information of the welding defect could be got without influencing normal operation of equipment. As a result, the rudimentary location analysis can be attained using the linear location method and the two kinds of welding defects can be distinguished clearly using AE characteristic parameters such as amplitude and centroid frequency. Also, through the comparison of two loading processes, we concluded that the signal produced during the first loading process was mainly caused by plastic deformation damage and during the second loading process the stress release and structure friction between sections in welding area are the main acoustic emission sources. Thus, the AE is an available tool for nondestructive online detection of latent welding defects of structural component of track crane.

  20. [Acoustic emission diagnostic techniques for high-field high current-density super inducting poles

    International Nuclear Information System (INIS)

    1990-01-01

    Acoustic emission technology was introduced in the late 1970's to monitor superconducting magnets. It has now been firmly established that acoustic signals in superconducting magnets are emitted principally by mechanical events such as conductor strain, conductor motion, frictional motion, and epoxy cracking. Despite earlier suggestions, flux motion, except during flux jumping, does not appear to be an important source of AE signals in superconducting magnets. Of these several potential sources of AE signals in superconducting magnets, mechanical disturbances have been identified to be most important in high-performance, ''adiabatic'' magnets such as the dipoles used in accelerators. These mechanical disturbances are transitory, each generating a packet of AE signals that can be located with sensors. Source identification and location has been achieved with a number of superconducting magnets. In this section, the basic principle for the operation of adiabatic magnets is discussed, followed by presentation of some of the important experimental results relevant to the question of premature quench obtained at MIT

  1. Iterative supervirtual refraction interferometry

    KAUST Repository

    Al-Hagan, Ola

    2014-05-02

    In refraction tomography, the low signal-to-noise ratio (S/N) can be a major obstacle in picking the first-break arrivals at the far-offset receivers. To increase the S/N, we evaluated iterative supervirtual refraction interferometry (ISVI), which is an extension of the supervirtual refraction interferometry method. In this method, supervirtual traces are computed and then iteratively reused to generate supervirtual traces with a higher S/N. Our empirical results with both synthetic and field data revealed that ISVI can significantly boost up the S/N of far-offset traces. The drawback is that using refraction events from more than one refractor can introduce unacceptable artifacts into the final traveltime versus offset curve. This problem can be avoided by careful windowing of refraction events.

  2. Parsimonious Surface Wave Interferometry

    KAUST Repository

    Li, Jing

    2017-10-24

    To decrease the recording time of a 2D seismic survey from a few days to one hour or less, we present a parsimonious surface-wave interferometry method. Interferometry allows for the creation of a large number of virtual shot gathers from just two reciprocal shot gathers by crosscoherence of trace pairs, where the virtual surface waves can be inverted for the S-wave velocity model by wave-equation dispersion inversion (WD). Synthetic and field data tests suggest that parsimonious wave-equation dispersion inversion (PWD) gives S-velocity tomograms that are comparable to those obtained from a full survey with a shot at each receiver. The limitation of PWD is that the virtual data lose some information so that the resolution of the S-velocity tomogram can be modestly lower than that of the S-velocity tomogram inverted from a conventional survey.

  3. Parsimonious Surface Wave Interferometry

    KAUST Repository

    Li, Jing; Hanafy, Sherif; Schuster, Gerard T.

    2017-01-01

    To decrease the recording time of a 2D seismic survey from a few days to one hour or less, we present a parsimonious surface-wave interferometry method. Interferometry allows for the creation of a large number of virtual shot gathers from just two reciprocal shot gathers by crosscoherence of trace pairs, where the virtual surface waves can be inverted for the S-wave velocity model by wave-equation dispersion inversion (WD). Synthetic and field data tests suggest that parsimonious wave-equation dispersion inversion (PWD) gives S-velocity tomograms that are comparable to those obtained from a full survey with a shot at each receiver. The limitation of PWD is that the virtual data lose some information so that the resolution of the S-velocity tomogram can be modestly lower than that of the S-velocity tomogram inverted from a conventional survey.

  4. Iterative supervirtual refraction interferometry

    KAUST Repository

    Al-Hagan, Ola; Hanafy, Sherif M.; Schuster, Gerard T.

    2014-01-01

    In refraction tomography, the low signal-to-noise ratio (S/N) can be a major obstacle in picking the first-break arrivals at the far-offset receivers. To increase the S/N, we evaluated iterative supervirtual refraction interferometry (ISVI), which is an extension of the supervirtual refraction interferometry method. In this method, supervirtual traces are computed and then iteratively reused to generate supervirtual traces with a higher S/N. Our empirical results with both synthetic and field data revealed that ISVI can significantly boost up the S/N of far-offset traces. The drawback is that using refraction events from more than one refractor can introduce unacceptable artifacts into the final traveltime versus offset curve. This problem can be avoided by careful windowing of refraction events.

  5. Scope of neutron interferometry

    International Nuclear Information System (INIS)

    Rauch, H.

    1978-01-01

    This paper deals with the interferometry of well separated coherent beams, where the phase of the beams can be manipulated individually. The basic equation of the dynamical neutron diffraction theory are recalled. The various contributions to the interaction of as low neutron with its surroundings are discussed: the various terms denote the nuclear, magnetic, electromagnetic, intrinsic, gravitational, and weak interaction respectively. Applications to nuclear physics, fundamental physics and solid state physics are successively envisaged

  6. Space Interferometry Science Working Group

    Science.gov (United States)

    Ridgway, Stephen T.

    1992-12-01

    Decisions taken by the astronomy and astrophysics survey committee and the interferometry panel which lead to the formation of the Space Interferometry Science Working Group (SISWG) are outlined. The SISWG was formed by the NASA astrophysics division to provide scientific and technical input from the community in planning for space interferometry and in support of an Astrometric Interferometry Mission (AIM). The AIM program hopes to measure the positions of astronomical objects with a precision of a few millionths of an arcsecond. The SISWG science and technical teams are described and the outcomes of its first meeting are given.

  7. Adaptive parametric model order reduction technique for optimization of vibro-acoustic models: Application to hearing aid design

    Science.gov (United States)

    Creixell-Mediante, Ester; Jensen, Jakob S.; Naets, Frank; Brunskog, Jonas; Larsen, Martin

    2018-06-01

    Finite Element (FE) models of complex structural-acoustic coupled systems can require a large number of degrees of freedom in order to capture their physical behaviour. This is the case in the hearing aid field, where acoustic-mechanical feedback paths are a key factor in the overall system performance and modelling them accurately requires a precise description of the strong interaction between the light-weight parts and the internal and surrounding air over a wide frequency range. Parametric optimization of the FE model can be used to reduce the vibroacoustic feedback in a device during the design phase; however, it requires solving the model iteratively for multiple frequencies at different parameter values, which becomes highly time consuming when the system is large. Parametric Model Order Reduction (pMOR) techniques aim at reducing the computational cost associated with each analysis by projecting the full system into a reduced space. A drawback of most of the existing techniques is that the vector basis of the reduced space is built at an offline phase where the full system must be solved for a large sample of parameter values, which can also become highly time consuming. In this work, we present an adaptive pMOR technique where the construction of the projection basis is embedded in the optimization process and requires fewer full system analyses, while the accuracy of the reduced system is monitored by a cheap error indicator. The performance of the proposed method is evaluated for a 4-parameter optimization of a frequency response for a hearing aid model, evaluated at 300 frequencies, where the objective function evaluations become more than one order of magnitude faster than for the full system.

  8. Measurement of pipe wall thinning by ultra acoustic resonance technique using optical fiber

    International Nuclear Information System (INIS)

    Shirai, Takehiro; Machijima, Yuichi

    2009-01-01

    This is the novel system for Pipe Wall Thickness measurement which is combined EAMT(Electro Magnetic Acoustic Transducer) and Optical Fiber Sensor. The conventional ultrasonic thickness meter is using in pipe wall thickness measurement. However, it is necessary to remove a heat insulator from pipe line. A characteristic of this novel system is that it is possible to measure without removing a heat insulator and on-line monitoring, because of measurement probe is attached between pipe surface and heat insulator. As a result of measured with this system, we could measure 30 mm thickness of carbon and stainless steel at the maximum and pipe specimen of elbow shape. Heat-resistant characteristic confirmed at 200 degrees C until about 7000 hours. (author)

  9. A Methodological Review of Piezoelectric Based Acoustic Wave Generation and Detection Techniques for Structural Health Monitoring

    Directory of Open Access Journals (Sweden)

    Zhigang Sun

    2013-01-01

    Full Text Available Piezoelectric transducers have a long history of applications in nondestructive evaluation of material and structure integrity owing to their ability of transforming mechanical energy to electrical energy and vice versa. As condition based maintenance has emerged as a valuable approach to enhancing continued aircraft airworthiness while reducing the life cycle cost, its enabling structural health monitoring (SHM technologies capable of providing on-demand diagnosis of the structure without interrupting the aircraft operation are attracting increasing R&D efforts. Piezoelectric transducers play an essential role in these endeavors. This paper is set forth to review a variety of ingenious ways in which piezoelectric transducers are used in today’s SHM technologies as a means of generation and/or detection of diagnostic acoustic waves.

  10. Pulsed TV holography measurement and digital reconstruction of compression acoustic wave fields: application to nondestructive testing of thick metallic samples

    International Nuclear Information System (INIS)

    Trillo, C; Doval, A F; Deán-Ben, X L; López-Vázquez, J C; Fernández, J L; Hernández-Montes, S

    2011-01-01

    This paper describes a technique that numerically reconstructs the complex acoustic amplitude (i.e. the acoustic amplitude and phase) of a compression acoustic wave in the interior volume of a specimen from a set of full-field optical measurements of the instantaneous displacement of the surface. The volume of a thick specimen is probed in transmission mode by short bursts of narrowband compression acoustic waves generated at one of its faces. The temporal evolution of the displacement field induced by the bursts emerging at the opposite surface is measured by pulsed digital holographic interferometry (pulsed TV holography). A spatio-temporal 3D Fourier transform processing of the measured data yields the complex acoustic amplitude at the plane of the surface as a sequence of 2D complex-valued maps. Finally, a numerical implementation of the Rayleigh–Sommerfeld diffraction formula is employed to reconstruct the complex acoustic amplitude at other planes in the interior volume of the specimen. The whole procedure can be regarded as a combination of optical digital holography and acoustical holography methods. The technique was successfully tested on aluminium specimens with and without an internal artificial defect and sample results are presented. In particular, information about the shape and position of the defect was retrieved in the experiment performed on the flawed specimen, which indicates the potential applicability of the technique for the nondestructive testing of materials

  11. The determination of acoustic reflection coefficients by using cepstral techniques, II: Extensions of the technique and considerations of accuracy

    Science.gov (United States)

    Bolton, J. S.; Gold, E.

    1986-10-01

    In a companion paper the cepstral technique for the measurement of reflection coefficients was described. In particular the concepts of extraction noise and extraction delay were introduced. They are considered further here, and, in addition, a means of extending the cepstral technique to accommodate surfaces having lengthy impulse responses is described. The character of extraction noise, a cepstral component which interferes with reflection measurements, is largely determined by the spectrum of the signal radiated from the source loudspeaker. Here the origin and effects of extraction noise are discussed and it is shown that inverse filtering techniques may be used to reduce extraction noise without making impractical demands of the electrical test signal or the source loudspeaker. The extraction delay, a factor which is introduced when removing the reflector impulse response from the power cepstrum, has previously been estimated by a cross-correlation technique. Here the importance of estimating the extraction delay accurately is emphasized by showing the effect of small spurious delays on the calculation of the normal impedance of a reflecting surface. The effects are shown to accord with theory, and it was found that the real part of the estimated surface normal impedance is very nearly maximized when the spurious delay is eliminated; this has suggested a new way of determining the extraction delay itself. Finally, the basic cepstral technique is suited only to the measurement of surfaces whose impulse responses are shorter than τ, the delay between the arrival of the direct and specularly reflected components at the measurement position. Here it is shown that this restriction can be eliminated, by using a process known as cepstral inversion, when the direct cepstrum has a duration less than τ and cepstral aliasing is insignificant. It is also possible to use this technique to deconvolve a signal from an echo sequence in the time domain, an operation

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Ahmad Zaki

    2015-08-01

    Full Text Available 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.

  14. Acoustic Modifications of the Ames 40x80 Foot Wind Tunnel and Test Techniques for High-Speed Research Model Testing

    Science.gov (United States)

    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.

  15. Optical interferometry for biology and medicine

    CERN Document Server

    Nolte, David D

    2012-01-01

    This book presents the fundamental physics of optical interferometry as applied to biophysical, biological and medical research. Interference is at the core of many types of optical detection and is a powerful probe of cellular and tissue structure in interfererence microscopy and in optical coherence tomography. It is also the root cause of speckle and other imaging artefacts that limit range and resolution. For biosensor applications, the inherent sensitivity of interferometry enables ultrasensitive detection of molecules in biological samples for medical diagnostics. In this book, emphasis is placed on the physics of light scattering, beginning with the molecular origins of refraction as light propagates through matter, and then treating the stochastic nature of random fields that ultimately dominate optical imaging in cells and tissue. The physics of partial coherence plays a central role in the text, with a focus on coherence detection techniques that allow information to be selectively detected out of ...

  16. Interferometry with atoms

    International Nuclear Information System (INIS)

    Helmcke, J.; Riehle, F.; Witte, A.; Kisters, T.

    1992-01-01

    Physics and experimental results of atom interferometry are reviewed and several realizations of atom interferometers are summarized. As a typical example of an atom interferometer utilizing the internal degrees of freedom of the atom, we discuss the separated field excitation of a calcium atomic beam using four traveling laser fields and demonstrate the Sagnac effect in a rotating interferometer. The sensitivity of this interferometer can be largely increased by use of slow atoms with narrow velocity distribution. We therefore furthermore report on the preparation of a laser cooled and deflected calcium atomic beam. (orig.)

  17. Criteria for assessing the quality of signal processing techniques for acoustic leak detection

    International Nuclear Information System (INIS)

    Prabhakar, R.; Singh, O.P.

    1990-01-01

    In this paper the criteria used in the first IAEA coordinated research programme to assess the quality of signal processing techniques for sodium boiling noise detection are highlighted. Signal processing techniques, using new features sensitive to boiling and a new approach for achieving higher reliability of detection, which were developed at Indira Gandhi Centre for Atomic Research are also presented. 10 refs, 3 figs, 2 tabs

  18. A Century of Acoustic Metrology

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1998-01-01

    The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect.......The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect....

  19. Visualization and direct comparison of large displacements using difference holographic interferometry

    International Nuclear Information System (INIS)

    Necati Ecevit, F.; Aydin, R.

    1994-01-01

    The difference holographic interferometry provides the possibility of direct comparison of large displacements and deformations of two similar but different objects by application of a special kind of illumination. In this work, the principles of the difference holographic interferometry and the experimental results obtained by applying the single beam technique to large displacements is presented. (author). 10 refs, 4 figs

  20. Generation of Bell, NOON and W states via atom interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Rameez-ul; Saif, Farhan [Department of Electronics, Quaid-i-Azam University, Islamabad (Pakistan); Khosa, Ashfaq H [Centre for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)

    2008-02-14

    We propose atom interferometric techniques for the generation of Bell, NOON and W states of an electromagnetic field in high-Q cavities. The fundamental constituent of these techniques is off-resonant Bragg diffraction of atomic de Broglie waves. We show good success probabilities for these schemes under the currently available experimental environment of atom interferometry.

  1. Radio astronomical interferometry and x-ray's computerized tomography

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, L F [Universidad Nacional Autonoma de Mexico, Mexico City. Inst. de Astronomia

    1982-01-01

    Radio astronomical interferometry and computerized tomography are techniques of great importance for astronomy and medicine, respectively. In this paper we emphasize that both techniques are based on the same mathematical principles, and present them as an example of interaction between basic and applied science.

  2. Michelson wide-field stellar interferometry : Principles and experimental verification

    NARCIS (Netherlands)

    Montilla, I.; Pereira, S.F.; Braat, J.J.M.

    2005-01-01

    A new interferometric technique for Michelson wide-field interferometry is presented that consists of a Michelson pupil-plane combination scheme in which a wide field of view can be achieved in one shot. This technique uses a stair-shaped mirror in the intermediate image plane of each telescope in

  3. Speckle interferometry of asteroids

    International Nuclear Information System (INIS)

    Drummond, J.

    1988-01-01

    By studying the image two-dimensional power spectra or autocorrelations projected by an asteroid as it rotates, it is possible to locate its rotational pole and derive its three axes dimensions through speckle interferometry under certain assumptions of uniform, geometric scattering, and triaxial ellipsoid shape. However, in cases where images can be reconstructed, the need for making the assumptions is obviated. Furthermore, the ultimate goal for speckle interferometry of image reconstruction will lead to mapping albedo features (if they exist) as impact areas or geological units. The first glimpses of the surface of an asteroid were obtained from images of 4 Vesta reconstructed from speckle interferometric observations. These images reveal that Vesta is quite Moon-like in having large hemispheric-scale albedo features. All of its lightcurves can be produced from a simple model developed from the images. Although undoubtedly more intricate than the model, Vesta's lightcurves can be matched by a model with three dark and four bright spots. The dark areas so dominate one hemisphere that a lightcurve minimum occurs when the maximum cross-section area is visible. The triaxial ellipsoid shape derived for Vesta is not consistent with the notion that the asteroid has an equilibrium shape in spite of its having apparently been differentiated

  4. Shift of the Acoustic Center of a Closed-Box Loudspeaker in a Linear Array: Investigation Using the Beamforming Technique

    DEFF Research Database (Denmark)

    Chang, Ji-Ho; Jensen, Joe; Agerkvist, Finn T.

    2015-01-01

    The center of the spherical waves radiated from a loudspeaker is defined as its acoustic center. This study aims to investigate how the acoustic center of a closed-box loudspeaker is shifted when the loudspeaker is placed in a linear array. That is, the acoustic center of the loudspeaker is estim......The center of the spherical waves radiated from a loudspeaker is defined as its acoustic center. This study aims to investigate how the acoustic center of a closed-box loudspeaker is shifted when the loudspeaker is placed in a linear array. That is, the acoustic center of the loudspeaker...... is estimated when the loudspeaker is placed alone and then the loudspeaker is placed in a linear array composed of two or three identical loudspeakers. The acoustic center of each loudspeaker in the linear arrays is estimated with the other loudspeakers turned off and compared with that in the single...... that the acoustic center is shifted differently depending on the relative position of the loudspeaker in the array. This implies that the performance of sound field control with a linear array of loudspeakers can be improved by taking the shift of the acoustic center into account....

  5. Optical metrology techniques for dimensional stability measurements

    NARCIS (Netherlands)

    Ellis, Jonathan David

    2010-01-01

    This thesis work is optical metrology techniques to determine material stability. In addition to displacement interferometry, topics such as periodic nonlinearity, Fabry-Perot interferometry, refractometry, and laser stabilization are covered.

  6. Interferometry and synthesis in radio astronomy

    CERN Document Server

    Thompson, A Richard; Swenson Jr , George W

    2017-01-01

    This book is open access under a CC BY-NC 4.0 license. The third edition of this indispensable book in radio interferometry provides extensive updates to the second edition, including results and technical advances from the past decade; discussion of arrays that now span the full range of the radio part of the electromagnetic spectrum observable from the ground, 10 MHz to 1 THz; an analysis of factors that affect array speed; and an expanded discussion of digital signal-processing techniques and of scintillation phenomena and the effects of atmospheric water vapor on image distortion, among many other topics. With its comprehensiveness and detailed exposition of all aspects of the theory and practice of radio interferometry and synthesis imaging, this book has established itself as a standard reference in the field. It begins with an overview of the basic principles of radio astronomy, a short history of the development of radio interferometry, and an elementary discussion of the operation of an interferomete...

  7. Analysis of surface absorbed dose in X-ray grating interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhili, E-mail: wangnsrl@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026 (China); Wu, Zhao; Gao, Kun; Wang, Dajiang; Chen, Heng; Wang, Shenghao [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026 (China); Wu, Ziyu, E-mail: wuzy@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026 (China); Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2014-10-15

    Highlights: • Theoretical framework for dose estimation in X-ray grating interferometry. • Potential dose reduction of X-ray grating interferometry compared to conventional radiography. • Guidelines for optimization of X-ray grating interferometry for dose-sensitive applications. • Measure to compare various existing X-ray phase contrast imaging techniques. - Abstract: X-ray phase contrast imaging using grating interferometry has shown increased contrast over conventional absorption imaging, and therefore the great potential of dose reduction. The extent of the dose reduction depends on the geometry of grating interferometry, the photon energy, the properties of the sample under investigation and the utilized detector. These factors also determine the capability of grating interferometry to distinguish between different tissues with a specified statistical certainty in a single raw image. In this contribution, the required photon number for imaging and the resulting surface absorbed dose are determined in X-ray grating interferometry, using a two-component imaging object model. The presented results confirm that compared to conventional radiography, phase contrast imaging using grating interferometry indeed has the potential of dose reduction. And the extent of dose reduction is strongly dependent on the imaging conditions. Those results provide a theoretical framework for dose estimation under given imaging conditions before experimental trials, and general guidelines for optimization of grating interferometry for those dose-sensitive applications.

  8. Analysis of surface absorbed dose in X-ray grating interferometry

    International Nuclear Information System (INIS)

    Wang, Zhili; Wu, Zhao; Gao, Kun; Wang, Dajiang; Chen, Heng; Wang, Shenghao; Wu, Ziyu

    2014-01-01

    Highlights: • Theoretical framework for dose estimation in X-ray grating interferometry. • Potential dose reduction of X-ray grating interferometry compared to conventional radiography. • Guidelines for optimization of X-ray grating interferometry for dose-sensitive applications. • Measure to compare various existing X-ray phase contrast imaging techniques. - Abstract: X-ray phase contrast imaging using grating interferometry has shown increased contrast over conventional absorption imaging, and therefore the great potential of dose reduction. The extent of the dose reduction depends on the geometry of grating interferometry, the photon energy, the properties of the sample under investigation and the utilized detector. These factors also determine the capability of grating interferometry to distinguish between different tissues with a specified statistical certainty in a single raw image. In this contribution, the required photon number for imaging and the resulting surface absorbed dose are determined in X-ray grating interferometry, using a two-component imaging object model. The presented results confirm that compared to conventional radiography, phase contrast imaging using grating interferometry indeed has the potential of dose reduction. And the extent of dose reduction is strongly dependent on the imaging conditions. Those results provide a theoretical framework for dose estimation under given imaging conditions before experimental trials, and general guidelines for optimization of grating interferometry for those dose-sensitive applications

  9. Acoustical holographic Siamese image technique for imaging radial cracks in reactor piping

    International Nuclear Information System (INIS)

    Collins, H.D.; Gribble, R.P.

    1985-04-01

    This paper describes a unique technique (i.e., ''Siamese imaging'') for imaging quasi-vertical defects in reactor pipe weldments. The Siamese image is a bi-symmetrical view of the inner surface defect. Image construction geometry consists of two probes (i.e., source/receiver) operating either from opposite sides or the same side of the defect to be imaged. As the probes are scanned across a lower surface connected defect, they encounter two images - first the normal upright image and then the inverted image. The final integrated image consists of two images connected along their baselines, thus we call it a ''Siamese image.'' The experimental imaging results on simulated and natural cracks in reactor piping weldments graphically illustrate this unique technique. Excellent images of mechanical fatique and thermal cracks were obtained on ferritic and austenitic piping

  10. Preliminary interferometry measurements of a flow field around fluttering NACA0015 profile

    Czech Academy of Sciences Publication Activity Database

    Vlček, Václav; Kozánek, Jan

    2011-01-01

    Roč. 56, č. 4 (2011), s. 379-387 ISSN 0001-7043 R&D Projects: GA ČR GA101/09/1522 Institutional research plan: CEZ:AV0Z20760514 Keywords : self-excited vibration * airfoil * aerodynamic tunnel * interferometry Subject RIV: BI - Acoustics http://journal.it.cas.cz

  11. Precision measurement with atom interferometry

    International Nuclear Information System (INIS)

    Wang Jin

    2015-01-01

    Development of atom interferometry and its application in precision measurement are reviewed in this paper. The principle, features and the implementation of atom interferometers are introduced, the recent progress of precision measurement with atom interferometry, including determination of gravitational constant and fine structure constant, measurement of gravity, gravity gradient and rotation, test of weak equivalence principle, proposal of gravitational wave detection, and measurement of quadratic Zeeman shift are reviewed in detail. Determination of gravitational redshift, new definition of kilogram, and measurement of weak force with atom interferometry are also briefly introduced. (topical review)

  12. An Evaluation of the Acoustic Signal processing Techniques for Sodium-Water Reaction Detection in KALIMER-600

    International Nuclear Information System (INIS)

    Hur, Seop; Seong, S. H.; Kim, T. J.; Kim, S. O.; Lee, M. K.

    2005-02-01

    KALIMER-600 is a pool type fast breeder reactor using liquid sodium as a coolant. Although it has the several advantages such as long-term fuel cycle and enhanced safety concepts, it is possible to leak the secondary side water/steam into sodium boundary. This event could make the plant abnormal condition. One of the major design issues in KALIMER-600 is, therefore, to develop the system which can early detect the sodium-water reaction to protect the sodium-water reaction event. After evaluating the various signal processing techniques for passive acoustic leak detection, we have proposed the early leak detection logics. the signal processing techniques for evaluation were the spectral estimation using the linear modeling, the estimation error of linear modeling, the system adaptation rate using an adaptive signal processing, and the background noise cancellation using adaptive and fixed filtering. As the analysis results regarding the stationary and the cross-correlation of leak signals and background noises, the two signal systems met a wide-dense stationary process and there was only the week cross correlation relationship between two signals. It is ,therefore, possible to use the linear/harmonic modeling of signal systems, and the leak signal in sensor outputs can be discriminated. As the results of the evaluation of the various spectral estimation methods, the spectral estimation method based on autoregressive modeling was more practical comparing with other methods in the sodium-water reaction detection. The passive acoustic leak detection logics were suggested based on above evaluations. the logics consist of 3 levels; transient identification, leak determination and leak symptom identification. The simulation results using sodium-water reaction signals showed that it was possible to determine the leak at above -3dB of SNR, while between -3 dB and -10 dB of SNR the logics determined the leak symptom identification. The detection sensitivity can be enhanced

  13. Pipeline monitoring with interferometry in non-arid regions

    Energy Technology Data Exchange (ETDEWEB)

    McCardle, Adrian; Rabus, Bernhard; Ghuman, Parwant [MacDonald Dettwiler, Richmond, BC (Canada); Freymueller, Jeff T. [University of Alaska, Fairbanks (United States)

    2005-07-01

    Interferometry has become a proven technique for accurately measuring ground movements caused by subsidence, landslides, earthquakes and volcanoes. Using space borne sensors such as the ERS, ENVISAT and RADARSAT satellites, ground deformation can be monitored on a millimeter level. Traditionally interferometry has been limited to arid areas however new technology has allowed for successful monitoring in vegetated regions and areas of changing land-cover. Analysis of ground movement of the Trans-Alaskan pipeline demonstrates how these techniques can offer pipeline engineers a new tool for observing potential dangers to pipeline integrity. Results from Interferometric Point Target Analysis were compared with GPS measurements and speckle tracking interferometry was demonstrated to measure a major earthquake. (author)

  14. Practical optical interferometry imaging at visible and infrared wavelengths

    CERN Document Server

    Buscher, David F

    2015-01-01

    Optical interferometry is a powerful technique to make images on angular scales hundreds of times smaller than is possible with the largest telescopes. This concise guide provides an introduction to the technique for graduate students and researchers who want to make interferometric observations and acts as a reference for technologists building new instruments. Starting from the principles of interference, the author covers the core concepts of interferometry, showing how the effects of the Earth's atmosphere can be overcome using closure phase, and the complete process of making an observation, from planning to image reconstruction. This rigorous approach emphasizes the use of rules-of-thumb for important parameters such as the signal-to-noise ratios, requirements for sampling the Fourier plane and predicting image quality. The handbook is supported by web resources, including the Python source code used to make many of the graphs, as well as an interferometry simulation framework, available at www.cambridg...

  15. Development of Acoustic Model-Based Iterative Reconstruction Technique for Thick-Concrete Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Almansouri, Hani [Purdue University; Clayton, Dwight A [ORNL; Kisner, Roger A [ORNL; Polsky, Yarom [ORNL; Bouman, Charlie [Purdue University; Santos-Villalobos, Hector J [ORNL

    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.

  16. Development of Acoustic Model-Based Iterative Reconstruction Technique for Thick-Concrete Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Almansouri, Hani [Purdue University; Clayton, Dwight A [ORNL; Kisner, Roger A [ORNL; Polsky, Yarom [ORNL; Bouman, Charlie [Purdue University; Santos-Villalobos, Hector J [ORNL

    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.

  17. Development of acoustic model-based iterative reconstruction technique for thick-concrete imaging

    Science.gov (United States)

    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

  18. Parsimonious refraction interferometry

    KAUST Repository

    Hanafy, Sherif

    2016-09-06

    We present parsimonious refraction interferometry where a densely populated refraction data set can be obtained from just two shot gathers. The assumptions are that the first arrivals are comprised of head waves and direct waves, and a pair of reciprocal shot gathers is recorded over the line of interest. The refraction traveltimes from these reciprocal shot gathers can be picked and decomposed into O(N2) refraction traveltimes generated by N virtual sources, where N is the number of geophones in the 2D survey. This enormous increase in the number of virtual traveltime picks and associated rays, compared to the 2N traveltimes from the two reciprocal shot gathers, allows for increased model resolution and better condition numbers in the normal equations. Also, a reciprocal survey is far less time consuming than a standard refraction survey with a dense distribution of sources.

  19. Interferometry with Vortices

    Directory of Open Access Journals (Sweden)

    P. Senthilkumaran

    2012-01-01

    Full Text Available Interference of optical beams with optical vortices is often encountered in singular optics. Since interferometry makes the phase observable by intensity measurement, it brings out a host of applications and helps to understand the optical vortex. In this article we present an optical vortex interferometer that can be used in optical testing and has the potential to increase the accuracy of measurements. In an optical vortex interferometer (OVI, a lattice of vortices is formed, and the movement of the cores of these vortices is tracked when one of the interfering beams is deformed. Instead of multiple vortices in an OVI, an isolated single vortex also finds applications in optical testing. Finally, singularity in scalar and vector fields is presented, and the relation between them is illustrated by the superposition of these beams.

  20. Parsimonious refraction interferometry

    KAUST Repository

    Hanafy, Sherif; Schuster, Gerard T.

    2016-01-01

    We present parsimonious refraction interferometry where a densely populated refraction data set can be obtained from just two shot gathers. The assumptions are that the first arrivals are comprised of head waves and direct waves, and a pair of reciprocal shot gathers is recorded over the line of interest. The refraction traveltimes from these reciprocal shot gathers can be picked and decomposed into O(N2) refraction traveltimes generated by N virtual sources, where N is the number of geophones in the 2D survey. This enormous increase in the number of virtual traveltime picks and associated rays, compared to the 2N traveltimes from the two reciprocal shot gathers, allows for increased model resolution and better condition numbers in the normal equations. Also, a reciprocal survey is far less time consuming than a standard refraction survey with a dense distribution of sources.

  1. Acoustic biosensors.

    Science.gov (United States)

    Fogel, Ronen; Limson, Janice; Seshia, Ashwin A

    2016-06-30

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. © 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  2. Interferometry using undulator sources

    International Nuclear Information System (INIS)

    Beguiristain, R.; Goldberg, K.A.; Tejnil, E.; Bokor, J.; Medecki, H.; Attwood, D.T.; Jackson, K.

    1996-01-01

    Optical systems for extreme ultraviolet (EUV) lithography need to use optical components with subnanometer surface figure error tolerances to achieve diffraction-limited performance [M.D. Himel, in Soft X-Ray Projection Lithography, A.M. Hawryluk and R.H. Stulen, eds. (OSA, Washington, D.C., 1993), 18, 1089, and D. Attwood et al., Appl. Opt. 32, 7022 (1993)]. Also, multilayer-coated optics require at-wavelength wavefront measurement to characterize phase effects that cannot be measured by conventional optical interferometry. Furthermore, EUV optical systems will additionally require final testing and alignment at the operational wavelength for adjustment and reduction of the cumulative optical surface errors. Therefore, at-wavelength interferometric measurement of EUV optics will be the necessary metrology tool for the successful development of optics for EUV lithography. An EUV point diffraction interferometer (PDI) has been developed at the Center for X-Ray Optics (CXRO) and has been already in operation for a year [K. Goldberg et al., in Extreme Ultra Lithography, D.T. Attwood and F. Zernike, eds. (OSA, Washington, D.C., 1994), K. Goldberg et al., Proc. SPIE 2437, to be published, and K. Goldberg et al., J. Vac. Sci. Technol. B 13, 2923 (1995)] using an undulator radiation source and coherent optics beamline at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. An overview of the PDI interferometer and some EUV wavefront measurements obtained with this instrument will be presented. In addition, future developments planned for EUV interferometry at CXRO towards the measurement of actual EUV lithography optics will be shown. copyright 1996 American Institute of Physics

  3. Parsimonious Refraction Interferometry and Tomography

    KAUST Repository

    Hanafy, Sherif; Schuster, Gerard T.

