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Sample records for acoustic signal analysis

  1. Acoustic emission and signal analysis

    NASA Astrophysics Data System (ADS)

    Rao, A. K.

    1990-01-01

    A review is given of the acoustic emission (AE) phenomenon and its applications in NDE and geological rock mechanics. Typical instrumentation used in AE signal detection, data acquisition, processing, and analysis is discussed. The parameters used in AE signal analysis are outlined, and current methods of AE signal analysis procedures are discussed. A literature review is presented on the pattern classification of AE signals. A discussion then follows on the application of AE in aircraft component monitoring, with an experiment described which focuses on in-flight AE monitoring during fatigue crack growth in an aero engine mount. A pattern recognition approach is detailed for the classification of the experimental data. The approach subjects each of the data files to a cluster analysis by the threshold-k-means scheme. The technique is shown to classify the data successfully.

  2. Pulse analysis of acoustic emission signals

    NASA Technical Reports Server (NTRS)

    Houghton, J. R.; Packman, P. F.

    1977-01-01

    A method for the signature analysis of pulses in the frequency domain and the time domain is presented. Fourier spectrum, Fourier transfer function, shock spectrum and shock spectrum ratio were examined in the frequency domain analysis, and pulse shape deconvolution was developed for use in the time domain analysis. Comparisons of the relative performance of each analysis technique are made for the characterization of acoustic emission pulses recorded by a measuring system. To demonstrate the relative sensitivity of each of the methods to small changes in the pulse shape, signatures of computer modeled systems with analytical pulses are presented. Optimization techniques are developed and used to indicate the best design parameters values for deconvolution of the pulse shape. Several experiments are presented that test the pulse signature analysis methods on different acoustic emission sources. These include acoustic emissions associated with: (1) crack propagation, (2) ball dropping on a plate, (3) spark discharge and (4) defective and good ball bearings. Deconvolution of the first few micro-seconds of the pulse train are shown to be the region in which the significant signatures of the acoustic emission event are to be found.

  3. Pulse analysis of acoustic emission signals

    NASA Technical Reports Server (NTRS)

    Houghton, J. R.; Packman, P. F.

    1977-01-01

    A method for the signature analysis of pulses in the frequency domain and the time domain is presented. Fourier spectrum, Fourier transfer function, shock spectrum and shock spectrum ratio were examined in the frequency domain analysis and pulse shape deconvolution was developed for use in the time domain analysis. Comparisons of the relative performance of each analysis technique are made for the characterization of acoustic emission pulses recorded by a measuring system. To demonstrate the relative sensitivity of each of the methods to small changes in the pulse shape, signatures of computer modeled systems with analytical pulses are presented. Optimization techniques are developed and used to indicate the best design parameter values for deconvolution of the pulse shape. Several experiments are presented that test the pulse signature analysis methods on different acoustic emission sources. These include acoustic emission associated with (a) crack propagation, (b) ball dropping on a plate, (c) spark discharge, and (d) defective and good ball bearings. Deconvolution of the first few micro-seconds of the pulse train is shown to be the region in which the significant signatures of the acoustic emission event are to be found.

  4. Wideband link-budget analysis for undersea acoustic signaling

    NASA Astrophysics Data System (ADS)

    Rice, Joseph A.; Hansen, Joseph T.

    2002-11-01

    Link-budget analysis is commonly applied to satellite and wireless communications for estimating the signal-to-noise ratio (SNR) at the receiver. Link-budget analysis considers transmitter power, transmitter antenna gain, channel losses, channel noise, and receiver antenna gain. For underwater signaling, the terms of the sonar equation readily translate to a formulation of the link budget. However, the strong frequency dependence of underwater acoustic propagation requires special consideration, and is represented as an intermediate result called the channel SNR. The channel SNR includes ambient-noise and transmission-loss components. Several acoustic communication and navigation problems are addressed through wideband link-budget analyses. [Work sponsored by ONR 321.

  5. Music Structure Analysis from Acoustic Signals

    NASA Astrophysics Data System (ADS)

    Dannenberg, Roger B.; Goto, Masataka

    Music is full of structure, including sections, sequences of distinct musical textures, and the repetition of phrases or entire sections. The analysis of music audio relies upon feature vectors that convey information about music texture or pitch content. Texture generally refers to the average spectral shape and statistical fluctuation, often reflecting the set of sounding instruments, e.g., strings, vocal, or drums. Pitch content reflects melody and harmony, which is often independent of texture. Structure is found in several ways. Segment boundaries can be detected by observing marked changes in locally averaged texture.

  6. Analysis of acoustic signals on welding and cutting

    SciTech Connect

    Morita, Takao; Ogawa, Yoji; Sumitomo, Takashi

    1995-12-31

    The sounds emitted during the welding and cutting processes are closely related to the processing phenomena, and sometimes they provide useful information for evaluation of their processing conditions. The analyses of acoustic signals from arc welding, plasma arc cutting, oxy-flame cutting, and water jet cutting are carried out in details in order to develop effective signal processing algorithm. The sound from TIG arc welding has the typical line spectrum which principal frequency, is almost the same as that of supplied electricity. The disturbance of welding process is clearly appeared oil the acoustic emission. The sound exposure level for CO{sub 2} or MIG welding is higher than that for TIG welding, and the relative intensity of the typical line spectrum caused by supplied electricity becomes low. But the sudden transition of welding condition oil produces an apparent change of sound exposure level. On the contrary, the acoustics from cutting processes are much louder than those of arc welding and show more chaotic behavior because the supplied fluid velocity and temperature of arc for cutting processes are much higher than those for welding processes. Therefore, it requires a special technique to extract the well meaning signals from the loud acoustic sounds. Further point of view, the reduction of acoustic exposure level becomes an important research theme with the growth of application fields of cutting processes.

  7. Pulse analysis of acoustic emission signals. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Houghton, J. R.

    1976-01-01

    A method for the signature analysis of pulses in the frequency domain and the time domain is presented. Fourier spectrum, Fourier transfer function, shock spectrum and shock spectrum ratio are examined in the frequency domain analysis, and pulse shape deconvolution is developed for use in the time domain analysis. To demonstrate the relative sensitivity of each of the methods to small changes in the pulse shape, signatures of computer modeled systems with analytical pulses are presented. Optimization techniques are developed and used to indicate the best design parameters values for deconvolution of the pulse shape. Several experiments are presented that test the pulse signature analysis methods on different acoustic emission sources. These include acoustic emissions associated with: (1) crack propagation, (2) ball dropping on a plate, (3) spark discharge and (4) defective and good ball bearings.

  8. Method of detection, classification, and identification of objects employing acoustic signal analysis

    NASA Astrophysics Data System (ADS)

    Orzanowski, Tomasz; Madura, Henryk; Sosnowski, Tomasz; Chmielewski, Krzysztof

    2008-10-01

    The methods of detection and identification of objects based on acoustic signal analysis are used in many applications, e.g., alarm systems, military battlefield reconnaissance systems, intelligent ammunition, and others. The construction of technical objects such as vehicle or helicopter gives some possibilities to identify them on the basis of acoustic signals generated by those objects. In this paper a method of automatic detection, classification and identification of military vehicles and helicopters using a digital analysis of acoustic signals is presented. The method offers a relatively high probability of object detection in attendance of other disturbing acoustic signals. Moreover, it provides low probability of false classification and identification of object. The application of this method to acoustic sensor for the anti-helicopter mine is also presented.

  9. Perceptually-driven signal analysis for acoustic event classification

    NASA Astrophysics Data System (ADS)

    Philips, Scott M.

    In many acoustic signal processing applications human listeners are able to outperform automated processing techniques, particularly in the identification and classification of acoustic events. The research discussed in this paper develops a framework for employing perceptual information from human listening experiments to improve automatic event classification. We focus on the identification of new signal attributes, or features, that are able to predict the human performance observed in formal listening experiments. Using this framework, our newly identified features have the ability to elevate automatic classification performance closer to the level of human listeners. We develop several new methods for learning a perceptual feature transform from human similarity measures. In addition to providing a more fundamental basis for uncovering perceptual features than previous approaches, these methods also lead to a greater insight into how humans perceive sounds in a dataset. We also develop a new approach for learning a perceptual distance metric. This metric is shown to be applicable to modern kernel-based techniques used in machine learning and provides a connection between the fields of psychoacoustics and machine learning. Our research demonstrates these new methods in the area of active sonar signal processing. There is anecdotal evidence within the sonar community that human operators are adept in the task of discriminating between active sonar target and clutter echoes. We confirm this ability in a series of formal listening experiments. With the results of these experiments, we then identify perceptual features and distance metrics using our novel methods. The results show better agreement with human performance than previous approaches. While this work demonstrates these methods using perceptual similarity measures from active sonar data, they are applicable to any similarity measure between signals.

  10. Empirical mode decomposition for analyzing acoustical signals

    NASA Technical Reports Server (NTRS)

    Huang, Norden E. (Inventor)

    2005-01-01

    The present invention discloses a computer implemented signal analysis method through the Hilbert-Huang Transformation (HHT) for analyzing acoustical signals, which are assumed to be nonlinear and nonstationary. The Empirical Decomposition Method (EMD) and the Hilbert Spectral Analysis (HSA) are used to obtain the HHT. Essentially, the acoustical signal will be decomposed into the Intrinsic Mode Function Components (IMFs). Once the invention decomposes the acoustic signal into its constituting components, all operations such as analyzing, identifying, and removing unwanted signals can be performed on these components. Upon transforming the IMFs into Hilbert spectrum, the acoustical signal may be compared with other acoustical signals.

  11. Synergy of seismic, acoustic, and video signals in blast analysis

    SciTech Connect

    Anderson, D.P.; Stump, B.W.; Weigand, J.

    1997-09-01

    The range of mining applications from hard rock quarrying to coal exposure to mineral recovery leads to a great variety of blasting practices. A common characteristic of many of the sources is that they are detonated at or near the earth`s surface and thus can be recorded by camera or video. Although the primary interest is in the seismic waveforms that these blasts generate, the visual observations of the blasts provide important constraints that can be applied to the physical interpretation of the seismic source function. In particular, high speed images can provide information on detonation times of individuals charges, the timing and amount of mass movement during the blasting process and, in some instances, evidence of wave propagation away from the source. All of these characteristics can be valuable in interpreting the equivalent seismic source function for a set of mine explosions and quantifying the relative importance of the different processes. This paper documents work done at the Los Alamos National Laboratory and Southern Methodist University to take standard Hi-8 video of mine blasts, recover digital images from them, and combine them with ground motion records for interpretation. The steps in the data acquisition, processing, display, and interpretation are outlined. The authors conclude that the combination of video with seismic and acoustic signals can be a powerful diagnostic tool for the study of blasting techniques and seismology. A low cost system for generating similar diagnostics using consumer-grade video camera and direct-to-disk video hardware is proposed. Application is to verification of the Comprehensive Test Ban Treaty.

  12. Acoustic cardiac signals analysis: a Kalman filter–based approach

    PubMed Central

    Salleh, Sheik Hussain; Hussain, Hadrina Sheik; Swee, Tan Tian; Ting, Chee-Ming; Noor, Alias Mohd; Pipatsart, Surasak; Ali, Jalil; Yupapin, Preecha P

    2012-01-01

    Auscultation of the heart is accompanied by both electrical activity and sound. Heart auscultation provides clues to diagnose many cardiac abnormalities. Unfortunately, detection of relevant symptoms and diagnosis based on heart sound through a stethoscope is difficult. The reason GPs find this difficult is that the heart sounds are of short duration and separated from one another by less than 30 ms. In addition, the cost of false positives constitutes wasted time and emotional anxiety for both patient and GP. Many heart diseases cause changes in heart sound, waveform, and additional murmurs before other signs and symptoms appear. Heart-sound auscultation is the primary test conducted by GPs. These sounds are generated primarily by turbulent flow of blood in the heart. Analysis of heart sounds requires a quiet environment with minimum ambient noise. In order to address such issues, the technique of denoising and estimating the biomedical heart signal is proposed in this investigation. Normally, the performance of the filter naturally depends on prior information related to the statistical properties of the signal and the background noise. This paper proposes Kalman filtering for denoising statistical heart sound. The cycles of heart sounds are certain to follow first-order Gauss–Markov process. These cycles are observed with additional noise for the given measurement. The model is formulated into state-space form to enable use of a Kalman filter to estimate the clean cycles of heart sounds. The estimates obtained by Kalman filtering are optimal in mean squared sense. PMID:22745550

  13. Development of an Acoustic Signal Analysis Tool “Auto-F” Based on the Temperament Scale

    NASA Astrophysics Data System (ADS)

    Modegi, Toshio

    The MIDI interface is originally designed for electronic musical instruments but we consider this music-note based coding concept can be extended for general acoustic signal description. We proposed applying the MIDI technology to coding of bio-medical auscultation sound signals such as heart sounds for retrieving medical records and performing telemedicine. Then we have tried to extend our encoding targets including vocal sounds, natural sounds and electronic bio-signals such as ECG, using Generalized Harmonic Analysis method. Currently, we are trying to separate vocal sounds included in popular songs and encode both vocal sounds and background instrumental sounds into separate MIDI channels. And also, we are trying to extract articulation parameters such as MIDI pitch-bend parameters in order to reproduce natural acoustic sounds using a GM-standard MIDI tone generator. In this paper, we present an overall algorithm of our developed acoustic signal analysis tool, based on those research works, which can analyze given time-based signals on the musical temperament scale. The prominent feature of this tool is producing high-precision MIDI codes, which reproduce the similar signals as the given source signal using a GM-standard MIDI tone generator, and also providing analyzed texts in the XML format.

  14. Multi-scale morphology analysis of acoustic emission signal and quantitative diagnosis for bearing fault

    NASA Astrophysics Data System (ADS)

    Wang, Wen-Jing; Cui, Ling-Li; Chen, Dao-Yun

    2016-04-01

    Monitoring of potential bearing faults in operation is of critical importance to safe operation of high speed trains. One of the major challenges is how to differentiate relevant signals to operational conditions of bearings from noises emitted from the surrounding environment. In this work, we report a procedure for analyzing acoustic emission signals collected from rolling bearings for diagnosis of bearing health conditions by examining their morphological pattern spectrum (MPS) through a multi-scale morphology analysis procedure. The results show that acoustic emission signals resulted from a given type of bearing faults share rather similar MPS curves. Further examinations in terms of sample entropy and Lempel-Ziv complexity of MPS curves suggest that these two parameters can be utilized to determine damage modes.

  15. Quadratic Time-Frequency Analysis of Hydroacoustic Signals as Applied to Acoustic Emissions of Large Whales

    NASA Astrophysics Data System (ADS)

    Le Bras, Ronan; Victor, Sucic; Damir, Malnar; Götz, Bokelmann

    2014-05-01

    In order to enrich the set of attributes in setting up a large database of whale signals, as envisioned in the Baleakanta project, we investigate methods of time-frequency analysis. The purpose of establishing the database is to increase and refine knowledge of the emitted signal and of its propagation characteristics, leading to a better understanding of the animal migrations in a non-invasive manner and to characterize acoustic propagation in oceanic media. The higher resolution for signal extraction and a better separation from other signals and noise will be used for various purposes, including improved signal detection and individual animal identification. The quadratic class of time-frequency distributions (TFDs) is the most popular set of time-frequency tools for analysis and processing of non-stationary signals. Two best known and most studied members of this class are the spectrogram and the Wigner-Ville distribution. However, to be used efficiently, i.e. to have highly concentrated signal components while significantly suppressing interference and noise simultaneously, TFDs need to be optimized first. The optimization method used in this paper is based on the Cross-Wigner-Ville distribution, and unlike similar approaches it does not require prior information on the analysed signal. The method is applied to whale signals, which, just like the majority of other real-life signals, can generally be classified as multicomponent non-stationary signals, and hence time-frequency techniques are a natural choice for their representation, analysis, and processing. We present processed data from a set containing hundreds of individual calls. The TFD optimization method results into a high resolution time-frequency representation of the signals. It allows for a simple extraction of signal components from the TFD's dominant ridges. The local peaks of those ridges can then be used for the signal components instantaneous frequency estimation, which in turn can be used as

  16. Detection of geodesic acoustic mode oscillations, using multiple signal classification analysis of Doppler backscattering signal on Tore Supra

    NASA Astrophysics Data System (ADS)

    Vermare, L.; Hennequin, P.; Gürcan, Ö. D.; the Tore Supra Team

    2012-06-01

    This paper presents the first observation of geodesic acoustic modes (GAMs) on Tore Supra plasmas. Using the Doppler backscattering system, the oscillations of the plasma flow velocity, localized between r/a = 0.85 and r/a = 0.95, and with a frequency, typically around 10 kHz, have been observed at the plasma edge in numerous discharges. When the additional heating power is varied, the frequency is found to scale with Cs/R. The MUltiple SIgnal Classification (MUSIC) algorithm is employed to access the temporal evolution of the perpendicular velocity of density fluctuations. The method is presented in some detail, and is validated and compared against standard methods, such as the conventional fast Fourier transform method, using a synthetic signal. It stands out as a powerful data analysis method to follow the Doppler frequency with a high temporal resolution, which is important in order to extract the dynamics of GAMs.

  17. Diagnostics of DC and Induction Motors Based on the Analysis of Acoustic Signals

    NASA Astrophysics Data System (ADS)

    Glowacz, A.

    2014-10-01

    In this paper, a non-invasive method of early fault diagnostics of electric motors was proposed. This method uses acoustic signals generated by electric motors. Essential features were extracted from acoustic signals of motors. A plan of study of acoustic signals of electric motors was proposed. Researches were carried out for faultless induction motor, induction motor with one faulty rotor bar, induction motor with two faulty rotor bars and flawless Direct Current, and Direct Current motor with shorted rotor coils. Researches were carried out for methods of signal processing: log area ratio coefficients, Multiple signal classification, Nearest Neighbor classifier and the Bayes classifier. A pattern creation process was carried out using 40 samples of sound. In the identification process 130 five-second test samples were used. The proposed approach will also reduce the costs of maintenance and the number of faulty motors in the industry.

  18. Amplitude-Frequency Analysis of Signals of Acoustic Emission from Granite Fractured at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Shcherbakov, I. P.; Chmel‧, A. E.

    2015-05-01

    The problem of stability of underground structures serving to store radioactive waste, to gasify carbon, and to utilize geothermal energy is associated with the action of elevated temperatures and pressures. The acoustic-emission method makes it possible to monitor the accumulation of microcracks arising in stress fields of both thermal and mechanical origin. In this report, the authors give results of a laboratory investigation into the acoustic emission from granite subjected to impact fracture at temperatures of up to 600°C. An amplitude-frequency analysis of acousticemission signals has enabled the authors to evaluate the dimension of the arising microcracks and to determine their character (intergranular or intragranular). It has been shown that intergranular faults on the boundaries between identical minerals predominate at room temperature (purely mechanical action); at a temperature of 300°C (impact plus thermoelastic stresses), there also appear cracks on the quartz-feldspar boundaries; finally, at temperatures of 500-600°C, it is intragranular faults that predominate in feldspar. The dimensions of the above three types of microcracks are approximately 2, 0.8, and 0.3 mm respectively.

  19. Efficient blind dereverberation and echo cancellation based on independent component analysis for actual acoustic signals.

    PubMed

    Takeda, Ryu; Nakadai, Kazuhiro; Takahashi, Toru; Komatani, Kazunori; Ogata, Tetsuya; Okuno, Hiroshi G

    2012-01-01

    This letter presents a new algorithm for blind dereverberation and echo cancellation based on independent component analysis (ICA) for actual acoustic signals. We focus on frequency domain ICA (FD-ICA) because its computational cost and speed of learning convergence are sufficiently reasonable for practical applications such as hands-free speech recognition. In applying conventional FD-ICA as a preprocessing of automatic speech recognition in noisy environments, one of the most critical problems is how to cope with reverberations. To extract a clean signal from the reverberant observation, we model the separation process in the short-time Fourier transform domain and apply the multiple input/output inverse-filtering theorem (MINT) to the FD-ICA separation model. A naive implementation of this method is computationally expensive, because its time complexity is the second order of reverberation time. Therefore, the main issue in dereverberation is to reduce the high computational cost of ICA. In this letter, we reduce the computational complexity to the linear order of the reverberation time by using two techniques: (1) a separation model based on the independence of delayed observed signals with MINT and (2) spatial sphering for preprocessing. Experiments show that the computational cost grows in proportion to the linear order of the reverberation time and that our method improves the word correctness of automatic speech recognition by 10 to 20 points in a RT₂₀= 670 ms reverberant environment. PMID:22023192

  20. Multi-bearing defect detection with trackside acoustic signal based on a pseudo time-frequency analysis and Dopplerlet filter

    NASA Astrophysics Data System (ADS)

    Zhang, Haibin; Lu, Siliang; He, Qingbo; Kong, Fanrang

    2016-03-01

    The diagnosis of train bearing defects based on the acoustic signal acquired by a trackside microphone plays a significant role in the transport system. However, the wayside acoustic signal suffers from the Doppler distortion due to the high moving speed and also contains the multi-source signals from different train bearings. This paper proposes a novel solution to overcome the two difficulties in trackside acoustic diagnosis. In the method a pseudo time-frequency analysis (PTFA) based on an improved Dopplerlet transform (IDT) is presented to acquire the time centers for different bearings. With the time centers, we design a series of Dopplerlet filters (DF) in time-frequency domain to work on the signal's time-frequency distribution (TFD) gained by the short time Fourier transform (STFT). Then an inverse STFT (ISTFT) is utilized to get the separated signals for each sound source which means bearing here. Later the resampling method based on certain motion parameters eliminates the Doppler Effect and finally the diagnosis can be made effectively according to the envelope spectrum of each separated signal. With the effectiveness of the technique validated by both simulated and experimental cases, the proposed wayside acoustic diagnostic scheme is expected to be available in wayside defective bearing detection.

  1. Acoustically-Induced Electrical Signals

    NASA Astrophysics Data System (ADS)

    Brown, S. R.

    2014-12-01

    We have observed electrical signals excited by and moving along with an acoustic pulse propagating in a sandstone sample. Using resonance we are now studying the characteristics of this acousto-electric signal and determining its origin and the controlling physical parameters. Four rock samples with a range of porosities, permeabilities, and mineralogies were chosen: Berea, Boise, and Colton sandstones and Austin Chalk. Pore water salinity was varied from deionized water to sea water. Ag-AgCl electrodes were attached to the sample and were interfaced to a 4-wire electrical resistivity system. Under computer control, the acoustic signals were excited and the electrical response was recorded. We see strong acoustically-induced electrical signals in all samples, with the magnitude of the effect for each rock getting stronger as we move from the 1st to the 3rd harmonics in resonance. Given a particular fluid salinity, each rock has its own distinct sensitivity in the induced electrical effect. For example at the 2nd harmonic, Berea Sandstone produces the largest electrical signal per acoustic power input even though Austin Chalk and Boise Sandstone tend to resonate with much larger amplitudes at the same harmonic. Two effects are potentially responsible for this acoustically-induced electrical response: one the co-seismic seismo-electric effect and the other a strain-induced resistivity change known as the acousto-electric effect. We have designed experimental tests to separate these mechanisms. The tests show that the seismo-electric effect is dominant in our studies. We note that these experiments are in a fluid viscosity dominated seismo-electric regime, leading to a simple interpretation of the signals where the electric potential developed is proportional to the local acceleration of the rock. Toward a test of this theory we have measured the local time-varying acoustic strain in our samples using a laser vibrometer.

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  3. Chelyabinsk meteoroid entry: analysis of acoustic signals in the area of direct sound propagation

    NASA Astrophysics Data System (ADS)

    Podobnaya, Elena; Popova, Olga; Glazachev, Dmitry; Rybnov, Yurij; Shuvalov, Valery; Jenniskens, Peter; Kharlamov, Vladimir

    E.Podobnaya, Yu.Rybnov, O.Popova, V. Shuvalov, P. Jenniskens, V.Kharlamov, D.Glazachev The Chelyabinsk airburst of 15 February 2013, was exceptional because of the large kinetic energy of the impacting body and the airburst that was generated, creating significant damage and injuries in a populated area. The meteor and the effects of the airburst were extraordinarily well documented. Numerous video records provided an accurate record of the trajectory and orbit of the cosmic body as well as features of its interaction with the atmosphere (Borovicka et al., 2013; Popova et al. 2013). In this presentation, we discuss the information on shock wave arrival times. Arrival times of the shock wave were derived from the shaking of the camera, the movement of smoke or car exhaust, and the movement of cables in the field of view, as well as directly from the audio record. From the analysis of these shock wave arrival times, the altitudes of the energy deposition were derived (Popova et al. 2013). Borovicka et al (2013) suggested that subsequent acoustic arrivals corresponded to separate fragmentation events. The observed arrival times will be compared with model estimates taking into account the real wind and atmospheric conditions (i.e. sound velocity changes with altitude). Results of numerical simulations will be compared with recorded sound signals. References Borovicka J. et al., 2013, Nature 503, 235 Popova O. et al., 2013, Science, 342, 1096

  4. Detection of Cracking Levels in Brittle Rocks by Parametric Analysis of the Acoustic Emission Signals

    NASA Astrophysics Data System (ADS)

    Moradian, Zabihallah; Einstein, Herbert H.; Ballivy, Gerard

    2016-03-01

    Determination of the cracking levels during the crack propagation is one of the key challenges in the field of fracture mechanics of rocks. Acoustic emission (AE) is a technique that has been used to detect cracks as they occur across the specimen. Parametric analysis of AE signals and correlating these parameters (e.g., hits and energy) to stress-strain plots of rocks let us detect cracking levels properly. The number of AE hits is related to the number of cracks, and the AE energy is related to magnitude of the cracking event. For a full understanding of the fracture process in brittle rocks, prismatic specimens of granite containing pre-existing flaws have been tested in uniaxial compression tests, and their cracking process was monitored with both AE and high-speed video imaging. In this paper, the characteristics of the AE parameters and the evolution of cracking sequences are analyzed for every cracking level. Based on micro- and macro-crack damage, a classification of cracking levels is introduced. This classification contains eight stages (1) crack closure, (2) linear elastic deformation, (3) micro-crack initiation (white patch initiation), (4) micro-crack growth (stable crack growth), (5) micro-crack coalescence (macro-crack initiation), (6) macro-crack growth (unstable crack growth), (7) macro-crack coalescence and (8) failure.