    2017-01-01

    We present parsimonious refraction interferometry and tomography where a densely populated refraction data set can be obtained from two reciprocal and several infill shot gathers. The assumptions are that the refraction arrivals are head waves

  4. Acoustic Emission Signal Processing Technique to Characterize Reactor In-Pile Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. A study of aluminum-lithium alloy solidification using acoustic emission techniques. Ph.D. Thesis, 1991

    Science.gov (United States)

    Henkel, Daniel P.

    1992-01-01

    Physical phenomena associated with the solidification of an aluminum lithium alloy was characterized using acoustic emission (AE) techniques. It is shown that repeatable patterns of AE activity may be correlated to microstructural changes that occur during solidification. The influence of the experimental system on generated signals was examined in the time and frequency domains. The analysis was used to show how an AE signal from solidifying aluminum is changed by each component in the detection system to produce a complex waveform. Conventional AE analysis has shown that a period of high AE activity occurs in pure aluminum, an Al-Cu alloy, and the Al-Li alloy, as the last fraction of solid forms. A model attributes this to the internal stresses of grain boundary formation. An additional period of activity occurs as the last fraction of solid forms, but only in the two alloys. A model attributes this to the formation of interdendritic porosity which was not present in the pure aluminum. The AE waveforms were dominated by resonant effects of the waveguide and the transducer.

  6. Detection of coffee flavour ageing by solid-phase microextraction/surface acoustic wave sensor array technique (SPME/SAW).

    Science.gov (United States)

    Barié, Nicole; Bücking, Mark; Stahl, Ullrich; Rapp, Michael

    2015-06-01

    The use of polymer coated surface acoustic wave (SAW) sensor arrays is a very promising technique for highly sensitive and selective detection of volatile organic compounds (VOCs). We present new developments to achieve a low cost sensor setup with a sampling method enabling the highly reproducible detection of volatiles even in the ppb range. Since the VOCs of coffee are well known by gas chromatography (GC) research studies, the new sensor array was tested for an easy assessable objective: coffee ageing during storage. As reference method these changes were traced with a standard GC/FID set-up, accompanied by sensory panellists. The evaluation of GC data showed a non-linear characteristic for single compound concentrations as well as for total peak area values, disabling prediction of the coffee age. In contrast, the new SAW sensor array demonstrates a linear dependency, i.e. being capable to show a dependency between volatile concentration and storage time. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Online study of cracks during laser cladding process based on acoustic emission technique and finite element analysis

    International Nuclear Information System (INIS)

    Wang Fujun; Mao Huaidong; Zhang Dawei; Zhao Xingyu; Shen Yu

    2008-01-01

    This paper presents a novel method by using acoustic emission technique to online study of the crack generation and expansion during laser cladding process. The cracks during laser cladding processes with five different laser cladding powder materials were online tested, respectively, with this method. Through finite element analysis (FEA), the temperature ranges of crack generation and expansion were figured out. The main forms and extended forms of the cracks were investigated by using optical microscope and scanning electron microscope (SEM). The experiment and analysis results show that the amount of cracks increases with the area and thickness of coating and the cooling rate increasing. A majority of cracks occur in the bonding zone and extend cross the whole cladding coating along the perpendicular direction of laser scanning during laser cladding, and few cracks generate in the cooling process. There are mainly four kinds of crack forms, and the forms of crack expansion are related to the stress states of coating and substrate. The method and conclusions in this paper provide important information for reducing the cracks during large area laser cladding process.

  8. Astrophysical techniques

    CERN Document Server

    Kitchin, CR

    2013-01-01

    DetectorsOptical DetectionRadio and Microwave DetectionX-Ray and Gamma-Ray DetectionCosmic Ray DetectorsNeutrino DetectorsGravitational Radiation Dark Matter and Dark Energy Detection ImagingThe Inverse ProblemPhotographyElectronic ImagingScanningInterferometrySpeckle InterferometryOccultationsRadarElectronic ImagesPhotometryPhotometryPhotometersSpectroscopySpectroscopy SpectroscopesOther TechniquesAstrometryPolarimetrySolar StudiesMagnetometryComputers and The Internet.

  9. Spectral Interferometry with Electron Microscopes

    Science.gov (United States)

    Talebi, Nahid

    2016-01-01

    Interference patterns are not only a defining characteristic of waves, but also have several applications; characterization of coherent processes and holography. Spatial holography with electron waves, has paved the way towards space-resolved characterization of magnetic domains and electrostatic potentials with angstrom spatial resolution. Another impetus in electron microscopy has been introduced by ultrafast electron microscopy which uses pulses of sub-picosecond durations for probing a laser induced excitation of the sample. However, attosecond temporal resolution has not yet been reported, merely due to the statistical distribution of arrival times of electrons at the sample, with respect to the laser time reference. This is however, the very time resolution which will be needed for performing time-frequency analysis. These difficulties are addressed here by proposing a new methodology to improve the synchronization between electron and optical excitations through introducing an efficient electron-driven photon source. We use focused transition radiation of the electron as a pump for the sample. Due to the nature of transition radiation, the process is coherent. This technique allows us to perform spectral interferometry with electron microscopes, with applications in retrieving the phase of electron-induced polarizations and reconstructing dynamics of the induced vector potential. PMID:27649932

  10. Isotope Analysis of Uranium by Interferometry; Analyse isotopique de l'uranium par interferometrie

    Energy Technology Data Exchange (ETDEWEB)

    Leicknam, J P [Commissariat a l' Energie Atomique. Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

    1962-07-01

    Among the optical methods which may be used to make isotopic measurements of {sup 235}U interferometry gives promising results. An apparatus is described which has a photomultiplier as receiver; the source must therefore have characteristics (intensity, stability, fineness of emitted rays) which have led to the use of electrode-less discharge tubes whose methods of production and excitation are given. An example of calibration is given. (author) [French] Parmi les methodes optiques permettant le dosage isotopique de l'uranium 235, l'interferometrie est une technique qui donne des resultats prometteurs. On decrit ici un appareil ayant un photo-multiplicateur comme recepteur; la source doit donc avoir des caracteristiques (intensite, stabilite, finesse des raies emises) qui ont conduit a utiliser des tubes a decharge sans electrode dont on indique la fabrication et le mode d'excitation. Un exemple d'etalonnage est enfin donne. (auteur)

  11. A technique for the deconvolution of the pulse shape of acoustic emission signals back to the generating defect source

    International Nuclear Information System (INIS)

    Houghton, J.R.; Packman, P.F.; Townsend, M.A.

    1976-01-01

    Acoustic emission signals recorded after passage through the instrumentation system can be deconvoluted to produce signal traces indicative of those at the generating source, and these traces can be used to identify characteristics of the source

  12. Deformation measurement of a pressure vessel flange by holographic interferometry

    International Nuclear Information System (INIS)

    Goncalves Junior, Armando A.; Schneider, C.A.

    1984-01-01

    An automatic metodology used for the measurement of displacement through the holographic interferometry is presented. In order to shown its performance and potentiality, the displacement field from a pipe's and flange, when submited to an internal pressure, is experimentally found. Holography's results are compared with other technique's results. (Author) [pt

  13. A publication database for optical long baseline interferometry

    Science.gov (United States)

    Malbet, Fabien; Mella, Guillaume; Lawson, Peter; Taillifet, Esther; Lafrasse, Sylvain

    2010-07-01

    Optical long baseline interferometry is a technique that has generated almost 850 refereed papers to date. The targets span a large variety of objects from planetary systems to extragalactic studies and all branches of stellar physics. We have created a database hosted by the JMMC and connected to the Optical Long Baseline Interferometry Newsletter (OLBIN) web site using MySQL and a collection of XML or PHP scripts in order to store and classify these publications. Each entry is defined by its ADS bibcode, includes basic ADS informations and metadata. The metadata are specified by tags sorted in categories: interferometric facilities, instrumentation, wavelength of operation, spectral resolution, type of measurement, target type, and paper category, for example. The whole OLBIN publication list has been processed and we present how the database is organized and can be accessed. We use this tool to generate statistical plots of interest for the community in optical long baseline interferometry.

  14. Coda Wave Interferometry Method Applied in Structural Monitoring to Assess Damage Evolution in Masonry and Concrete Structures

    International Nuclear Information System (INIS)

    Masera, D; Bocca, P; Grazzini, A

    2011-01-01

    In this experimental program the main goal is to monitor the damage evolution in masonry and concrete structures by Acoustic Emission (AE) signal analysis applying a well-know seismic method. For this reason the concept of the coda wave interferometry is applied to AE signal recorded during the tests. Acoustic Emission (AE) are very effective non-destructive techniques applied to identify micro and macro-defects and their temporal evolution in several materials. This technique permits to estimate the velocity of ultrasound waves propagation and the amount of energy released during fracture propagation to obtain information on the criticality of the ongoing process. By means of AE monitoring, an experimental analysis on a set of reinforced masonry walls under variable amplitude loading and strengthening reinforced concrete (RC) beams under monotonic static load has been carried out. In the reinforced masonry wall, cyclic fatigue stress has been applied to accelerate the static creep and to forecast the corresponding creep behaviour of masonry under static long-time loading. During the tests, the evaluation of fracture growth is monitored by coda wave interferometry which represents a novel approach in structural monitoring based on AE relative change velocity of coda signal. In general, the sensitivity of coda waves has been used to estimate velocity changes in fault zones, in volcanoes, in a mining environment, and in ultrasound experiments. This method uses multiple scattered waves, which travelled through the material along numerous paths, to infer tiny temporal changes in the wave velocity. The applied method has the potential to be used as a 'damage-gauge' for monitoring velocity changes as a sign of damage evolution into masonry and concrete structures.

  15. Coda Wave Interferometry Method Applied in Structural Monitoring to Assess Damage Evolution in Masonry and Concrete Structures

    Energy Technology Data Exchange (ETDEWEB)

    Masera, D; Bocca, P; Grazzini, A, E-mail: davide.masera@polito.it [Department of Structural and Geotechnical Engineering - Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Turin (Italy)

    2011-07-19

    In this experimental program the main goal is to monitor the damage evolution in masonry and concrete structures by Acoustic Emission (AE) signal analysis applying a well-know seismic method. For this reason the concept of the coda wave interferometry is applied to AE signal recorded during the tests. Acoustic Emission (AE) are very effective non-destructive techniques applied to identify micro and macro-defects and their temporal evolution in several materials. This technique permits to estimate the velocity of ultrasound waves propagation and the amount of energy released during fracture propagation to obtain information on the criticality of the ongoing process. By means of AE monitoring, an experimental analysis on a set of reinforced masonry walls under variable amplitude loading and strengthening reinforced concrete (RC) beams under monotonic static load has been carried out. In the reinforced masonry wall, cyclic fatigue stress has been applied to accelerate the static creep and to forecast the corresponding creep behaviour of masonry under static long-time loading. During the tests, the evaluation of fracture growth is monitored by coda wave interferometry which represents a novel approach in structural monitoring based on AE relative change velocity of coda signal. In general, the sensitivity of coda waves has been used to estimate velocity changes in fault zones, in volcanoes, in a mining environment, and in ultrasound experiments. This method uses multiple scattered waves, which travelled through the material along numerous paths, to infer tiny temporal changes in the wave velocity. The applied method has the potential to be used as a 'damage-gauge' for monitoring velocity changes as a sign of damage evolution into masonry and concrete structures.

  16. Partial discharge localization in power transformers based on the sequential quadratic programming-genetic algorithm adopting acoustic emission techniques

    Science.gov (United States)

    Liu, Hua-Long; Liu, Hua-Dong

    2014-10-01

    Partial discharge (PD) in power transformers is one of the prime reasons resulting in insulation degradation and power faults. Hence, it is of great importance to study the techniques of the detection and localization of PD in theory and practice. The detection and localization of PD employing acoustic emission (AE) techniques, as a kind of non-destructive testing, plus due to the advantages of powerful capability of locating and high precision, have been paid more and more attention. The localization algorithm is the key factor to decide the localization accuracy in AE localization of PD. Many kinds of localization algorithms exist for the PD source localization adopting AE techniques including intelligent and non-intelligent algorithms. However, the existed algorithms possess some defects such as the premature convergence phenomenon, poor local optimization ability and unsuitability for the field applications. To overcome the poor local optimization ability and easily caused premature convergence phenomenon of the fundamental genetic algorithm (GA), a new kind of improved GA is proposed, namely the sequence quadratic programming-genetic algorithm (SQP-GA). For the hybrid optimization algorithm, SQP-GA, the sequence quadratic programming (SQP) algorithm which is used as a basic operator is integrated into the fundamental GA, so the local searching ability of the fundamental GA is improved effectively and the premature convergence phenomenon is overcome. Experimental results of the numerical simulations of benchmark functions show that the hybrid optimization algorithm, SQP-GA, is better than the fundamental GA in the convergence speed and optimization precision, and the proposed algorithm in this paper has outstanding optimization effect. At the same time, the presented SQP-GA in the paper is applied to solve the ultrasonic localization problem of PD in transformers, then the ultrasonic localization method of PD in transformers based on the SQP-GA is proposed. And

  17. Landau-Zener-Stueckelberg interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Shevchenko, S.N., E-mail: sshevchenko@ilt.kharkov.u [B.Verkin Institute for Low Temperature Physics and Engineering, Kharkov (Ukraine); RIKEN Advanced Science Institute, Wako-shi, Saitama (Japan); Ashhab, S.; Nori, Franco [RIKEN Advanced Science Institute, Wako-shi, Saitama (Japan); Department of Physics, The University of Michigan, Ann Arbor, MI (United States)

    2010-07-15

    A transition between energy levels at an avoided crossing is known as a Landau-Zener transition. When a two-level system (TLS) is subject to periodic driving with sufficiently large amplitude, a sequence of transitions occurs. The phase accumulated between transitions (commonly known as the Stueckelberg phase) may result in constructive or destructive interference. Accordingly, the physical observables of the system exhibit periodic dependence on the various system parameters. This phenomenon is often referred to as Landau-Zener-Stueckelberg (LZS) interferometry. Phenomena related to LZS interferometry occur in a variety of physical systems. In particular, recent experiments on LZS interferometry in superconducting TLSs (qubits) have demonstrated the potential for using this kind of interferometry as an effective tool for obtaining the parameters characterizing the TLS as well as its interaction with the control fields and with the environment. Furthermore, strong driving could allow for fast and reliable control of the quantum system. Here we review recent experimental results on LZS interferometry, and we present related theory.

  18. Landau-Zener-Stueckelberg interferometry

    International Nuclear Information System (INIS)

    Shevchenko, S.N.; Ashhab, S.; Nori, Franco

    2010-01-01

    A transition between energy levels at an avoided crossing is known as a Landau-Zener transition. When a two-level system (TLS) is subject to periodic driving with sufficiently large amplitude, a sequence of transitions occurs. The phase accumulated between transitions (commonly known as the Stueckelberg phase) may result in constructive or destructive interference. Accordingly, the physical observables of the system exhibit periodic dependence on the various system parameters. This phenomenon is often referred to as Landau-Zener-Stueckelberg (LZS) interferometry. Phenomena related to LZS interferometry occur in a variety of physical systems. In particular, recent experiments on LZS interferometry in superconducting TLSs (qubits) have demonstrated the potential for using this kind of interferometry as an effective tool for obtaining the parameters characterizing the TLS as well as its interaction with the control fields and with the environment. Furthermore, strong driving could allow for fast and reliable control of the quantum system. Here we review recent experimental results on LZS interferometry, and we present related theory.

  19. Kaon interferometry; Interferometria de kaons

    Energy Technology Data Exchange (ETDEWEB)

    Roldao, C.G.; Padula, S.S. [Instituto de Fisica Teorica (IFT), Sao Paulo, SP (Brazil)

    1994-06-01

    Preliminary results of the {chi}{sup 2} analysis where data on kaon interferometry, obtained from the E859 Collaboration of the AGS/Brookhaven Nat.Lab., are compared with results of a hadronic resonance production model are presented. The main goal is to test the resolution power of the method here discussed when applied to the two-dimensional kaon interferometry. 11 refs., 2 figs.; e-mail: roldao at axp.ift.unesp.br; padula at axp.ift.unesp.br.

  20. Spin dynamics in polarized neutron interferometry

    International Nuclear Information System (INIS)

    Buchelt, R.J.

    2000-05-01

    Since its first implementation in 1974, perfect crystal neutron interferometry has become an extremely successful method applicable to a variety of research fields. Moreover, it proved as an illustrative and didactically valuable experiment for the demonstration of the fundamental principles of quantum mechanics, the neutron being an almost ideal probe for the detection of various effects, as it interacts by all four forces of nature. For instance, the first experimental verification of the 4-pi-periodicity of spinor wave functions was performed with perfect crystal neutron interferometry, and it remains the only method known which demonstrates the quantum mechanical wave-particle-duality of massive particles at a macroscopic separation of the coherent matter waves of several centimeters. A particular position is taken herein by polarized neutron interferometry, which as a collective term comprises all techniques and experiments which not only aim at the coherent splitting and macroscopic separation of neutron beams in the interferometer with the purpose of their separate treatment, but which aim to do so with explicit employment of the spin-magnetic properties of the neutron as a fermion. Remarkable aspects may arise, for example, if nuclear and magnetic potentials are concurrently applied to a partial beam of the interferometer: among other results, it is found that - in perfect agreement to the theoretical predictions - the neutron beam leaving the interferometer features non-zero polarization, even if the incident neutron beam, and hence either of the partial beams, is unpolarized. The main emphasis of the present work lies on the development of an appropriate formalism that describes the effect of simultaneous occurrence of nuclear and magnetic interaction on the emerging intensity and polarization for an arbitrary number of sequential magnetic regions, so-called domains. The confrontation with subtle theoretical problems was inevitable during the experimental

  1. Handbook of Engineering Acoustics

    CERN Document Server

    Möser, Michael

    2013-01-01

    This book examines the physical background of engineering acoustics, focusing on empirically obtained engineering experience as well as on measurement techniques and engineering methods for prognostics. Its goal is not only to describe the state of art of engineering acoustics but also to give practical help to engineers in order to solve acoustic problems. It deals with the origin, the transmission and the methods of the abating different kinds of air-borne and structure-borne sounds caused by various mechanisms – from traffic to machinery and flow-induced sound. In addition the modern aspects of room and building acoustics, as well as psychoacoustics and active noise control, are covered.

  2. Complete positivity and neutron interferometry

    International Nuclear Information System (INIS)

    Benatti, F.; Floreanini, R.

    1999-01-01

    We analyze the dynamics of neutron beams in interferometry experiments using quantum dynamical semigroups. We show that these experiments could provide stringent limits on the non-standard, dissipative terms appearing in the extended evolution equations. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  3. Observations of binary stars by speckle interferometry

    International Nuclear Information System (INIS)

    Morgan, B.L.; Beckmann, G.K.; Scaddan, R.J.

    1980-01-01

    This is the second paper in a series describing observations of binary stars using the technique of speckle interferometry. Observations were made using the 2.5-m Isaac Newton Telescope and the 1-m telescope of the Royal Greenwich Observatory and the 1.9-m telescope of the South African Astronomical Observatory. The classical Rayleigh diffraction limits are 0.050 arcsec for the 2.5-m telescope, 0.065 arcsec for the 1.9-m telescope and 0.125 arcsec for the 1-m telescope, at a wavelength of 500 nm. The results of 29 measurements of 26 objects are presented. The objects include long period spectroscopic binaries from the 6th Catalogue of Batten, close visual binary systems from the 3rd Catalogue of Finsen and Worley and variable stars. Nine of the objects have not been previously resolved by speckle interferometry. New members are detected in the systems β Cep, p Vel and iota UMa. (author)

  4. A computerized system based on an alternative pulse echo immersion technique for acoustic characterization of non-porous solid tissue mimicking materials

    Science.gov (United States)

    Nazihah Mat Daud, Anis; Jaafar, Rosly; Kadri Ayop, Shahrul; Supar Rohani, Md

    2018-04-01

    This paper discusses the development of a computerized acoustic characterization system of non-porous solid tissue mimicking materials. This system employs an alternative pulse echo immersion technique and consists of a pulser/receiver generator, a transducer used as both a transmitter and a receiver, a digital oscilloscope, and a personal computer with a custom-developed program installed. The program was developed on the LabVIEW 2012 platform and comprises two main components, a user interface and a block diagram. The user interface consists of three panels: a signal acquisition and selection panel, a display panel, and a calculation panel. The block diagram comprises four blocks: a signal acquisition block, a peak signal analysis block, an acoustic properties calculation and display block, and an additional block. Interestingly, the system can be operated in both online and offline modes. For the online mode, the measurements are performed by connecting the system with a Rigol DS2000 Series digital oscilloscope. In contrast, the measurements are carried out by processing the saved data on the computer for the offline mode. The accuracy and consistency of the developed system was validated by a KB-Aerotech Alpha Series transducer with 5 MHz center frequency and a Rigol DS2202 two-channel 200 MHz 2 GSa s-1 digital oscilloscope, based on the measurement of the acoustic properties of three poly(methyl methacrylate) samples immersed in a medium at a temperature of (24.0  ±  0.1) °C. The findings indicated that the accuracy and consistency of the developed system was exceptionally high, within a 1.04% margin of error compared to the reference values. As such, this computerized system can be efficiently used for the acoustic characterization of non-porous solid tissues, given its spontaneous display of results, user-friendly interface, and convenient hardware connection.

  5. Architectural acoustics

    National Research Council Canada - National Science Library

    Long, Marshall

    2014-01-01

    .... Beginning with a brief history, it reviews the fundamentals of acoustics, human perception and reaction to sound, acoustic noise measurements, noise metrics, and environmental noise characterization...

  6. Very long baseline interferometry applied to polar motion, relativity, and geodesy. Ph.D. thesis

    International Nuclear Information System (INIS)

    Ma, C.

    1978-01-01

    The causes and effects of diurnal polar motion are described. An algorithm was developed for modeling the effects on very long baseline interferometry observables. A selection was made between two three-station networks for monitoring polar motion. The effects of scheduling and the number of sources observed on estimated baseline errors are discussed. New hardware and software techniques in very long baseline interferometry are described

  7. Acoustic Signals and Systems

    DEFF Research Database (Denmark)

    2008-01-01

    The Handbook of Signal Processing in Acoustics will compile the techniques and applications of signal processing as they are used in the many varied areas of Acoustics. The Handbook will emphasize the interdisciplinary nature of signal processing in acoustics. Each Section of the Handbook...... will present topics on signal processing which are important in a specific area of acoustics. These will be of interest to specialists in these areas because they will be presented from their technical perspective, rather than a generic engineering approach to signal processing. Non-specialists, or specialists...... from different areas, will find the self-contained chapters accessible and will be interested in the similarities and differences between the approaches and techniques used in different areas of acoustics....

  8. Computational Ocean Acoustics

    CERN Document Server

    Jensen, Finn B; Porter, Michael B; Schmidt, Henrik

    2011-01-01

    Since the mid-1970s, the computer has played an increasingly pivotal role in the field of ocean acoustics. Faster and less expensive than actual ocean experiments, and capable of accommodating the full complexity of the acoustic problem, numerical models are now standard research tools in ocean laboratories. The progress made in computational ocean acoustics over the last thirty years is summed up in this authoritative and innovatively illustrated new text. Written by some of the field's pioneers, all Fellows of the Acoustical Society of America, Computational Ocean Acoustics presents the latest numerical techniques for solving the wave equation in heterogeneous fluid–solid media. The authors discuss various computational schemes in detail, emphasizing the importance of theoretical foundations that lead directly to numerical implementations for real ocean environments. To further clarify the presentation, the fundamental propagation features of the techniques are illustrated in color. Computational Ocean A...

  9. Acoustic-Levitation Chamber

    Science.gov (United States)

    Barmatz, M. B.; Granett, D.; Lee, M. C.

    1984-01-01

    Uncontaminated environments for highly-pure material processing provided within completely sealed levitation chamber that suspends particles by acoustic excitation. Technique ideally suited for material processing in low gravity environment of space.

  10. Acoustic Communications Measurement Systems (ACOMMS)

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Design and develop adaptive signal processing techniques to improve underwater acoustic communications and networking. Phase coherent and incoherent signal...

  11. Combination of acoustic levitation with small angle scattering techniques and synchrotron radiation circular dichroism. Application to the study of protein solutions.

    Science.gov (United States)

    Cristiglio, Viviana; Grillo, Isabelle; Fomina, Margarita; Wien, Frank; Shalaev, Evgenyi; Novikov, Alexey; Brassamin, Séverine; Réfrégiers, Matthieu; Pérez, Javier; Hennet, Louis

    2017-01-01

    The acoustic levitation technique is a useful sample handling method for small solid and liquids samples, suspended in air by means of an ultrasonic field. This method was previously used at synchrotron sources for studying pharmaceutical liquids and protein solutions using x-ray diffraction and small angle x-ray scattering (SAXS). In this work we combined for the first time this containerless method with small angle neutron scattering (SANS) and synchrotron radiation circular dichroism (SRCD) to study the structural behavior of proteins in solutions during the water evaporation. SANS results are also compared with SAXS experiments. The aggregation behavior of 45μl droplets of lysozyme protein diluted in water was followed during the continuous increase of the sample concentration by evaporating the solvent. The evaporation kinetics was followed at different drying stage by SANS and SAXS with a good data quality. In a prospective work using SRCD, we also studied the evolution of the secondary structure of the myoglobin protein in water solution in the same evaporation conditions. Acoustic levitation was applied for the first time with SANS and the high performances of the used neutron instruments made it possible to monitor fast container-less reactions in situ. A preliminary work using SRCD shows the potentiality of its combination with acoustic levitation for studying the evolution of the protein structure with time. This multi-techniques approach could give novel insights into crystallization and self-assembly phenomena of biological compound with promising potential applications in pharmaceutical, food and cosmetics industry. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Anal acoustic reflectometry

    DEFF Research Database (Denmark)

    Mitchell, Peter J; Klarskov, Niels; Telford, Karen J

    2011-01-01

    Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis.......Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis....

  13. Precision Geodesy via Radio Interferometry.

    Science.gov (United States)

    Hinteregger, H F; Shapiro, I I; Robertson, D S; Knight, C A; Ergas, R A; Whitney, A R; Rogers, A E; Moran, J M; Clark, T A; Burke, B F

    1972-10-27

    Very-long-baseline interferometry experiments, involving observations of extragalactic radio sources, were performed in 1969 to determine the vector separations between antenna sites in Massachusetts and West Virginia. The 845.130-kilometer baseline was estimated from two separate experiments. The results agreed with each other to within 2 meters in all three components and with a special geodetic survey to within 2 meters in length; the differences in baseline direction as determined by the survey and by interferometry corresponded to discrepancies of about 5 meters. The experiments also yielded positions for nine extragalactic radio sources, most to within 1 arc second, and allowed the hydrogen maser clocks at the two sites to be synchronized a posteriori with an uncertainty of only a few nanoseconds.

  14. Very long baseline interferometry

    International Nuclear Information System (INIS)

    Eckart, A.

    1982-01-01

    In the last few years the resolution of the instruments used in radioastronomy could be enhanced by a factor of 10 000 compared with the human eye. As this method is relatively young and not very well known, the principles of the technique are presented in combination with the most important results. (orig.) [de

  15. Probing of microscale phase-change phenomena based on Michelson interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Sik [Pohang Univ. of Science and Techonology, Pohang (Korea, Republic of); Park, Hee K. [IBM, San Jose (United States); Grigoropoulos, Costas P. [Univ. of California at Berkeley, Berkeley (United States)

    2001-07-01

    Experimental schemes that enable characterization of phase-change phenomena in the microscale regime is essential for understanding the phase-change kinetics. Particularly, monitoring rapid vaporization on a submicron length scale is an important yet challenging task in a variety of laser-processing applications, including steam laser cleaning and liquid-assisted material ablation. This paper introduces a novel technique based on Michelson interferometry for probing the liquid-vaporization process on a solid surface heated by a KrF excimer laser pulse({lambda}=248nm, FWHM=24 ns) in water. The effective thickness of a microbubble layer has been measured with nanosecond time resolution. The maximum bubble size and growth rate are estimated to be of the order of 0.1 {mu}m and 1 m/s, respectively. The results show that the acoustic enhancement in the laser induced vaporization process is caused by bubble expansion in the initial growth stage, not by bubble collapse. This work demonstrates that the interference method is effective for detecting bubble nucleation and microscale vaporization kinetics.

  16. Future Looks Bright for Interferometry

    Science.gov (United States)

    2008-09-01

    First Light for the PRIMA instrument The PRIMA instrument [1] of the ESO Very Large Telescope Interferometer (VLTI) recently saw "first light" at its new home atop Cerro Paranal in Chile. When fully operational, PRIMA will boost the capabilities of the VLTI to see sources much fainter than any previous interferometers, and enable astrometric precision unmatched by any other existing astronomical facility. PRIMA will be a unique tool for the detection of exoplanets. First Light of the PRIMA Instrument ESO PR Photo 29a/08 Preparing for PRIMA "PRIMA is specifically designed to see if one star 'wobbles' to and fro because it is has unseen planetary companions", says instrument scientist Gerard van Belle. "This allows us to not only detect exoplanets, but to measure their mass." PRIMA's expected astrometric precision of tens of micro-arcseconds is unmatched by any other existing astronomical facility, whether on the ground or in orbit [2]. In addition to taking astrometric measurements PRIMA will be the key to the imaging of faint sources with the VLTI using the science instruments AMBER and MIDI. Interferometry combines the light received by two or more telescopes, concentrating on tiny differences between the signals to measure angles with exquisite precision. Using this technique PRIMA can pick out details as sharply as a single telescope with a diameter equivalent to the largest distance between the telescopes. For the VLTI, the distance between the two telescope elements is about 200 metres. The PRIMA instrument is unique amongst the VLTI instruments, in that it is effectively two interferometers in one. PRIMA will take data from two sources on the sky simultaneously: the brighter source can be used for tracking, allowing the interferometer to "stare" at the fainter source for longer than is now possible with conventional interferometers. Although there have been earlier pathfinder experiments to test this technique, PRIMA represents the first facility

  17. Review of Progress in Acoustic Levitation

    Science.gov (United States)

    Andrade, Marco A. B.; Pérez, Nicolás; Adamowski, Julio C.

    2018-04-01

    Acoustic levitation uses acoustic radiation forces to counteract gravity and suspend objects in mid-air. Although acoustic levitation was first demonstrated almost a century ago, for a long time, it was limited to objects much smaller than the acoustic wavelength levitating at fixed positions in space. Recent advances in acoustic levitation now allow not only suspending but also rotating and translating objects in three dimensions. Acoustic levitation is also no longer restricted to small objects and can now be employed to levitate objects larger than the acoustic wavelength. This article reviews the progress of acoustic levitation, focusing on the working mechanism of different types of acoustic levitation devices developed to date. We start with a brief review of the theory. Then, we review the acoustic levitation methods to suspend objects at fixed positions, followed by the techniques that allow the manipulation of objects. Finally, we present a brief summary and offer some future perspectives for acoustic levitation.

  18. Astrophysical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Kitchin, C R

    1984-01-01

    The subject is covered in chapters, entitled: detectors (optical and infrared detection; radio and microwave detection; X-ray and gamma-ray detection; cosmic ray detectors; neutrino detectors; gravitational radiation); imaging (photography; electronic imaging; scanning; interferometry; speckle interferometry; occultations; radar); photometry and photometers; spectroscopy and spectroscopes; other techniques (astrometry; polarimetry; solar studies; magnetometry). Appendices: magnitudes and spectral types of bright stars; north polar sequence; standard stars for the UBV photometric system; standard stars for the UVBY photometric system; standard stars for MK spectral types; standard stars for polarimetry; Julian date; catalogues; answers to the exercises.