  5. Acoustic Localization with Infrasonic Signals

    NASA Astrophysics Data System (ADS)

    Threatt, Arnesha; Elbing, Brian

    2015-11-01

    Numerous geophysical and anthropogenic events emit infrasonic frequencies (<20 Hz), including volcanoes, hurricanes, wind turbines and tornadoes. These sounds, which cannot be heard by the human ear, can be detected from large distances (in excess of 100 miles) due to low frequency acoustic signals having a very low decay rate in the atmosphere. Thus infrasound could be used for long-range, passive monitoring and detection of these events. An array of microphones separated by known distances can be used to locate a given source, which is known as acoustic localization. However, acoustic localization with infrasound is particularly challenging due to contamination from other signals, sensitivity to wind noise and producing a trusted source for system development. The objective of the current work is to create an infrasonic source using a propane torch wand or a subwoofer and locate the source using multiple infrasonic microphones. This presentation will present preliminary results from various microphone configurations used to locate the source.

  6. Digital signal processing in acoustics. I

    NASA Astrophysics Data System (ADS)

    Davies, H.; McNeil, D. J.

    1985-11-01

    Digital signal processing techniques have gained steadily in importance over the past few years in many areas of science and engineering and have transformed the character of instrumentation used in laboratory and plant. This is particularly marked in acoustics, which has both benefited from the developments in signal processing and provided significant stimulus for these developments. As a result acoustical techniques are now used in a very wide range of applications and acoustics is one area in which digital signal processing is exploited to its limits. For example, the development of fast algorithms for computing Fourier transforms and the associated developments in hardware have led to remarkable advances in the use of spectral analysis as a means of investigating the nature and characteristics of acoustic sources. Speech research has benefited considerably in this respect, and, in a rather more technological application, spectral analysis of machinery noise provides information about changes in machine condition which may indicate imminent failure. More recently the observation that human and animal muscles emit low intensity noise suggests that spectral analysis of this noise may yield information about muscle structure and performance.

  7. Acoustic Data Processing and Transient Signal Analysis for the Hybrid Wing Body 14- by 22-Foot Subsonic Wind Tunnel Test

    NASA Technical Reports Server (NTRS)

    Bahr, Christopher J.; Brooks, Thomas F.; Humphreys, William M.; Spalt, Taylor B.; Stead, Daniel J.

    2014-01-01

    An advanced vehicle concept, the HWB N2A-EXTE aircraft design, was tested in NASA Langley's 14- by 22-Foot Subsonic Wind Tunnel to study its acoustic characteristics for var- ious propulsion system installation and airframe con gurations. A signi cant upgrade to existing data processing systems was implemented, with a focus on portability and a re- duction in turnaround time. These requirements were met by updating codes originally written for a cluster environment and transferring them to a local workstation while en- abling GPU computing. Post-test, additional processing of the time series was required to remove transient hydrodynamic gusts from some of the microphone time series. A novel automated procedure was developed to analyze and reject contaminated blocks of data, under the assumption that the desired acoustic signal of interest was a band-limited sta- tionary random process, and of lower variance than the hydrodynamic contamination. The procedure is shown to successfully identify and remove contaminated blocks of data and retain the desired acoustic signal. Additional corrections to the data, mainly background subtraction, shear layer refraction calculations, atmospheric attenuation and microphone directivity corrections, were all necessary for initial analysis and noise assessments. These were implemented for the post-processing of spectral data, and are shown to behave as expected.

  8. Acoustic signal processing toolbox for array processing

    NASA Astrophysics Data System (ADS)

    Pham, Tien; Whipps, Gene T.

    2003-08-01

    The US Army Research Laboratory (ARL) has developed an acoustic signal processing toolbox (ASPT) for acoustic sensor array processing. The intent of this document is to describe the toolbox and its uses. The ASPT is a GUI-based software that is developed and runs under MATLAB. The current version, ASPT 3.0, requires MATLAB 6.0 and above. ASPT contains a variety of narrowband (NB) and incoherent and coherent wideband (WB) direction-of-arrival (DOA) estimation and beamforming algorithms that have been researched and developed at ARL. Currently, ASPT contains 16 DOA and beamforming algorithms. It contains several different NB and WB versions of the MVDR, MUSIC and ESPRIT algorithms. In addition, there are a variety of pre-processing, simulation and analysis tools available in the toolbox. The user can perform simulation or real data analysis for all algorithms with user-defined signal model parameters and array geometries.

  9. Error surface topology in the data analysis of laser-induced thermal acoustics signals

    NASA Astrophysics Data System (ADS)

    Schlamp, Stefan; Schmid, Lukas

    2001-12-01

    Laser-induced thermal acoustics (LITA) promises remote, instantaneous and non-intrusive point-measurements of the speed of sound (temperature), thermal diffusivity (density), flow velocity (Mach number) and species concentration simultaneously in harsh environments. The data analysis relies on a nonlinear fit of an analytical model to the acquired data. The measured quantities are parameters in the model. Computational cost and convergence behaviour depend on the dimensionality of the parameter space, the initial guesses for the parameters and on whether the data analysis is performed in the time or frequency domain. The topology of the four-dimensional error surface is discussed and a characteristic allowable distance of the initial guesses from the global minimum is defined and quantified for typical configurations. Noise has no significant influence on the convergence neighbourhood or the computational cost. If improved initial guesses (10% maximum error) for the speed of sound and the flow velocity are obtained by data preprocessing, convergence of the fitting algorithm is ensured.

  10. In situ monitoring the pulse CO 2 laser interaction with 316-L stainless steel using acoustical signals and plasma analysis

    NASA Astrophysics Data System (ADS)

    Khosroshahi, M. E.; pour, F. Anoosheh; Hadavi, M.; Mahmoodi, M.

    2010-10-01

    In most laser material processing, material removal by different mechanisms is involved. Here, application of acoustic signals with thermoelastic (below threshold) and breakdown origin (above threshold) together with plasma plume analysis as a simple monitoring system of interaction process is suggested. In this research the interaction of pulse CO 2 laser with 200 ns duration and maximum energy of 1.3 J operating at 1 Hz with austenitic stainless steel (316-L) is reported. The results showed that the non-linear point of the curve can serve as a useful indicator of melting fluence threshold (in this case ≈830 J cm -2) with corresponding temperature calculated using plasma plume analysis. Higher acoustic amplitudes and larger plasma plume volume indicates more intense interaction. Also, analysis showed that a phase explosion process with material removal (ejecta) in the form of non-adiabatic (i.e., dt ≫ α-1) is at play after laser pulse is ended. Also, SEM photographs show different surface quality medication at different laser intensities, which indicates the importance of recoil momentum pressure and possibly electrons and ions densities in heat transfer. Finally, electrochemical test indicate an improved corrosion resistance for laser treated samples compared to untreated ones.

  11. Signal Analysis of Helicopter Blade-Vortex-Interaction Acoustic Noise Data

    NASA Technical Reports Server (NTRS)

    Rogers, James C.; Dai, Renshou

    1998-01-01

    Blade-Vortex-Interaction (BVI) produces annoying high-intensity impulsive noise. NASA Ames collected several sets of BVI noise data during in-flight and wind tunnel tests. The goal of this work is to extract the essential features of the BVI signals from the in-flight data and examine the feasibility of extracting those features from BVI noise recorded inside a large wind tunnel. BVI noise generating mechanisms and BVI radiation patterns an are considered and a simple mathematical-physical model is presented. It allows the construction of simple synthetic BVI events that are comparable to free flight data. The boundary effects of the wind tunnel floor and ceiling are identified and more complex synthetic BVI events are constructed to account for features observed in the wind tunnel data. It is demonstrated that improved recording of BVI events can be attained by changing the geometry of the rotor hub, floor, ceiling and microphone. The Euclidean distance measure is used to align BVI events from each blade and improved BVI signals are obtained by time-domain averaging the aligned data. The differences between BVI events for individual blades are then apparent. Removal of wind tunnel background noise by optimal Wiener-filtering is shown to be effective provided representative noise-only data have been recorded. Elimination of wind tunnel reflections by cepstral and optimal filtering deconvolution is examined. It is seen that the cepstral method is not applicable but that a pragmatic optimal filtering approach gives encouraging results. Recommendations for further work include: altering measurement geometry, real-time data observation and evaluation, examining reflection signals (particularly those from the ceiling) and performing further analysis of expected BVI signals for flight conditions of interest so that microphone placement can be optimized for each condition.

  12. Perturbation and Nonlinear Dynamic Analysis of Acoustic Phonatory Signal in Parkinsonian Patients Receiving Deep Brain Stimulation

    ERIC Educational Resources Information Center

    Lee, Victoria S.; Zhou, Xiao Ping; Rahn, Douglas A., III; Wang, Emily Q.; Jiang, Jack J.

    2008-01-01

    Nineteen PD patients who received deep brain stimulation (DBS), 10 non-surgical (control) PD patients, and 11 non-pathologic age- and gender-matched subjects performed sustained vowel phonations. The following acoustic measures were obtained on the sustained vowel phonations: correlation dimension (D[subscript 2]), percent jitter, percent shimmer,…

  13. Acoustic signal propagation characterization of conduit networks

    NASA Astrophysics Data System (ADS)

    Khan, Muhammad Safeer

    Analysis of acoustic signal propagation in conduit networks has been an important area of research in acoustics. One major aspect of analyzing conduit networks as acoustic channels is that a propagating signal suffers frequency dependent attenuation due to thermo-viscous boundary layer effects and the presence of impedance mismatches such as side branches. The signal attenuation due to side branches is strongly influenced by their numbers and dimensions such as diameter and length. Newly developed applications for condition based monitoring of underground conduit networks involve measurement of acoustic signal attenuation through tests in the field. In many cases the exact installation layout of the field measurement location may not be accessible or actual installation may differ from the documented layout. The lack of exact knowledge of numbers and lengths of side branches, therefore, introduces uncertainty in the measurements of attenuation and contributes to the random variable error between measured results and those predicted from theoretical models. There are other random processes in and around conduit networks in the field that also affect the propagation of an acoustic signal. These random processes include but are not limited to the presence of strong temperature and humidity gradients within the conduits, blockages of variable sizes and types, effects of aging such as cracks, bends, sags and holes, ambient noise variations and presence of variable layer of water. It is reasonable to consider that the random processes contributing to the error in the measured attenuation are independent and arbitrarily distributed. The error, contributed by a large number of independent sources of arbitrary probability distributions, is best described by an approximately normal probability distribution in accordance with the central limit theorem. Using an analytical approach to model the attenuating effect of each of the random variable sources can be very complex and

  14. Acoustic-Seismic Coupling of Broadband Signals - Analysis of Potential Disturbances during CTBT On-Site Inspection Measurements

    NASA Astrophysics Data System (ADS)

    Liebsch, Mattes; Altmann, Jürgen

    2015-04-01

    For the verification of the Comprehensive Nuclear Test Ban Treaty (CTBT) the precise localisation of possible underground nuclear explosion sites is important. During an on-site inspection (OSI) sensitive seismic measurements of aftershocks can be performed, which, however, can be disturbed by other signals. To improve the quality and effectiveness of these measurements it is essential to understand those disturbances so that they can be reduced or prevented. In our work we focus on disturbing signals caused by airborne sources: When the sound of aircraft (as often used by the inspectors themselves) hits the ground, it propagates through pores in the soil. Its energy is transferred to the ground and soil vibrations are created which can mask weak aftershock signals. The understanding of the coupling of acoustic waves to the ground is still incomplete. However, it is necessary to improve the performance of an OSI, e.g. to address potential consequences for the sensor placement, the helicopter trajectories etc. We present our recent advances in this field. We performed several measurements to record sound pressure and soil velocity produced by various sources, e.g. broadband excitation by jet aircraft passing overhead and signals artificially produced by a speaker. For our experimental set-up microphones were placed close to the ground and geophones were buried in different depths in the soil. Several sensors were shielded from the directly incident acoustic signals by a box coated with acoustic damping material. While sound pressure under the box was strongly reduced, the soil velocity measured under the box was just slightly smaller than outside of it. Thus these soil vibrations were mostly created outside the box and travelled through the soil to the sensors. This information is used to estimate characteristic propagation lengths of the acoustically induced signals in the soil. In the seismic data we observed interference patterns which are likely caused by the

  15. Signal Analysis Algorithms for Optimized Fitting of Nonresonant Laser Induced Thermal Acoustics Damped Sinusoids

    NASA Technical Reports Server (NTRS)

    Balla, R. Jeffrey; Miller, Corey A.

    2008-01-01

    This study seeks a numerical algorithm which optimizes frequency precision for the damped sinusoids generated by the nonresonant LITA technique. It compares computed frequencies, frequency errors, and fit errors obtained using five primary signal analysis methods. Using variations on different algorithms within each primary method, results from 73 fits are presented. Best results are obtained using an AutoRegressive method. Compared to previous results using Prony s method, single shot waveform frequencies are reduced approx.0.4% and frequency errors are reduced by a factor of approx.20 at 303K to approx. 0.1%. We explore the advantages of high waveform sample rates and potential for measurements in low density gases.

  16. Traceability of Acoustic Emission measurements for a proposed calibration method - Classification of characteristics and identification using signal analysis

    NASA Astrophysics Data System (ADS)

    Griffin, James

    2015-01-01

    When using Acoustic Emission (AE) technologies, tensile, compressive and shear stress/strain tests can provide a detector for material deformation and dislocations. In this paper improvements are made to standardise calibration techniques for AE against known metrics such as force. AE signatures were evaluated from various calibration energy sources based on the energy from the first harmonic (dominant energy band) [1,2]. The effects of AE against its calibration identity are investigated: where signals are correlated to the average energy and distance of the detected phenomena. In addition, extra tests are investigated in terms of the tensile tests and single grit tests characterising different materials. Necessary translations to the time-frequency domain were necessary when segregating salient features between different material properties. Continuing this work the obtained AE is summarised and evaluated by a Neural Network (NN) regression classification technique which identifies how far the malformation has progressed (in terms of energy/force) during material transformation. Both genetic-fuzzy clustering and tree rule based classifier techniques were used as the second and third classification techniques respectively to verify the NN output giving a weighted three classifier system. The work discussed in this paper looks at both distance and force relationships for various prolonged Acoustic Emission stresses. Later such analysis was realised with different classifier models and finally implemented into the Simulink simulations. Further investigations were made into classifier models for different material interactions in terms of force and distance which add further dimension to this work with different materials based simulation realisations. Within the statistical analysis section there are two varying prolonged stress tests which together offer the mechanical calibration system (automated solenoid and pencil break calibration system). Taking such a

  17. Study of acoustic emission sources and signals

    NASA Astrophysics Data System (ADS)

    Pumarega, M. I. López; Armeite, M.; Oliveto, M. E.; Piotrkowski, R.; Ruzzante, J. E.

    2002-05-01

    Methods of acoustic emission (AE) signal analysis give information about material conditions, since AE generated in stressed solids can be used to indicate cracks and defect positions so as their damaging potential. We present a review of results of laboratory AE tests on metallic materials. Rings of seamless steel tubes, with and without oxide layers, were cut and then deformed by opening their ends. Seamless Zry-4 tubes were submitted to hydraulic stress tests until rupture with a purposely-constructed hydraulic system. In burst type signals, their parameters, Amplitude (A), Duration (D) and Risetime (R), were statistically studied. Amplitudes were found to follow the Log-normal distribution. This led to infer that the detected AE signal, is the complex consequence of a great number of random independent sources, which individual effects are linked. We could show, using cluster analysis for A, D and R mean values, with 5 clusters, coincidence between the clusters and the test types. A slight linear correlation was obtained for the parameters A and D. The arrival time of the AE signals was also studied, which conducted to discussing Poisson and Polya processes. The digitized signals were studied as (1/f)β noises. The general results are coherent if we consider the AE phenomena in the frame of Self Organized Criticality theory.

  18. [Analysis of species specific acoustic signals in the mesencephalic, diencephalic, and neostriatal structures of the brain].

    PubMed

    Shliafer, T P; Aleksandrova, Zh G

    1979-10-01

    In chronic experiments, the neuronal activity in structures of the auditory analyzer was studied during perception of species-specific signals in the chicken. The majority of the neostriatum cells responded to territorial vocalizations of the rooster and to squeaking of the chicken; in the midbrain structures the maximal responses occurred to signals of distress and alarm. The greatest number of cells responded most obviously to the cardinal component of the chicken vocalization spectrum. PMID:510592

  19. Spatial acoustic signal processing for immersive communication

    NASA Astrophysics Data System (ADS)

    Atkins, Joshua

    Computing is rapidly becoming ubiquitous as users expect devices that can augment and interact naturally with the world around them. In these systems it is necessary to have an acoustic front-end that is able to capture and reproduce natural human communication. Whether the end point is a speech recognizer or another human listener, the reduction of noise, reverberation, and acoustic echoes are all necessary and complex challenges. The focus of this dissertation is to provide a general method for approaching these problems using spherical microphone and loudspeaker arrays.. In this work, a theory of capturing and reproducing three-dimensional acoustic fields is introduced from a signal processing perspective. In particular, the decomposition of the spatial part of the acoustic field into an orthogonal basis of spherical harmonics provides not only a general framework for analysis, but also many processing advantages. The spatial sampling error limits the upper frequency range with which a sound field can be accurately captured or reproduced. In broadband arrays, the cost and complexity of using multiple transducers is an issue. This work provides a flexible optimization method for determining the location of array elements to minimize the spatial aliasing error. The low frequency array processing ability is also limited by the SNR, mismatch, and placement error of transducers. To address this, a robust processing method is introduced and used to design a reproduction system for rendering over arbitrary loudspeaker arrays or binaurally over headphones. In addition to the beamforming problem, the multichannel acoustic echo cancellation (MCAEC) issue is also addressed. A MCAEC must adaptively estimate and track the constantly changing loudspeaker-room-microphone response to remove the sound field presented over the loudspeakers from that captured by the microphones. In the multichannel case, the system is overdetermined and many adaptive schemes fail to converge to

  20. A signal processing approach for enhanced Acoustic Emission data analysis in high activity systems: Application to organic matrix composites

    NASA Astrophysics Data System (ADS)

    Kharrat, M.; Ramasso, E.; Placet, V.; Boubakar, M. L.

    2016-03-01

    Structural elements made of Organic Matrix Composites (OMC) under complex loading may suffer from high Acoustic Emission (AE) activity caused by the emergence of different emission sources at high rates with high noise level, which finally engender continuous emissions. The detection of hits in this situation becomes a challenge particularly during fatigue tests. This work suggests an approach based on the Discrete Wavelet Transform (DWT) denoising applied on signal segments. A particular attention is paid to the adjustment of the denoising parameters based on pencil lead breaks and their influence on the quality of the denoised AE signals. The validation of the proposed approach is performed on a ring-shaped Carbon Fiber Reinforced Plastics (CFRP) under in-service-like conditions involving continuous emissions with superimposed damage-related transients. It is demonstrated that errors in hit detection are greatly reduced leading to a better identification of the natural damage scenario based on AE signals.

  1. Wavelet-based ground vehicle recognition using acoustic signals

    NASA Astrophysics Data System (ADS)

    Choe, Howard C.; Karlsen, Robert E.; Gerhart, Grant R.; Meitzler, Thomas J.

    1996-03-01

    We present, in this paper, a wavelet-based acoustic signal analysis to remotely recognize military vehicles using their sound intercepted by acoustic sensors. Since expedited signal recognition is imperative in many military and industrial situations, we developed an algorithm that provides an automated, fast signal recognition once implemented in a real-time hardware system. This algorithm consists of wavelet preprocessing, feature extraction and compact signal representation, and a simple but effective statistical pattern matching. The current status of the algorithm does not require any training. The training is replaced by human selection of reference signals (e.g., squeak or engine exhaust sound) distinctive to each individual vehicle based on human perception. This allows a fast archiving of any new vehicle type in the database once the signal is collected. The wavelet preprocessing provides time-frequency multiresolution analysis using discrete wavelet transform (DWT). Within each resolution level, feature vectors are generated from statistical parameters and energy content of the wavelet coefficients. After applying our algorithm on the intercepted acoustic signals, the resultant feature vectors are compared with the reference vehicle feature vectors in the database using statistical pattern matching to determine the type of vehicle from where the signal originated. Certainly, statistical pattern matching can be replaced by an artificial neural network (ANN); however, the ANN would require training data sets and time to train the net. Unfortunately, this is not always possible for many real world situations, especially collecting data sets from unfriendly ground vehicles to train the ANN. Our methodology using wavelet preprocessing and statistical pattern matching provides robust acoustic signal recognition. We also present an example of vehicle recognition using acoustic signals collected from two different military ground vehicles. In this paper, we will

  2. Semi-real-time monitoring of cracking on couplings by neural network analysis of acoustic emission signals

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

    This paper presents the results obtained during the development of a semi-real-time monitoring methodology based on Neural Network Pattern Recognition of Acoustic Emission (AE) signals for early detection of cracks in couplings used in aircraft and engine drive systems. AE signals were collected in order to establish a baseline of a gear-testing fixture background noise and its variations due to rotational speed and torque. Also, simulated cracking signals immersed in background noise were collected. EDM notches were machined in the driving gear and the load on the gearbox was increased until damaged was induced. Using these data, a Neural Network Signal Classifier (NNSC) was implemented and tested. The testing showed that the NNSC was capable of correctly identifying six different classes of AE signals corresponding to different gearbox operation conditions. Also, a semi-real-time classification software was implemented. This software includes functions that allow the user to view and classify AE data from a dynamic process as they are recorded at programmable time intervals. The software is capable of monitoring periodic statistics of AE data, which can be used as an indicator of damage presence and severity in a dynamic system. The semi-real-time classification software was successfully tested in situations where a delay of 10 seconds between data acquisition and classification was achieved with a hit rate of 50 hits/second per channel on eight active AE channels.

  3. Ice breakup: Observations of the acoustic signal

    NASA Astrophysics Data System (ADS)

    Waddell, S. R.; Farmer, D. M.

    1988-03-01

    We describe observations of ambient sound beneath landfast ice in the Canadian Arctic Archipelago and interpret its evolution over the period June-August in terms of ice cracking and disintegration. The data were recorded on six bands between 50 and 14,500 Hz for the period April 2 to August 7, 1986, in Dolphin and Union Strait. The frequency dependence of the attenuation of sound in water allows separation of distant and local noise sources. In conjunction with satellite imagery and meteorological data, it is shown that strong signals in the acoustic time series are associated with major breakup events. The acoustic signal can provide predictive information about ice conditions and the approach of breakup.

  4. Detection and Classification of Whale Acoustic Signals

    NASA Astrophysics Data System (ADS)

    Xian, Yin

    This dissertation focuses on two vital challenges in relation to whale acoustic signals: detection and classification. In detection, we evaluated the influence of the uncertain ocean environment on the spectrogram-based detector, and derived the likelihood ratio of the proposed Short Time Fourier Transform detector. Experimental results showed that the proposed detector outperforms detectors based on the spectrogram. The proposed detector is more sensitive to environmental changes because it includes phase information. In classification, our focus is on finding a robust and sparse representation of whale vocalizations. Because whale vocalizations can be modeled as polynomial phase signals, we can represent the whale calls by their polynomial phase coefficients. In this dissertation, we used the Weyl transform to capture chirp rate information, and used a two dimensional feature set to represent whale vocalizations globally. Experimental results showed that our Weyl feature set outperforms chirplet coefficients and MFCC (Mel Frequency Cepstral Coefficients) when applied to our collected data. Since whale vocalizations can be represented by polynomial phase coefficients, it is plausible that the signals lie on a manifold parameterized by these coefficients. We also studied the intrinsic structure of high dimensional whale data by exploiting its geometry. Experimental results showed that nonlinear mappings such as Laplacian Eigenmap and ISOMAP outperform linear mappings such as PCA and MDS, suggesting that the whale acoustic data is nonlinear. We also explored deep learning algorithms on whale acoustic data. We built each layer as convolutions with either a PCA filter bank (PCANet) or a DCT filter bank (DCTNet). With the DCT filter bank, each layer has different a time-frequency scale representation, and from this, one can extract different physical information. Experimental results showed that our PCANet and DCTNet achieve high classification rate on the whale

  5. Identifying Potential Noise Sources within Acoustic Signals

    NASA Astrophysics Data System (ADS)

    Holcomb, Victoria; Lewalle, Jacques

    2013-11-01

    We test a new algorithm for its ability to detect sources of noise within random background. The goal of these tests is to better understand how to identify sources within acoustic signals while simultaneously determining the strengths and weaknesses of the algorithm in question. Unlike previously published algorithms, the antenna method does not pinpoint events by looking for the most energetic portions of a signal. The algorithm searches for the ideal lag combinations between three signals by taking excerpts of possible events. The excerpt with the lowest calculated minimum distance between possible events is how the algorithm identifies sources. At the minimum distance, the events are close in time and frequency. This method can be compared to the cross correlation and denoising methods to better understand its effectiveness. This work is supported in part by Spectral Energies LLC, under an SBIR grant from AFRL, as well as the Syracuse University MAE department.

  6. Bird population density estimated from acoustic signals

    USGS Publications Warehouse

    Dawson, D.K.; Efford, M.G.