  19. Non-invasive thermal profiling of silicon wafer surface during RTP using acoustic and signal processing techniques

    Science.gov (United States)

    Syed, Ahmed Rashid

    Among the great physical challenges faced by the current front-end semiconductor equipment manufacturers is the accurate and repeatable surface temperature measurement of wafers during various fabrication steps. Close monitoring of temperature is essential in that it ensures desirable device characteristics to be reliably reproduced across various wafer lots. No where is the need to control temperature more pronounced than it is during Rapid Thermal Processing (RTP) which involves temperature ramp rates in excess of 200°C/s. This dissertation presents an elegant and practical approach to solve the wafer surface temperature estimation problem, in context of RTP, by deploying hardware that acquires the necessary data while preserving the integrity and purity of the wafer. In contrast to the widely used wafer-contacting (and hence contaminating) methods, such as bonded thermocouples, or environment sensitive schemes, such as light-pipes and infrared pyrometry, the proposed research explores the concept of utilizing Lamb (acoustic) waves to detect changes in wafer surface temperature, during RTP. Acoustic waves are transmitted to the wafer via an array of quartz rods that normally props the wafer inside an RTP chamber. These waves are generated using piezoelectric transducers affixed to the bases of the quartz rods. The group velocity of Lamb waves traversing the wafer surface undergoes a monotonic decrease with rise in wafer temperature. The correspondence of delay in phase of the received Lamb waves and the ambient temperature, along all direct paths between sending and receiving transducers, yields a psuedo real-time thermal image of the wafer. Although the custom built hardware-setup implements the above "proof-of-concept" scheme by transceiving acoustic signals at a single frequency, the real-world application will seek to enhance the data acquistion. rate (>1000 temperature measurements per seconds) by sending and receiving Lamb waves at multiple frequencies (by

  20. Communication Acoustics

    DEFF Research Database (Denmark)

    Blauert, Jens

    Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....

  1. A Study on the Leakage Characteristic Evaluation of High Temperature and Pressure Pipeline at Nuclear Power Plants Using the Acoustic Emission Technique

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Hoon; Kim, Jin Hyun; Song, Bong Min; Lee, Joon Hyun; Cho, Youn Ho [Pusan National University, Busan (Korea, Republic of)

    2009-10-15

    An acoustic leak monitoring system(ALMS) using acoustic emission(AE) technique was applied for leakage detection of nuclear power plant's pipeline which is operated in high temperature and pressure condition. Since this system only monitors the existence of leak using the root mean square(RMS) value of raw signal from AE sensor, the difficulty occurs when the characteristics of leak size and shape need to be evaluated. In this study, dual monitoring system using AE sensor and accelerometer was introduced in order to solve this problem. In addition, artificial neural network(ANN) with Levenberg Marquardt(LM) training algorithm was also applied due to rapid training rate and gave the reliable classification performance. The input parameters of this ANN were extracted from varying signal received from experimental conditions such as the fluid pressure inside pipe, the shape and size of the leak area. Additional experiments were also carried out and with different objective which is to study the generation and characteristic of lamb and surface wave according to the pipe thickness

  2. A Study on the Leakage Characteristic Evaluation of High Temperature and Pressure Pipeline at Nuclear Power Plants Using the Acoustic Emission Technique

    International Nuclear Information System (INIS)

    Kim, Young Hoon; Kim, Jin Hyun; Song, Bong Min; Lee, Joon Hyun; Cho, Youn Ho

    2009-01-01

    An acoustic leak monitoring system(ALMS) using acoustic emission(AE) technique was applied for leakage detection of nuclear power plant's pipeline which is operated in high temperature and pressure condition. Since this system only monitors the existence of leak using the root mean square(RMS) value of raw signal from AE sensor, the difficulty occurs when the characteristics of leak size and shape need to be evaluated. In this study, dual monitoring system using AE sensor and accelerometer was introduced in order to solve this problem. In addition, artificial neural network(ANN) with Levenberg Marquardt(LM) training algorithm was also applied due to rapid training rate and gave the reliable classification performance. The input parameters of this ANN were extracted from varying signal received from experimental conditions such as the fluid pressure inside pipe, the shape and size of the leak area. Additional experiments were also carried out and with different objective which is to study the generation and characteristic of lamb and surface wave according to the pipe thickness

  3. A recent history of science cases for optical interferometry

    Science.gov (United States)

    Defrère, Denis; Aerts, Conny; Kishimoto, Makoto; Léna, Pierre

    2018-04-01

    Optical long-baseline interferometry is a unique and powerful technique for astronomical research. Since the 1980's (with I2T, GI2T, Mark I to III, SUSI, ...), optical interferometers have produced an increasing number of scientific papers covering various fields of astrophysics. As current interferometric facilities are reaching their maturity, we take the opportunity in this paper to summarize the conclusions of a few key meetings, workshops, and conferences dedicated to interferometry. We present the most persistent recommendations related to science cases and discuss some key technological developments required to address them. In the era of extremely large telescopes, optical long-baseline interferometers will remain crucial to probe the smallest spatial scales and make breakthrough discoveries.

  4. X-ray Talbot interferometry with capillary plates

    International Nuclear Information System (INIS)

    Momose, Atsushi; Kawamoto, Shinya

    2006-01-01

    An X-ray Talbot interferometer consisting of two capillary plates, which were used as X-ray amplitude gratings, was evaluated for X-ray phase imaging. A theoretical aspect of capillary X-ray Talbot interferometry is presented with a preliminary operation result using synchrotron radiation. A two-dimensional X-ray Talbot effect, or self-imaging effect, which was the basis of Talbot interferometry, was observed with the capillary plate, and moire images formed by the X-ray Talbot interferometer exhibited contrasts corresponding to the differential phase shift caused by phase objects placed in front of the interferometer. Finally, the possibility of quantitative phase measurement with a fringe scanning technique is discussed. (author)

  5. MAGIA - using atom interferometry to determine the Newtonian gravitational constant

    International Nuclear Information System (INIS)

    Stuhler, J; Fattori, M; Petelski, T; Tino, G M

    2003-01-01

    We describe our experiment MAGIA (misura accurata di G mediante interferometria atomica), in which we will use atom interferometry to perform a high precision measurement of the Newtonian gravitational constant G. Free-falling laser-cooled atoms in a vertical atomic fountain will be accelerated due to the gravitational potential of nearby source masses (SMs). Detecting this acceleration with techniques of Raman atom interferometry will enable us to assign a value to G. To suppress systematic effects we will implement a double-differential measurement. This includes launching two atom clouds in a gradiometer configuration and moving the SMs to different vertical positions. We briefly summarize the general idea of the MAGIA experiment and put it in the context of other high precision G-measurements. We present the current status of the experiment and report on analyses of the expected measurement accuracy

  6. Coupling creep and damage in concrete under high sustained loading: Experimental investigation on bending beams and application of Acoustic Emission technique

    Directory of Open Access Journals (Sweden)

    Grondin F.

    2010-06-01

    had a strengthening 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

  7. Coupling creep and damage in concrete under high sustained loading: Experimental investigation on bending beams and application of Acoustic Emission technique

    Science.gov (United States)

    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

  8. Acoustic Neuroma

    Science.gov (United States)

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

  9. CO2 interferometry

    International Nuclear Information System (INIS)

    Morrison, P.C.

    1978-01-01

    When a machined surface is strained, double-exposure visible holography can be used to detect the change or difference in a profile. However, this technique cannot be used to compare the surface profiles of a master and a production line object, because the unique microstructure of the surfaces is so large that the speckle patterns are uncorrelated. If the radiation wavelength was much larger than the microstructure, then an interferometric comparison between the master and the production object's profiles would be possible. This is the condition for the object surface to behave as a specular reflector and one would only expecct to see the highlights from any single viewing direction. If a suitable diffuser was introduced into the object illumination system, then the whole specular surface could be seen simultaneously. The speckle pattern in the image plane is generated by the unique microstructure of the diffuser. Replacing one specular reflector by a very similar one, will not alter the image plane speckle pattern. A 10.6--μm speckle interferometer has been built with a diffuser placed in the object illumination system. Experimentally, it has been shown that a profile comparison is possible provided the surface roughness of the objects is less than 20/25 μin. (CLA). Unfortunately the spatial resolution of the detector was worse than expected. This is a major problem which has not been solved

  10. Damage monitoring in historical murals by speckle interferometry

    Science.gov (United States)

    Hinsch, Klaus D.; Gulker, Gerd; Joost, Holger

    2003-11-01

    In the conservation of historical murals it is important to identify loose plaster sections that threaten to fall off. Electronic speckle interferometry in combination with acoustic excitation of the object has been employed to monitor loose areas. To avoid disadvantages of high sound irradiation of the complete building a novel directional audio-sound source based on nonlinear mixing of ultrasound has been introduced. The optical system was revised for optimum performance in the new environment. Emphasis is placed on noise suppression to increase sensitivity. Furthermore, amplitude and phase data of object response over the frequency-range inspected are employed to gain additional information on the state of the plaster or paint. Laboratory studies on sample specimen supplement field campaigns at historical sites.

  11. Acoustic remote sensing of ocean flows

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Desa, E.

    Acoustic techniques have become powerful tools for measurement of ocean circulation mainly because of the ability of acoustic signals to travel long distances in water, and the inherently non-invasive nature of measurement. The satellite remote...

  12. Attosecond electron wave packet interferometry

    International Nuclear Information System (INIS)

    Remetter, T.; Ruchon, T.; Johnsson, P.; Varju, K.; Gustafsson, E.

    2006-01-01

    Complete test of publication follows. The well controlled generation and characterization of attosecond XUV light pulses provide an unprecedented tool to study electron wave packets (EWPs). Here a train of attosecond pulses is used to create and study the phase of an EWP in momentum space. There is a clear analogy between electronic wave functions and optical fields. In optics, methods like SPIDER or wave front shearing interferometry, allow to measure the spectral or spatial phase of a light wave. These two methods are based on the same principle: an interferogram is produced when recombining two sheared replica of a light pulse, spectrally (SPIDER) or spatially (wave front shearing interferometry). This enables the comparison of two neighbouring different spectral or spatial slices of the original wave packet. In the experiment, a train of attosecond pulses is focused in an Argon atomic gas jet. EWPs are produced from the single XUV photon ionization of Argon atoms. If an IR beam is synchronized to the EWPs, it is possible to introduce a shear in momentum space between two consecutive s wave packets. A Velocity Map Imaging Spectrometer (VMIS) enables us to detect the interference pattern. An analysis of the interferograms will be presented leading to a conclusion about the symmetry of the studied wave packet.

  13. Mapping small elevation changes over large areas - Differential radar interferometry

    Science.gov (United States)

    Gabriel, Andrew K.; Goldstein, Richard M.; Zebker, Howard A.

    1989-01-01

    A technique is described, based on synthetic aperture radar (SAR) interferometry, which uses SAR images for measuring very small (1 cm or less) surface motions with good resolution (10 m) over swaths of up to 50 km. The method was applied to a Seasat data set of an imaging site in Imperial Valley, California, where motion effects were observed that were identified with movements due to the expansion of water-absorbing clays. The technique can be used for accurate measurements of many geophysical phenomena, including swelling and buckling in fault zones, residual displacements from seismic events, and prevolcanic swelling.

  14. Neutron Interferometry at the National Institute of Standards and Technology

    International Nuclear Information System (INIS)

    Huber, M. G.; Sarenac, D.; Nsofini, J.; Pushin, D. A.; Arif, M.; Wood, C. J.; Cory, D. G.; Shahi, C. B.

    2015-01-01

    Neutron interferometry has proved to be a very precise technique for measuring the quantum mechanical phase of a neutron caused by a potential energy difference between two spatially separated neutron paths inside interferometer. The path length inside the interferometer can be many centimeters (and many centimeters apart) making it very practical to study a variety of samples, fields, potentials, and other macroscopic medium and quantum effects. The precision of neutron interferometry comes at a cost; neutron interferometers are very susceptible to environmental noise that is typically mitigated with large, active isolated enclosures. With recent advances in quantum information processing especially quantum error correction (QEC) codes we were able to demonstrate a neutron interferometer that is insensitive to vibrational noise. A facility at NIST’s Center for Neutron Research (NCNR) has just been commissioned with higher neutron flux than the NCNR’s older interferometer setup. This new facility is based on QEC neutron interferometer, thus improving the accessibility of neutron interferometry to the greater scientific community and expanding its applications to quantum computing, gravity, and material research

  15. Experimental demonstration of deep frequency modulation interferometry.

    Science.gov (United States)

    Isleif, Katharina-Sophie; Gerberding, Oliver; Schwarze, Thomas S; Mehmet, Moritz; Heinzel, Gerhard; Cervantes, Felipe Guzmán

    2016-01-25

    Experiments for space and ground-based gravitational wave detectors often require a large dynamic range interferometric position readout of test masses with 1 pm/√Hz precision over long time scales. Heterodyne interferometer schemes that achieve such precisions are available, but they require complex optical set-ups, limiting their scalability for multiple channels. This article presents the first experimental results on deep frequency modulation interferometry, a new technique that combines sinusoidal laser frequency modulation in unequal arm length interferometers with a non-linear fit algorithm. We have tested the technique in a Michelson and a Mach-Zehnder Interferometer topology, respectively, demonstrated continuous phase tracking of a moving mirror and achieved a performance equivalent to a displacement sensitivity of 250 pm/Hz at 1 mHz between the phase measurements of two photodetectors monitoring the same optical signal. By performing time series fitting of the extracted interference signals, we measured that the linearity of the laser frequency modulation is on the order of 2% for the laser source used.

  16. Geometric phase modulation for stellar interferometry

    International Nuclear Information System (INIS)

    Roy, M.; Boschung, B.; Tango, W.J.; Davis, J.

    2002-01-01

    Full text: In a long baseline optical interferometer, the fringe visibility is normally measured by modulation of the optical path difference between the two arms of the instruments. To obtain accurate measurements, the spectral bandwidth must be narrow, limiting the sensitivity of the technique. The application of geometric phase modulation technique to stellar interferometry has been proposed by Tango and Davis. Modulation of the geometric phase has the potential for improving the sensitivity of optical interferometers, and specially the Sydney University Stellar Interferometer (SUSI), by allowing broad band modulation of the light signals. This is because a modulator that changes the geometric phase of the signal is, in principle, achromatic. Another advantage of using such a phase modulator is that it can be placed in the common path traversed by the two orthogonally polarized beams emerging from the beam combiner in a stellar interferometer. Thus the optical components of the modulator do not have to be interferometric quality and could be relatively easily introduced into SUSI. We have investigated the proposed application in a laboratory-based experiment using a Mach-Zehnder interferometer with white-light source. This can be seen as a small model of an amplitude stellar interferometer where the light source takes the place of the distant star and two corner mirrors replaces the entrance pupils of the stellar interferometer

  17. Using Seismic Interferometry to Investigate Seismic Swarms

    Science.gov (United States)

    Matzel, E.; Morency, C.; Templeton, D. C.

    2017-12-01

    Seismicity provides a direct means of measuring the physical characteristics of active tectonic features such as fault zones. Hundreds of small earthquakes often occur along a fault during a seismic swarm. This seismicity helps define the tectonically active region. When processed using novel geophysical techniques, we can isolate the energy sensitive to the fault, itself. Here we focus on two methods of seismic interferometry, ambient noise correlation (ANC) and the virtual seismometer method (VSM). ANC is based on the observation that the Earth's background noise includes coherent energy, which can be recovered by observing over long time periods and allowing the incoherent energy to cancel out. The cross correlation of ambient noise between a pair of stations results in a waveform that is identical to the seismogram that would result if an impulsive source located at one of the stations was recorded at the other, the Green function (GF). The calculation of the GF is often stable after a few weeks of continuous data correlation, any perturbations to the GF after that point are directly related to changes in the subsurface and can be used for 4D monitoring.VSM is a style of seismic interferometry that provides fast, precise, high frequency estimates of the Green's function (GF) between earthquakes. VSM illuminates the subsurface precisely where the pressures are changing and has the potential to image the evolution of seismicity over time, including changes in the style of faulting. With hundreds of earthquakes, we can calculate thousands of waveforms. At the same time, VSM collapses the computational domain, often by 2-3 orders of magnitude. This allows us to do high frequency 3D modeling in the fault region. Using data from a swarm of earthquakes near the Salton Sea, we demonstrate the power of these techniques, illustrating our ability to scale from the far field, where sources are well separated, to the near field where their locations fall within each other

  18. Developing Wide-Field Spatio-Spectral Interferometry for Far-Infrared Space Applications

    Science.gov (United States)

    Leisawitz, David; Bolcar, Matthew R.; Lyon, Richard G.; Maher, Stephen F.; Memarsadeghi, Nargess; Rinehart, Stephen A.; Sinukoff, Evan J.

    2012-01-01

    Interferometry is an affordable way to bring the benefits of high resolution to space far-IR astrophysics. We summarize an ongoing effort to develop and learn the practical limitations of an interferometric technique that will enable the acquisition of high-resolution far-IR integral field spectroscopic data with a single instrument in a future space-based interferometer. This technique was central to the Space Infrared Interferometric Telescope (SPIRIT) and Submillimeter Probe of the Evolution of Cosmic Structure (SPECS) space mission design concepts, and it will first be used on the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII). Our experimental approach combines data from a laboratory optical interferometer (the Wide-field Imaging Interferometry Testbed, WIIT), computational optical system modeling, and spatio-spectral synthesis algorithm development. We summarize recent experimental results and future plans.

  19. Application of deconvolution interferometry with both Hi-net and KiK-net data

    Science.gov (United States)

    Nakata, N.

    2013-12-01

    Application of deconvolution interferometry to wavefields observed by KiK-net, a strong-motion recording network in Japan, is useful for estimating wave velocities and S-wave splitting in the near surface. Using this technique, for example, Nakata and Snieder (2011, 2012) found changed in velocities caused by Tohoku-Oki earthquake in Japan. At the location of the borehole accelerometer of each KiK-net station, a velocity sensor is also installed as a part of a high-sensitivity seismograph network (Hi-net). I present a technique that uses both Hi-net and KiK-net records for computing deconvolution interferometry. The deconvolved waveform obtained from the combination of Hi-net and KiK-net data is similar to the waveform computed from KiK-net data only, which indicates that one can use Hi-net wavefields for deconvolution interferometry. Because Hi-net records have a high signal-to-noise ratio (S/N) and high dynamic resolution, the S/N and the quality of amplitude and phase of deconvolved waveforms can be improved with Hi-net data. These advantages are especially important for short-time moving-window seismic interferometry and deconvolution interferometry using later coda waves.

  20. Debonding damage analysis in composite-masonry strengthening systems with polymer- and mortar-based matrix by means of the acoustic emission technique

    International Nuclear Information System (INIS)

    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. (paper)

  1. High speed digital holographic interferometry for hypersonic flow visualization

    Science.gov (United States)

    Hegde, G. M.; Jagdeesh, G.; Reddy, K. P. J.

    2013-06-01

    Optical imaging techniques have played a major role in understanding the flow dynamics of varieties of fluid flows, particularly in the study of hypersonic flows. Schlieren and shadowgraph techniques have been the flow diagnostic tools for the investigation of compressible flows since more than a century. However these techniques provide only the qualitative information about the flow field. Other optical techniques such as holographic interferometry and laser induced fluorescence (LIF) have been used extensively for extracting quantitative information about the high speed flows. In this paper we present the application of digital holographic interferometry (DHI) technique integrated with short duration hypersonic shock tunnel facility having 1 ms test time, for quantitative flow visualization. Dynamics of the flow fields in hypersonic/supersonic speeds around different test models is visualized with DHI using a high-speed digital camera (0.2 million fps). These visualization results are compared with schlieren visualization and CFD simulation results. Fringe analysis is carried out to estimate the density of the flow field.

  2. Space Interferometry Mission Instrument Mechanical Layout

    Science.gov (United States)

    Aaron, K.; Stubbs, D.; Kroening, K.

    2000-01-01

    The Space Interferometry Mission, planned for launch in 2006, will measure the positions of celestial objects to an unprecedented accuracy of 4x10 to the power of negative six arc (about 1 billionth of a degree).

  3. Some applications of holographic interferometry in biomechanics

    Science.gov (United States)

    Ebbeni, Jean P. L.

    1992-03-01

    Holographic interferometry is well adapted for the determination of 2D strain fields in osseous structures. The knowledge of those strain fields is important for the understanding of structure behavior such as arthrosis.

  4. Interferometry of high energy nuclear collisions

    International Nuclear Information System (INIS)

    Padula, S.S.

    1990-01-01

    The interferometry is used for determining large space time dimensions of the Quark Gluon Plasma formed in high energy nuclear collisions or in high multiplicity fluctuations in p-barp collisions. (M.C.K.)

  5. Analytic approximations for inside-outside interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Padula, S.S.; Gyulassy, M. (Lawrence Berkeley Lab., CA (USA). Nuclear Science Div.)

    1990-07-30

    Analytical expressions for pion interferometry are derived illustrating the competing effects of various non-ideal aspects of inside-outside cascade dynamics at energies {proportional to}200 AGeV. (orig.).

  6. Topological Acoustics

    Science.gov (United States)

    Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

    2015-03-01

    The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.

  7. Acoustical Imaging

    CERN Document Server

    Litniewski, Jerzy; Kujawska, Tamara; 31st International Symposium on Acoustical Imaging

    2012-01-01

    The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place continuously since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2011 the 31st International Symposium on Acoustical Imaging was held in Warsaw, Poland, April 10-13. Offering both a broad perspective on the state-of-the-art as well as  in-depth research contributions by the specialists in the field, this Volume 31 in the Series contains an excellent collection of papers in six major categories: Biological and Medical Imaging Physics and Mathematics of Acoustical Imaging Acoustic Microscopy Transducers and Arrays Nondestructive Evaluation and Industrial Applications Underwater Imaging

  8. Complex Interaction Mechanisms between Dislocations and Point Defects Studied in Pure Aluminium by a Two-Wave Acoustic Coupling Technique

    Science.gov (United States)

    Bremnes, O.; Progin, O.; Gremaud, G.; Benoit, W.

    1997-04-01

    Ultrasonic experiments using a two-wave coupling technique were performed on 99.999% pure Al in order to study the interaction mechanisms occurring between dislocations and point defects. The coupling technique consists in measuring the attenuation of ultrasonic waves during low-frequency stress cycles (t). One obtains closed curves () called signatures whose shape and evolution are characteristic of the interaction mechanism controlling the low-frequency dislocation motion. The signatures observed were attributed to the interaction of the dislocations with extrinsic point defects. A new interpretation of the evolution of the signatures measured below 200 K with respect to temperature and stress frequency had to be established: they are linked to depinning of immobile point defects, whereas a thermally activated depinning mechanism does not fit the observations. The signatures measured between 200 and 370 K were interpreted as dragging and depinning of extrinsic point defects which are increasingly mobile with temperature.

  9. Acoustic textiles

    CERN Document Server

    Nayak, Rajkishore

    2016-01-01

    This book highlights the manufacturing and applications of acoustic textiles in various industries. It also includes examples from different industries in which acoustic textiles can be used to absorb noise and help reduce the impact of noise at the workplace. Given the importance of noise reduction in the working environment in several industries, the book offers a valuable guide for companies, educators and researchers involved with acoustic materials.

  10. Time delay interferometry with moving spacecraft arrays

    International Nuclear Information System (INIS)

    Tinto, Massimo; Estabrook, F.B.; Armstrong, J.W.

    2004-01-01

    Space-borne interferometric gravitational wave detectors, sensitive in the low-frequency (millihertz) band, will fly in the next decade. In these detectors the spacecraft-to-spacecraft light-travel-times will necessarily be unequal, time varying, and (due to aberration) have different time delays on up and down links. The reduction of data from moving interferometric laser arrays in solar orbit will in fact encounter nonsymmetric up- and down-link light time differences that are about 100 times larger than has previously been recognized. The time-delay interferometry (TDI) technique uses knowledge of these delays to cancel the otherwise dominant laser phase noise and yields a variety of data combinations sensitive to gravitational waves. Under the assumption that the (different) up- and down-link time delays are constant, we derive the TDI expressions for those combinations that rely only on four interspacecraft phase measurements. We then turn to the general problem that encompasses time dependence of the light-travel times along the laser links. By introducing a set of noncommuting time-delay operators, we show that there exists a quite general procedure for deriving generalized TDI combinations that account for the effects of time dependence of the arms. By applying our approach we are able to re-derive the 'flex-free' expression for the unequal-arm Michelson combinations X 1 , and obtain the generalized expressions for the TDI combinations called relay, beacon, monitor, and symmetric Sagnac

  11. 2. Interferometry and polarimetry. 2.1. Principle of interferometry and polarimetry

    International Nuclear Information System (INIS)

    Kawahata, Kazuo; Okajima, Shigeki

    2000-01-01

    Laser interferometry and polarimetry are useful diagnostics for measuring electron density and the internal magnetic field distribution in the plasma. In this section, principles of interferometry and polarimetry and their applications to plasma diagnostics on LHD (section 2.2) and JT-60 (section 2.3) are descried. (author)

  12. IMAP: Interferometry for Material Property Measurement in MEMS

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, B.D.; Miller, S.L.; de Boer, M.P.

    1999-03-10

    An interferometric technique has been developed for non-destructive, high-confidence, in-situ determination of material properties in MEMS. By using interferometry to measure the full deflection curves of beams pulled toward the substrate under electrostatic loads, the actual behavior of the beams has been modeled. No other method for determining material properties allows such detailed knowledge of device behavior to be gathered. Values for material properties and non-idealities (such as support post compliance) have then been extracted which minimize the error between the measured and modeled deflections. High accuracy and resolution have been demonstrated, allowing the measurements to be used to enhance process control.

  13. Modelling of a holographic interferometry based calorimeter for radiation dosimetry

    Science.gov (United States)

    Beigzadeh, A. M.; Vaziri, M. R. Rashidian; Ziaie, F.

    2017-08-01

    In this research work, a model for predicting the behaviour of holographic interferometry based calorimeters for radiation dosimetry is introduced. Using this technique for radiation dosimetry via measuring the variations of refractive index due to energy deposition of radiation has several considerable advantages such as extreme sensitivity and ability of working without normally used temperature sensors that disturb the radiation field. We have shown that the results of our model are in good agreement with the experiments performed by other researchers under the same conditions. This model also reveals that these types of calorimeters have the additional and considerable merits of transforming the dose distribution to a set of discernible interference fringes.

  14. Model-based multi-fringe interferometry using Zernike polynomials

    Science.gov (United States)

    Gu, Wei; Song, Weihong; Wu, Gaofeng; Quan, Haiyang; Wu, Yongqian; Zhao, Wenchuan

    2018-06-01

    In this paper, a general phase retrieval method is proposed, which is based on one single interferogram with a small amount of fringes (either tilt or power). Zernike polynomials are used to characterize the phase to be measured; the phase distribution is reconstructed by a non-linear least squares method. Experiments show that the proposed method can obtain satisfactory results compared to the standard phase-shifting interferometry technique. Additionally, the retrace errors of proposed method can be neglected because of the few fringes; it does not need any auxiliary phase shifting facilities (low cost) and it is easy to implement without the process of phase unwrapping.

  15. From linear optical quantum computing to Heisenberg-limited interferometry

    International Nuclear Information System (INIS)

    Lee, Hwang; Kok, Pieter; Williams, Colin P; Dowling, Jonathan P

    2004-01-01

    The working principles of linear optical quantum computing are based on photodetection, namely, projective measurements. The use of photodetection can provide efficient nonlinear interactions between photons at the single-photon level, which is technically problematic otherwise. We report an application of such a technique to prepare quantum correlations as an important resource for Heisenberg-limited optical interferometry, where the sensitivity of phase measurements can be improved beyond the usual shot-noise limit. Furthermore, using such nonlinearities, optical quantum non-demolition measurements can now be carried out easily at the single-photon level

  16. Contribution of the Acoustic Emission technique in the understanding and the modelling of the coupling between creep and damage in concrete

    International Nuclear Information System (INIS)

    Saliba, J.

    2012-01-01

    In order to design reliable concrete structures, prediction of long term behaviour of concrete is important. In fact, creep deformation can cause mechanical deterioration and cracking, stress redistribution, loss in prestressed members and rarely ruin the structure. The aim of this research is to have a better understanding of the interaction between creep and crack growth in concrete. An experimental investigation on the fracture properties of concrete beams submitted to creep bending tests with high levels of sustained load is reported. The influence of creep on residual capacity and fracture energy of concrete is studied. In parallel, the acoustic emission technique (AE) was used to monitor crack development. The results give wealth information on damage evolution and show a decrease in the width of the fracture process zone (FPZ) characterizing a more brittle behaviour for beams subjected to creep. The AE shows that this may be due to the development of microcracking detected under creep. Based on those experimental results, a mesoscopic numerical study was proposed by coupling a damage model based on the micro-plan theory and a viscoelastic creep model defined by several Kelvin-voigt chains. The numerical results on concrete specimens in tension and in bending confirm the development of microcracks during creep at the mortar-aggregate interface. (author)

  17. Use of acoustic emission technique to study the spalling behaviour of oxide scales on Ni-10Cr-8Al containing sulphur and/or yttrium impurity

    International Nuclear Information System (INIS)

    Khanna, A.S.; Quadakkers, W.J.; Jonas, H.

    1989-01-01

    It is now well established that the presence of small amounts of sulphur impurity in a NiCrAl-based alloy causes a deleterious effect on their high temperature oxidation behaviour. It is, however, not clear whether the adverse effect is due to a decrease in the spalling resistance of the oxide scale or due to an enhanced scale growth. In order to confirm which of the factors is dominating, two independent experimental techniques were used in the investigation of the oxidation behaviour of Ni-10Cr-8Al containing sulphur- and/or yttrium additions: conventional thermogravimetry, to study the scale growth rates and acoustic emission analysis to study the scale adherence. The results indicated that the dominant factor responsible for the deleterious effect of sulphur impurity on the oxidation of a Ni-10Cr-8Al alloy, was a significant change in the growth rate and the composition of the scale. Addition of yttrium improved the oxidation behaviour, not only by increasing the scale adherence, but also by reducing the scale growth due to gettering of sulphur. (orig.) [de

  18. Self-Sensing of Single Carbon Fiber/Carbon Nanotube-Epoxy Composites Using Electro-Micromechanical Techniques and Acoustic Emission

    International Nuclear Information System (INIS)

    Park, Joung Man; Jang, Jung Hoon; Wang, Zuo Jia; Kwon, Dong Jun; Park, Jong Kyu; Lee, Woo Il

    2010-01-01

    Self-sensing on micro-failure, dispersion degree and relating properties, of carbon nanotube(CNT)/epoxy composites, were investigated using wettability, electro-micromechanical technique with acoustic emission(AE). Specimens were prepared from neat epoxy as well as composites with untreated and acid-treated CNT. Degree of dispersion was evaluated comparatively by measuring volumetric electrical resistivity and its standard deviation. Apparent modulus containing the stress transfer was higher for acid-treated CNT composite than for the untreated case. Applied cyclic loading responded well for a single carbon fiber/CNT-epoxy composite by the change in contact resistivity. The interfacial shear strength between a single carbon fiber and CNT-epoxy, determined in a fiber pullout test, was lower than that between a single carbon fiber and neat epoxy. Regarding on micro-damage sensing using electrical resistivity measurement with AE, the stepwise increment in electrical resistivity was observed for a single carbon fiber/CNT-epoxy composite. On the other hand, electrical resistivity increased infinitely right after the first carbon fiber breaks for a single carbon fiber/neat epoxy composite. The occurrence of AE events of added CNT composites was much higher than the neat epoxy case, due to microfailure at the interfaces by added CNTs

  19. Visualization investigation of acoustic and flow-induced vibration in main stream lines using a high-time-resolved PIV technique

    International Nuclear Information System (INIS)

    Li, Yanrong; Someya, Satoshi; Okamoto, Koji

    2009-01-01

    Systems with closed side-branches are liable to an excitation of sound, as called cavity tone. It may occur in pipe branches leading to safety valves or to boiler relief valves. The outbreak mechanism of the cavity tone has been known by phase-averaged measurement in previous researches, while the relation between sound propagation and flow field is still unclear due to the difficulty of detecting instantaneous velocity field. High-time-resolved PIV has a possibility to analyze the velocity field and the relation mentioned above. In this study, flow-induced acoustic resonance of piping system containing closed side-branches was investigated experimentally. A high-time-resolved PIV technique was applied to measure a gas-flow in a cavity. Air flow containing oil mist as tracer particles was measured using a high frequency pulse laser and a high speed camera. The present investigation on the coaxial closed side-branches is the first rudimentary study to visualize the fluid flow two-dimensionally in the cross-section by using PIV and to measure the pressure at the downstream side opening of the cavity by microphone. The fluid flows at different points in the cavity interact with some phase differences and the relation was clarified. (author)

  20. Acoustic Emission Technology and Application

    International Nuclear Information System (INIS)

    Joo, Y. S.; Lim, S. H.; Eom, H. S.; Kim, J. H.; Jung, H. K.

    2003-10-01

    Acoustic emission is the elastic wave that is generated by the rapid release of energy from the localized sources within a material. After the observation of acoustic emission phenomenon in 1950, the research and further investigation had been performed. Acoustic emission examination becomes a rapidly matured nondestructive testing method with demonstrated capabilities for characterizing material behavior and for detecting the defect. It is of interest as a possible passive monitoring technique for detecting, locating and characterizing the defects in component and structure. Acoustic emission technology has recently strengthened the on-line monitoring application for the detection of incipient failures and the assurance of structural integrity. The field of acoustic emission testing is still growing vigorously and presents many challenges. Especially, acoustic emission has been successfully applied in the leak detection of primary pressure boundary of nuclear power plants. In this state-of-art report, the principle, measurement and field applications of acoustic emission technique is reviewed and summarized. Acoustic emission technology will contribute to the assurance of nuclear safety as the on-line monitoring technique of structural integrity of NSSS components and structures

  1. Electronic speckle pattern interferometry observation of brick–mortar interface behaviour under compression

    NARCIS (Netherlands)

    Vermeltfoort, A.T.; Martens, D.R.W; Zijl, van G.P.A.G.

    2007-01-01

    The brick–mortar interaction is important in the mechanical behaviour of masonry. It affects the load transfer considerably, as shown by detailed deformation measurements taken using electronic speckle pattern interferometry (ESPI), a laser speckle interference technique. A companion paper [Canadian

  2. Monitoring Line-Infrastructure With Multisensor SAR Interferometry : Products and Performance Assessment Metrics

    NARCIS (Netherlands)

    Chang, L.; Dollevoet, R.P.B.J.; Hanssen, R.F.

    2018-01-01

    Satellite radar interferometry (InSAR) is an emerging technique to monitor the stability and health of line-infrastructure assets, such as railways, dams, and pipelines. However, InSAR is an opportunistic approach as the location and occurrence of its measurements (coherent scatterers) cannot be

  3. A portable magneto-optical trap with prospects for atom interferometry in civil engineering

    Science.gov (United States)

    Hinton, A.; Perea-Ortiz, M.; Winch, J.; Briggs, J.; Freer, S.; Moustoukas, D.; Powell-Gill, S.; Squire, C.; Lamb, A.; Rammeloo, C.; Stray, B.; Voulazeris, G.; Zhu, L.; Kaushik, A.; Lien, Y.-H.; Niggebaum, A.; Rodgers, A.; Stabrawa, A.; Boddice, D.; Plant, S. R.; Tuckwell, G. W.; Bongs, K.; Metje, N.; Holynski, M.

    2017-06-01

    The high precision and scalable technology offered by atom interferometry has the opportunity to profoundly affect gravity surveys, enabling the detection of features of either smaller size or greater depth. While such systems are already starting to enter into the commercial market, significant reductions are required in order to reach the size, weight and power of conventional devices. In this article, the potential for atom interferometry based gravimetry is assessed, suggesting that the key opportunity resides within the development of gravity gradiometry sensors to enable drastic improvements in measurement time. To push forward in realizing more compact systems, techniques have been pursued to realize a highly portable magneto-optical trap system, which represents the core package of an atom interferometry system. This can create clouds of 107 atoms within a system package of 20 l and 10 kg, consuming 80 W of power. This article is part of the themed issue 'Quantum technology for the 21st century'.

  4. Theory of supervirtual refraction interferometry

    KAUST Repository

    Bharadwaj, Pawan; Schuster, Gerard T.; Mallinson, Ian; Dai, Wei

    2012-01-01

    Inverting for the subsurface velocity distribution by refraction traveltime tomography is a well-accepted imaging method by both the exploration and earthquake seismology communities. A significant drawback, however, is that the recorded traces become noisier with increasing offset from the source position, and so accurate picking of traveltimes in far-offset traces is often prevented. To enhance the signal-to-noise ratio (SNR) of the far-offset traces, we present the theory of supervirtual refraction interferometry where the SNR of far-offset head-wave arrivals can be theoretically increased by a factor proportional to; here, N is the number of receiver or source positions associated with the recording and generation of the head-wave arrival. There are two steps to this methodology: correlation and summation of the data to generate traces with virtual head-wave arrivals, followed by the convolution of the data with the virtual traces to create traces with supervirtual head-wave arrivals. This method is valid for any medium that generates head-wave arrivals recorded by the geophones. Results with both synthetic traces and field data demonstrate the feasibility of this method. There are at least four significant benefits of supervirtual interferometry: (1) an enhanced SNR of far-offset traces so the first-arrival traveltimes of the noisy far-offset traces can be more reliably picked to extend the useful aperture of the data, (2) the SNR of head waves in a trace that arrive later than the first arrival can be enhanced for accurate traveltime picking and subsequent inversion by later-arrival traveltime tomography, (3) common receiver-pair gathers can be analysed to detect the presence of diving waves in the first arrivals, which can be used to assess the nature of the refracting boundary, and (4) the source statics term is eliminated in the correlation operations so that the timing of the virtual traces is independent of the source excitation time. This suggests the

  5. Vegetation Parameter Extraction Using Dual Baseline Polarimetric SAR Interferometry Data

    Science.gov (United States)

    Zhang, H.; Wang, C.; Chen, X.; Tang, Y.

    2009-04-01

    For vegetation parameter inversion, the single baseline polarimetric SAR interferometry (POLinSAR) technique, such as the three-stage method and the ESPRIT algorithm, is limited by the observed data with the minimum ground to volume amplitude ration, which effects the estimation of the effective phase center for the vegetation canopy or the surface, and thus results in the underestimated vegetation height. In order to remove this effect of the single baseline inversion techniques in some extend, another baseline POLinSAR data is added on vegetation parameter estimation in this paper, and a dual baseline POLinSAR technique for the extraction of the vegetation parameter is investigated and improved to reduce the dynamic bias for the vegetation parameter estimation. Finally, the simulated data and real data are used to validate this dual baseline technique.

  6. Algorithms and Array Design Criteria for Robust Imaging in Interferometry

    Science.gov (United States)

    Kurien, Binoy George

    Optical interferometry is a technique for obtaining high-resolution imagery of a distant target by interfering light from multiple telescopes. Image restoration from interferometric measurements poses a unique set of challenges. The first challenge is that the measurement set provides only a sparse-sampling of the object's Fourier Transform and hence image formation from these measurements is an inherently ill-posed inverse problem. Secondly, atmospheric turbulence causes severe distortion of the phase of the Fourier samples. We develop array design conditions for unique Fourier phase recovery, as well as a comprehensive algorithmic framework based on the notion of redundant-spaced-calibration (RSC), which together achieve reliable image reconstruction in spite of these challenges. Within this framework, we see that classical interferometric observables such as the bispectrum and closure phase can limit sensitivity, and that generalized notions of these observables can improve both theoretical and empirical performance. Our framework leverages techniques from lattice theory to resolve integer phase ambiguities in the interferometric phase measurements, and from graph theory, to select a reliable set of generalized observables. We analyze the expected shot-noise-limited performance of our algorithm for both pairwise and Fizeau interferometric architectures and corroborate this analysis with simulation results. We apply techniques from the field of compressed sensing to perform image reconstruction from the estimates of the object's Fourier coefficients. The end result is a comprehensive strategy to achieve well-posed and easily-predictable reconstruction performance in optical interferometry.

  7. Investigations on flexural wave propagation and attenuation in a modified one-dimensional acoustic black hole using a laser excitation technique

    Science.gov (United States)

    Ji, Hongli; Luo, Jing; Qiu, Jinhao; Cheng, Li

    2018-05-01

    Acoustic Black Holes (ABHs), as a new type of passive structure for vibration damping enhancement and noise attenuation, have been drawing increasing attentions of many researchers. Due to the difficulty in manufacturing the sharp edges required by the ABH structures, it is important to understand the wave propagation and attenuation process in the presence of damping layers in non-ideal ABHs with a truncated edge. In this paper, an analytical expression of the wave reflection coefficient in a modified one-dimensional ABH is derived and a time-domain experimental method based on a laser excitation technique is used to visualize the wave propagation. In the experimental studies, the flexural waves in the ABH were excited by a scanning pulse laser and measured by a Laser Doppler Vibrometer (LDV). The incident wave and reflected wave were separated from the measured original wave field and the decrease of the wave velocity in the ABH was exhibited. The reflection coefficient was calculated from the ratio of the amplitude of the reflected wave to that of the incident wave for different ABH parameters and different thicknesses of the damping layer. The measured reflection coefficients were used to identify the unknown coefficients in the theoretical formula. The results confirm that there exists an optimal thickness for the damping layer, which leads to the minimum wave reflection. Based on the laser-induced visualization technique and various signal processing and feature extraction methods, the entire process of the wave propagation in a non-ideal one-dimensional ABH structure can be visualized and scrutinized.

  8. Portable acoustic myography

    DEFF Research Database (Denmark)

    Harrison, Adrian Paul; Danneskiold-Samsøe, Bente; Bartels, Else Marie

    2013-01-01

    Muscle sound gives a local picture of muscles involved in a particular movement and is independent of electrical signals between nerve and muscle. Sound recording (acoustic myography) is a well-known noninvasive technique that has suffered from not being easily applicable, as well as not being able...

  9. Parsimonious Refraction Interferometry and Tomography

    KAUST Repository

    Hanafy, Sherif

    2017-02-04

    We present parsimonious refraction interferometry and tomography where a densely populated refraction data set can be obtained from two reciprocal and several infill shot gathers. The assumptions are that the refraction arrivals are head waves, and a pair of reciprocal shot gathers and several infill shot gathers are recorded over the line of interest. Refraction traveltimes from these shot gathers are picked and spawned into O(N2) virtual refraction traveltimes generated by N virtual sources, where N is the number of geophones in the 2D survey. The virtual traveltimes can be inverted to give the velocity tomogram. This enormous increase in the number of traveltime picks and associated rays, compared to the many fewer traveltimes from the reciprocal and infill shot gathers, allows for increased model resolution and a better condition number with the system of normal equations. A significant benefit is that the parsimonious survey and the associated traveltime picking is far less time consuming than that for a standard refraction survey with a dense distribution of sources.

  10. Self-mixing interferometry: a novel yardstick for mechanical metrology

    Science.gov (United States)

    Donati, Silvano

    2016-11-01

    A novel configuration of interferometry, SMI (self-mixing interferometry), is described in this paper. SMI is attractive because it doesn't require any optical part external to the laser and can be employed in a variety of measurements - indeed it is sometimes indicated as the "interferometer for measuring without an interferometer". On processing the phase carried by the optical field upon propagation to the target under test, a number of applications have been developed, including traditional measurements related to metrology and mechanical engineering - like displacement, distance, small-amplitude vibrations, attitude angles, velocity, as well as new measurements, like mechanical stress-strain hysterisis and microstructure/MEMS electro-mechanical response. In another field, sensing of motility finds direct application in a variety of biophysical measurements, like blood pulsation, respiratory sounds, chest acoustical impedance, and blood velocity profile. And, we may also look at the amplitude of the returning signal in a SMI, and we can measure weak optical echoes - for return loss and isolation factor measurements, CD readout and scroll sensing, and THz-wave detection. Last, the fine details of the SMI waveform reveal physical parameters of the laser like the laser linewidth, coherence length, and alpha factor. Worth to be noted, SMI is also a coherent detection scheme, and measurement close to the quantum limit of received field with minimum detectable displacements of 100 pm/√Hz are currently achieved upon operation on diffusive targets, whereas in detection mode returning signal can be sensed down to attenuations of -80dB.

  11. Tracking changes in volcanic systems with seismic Interferometry

    Science.gov (United States)

    Haney, Matt; Alicia J. Hotovec-Ellis,; Bennington, Ninfa L.; Silvio De Angelis,; Clifford Thurber,

    2014-01-01

    use ambient noise tomography (ANT) to map the 3D structure of a volcanic interior (at Piton de la Fournaise). Subsequent studies have imaged volcanoes with ANT at Okmok (Masterlark et al. 2010), Toba (Stankiewicz et al. 2010), Katmai (Thurber et al. 2012), Asama (Nagaoka et al. 2012), Uturuncu (Jay et al. 2012), and Kilauea (Ballmer et al. 2013b). In addition, Ma et al. (2013) have imaged a scatterer in the volcanic region of southern Peru by applying array techniques to ambient noise correlations. Prior to and in tandem with the development of ANT, researchers discovered that repeating earthquakes, which often occur at volcanoes, could be used to monitor subtle time-dependent changes with a technique known as the doublet method or coda wave interferometry (CWI) (Poupinet et al. 1984; Roberts et al. 1992; Ratdomopurbo and Poupinet 1995; Snieder et al. 2002; Pandolfi et al. 2006; Wegler et al. 2006; Martini et al. 2009; Haney et al. 2009; De Angelis 2009; Nagaoka et al. 2010; Battaglia et al. 2012; Erdem and Waite 2005; Hotovec-Ellis et al. 2014). Chaput et al. (2012) have also used scattered waves from Strombolian eruption coda at Erebus volcano to image the reflectivity of the volcanic interior with body wave interferometry. However, CWI in its original form was limited in that repeating earthquakes, or doublets, were not always guaranteed to occur. With the widespread use of noise correlations in seismology following the groundbreaking work by Campillo and Paul (2003) and Shapiro et al. (2005), it became evident that the nature of the ambient seismic field, due to its oceanic origin, enabled the continuous monitoring of subtle, time-dependent changes at both fault zones (Wegler and Sens-Schönfelder 2007; Brenguier et al. 2008b; Wegler et al. 2009; Sawazaki et al. 2009; Tatagi et al. 2012) and volcanoes (Sens-Schönfelder and Wegler 2006; Brenguier et al. 2008a) without the need for repeating earthquakes. Seismic precursors to eruptions based on ambient noise we

  12. Densitometry By Acoustic Levitation

    Science.gov (United States)

    Trinh, Eugene H.

    1989-01-01

    "Static" and "dynamic" methods developed for measuring mass density of acoustically levitated solid particle or liquid drop. "Static" method, unknown density of sample found by comparison with another sample of known density. "Dynamic" method practiced with or without gravitational field. Advantages over conventional density-measuring techniques: sample does not have to make contact with container or other solid surface, size and shape of samples do not affect measurement significantly, sound field does not have to be know in detail, and sample can be smaller than microliter. Detailed knowledge of acoustic field not necessary.

  13. Vibration Analysis Of Automotive Structures Using Holographic Interferometry

    Science.gov (United States)

    Brown, G. M.; Wales, R. R.

    1983-10-01

    Since 1979, Ford Motor Company has been developing holographic interferometry to supplement more conventional test methods to measure vehicle component vibrations. An Apollo PHK-1 Double Pulse Holographic Laser System was employed to visualize a variety of complex vibration modes, primarily on current production and prototype powertrain components. Design improvements to reduce powertrain response to problem excitations have been deter-mined through pulsed laser holography, and have, in several cases, been put into production in Ford vehicles. Whole-field definition of vibration related deflections provide continuity of information missed by accelerometer/modal analysis techniaues. Certain opera-tional problems, common among pulsed ruby holographic lasers, have reauired ongoing hardware and electronics improvements to minimize system downtime. Real-time, time-averaged and stroboscopic C. W. laser holographic techniques are being developed at Ford to complement the double pulse capabilities and provide rapid identification of modal frequencies and nodal lines for analysis of powertrain structures. Methods for mounting and exciting powertrains to minimize rigid body motions are discussed. Work at Ford will continue toward development of C. W. holographic techniques to provide refined test methodology dedicated to noise and vibration diagnostics with particular emphasis on semi-automated methods for quantifying displacement and relative phase using high resolution digitized video and computers. Continued use of refined pulsed and CW laser holographic interferometry for the analysis of complex structure vibrations seems assured.

  14. The Lindley paradox in optical interferometry

    International Nuclear Information System (INIS)

    Mauri, Camillo; Paris, Matteo G.A.

    2016-01-01

    The so-called Lindley paradox is a counterintuitive statistical effect where the Bayesian and frequentist approaches to hypothesis testing give radically different answers, depending on the choice of the prior distribution. In this paper we address the occurrence of the Lindley paradox in optical interferometry and discuss its implications for high-precision measurements. In particular, we focus on phase estimation by Mach–Zehnder interferometers and show how to mitigate the conflict between the two approaches by using suitable priors. - Highlights: • We address the occurence of Lindley paradox in interferometry and discuss its implications for high-precision measurements. • We show how to mitigate the conflict between Bayesian and frequentist approach to interferometry using suitable priors. • Our results apply to calibration of homodyne detectors for quantum tomography.

  15. Samuel A. Werner Pioneer of Neutron Interferometry

    International Nuclear Information System (INIS)

    Klein, Anthony

    2005-01-01

    Full text: In 1975, Sam Werner and his collaborators on the staff of the Scientific Laboratory of the Ford Motor Company carried out one of the pioneering experiments in neutron interferometry at the 2MW University of Michigan research reactor. It was the famous COW Experiment on gravitationally induced quantum interference. Shortly thereafter he moved to the University of Missouri in Columbia, to set up a program of neutron scattering research, including neutron interferometry. In the 25 years until his retirement a large number of beautiful experiments have been performed by Sam, with his group, his numerous students and many international collaborators. The Interferometry and Coherence session at this conference has been organized in his honour and the collected papers presented by his friends, collaborators and former students form his Festschrift. (author)

  16. Acoustics Research

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fisheries acoustics data are collected from more than 200 sea-days each year aboard the FRV DELAWARE II and FRV ALBATROSS IV (decommissioned) and the FSV Henry B....

  17. Acoustical Imaging

    CERN Document Server

    Akiyama, Iwaki

    2009-01-01

    The 29th International Symposium on Acoustical Imaging was held in Shonan Village, Kanagawa, Japan, April 15-18, 2007. This interdisciplinary Symposium has been taking place every two years since 1968 and forms a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. In the course of the years the volumes in the Acoustical Imaging Series have developed and become well-known and appreciated reference works. Offering both a broad perspective on the state-of-the-art in the field as well as an in-depth look at its leading edge research, this Volume 29 in the Series contains again an excellent collection of seventy papers presented in nine major categories: Strain Imaging Biological and Medical Applications Acoustic Microscopy Non-Destructive Evaluation and Industrial Applications Components and Systems Geophysics and Underwater Imaging Physics and Mathematics Medical Image Analysis FDTD method and Other Numerical Simulations Audience Researcher...

  18. Room Acoustics

    Science.gov (United States)

    Kuttruff, Heinrich; Mommertz, Eckard

    The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.

  19. Soft x-ray interferometry

    International Nuclear Information System (INIS)

    1993-09-01

    The purpose of the soft x-ray interferometry workshop held at Lawrence Berkeley Laboratory was to discuss with the scientific community the proposed technical design of the soft x-ray Fourier-transform spectrometer being developed at the ALS. Different design strategies for the instrument's components were discussed, as well as detection methods, signal processing issues, and how to meet the manufacturing tolerances that are necessary for the instrument to achieve the desired levels of performance. Workshop participants were encouraged to report on their experiences in the field of Fourier transform spectroscopy. The ALS is developing a Fourier transform spectrometer that is intended to operate up to 100 eV. The motivation is solely improved resolution and not the throughput (Jaquinot) or multiplex (Fellgett) advantage, neither of which apply for the sources and detectors used in this spectral range. The proposed implementation of this is via a Mach-Zehnder geometry that has been (1) distorted from a square to a rhombus to get grazing incidence of a suitable angle for 100 eV and (2) provided with a mirror-motion system to make the path difference between the interfering beams tunable. The experiment consists of measuring the emergent light intensity (I(x)) as a function of the path difference (x). The resolving power of the system is limited by the amount of path difference obtainable that is 1 cm (one million half-waves at 200 angstrom wavelength) in the design thus allowing a resolving power of one million. The free spectral range of the system is limited by the closeness with which the function I(x) is sampled. It is proposed to illuminate a helium absorption cell with roughly 1%-band-width light from a monochromator thus allowing one hundred aliases without spectral overlap even for sampling of I(x) at one hundredth of the Nyquist frequency

  20. Application of Phase Shifted, Laser Feedback Interferometry to Fluid Physics

    Science.gov (United States)

    Ovryn, Ben; Eppell, Steven J.; Andrews, James H.; Khaydarov, John

    1996-01-01

    We have combined the principles of phase-shifting interferometry (PSI) and laser-feedback interferometry (LFI) to produce a new instrument that can measure both optical path length (OPL) changes and discern sample reflectivity variations. In LFI, coherent feedback of the incident light either reflected directly from a surface or reflected after transmission through a region of interest will modulate the output intensity of the laser. LFI can yield a high signal-to-noise ratio even for low reflectivity samples. By combining PSI and LFI, we have produced a robust instrument, based upon a HeNe laser, with high dynamic range that can be used to measure either static (dc) or oscillatory changes along the optical path. As with other forms of interferometry, large changes in OPL require phase unwrapping. Conversely, small phase changes are limited by the fraction of a fringe that can be measured. We introduce the phase shifts with an electro-optic modulator (EOM) and use either the Carre or Hariharan algorithms to determine the phase and visibility. We have determined the accuracy and precision of our technique by measuring both the bending of a cantilevered piezoelectric bimorph and linear ramps to the EOM. Using PSI, sub-nanometer displacements can be measured. We have combined our interferometer with a commercial microscope and scanning piezoelectric stage and have measured the variation in OPL and visibility for drops of PDMS (silicone oil) on coated single crystal silicon. Our measurement of the static contact angle agrees with the value of 68 deg stated in the literature.

  1. Atmospheric Phase Delay in Sentinel SAR Interferometry

    Science.gov (United States)

    Krishnakumar, V.; Monserrat, O.; Crosetto, M.; Crippa, B.

    2018-04-01

    The repeat-pass Synthetic Aperture Radio Detection and Ranging (RADAR) Interferometry (InSAR) has been a widely used geodetic technique for observing the Earth's surface, especially for mapping the Earth's topography and deformations. However, InSAR measurements are prone to atmospheric errors. RADAR waves traverse the Earth's atmosphere twice and experience a delay due to atmospheric refraction. The two major layers of the atmosphere (troposphere and ionosphere) are mainly responsible for this delay in the propagating RADAR wave. Previous studies have shown that water vapour and clouds present in the troposphere and the Total Electron Content (TEC) of the ionosphere are responsible for the additional path delay in the RADAR wave. The tropospheric refractivity is mainly dependent on pressure, temperature and partial pressure of water vapour. The tropospheric refractivity leads to an increase in the observed range. These induced propagation delays affect the quality of phase measurement and introduce errors in the topography and deformation fields. The effect of this delay was studied on a differential interferogram (DInSAR). To calculate the amount of tropospheric delay occurred, the meteorological data collected from the Spanish Agencia Estatal de Meteorología (AEMET) and MODIS were used. The interferograms generated from Sentinel-1 carrying C-band Synthetic Aperture RADAR Single Look Complex (SLC) images acquired on the study area are used. The study area consists of different types of scatterers exhibiting different coherence. The existing Saastamoinen model was used to perform a quantitative evaluation of the phase changes caused by pressure, temperature and humidity of the troposphere during the study. Unless the phase values due to atmospheric disturbances are not corrected, it is difficult to obtain accurate measurements. Thus, the atmospheric error correction is essential for all practical applications of DInSAR to avoid inaccurate height and deformation

  2. ATMOSPHERIC PHASE DELAY IN SENTINEL SAR INTERFEROMETRY

    Directory of Open Access Journals (Sweden)

    V. Krishnakumar

    2018-04-01

    Full Text Available The repeat-pass Synthetic Aperture Radio Detection and Ranging (RADAR Interferometry (InSAR has been a widely used geodetic technique for observing the Earth’s surface, especially for mapping the Earth’s topography and deformations. However, InSAR measurements are prone to atmospheric errors. RADAR waves traverse the Earth’s atmosphere twice and experience a delay due to atmospheric refraction. The two major layers of the atmosphere (troposphere and ionosphere are mainly responsible for this delay in the propagating RADAR wave. Previous studies have shown that water vapour and clouds present in the troposphere and the Total Electron Content (TEC of the ionosphere are responsible for the additional path delay in the RADAR wave. The tropospheric refractivity is mainly dependent on pressure, temperature and partial pressure of water vapour. The tropospheric refractivity leads to an increase in the observed range. These induced propagation delays affect the quality of phase measurement and introduce errors in the topography and deformation fields. The effect of this delay was studied on a differential interferogram (DInSAR. To calculate the amount of tropospheric delay occurred, the meteorological data collected from the Spanish Agencia Estatal de Meteorología (AEMET and MODIS were used. The interferograms generated from Sentinel-1 carrying C-band Synthetic Aperture RADAR Single Look Complex (SLC images acquired on the study area are used. The study area consists of different types of scatterers exhibiting different coherence. The existing Saastamoinen model was used to perform a quantitative evaluation of the phase changes caused by pressure, temperature and humidity of the troposphere during the study. Unless the phase values due to atmospheric disturbances are not corrected, it is difficult to obtain accurate measurements. Thus, the atmospheric error correction is essential for all practical applications of DInSAR to avoid inaccurate

  3. Characterization of hidden defects of an original XVI century painting on wood by Electronic Speckle Pattern Interferometry (Electronic Speckle Pattern Interferometry survey on a wooden painting)

    International Nuclear Information System (INIS)

    Arena, G.

    2015-01-01

    Electronic Speckle Pattern Interferometry, a non-contact and nondestructive optical diagnostic technique, was employed for evaluating the conservation state of a XVI century painting on wood. The whole structure alterations, induced by the laboratory temperature and relative humidity variations, were evaluated. Long-term analysis, by sequential recording and subsequent off-line processing of the fringes progression, was carried out. Local flaws and hidden detachments of pictorial layers from the support, which could not be recognized by traditional art-restorer survey methods, were also easily revealed. In such a case, a simple measurement approach was utilized, with the aim to get a user-friendly method for art conservators. The results demonstrate that the interferometry method can largely improve the traditional art conservation survey techniques.

  4. Multi Temporal Interferometry as Tool for Urban Landslide Hazard Assessment

    Science.gov (United States)

    Vicari, A.; Colangelo, G.; Famiglietti, N.; Cecere, G.; Stramondo, S.; Viggiano, D.

    2017-12-01

    Advanced Synthetic Aperture Radar Differential Interferometry (A-DInSAR) are Multi Temporal Interferometry(MTI) techniques suitable for the monitoring of deformation phenomena in slow kinematics. A-DInSAR methodologies include both Coherence-based type, as well as Small Baseline Subset (SBAS) (Berardino et al., 2002, Lanari et al., 2004) and Persistent/Permanent Scatterers (PS), (Ferretti et al., 2001). Such techniques are capable to provide wide-area coverage (thousands of km2) and precise (mm-cm resolution), spatially dense information (from hundreds to thousands of measurementpoints/km2) on groundsurfacedeformations. SBAS and PShavebeenapplied to the town of Stigliano (MT) in Basilicata Region (Southern Italy), where the social center has been destroyed after the reactivation of a known landslide. The comparison of results has shown that these techniques are equivalent in terms of obtained coherent areas and displacement patterns, although lightly different velocity values for individual points (-5/-25 mm/y for PS vs. -5/-15 mm/y for SBAS) have been pointed out. Differences are probably due to scattering properties of the ground surface (e.g. Lauknes et al., 2010). Furthermore, on the crown of the landslide body, a Robotics Explorer Total Monitoring Station (Leica Nova TM50) that measures distance values with 0.6 mm of resolution has been installed. In particular, 20 different points corresponding to that identified through satellite techniques have been chosen, and a sampling time of 15 minutes has been fixed. The displacement values obtained are in agreement with the results of the MTI analysis, showing as these techniques could be a useful tool in the case of early - warning situations.

  5. Cold neutron interferometry and its application. 2. Coherency and cold neutron spin interferometry

    International Nuclear Information System (INIS)

    Achiwa, Norio; Ebisawa, Toru

    1998-03-01

    The second workshop entitled 'Interference studies and cold neutron spin interferometry' was held on 10 and 11 March 1998 at KUR (Kyoto University Research Reactor Institute, Kumatori). Cold neutron spin interferometry is a new field. So it is very important for its development to learn the studies of X-ray and neutron optics which are rapidly developing with long history. In the workshop, the issues related to interference were reviewed such as experimental studies on cold neutron spin interferometry, theoretical and experimental approach on tunneling time, interference experiments by neutrons and its application, interference studies using synchrotron radiation, topics on silicon interferometry and quantum measurement problem and cold neutron interference experiment related to quantum measurement problem. The 8 of the presented papers are indexed individually. (J.P.N.)

  6. Precision measurements with atom interferometry

    Science.gov (United States)

    Schubert, Christian; Abend, Sven; Schlippert, Dennis; Ertmer, Wolfgang; Rasel, Ernst M.

    2017-04-01

    Interferometry with matter waves enables precise measurements of rotations, accelerations, and differential accelerations [1-5]. This is exploited for determining fundamental constants [2], in fundamental science as e.g. testing the universality of free fall [3], and is applied for gravimetry [4], and gravity gradiometry [2,5]. At the Institut für Quantenoptik in Hannover, different approaches are pursued. A large scale device is designed and currently being set up to investigate the gain in precision for gravimetry, gradiometry, and fundamental tests on large baselines [6]. For field applications, a compact and transportable device is being developed. Its key feature is an atom chip source providing a collimated high flux of atoms which is expected to mitigate systematic uncertainties [7,8]. The atom chip technology and miniaturization benefits from microgravity experiments in the drop tower in Bremen and sounding rocket experiments [8,9] which act as pathfinders for space borne operation [10]. This contribution will report about our recent results. The presented work is supported by the CRC 1227 DQ-mat, the CRC 1128 geo-Q, the RTG 1729, the QUEST-LFS, and by the German Space Agency (DLR) with funds provided by the Federal Ministry of Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under Grant No. DLR 50WM1552-1557. [1] P. Berg et al., Phys. Rev. Lett., 114, 063002, 2015; I. Dutta et al., Phys. Rev. Lett., 116, 183003, 2016. [2] J. B. Fixler et al., Science 315, 74 (2007); G. Rosi et al., Nature 510, 518, 2014. [3] D. Schlippert et al., Phys. Rev. Lett., 112, 203002, 2014. [4] A. Peters et al., Nature 400, 849, 1999; A. Louchet-Chauvet et al., New J. Phys. 13, 065026, 2011; C. Freier et al., J. of Phys.: Conf. Series 723, 012050, 2016. [5] J. M. McGuirk et al., Phys. Rev. A 65, 033608, 2002; P. Asenbaum et al., arXiv:1610.03832. [6] J. Hartwig et al., New J. Phys. 17, 035011, 2015. [7] H. Ahlers et al., Phys. Rev. Lett. 116, 173601

  7. Optical transition radiation interferometry for the A0 photoinjector

    International Nuclear Information System (INIS)

    Kazakevich, G.; Novosibirsk, IYF; Edwards, H.; Fliller, R.; Nagaitsev, S.; Ruan, J.; Thurman-Keup, R.; Fermilab

    2008-01-01

    Optical Transition Radiation Interferometry (OTRI) is a promising diagnostic technique and has been successfully developed and used for investigation of relativistic beams. For mid-energy accelerators the technique is traditionally based on thin polymer films (the first one is being transparent for visible light), which causes beam multiple scattering of about 1 mrad. A disadvantage of those films is unacceptable vacuum properties for photoinjectors and accelerators using superconducting cavities. We have studied the application of thin mica sheets for the OTRI diagnostics at the A0 Photoinjector in comparison with 2.5 (micro)m thick Mylar films. This diagnostic is also applicable for the ILCTA-NML accelerator test facility that is planned at Fermilab. This report discusses the experimental setups of the OTR interferometer for the A0 Photoinjector and presents comparisons of simulations and measurements obtained using Mylar and mica-based interferometers

  8. Green's function representations for seismic interferometry

    NARCIS (Netherlands)

    Wapenaar, C.P.A.; Fokkema, J.T.

    2006-01-01

    The term seismic interferometry refers to the principle of generating new seismic responses by crosscorrelating seismic observations at different receiver locations. The first version of this principle was derived by Claerbout (1968), who showed that the reflection response of a horizontally layered

  9. Basic radio interferometry for future lunar missions

    NARCIS (Netherlands)

    Aminaei, Amin; Klein Wolt, Marc; Chen, Linjie; Bronzwaer, Thomas; Pourshaghaghi, Hamid Reza; Bentum, Marinus Jan; Falcke, Heino

    2014-01-01

    In light of presently considered lunar missions, we investigate the feasibility of the basic radio interferometry (RIF) for lunar missions. We discuss the deployment of two-element radio interferometer on the Moon surface. With the first antenna element is envisaged to be placed on the lunar lander,

  10. 3D super-virtual refraction interferometry

    KAUST Repository

    Lu, Kai; AlTheyab, Abdullah; Schuster, Gerard T.