    2009-01-01

    Many animal species are detected primarily by sound. Although songs, calls and other sounds are often used for population assessment, as in bird point counts and hydrophone surveys of cetaceans, there are few rigorous methods for estimating population density from acoustic data. 2. The problem has several parts - distinguishing individuals, adjusting for individuals that are missed, and adjusting for the area sampled. Spatially explicit capture-recapture (SECR) is a statistical methodology that addresses jointly the second and third parts of the problem. We have extended SECR to use uncalibrated information from acoustic signals on the distance to each source. 3. We applied this extension of SECR to data from an acoustic survey of ovenbird Seiurus aurocapilla density in an eastern US deciduous forest with multiple four-microphone arrays. We modelled average power from spectrograms of ovenbird songs measured within a window of 0??7 s duration and frequencies between 4200 and 5200 Hz. 4. The resulting estimates of the density of singing males (0??19 ha -1 SE 0??03 ha-1) were consistent with estimates of the adult male population density from mist-netting (0??36 ha-1 SE 0??12 ha-1). The fitted model predicts sound attenuation of 0??11 dB m-1 (SE 0??01 dB m-1) in excess of losses from spherical spreading. 5.Synthesis and applications. Our method for estimating animal population density from acoustic signals fills a gap in the census methods available for visually cryptic but vocal taxa, including many species of bird and cetacean. The necessary equipment is simple and readily available; as few as two microphones may provide adequate estimates, given spatial replication. The method requires that individuals detected at the same place are acoustically distinguishable and all individuals vocalize during the recording interval, or that the per capita rate of vocalization is known. We believe these requirements can be met, with suitable field methods, for a significant

  7. Acoustic Gaits: Gait Analysis With Footstep Sounds.

    PubMed

    Altaf, M Umair Bin; Butko, Taras; Juang, Biing-Hwang Fred

    2015-08-01

    We describe the acoustic gaits-the natural human gait quantitative characteristics derived from the sound of footsteps as the person walks normally. We introduce the acoustic gait profile, which is obtained from temporal signal analysis of sound of footsteps collected by microphones and illustrate some of the spatio-temporal gait parameters that can be extracted from the acoustic gait profile by using three temporal signal analysis methods-the squared energy estimate, Hilbert transform and Teager-Kaiser energy operator. Based on the statistical analysis of the parameter estimates, we show that the spatio-temporal parameters and gait characteristics obtained using the acoustic gait profile can consistently and reliably estimate a subset of clinical and biometric gait parameters currently in use for standardized gait assessments. We conclude that the Teager-Kaiser energy operator provides the most consistent gait parameter estimates showing the least variation across different sessions and zones. Acoustic gaits use an inexpensive set of microphones with a computing device as an accurate and unintrusive gait analysis system. This is in contrast to the expensive and intrusive systems currently used in laboratory gait analysis such as the force plates, pressure mats and wearable sensors, some of which may change the gait parameters that are being measured. PMID:25769144

  8. Acoustic signals generated in inclined granular flows

    NASA Astrophysics Data System (ADS)

    Tan, Danielle S.; Jenkins, James T.; Keast, Stephen C.; Sachse, Wolfgang H.

    2015-10-01

    Spontaneous avalanching in specific deserts produces a low-frequency sound known as "booming." This creates a puzzle, because avalanches down the face of a dune result in collisions between sand grains that occur at much higher frequencies. Reproducing this phenomenon in the laboratory permits a better understanding of the underlying mechanisms for the generation of such lower frequency acoustic emissions, which may also be relevant to other dry granular flows. Here we report measurements of low-frequency acoustical signals, produced by dried "sounding" sand (sand capable of booming in the desert) flowing down an inclined chute. The amplitude of the signal diminishes over time but reappears upon drying of the sand. We show that the presence of this sound in the experiments may provide supporting evidence for a previously published "waveguide" explanation for booming. Also, we propose a model based on kinetic theory for a sheared inclined flow in which the flowing layer exhibits "breathing" modes superimposed on steady shearing. The predicted oscillation frequency is of a similar order of magnitude as the measurements, indicating that small perturbations can sustain oscillations of a low frequency. However, the frequency is underestimated, which indicates that the stiffness has been underestimated. Also, the model predicts a discrete spectrum of frequencies, instead of the broadband spectrum measured experimentally.

  9. Laser-induced thermal acoustics (LITA) signals from finite beams

    NASA Astrophysics Data System (ADS)

    Cummings, E. B.; Leyva, I. A.; Hornung, H. G.

    1995-06-01

    Laser-induced thermal acoustics (LITA) is a four-wave mixing technique that may be employed to measure sound speeds, transport properties, velocities, and susceptibilities of fluids. It is particularly effective in high-pressure gases ( greater than 1 bar). An analytical expression for LITA signals is derived by the use of linearized equations of hydrodynamics and light scattering. This analysis, which includes full finite-beam-size effects and the optoacoustic effects of thermalization and electrostriction, predicts the amplitude and the time history of narrow-band time-resolved LITA and broadband spectrally resolved (mulitplex) LITA signals. The time behavior of the detected LITA signal depends significantly on the detection solid angle, with implications for the measurement of diffusivities by the use of LITA and the proper physical picture of LITA scattering. This and other elements of the physics of LITA that emerge from the analysis are discussed. Theoretical signals are compared with experimental LITA data.

  10. Acoustic signal detection of manatee calls

    NASA Astrophysics Data System (ADS)

    Niezrecki, Christopher; Phillips, Richard; Meyer, Michael; Beusse, Diedrich O.

    2003-04-01

    The West Indian manatee (trichechus manatus latirostris) has become endangered partly because of a growing number of collisions with boats. A system to warn boaters of the presence of manatees, that can signal to boaters that manatees are present in the immediate vicinity, could potentially reduce these boat collisions. In order to identify the presence of manatees, acoustic methods are employed. Within this paper, three different detection algorithms are used to detect the calls of the West Indian manatee. The detection systems are tested in the laboratory using simulated manatee vocalizations from an audio compact disc. The detection method that provides the best overall performance is able to correctly identify ~=96% of the manatee vocalizations. However the system also results in a false positive rate of ~=16%. The results of this work may ultimately lead to the development of a manatee warning system that can warn boaters of the presence of manatees.

  11. Acoustic signalling reflects personality in a social mammal

    PubMed Central

    Friel, Mary; Kunc, Hansjoerg P.; Griffin, Kym; Asher, Lucy; Collins, Lisa M.

    2016-01-01

    Social interactions among individuals are often mediated through acoustic signals. If acoustic signals are consistent and related to an individual's personality, these consistent individual differences in signalling may be an important driver in social interactions. However, few studies in non-human mammals have investigated the relationship between acoustic signalling and personality. Here we show that acoustic signalling rate is repeatable and strongly related to personality in a highly social mammal, the domestic pig (Sus scrofa domestica). Furthermore, acoustic signalling varied between environments of differing quality, with males from a poor-quality environment having a reduced vocalization rate compared with females and males from an enriched environment. Such differences may be mediated by personality with pigs from a poor-quality environment having more reactive and more extreme personality scores compared with pigs from an enriched environment. Our results add to the evidence that acoustic signalling reflects personality in a non-human mammal. Signals reflecting personalities may have far reaching consequences in shaping the evolution of social behaviours as acoustic communication forms an integral part of animal societies. PMID:27429775

  12. Acoustic signalling reflects personality in a social mammal.

    PubMed

    Friel, Mary; Kunc, Hansjoerg P; Griffin, Kym; Asher, Lucy; Collins, Lisa M

    2016-06-01

    Social interactions among individuals are often mediated through acoustic signals. If acoustic signals are consistent and related to an individual's personality, these consistent individual differences in signalling may be an important driver in social interactions. However, few studies in non-human mammals have investigated the relationship between acoustic signalling and personality. Here we show that acoustic signalling rate is repeatable and strongly related to personality in a highly social mammal, the domestic pig (Sus scrofa domestica). Furthermore, acoustic signalling varied between environments of differing quality, with males from a poor-quality environment having a reduced vocalization rate compared with females and males from an enriched environment. Such differences may be mediated by personality with pigs from a poor-quality environment having more reactive and more extreme personality scores compared with pigs from an enriched environment. Our results add to the evidence that acoustic signalling reflects personality in a non-human mammal. Signals reflecting personalities may have far reaching consequences in shaping the evolution of social behaviours as acoustic communication forms an integral part of animal societies. PMID:27429775

  13. Identifying fatigue crack geometric features from acoustic emission signals

    NASA Astrophysics Data System (ADS)

    Bao, Jingjing; Poddar, Banibrata; Giurgiutiu, Victor

    2016-04-01

    Acoustic emission (AE) caused by the growth of fatigue crack were well studied by researchers. Conventional approaches predominantly are based on statistical analysis. In this study we focus on identifying geometric features of the crack from the AE signals using physics based approach. One of the main challenges of this approach is to develop a physics of materials based understanding of the generation and propagation of acoustic emissions due to the growth of a fatigue crack. As the geometry changes due to the crack growth, so does the local vibration modes around the crack. Our aim is to understand these changing local vibration modes and find possible relation between the AE signal features and the geometric features of the crack. Finite element (FE) analysis was used to model AE events due to fatigue crack growth. This was done using dipole excitation at the crack tips. Harmonic analysis was also performed on these FE models to understand the local vibration modes. Experimental study was carried out to verify these results. Piezoelectric wafer active sensors (PWAS) were used to excite cracked specimen and the local vibration modes were captured using laser Doppler vibrometry. The preliminary results show that the AE signals do carry the information related to the crack geometry.

  14. Wavelet Analysis for Acoustic Phased Array

    NASA Astrophysics Data System (ADS)

    Kozlov, Inna; Zlotnick, Zvi

    2003-03-01

    Wavelet spectrum analysis is known to be one of the most powerful tools for exploring quasistationary signals. In this paper we use wavelet technique to develop a new Direction Finding (DF) Algorithm for the Acoustic Phased Array (APA) systems. Utilising multi-scale analysis of libraries of wavelets allows us to work with frequency bands instead of individual frequency of an acoustic source. These frequency bands could be regarded as features extracted from quasistationary signals emitted by a noisy object. For detection, tracing and identification of a sound source in a noisy environment we develop smart algorithm. The essential part of this algorithm is a special interacting procedure of the above-mentioned DF-algorithm and the wavelet-based Identification (ID) algorithm developed in [4]. Significant improvement of the basic properties of a receiving APA pattern is achieved.

  15. Interpretation of acoustic signals from fluidzed beds

    SciTech Connect

    Halow, J.S.; Daw, C.S.; Finney, C.E.A.; Nguyen, K.

    1996-12-31

    Rhythmic {open_quotes}whooshing{close_quotes} sounds associated with rising bubbles are a characteristic feature of many fluidized beds. Although clearly distinguishable to the ear, these sounds are rather complicated in detail and seem to contain a large background of apparently irrelevant stochastic noise. While it is clear that these sounds contain some information about bed dynamics, it is not obvious how this information can be interpreted in a meaningful way. In this presentation we describe a technique for processing bed sounds that appears to work well for beds with large particles operating in a slugging or near-slugging mode. We find that our processing algorithm allows us to determine important bubble/slug features from sound measurements alone, including slug location at any point in time, the average bubble frequency and frequency variation, and corresponding dynamic pressure drops at different bed locations. We also have been able to correlate a portion of the acoustic signal with particle impacts on surfaces and particle motions near the grid. We conclude from our observations that relatively simple sound measurements can provide much diagnostic information and could be potentially used for bed control. 5 refs., 4 figs.

  16. Thirty years of underwater acoustic signal processing in China

    NASA Astrophysics Data System (ADS)

    Li, Qihu

    2012-11-01

    Advances in technology and theory in 30 years of underwater acoustic signal processing and its applications in China are presented in this paper. The topics include research work in the field of underwater acoustic signal modeling, acoustic field matching, ocean waveguide and internal wave, the extraction and processing technique for acoustic vector signal information, the space/time correlation characteristics of low frequency acoustic channels, the invariant features of underwater target radiated noise, the transmission technology of underwater voice/image data and its anti-interference technique. Some frontier technologies in sonar design are also discussed, including large aperture towed line array sonar, high resolution synthetic aperture sonar, deep sea siren and deep sea manned subsea vehicle, diver detection sonar and demonstration projector of national ocean monitoring system in China, etc.

  17. Assessing Linearity in the Loudness Envelope of the Messa di Voce Singing Exercise Through Acoustic Signal Analysis.

    PubMed

    Yadav, Manuj; Cabrera, Densil; Kenny, Dianna T

    2015-09-01

    Messa di voce (MDV) is a singing exercise that involves sustaining a single pitch with a linear change in loudness from silence to maximum intensity (the crescendo part) and back to silence again (the decrescendo part), with time symmetry between the two parts. Previous studies have used the sound pressure level (SPL, in decibels) of a singer's voice to measure loudness, so as to assess the linearity of each part-an approach that has limitations due to loudness and SPL not being linearly related. This article studies the loudness envelope shapes of MDVs, comparing the SPL approach with approaches that are more closely related to human loudness perception. The MDVs were performed by a cohort of tertiary singing students, recorded six times (once per semester) over a period of 3 years. The loudness envelopes were derived for a typical audience listening position, and for listening to one's own singing, using three models: SPL, Stevens' power law-based model, and a computational loudness model. The effects on the envelope shape due to room acoustics (an important effect) and vibrato (minimal effect) were also considered. The results showed that the SPL model yielded a lower proportion of linear crescendi and decrescendi, compared with other models. The Stevens' power law-based model provided results similar to the more complicated computational loudness model. Longitudinally, there was no consistent trend in the shape of the MDV loudness envelope for the cohort although there were some individual singers who exhibited improvements in linearity. PMID:25892091

  18. Modern Techniques in Acoustical Signal and Image Processing

    SciTech Connect

    Candy, J V

    2002-04-04

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

  19. Wavelet packet transform for detection of single events in acoustic emission signals

    NASA Astrophysics Data System (ADS)

    Bianchi, Davide; Mayrhofer, Erwin; Gröschl, Martin; Betz, Gerhard; Vernes, András

    2015-12-01

    Acoustic emission signals in tribology can be used for monitoring the state of bodies in contact and relative motion. The recorded signal includes information which can be associated with different events, such as the formation and propagation of cracks, appearance of scratches and so on. One of the major challenges in analyzing these acoustic emission signals is to identify parts of the signal which belong to such an event and discern it from noise. In this contribution, a wavelet packet decomposition within the framework of multiresolution analysis theory is considered to analyze acoustic emission signals to investigate the failure of tribological systems. By applying the wavelet packet transform a method for the extraction of single events in rail contact fatigue test is proposed. The extraction of such events at several stages of the test permits a classification and the analysis of the evolution of cracks in the rail.

  20. Quality Prediction of Twin Wire Arc Sprayed Coatings Using Acoustic Emission Analysis

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Abdulgader, M.; Wang, G.; Zielke, R.

    2013-03-01

    In this work, acoustic emission analysis is utilized in the twin wire arc spraying (TWAS) process to study the influence of the adjustable process parameters on the simultaneously obtained acoustic signals at the nozzle and at the substrate. The amplitude of recorded signals at the substrate was in general much higher than those recorded at the nozzle. At the substrate side, the amplitude of emitted acoustic signals is dependent on feedstock materials and is higher when using solid wires. The acoustic signals were recorded at the spraying gun for different gas pressures without arc ignition (as dry runs) in order to reveal the effect of the arc on the emitted acoustic signals. A correlation between controllable parameters, the acoustic signals, and the obtained in-flight particle characteristics was observed. This work contributes to the online control of TWAS processes and is one of many proposed publications in the research field of the conducted acoustic emission analysis.

  1. Speaker verification using combined acoustic and EM sensor signal processing

    SciTech Connect

    Ng, L C; Gable, T J; Holzrichter, J F

    2000-11-10

    Low Power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference. This greatly enhances the quality and quantity of information for many speech related applications. See Holzrichter, Burnett, Ng, and Lea, J. Acoustic. SOC. Am . 103 ( 1) 622 (1998). By combining the Glottal-EM-Sensor (GEMS) with the Acoustic-signals, we've demonstrated an almost 10 fold reduction in error rates from a speaker verification system experiment under a moderate noisy environment (-10dB).

  2. Low Bandwidth Vocoding using EM Sensor and Acoustic Signal Processing

    SciTech Connect

    Ng, L C; Holzrichter, J F; Larson, P E

    2001-10-25

    Low-power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference [1]. By combining these data with the corresponding acoustic signal, we've demonstrated an almost 10-fold bandwidth reduction in speech compression, compared to a standard 2.4 kbps LPC10 protocol used in the STU-III (Secure Terminal Unit, third generation) telephone. This paper describes a potential EM sensor/acoustic based vocoder implementation.

  3. Acoustic Aspects of Photoacoustic Signal Generation and Detection in Gases

    NASA Astrophysics Data System (ADS)

    Miklós, A.

    2015-09-01

    In this paper photoacoustic signal generation and detection in gases is investigated and discussed from the standpoint of acoustics. Four topics are considered: the effect of the absorption-desorption process of modulated and pulsed light on the heat power density released in the gas; the generation of the primary sound by the released heat in an unbounded medium; the excitation of an acoustic resonator by the primary sound; and finally, the generation of the measurable PA signal by a microphone. When light is absorbed by a molecule and the excess energy is relaxed by collisions with the surrounding molecules, the average kinetic energy, thus also the temperature of an ensemble of molecules (called "particle" in acoustics) will increase. In other words heat energy is added to the energy of the particle. The rate of the energy transfer is characterized by the heat power density. A simple two-level model of absorption-desorption is applied for describing the heat power generation process for modulated and pulsed illumination. Sound generation by a laser beam in an unbounded medium is discussed by means of the Green's function technique. It is shown that the duration of the generated sound pulse depends mostly on beam geometry. A photoacoustic signal is mostly detected in a photoacoustic cell composed of acoustic resonators, buffers, filters, etc. It is not easy to interpret the measured PA signal in such a complicated acoustic system. The acoustic response of a PA detector to different kinds of excitations (modulated cw, pulsed, periodic pulse train) is discussed. It is shown that acoustic resonators respond very differently to modulated cw excitation and to excitation by a pulse train. The microphone for detecting the PA signal is also a part of the acoustic system; its properties have to be taken into account by the design of a PA detector. The moving membrane of the microphone absorbs acoustic energy; thus, it may influence the resonance frequency and

  4. Acoustic signals of baby black caimans.

    PubMed

    Vergne, Amélie L; Aubin, Thierry; Taylor, Peter; Mathevon, Nicolas

    2011-12-01

    In spite of the importance of crocodilian vocalizations for the understanding of the evolution of sound communication in Archosauria and due to the small number of experimental investigations, information concerning the vocal world of crocodilians is limited. By studying black caimans Melanosuchus niger in their natural habitat, here we supply the experimental evidence that juvenile crocodilians can use a graded sound system in order to elicit adapted behavioral responses from their mother and siblings. By analyzing the acoustic structure of calls emitted in two different situations ('undisturbed context', during which spontaneous calls of juvenile caimans were recorded without perturbing the group, and a simulated 'predator attack', during which calls were recorded while shaking juveniles) and by testing their biological relevance through playback experiments, we reveal the existence of two functionally different types of juvenile calls that produce a different response from the mother and other siblings. Young black caimans can thus modulate the structure of their vocalizations along an acoustic continuum as a function of the emission context. Playback experiments show that both mother and juveniles discriminate between these 'distress' and 'contact' calls. Acoustic communication is thus an important component mediating relationships within family groups in caimans as it is in birds, their archosaurian relatives. Although probably limited, the vocal repertoire of young crocodilians is capable of transmitting the information necessary for allowing siblings and mother to modulate their behavior. PMID:21978842

  5. Atmospheric influence on volcano-acoustic signals

    NASA Astrophysics Data System (ADS)

    Matoza, Robin; de Groot-Hedlin, Catherine; Hedlin, Michael; Fee, David; Garcés, Milton; Le Pichon, Alexis

    2010-05-01

    Volcanoes are natural sources of infrasound, useful for studying infrasonic propagation in the atmosphere. Large, explosive volcanic eruptions typically produce signals that can be recorded at ranges of hundreds of kilometers propagating in atmospheric waveguides. In addition, sustained volcanic eruptions can produce smaller-amplitude repetitive signals recordable at >10 km range. These include repetitive impulsive signals and continuous tremor signals. The source functions of these signals can remain relatively invariant over timescales of weeks to months. Observed signal fluctuations from such persistent sources at an infrasound recording station may therefore be attributed to dynamic atmospheric propagation effects. We present examples of repetitive and sustained volcano infrasound sources at Mount St. Helens, Washington and Kilauea Volcano, Hawaii, USA. The data recorded at >10 km range show evidence of propagation effects induced by tropospheric variability at the mesoscale and microscale. Ray tracing and finite-difference simulations of the infrasound propagation produce qualitatively consistent results. However, the finite-difference simulations indicate that low-frequency effects such as diffraction, and scattering from topography may be important factors for infrasonic propagation at this scale.

  6. Study of acoustic emission signals during fracture shear deformation

    NASA Astrophysics Data System (ADS)

    Ostapchuk, A. A.; Pavlov, D. V.; Markov, V. K.; Krasheninnikov, A. V.

    2016-07-01

    We study acoustic manifestations of different regimes of shear deformation of a fracture filled with a thin layer of granular material. It is established that the observed acoustic portrait is determined by the structure of the fracture at the mesolevel. Joint analysis of the activity of acoustic pulses and their spectral characteristics makes it possible to construct the pattern of internal evolutionary processes occurring in the thin layer of the interblock contact and consider the fracture deformation process as the evolution of a self-organizing system.

  7. Surface Roughness Evaluation Based on Acoustic Emission Signals in Robot Assisted Polishing

    PubMed Central

    de Agustina, Beatriz; Marín, Marta María; Teti, Roberto; Rubio, Eva María

    2014-01-01

    The polishing process is the most common technology used in applications where a high level of surface quality is demanded. The automation of polishing processes is especially difficult due to the high level of skill and dexterity that is required. Much of this difficulty arises because of the lack of reliable data on the effect of the polishing parameters on the resulting surface roughness. An experimental study was developed to evaluate the surface roughness obtained during Robot Assisted Polishing processes by the analysis of acoustic emission signals in the frequency domain. The aim is to find out a trend of a feature or features calculated from the acoustic emission signals detected along the process. Such an evaluation was made with the objective of collecting valuable information for the establishment of the end point detection of polishing process. As a main conclusion, it can be affirmed that acoustic emission (AE) signals can be considered useful to monitor the polishing process state. PMID:25405509

  8. A unique method to study acoustic transmission through ducts using signal synthesis and averaging of acoustic pulses

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    An acoustic impulse technique using a loudspeaker driver is developed to measure the acoustic properties of a duct/nozzle system. A signal synthesis method is used to generate a desired single pulse with a flat spectrum. The convolution of the desired signal and the inverse Fourier transform of the reciprocal of the driver's response are then fed to the driver. A signal averaging process eliminates the jet mixing noise from the mixture of jet noise and the internal noise, thereby allowing very low intensity signals to be measured accurately, even for high velocity jets. A theoretical analysis is carried out to predict the incident sound field; this is used to help determine the number and locations of the induct measurement points to account for the contributions due to higher order modes present in the incident tube method. The impulse technique is validated by comparing experimentally determined acoustic characteristics of a duct-nozzle system with similar results obtained by the impedance tube method. Absolute agreement in the comparisons was poor, but the overall shapes of the time histories and spectral distributions were much alike.

  9. Modulation of Radio Frequency Signals by Nonlinearly Generated Acoustic Fields

    NASA Astrophysics Data System (ADS)

    Johnson, Spencer Joseph

    Acousto-electromagnetic scattering is a process in which an acoustic excitation is utilized to induce modulation on an electromagnetic (EM) wave. This phenomenon can be exploited in remote sensing and detection schemes whereby target objects are mechanically excited by high powered acoustic waves resulting in unique object characterizations when interrogated with EM signals. Implementation of acousto-EM sensing schemes, however, are limited by a lack of fundamental understanding of the nonlinear interaction between acoustic and EM waves and inefficient simulation methods in the determination of the radiation patterns of higher order scattered acoustic fields. To address the insufficient simulation issue, a computationally efficient mathematical model describing higher order scattered sound fields, particularly of third-order in which a 40x increase in computation speed is achieved, is derived using a multi-Gaussian beam (MGB) expansion that expresses the sound field of any arbitrary axially symmetric beam as a series of Gaussian base functions. The third-order intermodulation (IM3) frequency components are produced by considering the cascaded nonlinear second-order effects when analyzing the interaction between the first- and second-order frequency components during the nonlinear scattering of sound by sound from two noncollinear ultrasonic baffled piston sources. The theory is extended to the modeling of the sound beams generated by parametric transducer arrays, showing that the MGB model can be efficiently used to calculate both the second- and third-order sound fields of the array. Additionally, a near-to-far-field (NTFF) transformation method is developed to model the far-field characteristics of scattered sound fields, extending Kirchhoff's theorem, typically applied to EM waves, determining the far-field patterns of an acoustic source from amplitude and phase measurements made in the near-field by including the higher order sound fields generated by the

  10. Acoustic analysis of explosions in high noise environment

    NASA Astrophysics Data System (ADS)

    Man, Hong; Desai, Sachi

    2008-04-01

    Explosion detection and recognition is a critical capability to provide situational awareness to the war-fighters in battlefield. Acoustic sensors are frequently deployed to detect such events and to trigger more expensive sensing/sensor modalities (i.e. radar, laser spectroscope, IR etc.). Acoustic analysis of explosions has been intensively studied to reliably discriminate mortars, artillery, round variations, and type of blast (i.e. chemical/biological or high-explosive). One of the major challenges is high level of noise, which may include non-coherent noise generated from the environmental background and coherent noise induced by possible mobile acoustic sensor platform. In this work, we introduce a new acoustic scene analysis method to effectively enhance explosion classification reliability and reduce the false alarm rate at low SNR and with high coherent noise. The proposed method is based on acoustic signature modeling using Hidden Markov Models (HMMs). Special frequency domain acoustic features characterizing explosions as well as coherent noise are extracted from each signal segment, which forms an observation vector for HMM training and test. Classification is based on a unique model similarity measure between the HMM estimated from the test observations and the trained HMMs. Experimental tests are based on the acoustic explosion dataset from US ARMY ARDEC, and experimental results have demonstrated the effectiveness of the proposed method.

  11. Ambient noise analysis of underwater acoustic data

    NASA Astrophysics Data System (ADS)

    Snyder, Mark A.; Orlin, Pete; Schulte, Annette; Newcomb, Joal

    2003-04-01

    The Littoral Acoustic Demonstration Center (LADC) deployed three Environmental Acoustic Recording System (EARS) buoys in the northern Gulf of Mexico during the summers of 2001 and 2002. The buoys recorded frequencies up to 5859 Hz continuously for 36 days in 2001 and for 72 days in 2002. The acoustic signals recorded include sperm whale vocalizations, seismic airguns, and shipping traffic. The variability of the ambient noise is analyzed using spectrograms, time series, and statistical measurements. Variations in ambient noise before, during, and after tropical storm/hurricane passage are also investigated.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  13. A matched filter algorithm for acoustic signal detection

    NASA Astrophysics Data System (ADS)

    Jordan, D. W.

    1985-06-01

    This thesis is a presentation of several alternative acoustic filter designs which allow Space Shuttle payload experiment initiation prior to launch. This initiation is accomplished independently of any spacecraft services by means of a matched band-pass filter tuned to the acoustic signal characteristic of the Auxiliary Power Unit (APU) which is brought up to operating RPM's approximately five minutes prior to launch. These alternative designs include an analog filter built around operational amplifiers, a digital IIR design implemented with an INTEL 2920 Signal Processor, and an Adaptive FIR Weiner design. Working prototypes of the first two filters are developed and a discussion of the advantage of the 2920 digital design is presented.

  14. Infrasonic and seismic signals from earthquakes and explosions observed with Plostina seismo-acoustic array

    NASA Astrophysics Data System (ADS)

    Ghica, D.; Ionescu, C.

    2012-04-01

    Plostina seismo-acoustic array has been recently deployed by the National Institute for Earth Physics in the central part of Romania, near the Vrancea epicentral area. The array has a 2.5 km aperture and consists of 7 seismic sites (PLOR) and 7 collocated infrasound instruments (IPLOR). The array is being used to assess the importance of collocated seismic and acoustic sensors for the purposes of (1) seismic monitoring of the local and regional events, and (2) acoustic measurement, consisting of detection of the infrasound events (explosions, mine and quarry blasts, earthquakes, aircraft etc.). This paper focuses on characterization of infrasonic and seismic signals from the earthquakes and explosions (accidental and mining type). Two Vrancea earthquakes with magnitude above 5.0 were selected to this study: one occurred on 1st of May 2011 (MD = 5.3, h = 146 km), and the other one, on 4th October 2011 (MD = 5.2, h = 142 km). The infrasonic signals from the earthquakes have the appearance of the vertical component of seismic signals. Because the mechanism of the infrasonic wave formation is the coupling of seismic waves with the atmosphere, trace velocity values for such signals are compatible with the characteristics of the various seismic phases observed with PLOR array. The study evaluates and characterizes, as well, infrasound and seismic data recorded from the explosion caused by the military accident produced at Evangelos Florakis Naval Base, in Cyprus, on 11th July 2011. Additionally, seismo-acoustic signals presumed to be related to strong mine and quarry blasts were investigated. Ground truth of mine observations provides validation of this interpretation. The combined seismo-acoustic analysis uses two types of detectors for signal identification: one is the automatic detector DFX-PMCC, applied for infrasound detection and characterization, while the other one, which is used for seismic data, is based on array processing techniques (beamforming and frequency

  15. Modeling of acoustic emission signal propagation in waveguides.

    PubMed

    Zelenyak, Andreea-Manuela; Hamstad, Marvin A; Sause, Markus G R

    2015-01-01

    Acoustic emission (AE) testing is a widely used nondestructive testing (NDT) method to investigate material failure. When environmental conditions are harmful for the operation of the sensors, waveguides are typically mounted in between the inspected structure and the sensor. Such waveguides can be built from different materials or have different designs in accordance with the experimental needs. All these variations can cause changes in the acoustic emission signals in terms of modal conversion, additional attenuation or shift in frequency content. A finite element method (FEM) was used to model acoustic emission signal propagation in an aluminum plate with an attached waveguide and was validated against experimental data. The geometry of the waveguide is systematically changed by varying the radius and height to investigate the influence on the detected signals. Different waveguide materials were implemented and change of material properties as function of temperature were taken into account. Development of the option of modeling different waveguide options replaces the time consuming and expensive trial and error alternative of experiments. Thus, the aim of this research has important implications for those who use waveguides for AE testing. PMID:26007731

  16. Modeling of Acoustic Emission Signal Propagation in Waveguides

    PubMed Central

    Zelenyak, Andreea-Manuela; Hamstad, Marvin A.; Sause, Markus G. R.

    2015-01-01

    Acoustic emission (AE) testing is a widely used nondestructive testing (NDT) method to investigate material failure. When environmental conditions are harmful for the operation of the sensors, waveguides are typically mounted in between the inspected structure and the sensor. Such waveguides can be built from different materials or have different designs in accordance with the experimental needs. All these variations can cause changes in the acoustic emission signals in terms of modal conversion, additional attenuation or shift in frequency content. A finite element method (FEM) was used to model acoustic emission signal propagation in an aluminum plate with an attached waveguide and was validated against experimental data. The geometry of the waveguide is systematically changed by varying the radius and height to investigate the influence on the detected signals. Different waveguide materials were implemented and change of material properties as function of temperature were taken into account. Development of the option of modeling different waveguide options replaces the time consuming and expensive trial and error alternative of experiments. Thus, the aim of this research has important implications for those who use waveguides for AE testing. PMID:26007731

  17. Prediction of acoustic feature parameters using myoelectric signals.

    PubMed

    Lee, Ki-Seung

    2010-07-01

    It is well-known that a clear relationship exists between human voices and myoelectric signals (MESs) from the area of the speaker's mouth. In this study, we utilized this information to implement a speech synthesis scheme in which MES alone was used to predict the parameters characterizing the vocal-tract transfer function of specific speech signals. Several feature parameters derived from MES were investigated to find the optimal feature for maximization of the mutual information between the acoustic and the MES features. After the optimal feature was determined, an estimation rule for the acoustic parameters was proposed, based on a minimum mean square error (MMSE) criterion. In a preliminary study, 60 isolated words were used for both objective and subjective evaluations. The results showed that the average Euclidean distance between the original and predicted acoustic parameters was reduced by about 30% compared with the average Euclidean distance of the original parameters. The intelligibility of the synthesized speech signals using the predicted features was also evaluated. A word-level identification ratio of 65.5% and a syllable-level identification ratio of 73% were obtained through a listening test. PMID:20172775

  18. INSTRUMENTATION FOR SURVEYING ACOUSTIC SIGNALS IN NATURAL GAS TRANSMISSION LINES

    SciTech Connect

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

    2003-09-01

    In the U.S. natural gas is distributed through more than one million miles of high-pressure transmission pipelines. If all leaks and infringements could be detected quickly, it would enhance safety and U.S. energy security. Only low frequency acoustic waves appear to be detectable over distances up to 60 km where pipeline shut-off valves provide access to the inside of the pipeline. This paper describes a Portable Acoustic Monitoring Package (PAMP) developed to record and identify acoustic signals characteristic of: leaks, pump noise, valve and flow metering noise, third party infringement, manual pipeline water and gas blow-off, etc. This PAMP consists of a stainless steel 1/2 inch NPT plumbing tree rated for use on 1000 psi pipelines. Its instrumentation is designed to measure acoustic waves over the entire frequency range from zero to 16,000 Hz by means of four instruments: (1) microphone, (2) 3-inch water full range differential pressure transducer with 0.1% of range sensitivity, (3) a novel 3 inch to 100 inch water range amplifier, using an accumulator with needle valve and (4) a line-pressure transducer. The weight of the PAMP complete with all accessories is 36 pounds. This includes a remote control battery/switch box assembly on a 25-foot extension chord, a laptop data acquisition computer on a field table and a sun shield.

  19. Acoustic emission signal classification for gearbox failure detection

    NASA Astrophysics Data System (ADS)

    Shishino, Jun

    The purpose of this research is to develop a methodology and technique to determine the optimal number of clusters in acoustic emission (AE) data obtained from a ground test stand of a rotating H-60 helicopter tail gearbox by using mathematical algorithms and visual inspection. Signs of fatigue crack growth were observed from the AE signals acquired from the result of the optimal number of clusters in a data set. Previous researches have determined the number of clusters by visually inspecting the AE plots from number of iterations. This research is focused on finding the optimal number of clusters in the data set by using mathematical algorithms then using visual verification to confirm it. The AE data were acquired from the ground test stand that simulates the tail end of an H-60 Seahawk at Naval Air Station in Patuxant River, Maryland. The data acquired were filtered to eliminate durations that were greater than 100,000 is and 0 energy hit data to investigate the failure mechanisms occurring on the output bevel gear. From the filtered data, different AE signal parameters were chosen to perform iterations to see which clustering algorithms and number of outputs is the best. The clustering algorithms utilized are the Kohonen Self-organizing Map (SOM), k-mean and Gaussian Mixture Model (GMM). From the clustering iterations, the three cluster criterion algorithms were performed to observe the suggested optimal number of cluster by the criterions. The three criterion algorithms utilized are the Davies-Bouldin, Silhouette and Tou Criterions. After the criterions had suggested the optimal number of cluster for each data set, visual verification by observing the AE plots and statistical analysis of each cluster were performed. By observing the AE plots and the statistical analysis, the optimal number of cluster in the data set and effective clustering algorithms were determined. Along with the optimal number of clusters and effective clustering algorithm, the mechanisms

  20. Vibro-acoustic analysis of composite plates

    NASA Astrophysics Data System (ADS)

    Sarigül, A. S.; Karagözlü, E.

    2014-03-01

    Vibro-acoustic analysis plays a vital role on the design of aircrafts, spacecrafts, land vehicles and ships produced from thin plates backed by closed cavities, with regard to human health and living comfort. For this type of structures, it is required a coupled solution that takes into account structural-acoustic interaction which is crucial for sensitive solutions. In this study, coupled vibro-acoustic analyses of plates produced from composite materials have been performed by using finite element analysis software. The study has been carried out for E-glass/Epoxy, Kevlar/Epoxy and Carbon/Epoxy plates with different ply angles and numbers of ply. The effects of composite material, ply orientation and number of layer on coupled vibro-acoustic characteristics of plates have been analysed for various combinations. The analysis results have been statistically examined and assessed.

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

    NASA Astrophysics Data System (ADS)

    Whitlow, Travis Laron

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

  2. Low-Frequency Acoustic Signals Propagation in Buried Pipelines

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, A. L.; Lapshin, B. M.

    2016-01-01

    The article deals with the issues concerning acoustic signals propagation in the large-diameter oil pipelines caused by mechanical action on the pipe body. Various mechanisms of signals attenuation are discussed. It is shown that the calculation of the attenuation caused only by internal energy loss, i.e, the presence of viscosity, thermal conductivity and liquid pipeline wall friction lead to low results. The results of experimental studies, carried out using the existing pipeline with a diameter of 1200 mm. are shown. It is experimentally proved that the main mechanism of signal attenuation is the energy emission into the environment. The numerical values of attenuation coefficients that are 0,14- 0.18 dB/m for the pipeline of 1200 mm in diameter, in the frequency range from 50 Hz to 500 Hz, are determined.

  3. Data quality enhancement and knowledge discovery from relevant signals in acoustic emission

    NASA Astrophysics Data System (ADS)

    Mejia, Felipe; Shyu, Mei-Ling; Nanni, Antonio

    2015-10-01

    The increasing popularity of structural health monitoring has brought with it a growing need for automated data management and data analysis tools. Of great importance are filters that can systematically detect unwanted signals in acoustic emission datasets. This study presents a semi-supervised data mining scheme that detects data belonging to unfamiliar distributions. This type of outlier detection scheme is useful detecting the presence of new acoustic emission sources, given a training dataset of unwanted signals. In addition to classifying new observations (herein referred to as "outliers") within a dataset, the scheme generates a decision tree that classifies sub-clusters within the outlier context set. The obtained tree can be interpreted as a series of characterization rules for newly-observed data, and they can potentially describe the basic structure of different modes within the outlier distribution. The data mining scheme is first validated on a synthetic dataset, and an attempt is made to confirm the algorithms' ability to discriminate outlier acoustic emission sources from a controlled pencil-lead-break experiment. Finally, the scheme is applied to data from two fatigue crack-growth steel specimens, where it is shown that extracted rules can adequately describe crack-growth related acoustic emission sources while filtering out background "noise." Results show promising performance in filter generation, thereby allowing analysts to extract, characterize, and focus only on meaningful signals.

  4. Primary acoustic signal structure during free falling drop collision with a water surface

    NASA Astrophysics Data System (ADS)

    Chashechkin, Yu. D.; Prokhorov, V. E.

    2016-04-01

    Consistent optical and acoustic techniques have been used to study the structure of hydrodynamic disturbances and acoustic signals generated as a free falling drop penetrates water. The relationship between the structures of hydrodynamic and acoustic perturbations arising as a result of a falling drop contacting with the water surface and subsequent immersion into water is traced. The primary acoustic signal is characterized, in addition to stably reproduced features (steep leading edge followed by long decay with local pressure maxima), by irregular high-frequency packets, which are studied for the first time. Reproducible experimental data are used to recognize constant and variable components of the primary acoustic signal.

  5. Precursory acoustic signals and ground deformation in volcanic explosions

    NASA Astrophysics Data System (ADS)

    Bowman, D. C.; Kim, K.; Anderson, J.; Lees, J. M.; Taddeucci, J.; Graettinger, A. H.; Sonder, I.; Valentine, G.

    2013-12-01

    We investigate precursory acoustic signals that appear prior to volcanic explosions in real and experimental settings. Acoustic records of a series of experimental blasts designed to mimic maar explosions show precursory energy 0.02 to 0.05 seconds before the high amplitude overpressure arrival. These blasts consisted of 1 to 1/3 lb charges detonated in unconsolidated granular material at depths between 0.5 and 1 m, and were performed during the Buffalo Man Made Maars experiment in Springville, New York, USA. The preliminary acoustic arrival is 1 to 2 orders of magnitude lower in amplitude compared to the main blast wave. The waveforms vary from blast to blast, perhaps reflecting the different explosive yields and burial depths of each shot. Similar arrivals are present in some infrasound records at Santiaguito volcano, Guatemala, where they precede the main blast signal by about 2 seconds and are about 1 order of magnitude weaker. Precursory infrasound has also been described at Sakurajima volcano, Japan (Yokoo et al, 2013; Bull. Volc. Soc. Japan, 58, 163-181) and Suwanosejima volcano, Japan (Yokoo and Iguchi, 2010; JVGR, 196, 287-294), where it is attributed to rapid deformation of the vent region. Vent deformation has not been directly observed at these volcanoes because of the difficulty of visually observing the crater floor. However, particle image velocimetry of video records at Santiaguito has revealed rapid and widespread ground motion just prior to eruptions (Johnson et al, 2008; Nature, 456, 377-381) and may be the cause of much of the infrasound recorded at that volcano (Johnson and Lees, 2010; GRL, 37, L22305). High speed video records of the blasts during the Man Made Maars experiment also show rapid deformation of the ground immediately before the explosion plume breaches the surface. We examine the connection between source yield, burial depths, ground deformation, and the production of initial acoustic phases for each simulated maar explosion. We

  6. Computational principles underlying the recognition of acoustic signals in insects.

    PubMed

    Clemens, Jan; Hennig, R Matthias

    2013-08-01

    Many animals produce pulse-like signals during acoustic communication. These signals exhibit structure on two time scales: they consist of trains of pulses that are often broadcast in packets-so called chirps. Temporal parameters of the pulse and of the chirp are decisive for female preference. Despite these signals being produced by animals from many different taxa (e.g. frogs, grasshoppers, crickets, bushcrickets, flies), a general framework for their evaluation is still lacking. We propose such a framework, based on a simple and physiologically plausible model. The model consists of feature detectors, whose time-varying output is averaged over the signal and then linearly combined to yield the behavioral preference. We fitted this model to large data sets collected in two species of crickets and found that Gabor filters--known from visual and auditory physiology--explain the preference functions in these two species very well. We further explored the properties of Gabor filters and found a systematic relationship between parameters of the filters and the shape of preference functions. Although these Gabor filters were relatively short, they were also able to explain aspects of the preference for signal parameters on the longer time scale due to the integration step in our model. Our framework explains a wide range of phenomena associated with female preference for a widespread class of signals in an intuitive and physiologically plausible fashion. This approach thus constitutes a valuable tool to understand the functioning and evolution of communication systems in many species. PMID:23417450

  7. Signal Restoration of Non-stationary Acoustic Signals in the Time Domain

    NASA Technical Reports Server (NTRS)

    Babkin, Alexander S.

    1988-01-01

    Signal restoration is a method of transforming a nonstationary signal acquired by a ground based microphone to an equivalent stationary signal. The benefit of the signal restoration is a simplification of the flight test requirements because it could dispense with the need to acquire acoustic data with another aircraft flying in concert with the rotorcraft. The data quality is also generally improved because the contamination of the signal by the propeller and wind noise is not present. The restoration methodology can also be combined with other data acquisition methods, such as a multiple linear microphone array for further improvement of the test results. The methodology and software are presented for performing the signal restoration in the time domain. The method has no restrictions on flight path geometry or flight regimes. Only requirement is that the aircraft spatial position be known relative to the microphone location and synchronized with the acoustic data. The restoration process assumes that the moving source radiates a stationary signal, which is then transformed into a nonstationary signal by various modulation processes. The restoration contains only the modulation due to the source motion.

  8. Study on demodulated signal distribution and acoustic pressure phase sensitivity of a self-interfered distributed acoustic sensing system

    NASA Astrophysics Data System (ADS)

    Shang, Ying; Yang, Yuan-Hong; Wang, Chen; Liu, Xiao-Hui; Wang, Chang; Peng, Gang-Ding

    2016-06-01

    We propose a demodulated signal distribution theory for a self-interfered distributed acoustic sensing system. The distribution region of Rayleigh backscattering including the acoustic sensing signal in the sensing fiber is investigated theoretically under different combinations of both the path difference and pulse width Additionally we determine the optimal solution between the path difference and pulse width to obtain the maximum phase change per unit length. We experimentally test this theory and realize a good acoustic pressure phase sensitivity of  ‑150 dB re rad/(μPa·m) of fiber in the frequency range from 200 Hz to 1 kHz.

  9. Extraction of fault component from abnormal sound in diesel engines using acoustic signals

    NASA Astrophysics Data System (ADS)

    Dayong, Ning; Changle, Sun; Yongjun, Gong; Zengmeng, Zhang; Jiaoyi, Hou

    2016-06-01

    In this paper a method for extracting fault components from abnormal acoustic signals and automatically diagnosing diesel engine faults is presented. The method named dislocation superimposed method (DSM) is based on the improved random decrement technique (IRDT), differential function (DF) and correlation analysis (CA). The aim of DSM is to linearly superpose multiple segments of abnormal acoustic signals because of the waveform similarity of faulty components. The method uses sample points at the beginning of time when abnormal sound appears as the starting position for each segment. In this study, the abnormal sound belonged to shocking faulty type; thus, the starting position searching method based on gradient variance was adopted. The coefficient of similar degree between two same sized signals is presented. By comparing with a similar degree, the extracted fault component could be judged automatically. The results show that this method is capable of accurately extracting the fault component from abnormal acoustic signals induced by faulty shocking type and the extracted component can be used to identify the fault type.

  10. Floc Growth and Changes in ADV Acoustic Backscatter Signal

    NASA Astrophysics Data System (ADS)

    Rouhnia, M.; Keyvani, A.; Strom, K.

    2013-12-01

    A series of experiments were conducted to examine the effect of mud floc growth on the acoustic back-scatter signal recorded by a Nortek Vector acoustic Doppler velocimeter (ADV). Several studies have shown that calibration equations can be developed to link the backscatter strength with average suspended sediment concentration (SSC) when the sediment particle size distribution remains constant. However, when mud is present, the process of flocculation can alter the suspended particle size distribution. Past studies have shown that it is still unclear as to the degree of dependence of the calibration equation on changes in floc size. Part of the ambiguity lies in the fact that flocs can be porous and rather loosely packed and therefore might not scatter to the same extent as a grain of sand. In addition, direct, detailed measurements of floc size have not accompanied experiments examining the dependence of ADV backscatter and suspended sediment concentration. In this research, a set of laboratory experiments is used to test how floc growth affects the backscatter strength. The laboratory data is examined in light of an analytic model that was developed based on scatter theory to account for changes in both SSC and the floc properties of size and density. For the experiments, a turbulent suspension was created in a tank with a rotating paddle. Fixed concentrations of a mixture of kaolinite and montmorillonite were added to the tank in a step-wise manner. For each step, the flocs were allowed to grow to their equilibrium size before breaking the flocs with high turbulent mixing, adding more sediment, and then returning the mixing rate to a range suitable for the re-growth of flocs. During each floc growth phase, data was simultaneously collected at the same elevation in the tank using a floc camera to capture the changes in floc size, a Nortek Vector ADV for the acoustic backscatter, and a Campbell Scientific OBS 3+ for optical backscatter. Physical samples of the

  11. Estimates of the prevalence of anomalous signal losses in the Yellow Sea derived from acoustic and oceanographic computer model simulations

    NASA Astrophysics Data System (ADS)

    Chin-Bing, Stanley A.; King, David B.; Warn-Varnas, Alex C.; Lamb, Kevin G.; Hawkins, James A.; Teixeira, Marvi

    2002-05-01

    The results from collocated oceanographic and acoustic simulations in a region of the Yellow Sea near the Shandong peninsula have been presented [Chin-Bing et al., J. Acoust. Soc. Am. 108, 2577 (2000)]. In that work, the tidal flow near the peninsula was used to initialize a 2.5-dimensional ocean model [K. G. Lamb, J. Geophys. Res. 99, 843-864 (1994)] that subsequently generated internal solitary waves (solitons). The validity of these soliton simulations was established by matching satellite imagery taken over the region. Acoustic propagation simulations through this soliton field produced results similar to the anomalous signal loss measured by Zhou, Zhang, and Rogers [J. Acoust. Soc. Am. 90, 2042-2054 (1991)]. Analysis of the acoustic interactions with the solitons also confirmed the hypothesis that the loss mechanism involved acoustic mode coupling. Recently we have attempted to estimate the prevalence of these anomalous signal losses in this region. These estimates were made from simulating acoustic effects over an 80 hour space-time evolution of soliton packets. Examples will be presented that suggest the conditions necessary for anomalous signal loss may be more prevalent than previously thought. [Work supported by ONR/NRL and by a High Performance Computing DoD grant.

  12. Adaptive Plasticity in Wild Field Cricket’s Acoustic Signaling

    PubMed Central

    Bertram, Susan M.; Harrison, Sarah J.; Thomson, Ian R.; Fitzsimmons, Lauren P.

    2013-01-01

    Phenotypic plasticity can be adaptive when phenotypes are closely matched to changes in the environment. In crickets, rhythmic fluctuations in the biotic and abiotic environment regularly result in diel rhythms in density of sexually active individuals. Given that density strongly influences the intensity of sexual selection, we asked whether crickets exhibit plasticity in signaling behavior that aligns with these rhythmic fluctuations in the socio-sexual environment. We quantified the acoustic mate signaling behavior of wild-caught males of two cricket species, Gryllus veletis and G. pennsylvanicus. Crickets exhibited phenotypically plastic mate signaling behavior, with most males signaling more often and more attractively during the times of day when mating activity is highest in the wild. Most male G. pennsylvanicus chirped more often and louder, with shorter interpulse durations, pulse periods, chirp durations, and interchirp durations, and at slightly higher carrier frequencies during the time of the day that mating activity is highest in the wild. Similarly, most male G. veletis chirped more often, with more pulses per chirp, longer interpulse durations, pulse periods, and chirp durations, shorter interchirp durations, and at lower carrier frequencies during the time of peak mating activity in the wild. Among-male variation in signaling plasticity was high, with some males signaling in an apparently maladaptive manner. Body size explained some of the among-male variation in G. pennsylvanicus plasticity but not G. veletis plasticity. Overall, our findings suggest that crickets exhibit phenotypically plastic mate attraction signals that closely match the fluctuating socio-sexual context they experience. PMID:23935965

  13. Extended amplification of acoustic signals by amphibian burrows.

    PubMed

    Muñoz, Matías I; Penna, Mario

    2016-07-01

    Animals relying on acoustic signals for communication must cope with the constraints imposed by the environment for sound propagation. A resource to improve signal broadcast is the use of structures that favor the emission or the reception of sounds. We conducted playback experiments to assess the effect of the burrows occupied by the frogs Eupsophus emiliopugini and E. calcaratus on the amplitude of outgoing vocalizations. In addition, we evaluated the influence of these cavities on the reception of externally generated sounds potentially interfering with conspecific communication, namely, the vocalizations emitted by four syntopic species of anurans (E. emiliopugini, E. calcaratus, Batrachyla antartandica, and Pleurodema thaul) and the nocturnal owls Strix rufipes and Glaucidium nanum. Eupsophus advertisement calls emitted from within the burrows experienced average amplitude gains of 3-6 dB at 100 cm from the burrow openings. Likewise, the incoming vocalizations of amphibians and birds were amplified on average above 6 dB inside the cavities. The amplification of internally broadcast Eupsophus vocalizations favors signal detection by nearby conspecifics. Reciprocally, the amplification of incoming conspecific and heterospecific signals facilitates the detection of neighboring males and the monitoring of the levels of potentially interfering biotic noise by resident frogs, respectively. PMID:27209276

  14. Signal Processing, Analysis, & Display

    SciTech Connect

    Lager, Darrell; Azevado, Stephen

    1986-06-01

    SIG is a general-purpose signal processing, analysis, and display program. Its main purpose is to perform manipulations on time- and frequency-domain signals. However, it has been designed to ultimately accommodate other representations for data such as multiplexed signals and complex matrices. Two user interfaces are provided in SIG - a menu mode for the unfamiliar user and a command mode for more experienced users. In both modes errors are detected as early as possible and are indicated by friendly, meaningful messages. An on-line HELP package is also included. A variety of operations can be performed on time- and frequency-domain signals including operations on the samples of a signal, operations on the entire signal, and operations on two or more signals. Signal processing operations that can be performed are digital filtering (median, Bessel, Butterworth, and Chebychev), ensemble average, resample, auto and cross spectral density, transfer function and impulse response, trend removal, convolution, Fourier transform and inverse window functions (Hamming, Kaiser-Bessel), simulation (ramp, sine, pulsetrain, random), and read/write signals. User definable signal processing algorithms are also featured. SIG has many options including multiple commands per line, command files with arguments,commenting lines, defining commands, and automatic execution for each item in a repeat sequence. Graphical operations on signals and spectra include: x-y plots of time signals; real, imaginary, magnitude, and phase plots of spectra; scaling of spectra for continuous or discrete domain; cursor zoom; families of curves; and multiple viewports.