    2014-01-01

    Super-virtual refraction interferometry enhances the signal-to-noise ratio of far-offset refractions. However, when applied to 3D cases, traditional 2D SVI suffers because the stationary positions of the source-receiver pairs might be any place

  11. Photopolymer for Optical Holography and Holographic Interferometry

    Czech Academy of Sciences Publication Activity Database

    Květoň, M.; Lédl, Vít; Havránek, A.; Fiala, P.

    2010-01-01

    Roč. 295, č. 1 (2010), s. 107-113 ISSN 1022-1360 Institutional research plan: CEZ:AV0Z20430508 Keywords : holographic interferometry * holography * photopolymerization * recording material * refractive index Subject RIV: BH - Optics, Masers, Lasers http://onlinelibrary.wiley.com/doi/10.1002/masy.200900093/pdf

  12. Real-time trichromatic holographic interferometry: preliminary study

    Science.gov (United States)

    Albe, Felix; Bastide, Myriam; Desse, Jean-Michel; Tribillon, Jean-Louis H.

    1998-08-01

    In this paper we relate our preliminary experiments on real- time trichromatic holographic interferometry. For this purpose a CW `white' laser (argon and krypton of Coherent- Radiation, Spectrum model 70) is used. This laser produces about 10 wavelengths. A system consisting of birefringent plates and polarizers allows to select a trichromatic TEM00 triplet: blue line ((lambda) equals 476 nm, 100 mW), green line ((lambda) equals 514 nm, 100 mW) and red line ((lambda) equals 647 nm, 100 mW). In a first stage we recorded a trichromatic reflection hologram with a separate reference beam on a single-layer silver-halide panchromatic plate (PFG 03C). After processing, the hologram is put back into the original recording set-up, as in classical experiments on real-time monochromatic holographic interferometry. So we observe interference fringes between the 3 reconstructed waves and the 3 actual waves. The interference fringes of the phenomenon are observed on a screen and recorded by a video camera at 25 frames per second. A color video film of about 3 minutes of duration is presented. Some examples related to phase objects are presented (hot airflow from a candle, airflow from a hand). The actual results show the possibility of using this technique to study, in real time, aerodynamic wakes and mechanical deformation.

  13. PVT Degradation Studies: Acoustic Diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Dib, Gerges [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tucker, Brian J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Smith, Philip J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-04-01

    Under certain environmental conditions, polyvinyl toluene (PVT) plastic scintillator has been observed to undergo internal fogging. This document reports on a study of acoustic techniques to determine whether they can provide a diagnostic for the fogging of PVT. Different ultrasound techniques were employed for detecting the level of internal fogging in PVT, including wave velocity measurements, attenuation, nonlinear acoustics, and acoustic microscopy. The results indicate that there are linear relations between the wave velocity and wave attenuation with the level of internal fogging. The effects of fogging on ultrasound wave attenuation is further verified by acoustic microscopy imaging, where regions with fog in the specimen demonstration higher levels of attenuation compared to clear regions. Results from the nonlinear ultrasound measurements were inconclusive due to high sensitivities to transducer coupling and fixture variabilities.

  14. Stable And Oscillating Acoustic Levitation

    Science.gov (United States)

    Barmatz, Martin B.; Garrett, Steven L.

    1988-01-01

    Sample stability or instability determined by levitating frequency. Degree of oscillation of acoustically levitated object along axis of levitation chamber controlled by varying frequency of acoustic driver for axis above or below frequency of corresponding chamber resonance. Stabilization/oscillation technique applied in normal Earth gravity, or in absence of gravity to bring object quickly to rest at nominal levitation position or make object oscillate in desired range about that position.

  15. Simplified Rotation In Acoustic Levitation

    Science.gov (United States)

    Barmatz, M. B.; Gaspar, M. S.; Trinh, E. H.

    1989-01-01

    New technique based on old discovery used to control orientation of object levitated acoustically in axisymmetric chamber. Method does not require expensive equipment like additional acoustic drivers of precisely adjustable amplitude, phase, and frequency. Reflecting object acts as second source of sound. If reflecting object large enough, close enough to levitated object, or focuses reflected sound sufficiently, Rayleigh torque exerted on levitated object by reflected sound controls orientation of object.

  16. Acoustic emission

    International Nuclear Information System (INIS)

    Straus, A.; Lopez Pumarega, M.I.; Di Gaetano, J.O.; D'Atellis, C.E.; Ruzzante, J.E.

    1990-01-01

    This paper is related to our activities on acoustic emission (A.E.). The work is made with different materials: metals and fibre reinforced plastics. At present, acoustic emission transducers are being developed for low and high temperature. A test to detect electrical discharges in electrical transformers was performed. Our experience in industrial tests to detect cracks or failures in tanks or tubes is also described. The use of A.E. for leak detection is considered. Works on pattern recognition of A.E. signals are also being performed. (Author)

  17. Building Acoustics

    Science.gov (United States)

    Cowan, James

    This chapter summarizes and explains key concepts of building acoustics. These issues include the behavior of sound waves in rooms, the most commonly used rating systems for sound and sound control in buildings, the most common noise sources found in buildings, practical noise control methods for these sources, and the specific topic of office acoustics. Common noise issues for multi-dwelling units can be derived from most of the sections of this chapter. Books can be and have been written on each of these topics, so the purpose of this chapter is to summarize this information and provide appropriate resources for further exploration of each topic.

  18. Analysis of the performance of interferometry, surface plasmon resonance and luminescence as biosensors and chemosensors

    International Nuclear Information System (INIS)

    Ince, R.; Narayanaswamy, R.

    2006-01-01

    Sensitivity, dynamic range and resolution have been calculated and compared from a range of analytes sensed in the literature using the techniques of interferometry, surface plasmon resonance (SPR) and luminescence. A detailed explanation of the physical and chemical/biological properties required of optical sensors is included along with the principle of operation of the sensors. Theoretical sensitivities of interferometry and SPR are also detailed along with parameters affecting these sensitivities. In the literature discussed in this review paper, the technique of luminescence, which relies intrinsically on 'labelling', offers the best resolutions for sensing of biomolecules (protein and DNA). Interference techniques offer the best resolutions for low molecular weight chemical liquids/vapours. Techniques which are 'label-free' are often desirable and it is demonstrated here that by combining the techniques of SPR with interferometry, it is possible to sense proteins with a resolution similar to that of luminescence. The future of chemo- and bio-sensing is discussed in terms of potential for multi-channel analysis, their continuous miniaturisation and their impending nanotechnology revolution

  19. Holograms for acoustics.

    Science.gov (United States)

    Melde, Kai; Mark, Andrew G; Qiu, Tian; Fischer, Peer

    2016-09-22

    Holographic techniques are fundamental to applications such as volumetric displays, high-density data storage and optical tweezers that require spatial control of intricate optical or acoustic fields within a three-dimensional volume. The basis of holography is spatial storage of the phase and/or amplitude profile of the desired wavefront in a manner that allows that wavefront to be reconstructed by interference when the hologram is illuminated with a suitable coherent source. Modern computer-generated holography skips the process of recording a hologram from a physical scene, and instead calculates the required phase profile before rendering it for reconstruction. In ultrasound applications, the phase profile is typically generated by discrete and independently driven ultrasound sources; however, these can only be used in small numbers, which limits the complexity or degrees of freedom that can be attained in the wavefront. Here we introduce monolithic acoustic holograms, which can reconstruct diffraction-limited acoustic pressure fields and thus arbitrary ultrasound beams. We use rapid fabrication to craft the holograms and achieve reconstruction degrees of freedom two orders of magnitude higher than commercial phased array sources. The technique is inexpensive, appropriate for both transmission and reflection elements, and scales well to higher information content, larger aperture size and higher power. The complex three-dimensional pressure and phase distributions produced by these acoustic holograms allow us to demonstrate new approaches to controlled ultrasonic manipulation of solids in water, and of liquids and solids in air. We expect that acoustic holograms will enable new capabilities in beam-steering and the contactless transfer of power, improve medical imaging, and drive new applications of ultrasound.

  20. Application of two-component phase doppler interferometry to the measurement of particle size, mass flux, and velocities in two-phase flows

    OpenAIRE

    McDonell, VG; Samuelsen, GS

    1989-01-01

    The application of two-component interferometry is described for the spatially-resolved measurement of particle size, velocity and mass flux as well as continuous phase velocity. Such a capability is important to develop an understanding of the physical processes attendant to two-phase flow systems, especially those involving liquid atomization typical of a wide class of combustion systems. Adapted from laser anemometry, the technique (phase Doppler interferometry) measures single particle ev...

  1. Acoustic Particle Detection with the ANTARES Detector

    Directory of Open Access Journals (Sweden)

    M. Neff

    2010-01-01

    Full Text Available The (Antares Modules for Acoustic Detection Under the Sea AMADEUS system within the (Astronomy with a Neutrino Telescope and Abyss environmental RESsearch ANTARES neutrino telescope is designed to investigate detection techniques for acoustic signals produced by particle cascades. While passing through a liquid a cascade deposits energy and produces a measurable pressure pulse. This can be used for the detection of neutrinos with energies exceeding 1018 eV. The AMADEUS setup consists of 36 hydrophones grouped in six local clusters measuring about one cubic meter each. This article focuses on acoustic particle detection, the hardware of the AMADEUS detector and techniques used for acoustic signal processing.

  2. Acoustic Particle Detection with the ANTARES Detector

    Directory of Open Access Journals (Sweden)

    Richardt C

    2010-01-01

    Full Text Available The (Antares Modules for Acoustic Detection Under the Sea AMADEUS system within the (Astronomy with a Neutrino Telescope and Abyss environmental RESsearch ANTARES neutrino telescope is designed to investigate detection techniques for acoustic signals produced by particle cascades. While passing through a liquid a cascade deposits energy and produces a measurable pressure pulse. This can be used for the detection of neutrinos with energies exceeding  eV. The AMADEUS setup consists of 36 hydrophones grouped in six local clusters measuring about one cubic meter each. This article focuses on acoustic particle detection, the hardware of the AMADEUS detector and techniques used for acoustic signal processing.

  3. Azimuthally sensitive Hanbury Brown-Twiss interferometry measured with the ALICE experiment

    Energy Technology Data Exchange (ETDEWEB)

    Gramling, Johanna Lena

    2011-07-01

    Bose-Einstein correlations of identical pions emitted in high-energy particle collisions provide information about the size of the source region in space-time. If analyzed via HBT Interferometry in several directions with respect to the reaction plane, the shape of the source can be extracted. Hence, HBT Interferometry provides an excellent tool to probe the characteristics of the quark-gluon plasma possibly created in high-energy heavy-ion collisions. This thesis introduces the main theoretical concepts of particle physics, the quark gluon plasma and the technique of HBT interferometry. The ALICE experiment at the CERN Large Hadron Collider (LHC) is explained and the first azimuthallyintegrated results measured in Pb-Pb collisions at √(s{sub NN})=2.76 TeV with ALICE are presented. A detailed two-track resolution study leading to a global pair cut for HBT analyses has been performed, and a framework for the event plane determination has been developed. The results from azimuthally sensitive HBT interferometry are compared to theoretical models and previous measurements at lower energies. Oscillations of the transverse radii in dependence on the pair emission angle are observed, consistent with a source that is extended out-of-plane.

  4. Evaluation of Acoustic Propagation Paths into the Human Head

    National Research Council Canada - National Science Library

    O'Brien, William D., Jr; Liu, Yuhui

    2005-01-01

    The overall goal of this research was to develop an acoustic wave propagation model using well-understood and documented computational techniques that track and quantify an air-borne incident acoustic...

  5. Handbook of Signal Processing in Acoustics

    CERN Document Server

    Havelock, David; Vorländer, Michael

    2009-01-01

    The Handbook of Signal Processing in Acoustics presents signal processing as it is practiced in the field of acoustics. The Handbook is organized by areas of acoustics, with recognized leaders coordinating the self-contained chapters of each section. It brings together a wide range of perspectives from over 100 authors to reveal the interdisciplinary nature of signal processing in acoustics. Success in acoustic applications often requires juggling both the acoustic and the signal processing parameters of the problem. This handbook brings the key issues from both into perspective and is complementary to other reference material on the two subjects. It is a unique resource for experts and practitioners alike to find new ideas and techniques within the diversity of signal processing in acoustics.

  6. Implant test and acoustic emission technique used to investigate hydrogen assisted cracking in the melted zone of a welded HSLA-80 steel

    International Nuclear Information System (INIS)

    Fals, H. C.; Trevisan, R. E.

    1999-01-01

    Weld metal hydrogen assisted cracking was studied using two flux cored wire (AWS E 70T-5 and AWS E 120 T5-K4) and a mixture gas of CO 2 +5% H 2 to induce values of diffusible hydrogen in high strength low alloy steel (HSLA-80) weldments. An acoustical Emission Measurement System (AEMS) RMS voltmeter was coupled to the implant test (NF 89-100) apparatus to determine energy, amplitude and event numbers of signal. All cracks were initiated in the partially melted zone and propagated into the coarse-grained region of the heat affected zone when E 70 T5 consumable was used, and the quasi-cleavage fracture mode was predominant. When E 120 T5 K4 consumable was used the cracks propagated vertically across the fusion zone, and a mixed fracture mode was the most important. A significant relationship between acoustic emission parameters and fracture modes was found. (Author) 12 refs

  7. Very Long Baseline Interferometry: Dependencies on Frequency Stability

    Science.gov (United States)

    Nothnagel, Axel; Nilsson, Tobias; Schuh, Harald

    2018-04-01

    Very Long Baseline Interferometry (VLBI) is a differential technique observing radiation of compact extra-galactic radio sources with pairs of radio telescopes. For these observations, the frequency standards at the telescopes need to have very high stability. In this article we discuss why this is, and we investigate exactly how precise the frequency standards need to be. Four areas where good clock performance is needed are considered: coherence, geodetic parameter estimation, correlator synchronization, and UT1 determination. We show that in order to ensure the highest accuracy of VLBI, stability similar to that of a hydrogen maser is needed for time-scales up to a few hours. In the article, we are considering both traditional VLBI where extra-galactic radio sources are observed, as well as observation of man-made artificial radio sources emitted by satellites or spacecrafts.

  8. Speckle interferometry application for erosion measurements in fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Gauthier, E.; Roupillard, R. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    2003-07-01

    In order to measure erosion/redeposition in fusion devices, a new diagnostic based on speckle interferometry is investigated. First experiments performed on carbon fibre composite (CFC) materials have shown that this technique is able to measure a modification of the surface in the range of 1 {mu}m. Further experiments have been performed on different materials using a second wavelength in order to carry out 3-dimensional measurements of the surface and to increase the dynamic range of the depth measurement. A diagnostic, based on two-wavelength TV-holography to measure in situ erosion/redeposition during long duration discharges on the CIEL limiter in Tore Supra, is under development at CEA Cadarache. (authors)

  9. Point source atom interferometry with a cloud of finite size

    Energy Technology Data Exchange (ETDEWEB)

    Hoth, Gregory W., E-mail: gregory.hoth@nist.gov; Pelle, Bruno; Riedl, Stefan; Kitching, John; Donley, Elizabeth A. [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

    2016-08-15

    We demonstrate a two axis gyroscope by the use of light pulse atom interferometry with an expanding cloud of atoms in the regime where the cloud has expanded by 1.1–5 times its initial size during the interrogation. Rotations are measured by analyzing spatial fringe patterns in the atom population obtained by imaging the final cloud. The fringes arise from a correlation between an atom's initial velocity and its final position. This correlation is naturally created by the expansion of the cloud, but it also depends on the initial atomic distribution. We show that the frequency and contrast of these spatial fringes depend on the details of the initial distribution and develop an analytical model to explain this dependence. We also discuss several challenges that must be overcome to realize a high-performance gyroscope with this technique.

  10. All-optical optoacoustic microscope based on wideband pulse interferometry.

    Science.gov (United States)

    Wissmeyer, Georg; Soliman, Dominik; Shnaiderman, Rami; Rosenthal, Amir; Ntziachristos, Vasilis

    2016-05-01

    Optical and optoacoustic (photoacoustic) microscopy have been recently joined in hybrid implementations that resolve extended tissue contrast compared to each modality alone. Nevertheless, the application of the hybrid technique is limited by the requirement to combine an optical objective with ultrasound detection collecting signal from the same micro-volume. We present an all-optical optoacoustic microscope based on a pi-phase-shifted fiber Bragg grating (π-FBG) with coherence-restored pulsed interferometry (CRPI) used as the interrogation method. The sensor offers an ultra-small footprint and achieved higher sensitivity over piezoelectric transducers of similar size. We characterize the spectral bandwidth of the ultrasound detector and interrogate the imaging performance on phantoms and tissues. We show the first optoacoustic images of biological specimen recorded with π-FBG sensors. We discuss the potential uses of π-FBG sensors based on CRPI.

  11. Rapid microcantilever-thickness determination by optical interferometry

    International Nuclear Information System (INIS)

    Salmon, Andrew R; Capener, Matthew J; Elliott, Stephen R; Baumberg, Jeremy J

    2014-01-01

    Silicon microcantilevers are widely used in scanning-probe microscopy and in cantilever-sensing applications. However, the cantilever thickness is not well controlled in conventional lithography and, since it is also difficult to measure, it is the most important undefined factor in mechanical variability. An accurate method to measure this parameter is thus essential. We demonstrate the capability to measure microcantilever thicknesses rapidly (>1 Hz) and accurately (±2 nm) by optical interferometry. This is achieved with standard microscopy equipment and so can be implemented as a standard technique in both research and in batch control for commercial microfabrication. In addition, we show how spatial variations in the thickness of individual microcantilevers can be mapped, which has applications in the precise mechanical calibration of cantilevers for force spectroscopy. (paper)

  12. Outdoor Acoustics as a General Discipline

    DEFF Research Database (Denmark)

    Rasmussen, Karsten Bo

    1999-01-01

    A tutorial paper exploring the characteristics of sound outdoors. Outdoor acoustics is contrasted to room acoustics. A number of important aspects of outdoor acoustics are exemplified and theoretical approaches are outlined. These are influence of ground impedance, influence of weather, screening...... to the application in question. In this way results providing a certain level of accuracy are obtained using methods which are balanced with the accuracy of the input data. Advanced measurement techniques are looked into and suggestions for future research are made...

  13. Kinetic Titration Series with Biolayer Interferometry

    Science.gov (United States)

    Frenzel, Daniel; Willbold, Dieter

    2014-01-01

    Biolayer interferometry is a method to analyze protein interactions in real-time. In this study, we illustrate the usefulness to quantitatively analyze high affinity protein ligand interactions employing a kinetic titration series for characterizing the interactions between two pairs of interaction patterns, in particular immunoglobulin G and protein G B1 as well as scFv IC16 and amyloid beta (1–42). Kinetic titration series are commonly used in surface plasmon resonance and involve sequential injections of analyte over a desired concentration range on a single ligand coated sensor chip without waiting for complete dissociation between the injections. We show that applying this method to biolayer interferometry is straightforward and i) circumvents problems in data evaluation caused by unavoidable sensor differences, ii) saves resources and iii) increases throughput if screening a multitude of different analyte/ligand combinations. PMID:25229647

  14. Permafrost Active Layer Seismic Interferometry Experiment (PALSIE).

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knox, Hunter Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); James, Stephanie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lee, Rebekah [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cole, Chris [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    We present findings from a novel field experiment conducted at Poker Flat Research Range in Fairbanks, Alaska that was designed to monitor changes in active layer thickness in real time. Results are derived primarily from seismic data streaming from seven Nanometric Trillium Posthole seismometers directly buried in the upper section of the permafrost. The data were evaluated using two analysis methods: Horizontal to Vertical Spectral Ratio (HVSR) and ambient noise seismic interferometry. Results from the HVSR conclusively illustrated the method's effectiveness at determining the active layer's thickness with a single station. Investigations with the multi-station method (ambient noise seismic interferometry) are continuing at the University of Florida and have not yet conclusively determined active layer thickness changes. Further work continues with the Bureau of Land Management (BLM) to determine if the ground based measurements can constrain satellite imagery, which provide measurements on a much larger spatial scale.

  15. Enhanced Interferometry with Programmable Spatial Light Modulator

    Science.gov (United States)

    2010-06-07

    Interferometry, Spatial Light Modulator, Surface Accuracy, Optics, Mirror, Zernike , Freeform Optics, Null Testing, Hartman, Wavefront 16. SECURITY...S L M P ix e l- c a m Tilted Flat Mirror L a s e r PV. ± 3.4 λ -Tilt by the flat mirror, ~7 waves ~ 14 fringes Interferogram 3D view (Various...Interferogram ( 3D view) x- profile y- profile (Various waveplates and telescopes not shown) SLM can compensate tilted wavefronts with an accuracy of

  16. Laser interferometry for the Big Bang Observer

    OpenAIRE

    Harry, Gregory M.; Fritschel, Peter; Shaddock, Daniel A.; Folkner, William; Phinney, E. Sterl

    2006-01-01

    The Big Bang Observer is a proposed space-based gravitational-wave detector intended as a follow on mission to the Laser Interferometer Space Antenna (LISA). It is designed to detect the stochastic background of gravitational waves from the early universe. We discuss how the interferometry can be arranged between three spacecraft for this mission and what research and development on key technologies are necessary to realize this scheme.

  17. Laser interferometry for the Big Bang Observer

    Energy Technology Data Exchange (ETDEWEB)

    Harry, Gregory M [LIGO Laboratory, Massachusetts Institute of Technology, NW17-161, Cambridge, MA 02139 (United States); Fritschel, Peter [LIGO Laboratory, Massachusetts Institute of Technology, NW17-161, Cambridge, MA 02139 (United States); Shaddock, Daniel A [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Folkner, William [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Phinney, E Sterl [California Institute of Technology, Pasadena, CA 91125 (United States)

    2006-08-07

    The Big Bang Observer is a proposed space-based gravitational-wave detector intended as a follow on mission to the Laser Interferometer Space Antenna (LISA). It is designed to detect the stochastic background of gravitational waves from the early universe. We discuss how the interferometry can be arranged between three spacecraft for this mission and what research and development on key technologies are necessary to realize this scheme.

  18. CMP reflection imaging via interferometry of distributed subsurface sources

    Science.gov (United States)

    Kim, D.; Brown, L. D.; Quiros, D. A.

    2015-12-01

    The theoretical foundations of recovering body wave energy via seismic interferometry are well established. However in practice, such recovery remains problematic. Here, synthetic seismograms computed for subsurface sources are used to evaluate the geometrical combinations of realistic ambient source and receiver distributions that result in useful recovery of virtual body waves. This study illustrates how surface receiver arrays that span a limited distribution suite of sources, can be processed to reproduce virtual shot gathers that result in CMP gathers which can be effectively stacked with traditional normal moveout corrections. To verify the feasibility of the approach in practice, seismic recordings of 50 aftershocks following the magnitude of 5.8 Virginia earthquake occurred in August, 2011 have been processed using seismic interferometry to produce seismic reflection images of the crustal structure above and beneath the aftershock cluster. Although monotonic noise proved to be problematic by significantly reducing the number of usable recordings, the edited dataset resulted in stacked seismic sections characterized by coherent reflections that resemble those seen on a nearby conventional reflection survey. In particular, "virtual" reflections at travel times of 3 to 4 seconds suggest reflector sat approximately 7 to 12 km depth that would seem to correspond to imbricate thrust structures formed during the Appalachian orogeny. The approach described here represents a promising new means of body wave imaging of 3D structure that can be applied to a wide array of geologic and energy problems. Unlike other imaging techniques using natural sources, this technique does not require precise source locations or times. It can thus exploit aftershocks too small for conventional analyses. This method can be applied to any type of microseismic cloud, whether tectonic, volcanic or man-made.

  19. Monitoring Seasonal Changes in Permafrost Using Seismic Interferometry

    Science.gov (United States)

    James, S. R.; Knox, H. A.; Abbott, R. E.

    2015-12-01

    The effects of climate change in polar regions and their incorporation in global climate models has recently become an area of great interest. Permafrost holds entrapped greenhouse gases, e.g. CO2 and CH4, which are released to the atmosphere upon thawing, creating a positive feedback mechanism. Knowledge of seasonal changes in active layer thickness as well as long term degradation of permafrost is critical to the management of high latitude infrastructures, hazard mitigation, and increasing the accuracy of climate predictions. Methods for effectively imaging the spatial extent, depth, thickness, and discontinuous nature of permafrost over large areas are needed. Furthermore, continuous monitoring of permafrost over annual time scales would provide valuable insight into permafrost degradation. Seismic interferometry using ambient seismic noise has proven effective for recording velocity changes within the subsurface for a variety of applications, but has yet to be applied to permafrost studies. To this end, we deployed 7 Nanometrics Trillium posthole broadband seismometers within Poker Flat Research Range, located 30 miles north of Fairbanks, Alaska in a zone of discontinuous permafrost. Approximately 2 years worth of nearly continuous ambient noise data was collected. Using the python package MSNoise, relative changes in velocity were calculated. Results show high amounts of variability throughout the study period. General trends of negative relative velocity shifts can be seen between August and October followed by a positive relative velocity shift between November and February. Differences in relative velocity changes with both frequency and spatial location are also observed, suggesting this technique is sensitive to permafrost variation with depth and extent. Overall, short and long term changes in shallow subsurface velocity can be recovered using this method proposing seismic interferometry is a promising new technique for permafrost monitoring. Sandia

  20. An Experimental Introduction to Acoustics

    Science.gov (United States)

    Black, Andy Nicholas; Magruder, Robert H.

    2017-11-01

    Learning and understanding physics requires more than studying physics texts. It requires doing physics. Doing research is a key opportunity for students to connect physical principles with their everyday experience. A powerful way to introduce students to research and technique is through subjects in which they might find interest. Presented is an experiment that serves to introduce an advanced undergraduate or high school student to conducting research in acoustics via an experiment involving a standard dreadnought acoustic guitar, recording industry-related equipment, and relevant industrial analysis software. This experimental process is applicable to a wide range of acoustical topics including both acoustic and electric instruments. Also, the student has a hands-on experience with relevant audio engineering technology to study physical principles.

  1. Acoustic agglomeration methods and apparatus

    Science.gov (United States)

    Barmatz, M. B. (Inventor)

    1984-01-01

    Methods are described for using acoustic energy to agglomerate fine particles on the order of one micron diameter that are suspended in gas, to provide agglomerates large enough for efficient removal by other techniques. The gas with suspended particles, is passed through the length of a chamber while acoustic energy at a resonant chamber mode is applied to set up one or more acoustic standing wave patterns that vibrate the suspended particles to bring them together so they agglomerate. Several widely different frequencies can be applied to efficiently vibrate particles of widely differing sizes. The standing wave pattern can be applied along directions transversed to the flow of the gas. The particles can be made to move in circles by applying acoustic energy in perpendicular directions with the energy in both directions being of the same wavelength but 90 deg out of phase.

  2. Development of Speckle Interferometry Algorithm and System

    International Nuclear Information System (INIS)

    Shamsir, A. A. M.; Jafri, M. Z. M.; Lim, H. S.

    2011-01-01

    Electronic speckle pattern interferometry (ESPI) method is a wholefield, non destructive measurement method widely used in the industries such as detection of defects on metal bodies, detection of defects in intergrated circuits in digital electronics components and in the preservation of priceless artwork. In this research field, this method is widely used to develop algorithms and to develop a new laboratory setup for implementing the speckle pattern interferometry. In speckle interferometry, an optically rough test surface is illuminated with an expanded laser beam creating a laser speckle pattern in the space surrounding the illuminated region. The speckle pattern is optically mixed with a second coherent light field that is either another speckle pattern or a smooth light field. This produces an interferometric speckle pattern that will be detected by sensor to count the change of the speckle pattern due to force given. In this project, an experimental setup of ESPI is proposed to analyze a stainless steel plate using 632.8 nm (red) wavelength of lights.

  3. Holographic interferometry of isolated deuterium plasmas produced by a CO2 laser

    International Nuclear Information System (INIS)

    Gatenby, P.V.; Walker, A.C.

    1978-10-01

    The application of double exposure fractional fringe holographic interferometry to measurements of electron density in a plasma generated by irradiation of a freely falling pellet of solid deuterium with a focused CO 2 laser pulse is discussed. A particularly simple technique is used for processing and reconstructing the holograms and this is described in detail. A summary and discussion of the results is included with the emphasis on the observed evolution of the deuterium plasma over the duration of the laser irradiation. (author)

  4. Visualization of flows in a motored rotary combustion engine using holographic interferometry

    Science.gov (United States)

    Hicks, Y. R.; Schock, H. J.; Craig, J. E.; Umstatter, H. L.; Lee, D. Y.

    1986-01-01

    The use of holographic interferometry to view the small- and large-scale flow field structures in the combustion chamber of a motored Wankel engine assembly is described. In order that the flow patterns of interest could be observed, small quantities of helium were injected with the intake air. Variation of the air flow patterns with engine speed, helium flow rate, and rotor position are described. The air flow at two locations within the combustion chamber was examined using this technique.

  5. Application Of Holographic Interferometry For Investigation Of Microroughness Of Engineering Surfaces

    Science.gov (United States)

    Lech, Marek; Mruk, Irena; Stupnicki, Jacek

    1985-01-01

    The paper describes an improved immersion method of holographic interferometry /IMHI/ adjusted for studies of roughness of engineering surfaces. Special optical arrangement, with two types of immersion cells and adequate technique of preparing transparent replicas reproducting with high fidelity details of differently machined surfaces was elaborated. It permits to obtain the contour maps of the surface asperities with intervals between the planes of succesive contour lines within a range of 1 μm. The results obtained for some engineering surfaces are given.

  6. Acoustic Territoriality

    DEFF Research Database (Denmark)

    Kreutzfeldt, Jacob

    2011-01-01

    Under the heading of "Gang i København" a number of initiatives was presented by the Lord Mayer and the Technical and Environmental Mayer of Copenhagen in May 2006. The aim of the initiative, which roughly translates to Lively Copenhagen, was both to make Copenhagen a livelier city in terms of city...... this article outline a few approaches to a theory of acoustic territoriality....

  7. Satellite based radar interferometry to estimate large-scale soil water depletion from clay shrinkage: possibilities and limitations

    NARCIS (Netherlands)

    Brake, te B.; Hanssen, R.F.; Ploeg, van der M.J.; Rooij, de G.H.

    2013-01-01

    Satellite-based radar interferometry is a technique capable of measuring small surface elevation changes at large scales and with a high resolution. In vadose zone hydrology, it has been recognized for a long time that surface elevation changes due to swell and shrinkage of clayey soils can serve as

  8. Spatial heterodyne interferometry of VY Canis Majoris, alpha Orionis, alpha Scorpii, and R Leonis at 11 microns

    International Nuclear Information System (INIS)

    Sutton, E.C.; Storey, J.W.V.; Betz, A.L.; Townes, C.H.; Spears, D.L.

    1977-01-01

    Using the technique of heterodyne interferometry, measurements were made of the spatial distribution of 11 micron radiation from four late type stars. The circumstellar shells surrounding VY Canis Majoris, alpha Orionis, and alpha Scorpii were resolved, whereas that of R Leonis was only partially resolved at a fringe spacing of 0.4 sec

  9. Spatial heterodyne interferometry of VY Canis Major's, alpha Orionis, alpha Scorpii, and R leonis at 11 microns

    Science.gov (United States)

    Sutton, E. C.; Storey, J. W. V.; Betz, A. L.; Townes, C. H.; Spears, D. L.

    1977-01-01

    Using the technique of heterodyne interferometry, measurements were made of the spatial distribution of 11 micron radiation from four late type stars. The circumstellar shells surrounding VY Canis Majoris, alpha Orionis, and alpha Scorpii were resolved, whereas that of R Leonis was only partially resolved at a fringe spacing of 0.4 sec.

  10. Readout for intersatellite laser interferometry: Measuring low frequency phase fluctuations of high-frequency signals with microradian precision

    DEFF Research Database (Denmark)

    Gerberding, Oliver; Diekmann, Christian; Kullmann, Joachim

    2015-01-01

    Precision phase readout of optical beat note signals is one of the core techniques required for inter-satellite laser interferometry. Future space based gravitational wave detectors like eLISA require such a readout over a wide range of MHz frequencies, due to orbit induced Doppler shifts...

  11. Acoustic lenses

    International Nuclear Information System (INIS)

    Kittmer, C.A.