  15. Response of acoustic signals generated in water by energetic xenon ions

    NASA Astrophysics Data System (ADS)

    Miyachi, T.; Nakamura, Y.; Kuraza, G.; Fujii, M.; Nagashima, A.; Hasebe, N.; Kobayashi, M. N.; Kobayashi, S.; Miyajima, M.; Okudaira, O.; Yamashita, N.; Shibata, H.; Murakami, T.; Uchihori, Y.; Okada, N.; Tou, T.

    2006-05-01

    The acoustic signals generated by bombarding 400 MeV/n xenon ions in water were studied using an array of piezoelectric lead-zirconate-titanate elements. The observed signal was reduced to a bipolar form through Fourier analysis. The output voltage corresponded to the amount of energy deposit in water, and it tailed off beyond the range of 400 MeV/n xenon in water. This magnitude was explained qualitatively as cumulative processes. Its behavior was consistent with the calculations based on the Bethe-Bloch formula. Possible applications of this detector to radiology and heavily doped radiation detectors are described.

  16. Acoustic Emission Signals in Thin Plates Produced by Impact Damage

    NASA Technical Reports Server (NTRS)

    Prosser, William H.; Gorman, Michael R.; Humes, Donald H.

    1999-01-01

    Acoustic emission (AE) signals created by impact sources in thin aluminum and graphite/epoxy composite plates were analyzed. Two different impact velocity regimes were studied. Low-velocity (less than 0.21 km/s) impacts were created with an airgun firing spherical steel projectiles (4.5 mm diameter). High-velocity (1.8 to 7 km/s) impacts were generated with a two-stage light-gas gun firing small cylindrical nylon projectiles (1.5 mm diameter). Both the impact velocity and impact angle were varied. The impacts did not penetrate the aluminum plates at either low or high velocities. For high-velocity impacts in composites, there were both impacts that fully penetrated the plate as well as impacts that did not. All impacts generated very large amplitude AE signals (1-5 V at the sensor), which propagated as plate (extensional and/or flexural) modes. In the low-velocity impact studies, the signal was dominated by a large flexural mode with only a small extensional mode component detected. As the impact velocity was increased within the low velocity regime, the overall amplitudes of both the extensional and flexural modes increased. In addition, a relative increase in the amplitude of high-frequency components of the flexural mode was also observed. Signals caused by high-velocity impacts that did not penetrate the plate contained both a large extensional and flexural mode component of comparable amplitudes. The signals also contained components of much higher frequency and were easily differentiated from those caused by low-velocity impacts. An interesting phenomenon was observed in that the large flexural mode component, seen in every other case, was absent from the signal when the impact particle fully penetrated through the composite plates.

  17. Photo-acoustic analysis of dental materials and tissue

    NASA Astrophysics Data System (ADS)

    Jeleva, Pavlina Jetchkova

    2005-11-01

    The goal of the presented study is the investigation of the feasibility of using optically generated acoustic waves for analysis of dental material below laser-ablation threshold. The temperature rise of dental material and tissue has been modeled analytically and numerically, and measured experimentally. Following interactions with nano- and femto-second laser radiation the temperature rises at a rate of typically 1°C per J/cm 2, along with the generation of an acoustical wave. The results from the models agree with the experiment. The acoustic measurements show differences in the acoustic signal strength and the frequency spectrum when the canal in the porcelain phantom is empty or filled with intralipid solution. The photo-acoustic technique is found to be suitable for detection of liquids under a layer of dental porcelain material, consequently it can be the basis for building an imaging tool for dental diagnostic applications. By generating sound waves in the pulp, one would be able to evaluate it's state and the overall health of the tooth. This is of vital importance for diagnosing initial-stage inflammation.

  18. Acoustic analysis of a mechanical circulatory support.

    PubMed

    Hubbert, Laila; Sundbom, Per; Loebe, Matthias; Peterzén, Bengt; Granfeldt, Hans; Ahn, Henrik

    2014-07-01

    Mechanical circulatory support technology is continually improving. However, adverse complications do occur with devastating consequences, for example, pump thrombosis that may develop in several parts of the pump system. The aim of this study was to design an experimental clot/thrombosis model to register and analyze acoustic signals from the left ventricular assist device (LVAD) HeartMate II (HMII) (Thoratec Corporation, Inc., Pleasanton, CA, USA) and detect changes in sound signals correlating to clots in the inflow, outflow, and pump housing. Using modern telecom techniques, it was possible to register and analyze the HMII pump-specific acoustic fingerprint in an experimental model of LVAD support using a mock loop. Increase in pump speed significantly (P<0.005) changed the acoustic fingerprint at certain frequency (0-23,000 Hz) intervals (regions: R1-3 and peaks: P1,3-4). When the ball valves connected to the tubing were narrowed sequentially by ∼50% of the inner diameter (to mimic clot in the out- and inflow tubing), the frequency spectrum changed significantly (P<0.005) in P1 and P2 and R1 when the outflow tubing was narrowed. This change was not seen to the same extent when the lumen of the ball valve connected to the inflow tube was narrowed by ∼50%. More significant (P<0.005) acoustic changes were detected in P1 and P2 and R1 and R3, with the largest dB figs. in the lower frequency ranges in R1 and P2, when artificial clots and blood clots passed through the pump system. At higher frequencies, a significant change in dB figs. in R3 and P4 was detected when clots passed through the pump system. Acoustic monitoring of pump sounds may become a valuable tool in LVAD surveillance. PMID:24372095

  19. The Acoustic Structure and Information Content of Female Koala Vocal Signals

    PubMed Central

    Charlton, Benjamin D.

    2015-01-01

    Determining the information content of animal vocalisations can give valuable insights into the potential functions of vocal signals. The source-filter theory of vocal production allows researchers to examine the information content of mammal vocalisations by linking variation in acoustic features with variation in relevant physical characteristics of the caller. Here I used a source-filter theory approach to classify female koala vocalisations into different call-types, and determine which acoustic features have the potential to convey important information about the caller to other conspecifics. A two-step cluster analysis classified female calls into bellows, snarls and tonal rejection calls. Additional results revealed that female koala vocalisations differed in their potential to provide information about a given caller’s phenotype that may be of importance to receivers. Female snarls did not contain reliable acoustic cues to the caller’s identity and age. In contrast, female bellows and tonal rejection calls were individually distinctive, and the tonal rejection calls of older female koalas had consistently lower mean, minimum and maximum fundamental frequency. In addition, female bellows were significantly shorter in duration and had higher fundamental frequency, formant frequencies, and formant frequency spacing than male bellows. These results indicate that female koala vocalisations have the potential to signal the caller’s identity, age and sex. I go on to discuss the anatomical basis for these findings, and consider the possible functional relevance of signalling this type of information in the koala’s natural habitat. PMID:26465340

  20. The Acoustic Structure and Information Content of Female Koala Vocal Signals.

    PubMed

    Charlton, Benjamin D

    2015-01-01

    Determining the information content of animal vocalisations can give valuable insights into the potential functions of vocal signals. The source-filter theory of vocal production allows researchers to examine the information content of mammal vocalisations by linking variation in acoustic features with variation in relevant physical characteristics of the caller. Here I used a source-filter theory approach to classify female koala vocalisations into different call-types, and determine which acoustic features have the potential to convey important information about the caller to other conspecifics. A two-step cluster analysis classified female calls into bellows, snarls and tonal rejection calls. Additional results revealed that female koala vocalisations differed in their potential to provide information about a given caller's phenotype that may be of importance to receivers. Female snarls did not contain reliable acoustic cues to the caller's identity and age. In contrast, female bellows and tonal rejection calls were individually distinctive, and the tonal rejection calls of older female koalas had consistently lower mean, minimum and maximum fundamental frequency. In addition, female bellows were significantly shorter in duration and had higher fundamental frequency, formant frequencies, and formant frequency spacing than male bellows. These results indicate that female koala vocalisations have the potential to signal the caller's identity, age and sex. I go on to discuss the anatomical basis for these findings, and consider the possible functional relevance of signalling this type of information in the koala's natural habitat. PMID:26465340

  1. Moisture estimation in power transformer oil using acoustic signals and spectral kurtosis

    NASA Astrophysics Data System (ADS)

    Leite, Valéria C. M. N.; Veloso, Giscard F. C.; Borges da Silva, Luiz Eduardo; Lambert-Torres, Germano; Borges da Silva, Jonas G.; Onofre Pereira Pinto, João

    2016-03-01

    The aim of this paper is to present a new technique for estimating the contamination by moisture in power transformer insulating oil based on the spectral kurtosis analysis of the acoustic signals of partial discharges (PDs). Basically, in this approach, the spectral kurtosis of the PD acoustic signal is calculated and the correlation between its maximum value and the moisture percentage is explored to find a function that calculates the moisture percentage. The function can be easily implemented in DSP, FPGA, or any other type of embedded system for online moisture monitoring. To evaluate the proposed approach, an experiment is assembled with a piezoelectric sensor attached to a tank, which is filled with insulating oil samples contaminated by different levels of moisture. A device generating electrical discharges is submerged into the oil to simulate the occurrence of PDs. Detected acoustic signals are processed using fast kurtogram algorithm to extract spectral kurtosis values. The obtained data are used to find the fitting function that relates the water contamination to the maximum value of the spectral kurtosis. Experimental results show that the proposed method is suitable for online monitoring system of power transformers.

  2. Wavelet Transform Of Acoustic Signal From A Ranque- Hilsch Vortex Tube

    NASA Astrophysics Data System (ADS)

    Istihat, Y.; Wisnoe, W.

    2015-09-01

    This paper presents the frequency analysis of flow in a Ranque-Hilsch Vortex Tube (RHVT) obtained from acoustic signal using microphones in an isolated formation setup. Data Acquisition System (DAS) that incorporates Analog to Digital Converter (ADC) with laptop computer has been used to acquire the wave data. Different inlet pressures (20, 30, 40, 50 and 60 psi) are supplied and temperature differences are recorded. Frequencies produced from a RHVT are experimentally measured and analyzed by means of Wavelet Transform (WT). Morlet Wavelet is used and relation between Pressure variation, Temperature and Frequency are studied. Acoustic data has been analyzed using Matlab® and time-frequency analysis (Scalogram) is presented. Results show that the Pressure is proportional with the Frequency inside the RHVT whereby two distinct working frequencies is pronounced in between 4-8 kHz.

  3. Acoustic Analysis of the Tremulous Voice: Assessing the Utility of the Correlation Dimension and Perturbation Parameters

    ERIC Educational Resources Information Center

    Shao, Jun; MacCallum, Julia K.; Zhang, Yu; Sprecher, Alicia; Jiang, Jack J.

    2010-01-01

    Acoustic analysis may provide a useful means to quantitatively characterize the tremulous voice. Signals were obtained from 25 subjects with diagnoses of either Parkinson's disease or vocal polyps exhibiting vocal tremor. These were compared to signals from 24 subjects with normal voices. Signals were analyzed via correlation dimension and several…

  4. Seismo-acoustic Signals Recorded at KSIAR, the Infrasound Array Installed at PS31

    NASA Astrophysics Data System (ADS)

    Kim, T. S.; Che, I. Y.; Jeon, J. S.; Chi, H. C.; Kang, I. B.

    2014-12-01

    One of International Monitoring System (IMS)'s primary seismic stations, PS31, called Korea Seismic Research Station (KSRS), was installed around Wonju, Korea in 1970s. It has been operated by US Air Force Technical Applications Center (AFTAC) for more than 40 years. KSRS is composed of 26 seismic sensors including 19 short period, 6 long period and 1 broad band seismometers. The 19 short period sensors were used to build an array with a 10-km aperture while the 6 long period sensors were used for a relatively long period array with a 40-km aperture. After KSRS was certified as an IMS station in 2006 by Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), Korea Institute of Geoscience and Mineral Resources (KIGAM) which is the Korea National Data Center started to take over responsibilities on the operation and maintenance of KSRS from AFTAC. In April of 2014, KIGAM installed an infrasound array, KSIAR, on the existing four short period seismic stations of KSRS, the sites KS05, KS06, KS07 and KS16. The collocated KSIAR changed KSRS from a seismic array into a seismo-acoustic array. The aperture of KSIAR is 3.3 km. KSIAR also has a 100-m small aperture infrasound array at KS07. The infrasound data from KSIAR except that from the site KS06 is being transmitted in real time to KIGAM with VPN and internet line. An initial analysis on seismo-acoustic signals originated from local and regional distance ranges has been performed since May 2014. The analysis with the utilization of an array process called Progressive Multi-Channel Correlation (PMCC) detected seismo-acoustic signals caused by various sources including small explosions in relation to constructing local tunnels and roads. Some of them were not found in the list of automatic bulletin of KIGAM. The seismo-acoustic signals recorded by KSIAR are supplying a useful information for discriminating local and regional man-made events from natural events.

  5. Acoustic effects of the ATOC signal (75 Hz, 195 dB) on dolphins and whales

    SciTech Connect

    Au, W.W.; Nachtigall, P.E.; Pawloski, J.L.

    1997-05-01

    The Acoustic Thermometry of Ocean Climate (ATOC) program of Scripps Institution of Oceanography and the Applied Physics Laboratory, University of Washington, will broadcast a low-frequency 75-Hz phase modulated acoustic signal over ocean basins in order to study ocean temperatures on a global scale and examine the effects of global warming. One of the major concerns is the possible effect of the ATOC signal on marine life, especially on dolphins and whales. In order to address this issue, the hearing sensitivity of a false killer whale ({ital Pseudorca crassidens}) and a Risso{close_quote}s dolphin ({ital Grampus griseus}) to the ATOC sound was measured behaviorally. A staircase procedure with the signal levels being changed in 1-dB steps was used to measure the animals{close_quote} threshold to the actual ATOC coded signal. The results indicate that small odontocetes such as the {ital Pseudorca} and {ital Grampus} swimming directly above the ATOC source will not hear the signal unless they dive to a depth of approximately 400 m. A sound propagation analysis suggests that the sound-pressure level at ranges greater than 0.5 km will be less than 130 dB for depths down to about 500 m. Several species of baleen whales produce sounds much greater than 170{endash}180 dB. With the ATOC source on the axis of the deep sound channel (greater than 800 m), the ATOC signal will probably have minimal physical and physiological effects on cetaceans. {copyright} {ital 1997 Acoustical Society of America.}

  6. Signal Processing, Analysis, & Display

    1986-06-01

    SIG is a general-purpose signal processing, analysis, and display program. Its main purpose is to perform manipulations on time- and frequency-domain signals. However, it has been designed to ultimately accommodate other representations for data such as multiplexed signals and complex matrices. Two user interfaces are provided in SIG - a menu mode for the unfamiliar user and a command mode for more experienced users. In both modes errors are detected as early as possible andmore » are indicated by friendly, meaningful messages. An on-line HELP package is also included. A variety of operations can be performed on time- and frequency-domain signals including operations on the samples of a signal, operations on the entire signal, and operations on two or more signals. Signal processing operations that can be performed are digital filtering (median, Bessel, Butterworth, and Chebychev), ensemble average, resample, auto and cross spectral density, transfer function and impulse response, trend removal, convolution, Fourier transform and inverse window functions (Hamming, Kaiser-Bessel), simulation (ramp, sine, pulsetrain, random), and read/write signals. User definable signal processing algorithms are also featured. SIG has many options including multiple commands per line, command files with arguments,commenting lines, defining commands, and automatic execution for each item in a repeat sequence. Graphical operations on signals and spectra include: x-y plots of time signals; real, imaginary, magnitude, and phase plots of spectra; scaling of spectra for continuous or discrete domain; cursor zoom; families of curves; and multiple viewports.« less

  7. Filterbank-based independent component analysis for acoustic mixtures

    NASA Astrophysics Data System (ADS)

    Park, Hyung-Min

    2011-06-01

    Independent component analysis (ICA) for acoustic mixtures has been a challenging problem due to very complex reverberation involved in real-world mixing environments. In an effort to overcome disadvantages of the conventional time domain and frequency domain approaches, this paper describes filterbank-based independent component analysis for acoustic mixtures. In this approach, input signals are split into subband signals and decimated. A simplified network performs ICA on the decimated signals, and finally independent components are synthesized. First, a uniform filterbank is employed in the approach for basic and simple derivation and implementation. The uniform-filterbank-based approach achieves better separation performance than the frequency domain approach and gives faster convergence speed with less computational complexity than the time domain approach. Since most of natural signals have exponentially or more steeply decreasing energy as the frequency increases, the spectral characteristics of natural signals introduce a Bark-scale filterbank which divides low frequency region minutely and high frequency region widely. The Bark-scale-filterbank-based approach shows faster convergence speed than the uniform-filterbank-based one because it has more whitened inputs in low frequency subbands. It also improves separation performance as it has enough data to train adaptive parameters exactly in high frequency subbands.

  8. Ocean acoustic signal processing: A model-based approach

    SciTech Connect

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

    1992-12-01

    A model-based approach is proposed to solve the ocean acoustic signal processing problem that is based on a state-space representation of the normal-mode propagation model. It is shown that this representation can be utilized to spatially propagate both modal (depth) and range functions given the basic parameters (wave numbers, etc.) developed from the solution of the associated boundary value problem. This model is then generalized to the stochastic case where an approximate Gauss--Markov model evolves. The Gauss--Markov representation, in principle, allows the inclusion of stochastic phenomena such as noise and modeling errors in a consistent manner. Based on this framework, investigations are made of model-based solutions to the signal enhancement, detection and related parameter estimation problems. In particular, a modal/pressure field processor is designed that allows {ital in} {ital situ} recursive estimation of the sound velocity profile. Finally, it is shown that the associated residual or so-called innovation sequence that ensues from the recursive nature of this formulation can be employed to monitor the model's fit to the data and also form the basis of a sequential detector.

  9. Acoustic emission source localization based on distance domain signal representation

    NASA Astrophysics Data System (ADS)

    Gawronski, M.; Grabowski, K.; Russek, P.; Staszewski, W. J.; Uhl, T.; Packo, P.

    2016-04-01

    Acoustic emission is a vital non-destructive testing technique and is widely used in industry for damage detection, localisation and characterization. The latter two aspects are particularly challenging, as AE data are typically noisy. What is more, elastic waves generated by an AE event, propagate through a structural path and are significantly distorted. This effect is particularly prominent for thin elastic plates. In these media the dispersion phenomenon results in severe localisation and characterization issues. Traditional Time Difference of Arrival methods for localisation techniques typically fail when signals are highly dispersive. Hence, algorithms capable of dispersion compensation are sought. This paper presents a method based on the Time - Distance Domain Transform for an accurate AE event localisation. The source localisation is found through a minimization problem. The proposed technique focuses on transforming the time signal to the distance domain response, which would be recorded at the source. Only, basic elastic material properties and plate thickness are used in the approach, avoiding arbitrary parameters tuning.

  10. Vibro-acoustic analysis of the acoustic-structure interaction of flexible structure due to acoustic excitation

    NASA Astrophysics Data System (ADS)

    Djojodihardjo, Harijono

    2015-03-01

    The application of BE-FE acoustic-structure interaction on a structure subject to acoustic load is elaborated using the boundary element-finite element acoustic structural coupling and the utilization of the computational scheme developed earlier. The plausibility of the numerical treatment is investigated and validated through application to generic cases. The analysis carried out in the work is intended to serve as a baseline in the analysis of acoustic structure interaction for lightweight structures. Results obtained thus far exhibit the robustness of the method developed.

  11. Signal processing for passive detection and classification of underwater acoustic signals

    NASA Astrophysics Data System (ADS)

    Chung, Kil Woo

    2011-12-01

    This dissertation examines signal processing for passive detection, classification and tracking of underwater acoustic signals for improving port security and the security of coastal and offshore operations. First, we consider the problem of passive acoustic detection of a diver in a shallow water environment. A frequency-domain multi-band matched-filter approach to swimmer detection is presented. The idea is to break the frequency contents of the hydrophone signals into multiple narrow frequency bands, followed by time averaged (about half of a second) energy calculation over each band. Then, spectra composed of such energy samples over the chosen frequency bands are correlated to form a decision variable. The frequency bands with highest Signal/Noise ratio are used for detection. The performance of the proposed approach is demonstrated for experimental data collected for a diver in the Hudson River. We also propose a new referenceless frequency-domain multi-band detector which, unlike other reference-based detectors, does not require a diver specific signature. Instead, our detector matches to a general feature of the diver spectrum in the high frequency range: the spectrum is roughly periodic in time and approximately flat when the diver exhales. The performance of the proposed approach is demonstrated by using experimental data collected from the Hudson River. Moreover, we present detection, classification and tracking of small vessel signals. Hydroacoustic sensors can be applied for the detection of noise generated by vessels, and this noise can be used for vessel detection, classification and tracking. This dissertation presents recent improvements aimed at the measurement and separation of ship DEMON (Detection of Envelope Modulation on Noise) acoustic signatures in busy harbor conditions. Ship signature measurements were conducted in the Hudson River and NY Harbor. The DEMON spectra demonstrated much better temporal stability compared with the full ship

  12. A Fibre Bragg Grating Sensor as a Receiver for Acoustic Communications Signals

    PubMed Central

    Wild, Graham; Hinckley, Steven

    2011-01-01

    A Fibre Bragg Grating (FBG) acoustic sensor is used as a receiver for acoustic communications signals. Acoustic transmissions were generated in aluminium and Carbon Fibre Composite (CFC) panels. The FBG receiver was coupled to the bottom surface opposite a piezoelectric transmitter. For the CFC, a second FBG was embedded within the layup for comparison. We show the transfer function, frequency response, and transient response of the acoustic communications channels. In addition, the FBG receiver was used to detect Phase Shift Keying (PSK) communications signals, which was shown to be the most robust method in a highly resonant communications channel. PMID:22346585

  13. Neural network data analysis for laser-induced thermal acoustics

    NASA Astrophysics Data System (ADS)

    Schlamp, Stefan; Hornung, Hans G.; Cummings, Eric B.

    2000-06-01

    A general, analytical closed-form solution for laser-induced thermal acoustic (LITA) signals using homodyne or heterodyne detection and using electrostrictive and thermal gratings is derived. A one-hidden-layer feed-forward neural network is trained using back-propagation learning and a steepest descent learning rule to extract the speed of sound and flow velocity from a heterodyne LITA signal. The effect of the network size on the performance is demonstrated. The accuracy is determined with a second set of LITA signals that were not used during the training phase. The accuracy is found to be better than that of a conventional frequency decomposition technique while being computationally as efficient. This data analysis method is robust with respect to noise, numerically stable and fast enough for real-time data analysis.

  14. Filtering of Acoustic Signals within the Hearing Organ

    PubMed Central

    Ramamoorthy, Sripriya; Chen, Fangyi; Jacques, Steven L.; Wang, Ruikang; Choudhury, Niloy; Fridberger, Anders

    2014-01-01

    The detection of sound by the mammalian hearing organ involves a complex mechanical interplay among different cell types. The inner hair cells, which are the primary sensory receptors, are stimulated by the structural vibrations of the entire organ of Corti. The outer hair cells are thought to modulate these sound-evoked vibrations to enhance hearing sensitivity and frequency resolution, but it remains unclear whether other structures also contribute to frequency tuning. In the current study, sound-evoked vibrations were measured at the stereociliary side of inner and outer hair cells and their surrounding supporting cells, using optical coherence tomography interferometry in living anesthetized guinea pigs. Our measurements demonstrate the presence of multiple vibration modes as well as significant differences in frequency tuning and response phase among different cell types. In particular, the frequency tuning at the inner hair cells differs from other cell types, causing the locus of maximum inner hair cell activation to be shifted toward the apex of the cochlea compared with the outer hair cells. These observations show that additional processing and filtering of acoustic signals occur within the organ of Corti before inner hair cell excitation, representing a departure from established theories. PMID:24990925

  15. MASS-DEPENDENT BARYON ACOUSTIC OSCILLATION SIGNAL AND HALO BIAS

    SciTech Connect

    Wang Qiao; Zhan Hu

    2013-05-10

    We characterize the baryon acoustic oscillations (BAO) feature in halo two-point statistics using N-body simulations. We find that nonlinear damping of the BAO signal is less severe for halos in the mass range we investigate than for dark matter. The amount of damping depends weakly on the halo mass. The correlation functions show a mass-dependent drop of the halo clustering bias below roughly 90 h {sup -1} Mpc, which coincides with the scale of the BAO trough. The drop of bias is 4% for halos with mass M > 10{sup 14} h {sup -1} M{sub Sun} and reduces to roughly 2% for halos with mass M > 10{sup 13} h {sup -1} M{sub Sun }. In contrast, halo biases in simulations without BAO change more smoothly around 90 h {sup -1} Mpc. In Fourier space, the bias of M > 10{sup 14} h {sup -1} M{sub Sun} halos decreases smoothly by 11% from wavenumber k = 0.012 h Mpc{sup -1} to 0.2 h Mpc{sup -1}, whereas that of M > 10{sup 13} h {sup -1} M{sub Sun} halos decreases by less than 4% over the same range. By comparing the halo biases in pairs of otherwise identical simulations, one with and the other without BAO, we also observe a modulation of the halo bias. These results suggest that precise calibrations of the mass-dependent BAO signal and scale-dependent bias on large scales would be needed for interpreting precise measurements of the two-point statistics of clusters or massive galaxies in the future.