    1983-03-01

    Acoustic lenses focus ultrasound to produce pencil-like beams with reduced near fields. When fitted to conventional (flat-faced) transducers, such lenses greatly improve the ability to detect and size defects. This paper describes a program developed to design acoustic lenses for use in immersion or contact inspection, using normal or angle beam mode with flat or curved targets. Lens surfaces are circular in geometry to facilitate machining. For normal beam inspection of flat plate, spherical or cylindrical lenses are used. For angle beam or curved surface inspections, a compound lens is required to correct for the extra induced aberration. Such a lens is aspherical with one radius of curvature in the plane of incidence, and a different radius of curvature in the plane perpendicular to the incident plane. The resultant beam profile (i.e., location of the acoustic focus, beam diameter, 6 dB working range) depends on the degree of focusing and the transducer used. The operating frequency and bandwidth can be affected by the instrumentation used. Theoretical and measured beam profiles are in good agreement. Various applications, from zone focusing used for defect sizing in thick plate, to line focusing for pipe weld inspection, are discussed

  12. Monitoring localized cracks on under pressure concrete nuclear containment wall using linear and nonlinear ultrasonic coda wave interferometry

    Science.gov (United States)

    Legland, J.-B.; Abraham, O.; Durand, O.; Henault, J.-M.

    2018-04-01

    Civil engineering is constantly demanding new methods for evaluation and non-destructive testing (NDT), particularly to prevent and monitor serious damage to concrete structures. Tn this work, experimental results are presented on the detection and characterization of cracks using nonlinear modulation of coda waves interferometry (NCWT) [1]. This method consists in mixing high-amplitude low-frequency acoustic waves with multi-scattered probe waves (coda) and analyzing their effects by interferometry. Unlike the classic method of coda analysis (CWT), the NCWT does not require the recording of a coda as a reference before damage to the structure. Tn the framework of the PTA-ENDE project, a 1/3 model of a preconstrained concrete containment (EDF VeRCoRs mock-up) is placed under pressure to study the leakage of the structure. During this evaluation protocol, specific areas are monitored by the NCWT (during 5 days, which correspond to the protocol of nuclear power plant pressurization under maintenance test). The acoustic nonlinear response due to the high amplitude of the acoustic modulation gives pertinent information about the elastic and dissipative nonlinearities of the concrete. Tts effective level is evaluated by two nonlinear observables extracted from the interferometry. The increase of nonlinearities is in agreement with the creation of a crack with a network of microcracks located at its base; however, a change in the dynamics of the evolution of the nonlinearities may indicate the opening of a through crack. Tn addition, as during the experimental campaign, reference codas have been recorded. We used CWT to follow the stress evolution and the gas leaks ratio of the structure. Both CWT and NCWT results are presented in this paper.

  13. Residual Stress Analysis Based on Acoustic and Optical Methods

    Directory of Open Access Journals (Sweden)

    Sanichiro Yoshida

    2016-02-01

    Full Text Available Co-application of acoustoelasticity and optical interferometry to residual stress analysis is discussed. The underlying idea is to combine the advantages of both methods. Acoustoelasticity is capable of evaluating a residual stress absolutely but it is a single point measurement. Optical interferometry is able to measure deformation yielding two-dimensional, full-field data, but it is not suitable for absolute evaluation of residual stresses. By theoretically relating the deformation data to residual stresses, and calibrating it with absolute residual stress evaluated at a reference point, it is possible to measure residual stresses quantitatively, nondestructively and two-dimensionally. The feasibility of the idea has been tested with a butt-jointed dissimilar plate specimen. A steel plate 18.5 mm wide, 50 mm long and 3.37 mm thick is braze-jointed to a cemented carbide plate of the same dimension along the 18.5 mm-side. Acoustoelasticity evaluates the elastic modulus at reference points via acoustic velocity measurement. A tensile load is applied to the specimen at a constant pulling rate in a stress range substantially lower than the yield stress. Optical interferometry measures the resulting acceleration field. Based on the theory of harmonic oscillation, the acceleration field is correlated to compressive and tensile residual stresses qualitatively. The acoustic and optical results show reasonable agreement in the compressive and tensile residual stresses, indicating the feasibility of the idea.

  14. Pattern recognition methods for acoustic emission analysis

    International Nuclear Information System (INIS)

    Doctor, P.G.; Harrington, T.P.; Hutton, P.H.

    1979-07-01

    Models have been developed that relate the rate of acoustic emissions to structural integrity. The implementation of these techniques in the field has been hindered by the noisy environment in which the data must be taken. Acoustic emissions from noncritical sources are recorded in addition to those produced by critical sources, such as flaws. A technique is discussed for prescreening acoustic events and filtering out those that are produced by noncritical sources. The methodology that was investigated is pattern recognition. Three different pattern recognition techniques were applied to a data set that consisted of acoustic emissions caused by crack growth and acoustic signals caused by extraneous noise sources. Examination of the acoustic emission data presented has uncovered several features of the data that can provide a reasonable filter. Two of the most valuable features are the frequency of maximum response and the autocorrelation coefficient at Lag 13. When these two features and several others were combined with a least squares decision algorithm, 90% of the acoustic emissions in the data set were correctly classified. It appears possible to design filters that eliminate extraneous noise sources from flaw-growth acoustic emissions using pattern recognition techniques

  15. Error analysis by means of acoustic holography

    International Nuclear Information System (INIS)

    Kutzner, J.; Wuestenberg, H.

    1976-01-01

    The possilbilities to use the acoustical holography in nondestructive testing are discussed. Although compared to optical holography the image quality of acoustical holography is reduced this technique can give important informations about the shape of defects. Especially in nondestructive testing of thick walled components no alternative exists until now. (orig.) [de

  16. Relationships between acoustic emissions and microstructures

    International Nuclear Information System (INIS)

    Rao, G.V.; Gopal, R.

    1979-01-01

    Results of a systematic study of 'microstructure-deformation-acoustic emission' relationships on two widely used pressure retaining component materials, namely A533-B nuclear pressure vessel steel and a 7075 aluminum alloy, are presented. The study consists of conducting acoustic monitored tensile tests on a variety of quenched and aged microstructures in the two alloy systems and extensive microstructural characterization of test specimens by light optic and electron microscopy techniques. The results suggest a consistent relationship between acoustic emissions and microdeformation mechanisms. The role of specific microstructural constituents in generating acoustic emissions in the two alloys is discussed. (author)

  17. Acoustic Neuroma Association

    Science.gov (United States)

    ... EVENTS DONATE NEWS Home Learn Back Learn about acoustic neuroma AN Facts What is acoustic neuroma? Diagnosing ... Brain Freeze ? READ MORE Read More What is acoustic neuroma? Identifying an AN Learn More Get Info ...

  18. Acoustic Green's function extraction in the ocean

    Science.gov (United States)

    Zang, Xiaoqin

    The acoustic Green's function (GF) is the key to understanding the acoustic properties of ocean environments. With knowledge of the acoustic GF, the physics of sound propagation, such as dispersion, can be analyzed; underwater communication over thousands of miles can be understood; physical properties of the ocean, including ocean temperature, ocean current speed, as well as seafloor bathymetry, can be investigated. Experimental methods of acoustic GF extraction can be categorized as active methods and passive methods. Active methods are based on employment of man-made sound sources. These active methods require less computational complexity and time, but may cause harm to marine mammals. Passive methods cost much less and do not harm marine mammals, but require more theoretical and computational work. Both methods have advantages and disadvantages that should be carefully tailored to fit the need of each specific environment and application. In this dissertation, we study one passive method, the noise interferometry method, and one active method, the inverse filter processing method, to achieve acoustic GF extraction in the ocean. The passive method of noise interferometry makes use of ambient noise to extract an approximation to the acoustic GF. In an environment with a diffusive distribution of sound sources, sound waves that pass through two hydrophones at two locations carry the information of the acoustic GF between these two locations; by listening to the long-term ambient noise signals and cross-correlating the noise data recorded at two locations, the acoustic GF emerges from the noise cross-correlation function (NCF); a coherent stack of many realizations of NCFs yields a good approximation to the acoustic GF between these two locations, with all the deterministic structures clearly exhibited in the waveform. To test the performance of noise interferometry in different types of ocean environments, two field experiments were performed and ambient noise

  19. Application of an Aligned and Unaligned Signal Processing Technique to Investigate Tones and Broadband Noise in Fan and Contra-Rotating Open Rotor Acoustic Spectra

    Science.gov (United States)

    Miles, Jeffrey Hilton; Hultgren, Lennart S.

    2015-01-01

    The study of noise from a two-shaft contra-rotating open rotor (CROR) is challenging since the shafts are not phase locked in most cases. Consequently, phase averaging of the acoustic data keyed to a single shaft rotation speed is not meaningful. An unaligned spectrum procedure that was developed to estimate a signal coherence threshold and reveal concealed spectral lines in turbofan engine combustion noise is applied to fan and CROR acoustic data in this paper (also available as NASA/TM-2015-218865). The NASA Advanced Air Vehicles Program, Advanced Air Transport Technology Project, Aircraft Noise Reduction Subproject supported the current work. The fan and open rotor data were obtained under previous efforts supported by the NASA Quiet Aircraft Technology (QAT) Project and the NASA Environmentally Responsible Aviation (ERA) Project of the Integrated Systems Research Program in collaboration with GE Aviation, respectively. The overarching goal of the Advanced Air Transport (AATT) Project is to explore and develop technologies and concepts to revolutionize the energy efficiency and environmental compatibility of fixed wing transport aircrafts. These technological solutions are critical in reducing the impact of aviation on the environment even as this industry and the corresponding global transportation system continue to grow.

  20. Prototype acoustic resonance spectroscopy monitor

    International Nuclear Information System (INIS)

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

    1996-03-01

    This report reports on work performed for the International Atomic Energy Agency (IAEA) through the Program Office for Technical Assistance (POTAS). In this work, we investigate possible applications of nondestructive acoustics measurements to facilitate IAEA safeguards at bulk processing facilities. Two different acoustic techniques for verifying the internal structure of a processing tank were investigated. During this effort we also examined two acoustic techniques for assessing the fill level within a processing tank. The fill-level measurements could be made highly portable and have an added safeguards advantage that they can also detect stratification of fill material. This later application may be particularly useful in confirming the absence of stratification in plutonium processing tanks before accountability samples are withdrawn

  1. Phase-shift interferometry with a digital photocamera

    International Nuclear Information System (INIS)

    Vannoni, Maurizio; Trivi, Marcelo; Molesini, Giuseppe

    2007-01-01

    A phase-shift interferometry experiment is proposed, working on a Twyman-Green optical configuration with additional polarization components. A guideline is provided to modern phase-shift interferometry, using concepts and laboratory equipment at the level of undergraduate optics courses

  2. Atom Interferometry for Fundamental Physics and Gravity Measurements in Space

    Science.gov (United States)

    Kohel, James M.

    2012-01-01

    Laser-cooled atoms are used as freefall test masses. The gravitational acceleration on atoms is measured by atom-wave interferometry. The fundamental concept behind atom interferometry is the quantum mechanical particle-wave duality. One can exploit the wave-like nature of atoms to construct an atom interferometer based on matter waves analogous to laser interferometers.

  3. Differential Interferometry Techniques on L-Band Data Employed for ...

    African Journals Online (AJOL)

    On the other hand, satellite remote sensing data provides a synoptic view of an area and the repeat image acquisition strategy implies that the long-term monitoring of surface deformation is a possibility. This paper investigates the use of L-band ALOS PALSAR data for the detection and monitoring of surface subsidence ...

  4. Utilization of InSAR differential interferometry for surface deformation detection caused by mining

    International Nuclear Information System (INIS)

    Yang, F.; Shao, Y.; Guichen, M.

    2010-01-01

    In China, the surface deformation of ground has been a significant geotechnical problem as a result of cracks in the ground surface, collapsing of house, and subsidence of roads. A powerful technology for detecting surface deformation in the ground is differential interferometry using synthetic aperture radar (INSAR). The technology enables the analysis from different phase of micro-wave between two observed data by synthetic aperture radar (SAR) of surface deformation of ground such as ground subsidence, land slide, and slope failure. In January 2006, the advanced land observing satellite was launched by the Japan Aerospace Exploration Agency. This paper presented an analytical investigation to detect ground subsidence or change caused by mining, overuse of ground water, and disaster. Specifically, the paper discussed the INSAR monitoring technology of the mine slope, including INSAR data sources and processing software; the principle of synthetic aperture radar interferometry; principles of differential SAR interferometry; and INSAR technology to slope monitoring of the Haizhou open pit mine. The paper also discussed the Haizhou strip mine side slope INSAR monitoring results and tests. It was concluded that the use of synthetic aperture radar interferometer technique was the optimal technique to provide three-dimensional spatial information and minimal change from ground surface by spatial remote sensing device. 18 refs., 5 figs.

  5. Development of Phase Detection Schemes Based on Surface Plasmon Resonance Using Interferometry

    Directory of Open Access Journals (Sweden)

    Muhammad Kashif

    2014-08-01

    Full Text Available Surface plasmon resonance (SPR is a novel optical sensing technique with a unique ability to monitor molecular binding in real-time for biological and chemical sensor applications. Interferometry is an excellent tool for accurate measurement of SPR changes, the measurement and comparison is made for the sensitivity, dynamic range and resolution of the different analytes using interferometry techniques. SPR interferometry can also employ phase detection in addition to the amplitude of the reflected light wave, and the phase changes more rapidly compared with other approaches, i.e., intensity, angle and wavelength. Therefore, the SPR phase interferometer offers the advantages of spatial phase resolution and high sensitivity. This work discusses the advancements in interferometric SPR methods to measure the phase shifts due to refractive index changes. The main application areas of SPR sensors are demonstrated, i.e., the Fabry-Perot interferometer, Michelson interferometer and Mach-Zehnder interferometer, with different configurations. The three interferometers are discussed in detail, and solutions are suggested to enhance the performance parameters that will aid in future biological and chemical sensors.

  6. Utilization of InSAR differential interferometry for surface deformation detection caused by mining

    Energy Technology Data Exchange (ETDEWEB)

    Yang, F. [Liaoning Technical Univ., Fuxin (China). School of Geomatics; Shao, Y. [Liaoning Technical Univ., Fuxin (China). Dept. of Foreign Language; Guichen, M. [Gifu Univ., Yanagido, Gifu (Japan). Dept. of Civil Engineering

    2010-07-01

    In China, the surface deformation of ground has been a significant geotechnical problem as a result of cracks in the ground surface, collapsing of house, and subsidence of roads. A powerful technology for detecting surface deformation in the ground is differential interferometry using synthetic aperture radar (INSAR). The technology enables the analysis from different phase of micro-wave between two observed data by synthetic aperture radar (SAR) of surface deformation of ground such as ground subsidence, land slide, and slope failure. In January 2006, the advanced land observing satellite was launched by the Japan Aerospace Exploration Agency. This paper presented an analytical investigation to detect ground subsidence or change caused by mining, overuse of ground water, and disaster. Specifically, the paper discussed the INSAR monitoring technology of the mine slope, including INSAR data sources and processing software; the principle of synthetic aperture radar interferometry; principles of differential SAR interferometry; and INSAR technology to slope monitoring of the Haizhou open pit mine. The paper also discussed the Haizhou strip mine side slope INSAR monitoring results and tests. It was concluded that the use of synthetic aperture radar interferometer technique was the optimal technique to provide three-dimensional spatial information and minimal change from ground surface by spatial remote sensing device. 18 refs., 5 figs.

  7. Crest Factor Reduction in MC-CDMA Employing Carrier Interferometry Codes

    Directory of Open Access Journals (Sweden)

    Natarajan Balasubramaniam

    2004-01-01

    Full Text Available This paper addresses signal compactness issues in MC-CDMA employing carrier interferometry codes using the measure of crest factor (CF. Carrier interferometry codes, applied to N -carrier MC-CDMA systems, enable 2N users to simultaneously share the system bandwidth with minimal degradation in performance (relative to the N -orthogonal-user case. First, for a fully loaded ( K=N and K=2N users MC-CDMA system with practical values of N , it is shown that the CF in downlink transmission demonstrates desirable properties of low mean and low variance. The downlink CF degrades when the number of users in the system decreases. Next, the high CF observed in the uplink is characterized and the poor CF in a partially loaded downlink as well as uplink is effectively combated using Schroeder's analytical CF reduction techniques.

  8. Relative astrometry of compact flaring structures in Sgr A* with polarimetric very long baseline interferometry

    International Nuclear Information System (INIS)

    Johnson, Michael D.; Doeleman, Sheperd S.; Fish, Vincent L.; Broderick, Avery E.; Wardle, John F. C.; Marrone, Daniel P.

    2014-01-01

    We demonstrate that polarimetric interferometry can be used to extract precise spatial information about compact polarized flares of Sgr A*. We show that, for a faint dynamical component, a single interferometric baseline suffices to determine both its polarization and projected displacement from the quiescent intensity centroid. A second baseline enables two-dimensional reconstruction of the displacement, and additional baselines can self-calibrate using the flare, enhancing synthesis imaging of the quiescent emission. We apply this technique to simulated 1.3 mm wavelength observations of a 'hot spot' embedded in a radiatively inefficient accretion disk around Sgr A*. Our results indicate that, even with current sensitivities, polarimetric interferometry with the Event Horizon Telescope can achieve ∼5 μas relative astrometry of compact flaring structures near Sgr A* on timescales of minutes.

  9. Holographic interferometry applied to the measurement of displacements of the interior points of transparent bodies.

    Science.gov (United States)

    Sciammarella, C A; Gilbert, J A

    1976-09-01

    Utilizing the light scattering property of transparent media, holographic interferometry is applied to the measurement of displacement at the interior planes of three dimensional bodies. The use of a double beam illumination and the introduction of a fictitious displacement make it feasible to obtain information corresponding to components of displacement projected on the scattering plane. When the proposed techniques are invoked, it is possible to eliminate the use of a matching index of refraction fluid in many problems involving symmetrically loaded prismatic bodies. Scattered light holographic interferometry is limited in its use to small changes in the index of refraction and to low values of relative retardation. In spite of these restrictions, a large number of technical problems in both statics and dynamics can be solved.

  10. Application of SAR interferometry to low-rate crustal deformation fields

    Science.gov (United States)

    Vincent, Paul

    Differential SAR interferometry is applied to the study of low-rate interseismic crustal deformation fields along three regions of the San Adreas fault system: Salton Sea (southernmost region), Pinto Mountain fault (south-central region), and San Francisco Bay (northern region). New techniques are developed to analyze and model these low-rate deformation fields including constrained horizontal-vertical component deconvolution, deformation phase pattern analysis and strain field evolution modeling. Several new active faults were discovered as well as unmeasured activity on existing faults in the process of this SAR interferometry study. The feasibility and limitations of InSAR as a tool to study low-rate deformation fields is also addressed.

  11. Acoustic tweezers: patterning cells and microparticles using standing surface acoustic waves (SSAW).

    Science.gov (United States)

    Shi, Jinjie; Ahmed, Daniel; Mao, Xiaole; Lin, Sz-Chin Steven; Lawit, Aitan; Huang, Tony Jun

    2009-10-21

    Here we present an active patterning technique named "acoustic tweezers" that utilizes standing surface acoustic wave (SSAW) to manipulate and pattern cells and microparticles. This technique is capable of patterning cells and microparticles regardless of shape, size, charge or polarity. Its power intensity, approximately 5x10(5) times lower than that of optical tweezers, compares favorably with those of other active patterning methods. Flow cytometry studies have revealed it to be non-invasive. The aforementioned advantages, along with this technique's simple design and ability to be miniaturized, render the "acoustic tweezers" technique a promising tool for various applications in biology, chemistry, engineering, and materials science.

  12. Effect of speech rate variation on acoustic phone stability in Afrikaans speech recognition

    CSIR Research Space (South Africa)

    Badenhorst, JAC

    2007-11-01

    Full Text Available The authors analyse the effect of speech rate variation on Afrikaans phone stability from an acoustic perspective. Specifically they introduce two techniques for the acoustic analysis of speech rate variation, apply these techniques to an Afrikaans...

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

    Science.gov (United States)

    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.

  14. Probing dark energy with atom interferometry

    International Nuclear Information System (INIS)

    Burrage, Clare; Copeland, Edmund J.; Hinds, E.A.

    2015-01-01

    Theories of dark energy require a screening mechanism to explain why the associated scalar fields do not mediate observable long range fifth forces. The archetype of this is the chameleon field. Here we show that individual atoms are too small to screen the chameleon field inside a large high-vacuum chamber, and therefore can detect the field with high sensitivity. We derive new limits on the chameleon parameters from existing experiments, and show that most of the remaining chameleon parameter space is readily accessible using atom interferometry

  15. Probing dark energy with atom interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Burrage, Clare; Copeland, Edmund J. [School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD (United Kingdom); Hinds, E.A., E-mail: Clare.Burrage@nottingham.ac.uk, E-mail: Edmund.Copeland@nottingham.ac.uk, E-mail: Ed.Hinds@imperial.ac.uk [Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom)

    2015-03-01

    Theories of dark energy require a screening mechanism to explain why the associated scalar fields do not mediate observable long range fifth forces. The archetype of this is the chameleon field. Here we show that individual atoms are too small to screen the chameleon field inside a large high-vacuum chamber, and therefore can detect the field with high sensitivity. We derive new limits on the chameleon parameters from existing experiments, and show that most of the remaining chameleon parameter space is readily accessible using atom interferometry.

  16. Baseline-dependent averaging in radio interferometry

    Science.gov (United States)

    Wijnholds, S. J.; Willis, A. G.; Salvini, S.

    2018-05-01

    This paper presents a detailed analysis of the applicability and benefits of baseline-dependent averaging (BDA) in modern radio interferometers and in particular the Square Kilometre Array. We demonstrate that BDA does not affect the information content of the data other than a well-defined decorrelation loss for which closed form expressions are readily available. We verify these theoretical findings using simulations. We therefore conclude that BDA can be used reliably in modern radio interferometry allowing a reduction of visibility data volume (and hence processing costs for handling visibility data) by more than 80 per cent.

  17. Frequency scanning interferometry for CLIC component fiducialisation

    CERN Document Server

    Kamugasa, Solomon William; Mainaud Durand, Helene; CERN. Geneva. ATS Department

    2016-01-01

    We present a strategy for the fiducialisation of CLIC’s Main Beam Quadrupole (MBQ) magnets using Frequency Scanning Interferometry (FSI). We have developed complementary device for a commercial FSI system to enable coordinate determination via multilateration. Using spherical high index glass retroreflectors with a wide acceptance angle, we optimise the geometry of measurement stations with respect to fiducials -- thus improving the precision of coordinates. We demonstrate through simulations that the 10 μm uncertainty required in the vertical and lateral axes for the fiducialisation of the MBQ can be attained using FSI multilateration.

  18. Balanced detection for self-mixing interferometry.

    Science.gov (United States)

    Li, Kun; Cavedo, Federico; Pesatori, Alessandro; Zhao, Changming; Norgia, Michele

    2017-01-15

    We propose a new detection scheme for self-mixing interferometry using two photodiodes for implementing a differential acquisition. The method is based on the phase opposition of the self-mixing signal measured between the two laser diode facet outputs. The subtraction of the two outputs implements a sort of balanced detection that improves the signal quality, and allows canceling of unwanted signals due to laser modulation and disturbances on laser supply and transimpedance amplifier. Experimental results demonstrate the benefits of differential acquisition in a system for both absolute distance and displacement-vibration measurement. This Letter provides guidance for the design of self-mixing interferometers using balanced detection.

  19. Panel acoustic contribution analysis.

    Science.gov (United States)

    Wu, Sean F; Natarajan, Logesh Kumar

    2013-02-01

    Formulations are derived to analyze the relative panel acoustic contributions of a vibrating structure. The essence of this analysis is to correlate the acoustic power flow from each panel to the radiated acoustic pressure at any field point. The acoustic power is obtained by integrating the normal component of the surface acoustic intensity, which is the product of the surface acoustic pressure and normal surface velocity reconstructed by using the Helmholtz equation least squares based nearfield acoustical holography, over each panel. The significance of this methodology is that it enables one to analyze and rank relative acoustic contributions of individual panels of a complex vibrating structure to acoustic radiation anywhere in the field based on a single set of the acoustic pressures measured in the near field. Moreover, this approach is valid for both interior and exterior regions. Examples of using this method to analyze and rank the relative acoustic contributions of a scaled vehicle cabin are demonstrated.

  20. Acoustic analysis of a piping system

    International Nuclear Information System (INIS)

    Misra, A.S.; Vijay, D.K.

    1996-01-01

    Acoustic pulsations in the Darlington Nuclear Generating Station, a 881 MW CANDU, primary heat transport piping system caused fuel bundle failures under short term operations. The problem was successfully analyzed using the steady-state acoustic analysis capability of the ABAQUS program. This paper describes in general, modelling of low amplitude acoustic pulsations in a liquid filled piping system using ABAQUS. The paper gives techniques for estimating the acoustic medium properties--bulk modulus, fluid density and acoustic damping--and modelling fluid-structure interactions at orifices and elbows. The formulations and techniques developed are benchmarked against the experiments given in 3 cited references. The benchmark analysis shows that the ABAQUS results are in excellent agreement with the experiments

  1. The acoustics of snoring.

    Science.gov (United States)

    Pevernagie, Dirk; Aarts, Ronald M; De Meyer, Micheline

    2010-04-01

    Snoring is a prevalent disorder affecting 20-40% of the general population. The mechanism of snoring is vibration of anatomical structures in the pharyngeal airway. Flutter of the soft palate accounts for the harsh aspect of the snoring sound. Natural or drug-induced sleep is required for its appearance. Snoring is subject to many influences such as body position, sleep stage, route of breathing and the presence or absence of sleep-disordered breathing. Its presentation may be variable within or between nights. While snoring is generally perceived as a social nuisance, rating of its noisiness is subjective and, therefore, inconsistent. Objective assessment of snoring is important to evaluate the effect of treatment interventions. Moreover, snoring carries information relating to the site and degree of obstruction of the upper airway. If evidence for monolevel snoring at the site of the soft palate is provided, the patient may benefit from palatal surgery. These considerations have inspired researchers to scrutinize the acoustic characteristics of snoring events. Similarly to speech, snoring is produced in the vocal tract. Because of this analogy, existing techniques for speech analysis have been applied to evaluate snoring sounds. It appears that the pitch of the snoring sound is in the low-frequency range (noise-like', and has scattered energy content in the higher spectral sub-bands (>500 Hz). To evaluate acoustic properties of snoring, sleep nasendoscopy is often performed. Recent evidence suggests that the acoustic quality of snoring is markedly different in drug-induced sleep as compared with natural sleep. Most often, palatal surgery alters sound characteristics of snoring, but is no cure for this disorder. It is uncertain whether the perceived improvement after palatal surgery, as judged by the bed partner, is due to an altered sound spectrum. Whether some acoustic aspects of snoring, such as changes in pitch, have predictive value for the presence of

  2. Reflection imaging of the Moon's interior using deep-moonquake seismic interferometry

    Science.gov (United States)

    Nishitsuji, Yohei; Rowe, C. A.; Wapenaar, Kees; Draganov, Deyan

    2016-04-01

    The internal structure of the Moon has been investigated over many years using a variety of seismic methods, such as travel time analysis, receiver functions, and tomography. Here we propose to apply body-wave seismic interferometry to deep moonquakes in order to retrieve zero-offset reflection responses (and thus images) beneath the Apollo stations on the nearside of the Moon from virtual sources colocated with the stations. This method is called deep-moonquake seismic interferometry (DMSI). Our results show a laterally coherent acoustic boundary around 50 km depth beneath all four Apollo stations. We interpret this boundary as the lunar seismic Moho. This depth agrees with Japan Aerospace Exploration Agency's (JAXA) SELenological and Engineering Explorer (SELENE) result and previous travel time analysis at the Apollo 12/14 sites. The deeper part of the image we obtain from DMSI shows laterally incoherent structures. Such lateral inhomogeneity we interpret as representing a zone characterized by strong scattering and constant apparent seismic velocity at our resolution scale (0.2-2.0 Hz).

  3. Precision displacement interferometry with stabilization of wavelength on air

    Directory of Open Access Journals (Sweden)

    Buchta Z.

    2013-05-01

    Full Text Available We present an interferometric technique based on differential interferometry setup for measurement in the subnanometer scale in atmospheric conditions. The motivation for development of this ultraprecise technique is coming from the field of nanometrology. The key limiting factor in any optical measurement are fluctuations of the refractive index of air representing a source of uncertainty on the 10-6level when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of overdetermined interferometric setup where a reference length is derived from a mechanical frame made from a material with very low thermal coefficient on the 10-8level. The technique allows to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third represents a reference for stabilization of the wavelength of the laser source. The principle is demonstrated on an experimental setup and a set of measurements describing the performance is presented.

  4. Baffling or Baffled: Improve Your Acoustics.

    Science.gov (United States)

    Abdoo, Frank B.

    1981-01-01

    Presents techniques for evaluating the acoustics (reverberation time, and standing waves and resonance phenomena) of a band performance room. Gives instructions for building and placing inexpensive baffles (free-standing, portable sound barriers) to correct room defects. (SJL)

  5. Bubble nucleation dynamics in 3He/4He mixture by holographic interferometry

    International Nuclear Information System (INIS)

    Morikawa, M; Abe, H; Nomura, R; Okuda, Y

    2009-01-01

    We were able to nucleate a gas bubble in the diluted phase of 3 He- 4 He mixture by a 1 ms width strong sound pulse. The nucleated bubble became large and detached from the bottom transducer and was pushed out to the bulk liquid by the acoustic wave pulse. The bubble then repeatedly expanded and contracted a few times and finally disappeared. The overall motion of the bubble was traced by a high speed camera with a time resolution of 1 ms. We are attempting to investigate the small density fluctuation around the bubble by incorporating holographic interferometry technology. The measurement was done at T=0.35 K for the phase separated mixture at saturated vapor pressure. An acoustic wave transducer was located at the bottom of the cell, so the bubble was nucleated in the dilute phase of the mixture. We resolved the density fluctuation as small as Δρ/ρ = 2 x 10 -6 in the dilute phase with the sample width of 25 mm, which could not be obtained by other methods. It was found that there appeared a less dense region of -Δρ/ρ ∼ 1.46 x 10 -3 just above the bubble. The bubble appeared just after the pulse was turned off, but this less dense region appeared prior to the emergence of the bulk bubble. It should be an important information about the bubble nucleation mechanism. This very high sensitivity of holographic interferometry with respect to the density fluctuation could be widely used in quantum liquid.

  6. Writing magnetic patterns with surface acoustic waves

    Energy Technology Data Exchange (ETDEWEB)

    Li, Weiyang; Buford, Benjamin; Jander, Albrecht; Dhagat, Pallavi, E-mail: dhagat@eecs.oregonstate.edu [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331 (United States)

    2014-05-07

    A novel patterning technique that creates magnetization patterns in a continuous magnetostrictive film with surface acoustic waves is demonstrated. Patterns of 10 μm wide stripes of alternating magnetization and a 3 μm dot of reversed magnetization are written using standing and focusing acoustic waves, respectively. The magnetization pattern is size-tunable, erasable, and rewritable by changing the magnetic field and acoustic power. This versatility, along with its solid-state implementation (no moving parts) and electronic control, renders it as a promising technique for application in magnetic recording, magnonic signal processing, magnetic particle manipulation, and spatial magneto-optical modulation.

  7. Persistent Scatterer Interferometry using Sentinel-1 Data

    Science.gov (United States)

    Monserrat, Oriol; Crosetto, Michele; Devanthery, Nuria; Cuevas-Gonzalez, Maria; Qihuan, Huang; Barra, Anna; Crippa, Bruno

    2016-04-01

    This work will be focused on the deformation measurement and monitoring using SAR imagery from the C-band Sentinel-1, a space mission funded by the European Union and carried out by the European Space Agency (ESA) within the Copernicus Programme. The work will firstly address the data processing and analysis procedure implemented by the authors. This includes both Persistent Scatterer Interferometry (PSI) tools to analyse large stacks of SAR images (say, typically more than 20 images), and Differential SAR Interferometry (DInSAR) tools to analyse short SAR image stacks. The work will discuss the characteristics of the main products derived by using Sentinel-1 DInSAR and PSI: deformation maps, deformation velocity maps, deformation time series, residual topographic error, etc. The analysis will be carried out over different types of land use area, e.g. urban, peri-urban and rural areas. The deformation monitoring based on Sentinel-1 data will be compared with the monitoring based on data from pre-existing missions, e.g. C-band ERS and Envisat, X-band TerraSAR-X and CosmoSkyMed, etc. The comparison will concern different study areas, mainly located in Italy and Spain.

  8. Astronomical optical interferometry, II: Astrophysical results

    Directory of Open Access Journals (Sweden)

    Jankov S.

    2011-01-01

    Full Text Available Optical interferometry is entering a new age with several ground- based long-baseline observatories now making observations of unprecedented spatial resolution. Based on a great leap forward in the quality and quantity of interferometric data, the astrophysical applications are not limited anymore to classical subjects, such as determination of fundamental properties of stars; namely, their effective temperatures, radii, luminosities and masses, but the present rapid development in this field allowed to move to a situation where optical interferometry is a general tool in studies of many astrophysical phenomena. Particularly, the advent of long-baseline interferometers making use of very large pupils has opened the way to faint objects science and first results on extragalactic objects have made it a reality. The first decade of XXI century is also remarkable for aperture synthesis in the visual and near-infrared wavelength regimes, which provided image reconstructions from stellar surfaces to Active Galactic Nuclei. Here I review the numerous astrophysical results obtained up to date, except for binary and multiple stars milliarcsecond astrometry, which should be a subject of an independent detailed review, taking into account its importance and expected results at microarcsecond precision level. To the results obtained with currently available interferometers, I associate the adopted instrumental settings in order to provide a guide for potential users concerning the appropriate instruments which can be used to obtain the desired astrophysical information.

  9. GLINT. Gravitational-wave laser INterferometry triangle

    Science.gov (United States)

    Aria, Shafa; Azevedo, Rui; Burow, Rick; Cahill, Fiachra; Ducheckova, Lada; Holroyd, Alexa; Huarcaya, Victor; Järvelä, Emilia; Koßagk, Martin; Moeckel, Chris; Rodriguez, Ana; Royer, Fabien; Sypniewski, Richard; Vittori, Edoardo; Yttergren, Madeleine

    2017-11-01

    When the universe was roughly one billion years old, supermassive black holes (103-106 solar masses) already existed. The occurrence of supermassive black holes on such short time scales are poorly understood in terms of their physical or evolutionary processes. Our current understanding is limited by the lack of observational data due the limits of electromagnetic radiation. Gravitational waves as predicted by the theory of general relativity have provided us with the means to probe deeper into the history of the universe. During the ESA Alpach Summer School of 2015, a group of science and engineering students devised GLINT (Gravitational-wave Laser INterferometry Triangle), a space mission concept capable of measuring gravitational waves emitted by black holes that have formed at the early periods after the big bang. Morespecifically at redshifts of 15 big bang) in the frequency range 0.01 - 1 Hz. GLINT design strain sensitivity of 5× 10^{-24} 1/√ { {Hz}} will theoretically allow the study of early black holes formations as well as merging events and collapses. The laser interferometry, the technology used for measuring gravitational waves, monitors the separation of test masses in free-fall, where a change of separation indicates the passage of a gravitational wave. The test masses will be shielded from disturbing forces in a constellation of three geocentric orbiting satellites.

  10. Spaceborne intensity interferometry via spacecraft formation flight

    Science.gov (United States)

    Ribak, Erez N.; Gurfil, Pini; Moreno, Coral

    2012-07-01

    Interferometry in space has marked advantages: long integration times and observation in spectral bands where the atmosphere is opaque. When installed on separate spacecraft, it also has extended and flexible baselines for better filling of the uv plane. Intensity interferometry has an additional advantage, being insensitive to telescope and path errors, but is unfortunately much less light-sensitive. In planning towards such a mission, we are experimenting with some fundamental research issues. Towards this end, we constructed a system of three vehicles floating on an air table in formation flight, with an autonomous orbit control. Each such device holds its own light collector, detector, and transmitter, to broadcast its intensity signal towards a central receiving station. At this station we implement parallel radio receivers, analogue to digital converters, and a digital three-way correlator. Current technology limits us to ~1GHz transmission frequency, which corresponds to a comfortable 0.3m accuracy in light-bucket shape and in its relative position. Naïve calculations place our limiting magnitude at ~7 in the blue and ultraviolet, where amplitude interferometers are limited. The correlation signal rides on top of this huge signal with its own Poisson noise, requiring a very large dynamic range, which needs to be transmitted in full. We are looking at open questions such as deployable optical collectors and radio antennae of similar size of a few meters, and how they might influence our data transmission and thus set our flux limit.

  11. Acoustic transducer

    Science.gov (United States)

    Drumheller, Douglas S.

    2000-01-01

    An active acoustic transducer tool for use down-hole applications. The tool includes a single cylindrical mandrel including a shoulder defining the boundary of a narrowed portion over which is placed a sandwich-style piezoelectric tranducer assembly. The piezoelectric transducer assembly is prestressed by being placed in a thermal interference fit between the shoulder of the mandrel and the base of an anvil which is likewise positioned over the narrower portion of the mandrel. In the preferred embodiment, assembly of the tool is accomplished using a hydraulic jack to stretch the mandrel prior to emplacement of the cylindrical sandwich-style piezoelectric transducer assembly and anvil. After those elements are positioned and secured, the stretched mandrel is allowed to return substantially to its original (pre-stretch) dimensions with the result that the piezoelectric transducer elements are compressed between the anvil and the shoulder of the mandrel.

  12. Acoustic cryocooler

    International Nuclear Information System (INIS)

    Swift, G.W.; Martin, R.A.; Radebaugh, R.

    1990-01-01

    This patent describes an acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effect to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15--60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintain a cooling load of 5 W at 80 K

  13. Use of acoustic vortices in acoustic levitation

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...

  14. The use of Electronic Speckle Pattern Interferometry (ESPI) in the crack propagation analysis of epoxy resins

    Science.gov (United States)

    Herbert, D. P.; Al-Hassani, A. H. M.; Richardson, M. O. W.

    The ESPI (electronic speckle pattern interferometry) technique at high magnification levels is demonstrated to be of considerable value in interpreting the fracture behaviour of epoxy resins. The fracture toughness of powder coating system at different thicknesses has been measured using a TDCB (tapered double cantilever beam) technique and the deformation zone at the tip of the moving crack monitored. Initial indications are that a mechanistic changeover occurs at a critical bond (coating) thickness and that this is synonymous with the occurence of a fracture toughness maximum, which in turn is associated with a deformation zone of specific diameter.

  15. Dynamic Deformation of ETNA Volcano Observed by GPS and SAR Interferometry

    Science.gov (United States)

    Lundgren, P.; Rosen, P.; Webb, F.; Tesauro, M.; Lanari, R.; Sansosi, E.; Puglisi, G.; Bonforte, A.; Coltelli, M.

    1999-01-01

    Synthetic aperture radar (SAR) interferometry and GPS have shown that during the quiescent period from 1993-1995 Mt. Etna volcano, Italy, inflated. Since the initiation of eruptive activity since late 1995 the deformation has been more contentious. We will explore the detailed deformation during the period from 1995-1996 spanning the late stages of inflation and the beginning of eruptive activity. We use SAR interferometry and GPS data to measure the volcano deformation. We invert the observed deformation for both simple point source. le crack elastic sources or if warranted for a spheroidal pressure So In particular, we will examine the evolution of the inflation and the transition to a lesser deflation observed at the end of 1995. We use ERS-1/2 SAR data from both ascending and descending passes to allow for dense temporal 'sampling of the deformation and to allow us to critically assess atmospheric noise. Preliminary results from interferometry suggest that the inflation rate accelerated prior to resumption of activity in 1995, while GPS data suggest a more steady inflation with some fluctuation following the start of activity. This study will compare and contrast the interferometric SAR and GPS results and will address the strengths and weaknesses of each technique towards volcano deformation studies.

  16. A portable magneto-optical trap with prospects for atom interferometry in civil engineering.

    Science.gov (United States)

    Hinton, A; Perea-Ortiz, M; Winch, J; Briggs, J; Freer, S; Moustoukas, D; Powell-Gill, S; Squire, C; Lamb, A; Rammeloo, C; Stray, B; Voulazeris, G; Zhu, L; Kaushik, A; Lien, Y-H; Niggebaum, A; Rodgers, A; Stabrawa, A; Boddice, D; Plant, S R; Tuckwell, G W; Bongs, K; Metje, N; Holynski, M

    2017-08-06

    The high precision and scalable technology offered by atom interferometry has the opportunity to profoundly affect gravity surveys, enabling the detection of features of either smaller size or greater depth. While such systems are already starting to enter into the commercial market, significant reductions are required in order to reach the size, weight and power of conventional devices. In this article, the potential for atom interferometry based gravimetry is assessed, suggesting that the key opportunity resides within the development of gravity gradiometry sensors to enable drastic improvements in measurement time. To push forward in realizing more compact systems, techniques have been pursued to realize a highly portable magneto-optical trap system, which represents the core package of an atom interferometry system. This can create clouds of 10 7 atoms within a system package of 20 l and 10 kg, consuming 80 W of power.This article is part of the themed issue 'Quantum technology for the 21st century'. © 2017 The Author(s).

  17. An investigation of CO2 laser scleral buckling using moiré interferometry.

    Science.gov (United States)

    Maswadi, Saher M; Dyer, Peter E; Verma, Dinesh; Jalabi, Wadah; Dave, Dinesh

    2002-01-01

    To demonstrate suitability of moiré interferometry to assess and quantify laser-induced shrinkage of scleral collagen for buckling procedures. Scleral buckling of human cadaver eyes was investigated using a Coherent Ultrapulse CO2 laser. Projection moiré interferometry was employed to determine the out-of plane displacement produced by laser exposure, and in-situ optical microscopy of reference markers on the eye was used to measure in-plane shrinkage. Measurements based on moiré interferometry allow a three dimensional view of shape changes in the eye surface as laser treatment proceeds. Out-of-plane displacement reaches up to 1.5 mm with a single laser spot exposure. In-plane shrinkage reached a maximum of around 30%, which is similar to that reported by Sasoh et al (Ophthalmic Surg Lasers. 1998;29:410) for a Tm:YAG laser. The moiré technique is found to be suitable for quantifying the effects of CO2 laser scleral shrinkage and buckling. This can be further developed to provide a standardized method for experimental investigations of other laser sources for scleral shrinkage.

  18. Interior acoustic cloak

    OpenAIRE

    Wael Akl; A. Baz

    2014-01-01

    Acoustic cloaks have traditionally been intended to externally surround critical objects to render these objects acoustically invisible. However, in this paper, the emphasis is placed on investigating the application of the acoustic cloaks to the interior walls of acoustic cavities in an attempt to minimize the noise levels inside these cavities. In this manner, the acoustic cloaks can serve as a viable and efficient alternative to the conventional passive noise attenuation treatments which a...

  19. Supersonic acoustic intensity with statistically optimized near-field acoustic holography

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn

    2011-01-01

    The concept of supersonic acoustic intensity was introduced some years ago for estimating the fraction of the flow of energy radiated by a source that propagates to the far field. It differs from the usual (active) intensity by excluding the near-field energy resulting from evanescent waves...... to the information provided by the near-field acoustic holography technique. This study proposes a version of the supersonic acoustic intensity applied to statistically optimized near-field acoustic holography (SONAH). The theory, numerical results and an experimental study are presented. The possibility of using...

  20. Recovery of the Earth's Gravity Field Based on Spaceborne Atom-interferometry and Its Accuracy Estimation

    Directory of Open Access Journals (Sweden)

    ZHU Zhu

    2017-09-01

    Full Text Available The electrostatic gravity gradiometer has been successfully applied as a core sensor in satellite gravity gradiometric mission GOCE, and its observations are used to recover the Earth's static gravity field with a degree and order above 200. The lifetime of GOCE has been over, and the next generation satellite gravity gradiometry with higher resolution is urgently required in order to recover the global steady-state gravity field with a degree and order of 200~360. High potential precision can be obtained in space by atom-interferometry gravity gradiometer due to its long interference time, and thus the atom-interferometry-based satellite gravity gradiometry has been proposed as one of the candidate techniques for the next satellite gravity gradiometric mission. In order to achieve the science goal for high resolution gravity field measurement in the future, a feasible scheme of atom-interferometry gravity gradiometry in micro-gravity environment is given in this paper, and the gravity gradient measurement can be achieved with a noise of 0.85mE/Hz1/2. Comparison and estimation of the Earth's gravity field recovery precision for different types of satellite gravity gradiometry is discussed, and the results show that the satellite gravity gradiometry based on atom-interferometry is expected to provide the global gravity field model with an improved accuracy of 7~8cm in terms of geoid height and 3×10-5 m/s2 in terms of gravity anomaly respectively at a degree and order of 252~290.

  1. Acoustic multivariate condition monitoring - AMCM

    Energy Technology Data Exchange (ETDEWEB)

    Rosenhave, P E [Vestfold College, Maritime Dept., Toensberg (Norway)

    1998-12-31

    In Norway, Vestfold College, Maritime Department presents new opportunities for non-invasive, on- or off-line acoustic monitoring of rotating machinery such as off-shore pumps and diesel engines. New developments within acoustic sensor technology coupled with chemometric data analysis of complex signals now allow condition monitoring of hitherto unavailable flexibility and diagnostic specificity. Chemometrics paired with existing knowledge yields a new and powerful tool for condition monitoring. By the use of multivariate techniques and acoustics it is possible to quantify wear and tear as well as predict the performance of working components in complex machinery. This presentation describes the AMCM method and one result of a feasibility study conducted onboard the LPG/C `Norgas Mariner` owned by Norwegian Gas Carriers as (NGC), Oslo. (orig.) 6 refs.

  2. Acoustic multivariate condition monitoring - AMCM

    Energy Technology Data Exchange (ETDEWEB)

    Rosenhave, P.E. [Vestfold College, Maritime Dept., Toensberg (Norway)

    1997-12-31

    In Norway, Vestfold College, Maritime Department presents new opportunities for non-invasive, on- or off-line acoustic monitoring of rotating machinery such as off-shore pumps and diesel engines. New developments within acoustic sensor technology coupled with chemometric data analysis of complex signals now allow condition monitoring of hitherto unavailable flexibility and diagnostic specificity. Chemometrics paired with existing knowledge yields a new and powerful tool for condition monitoring. By the use of multivariate techniques and acoustics it is possible to quantify wear and tear as well as predict the performance of working components in complex machinery. This presentation describes the AMCM method and one result of a feasibility study conducted onboard the LPG/C `Norgas Mariner` owned by Norwegian Gas Carriers as (NGC), Oslo. (orig.) 6 refs.

  3. Resolving power test of 2-D K+ K+ interferometry

    International Nuclear Information System (INIS)

    Padula, Sandra S.; Roldao, Christiane G.

    1999-01-01

    Adopting a procedure previously proposed to quantitatively study pion interferometry 1 , an equivalent 2-D X 2 analysis was performed to test the resolving power of that method when applied to less favorable conditions, when no significant contribution from long lived resonances is expected, as in kaon interferometry. For that purpose, use is made of the preliminary E859 K + K + interferometry data from Si+Au collisions at 14.6 A GeV/c. Less sensitivity is achieved in the present case, although it is shown that it is still possible to distinguish two distinct decoupling geometries. (author)

  4. Acoustic leak detection in nuclear power plants

    International Nuclear Information System (INIS)

    McElroy, J.W.

    1986-01-01

    For several years now, utilities have been utilizing acoustic leak detection methods as an operating tool in their nuclear power stations. The purpose for using the leak detection system at the various stations vary from safety, ALARA, improved operations, preventive maintenance, or increased plant availability. This paper describes the various acoustic techniques and their application. The techniques are divided into three categories: specific component leakage, intersystem leakage, and pipe through-wall crack leakage. The paper addresses each category in terms of motivation to monitor, method of application and operation, and benefits to be gained. Current requirements are reviewed and analyzed with respect to the acoustic techniques. The paper shows how acoustic leak detection is one of the most effective leak detection tools available. 9 figures, 1 table

  5. Acoustic emission from polycrystalline graphites

    International Nuclear Information System (INIS)

    Ioka, I.; Yoda, S.; Oku, T.; Miyamoto, Y.

    1987-01-01

    Acoustic emission was monitored from polycrystalline graphites with different microstructure (pore size and pore volume) subjected to compressive loading. The graphites used in this study comprised five brands, that is, PGX, ISEM-1, IG-11, IG-15, and ISO-88. A root mean square (RMS) voltage and event counts of acoustic emission for graphites were measured during compressive loading. The acoustic emission was measured using a computed-based data acquisition and analysis system. The graphites were first deformed up to 80 % of the average fracture stress, then unloaded and reloaded again until the fracture occured. During the first loading, the change in RMS voltage for acoustic emission was detected from the initial stage. During the unloading, the RMS voltage became zero level as soon as the applied stress was released and then gradually rose to a peak and declined. The behavior indicated that the reversed plastic deformation occured in graphites. During the second loading, the RMS voltage gently increased until the applied stress exceeded the maximum stress of the first loading; there is no Kaiser effect in the graphites. A bicrystal model could give a reasonable explanation of this results. The empirical equation between the ratio of σ AE to σ f and σ f was obtained. It is considered that the detection of microfracture by the acoustic emission technique is effective in macrofracture prediction of polycrystalline graphites. (author)

  6. Cerebellar interaction with the acoustic reflex.

    Science.gov (United States)

    Jastreboff, P J

    1981-01-01

    The involvement of the cerebellar vermis in the acoustic reflex was analyzed in 12 cats, decerebrated or in pentobarbital anesthesia. Anatomical data suggested the existence of a connection of lobules VIII with the ventral cochlear nucleus. Single cell recording and evoked potential techniques demonstrated the existence of the acoustic projection to lobulus VIII. Electrical stimulation of this area changed the tension of the middle ear muscle and caused evoked potential responses in the caudal part of the ventral cochlear nucleus. Electrical stimulation of the motor nucleus of the facial nerve evoked a slow wave in the recording taken from the surrounding of the cochlear round window. A hypothesis is proposed which postulates the involvement of the acoustic reflex in space localization of acoustic stimuli and the action of cerebellar vermis in order to assure the stability and plasticity of the acoustic reflex arc.

  7. Springer Handbook of Acoustics

    CERN Document Server

    Rossing, Thomas D

    2007-01-01

    Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and others. The Springer Handbook of Acoustics is an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents spanning: animal acoustics including infrasound and ultrasound, environmental noise control, music and human speech and singing, physiological and psychological acoustics, architectural acoustics, physical and engineering acoustics, signal processing, medical acoustics, and ocean acoustics. This handbook reviews the most important areas of acoustics, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest rese...

  8. Responsive acoustic surfaces

    DEFF Research Database (Denmark)

    Peters, Brady; Tamke, Martin; Nielsen, Stig Anton

    2011-01-01

    Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....

  9. Multi-Axis Heterodyne Interferometry (MAHI)

    Science.gov (United States)

    Thorpe, James

    The detection and measurement of gravitational waves represents humanity’s next, and final, opportunity to open an entirely new spectrum with which to view the universe. The first steps of this process will likely take place later this decade when the second-generation ground-based instruments such as Advanced LIGO approach design sensitivity. While these events will be historic, it will take a space-based detector to access the milliHertz gravitational wave frequency band, a band that is rich in both number and variety of sources. The Laser Interferometer Space Antenna (LISA) concept has been developed over the past two decades in the US and Europe to provide access to this band. The European Space Agency recently selected The Gravitational Universe as the science theme for the 3rd Large-class mission in the Cosmic Visions Programme, with the assumption that a LISA-like instrument would be implemented for launch in 2034. NASA has expressed interest in partnering on this effort and the US community has made its own judgment on the scientific potential of a space-based gravitational wave observatory through the selection of LISA as the 3rd flagship mission in the 2010 Decadal Survey. Much of the effort has been in retiring risk for the unique technologies that comprise a gravitational wave detector. A prime focus of this effort is LISA Pathfinder (LPF), a dedicated technology demonstrator mission led by ESA with contributions from NASA and several member states. LPF’s primary objective is to validate drag-free flight as an approach to realizing an inertial reference mass. Along the way, several important technologies will be demonstrated, including picometer-level heterodyne interferometry. However, there are several important differences between the interferometry design for LISA and that for LPF. These mostly result from the fact that LISA interferometry involves multiple lasers on separate spacecraft whereas LPF can use a single laser on a single spacecraft

  10. Atom-surface potentials and atom interferometry

    International Nuclear Information System (INIS)

    Babb, J.F.

    1998-01-01

    Long-range atom-surface potentials characterize the physics of many actual systems and are now measurable spectroscopically in deflection of atomic beams in cavities or in reflection of atoms in atomic fountains. For a ground state, spherically symmetric atom the potential varies as -1/R 3 near the wall, where R is the atom-surface distance. For asymptotically large distances the potential is weaker and goes as -1/R 4 due to retardation arising from the finite speed of light. This diminished interaction can also be interpreted as a Casimir effect. The possibility of measuring atom-surface potentials using atomic interferometry is explored. The particular cases studied are the interactions of a ground-state alkali-metal atom and a dielectric or a conducting wall. Accurate descriptions of atom-surface potentials in theories of evanescent-wave atomic mirrors and evanescent wave-guided atoms are also discussed. (author)

  11. Real time processor for array speckle interferometry

    International Nuclear Information System (INIS)

    Chin, G.; Florez, J.; Borelli, R.; Fong, W.; Miko, J.; Trujillo, C.

    1989-01-01

    With the construction of several new large aperture telescopes and the development of large format array detectors in the near IR, the ability to obtain diffraction limited seeing via IR array speckle interferometry offers a powerful tool. We are constructing a real-time processor to acquire image frames, perform array flat-fielding, execute a 64 x 64 element 2D complex FFT, and to average the power spectrum all within the 25 msec coherence time for speckles at near IR wavelength. The processor is a compact unit controlled by a PC with real time display and data storage capability. It provides the ability to optimize observations and obtain results on the telescope rather than waiting several weeks before the data can be analyzed and viewed with off-line methods

  12. Unification of nonclassicality measures in interferometry

    Science.gov (United States)

    Yuan, Xiao; Zhou, Hongyi; Gu, Mile; Ma, Xiongfeng

    2018-01-01

    From an operational perspective, nonclassicality characterizes the exotic behavior in a physical process which cannot be explained with Newtonian physics. There are several widely used measures of nonclassicality, including coherence, discord, and entanglement, each proven to be essential resources in particular situations. There exists evidence of fundamental connections among the three measures. However, the sources of nonclassicality are still regarded differently and such connections are yet to be elucidated. Here, we introduce a general framework of defining a unified nonclassicality with an operational motivation founded on the capability of interferometry. Nonclassicality appears differently as coherence, discord, and entanglement in different scenarios with local measurement, weak basis-independent measurement, and strong basis-independent measurement, respectively. Our results elaborate how these three measures are related and how they can be transformed from each other. Experimental schemes are proposed to test the results.

  13. Compressed-sensing wavenumber-scanning interferometry

    Science.gov (United States)

    Bai, Yulei; Zhou, Yanzhou; He, Zhaoshui; Ye, Shuangli; Dong, Bo; Xie, Shengli

    2018-01-01

    The Fourier transform (FT), the nonlinear least-squares algorithm (NLSA), and eigenvalue decomposition algorithm (EDA) are used to evaluate the phase field in depth-resolved wavenumber-scanning interferometry (DRWSI). However, because the wavenumber series of the laser's output is usually accompanied by nonlinearity and mode-hop, FT, NLSA, and EDA, which are only suitable for equidistant interference data, often lead to non-negligible phase errors. In this work, a compressed-sensing method for DRWSI (CS-DRWSI) is proposed to resolve this problem. By using the randomly spaced inverse Fourier matrix and solving the underdetermined equation in the wavenumber domain, CS-DRWSI determines the nonuniform sampling and spectral leakage of the interference spectrum. Furthermore, it can evaluate interference data without prior knowledge of the object. The experimental results show that CS-DRWSI improves the depth resolution and suppresses sidelobes. It can replace the FT as a standard algorithm for DRWSI.

  14. Edge effects in composites by moire interferometry

    Science.gov (United States)

    Czarnek, R.; Post, D.; Herakovich, C.

    1983-01-01

    The very high sensitivity of moire interferometry has permitted the present edge effect experiments to be conducted at a low average stress and strain level, assuring linear and elastic behavior in the composite material samples tested. Sensitivity corresponding to 2450 line/mm moire was achieved with a 0.408 micron/fringe. Simultaneous observations of the specimen face and edge displacement fields showed good fringe definition despite the 1-mm thickness of the specimens and the high gradients, and it is noted that the use of a carrier pattern and optical filtering was effective in even these conditions. Edge effects and dramatic displacement gradients were confirmed in angle-ply composite laminates.

  15. Airy acoustical-sheet spinner tweezers

    Science.gov (United States)

    Mitri, F. G.

    2016-09-01

    The Airy acoustical beam exhibits parabolic propagation and spatial acceleration, meaning that the propagation bending angle continuously increases before the beam trajectory reaches a critical angle where it decays after a propagation distance, without applying any external bending force. As such, it is of particular importance to investigate its properties from the standpoint of acoustical radiation force, spin torque, and particle dynamics theories, in the development of novel particle sorting techniques and acoustically mediated clearing systems. This work investigates these effects on a two-dimensional (2D) circular absorptive structure placed in the field of a nonparaxial Airy "acoustical-sheet" (i.e., finite beam in 2D), for potential applications in surface acoustic waves and acousto-fluidics. Based on the characteristics of the acoustic field, the beam is capable of manipulating the circular cylindrical fluid cross-section and guides it along a transverse or parabolic trajectory. This feature of Airy acoustical beams could lead to a unique characteristic in single-beam acoustical tweezers related to acoustical sieving, filtering, and removal of particles and cells from a section of a small channel. The analysis developed here is based on the description of the nonparaxial Airy beam using the angular spectrum decomposition of plane waves in close association with the partial-wave series expansion method in cylindrical coordinates. The numerical results demonstrate the ability of the nonparaxial Airy acoustical-sheet beam to pull, propel, or accelerate a particle along a parabolic trajectory, in addition to particle confinement in the transverse direction of wave propagation. Negative or positive radiation force and spin torque causing rotation in the clockwise or the anticlockwise direction can occur depending on the nondimensional parameter ka (where k is the wavenumber and a is the radius) and the location of the cylinder in the beam. Applications in

  16. Investigation of surface deformations by double exposure holographic interferometry

    International Nuclear Information System (INIS)

    Ecevit, F.N.; Guven, H.; Aydin, R.

    1990-01-01

    Surface deformations of rigid bodies produced by thermal as well as mechanical strains have been investigated using double-exposure holographic interferometry. The recorded interference fringes have been discussed qualitatively. (author). 9 refs, 4 figs

  17. Two-dimensional χ2 analysis in kaon interferometry

    International Nuclear Information System (INIS)

    Roldao, C.G.; Padula, S.S.

    1997-01-01

    This work presents preliminary results obtained from the χ 2 analysis performed on the E 859 Joint Work data. The work objective is to quantify the resolution power of the kaon two-dimension interferometry

  18. Observational Model for Precision Astrometry with the Space Interferometry Mission

    National Research Council Canada - National Science Library

    Turyshev, Slava G; Milman, Mark H

    2000-01-01

    The Space Interferometry Mission (SIM) is a space-based 10-m baseline Michelson optical interferometer operating in the visible waveband that is designed to achieve astrometric accuracy in the single digits of the microarcsecond domain...

  19. Acoustics an introduction

    CERN Document Server

    Kuttruff, Heinrich

    2006-01-01

    This definitive textbook provides students with a comprehensive introduction to acoustics. Beginning with the basic physical ideas, Acoustics balances the fundamentals with engineering aspects, applications and electroacoustics, also covering music, speech and the properties of human hearing. The concepts of acoustics are exposed and applied in:room acousticssound insulation in buildingsnoise controlunderwater sound and ultrasoundScientifically thorough, but with mathematics kept to a minimum, Acoustics is the perfect introduction to acoustics for students at any level of mechanical, electrical or civil engineering courses and an accessible resource for architects, musicians or sound engineers requiring a technical understanding of acoustics and their applications.

  20. Seismic interferometry : Reconstructing the earth's reflection response

    NARCIS (Netherlands)

    Draganov, D.S.; Wapenaar, C.P.A.; Thorbecke, J.W.

    2006-01-01

    In 1968, Jon Claerbout showed that the reflection response of a 1D acoustic medium can be reconstructed by autocorrelating the transmission response. Since then, several authors have derived relationships for reconstructing Green's functions at the surface, using crosscorrelations of (noise)

  1. Acoustic source for generating an acoustic beam

    Science.gov (United States)

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian

    2016-05-31

    An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.

  2. Flaw identification using acoustic emission

    International Nuclear Information System (INIS)

    Woodward, B.; McDonald, N.R.

    1975-01-01

    Acoustic emission 'signatures' contain information about the fine structure of metallurgical source events and their interpretation may provide a means of assessing the severity of internal flaws as well as surface flaws. The ultimate aim of this research on signature analysis is to develop a real time non-destructive testing technique having the capability of flaw recognition as well as flaw location in nuclear reactor components and structures under stress. Thus the requisite, unlike that in most acoustic emission work to date, is for a technique which affords discrimination between acoustic emission from different types of flaws propagating simultaneously. The approach described here requires detailed analysis of the emission signatures in terms of a specific statistical parameter, energy spectral density. In order to realise the full inspection potential of acoustic emission monitoring data obtained from zirconium and steel testpieces have been correlated with metallurgical condition and mechanical behaviour, since the nature of emission signatures is strongly affected by the physical characteristics and internal structure of the material. (Auth.)

  3. Ipsilateral masking between acoustic and electric stimulations.

    Science.gov (United States)

    Lin, Payton; Turner, Christopher W; Gantz, Bruce J; Djalilian, Hamid R; Zeng, Fan-Gang

    2011-08-01

    Residual acoustic hearing can be preserved in the same ear following cochlear implantation with minimally traumatic surgical techniques and short-electrode arrays. The combined electric-acoustic stimulation significantly improves cochlear implant performance, particularly speech recognition in noise. The present study measures simultaneous masking by electric pulses on acoustic pure tones, or vice versa, to investigate electric-acoustic interactions and their underlying psychophysical mechanisms. Six subjects, with acoustic hearing preserved at low frequencies in their implanted ear, participated in the study. One subject had a fully inserted 24 mm Nucleus Freedom array and five subjects had Iowa/Nucleus hybrid implants that were only 10 mm in length. Electric masking data of the long-electrode subject showed that stimulation from the most apical electrodes produced threshold elevations over 10 dB for 500, 625, and 750 Hz probe tones, but no elevation for 125 and 250 Hz tones. On the contrary, electric stimulation did not produce any electric masking in the short-electrode subjects. In the acoustic masking experiment, 125-750 Hz pure tones were used to acoustically mask electric stimulation. The acoustic masking results showed that, independent of pure tone frequency, both long- and short-electrode subjects showed threshold elevations at apical and basal electrodes. The present results can be interpreted in terms of underlying physiological mechanisms related to either place-dependent peripheral masking or place-independent central masking.

  4. Integrating acoustic analysis in the architectural design process using parametric modelling

    DEFF Research Database (Denmark)

    Peters, Brady

    2011-01-01

    This paper discusses how parametric modeling techniques can be used to provide architectural designers with a better understanding of the acoustic performance of their designs and provide acoustic engineers with models that can be analyzed using computational acoustic analysis software. Architects......, acoustic performance can inform the geometry and material logic of the design. In this way, the architectural design and the acoustic analysis model become linked....

  5. Applications of atom interferometry - from ground to space

    Science.gov (United States)

    Schubert, Christian; Rasel, Ernst Maria; Gaaloul, Naceur; Ertmer, Wolfgang

    2016-07-01

    Atom interferometry is utilized for the measurement of rotations [1], accelerations [2] and for tests of fundamental physics [3]. In these devices, three laser light pulses separated by a free evolution time coherently manipulate the matter waves which resembles the Mach-Zehnder geometry in optics. Atom gravimeters demonstrated an accuracy of few microgal [2,4], and atom gradiometers showed a noise floor of 30 E Hz^{-1/2} [5]. Further enhancements of atom interferometers are anticipated by the integration of novel source concepts providing ultracold atoms, extending the free fall time of the atoms, and enhanced techniques for coherent manipulation. Sources providing Bose-Einstein condensates recently demontrated a flux compatible with precision experiments [6]. All of these aspects are studied in the transportable quantum gravimeter QG-1 and the very long baseline atom interferometry teststand in Hannover [7] with the goal of surpassing the microgal regime. Going beyond ground based setups, the QUANTUS collaboration exploits the unique features of a microgravity environment in drop tower experiments [8] and in a sounding rocket mission. The payloads are compact and robust atom optics experiments based on atom chips [6], enabling technology for transportable sensors on ground as a byproduct. More prominently, they are pathfinders for proposed satellite missions as tests of the universality of free fall [9] and gradiometry based on atom interferometers [10]. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50WM1552-1557 (QUANTUS-IV-Fallturm) and by the Deutsche Forschungsgemeinschaft in the framework of the SFB 1128 geo-Q. [1] PRL 114 063002 2015 [2] Nature 400 849 1999 [3] PRL 112 203002 2014 [4] NJP 13 065026 2011 [5] PRA 65 033608 2002 [6] NJP 17 065001 2015 [7] NJP 17 035011 2015 [8] PRL 110 093602 2013 [9

  6. Prosthetic clone and natural human tooth comparison by speckle interferometry

    Science.gov (United States)

    Slangen, Pierre; Corn, Stephane; Fages, Michel; Raynal, Jacques; Cuisinier, Frederic J. G.