  16. Acoustic Emission Analysis Applet (AEAA) Software

    NASA Technical Reports Server (NTRS)

    Nichols, Charles T.; Roth, Don J.

    2013-01-01

    NASA Glenn Research and NASA White Sands Test Facility have developed software supporting an automated pressure vessel structural health monitoring (SHM) system based on acoustic emissions (AE). The software, referred to as the Acoustic Emission Analysis Applet (AEAA), provides analysts with a tool that can interrogate data collected on Digital Wave Corp. and Physical Acoustics Corp. software using a wide spectrum of powerful filters and charts. This software can be made to work with any data once the data format is known. The applet will compute basic AE statistics, and statistics as a function of time and pressure (see figure). AEAA provides value added beyond the analysis provided by the respective vendors' analysis software. The software can handle data sets of unlimited size. A wide variety of government and commercial applications could benefit from this technology, notably requalification and usage tests for compressed gas and hydrogen-fueled vehicles. Future enhancements will add features similar to a "check engine" light on a vehicle. Once installed, the system will ultimately be used to alert International Space Station crewmembers to critical structural instabilities, but will have little impact to missions otherwise. Diagnostic information could then be transmitted to experienced technicians on the ground in a timely manner to determine whether pressure vessels have been impacted, are structurally unsound, or can be safely used to complete the mission.

  17. The effect of artificial rain on backscattered acoustic signal: first measurements

    NASA Astrophysics Data System (ADS)

    Titchenko, Yuriy; Karaev, Vladimir; Meshkov, Evgeny; Goldblat, Vladimir

    . The estimates of roughness parameters variability during precipitation are obtained. The first measurements of rain influencing on cross section and Doppler spectrum of backscattered acoustic signal was carried out. The obtained results were compared with calculations based on the theoretical model. Acknowledgments. The reported study was supported by RFBR, research project No. 14-05-31517 mol_a. References 1. Bliven Larry, Branger Hubert, Sobieski Piotr, Giovanangeli Jean-Paul, An analysis of scatterometer returns from a water surface agitated by artificial rain : evidence that ring-waves are the mean feature, Intl. Jl. of Remote Sensing, Vol. 14, n 12, 1993, pp. 2315-2329, 1993 2. Sobieski Piotr, Craeye Christophe, Bliven Larry, A Relationship Between Rain Radar Reflectivity and Height Elevation Variance of Ringwaves due to the Impact of Rain on the Sea Surface, Radio Science, AGU, 44, RS3005, 1-20, 2009 3. Weissman, D. E., and M. A. Bourassa, Measurements of the Effect of Rain-induced Sea Surface Roughness on the Satellite Scatterometer Radar Cross Section, IEEE Trans. Geosci. Remote Sens., 46, 2882-2894, 2008 4. B. Brumley, La Jolla, E.Terray, B.String, «System and method for measuring wave directional spectrum and wave height», USA Patent N US 2004/0184350 A1,23 September 2004 5. James H. Churchill, Albert J. Plueddemann, Stephen M. Faluotico, «Extracting Wind Sea and Swell from Directional Wave Spectra derived from a bottom-mounted ADCP», Woods Hole Oceanographic Institution, Technical Report WHOI-2006-13 6. V. Yu. Karaev, M. B. Kanevsky, E. M. Meshkov, Measuring the parameters of sea-surface roughness by underwater acoustic systems: discussion of the device concept, Radiophysics and Quantum Electronics, V. 53, I. 9-10. pp. 569-579, 2011

  18. Acoustic Facies Analysis of Side-Scan Sonar Data

    NASA Astrophysics Data System (ADS)

    Dwan, Fa Shu

    Acoustic facies analysis methods have allowed the generation of system-independent values for the quantitative seafloor acoustic parameter, backscattering strength, from GLORIA and (TAMU) ^2 side-scan sonar data. The resulting acoustic facies parameters enable quantitative comparisons of data collected by different sonar systems, data from different environments, and measurements made with survey geometries. Backscattering strength values were extracted from the sonar amplitude data by inversion based on the sonar equation. Image processing products reveal seafloor features and patterns of relative intensity. To quantitatively compare data collected at different times or by different systems, and to ground truth-measurements and geoacoustic models, quantitative corrections must be made on any given data set for system source level, beam pattern, time-varying gain, processing gain, transmission loss, absorption, insonified area contribution, and grazing angle effects. In the sonar equation, backscattering strength is the sonar parameter which is directly related to seafloor properties. The GLORIA data used in this study are from the edge of a distal lobe of the Monterey Fan. An interfingered region of strong and weak seafloor signal returns from a flat seafloor region provides an ideal data set for this study. Inversion of imagery data from the region allows the quantitative definition of different acoustic facies. The (TAMU) ^2 data used are from a calibration site near the Green Canyon area of the Gulf of Mexico. Acoustic facies analysis techniques were implemented to generate statistical information for acoustic facies based on the estimates of backscattering strength. The backscattering strength values have been compared with Lambert's Law and other functions to parameterize the description of the acoustic facies. The resulting Lambertian constant values range from -26 dB to -36 dB. A modified Lambert relationship, which consists of both intercept and slope

  19. Phylogenetic signal in the acoustic parameters of the advertisement calls of four clades of anurans

    PubMed Central

    2013-01-01

    Background Anuran vocalizations, especially their advertisement calls, are largely species-specific and can be used to identify taxonomic affiliations. Because anurans are not vocal learners, their vocalizations are generally assumed to have a strong genetic component. This suggests that the degree of similarity between advertisement calls may be related to large-scale phylogenetic relationships. To test this hypothesis, advertisement calls from 90 species belonging to four large clades (Bufo, Hylinae, Leptodactylus, and Rana) were analyzed. Phylogenetic distances were estimated based on the DNA sequences of the 12S mitochondrial ribosomal RNA gene, and, for a subset of 49 species, on the rhodopsin gene. Mean values for five acoustic parameters (coefficient of variation of root-mean-square amplitude, dominant frequency, spectral flux, spectral irregularity, and spectral flatness) were computed for each species. We then tested for phylogenetic signal on the body-size-corrected residuals of these five parameters, using three statistical tests (Moran’s I, Mantel, and Blomberg’s K) and three models of genetic distance (pairwise distances, Abouheif’s proximities, and the variance-covariance matrix derived from the phylogenetic tree). Results A significant phylogenetic signal was detected for most acoustic parameters on the 12S dataset, across statistical tests and genetic distance models, both for the entire sample of 90 species and within clades in several cases. A further analysis on a subset of 49 species using genetic distances derived from rhodopsin and from 12S broadly confirmed the results obtained on the larger sample, indicating that the phylogenetic signals observed in these acoustic parameters can be detected using a variety of genetic distance models derived either from a variable mitochondrial sequence or from a conserved nuclear gene. Conclusions We found a robust relationship, in a large number of species, between anuran phylogenetic relatedness and

  20. Standardization of pitch range settings in voice acoustic analysis

    PubMed Central

    Vogel, Adam P.; Maruff, Paul; Snyder, Peter J.; Mundt, James C.

    2009-01-01

    Voice acoustic analysis is typically a labor intensive, time consuming process that requires the application of idiosyncratic parameters tailored to individual aspects of the speech signal. These processes limit the efficiency and utility of voice analysis in clinical practice as well as applied research and development. In the current study, we analyzed 1120 voice files using standard techniques (case by case hand analysis); taking roughly 8 weeks of personnel time complete. The obtained results were then compared to the analytic output of several automated analysis scripts that made use of pre-set pitch range parameters. The automated analysis scripts reduced processing time of the 1680 speech samples to less than 2.5 hours and produced results comparable to the hand analysis when pitch window were appropriately selected to account for known population differences (i.e., sex differences). Caution should be exercised when applying suggested settings to pathological voice populations. PMID:19363172

  1. Signature analysis of acoustic emission from graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Russell, S. S.; Henneke, E. G., II

    1977-01-01

    Acoustic emissions were monitored for crack extension across and parallel to the fibers in a single ply and multiply laminates of graphite epoxy composites. Spectrum analysis was performed on the transient signal to ascertain if the fracture mode can be characterized by a particular spectral pattern. The specimens were loaded to failure quasistatically in a tensile machine. Visual observations were made via either an optical microscope or a television camera. The results indicate that several types of characteristics in the time and frequency domain correspond to different types of failure.

  2. Airborne chemistry: acoustic levitation in chemical analysis.

    PubMed

    Santesson, Sabina; Nilsson, Staffan

    2004-04-01

    This review with 60 references describes a unique path to miniaturisation, that is, the use of acoustic levitation in analytical and bioanalytical chemistry applications. Levitation of small volumes of sample by means of a levitation technique can be used as a way to avoid solid walls around the sample, thus circumventing the main problem of miniaturisation, the unfavourable surface-to-volume ratio. Different techniques for sample levitation have been developed and improved. Of the levitation techniques described, acoustic or ultrasonic levitation fulfils all requirements for analytical chemistry applications. This technique has previously been used to study properties of molten materials and the equilibrium shape()and stability of liquid drops. Temperature and mass transfer in levitated drops have also been described, as have crystallisation and microgravity applications. The airborne analytical system described here is equipped with different and exchangeable remote detection systems. The levitated drops are normally in the 100 nL-2 microL volume range and additions to the levitated drop can be made in the pL-volume range. The use of levitated drops in analytical and bioanalytical chemistry offers several benefits. Several remote detection systems are compatible with acoustic levitation, including fluorescence imaging detection, right angle light scattering, Raman spectroscopy, and X-ray diffraction. Applications include liquid/liquid extractions, solvent exchange, analyte enrichment, single-cell analysis, cell-cell communication studies, precipitation screening of proteins to establish nucleation conditions, and crystallisation of proteins and pharmaceuticals. PMID:14762640

  3. Estimation of the Tool Condition by Applying the Wavelet Transform to Acoustic Emission Signals

    SciTech Connect

    Gomez, M. P.; Piotrkowski, R.; Ruzzante, J. E.; D'Attellis, C. E.

    2007-03-21

    This work follows the search of parameters to evaluate the tool condition in machining processes. The selected sensing technique is acoustic emission and it is applied to a turning process of steel samples. The obtained signals are studied using the wavelet transformation. The tool wear level is quantified as a percentage of the final wear specified by the Standard ISO 3685. The amplitude and relevant scale obtained of acoustic emission signals could be related with the wear level.

  4. Investigation of Interference Phenomena of Broadband Acoustic Vector Signals in Shallow Water

    NASA Astrophysics Data System (ADS)

    Piao, Shengchun; Ren, Qunyan

    2010-09-01

    Although the ocean environment in shallow water is very complex, there still exists stable interference pattern for broadband low frequency sound propagation. The waveguide invariant concept is introduced to describe the broadband interference structure of the acoustic pressure field in a waveguide and now it is widely used in underwater acoustic signal processing. Acoustic vector sensor can measure the particle velocity in the ocean and provides more information for the underwater sound field. In this paper, the interference phenomena of broadband vector acoustic signals in shallow water are investigated by numerical simulation. Energy spatial-frequency distributions are shown for energy flux density vector obtained by combination of pressure and particle velocity signals and they are analyzed according to normal mode theory. Comparisons of the interference structure between the scale acoustic field and vector acoustic field also have been made. The waveguide invariant concept is extended to describe the interference structure of vector acoustic field in shallow water. A method for extraction of the waveguide invariant from interference patterns in vector acoustic field spectrograms is presented, which can be used in matched-field processing and geoacoustic inversion. It is shown that this method may have more advantages than the traditional methods which calculate the waveguide invariant using measured sound pressure in the ocean.

  5. Graph-based sensor fusion for classification of transient acoustic signals.

    PubMed

    Srinivas, Umamahesh; Nasrabadi, Nasser M; Monga, Vishal

    2015-03-01

    Advances in acoustic sensing have enabled the simultaneous acquisition of multiple measurements of the same physical event via co-located acoustic sensors. We exploit the inherent correlation among such multiple measurements for acoustic signal classification, to identify the launch/impact of munition (i.e., rockets, mortars). Specifically, we propose a probabilistic graphical model framework that can explicitly learn the class conditional correlations between the cepstral features extracted from these different measurements. Additionally, we employ symbolic dynamic filtering-based features, which offer improvements over the traditional cepstral features in terms of robustness to signal distortions. Experiments on real acoustic data sets show that our proposed algorithm outperforms conventional classifiers as well as the recently proposed joint sparsity models for multisensor acoustic classification. Additionally our proposed algorithm is less sensitive to insufficiency in training samples compared to competing approaches. PMID:25014986

  6. Spectral analysis methods for vehicle interior vibro-acoustics identification

    NASA Astrophysics Data System (ADS)

    Hosseini Fouladi, Mohammad; Nor, Mohd. Jailani Mohd.; Ariffin, Ahmad Kamal

    2009-02-01

    Noise has various effects on comfort, performance and health of human. Sound are analysed by human brain based on the frequencies and amplitudes. In a dynamic system, transmission of sound and vibrations depend on frequency and direction of the input motion and characteristics of the output. It is imperative that automotive manufacturers invest a lot of effort and money to improve and enhance the vibro-acoustics performance of their products. The enhancement effort may be very difficult and time-consuming if one relies only on 'trial and error' method without prior knowledge about the sources itself. Complex noise inside a vehicle cabin originated from various sources and travel through many pathways. First stage of sound quality refinement is to find the source. It is vital for automotive engineers to identify the dominant noise sources such as engine noise, exhaust noise and noise due to vibration transmission inside of vehicle. The purpose of this paper is to find the vibro-acoustical sources of noise in a passenger vehicle compartment. The implementation of spectral analysis method is much faster than the 'trial and error' methods in which, parts should be separated to measure the transfer functions. Also by using spectral analysis method, signals can be recorded in real operational conditions which conduce to more consistent results. A multi-channel analyser is utilised to measure and record the vibro-acoustical signals. Computational algorithms are also employed to identify contribution of various sources towards the measured interior signal. These achievements can be utilised to detect, control and optimise interior noise performance of road transport vehicles.

  7. When males whistle at females: complex FM acoustic signals in cockroaches

    NASA Astrophysics Data System (ADS)

    Sueur, Jérôme; Aubin, Thierry

    2006-10-01

    Male cockroaches of the species Elliptorhina chopardi expel air through a pair of modified abdominal spiracles during courtship. This air expulsion simultaneously produces air and substrate-borne vibrations. We described and compared in details these two types of vibrations. Our analysis of the air-borne signals shows that males can produce three categories of signals with distinct temporal and frequency parameters. “Pure whistles” consist of two independent harmonic series fast frequency modulated with independent harmonics that can cross each other. “Noisy whistles” also possess two independent voices but include a noisy broad-band frequency part in the middle. Hiss sounds are more noise-like, being made of a broad-band frequency spectrum. All three call types are unusually high in dominant frequency (>5 kHz) for cockroaches. The substrate-borne signals are categorised similarly. Some harmonics of the substrate-borne signals were filtered out, however, making the acoustic energy centered on fewer frequency bands. Our analysis shows that cockroach signals are complex, with fast frequency modulations and two distinct voices. These results also readdress the question of what system could potentially receive and decode the information contained within such complex sounds.

  8. Denoising of human speech using combined acoustic and em sensor signal processing

    SciTech Connect

    Ng, L C; Burnett, G C; Holzrichter, J F; Gable, T J

    1999-11-29

    Low Power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference. This greatly enhances the quality and quantify of information for many speech related applications. See Holzrichter, Burnett, Ng, and Lea, J. Acoustic. Soc. Am. 103 (1) 622 (1998). By using combined Glottal-EM- Sensor- and Acoustic-signals, segments of voiced, unvoiced, and no-speech can be reliably defined. Real-time Denoising filters can be constructed to remove noise from the user's corresponding speech signal.

  9. Acoustic attenuation analysis program for ducts with mean flow

    NASA Technical Reports Server (NTRS)

    Kunze, R. K., Jr.

    1972-01-01

    A computerized acoustic attenuation prediction procedure has been developed to evaluate acoustically lined ducts for various geometric and environmental parameters. The analysis procedure is based on solutions to the acoustic wave equation, assuming uniform airflow on a duct cross section, combined with appropriate mathematical lining impedance models. The impedance models included in the analysis procedure are representative of either perforated sheet or porous polyimide impregnated fiberglass facing sheet coupled with a cellular backing space. Advantages and limitations of the analysis procedure are reviewed.

  10. System And Method For Characterizing Voiced Excitations Of Speech And Acoustic Signals, Removing Acoustic Noise From Speech, And Synthesizi

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2006-04-25

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  11. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2004-03-23

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  12. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2006-02-14

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  13. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2006-08-08

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  14. Monitoring Rock Failure Processes Using the Hilbert-Huang Transform of Acoustic Emission Signals

    NASA Astrophysics Data System (ADS)

    Zhang, Ji; Peng, Weihong; Liu, Fengyu; Zhang, Haixiang; Li, Zhijian

    2016-02-01

    Rock fracturing generates acoustic emission (AE) signals that have statistical parameters referred to as AE signal parameters (AESP). Identification of rock fracturing or the failure process stage using such data raises several challenges. This study proposes a Hilbert-Huang transform-based AE processing approach to capture the time-frequency characteristics of both AE signals and AESP during rock failure processes. The damage occurring in tested rock specimens can be illustrated through analysis using this method. In this study, the specimens were 25 × 60 × 150 mm3 in size and were compressed at a displacement rate of 0.05 mm/min until failure. The recorded data included force and displacement, AE signals, and AESP. The AESP in the last third of the strain range period and 14 typical moments of strong AE signals were selected for further investigation. These results show that AE signals and AESP can be jointly used for identification of deformation stages. The transition between linear and nonlinear deformation stages was found to last for a short period in this process. The instantaneous frequency of the AE effective energy rate increased linearly from 0.5 to 1.5 Hz. Attenuation of elastic waves spreading in rock samples developed with deformation, as illustrated in the Hilbert spectra of AE signals. This attenuation is frequency dependent. Furthermore, AE signals in the softening process showed a complex frequency distribution attributed to the mechanical properties of the tested specimen. The results indicate that rock failure is predictable. The novel technology applied in this study is feasible for analysis of the entire deformation process, including softening and failure processes.

  15. Limited condition dependence of male acoustic signals in the grasshopper Chorthippus biguttulus

    PubMed Central

    Franzke, Alexandra; Reinhold, Klaus

    2012-01-01

    In many animal species, male acoustic signals serve to attract a mate and therefore often play a major role for male mating success. Male body condition is likely to be correlated with male acoustic signal traits, which signal male quality and provide choosy females indirect benefits. Environmental factors such as food quantity or quality can influence male body condition and therefore possibly lead to condition-dependent changes in the attractiveness of acoustic signals. Here, we test whether stressing food plants influences acoustic signal traits of males via condition-dependent expression of these traits. We examined four male song characteristics, which are vital for mate choice in females of the grasshopper Chorthippus biguttulus. Only one of the examined acoustic traits, loudness, was significantly altered by changing body condition because of drought- and moisture-related stress of food plants. No condition dependence could be observed for syllable to pause ratio, gap duration within syllables, and onset accentuation. We suggest that food plant stress and therefore food plant quality led to shifts in loudness of male grasshopper songs via body condition changes. The other three examined acoustic traits of males do not reflect male body condition induced by food plant quality. PMID:22957192

  16. Call Transmission Efficiency in Native and Invasive Anurans: Competing Hypotheses of Divergence in Acoustic Signals

    PubMed Central

    Llusia, Diego; Gómez, Miguel; Penna, Mario; Márquez, Rafael

    2013-01-01

    Invasive species are a leading cause of the current biodiversity decline, and hence examining the major traits favouring invasion is a key and long-standing goal of invasion biology. Despite the prominent role of the advertisement calls in sexual selection and reproduction, very little attention has been paid to the features of acoustic communication of invasive species in nonindigenous habitats and their potential impacts on native species. Here we compare for the first time the transmission efficiency of the advertisement calls of native and invasive species, searching for competitive advantages for acoustic communication and reproduction of introduced taxa, and providing insights into competing hypotheses in evolutionary divergence of acoustic signals: acoustic adaptation vs. morphological constraints. Using sound propagation experiments, we measured the attenuation rates of pure tones (0.2–5 kHz) and playback calls (Lithobates catesbeianus and Pelophylax perezi) across four distances (1, 2, 4, and 8 m) and over two substrates (water and soil) in seven Iberian localities. All factors considered (signal type, distance, substrate, and locality) affected transmission efficiency of acoustic signals, which was maximized with lower frequency sounds, shorter distances, and over water surface. Despite being broadcast in nonindigenous habitats, the advertisement calls of invasive L. catesbeianus were propagated more efficiently than those of the native species, in both aquatic and terrestrial substrates, and in most of the study sites. This implies absence of optimal relationship between native environments and propagation of acoustic signals in anurans, in contrast to what predicted by the acoustic adaptation hypothesis, and it might render these vertebrates particularly vulnerable to intrusion of invasive species producing low frequency signals, such as L. catesbeianus. Our findings suggest that mechanisms optimizing sound transmission in native habitat can play a

  17. Call transmission efficiency in native and invasive anurans: competing hypotheses of divergence in acoustic signals.

    PubMed

    Llusia, Diego; Gómez, Miguel; Penna, Mario; Márquez, Rafael

    2013-01-01

    Invasive species are a leading cause of the current biodiversity decline, and hence examining the major traits favouring invasion is a key and long-standing goal of invasion biology. Despite the prominent role of the advertisement calls in sexual selection and reproduction, very little attention has been paid to the features of acoustic communication of invasive species in nonindigenous habitats and their potential impacts on native species. Here we compare for the first time the transmission efficiency of the advertisement calls of native and invasive species, searching for competitive advantages for acoustic communication and reproduction of introduced taxa, and providing insights into competing hypotheses in evolutionary divergence of acoustic signals: acoustic adaptation vs. morphological constraints. Using sound propagation experiments, we measured the attenuation rates of pure tones (0.2-5 kHz) and playback calls (Lithobates catesbeianus and Pelophylax perezi) across four distances (1, 2, 4, and 8 m) and over two substrates (water and soil) in seven Iberian localities. All factors considered (signal type, distance, substrate, and locality) affected transmission efficiency of acoustic signals, which was maximized with lower frequency sounds, shorter distances, and over water surface. Despite being broadcast in nonindigenous habitats, the advertisement calls of invasive L. catesbeianus were propagated more efficiently than those of the native species, in both aquatic and terrestrial substrates, and in most of the study sites. This implies absence of optimal relationship between native environments and propagation of acoustic signals in anurans, in contrast to what predicted by the acoustic adaptation hypothesis, and it might render these vertebrates particularly vulnerable to intrusion of invasive species producing low frequency signals, such as L. catesbeianus. Our findings suggest that mechanisms optimizing sound transmission in native habitat can play a less

  18. Design and Analysis of Underwater Acoustic Networks with Reflected Links

    NASA Astrophysics Data System (ADS)

    Emokpae, Lloyd

    -of-sight (LOS) and NLOS links by utilizing directional antennas, which will boost the signal-to-noise ratio (SNR) at the receiver while promoting NLOS usage. In our model, we employ a directional underwater acoustic antenna composed of an array of hydrophones that can be summed up at various phases and amplitudes resulting in a beam-former. We have also adopted a practical multimodal directional transducer concept which generates both directional and omni-directional beam patterns by combining the fundamental vibration modes of a cylindrical acoustic radiator. This allows the transducer to be electrically controlled and steered by simply adjusting the electrical voltage weights. A prototype acoustic modem is then developed to utilize the multimodal directional transducer for both LOS and NLOS communication. The acoustic modem has also been used as a platform for empirically validating our SBR communication model in a tank and with empirical data. Networking protocols have been developed to exploit the SBR communication model. These protocols include node discovery and localization, directional medium access control (D-MAC) and geographical routing. In node discovery and localization, each node will utilize SBR-based range measurements to its neighbors to determine their relative position. The D-MAC protocol utilizes directional antennas to increase the network throughput due to the spatial efficiency of the antenna model. In the proposed reflection-enabled directional MAC protocol (RED-MAC), each source node will be able to determine if an obstacle is blocking the LOS link to the destination and switch to the best NLOS link by utilizing surface/bottom reflections. Finally, we have developed a geographical routing algorithm which aims to establish the best stable route from a source node to a destination node. The optimized route is selected to achieve maximum network throughput. Extensive analysis of the network throughput when utilizing directional antennas is also presented

  19. Silent katydid females are at higher risk of bat predation than acoustically signalling katydid males

    PubMed Central

    Raghuram, Hanumanthan; Deb, Rittik; Nandi, Diptarup; Balakrishnan, Rohini

    2015-01-01

    Males that produce conspicuous mate attraction signals are often at high risk of predation from eavesdropping predators. Females of such species typically search for signalling males and their higher motility may also place them at risk. The relative predation risk faced by males and females in the context of mate-finding using long-distance signals has rarely been investigated. In this study, we show, using a combination of diet analysis and behavioural experiments, that katydid females, who do not produce acoustic signals, are at higher risk of predation from a major bat predator, Megaderma spasma, than calling males. Female katydids were represented in much higher numbers than males in the culled remains beneath roosts of M. spasma. Playback experiments using katydid calls revealed that male calls were approached in only about one-third of the trials overall, whereas tethered, flying katydids were always approached and attacked. Our results question the idea that necessary costs of mate-finding, including risk of predation, are higher in signalling males than in searching females. PMID:25429019

  20. Silent katydid females are at higher risk of bat predation than acoustically signalling katydid males.

    PubMed

    Raghuram, Hanumanthan; Deb, Rittik; Nandi, Diptarup; Balakrishnan, Rohini

    2015-01-01

    Males that produce conspicuous mate attraction signals are often at high risk of predation from eavesdropping predators. Females of such species typically search for signalling males and their higher motility may also place them at risk. The relative predation risk faced by males and females in the context of mate-finding using long-distance signals has rarely been investigated. In this study, we show, using a combination of diet analysis and behavioural experiments, that katydid females, who do not produce acoustic signals, are at higher risk of predation from a major bat predator, Megaderma spasma, than calling males. Female katydids were represented in much higher numbers than males in the culled remains beneath roosts of M. spasma. Playback experiments using katydid calls revealed that male calls were approached in only about one-third of the trials overall, whereas tethered, flying katydids were always approached and attacked. Our results question the idea that necessary costs of mate-finding, including risk of predation, are higher in signalling males than in searching females. PMID:25429019

  1. Implementing wavelet packet transform for valve failure detection using vibration and acoustic emission signals

    NASA Astrophysics Data System (ADS)

    Sim, H. Y.; Ramli, R.; Abdullah, M. A. K.