    2010-09-01

    New trends in dental prosthodontic interventions tend to preserve the maximum of "body" structure. With the evolution of CAD-CAM techniques, it is now possible to measure "in mouth" the remaining dental tissues. The prosthetic crown is then designed using this shape on which it will be glued on, and also by taking into account the contact surface of the opposite jaw tooth. Several theories discuss on the glue thickness and formulation, but also on the way to evolve to a more biocompatible crown and also new biomechanical concepts. In order to validate these new concepts and materials, and to study the mechanical properties and mechanical integrity of the prosthesis, high resolution optical measurements of the deformations of the glue and the crown are needed. Samples are two intact premolars extracted for orthodontics reasons. The reference sample has no modifications on the tooth while the second sample tooth is shaped to receive a feldspathic ceramic monoblock crown which will be glued. This crown was manufactured with a chairside CAD-CAM system from an intra-oral optical print. The software allows to realize a nearly perfect clone of the reference sample. The necessary space for the glue is also entered with ideal values. This duplication process yields to obtain two samples with identical anatomy for further processing. The glue joint thickness can also be modified if required. The purpose is to compare the behaviour of a natural tooth and its prosthetic clone manufactured with "biomechanical" concepts. Vertical cut samples have been used to deal with planar object observation, and also to look "inside" the tooth. We have developed a complete apparatus enabling the study of the compressive mechanical behaviour of the concerned tooth by speckle interferometry. Because in plane displacements are of great interest for orthodontic measurements1, an optical fiber in-plane sensitive interferometer has been designed. The fibers are wrapped around piezoelectric

  7. Interior acoustic cloak

    Directory of Open Access Journals (Sweden)

    Wael Akl

    2014-12-01

    Full Text Available Acoustic cloaks have traditionally been intended to externally surround critical objects to render these objects acoustically invisible. However, in this paper, the emphasis is placed on investigating the application of the acoustic cloaks to the interior walls of acoustic cavities in an attempt to minimize the noise levels inside these cavities. In this manner, the acoustic cloaks can serve as a viable and efficient alternative to the conventional passive noise attenuation treatments which are invariably heavy and bulky. The transformation acoustics relationships that govern the operation of this class of interior acoustic cloaks are presented. Physical insights are given to relate these relationships to the reasons behind the effectiveness of the proposed interior acoustic cloaks. Finite element models are presented to demonstrate the characteristics of interior acoustic cloaks used in treating the interior walls of circular and square cavities both in the time and frequency domains. The obtained results emphasize the effectiveness of the proposed interior cloaks in eliminating the reflections of the acoustic waves from the walls of the treated cavities and thereby rendering these cavities acoustically quiet. It is important to note here that the proposed interior acoustic cloaks can find applications in acoustic cavities such as aircraft cabins and auditoriums as well as many other critical applications.

  8. Mesospheric gravity wave momentum flux estimation using hybrid Doppler interferometry

    Directory of Open Access Journals (Sweden)

    A. J. Spargo

    2017-06-01

    Full Text Available Mesospheric gravity wave (GW momentum flux estimates using data from multibeam Buckland Park MF radar (34.6° S, 138.5° E experiments (conducted from July 1997 to June 1998 are presented. On transmission, five Doppler beams were symmetrically steered about the zenith (one zenith beam and four off-zenith beams in the cardinal directions. The received beams were analysed with hybrid Doppler interferometry (HDI (Holdsworth and Reid, 1998, principally to determine the radial velocities of the effective scattering centres illuminated by the radar. The methodology of Thorsen et al. (1997, later re-introduced by Hocking (2005 and since extensively applied to meteor radar returns, was used to estimate components of Reynolds stress due to propagating GWs and/or turbulence in the radar resolution volume. Physically reasonable momentum flux estimates are derived from the Reynolds stress components, which are also verified using a simple radar model incorporating GW-induced wind perturbations. On the basis of these results, we recommend the intercomparison of momentum flux estimates between co-located meteor radars and vertical-beam interferometric MF radars. It is envisaged that such intercomparisons will assist with the clarification of recent concerns (e.g. Vincent et al., 2010 of the accuracy of the meteor radar technique.

  9. Mesospheric gravity wave momentum flux estimation using hybrid Doppler interferometry

    Science.gov (United States)

    Spargo, Andrew J.; Reid, Iain M.; MacKinnon, Andrew D.; Holdsworth, David A.

    2017-06-01

    Mesospheric gravity wave (GW) momentum flux estimates using data from multibeam Buckland Park MF radar (34.6° S, 138.5° E) experiments (conducted from July 1997 to June 1998) are presented. On transmission, five Doppler beams were symmetrically steered about the zenith (one zenith beam and four off-zenith beams in the cardinal directions). The received beams were analysed with hybrid Doppler interferometry (HDI) (Holdsworth and Reid, 1998), principally to determine the radial velocities of the effective scattering centres illuminated by the radar. The methodology of Thorsen et al. (1997), later re-introduced by Hocking (2005) and since extensively applied to meteor radar returns, was used to estimate components of Reynolds stress due to propagating GWs and/or turbulence in the radar resolution volume. Physically reasonable momentum flux estimates are derived from the Reynolds stress components, which are also verified using a simple radar model incorporating GW-induced wind perturbations. On the basis of these results, we recommend the intercomparison of momentum flux estimates between co-located meteor radars and vertical-beam interferometric MF radars. It is envisaged that such intercomparisons will assist with the clarification of recent concerns (e.g. Vincent et al., 2010) of the accuracy of the meteor radar technique.

  10. Symmetric large momentum transfer for atom interferometry with BECs

    Science.gov (United States)

    Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Rasel, Ernst M.; Quantus Collaboration

    2017-04-01

    We develop and demonstrate a novel scheme for a symmetric large momentum transfer beam splitter for interferometry with Bose-Einstein condensates. Large momentum transfer beam splitters are a key technique to enhance the scaling factor and sensitivity of an atom interferometer and to create largely delocalized superposition states. To realize the beam splitter, double Bragg diffraction is used to create a superposition of two symmetric momentum states. Afterwards both momentum states are loaded into a retro-reflected optical lattice and accelerated by Bloch oscillations on opposite directions, keeping the initial symmetry. The favorable scaling behavior of this symmetric acceleration, allows to transfer more than 1000 ℏk of total differential splitting in a single acceleration sequence of 6 ms duration while we still maintain a fraction of approx. 25% of the initial atom number. As a proof of the coherence of this beam splitter, contrast in a closed Mach-Zehnder atom interferometer has been observed with up to 208 ℏk of momentum separation, which equals a differential wave-packet velocity of approx. 1.1 m/s for 87Rb. The presented work is supported by the CRC 1128 geo-Q and the DLR with funds provided by the Federal Ministry of Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under Grant No. DLR 50WM1552-1557 (QUANTUS-IV-Fallturm).

  11. Design of multichannel laser interferometry for W7-X

    International Nuclear Information System (INIS)

    Kornejew, P.; Hirsch, M.; Bindemann, T.; Dinklage, A.; Dreier, H.; Hartfuss, H.-J.

    2006-01-01

    An eight channel interferometer is developed for density feedback control and the continuous measurement of electron density profiles in the stellarator W7-X. An additional sightline is launched in the geometry of the Thomson scattering for cross calibration. Due to the W7-X coil geometry access is strongly restricted. This motivates the optimization of the sightline geometry and design studies for supplementary chords. In-vessel retroreflectors will be used and inserted in the first wall elements. To cope with associated mechanical vibrations and thermal drifts during the discharges with envisaged duration of 30 min either two-color or second harmonic interferometry techniques must be applied. Optimum wavelengths are found to be about 10 and 5 μm. A CO 2 /CO interferometer (10 μm/5 μm) will be tested and compared with an existing CO 2 /HeNe test interferometer. A special difficulty of remotely operated diagnostics is the need of long transmission lines with a path length of about 60 m required from the diagnostics location to the torus hall and back. Different arrangements will be compared

  12. Mapping Arctic Bottomfast Sea Ice Using SAR Interferometry

    Directory of Open Access Journals (Sweden)

    Dyre O. Dammann

    2018-05-01

    Full Text Available Bottomfast sea ice is an integral part of many near-coastal Arctic ecosystems with implications for subsea permafrost, coastal stability and morphology. Bottomfast sea ice is also of great relevance to over-ice travel by coastal communities, industrial ice roads, and marine habitats. There are currently large uncertainties around where and how much bottomfast ice is present in the Arctic due to the lack of effective approaches for detecting bottomfast sea ice on large spatial scales. Here, we suggest a robust method capable of detecting bottomfast sea ice using spaceborne synthetic aperture radar interferometry. This approach is used to discriminate between slowly deforming floating ice and completely stationary bottomfast ice based on the interferometric phase. We validate the approach over freshwater ice in the Mackenzie Delta, Canada, and over sea ice in the Colville Delta and Elson Lagoon, Alaska. For these areas, bottomfast ice, as interpreted from the interferometric phase, shows high correlation with local bathymetry and in-situ ice auger and ground penetrating radar measurements. The technique is further used to track the seasonal evolution of bottomfast ice in the Kasegaluk Lagoon, Alaska, by identifying freeze-up progression and areas of liquid water throughout winter.

  13. Wave-particle dualism in matter wave interferometry

    International Nuclear Information System (INIS)

    Rauch, H.

    1984-01-01

    Neutron interferometry is a unique tool for investigations in the field of particle-wave dualism because massive elementary particles behave like waves within the interferometer. The invention of perfect crystal neutron interferometers providing widely separated coherent beams stimulated a great variety of experiments with matter waves in the field of basic quantum mechanics. The phase of the spatial and spinor wave function become a measurable quantity and can be influenced individually. High degrees of coherence and high order interferences have been observed by this technique. The 4π-symmetry of a spinor wave function and the mutual modulation of nuclear and magnetic phase shifts have been measured in the past. Recent experiments dealt with polarized neutron beams, which are handled to realize the spin-superposition of two oppositionally polarized subbeams resulting in final polarization perpendicular to both initial beam polarizations. The different action on the coherent beams of static and dynamic flippers have been visualized. Monolithic multicrystal arrangements in Laue position can also be used to achieve an extremely high energy (10 -9 eV) or angular resolution (0.001 sec of arc). This feature is based on the Pendelloesung interference within the perfect crystal. A transverse coherence length up to 6.5 mm is deduced from single slit diffraction experiments. (Auth.)

  14. Sensitivity analysis of periodic errors in heterodyne interferometry

    International Nuclear Information System (INIS)

    Ganguly, Vasishta; Kim, Nam Ho; Kim, Hyo Soo; Schmitz, Tony

    2011-01-01

    Periodic errors in heterodyne displacement measuring interferometry occur due to frequency mixing in the interferometer. These nonlinearities are typically characterized as first- and second-order periodic errors which cause a cyclical (non-cumulative) variation in the reported displacement about the true value. This study implements an existing analytical periodic error model in order to identify sensitivities of the first- and second-order periodic errors to the input parameters, including rotational misalignments of the polarizing beam splitter and mixing polarizer, non-orthogonality of the two laser frequencies, ellipticity in the polarizations of the two laser beams, and different transmission coefficients in the polarizing beam splitter. A local sensitivity analysis is first conducted to examine the sensitivities of the periodic errors with respect to each input parameter about the nominal input values. Next, a variance-based approach is used to study the global sensitivities of the periodic errors by calculating the Sobol' sensitivity indices using Monte Carlo simulation. The effect of variation in the input uncertainty on the computed sensitivity indices is examined. It is seen that the first-order periodic error is highly sensitive to non-orthogonality of the two linearly polarized laser frequencies, while the second-order error is most sensitive to the rotational misalignment between the laser beams and the polarizing beam splitter. A particle swarm optimization technique is finally used to predict the possible setup imperfections based on experimentally generated values for periodic errors

  15. Sensitivity analysis of periodic errors in heterodyne interferometry

    Science.gov (United States)

    Ganguly, Vasishta; Kim, Nam Ho; Kim, Hyo Soo; Schmitz, Tony

    2011-03-01

    Periodic errors in heterodyne displacement measuring interferometry occur due to frequency mixing in the interferometer. These nonlinearities are typically characterized as first- and second-order periodic errors which cause a cyclical (non-cumulative) variation in the reported displacement about the true value. This study implements an existing analytical periodic error model in order to identify sensitivities of the first- and second-order periodic errors to the input parameters, including rotational misalignments of the polarizing beam splitter and mixing polarizer, non-orthogonality of the two laser frequencies, ellipticity in the polarizations of the two laser beams, and different transmission coefficients in the polarizing beam splitter. A local sensitivity analysis is first conducted to examine the sensitivities of the periodic errors with respect to each input parameter about the nominal input values. Next, a variance-based approach is used to study the global sensitivities of the periodic errors by calculating the Sobol' sensitivity indices using Monte Carlo simulation. The effect of variation in the input uncertainty on the computed sensitivity indices is examined. It is seen that the first-order periodic error is highly sensitive to non-orthogonality of the two linearly polarized laser frequencies, while the second-order error is most sensitive to the rotational misalignment between the laser beams and the polarizing beam splitter. A particle swarm optimization technique is finally used to predict the possible setup imperfections based on experimentally generated values for periodic errors.

  16. Detecting crack profile in concrete using digital image correlation and acoustic emission

    Directory of Open Access Journals (Sweden)

    Loukili A.

    2010-06-01

    Full Text Available Failure process in concrete structures is usually accompanied by cracking of concrete. Understanding the cracking pattern is very important while studying the failure governing criteria of concrete. The cracking phenomenon in concrete structures is usually complex and involves many microscopic mechanisms caused by material heterogeneity. Since last many years, fracture or damage analysis by experimental examinations of the cement based composites has shown importance to evaluate the cracking and damage behavior of those heterogeneous materials with damage accumulation due to microcracks development ahead of the propagating crack tip; and energy dissipation resulted during the evolution of damage in the structure. The techniques used in those experiments may be the holographic interferometry, the dye penetration, the scanning electron microscopy, the acoustic emission etc. Those methods offer either the images of the material surface to observe micro-features of the concrete with qualitative analysis, or the black-white fringe patterns of the deformation on the specimen surface, from which it is difficult to observe profiles of the damaged materials.

  17. Dynamic Corneal Surface Mapping with Electronic Speckle Pattern Interferometry

    Science.gov (United States)

    Iqbal, S.; Gualini, M. M. S.

    2013-06-01

    In view of the fast advancement in ophthalmic technology and corneal surgery, there is a strong need for the comprehensive mapping and characterization techniques for corneal surface. Optical methods with precision non-contact approaches have been found to be very useful for such bio measurements. Along with the normal mapping approaches, elasticity of corneal surface has an important role in its characterization and needs to be appropriately measured or estimated for broader diagnostics and better prospective surgical results, as it has important role in the post-op corneal surface reconstruction process. Use of normal corneal topographic devices is insufficient for any intricate analysis since these devices operate at relatively moderate resolution. In the given experiment, Pulsed Electronic Speckle Pattern Interferometry has been utilized along with an excitation mechanism to measure the dynamic response of the sample cornea. A Pulsed ESPI device has been chosen for the study because of its micron-level resolution and other advantages in real-time deformation analysis. A bovine cornea has been used as a sample in the subject experiment. The dynamic response has been taken on a chart recorder and it is observed that it does show a marked deformation at a specific excitation frequency, which may be taken as a characteristic elasticity parameter for the surface of that corneal sample. It was seen that outside resonance conditions the bovine cornea was not that much deformed. Through this study, the resonance frequency and the corresponding corneal deformations are mapped and plotted in real time. In these experiments, data was acquired and processed by FRAMES plus computer analysis system. With some analysis of the results, this technique can help us to refine a more detailed corneal surface mathematical model and some preliminary work was done on this. Such modelling enhancements may be useful for finer ablative surgery planning. After further experimentation

  18. Aero-acoustic Computations of Wind Turbines

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Michelsen, Jess; Sørensen, Jens Nørkær

    2002-01-01

    A numerical algorithm for acoustic noise generation is extended to 3D flows. The approach involves two parts comprising a viscous incompressible flow part and an inviscid acoustic part. In order to simulate noise generated from a wind turbine, the incompressible and acoustic equations are written...... in polar coordinates. The developed algorithm is combined with a so-called actuator-line technique in which the loading is distributed along lines representing the blade forces. Computations are carried out for the 500kW Nordtank wind turbine equipped with three LM19 blades. ©2001 The American Institute...

  19. Acoustic Parametric Array for Identifying Standoff Targets

    Science.gov (United States)

    Hinders, M. K.; Rudd, K. E.

    2010-02-01

    An integrated simulation method for investigating nonlinear sound beams and 3D acoustic scattering from any combination of complicated objects is presented. A standard finite-difference simulation method is used to model pulsed nonlinear sound propagation from a source to a scattering target via the KZK equation. Then, a parallel 3D acoustic simulation method based on the finite integration technique is used to model the acoustic wave interaction with the target. Any combination of objects and material layers can be placed into the 3D simulation space to study the resulting interaction. Several example simulations are presented to demonstrate the simulation method and 3D visualization techniques. The combined simulation method is validated by comparing experimental and simulation data and a demonstration of how this combined simulation method assisted in the development of a nonlinear acoustic concealed weapons detector is also presented.

  20. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... Facts What is acoustic neuroma? Diagnosing Symptoms Side Effects Keywords Questions to ask Choosing a healthcare provider ... Surgery What is acoustic neuroma Diagnosing Symptoms Side effects Question To Ask Treatment Options Back Overview Observation ...

  1. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... Facts What is acoustic neuroma? Diagnosing Symptoms Side Effects Keywords World Language Videos Questions to ask Choosing ... Surgery What is acoustic neuroma Diagnosing Symptoms Side effects Question To Ask Treatment Options Back Overview Observation ...

  2. Atlantic Herring Acoustic Surveys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Advanced Sampling Technologies Research Group conducts annual fisheries acoustic surveys using state-of-the-art acoustic, midwater trawling, and underwater...

  3. Tethys Acoustic Metadata Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Tethys database houses the metadata associated with the acoustic data collection efforts by the Passive Acoustic Group. These metadata include dates, locations...

  4. Free-solution, label-free molecular interactions studied by back-scattering interferometry

    DEFF Research Database (Denmark)

    Bornhop, D.J.; Latham, J.C.; Kussrow, A.

    2007-01-01

    Free-solution, label-free molecular interactions were investigated with back-scattering interferometry in a simple optical train composed of a helium-neon laser, a microfluidic channel, and a position sensor. Molecular binding interactions between proteins, ions and protein, and small molecules...... and protein, were determined with high dynamic range dissociation constants (K-d spanning six decades) and unmatched sensitivity (picomolar K-d's and detection limits of 10,000s of molecules). With this technique, equilibrium dissociation constants were quantified for protein A and immunoglobulin G...

  5. Measurement of Three-Dimensional Deformations by Phase-Shifting Digital Holographic Interferometry

    Directory of Open Access Journals (Sweden)

    Percival Almoro

    2003-06-01

    Full Text Available Out-of-plane deformations of a cantilever were measured using phase-shifting digital holographicinterferometry (PSDHI and the Fourier transform method (FTM. The cantilever was recorded in twodifferent states, and holograms were stored electronically with a charge-coupled device (CCD camera.When the holograms are superimposed and reconstructed jointly, a holographic interferogram results.The three-dimensional (3D surface deformations were successfully visualized by applying FTM toholographic interferogram analysis. The minimum surface displacement measured was 0.317 µm. Theprocessing time for the digital reconstruction and visualization of 3D deformation took about 1 minute.The technique was calibrated using Michelson interferometry setup.

  6. Full-field parallel interferometry coherence probe microscope for high-speed optical metrology.

    Science.gov (United States)

    Safrani, A; Abdulhalim, I

    2015-06-01

    Parallel detection of several achromatic phase-shifted images is used to obtain a high-speed, high-resolution, full-field, optical coherence probe tomography system based on polarization interferometry. The high enface imaging speed, short coherence gate, and high lateral resolution provided by the system are exploited to determine microbump height uniformity in an integrated semiconductor chip at 50 frames per second. The technique is demonstrated using the Linnik microscope, although it can be implemented on any polarization-based interference microscopy system.

  7. World Conference on Acoustic Emission 2013

    CERN Document Server

    Wu, Zhanwen; Zhang, Junjiao

    2015-01-01

    This volume collects the papers from the 2013 World Conference on Acoustic Emission in Shanghai. The latest research and applications of Acoustic Emission (AE) are explored, with particular emphasis on detecting and processing of AE signals, development of AE instrument and testing standards, AE of materials, engineering structures and systems, including the processing of collected data and analytical techniques as well as experimental case studies.

  8. World Conference on Acoustic Emission 2015

    CERN Document Server

    Wu, Zhanwen; Zhang, Junjiao

    2017-01-01

    This volume collects the papers from the World Conference on Acoustic Emission 2015 (WCAE-2015) in Hawaii. The latest research and applications of Acoustic Emission (AE) are explored, with particular emphasis on detecting and processing of AE signals, development of AE instrument and testing standards, AE of materials, engineering structures and systems, including the processing of collected data and analytical techniques as well as experimental case studies.

  9. An Optimisation Approach for Room Acoustics Design

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Kristian; Kirkegaard, Poul Henning; Andersen, Lars

    2005-01-01

    This paper discuss on a conceptual level the value of optimisation techniques in architectural acoustics room design from a practical point of view. It is chosen to optimise one objective room acoustics design criterium estimated from the sound field inside the room. The sound field is modeled...... using the boundary element method where absorption is incorporated. An example is given where the geometry of a room is defined by four design modes. The room geometry is optimised to get a uniform sound pressure....

  10. Tutorial on architectural acoustics

    Science.gov (United States)

    Shaw, Neil; Talaske, Rick; Bistafa, Sylvio

    2002-11-01

    This tutorial is intended to provide an overview of current knowledge and practice in architectural acoustics. Topics covered will include basic concepts and history, acoustics of small rooms (small rooms for speech such as classrooms and meeting rooms, music studios, small critical listening spaces such as home theatres) and the acoustics of large rooms (larger assembly halls, auditoria, and performance halls).

  11. Acoustic emission during hydrogen absorption and desorption in palladium

    International Nuclear Information System (INIS)

    Ramesh, R.; Mukhopadhyay, C.K.; Jayakumar, T.; Baldev Raj

    1996-01-01

    Acoustic emission technique has been used to study charging and discharging of hydrogen in palladium. During charging, breaking of oxide film due to surface activation and saturation of hydrogen absorption have been identified by acoustic emission. In the discharging cycle, the desorption of hydrogen from the specimen leads to high AE activity immediately after initiation of discharging, followed by gradual decrease in the acoustic activity, which reaches a minimum upon completion of the desorption. The potential of the acoustic emission technique for studying the kinetics of hydrogen absorption and desorption in metals has been shown. (author)

  12. A comparison of SONAH and IBEM for near-field acoustic holography

    DEFF Research Database (Denmark)

    Juhl, Peter Møller

    2008-01-01

    Among the popular techniques for acoustic source identification in complex environments are the Statistically Optimal Near Acoustic Holography (SONAH) and the Inverse Boundary Element Method (IBEM). These two methods are quite different regarding the underlying assumptions and the practical...

  13. Diffuse reflectance imaging for non-melanoma skin cancer detection using laser feedback interferometry

    Science.gov (United States)

    Mowla, Alireza; Taimre, Thomas; Lim, Yah L.; Bertling, Karl; Wilson, Stephen J.; Prow, Tarl W.; Soyer, H. P.; Rakić, Aleksandar D.

    2016-04-01

    We propose a compact, self-aligned, low-cost, and versatile infrared diffuse-reflectance laser imaging system using a laser feedback interferometry technique with possible applications in in vivo biological tissue imaging and skin cancer detection. We examine the proposed technique experimentally using a three-layer agar skin phantom. A cylindrical region with a scattering rate lower than that of the surrounding normal tissue was used as a model for a non-melanoma skin tumour. The same structure was implemented in a Monte Carlo computational model. The experimental results agree well with the Monte Carlo simulations validating the theoretical basis of the technique. Results prove the applicability of the proposed technique for biological tissue imaging, with the capability of depth sectioning and a penetration depth of well over 1.2 mm into the skin phantom.

  14. Classifying Particles By Acoustic Levitation

    Science.gov (United States)

    Barmatz, Martin B.; Stoneburner, James D.

    1983-01-01

    Separation technique well suited to material processing. Apparatus with rectangular-cross-section chamber used to measure equilibrium positions of low-density spheres in gravitational field. Vertical acoustic forces generated by two opposing compression drivers exciting fundamental plane-wave mode at 1.2 kHz. Additional horizontal drivers centered samples along vertical axis. Applications in fusion-target separation, biological separation, and manufacturing processes in liquid or gas media.

  15. Comparison of advanced optical imaging techniques with current otolaryngology diagnostics for improved middle ear assessment (Conference Presentation)

    Science.gov (United States)

    Nolan, Ryan M.; Shelton, Ryan L.; Monroy, Guillermo L.; Spillman, Darold R.; Novak, Michael A.; Boppart, Stephen A.

    2016-02-01

    Otolaryngologists utilize a variety of diagnostic techniques to assess middle ear health. Tympanometry, audiometry, and otoacoustic emissions examine the mobility of the tympanic membrane (eardrum) and ossicles using ear canal pressure and auditory tone delivery and detection. Laser Doppler vibrometry provides non-contact vibrational measurement, and acoustic reflectometry is used to assess middle ear effusion using sonar. These technologies and techniques have advanced the field beyond the use of the standard otoscope, a simple tissue magnifier, yet the need for direct visualization of middle ear disease for superior detection, assessment, and management remains. In this study, we evaluated the use of portable optical coherence tomography (OCT) and pneumatic low-coherence interferometry (LCI) systems with handheld probe delivery to standard tympanometry, audiometry, otoacoustic emissions, laser Doppler vibrometry, and acoustic reflectometry. Comparison of these advanced optical imaging techniques and current diagnostics was conducted with a case study subject with a history of unilateral eardrum trauma. OCT and pneumatic LCI provide novel dynamic spatiotemporal structural data of the middle ear, such as the thickness of the eardrum and quantitative detection of underlying disease pathology, which could allow for more accurate diagnosis and more appropriate management than currently possible.

  16. Cement paste surface roughness analysis using coherence scanning interferometry and confocal microscopy

    International Nuclear Information System (INIS)

    Apedo, K.L.; Munzer, C.; He, H.; Montgomery, P.; Serres, N.; Fond, C.; Feugeas, F.

    2015-01-01

    Scanning electron microscopy and scanning probe microscopy have been used for several decades to better understand the microstructure of cementitious materials. Very limited work has been performed to date to study the roughness of cementitious materials by optical microscopy such as coherence scanning interferometry (CSI) and chromatic confocal sensing (CCS). The objective of this paper is to better understand how CSI can be used as a tool to analyze surface roughness and topography of cement pastes. Observations from a series of images acquired using this technique on both polished and unpolished samples are described. The results from CSI are compared with those from a STIL confocal microscopy technique (SCM). Comparison between both optical techniques demonstrates the ability of CSI to measure both polished and unpolished cement pastes. - Highlights: • Coherence scanning interferometry (CSI) was used to analyze cement paste surfaces. • The results from the CSI were compared with those from a confocal microscopy. • 3D roughness parameters were obtained using the window resizing method. • Polished and unpolished cement pastes were studied

  17. Cement paste surface roughness analysis using coherence scanning interferometry and confocal microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Apedo, K.L., E-mail: apedo@unistra.fr [ICube, Université de Strasbourg, CNRS, 2 rue Boussingault, 67000 Strasbourg (France); Munzer, C.; He, H. [ICube, INSA de Strasbourg, CNRS, 24 Bld de la Victoire, 67084 Strasbourg (France); Montgomery, P. [ICube, Université de Strasbourg, CNRS, 23 rue du Loess, 67037 Strasbourg (France); Serres, N. [ICube, INSA de Strasbourg, CNRS, 24 Bld de la Victoire, 67084 Strasbourg (France); Fond, C. [ICube, Université de Strasbourg, CNRS, 2 rue Boussingault, 67000 Strasbourg (France); Feugeas, F. [ICube, INSA de Strasbourg, CNRS, 24 Bld de la Victoire, 67084 Strasbourg (France)

    2015-02-15

    Scanning electron microscopy and scanning probe microscopy have been used for several decades to better understand the microstructure of cementitious materials. Very limited work has been performed to date to study the roughness of cementitious materials by optical microscopy such as coherence scanning interferometry (CSI) and chromatic confocal sensing (CCS). The objective of this paper is to better understand how CSI can be used as a tool to analyze surface roughness and topography of cement pastes. Observations from a series of images acquired using this technique on both polished and unpolished samples are described. The results from CSI are compared with those from a STIL confocal microscopy technique (SCM). Comparison between both optical techniques demonstrates the ability of CSI to measure both polished and unpolished cement pastes. - Highlights: • Coherence scanning interferometry (CSI) was used to analyze cement paste surfaces. • The results from the CSI were compared with those from a confocal microscopy. • 3D roughness parameters were obtained using the window resizing method. • Polished and unpolished cement pastes were studied.

  18. Comparison of phase unwrapping algorithms for topography reconstruction based on digital speckle pattern interferometry

    Science.gov (United States)

    Li, Yuanbo; Cui, Xiaoqian; Wang, Hongbei; Zhao, Mengge; Ding, Hongbin

    2017-10-01

    Digital speckle pattern interferometry (DSPI) can diagnose the topography evolution in real-time, continuous and non-destructive, and has been considered as a most promising technique for Plasma-Facing Components (PFCs) topography diagnostic under the complicated environment of tokamak. It is important for the study of digital speckle pattern interferometry to enhance speckle patterns and obtain the real topography of the ablated crater. In this paper, two kinds of numerical model based on flood-fill algorithm has been developed to obtain the real profile by unwrapping from the wrapped phase in speckle interference pattern, which can be calculated through four intensity images by means of 4-step phase-shifting technique. During the process of phase unwrapping by means of flood-fill algorithm, since the existence of noise pollution, and other inevitable factors will lead to poor quality of the reconstruction results, this will have an impact on the authenticity of the restored topography. The calculation of the quality parameters was introduced to obtain the quality-map from the wrapped phase map, this work presents two different methods to calculate the quality parameters. Then quality parameters are used to guide the path of flood-fill algorithm, and the pixels with good quality parameters are given priority calculation, so that the quality of speckle interference pattern reconstruction results are improved. According to the comparison between the flood-fill algorithm which is suitable for speckle pattern interferometry and the quality-guided flood-fill algorithm (with two different calculation approaches), the errors which caused by noise pollution and the discontinuous of the strips were successfully reduced.

  19. Advanced Differential Radar Interferometry (A-DInSAR) as integrative tool for a structural geological analysis

    Science.gov (United States)

    Crippa, B.; Calcagni, L.; Rossi, G.; Sternai, P.

    2009-04-01

    Advanced Differential SAR interferometry (A-DInSAR) is a technique monitoring large-coverage surface deformations using a stack of interferograms generated from several complex SLC SAR images, acquired over the same target area at different times. In this work are described the results of a procedure to calculate terrain motion velocity on highly correlated pixels (E. Biescas, M. Crosetto, M. Agudo, O. Monserrat e B. Crippa: Two Radar Interferometric Approaches to Monitor Slow and Fast Land Deformation, 2007) in two area Gemona - Friuli, Northern Italy, Pollino - Calabria, Southern Italy, and, furthermore, are presented some consideration, based on successful examples of the present analysis. The choice of these pixels whose displacement velocity is calculated depends on the dispersion index value (DA) or using coherence values along the stack interferograms. A-DInSAR technique allows to obtain highly reliable velocity values of the vertical displacement. These values concern the movement of minimum surfaces of about 80m2 at the maximum resolution and the minimum velocity that can be recognized is of the order of mm/y. Because of the high versatility of the technology, because of the large dimensions of the area that can be analyzed (of about 10000Km2) and because of the high precision and reliability of the results obtained, we think it is possible to exploit radar interferometry to obtain some important information about the structural context of the studied area, otherwise very difficult to recognize. Therefore we propose radar interferometry as a valid investigation tool whose results must be considered as an important integration of the data collected in fieldworks.

  20. Nonlinear Acoustics

    Science.gov (United States)

    1974-02-14

    when 1 = 0, 5n - 0, ’Y is the ratio of specific heats, v the kinematic viscosity and v’ the thermometric conductivity. S is the cross sectional area of...particles of aluminum were suspended in a xylol filled glass cylinder. The circulatory nature is clearly indicated. In another technique, Zarembo and... aluminum (from Liebermann [ I I I). uses Eq. (3.49) for Uac, under the assumption that the cross sectional area of forward streaming is identical to the