    2012-05-01

    The efficiency of reciprocating compressors relies heavily on the health condition of its moving components, most importantly its valves. Previous studies showed good correlation between the dynamic response and the physical condition of the valves. These can be achieved by employing vibration technique which is capable of monitoring the response of the valve, and acoustic emission technique which is capable of detecting the valves' material deformation. However, the relationship/comparison between the two techniques is rarely investigated. In this paper, the two techniques were examined using time-frequency analysis. Wavelet packet transform (WPT) was chosen as the multi-resolution analysis technique over continuous wavelet transform (CWT), and discrete wavelet transform (DWT). This is because WPT could overcome the high computational time and high redundancy problem in CWT and could provide detailed analysis of the high frequency components compared to DWT. The features of both signals can be extracted by evaluating the normalised WPT coefficients for different time window under different valve conditions. By comparing the normalised coefficients over a certain time frame and frequency range, the feature vectors revealing the condition of valves can be constructed. One way analysis of variance was employed on these feature vectors to test the significance of data under different valve conditions. It is believed that AE signals can give a better representation of the valve condition as it can detect both the fluid motion and material deformation of valves as compared to the vibration signals.

  2. Acoustical analysis of gear housing vibration

    NASA Technical Reports Server (NTRS)

    Seybert, A. F.; Wu, T. W.; Wu, X. F.; Oswald, Fred B.

    1991-01-01

    The modal and acoustical analysis of the NASA gear-noise rig is described. Experimental modal analysis techniques were used to determine the modes of vibration of the transmission housing. The resulting modal data were then used in a boundary element method (BEM) analysis to calculate the sound pressure and sound intensity on the surface of the housing as well as the radiation efficiency of each mode. The radiation efficiencies of the transmission housing modes are compared with theoretical results for finite, baffled plates. A method that uses the measured mode shapes and the BEM to predict the effect of simple structural changes on the sound radiation efficiency of the modes of vibration is also described.

  3. Signal recovery technique based on a physical method of underwater acoustics

    NASA Astrophysics Data System (ADS)

    Guo, Xinyi; Wu, Guoqing; Ma, Li

    2010-09-01

    In the underwater sound channel we often use an array to receive signals from distant sources. The received signals are often mixed with environmental interference. In the complex acoustic environment, received signals are distorted greatly and elongated in time. In many practical applications such as sound communications, sound remote sensing and active sonar signals, we hope to obtain the original signal's waveform. In general theory, the received signals are the convolution of emission signals and Green's function of environment. In unknown Green's function of environment, simply relying on the array to record the information to determine the sound source signal wave propagation features and the environment is not enough. However, in certain circumstances, based on a physics method of underwater acoustics, the spread of recovery technology is successful.

  4. Particle analysis in an acoustic cytometer

    DOEpatents

    Kaduchak, Gregory; Ward, Michael D

    2012-09-18

    The present invention is a method and apparatus for acoustically manipulating one or more particles. Acoustically manipulated particles may be separated by size. The particles may be flowed in a flow stream and acoustic radiation pressure, which may be radial, may be applied to the flow stream. This application of acoustic radiation pressure may separate the particles. In one embodiment, the particles may be separated by size, and as a further example, the larger particles may be transported to a central axis.

  5. Dolphin's echolocation signals in a complicated acoustic environment

    NASA Astrophysics Data System (ADS)

    Ivanov, M. P.

    2004-07-01

    Echolocation abilities of a dolphin ( Tursiops truncatus ponticus) were investigated in laboratory conditions. The experiment was carried out in an open cage using an acoustic control over the behavior of the animal detecting underwater objects in a complicated acoustic environment. Targets of different strength were used as test objects. The dolphin was found to be able to detect objects at distances exceeding 650 m. For the target location, the dolphin used both single-pulse and multipulse echolocation modes. Time characteristics of echolocation pulses and time sequences of pulses as functions of the distance to the target were obtained.

  6. An information processing method for acoustic emission signal inspired from musical staff

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Wu, Chunxian

    2016-01-01

    This study proposes a musical-staff-inspired signal processing method for standard description expressions for discrete signals and describing the integrated characteristics of acoustic emission (AE) signals. The method maps various AE signals with complex environments into the normalized musical space. Four new indexes are proposed to comprehensively describe the signal. Several key features, such as contour, amplitude, and signal changing rate, are quantitatively expressed in a normalized musical space. The processed information requires only a small storage space to maintain high fidelity. The method is illustrated by using experiments on sandstones and computed tomography (CT) scanning to determine its validity for AE signal processing.

  7. System and method for investigating sub-surface features of a rock formation with acoustic sources generating coded signals

    SciTech Connect

    Vu, Cung Khac; Nihei, Kurt; Johnson, Paul A; Guyer, Robert; Ten Cate, James A; Le Bas, Pierre-Yves; Larmat, Carene S

    2014-12-30

    A system and a method for investigating rock formations includes generating, by a first acoustic source, a first acoustic signal comprising a first plurality of pulses, each pulse including a first modulated signal at a central frequency; and generating, by a second acoustic source, a second acoustic signal comprising a second plurality of pulses. A receiver arranged within the borehole receives a detected signal including a signal being generated by a non-linear mixing process from the first-and-second acoustic signal in a non-linear mixing zone within the intersection volume. The method also includes-processing the received signal to extract the signal generated by the non-linear mixing process over noise or over signals generated by a linear interaction process, or both.

  8. Perceptual centres in speech - an acoustic analysis

    NASA Astrophysics Data System (ADS)

    Scott, Sophie Kerttu

    Perceptual centres, or P-centres, represent the perceptual moments of occurrence of acoustic signals - the 'beat' of a sound. P-centres underlie the perception and production of rhythm in perceptually regular speech sequences. P-centres have been modelled both in speech and non speech (music) domains. The three aims of this thesis were toatest out current P-centre models to determine which best accounted for the experimental data bto identify a candidate parameter to map P-centres onto (a local approach) as opposed to the previous global models which rely upon the whole signal to determine the P-centre the final aim was to develop a model of P-centre location which could be applied to speech and non speech signals. The first aim was investigated by a series of experiments in which a) speech from different speakers was investigated to determine whether different models could account for variation between speakers b) whether rendering the amplitude time plot of a speech signal affects the P-centre of the signal c) whether increasing the amplitude at the offset of a speech signal alters P-centres in the production and perception of speech. The second aim was carried out by a) manipulating the rise time of different speech signals to determine whether the P-centre was affected, and whether the type of speech sound ramped affected the P-centre shift b) manipulating the rise time and decay time of a synthetic vowel to determine whether the onset alteration was had more affect on P-centre than the offset manipulation c) and whether the duration of a vowel affected the P-centre, if other attributes (amplitude, spectral contents) were held constant. The third aim - modelling P-centres - was based on these results. The Frequency dependent Amplitude Increase Model of P-centre location (FAIM) was developed using a modelling protocol, the APU GammaTone Filterbank and the speech from different speakers. The P-centres of the stimuli corpus were highly predicted by attributes of

  9. Corruption of ant acoustical signals by mimetic social parasites

    PubMed Central

    Schönrogge, Karsten; Bonelli, Simona; Barbero, Francesca; Balletto, Emilio

    2010-01-01

    Recent recordings of the stridulations of Myrmica ants revealed that their queens made distinctive sounds from their workers, although the acoustics of queens and workers, respectively, were the same in different species of Myrmica. Queen recordings induced enhanced protective behavior when played to workers in the one species tested. Larvae and pupae of the butterfly genus Maculinea inhabit Myrmica colonies as social parasites, and both stages generate sounds that mimic those of a Myrmica queen, inducing similar superior treatments from workers as their model. We discuss how initial penetration and acceptance as a colony member is achieved by Maculinea through mimicking the species-specific semio-chemicals of their hosts, and how acoustical mimicry is then employed to elevate the parasite’s membership of that society towards the highest attainable level in their host’s hierarchy. We postulate that, if acoustics is as well developed a means of communication in certain ants as these studies suggest, then others among an estimated 10,000 species of ant social parasite may supplement their well-known use of chemical and tactile mimicry to trick host ants with mimicry of host acoustical systems. PMID:20585513

  10. Copula filtration of spoken language signals on the background of acoustic noise

    NASA Astrophysics Data System (ADS)

    Kolchenko, Lilia V.; Sinitsyn, Rustem B.

    2010-09-01

    This paper is devoted to the filtration of acoustic signals on the background of acoustic noise. Signal filtering is done with the help of a nonlinear analogue of a correlation function - a copula. The copula is estimated with the help of kernel estimates of the cumulative distribution function. At the second stage we suggest a new procedure of adaptive filtering. The silence and sound intervals are detected before the filtration with the help of nonparametric algorithm. The results are confirmed by experimental processing of spoken language signals.

  11. Forward model of thermally-induced acoustic signal specific to intralumenal detection geometry

    NASA Astrophysics Data System (ADS)

    Mukherjee, Sovanlal; Bunting, Charles F.; Piao, Daqing

    2011-03-01

    This work investigates a forward model associated with intra-lumenal detection of acoustic signal originated from transient thermal-expansion of the tissue. The work is specific to intra-lumenal thermo-acoustic tomography (TAT) which detects the contrast of tissue dielectric properties with ultrasonic resolution, but it is also extendable to intralumenal photo-acoustic tomography (PAT) which detects the contrast of light absorption properties of tissue with ultrasound resolution. Exact closed-form frequency-domain or time-domain forward model of thermally-induced acoustic signal have been studied rigorously for planar geometry and two other geometries, including cylindrical and spherical geometries both of which is specific to external-imaging, i.e. breast or brain imaging using an externally-deployed applicator. This work extends the existing studies to the specific geometry of internal or intra-lumenal imaging, i.e., prostate imaging by an endo-rectally deployed applicator. In this intra-lumenal imaging geometry, both the source that excites the transient thermal-expansion of the tissue and the acoustic transducer that acquires the thermally-induced acoustic signal are assumed enclosed by the tissue and on the surface of a long cylindrical applicator. The Green's function of the frequency-domain thermo-acoustic equation in spherical coordinates is expanded to cylindrical coordinates associated with intra-lumenal geometry. Inverse Fourier transform is then applied to obtain a time-domain solution of the thermo-acoustic pressure wave for intra-lumenal geometry. Further employment of the boundary condition to the "convex" applicator-tissue interface would render an exact forward solution toward accurate reconstruction for intra-lumenal thermally-induced acoustic imaging.

  12. Characterizing, synthesizing, and/or canceling out acoustic signals from sound sources

    DOEpatents

    Holzrichter, John F.; Ng, Lawrence C.

    2007-03-13

    A system for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate and animate sound sources. Electromagnetic sensors monitor excitation sources in sound producing systems, such as animate sound sources such as the human voice, or from machines, musical instruments, and various other structures. Acoustical output from these sound producing systems is also monitored. From such information, a transfer function characterizing the sound producing system is generated. From the transfer function, acoustical output from the sound producing system may be synthesized or canceled. The systems disclosed enable accurate calculation of transfer functions relating specific excitations to specific acoustical outputs. Knowledge of such signals and functions can be used to effect various sound replication, sound source identification, and sound cancellation applications.

  13. Sources and Radiation Patterns of Volcano-Acoustic Signals Investigated with Field-Scale Chemical Explosions

    NASA Astrophysics Data System (ADS)

    Bowman, D. C.; Lees, J. M.; Taddeucci, J.; Graettinger, A. H.; Sonder, I.; Valentine, G.

    2014-12-01

    We investigate the processes that give rise to complex acoustic signals during volcanic blasts by monitoring buried chemical explosions with infrasound and audio range microphones, strong motion sensors, and high speed imagery. Acoustic waveforms vary with scaled depth of burial (SDOB, units in meters per cube root of joules), ranging from high amplitude, impulsive, gas expansion dominated signals at low SDOB to low amplitude, longer duration, ground motion dominated signals at high SDOB. Typically, the sudden upward acceleration of the substrate above the blast produces the first acoustic arrival, followed by a second pulse due to the eruption of pressurized gas at the surface. Occasionally, a third overpressure occurs when displaced material decelerates upon impact with the ground. The transition between ground motion dominated and gas release dominated acoustics ranges between 0.0038-0.0018 SDOB, respectively. For example, one explosion registering an SDOB=0.0031 produced two overpressure pulses of approximately equal amplitude, one due to ground motion, the other to gas release. Recorded volcano infrasound has also identified distinct ground motion and gas release components during explosions at Sakurajima, Santiaguito, and Karymsky volcanoes. Our results indicate that infrasound records may provide a proxy for the depth and energy of these explosions. Furthermore, while magma fragmentation models indicate the possibility of several explosions during a single vulcanian eruption (Alidibirov, Bull Volc., 1994), our results suggest that a single explosion can also produce complex acoustic signals. Thus acoustic records alone cannot be used to distinguish between single explosions and multiple closely-spaced blasts at volcanoes. Results from a series of lateral blasts during the 2014 field experiment further indicates whether vent geometry can produce directional acoustic radiation patterns like those observed at Tungarahua volcano (Kim et al., GJI, 2012). Beside

  14. Modal analysis and intensity of acoustic radiation of the kettledrum.

    PubMed

    Tronchin, Lamberto

    2005-02-01

    The acoustical features of kettledrums have been analyzed by means of modal analysis and acoustic radiation (p/v ratio) measurements. Modal analysis of two different kettledrums was undertaken, exciting the system both by a hammer and a shaker. Up to 15 vibrational modes were clearly identified. Acoustic radiation was studied using two ways. Based on previous experiments of other researchers, a new parameter, called intensity of acoustic radiation (IAR), has been defined and measured. Results show a strict relationship between IAR and the frequency response function (FRF, which is the v/F ratio), and IAR also strongly relates the modal pattern to acoustic radiation. Finally, IAR is proposed for vibro-acoustical characterization of kettledrums and other musical instruments such as strings, pianos, and harpsichords. PMID:15759711

  15. Deciphering acoustic emission signals in drought stressed branches: the missing link between source and sensor.

    PubMed

    Vergeynst, Lidewei L; Sause, Markus G R; Hamstad, Marvin A; Steppe, Kathy

    2015-01-01

    When drought occurs in plants, acoustic emission (AE) signals can be detected, but the actual causes of these signals are still unknown. By analyzing the waveforms of the measured signals, it should, however, be possible to trace the characteristics of the AE source and get information about the underlying physiological processes. A problem encountered during this analysis is that the waveform changes significantly from source to sensor and lack of knowledge on wave propagation impedes research progress made in this field. We used finite element modeling and the well-known pencil lead break source to investigate wave propagation in a branch. A cylindrical rod of polyvinyl chloride was first used to identify the theoretical propagation modes. Two wave propagation modes could be distinguished and we used the finite element model to interpret their behavior in terms of source position for both the PVC rod and a wooden rod. Both wave propagation modes were also identified in drying-induced signals from woody branches, and we used the obtained insights to provide recommendations for further AE research in plant science. PMID:26191070

  16. Deciphering acoustic emission signals in drought stressed branches: the missing link between source and sensor

    PubMed Central

    Vergeynst, Lidewei L.; Sause, Markus G. R.; Hamstad, Marvin A.; Steppe, Kathy

    2015-01-01

    When drought occurs in plants, acoustic emission (AE) signals can be detected, but the actual causes of these signals are still unknown. By analyzing the waveforms of the measured signals, it should, however, be possible to trace the characteristics of the AE source and get information about the underlying physiological processes. A problem encountered during this analysis is that the waveform changes significantly from source to sensor and lack of knowledge on wave propagation impedes research progress made in this field. We used finite element modeling and the well-known pencil lead break source to investigate wave propagation in a branch. A cylindrical rod of polyvinyl chloride was first used to identify the theoretical propagation modes. Two wave propagation modes could be distinguished and we used the finite element model to interpret their behavior in terms of source position for both the PVC rod and a wooden rod. Both wave propagation modes were also identified in drying-induced signals from woody branches, and we used the obtained insights to provide recommendations for further AE research in plant science. PMID:26191070

  17. The Acoustic Signal of a Helicopter can be Used to Track it With Seismic Arrays

    NASA Astrophysics Data System (ADS)

    Eibl, Eva P. S.; Lokmer, Ivan; Bean, Christopher J.; Akerlie, Eggert

    2016-04-01

    We apply traditional frequency domain methods usually applied to volcanic tremor on seismic recordings of a helicopter. On a volcano the source can be repeating, closely spaced earthquakes whereas for a helicopter the source are repeating pressure pulses from the rotor blades that are converted through acoustic-to-seismic coupling. In both cases the seismic signal is referred to as tremor. As frequency gliding is in this case merely caused by the Doppler effect, not a change in the source, we can use its shape to deduce properties of the helicopter. We show in this analysis that the amount of rotor blades, rotor revolutions per minute (RPM), flight direction, height and location can be deduced. The signal was recorded by a seven station broadband array with an aperture of 1.6 km. Our spacing is close enough to record the signal at all stations and far enough to observe traveltime differences. We perform a detailed spectral and location analysis of the signal, and compare our results with the known information on the helicopter's speed, location, height, the frequency of the blades rotation and the amount of blades. This analysis is based on the characteristic shape of the curve i.e. speed of the gliding, minimum and maximum fundamental frequency, amplitudes at the inflection points at different stations and traveltimes deduced from the inflection points at different stations. The helicopter GPS track gives us a robust way of testing the method. This observation has an educative value, because the same principles can be applied to signals in different disciplines.

  18. Acoustic and ultrasonic signals as diagnostic tools for check valves

    SciTech Connect

    Auyang, M.K. )

    1993-05-01

    A typical nuclear plant has between 60 and 115 safety-related check valves ranging from 2 to 30 in. The majority of these valves control water flow. Recent studies done by the Institute of Nuclear Power Operations (INPO), Electric Power Research Institute (EPRI) and the US Nuclear Regulatory Commission (NRC) found that many of these safety-related valves were not functioning properly. Typical problems found in these valves included disk flutter, backstop tapping, flow leakage, disk pin and hinge pin wear, or even missing disks. These findings led to INPO's Significant Operating Experience Report (SOER, 1986), and finally, NRC generic letter 8904, which requires that all safety-related check valves in a nuclear plant be regularly monitored. In response to this need, the industry has developed various diagnostic equipment to monitor and test check valves, using technologies ranging from acoustics and ultrasonics to magnetic - even radiography has been considered. Of these, systems that depend on a combination of acoustic and ultrasonic techniques are among the most promising for two reasons: these two technologies supplement each other, making diagnosis of the check valves much more certain than any single technology, and this approach can be made nonintrusive. The nonintrusive feature allows the check valves to be monitored and diagnosed without being disassembled or removed from the piping system. This paper shows that by carefully studying the acoustic and ultrasonic signatures acquired from a check value, either individually or in combination, an individual with the proper training and experience in acoustic and ultrasonic signature analyses can deduce the structural integrity of the check valve with good confidence. Most of the conclusions are derived from controlled experiments in the laboratory where the diagnosis can be verified. Other conclusions were based on test data obtained in the field.

  19. Acoustic analysis of speech under stress.

    PubMed

    Sondhi, Savita; Khan, Munna; Vijay, Ritu; Salhan, Ashok K; Chouhan, Satish

    2015-01-01

    When a person is emotionally charged, stress could be discerned in his voice. This paper presents a simplified and a non-invasive approach to detect psycho-physiological stress by monitoring the acoustic modifications during a stressful conversation. Voice database consists of audio clips from eight different popular FM broadcasts wherein the host of the show vexes the subjects who are otherwise unaware of the charade. The audio clips are obtained from real-life stressful conversations (no simulated emotions). Analysis is done using PRAAT software to evaluate mean fundamental frequency (F0) and formant frequencies (F1, F2, F3, F4) both in neutral and stressed state. Results suggest that F0 increases with stress; however, formant frequency decreases with stress. Comparison of Fourier and chirp spectra of short vowel segment shows that for relaxed speech, the two spectra are similar; however, for stressed speech, they differ in the high frequency range due to increased pitch modulation. PMID:26558301

  20. Classification of acoustic emission signals using wavelets and Random Forests : Application to localized corrosion

    NASA Astrophysics Data System (ADS)

    Morizet, N.; Godin, N.; Tang, J.; Maillet, E.; Fregonese, M.; Normand, B.

    2016-03-01

    This paper aims to propose a novel approach to classify acoustic emission (AE) signals deriving from corrosion experiments, even if embedded into a noisy environment. To validate this new methodology, synthetic data are first used throughout an in-depth analysis, comparing Random Forests (RF) to the k-Nearest Neighbor (k-NN) algorithm. Moreover, a new evaluation tool called the alter-class matrix (ACM) is introduced to simulate different degrees of uncertainty on labeled data for supervised classification. Then, tests on real cases involving noise and crevice corrosion are conducted, by preprocessing the waveforms including wavelet denoising and extracting a rich set of features as input of the RF algorithm. To this end, a software called RF-CAM has been developed. Results show that this approach is very efficient on ground truth data and is also very promising on real data, especially for its reliability, performance and speed, which are serious criteria for the chemical industry.

  1. A framework for the damage evaluation of acoustic emission signals through Hilbert-Huang transform

    NASA Astrophysics Data System (ADS)

    Siracusano, Giulio; Lamonaca, Francesco; Tomasello, Riccardo; Garescì, Francesca; Corte, Aurelio La; Carnì, Domenico Luca; Carpentieri, Mario; Grimaldi, Domenico; Finocchio, Giovanni

    2016-06-01

    The acoustic emission (AE) is a powerful and potential nondestructive testing method for structural monitoring in civil engineering. Here, we show how systematic investigation of crack phenomena based on AE data can be significantly improved by the use of advanced signal processing techniques. Such data are a fundamental source of information that can be used as the basis for evaluating the status of the material, thereby paving the way for a new frontier of innovation made by data-enabled analytics. In this article, we propose a framework based on the Hilbert-Huang Transform for the evaluation of material damages that (i) facilitates the systematic employment of both established and promising analysis criteria, and (ii) provides unsupervised tools to achieve an accurate classification of the fracture type, the discrimination between longitudinal (P-) and traversal (S-) waves related to an AE event. The experimental validation shows promising results for a reliable assessment of the health status through the monitoring of civil infrastructures.

  2. The Effect of Habitat Acoustics on Common Marmoset Vocal Signal Transmission

    PubMed Central

    MORRILL, RYAN J.; THOMAS, A. WREN; SCHIEL, NICOLA; SOUTO, ANTONIO; MILLER, CORY T.

    2013-01-01

    Noisy acoustic environments present several challenges for the evolution of acoustic communication systems. Among the most significant is the need to limit degradation of spectro-temporal signal structure in order to maintain communicative efficacy. This can be achieved by selecting for several potentially complementary processes. Selection can act on behavioral mechanisms permitting signalers to control the timing and occurrence of signal production to avoid acoustic interference. Likewise, the signal itself may be the target of selection, biasing the evolution of its structure to comprise acoustic features that avoid interference from ambient noise or degrade minimally in the habitat. Here, we address the latter topic for common marmoset (Callithrix jacchus) long-distance contact vocalizations, known as phee calls. Our aim was to test whether this vocalization is specifically adapted for transmission in a species-typical forest habitat, the Atlantic forests of northeastern Brazil. We combined seasonal analyses of ambient habitat acoustics with experiments in which pure tones, clicks, and vocalizations were broadcast and rerecorded at different distances to characterize signal degradation in the habitat. Ambient sound was analyzed from intervals throughout the day and over rainy and dry seasons, showing temporal regularities across varied timescales. Broadcast experiment results indicated that the tone and click stimuli showed the typically inverse relationship between frequency and signaling efficacy. Although marmoset phee calls degraded over distance with marked predictability compared with artificial sounds, they did not otherwise appear to be specially designed for increased transmission efficacy or minimal interference in this habitat. We discuss these data in the context of other similar studies and evidence of potential behavioral mechanisms for avoiding acoustic interference in order to maintain effective vocal communication in common marmosets. PMID

  3. System and method for investigating sub-surface features of a rock formation with acoustic sources generating conical broadcast signals

    DOEpatents

    Vu, Cung Khac; Skelt, Christopher; Nihei, Kurt; Johnson, Paul A.; Guyer, Robert; Ten Cate, James A.; Le Bas, Pierre -Yves; Larmat, Carene S.

    2015-08-18

    A method of interrogating a formation includes generating a conical acoustic signal, at a first frequency--a second conical acoustic signal at a second frequency each in the between approximately 500 Hz and 500 kHz such that the signals intersect in a desired intersection volume outside the borehole. The method further includes receiving, a difference signal returning to the borehole resulting from a non-linear mixing of the signals in a mixing zone within the intersection volume.

  4. Beeping and piping: characterization of two mechano-acoustic signals used by honey bees in swarming.

    PubMed

    Schlegel, Thomas; Visscher, P Kirk; Seeley, Thomas D

    2012-12-01

    Of the many signals used by honey bees during the process of swarming, two of them--the stop signal and the worker piping signal--are not easily distinguished for both are mechano-acoustic signals produced by scout bees who press their bodies against other bees while vibrating their wing muscles. To clarify the acoustic differences between these two signals, we recorded both signals from the same swarm and at the same time, and compared them in terms of signal duration, fundamental frequency, and frequency modulation. Stop signals and worker piping signals differ in all three variables: duration, 174 ± 64 vs. 602 ± 377 ms; fundamental frequency, 407 vs. 451 Hz; and frequency modulation, absent vs. present. While it remains unclear which differences the bees use to distinguish the two signals, it is clear that they do so for the signals have opposite effects. Stop signals cause inhibition of actively dancing scout bees whereas piping signals cause excitation of quietly resting non-scout bees. PMID:23149930

  5. Estimation of glottal source features from the spectral envelope of the acoustic speech signal

    NASA Astrophysics Data System (ADS)

    Torres, Juan Felix

    Speech communication encompasses diverse types of information, including phonetics, affective state, voice quality, and speaker identity. From a speech production standpoint, the acoustic speech signal can be mainly divided into glottal source and vocal tract components, which play distinct roles in rendering the various types of information it contains. Most deployed speech analysis systems, however, do not explicitly represent these two components as distinct entities, as their joint estimation from the acoustic speech signal becomes an ill-defined blind deconvolution problem. Nevertheless, because of the desire to understand glottal behavior and how it relates to perceived voice quality, there has been continued interest in explicitly estimating the glottal component of the speech signal. To this end, several inverse filtering (IF) algorithms have been proposed, but they are unreliable in practice because of the blind formulation of the separation problem. In an effort to develop a method that can bypass the challenging IF process, this thesis proposes a new glottal source information extraction method that relies on supervised machine learning to transform smoothed spectral representations of speech, which are already used in some of the most widely deployed and successful speech analysis applications, into a set of glottal source features. A transformation method based on Gaussian mixture regression (GMR) is presented and compared to current IF methods in terms of feature similarity, reliability, and speaker discrimination capability on a large speech corpus, and potential representations of the spectral envelope of speech are investigated for their ability represent glottal source variation in a predictable manner. The proposed system was found to produce glottal source features that reasonably matched their IF counterparts in many cases, while being less susceptible to spurious errors. The development of the proposed method entailed a study into the aspects

  6. Frequency Characteristics of Acoustic Emission Signals from Cementitious Waste-forms with Encapsulated Al

    SciTech Connect

    Spasova, Lyubka M.; Ojovan, Michael I.

    2007-07-01

    Acoustic emission (AE) signals were continuously recorded and their intrinsic frequency characteristics examined in order to evaluate the mechanical performance of cementitious wasteform samples with encapsulated Al waste. The primary frequency in the power spectrum and its range of intensity for the detected acoustic waves were potentially related with appearance of different micro-mechanical events caused by Al corrosion within the encapsulating cement system. In addition the process of cement matrix hardening has been shown as a source of AE signals characterized with essentially higher primary frequency (above 2 MHz) compared with those due to Al corrosion development (below 40 kHz) and cement cracking (above 100 kHz). (authors)

  7. Search for acoustic signals from high energy cascades

    NASA Technical Reports Server (NTRS)

    Bell, R.; Bowen, T.

    1985-01-01

    High energy cosmic ray secondaries can be detected by means of the cascades they produce when they pass through matter. When the charged particles of these cascades ionize the matter they are traveling through, the heat produced and resulting thermal expansion causes a thermoacoustic wave. These sound waves travel at about one hundred-thousandth the speed of light, and should allow an array of acoustic transducers to resolve structure in the cascade to about 1 cm without high speed electronics or segmentation of the detector.

  8. Research on power-law acoustic transient signal detection based on wavelet transform

    NASA Astrophysics Data System (ADS)

    Han, Jian-hui; Yang, Ri-jie; Wang, Wei

    2007-11-01

    Aiming at the characteristics of acoustic transient signal emitted from antisubmarine weapon which is being dropped into water (torpedo, aerial sonobuoy and rocket assisted depth charge etc.), such as short duration, low SNR, abruptness and instability, based on traditional power-law detector, a new method to detect acoustic transient signal is proposed. Firstly wavelet transform is used to de-noise signal, removes random spectrum components and improves SNR. Then Power- Law detector is adopted to detect transient signal. The simulation results show the method can effectively extract envelop characteristic of transient signal on the condition of low SNR. The performance of WT-Power-Law markedly outgoes that of traditional Power-Law detection method.

  9. Usage Autocorrelation Function in the Capacity of Indicator Shape of the Signal in Acoustic Emission Testing of Intricate Castings

    NASA Astrophysics Data System (ADS)

    Popkov, Artem

    2016-01-01

    The article contains information about acoustic emission signals analysing using autocorrelation function. Operation factors were analysed, such as shape of signal, the origins time and carrier frequency. The purpose of work is estimating the validity of correlations methods analysing signals. Acoustic emission signal consist of different types of waves, which propagate on different trajectories in object of control. Acoustic emission signal is amplitude-, phase- and frequency-modeling signal. It was described by carrier frequency at a given point of time. Period of signal make up 12.5 microseconds and carrier frequency make up 80 kHz for analysing signal. Usage autocorrelation function like indicator the origin time of acoustic emission signal raises validity localization of emitters.

  10. Acoustic Analysis of Vowels Following Glossectomy

    ERIC Educational Resources Information Center

    Whitehill, Tara L.; Ciocca, Valter; Chan, Judy C-T.; Samman, Nabil

    2006-01-01

    This study examined the acoustic characteristics of vowels produced by speakers with partial glossectomy. Acoustic variables investigated included first formant (F1) frequency, second formant (F2) frequency, F1 range, F2 range and vowel space area. Data from the speakers with partial glossectomy were compared with age- and gender-matched controls.…

  11. Beeping and piping: characterization of two mechano-acoustic signals used by honey bees in swarming

    NASA Astrophysics Data System (ADS)

    Schlegel, Thomas; Visscher, P. Kirk; Seeley, Thomas D.

    2012-12-01

    Of the many signals used by honey bees during the process of swarming, two of them—the stop signal and the worker piping signal—are not easily distinguished for both are mechano-acoustic signals produced by scout bees who press their bodies against other bees while vibrating their wing muscles. To clarify the acoustic differences between these two signals, we recorded both signals from the same swarm and at the same time, and compared them in terms of signal duration, fundamental frequency, and frequency modulation. Stop signals and worker piping signals differ in all three variables: duration, 174 ± 64 vs. 602 ± 377 ms; fundamental frequency, 407 vs. 451 Hz; and frequency modulation, absent vs. present. While it remains unclear which differences the bees use to distinguish the two signals, it is clear that they do so for the signals have opposite effects. Stop signals cause inhibition of actively dancing scout bees whereas piping signals cause excitation of quietly resting non-scout bees.

  12. Wayside acoustic diagnosis of defective train bearings based on signal resampling and information enhancement

    NASA Astrophysics Data System (ADS)

    He, Qingbo; Wang, Jun; Hu, Fei; Kong, Fanrang

    2013-10-01

    The diagnosis of train bearing defects plays a significant role to maintain the safety of railway transport. Among various defect detection techniques, acoustic diagnosis is capable of detecting incipient defects of a train bearing as well as being suitable for wayside monitoring. However, the wayside acoustic signal will be corrupted by the Doppler effect and surrounding heavy noise. This paper proposes a solution to overcome these two difficulties in wayside acoustic diagnosis. In the solution, a dynamically resampling method is firstly presented to reduce the Doppler effect, and then an adaptive stochastic resonance (ASR) method is proposed to enhance the defective characteristic frequency automatically by the aid of noise. The resampling method is based on a frequency variation curve extracted from the time-frequency distribution (TFD) of an acoustic signal by dynamically minimizing the local cost functions. For the ASR method, the genetic algorithm is introduced to adaptively select the optimal parameter of the multiscale noise tuning (MST)-based stochastic resonance (SR) method. The proposed wayside acoustic diagnostic scheme combines signal resampling and information enhancement, and thus is expected to be effective in wayside defective bearing detection. The experimental study verifies the effectiveness of the proposed solution.

  13. Effect of reflected and refracted signals on coherent underwater acoustic communication: results from the Kauai experiment (KauaiEx 2003).

    PubMed

    Rouseff, Daniel; Badiey, Mohsen; Song, Aijun

    2009-11-01

    The performance of a communications equalizer is quantified in terms of the number of acoustic paths that are treated as usable signal. The analysis uses acoustical and oceanographic data collected off the Hawaiian Island of Kauai. Communication signals were measured on an eight-element vertical array at two different ranges, 1 and 2 km, and processed using an equalizer based on passive time-reversal signal processing. By estimating the Rayleigh parameter, it is shown that all paths reflected by the sea surface at both ranges undergo incoherent scattering. It is demonstrated that some of these incoherently scattered paths are still useful for coherent communications. At range of 1 km, optimal communications performance is achieved when six acoustic paths are retained and all paths with more than one reflection off the sea surface are rejected. Consistent with a model that ignores loss from near-surface bubbles, the performance improves by approximately 1.8 dB when increasing the number of retained paths from four to six. The four-path results though are more stable and require less frequent channel estimation. At range of 2 km, ray refraction is observed and communications performance is optimal when some paths with two sea-surface reflections are retained. PMID:19894819

  14. Mode tomography using signals from the Long Range Ocean Acoustic Propagation EXperiment (LOAPEX)

    NASA Astrophysics Data System (ADS)

    Chandrayadula, Tarun K.

    Ocean acoustic tomography uses acoustic signals to infer the environmental properties of the ocean. The procedure for tomography consists of low frequency acoustic transmissions at mid-water depths to receivers located at hundreds of kilometer ranges. The arrival times of the signal at the receiver are then inverted for the sound speed of the background environment. Using this principle, experiments such as the 2004 Long Range Ocean Acoustic Propagation EXperiment have used acoustic signals recorded across Vertical Line Arrays (VLAs) to infer the Sound Speed Profile (SSP) across depth. The acoustic signals across the VLAs can be represented in terms of orthonormal basis functions called modes. The lower modes of the basis set concentrated around mid-water propagate longer distances and can be inverted for mesoscale effects such as currents and eddies. In spite of these advantages, mode tomography has received less attention. One of the important reasons for this is that internal waves in the ocean cause significant amplitude and travel time fluctuations in the modes. The amplitude and travel time fluctuations cause errors in travel time estimates. The absence of a statistical model and the lack of signal processing techniques for internal wave effects have precluded the modes from being used in tomographic inversions. This thesis estimates a statistical model for modes affected by internal waves and then uses the estimated model to design appropriate signal processing methods to obtain tomographic observables for the low modes. In order to estimate a statistical model, this thesis uses both the LOAPEX signals and also numerical simulations. The statistical model describes the amplitude and phase coherence across different frequencies for modes at different ranges. The model suggests that Matched Subspace Detectors (MSDs) based on the amplitude statistics of the modes are the optimum detectors to make travel time estimates for modes up to 250 km. The mean of the

  15. Acoustic Signal Processing for Pipe Condition Assessment (WaterRF Report 4360)

    EPA Science Inventory

    Unique to prestressed concrete cylinder pipe (PCCP), individual wire breaks create an excitation in the pipe wall that may vary in response to the remaining compression of the pipe core. This project was designed to improve acoustic signal processing for pipe condition assessment...

  16. Acoustic emission from single point machining: Part 2, Signal changes with tool wear. Revised

    SciTech Connect

    Heiple, C.R.; Carpenter, S.H.; Armentrout, D.L.; McManigle, A.P.

    1989-12-31

    Changes in acoustic emission signal characteristics with tool wear were monitored during single point machining of 4340 steel and Ti-6Al-4V heat treated to several strength levels, 606l-T6 aluminum, 304 stainless steel, 17-4PH stainless steel, 410 stainless steel, lead, and teflon. No signal characteristic changed in the same way with tool wear for all materials tested. A single change in a particular AE signal characteristic with tool wear valid for all materials probably does not exist. Nevertheless, changes in various signal characteristic with wear for a given material may be sufficient to be used to monitor tool wear.

  17. Acoustic emission from single point machining: Part 2, Signal changes with tool wear

    SciTech Connect

    Heiple, C.R.; Carpenter, S.H.; Armentrout, D.L.; McManigle, A.P.

    1989-01-01

    Changes in acoustic emission signal characteristics with tool wear were monitored during single point machining of 4340 steel and Ti-6Al-4V heat treated to several strength levels, 606l-T6 aluminum, 304 stainless steel, 17-4PH stainless steel, 410 stainless steel, lead, and teflon. No signal characteristic changed in the same way with tool wear for all materials tested. A single change in a particular AE signal characteristic with tool wear valid for all materials probably does not exist. Nevertheless, changes in various signal characteristic with wear for a given material may be sufficient to be used to monitor tool wear.

  18. A method for reducing the level of spurious signals in surface acoustic wave filters

    NASA Astrophysics Data System (ADS)

    Borodii, Iu. N.; Grankin, I. M.; Zapunnyi, A. P.; Kolomeiko, A. V.

    1986-03-01

    A method for reducing spurious signals in surface acoustic wave (SAW) filters is proposed whereby both bulk and reflected wave signals are attenuated by electrodes of special configuration providing synphase addition of the useful signal and nonsynphase addition of spurious signal components. The electrodes of the input and output converters are made with a common focus point and equal angular apertures. The shape of the electrodes of the focusing converters on anisotropic crystal surfaces is determined by the corresponding SAW group velocity curve. An implementation of the method proposed here is examined together with some test results.

  19. Graphical Acoustic Liner Design and Analysis Tool

    NASA Technical Reports Server (NTRS)

    Howerton, Brian M. (Inventor); Jones, Michael G. (Inventor)

    2016-01-01

    An interactive liner design and impedance modeling tool comprises software utilized to design acoustic liners for use in constrained spaces, both regularly and irregularly shaped. A graphical user interface allows the acoustic channel geometry to be drawn in a liner volume while the surface impedance calculations are updated and displayed in real-time. A one-dimensional transmission line model may be used as the basis for the impedance calculations.

  20. Antifade sonar employs acoustic field diversity to recover signals from multipath fading

    SciTech Connect

    Lubman, D.

    1996-04-01

    Co-located pressure and particle motion (PM) hydrophones together with four-channel diversity combiners may be used to recover signals from multipath fading. Multipath fading is important in both shallow and deep water propagation and can be an important source of signal loss. The acoustic field diversity concept arises from the notion of conservation of signal energy and the observation that in rooms at least, the total acoustic energy density is the sum of potential energy (scalar field-sound pressure) and kinetic energy (vector field-sound PM) portions. One pressure hydrophone determines acoustic potential energy density at a point. In principle, three PM sensors (displacement, velocity, or acceleration) directed along orthogonal axes describe the kinetic energy density at a point. For a single plane wave, the time-averaged potential and kinetic field energies are identical everywhere. In multipath interference, however, potential and kinetic field energies at a point are partitioned unequally, depending mainly on relative signal phases. Thus, when pressure signals are in deep fade, abundant kinetic field signal energy may be available at that location. Performance benefits require a degree of uncorrelated fading between channels. The expectation of nearly uncorrelated fading is motivated from room theory. Performance benefits for sonar limited by independent Rayleigh fading are suggested by analogy to antifade radio. Average SNR can be improved by several decibels, holding time on target is multiplied manifold, and the bit error rate for data communication is reduced substantially. {copyright} {ital 1996 American Institute of Physics.}

  1. Antifade sonar employs acoustic field diversity to recover signals from multipath fading

    NASA Astrophysics Data System (ADS)

    Lubman, David

    1996-04-01

    Co-located pressure and particle motion (PM) hydrophones together with four-channel diversity combiners may be used to recover signals from multipath fading. Multipath fading is important in both shallow and deep water propagation and can be an important source of signal loss. The acoustic field diversity concept arises from the notion of conservation of signal energy and the observation that in rooms at least, the total acoustic energy density is the sum of potential energy (scalar field-sound pressure) and kinetic energy (vector field-sound PM) portions. One pressure hydrophone determines acoustic potential energy density at a point. In principle, three PM sensors (displacement, velocity, or acceleration) directed along orthogonal axes describe the kinetic energy density at a point. For a single plane wave, the time-averaged potential and kinetic field energies are identical everywhere. In multipath interference, however, potential and kinetic field energies at a point are partitioned unequally, depending mainly on relative signal phases. Thus, when pressure signals are in deep fade, abundant kinetic field signal energy may be available at that location. Performance benefits require a degree of uncorrelated fading between channels. The expectation of nearly uncorrelated fading is motivated from room theory. Performance benefits for sonar limited by independent Rayleigh fading are suggested by analogy to antifade radio. Average SNR can be improved by several decibels, holding time on target is multiplied manifold, and the bit error rate for data communication is reduced substantially.

  2. Acoustic emission spectral analysis of fiber composite failure mechanisms

    NASA Technical Reports Server (NTRS)

    Egan, D. M.; Williams, J. H., Jr.

    1978-01-01

    The acoustic emission of graphite fiber polyimide composite failure mechanisms was investigated with emphasis on frequency spectrum analysis. Although visual examination of spectral densities could not distinguish among fracture sources, a paired-sample t statistical analysis of mean normalized spectral densities did provide quantitative discrimination among acoustic emissions from 10 deg, 90 deg, and plus or minus 45 deg, plus or minus 45 deg sub s specimens. Comparable discrimination was not obtained for 0 deg specimens.

  3. Scaling and dimensional analysis of acoustic streaming jets

    SciTech Connect

    Moudjed, B.; Botton, V.; Henry, D.; Ben Hadid, H.

    2014-09-15

    This paper focuses on acoustic streaming free jets. This is to say that progressive acoustic waves are used to generate a steady flow far from any wall. The derivation of the governing equations under the form of a nonlinear hydrodynamics problem coupled with an acoustic propagation problem is made on the basis of a time scale discrimination approach. This approach is preferred to the usually invoked amplitude perturbations expansion since it is consistent with experimental observations of acoustic streaming flows featuring hydrodynamic nonlinearities and turbulence. Experimental results obtained with a plane transducer in water are also presented together with a review of the former experimental investigations using similar configurations. A comparison of the shape of the acoustic field with the shape of the velocity field shows that diffraction is a key ingredient in the problem though it is rarely accounted for in the literature. A scaling analysis is made and leads to two scaling laws for the typical velocity level in acoustic streaming free jets; these are both observed in our setup and in former studies by other teams. We also perform a dimensional analysis of this problem: a set of seven dimensionless groups is required to describe a typical acoustic experiment. We find that a full similarity is usually not possible between two acoustic streaming experiments featuring different fluids. We then choose to relax the similarity with respect to sound attenuation and to focus on the case of a scaled water experiment representing an acoustic streaming application in liquid metals, in particular, in liquid silicon and in liquid sodium. We show that small acoustic powers can yield relatively high Reynolds numbers and velocity levels; this could be a virtue for heat and mass transfer applications, but a drawback for ultrasonic velocimetry.

  4. Seismic and Acoustic Array Monitoring of Signal from Tungurahua Volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Terbush, B. R.; Anthony, R. E.; Johnson, J. B.; Ruiz, M. C.

    2012-12-01

    Tungurahua Volcano is an active stratovolcano located in Ecuador's eastern Cordillera. Since its most recent cycle of eruptive activity, beginning in 1999, it has produced both strombolian-to-vulcanian eruptions, and regular vapor emissions. Tungurahua is located above the city of Baños, so volcanic activity is well-monitored by Ecuador's Instituto Geofisico Nacional with a seismic and infrasound network, and other surveillance tools. Toward better understanding of the complex seismic and acoustic signals associated with low-level Tungurahua activity, and which are often low in signal-to-noise, we deployed temporary seismo-acoustic arrays between June 9th and 20th in 2012. This deployment was part of a Field Volcano Geophysics class, a collaboration between New Mexico Institute of Mining and Technology and the Escuela Politecnica Nacional's Instituto Geofísico in Ecuador. Two six-element arrays were deployed on the flank of the volcano. A seismo-acoustic array, which consisted of combined broadband seismic and infrasound sensors, possessed 100-meter spacing, and was deployed five kilometers north of the vent in an open field at 2700 m. The second array had only acoustic sensors with 30-meter spacing, and was deployed approximately six kilometers northwest of the vent, on an old pyroclastic flow deposit. The arrays picked up signals from four distinct explosion events, a number of diverse tremor signals, local volcano tectonic and long period earthquakes, and a regional tectonic event of magnitude 4.9. Coherency of both seismic and acoustic array data was quantified using Fisher Statistics, which was effective for identifying myriad signals. For most signals Fisher Statistics were particularly high in low frequency bands, between 0.5 and 2 Hz. Array analyses helped to filter out noise induced by cultural sources and livestock signals, which were particularly pronounced in the deployment site. Volcan Tungurahua sources were considered plane wave signals and could

  5. Modeling ground vehicle acoustic signatures for analysis and synthesis

    SciTech Connect

    Haschke, G.; Stanfield, R.

    1995-07-01

    Security and weapon systems use acoustic sensor signals to classify and identify moving ground vehicles. Developing robust signal processing algorithms for this is expensive, particularly in presence of acoustic clutter or countermeasures. This paper proposes a parametric ground vehicle acoustic signature model to aid the system designer in understanding which signature features are important, developing corresponding feature extraction algorithms and generating low-cost, high-fidelity synthetic signatures for testing. The authors have proposed computer-generated acoustic signatures of armored, tracked ground vehicles to deceive acoustic-sensored smart munitions. They have developed quantitative measures of how accurately a synthetic acoustic signature matches those produced by actual vehicles. This paper describes parameters of the model used to generate these synthetic signatures and suggests methods for extracting these parameters from signatures of valid vehicle encounters. The model incorporates wide-bandwidth and narrow- bandwidth components that are modulated in a pseudo-random fashion to mimic the time dynamics of valid vehicle signatures. Narrow- bandwidth feature extraction techniques estimate frequency, amplitude and phase information contained in a single set of narrow frequency- band harmonics. Wide-bandwidth feature extraction techniques estimate parameters of a correlated-noise-floor model. Finally, the authors propose a method of modeling the time dynamics of the harmonic amplitudes as a means adding necessary time-varying features to the narrow-bandwidth signal components. The authors present results of applying this modeling technique to acoustic signatures recorded during encounters with one armored, tracked vehicle. Similar modeling techniques can be applied to security systems.

  6. SIG. Signal Processing, Analysis, & Display

    SciTech Connect

    Hernandez, J.; Lager, D.; Azevedo, S.

    1992-01-22

    SIG is a general-purpose signal processing, analysis, and display program. Its main purpose is to perform manipulations on time- and frequency-domain signals. However, it has been designed to ultimately accommodate other representations for data such as multiplexed signals and complex matrices. Two user interfaces are provided in SIG - a menu mode for the unfamiliar user and a command mode for more experienced users. In both modes errors are detected as early as possible and are indicated by friendly, meaningful messages. An on-line HELP package is also included. A variety of operations can be performed on time- and frequency-domain signals including operations on the samples of a signal, operations on the entire signal, and operations on two or more signals. Signal processing operations that can be performed are digital filtering (median, Bessel, Butterworth, and Chebychev), ensemble average, resample, auto and cross spectral density, transfer function and impulse response, trend removal, convolution, Fourier transform and inverse window functions (Hamming, Kaiser-Bessel), simulation (ramp, sine, pulsetrain, random), and read/write signals. User definable signal processing algorithms are also featured. SIG has many options including multiple commands per line, command files with arguments,commenting lines, defining commands, and automatic execution for each item in a repeat sequence. Graphical operations on signals and spectra include: x-y plots of time signals; real, imaginary, magnitude, and phase plots of spectra; scaling of spectra for continuous or discrete domain; cursor zoom; families of curves; and multiple viewports.

  7. SIG. Signal Processing, Analysis, & Display

    SciTech Connect

    Hernandez, J.; Lager, D.; Azevedo, S.

    1992-01-22

    SIG is a general-purpose signal processing, analysis, and display program. Its main purpose is to perform manipulations on time and frequency-domain signals. However, it has been designed to ultimately accommodate other representations for data such as multiplexed signals and complex matrices. Two user interfaces are provided in SIG; a menu mode for the unfamiliar user and a command mode for more experienced users. In both modes errors are detected as early as possible and are indicated by friendly, meaningful messages. An on-line HELP package is also included. A variety of operations can be performed on time and frequency-domain signals including operations on the samples of a signal, operations on the entire signal, and operations on two or more signals. Signal processing operations that can be performed are digital filtering (median, Bessel, Butterworth, and Chebychev), ensemble average, resample, auto and cross spectral density, transfer function and impulse response, trend removal, convolution, Fourier transform and inverse window functions (Hamming, Kaiser-Bessel), simulation (ramp, sine, pulsetrain, random), and read/write signals. User definable signal processing algorithms are also featured. SIG has many options including multiple commands per line, command files with arguments, commenting lines, defining commands, and automatic execution for each item in a `repeat` sequence. Graphical operations on signals and spectra include: x-y plots of time signals; real, imaginary, magnitude, and phase plots of spectra; scaling of spectra for continuous or discrete domain; cursor zoom; families of curves; and multiple viewports.

  8. SIG. Signal Processing, Analysis, & Display

    SciTech Connect

    Hernandez, J.; Lager, D.; Azevedo, S.

    1992-01-22

    SIG is a general-purpose signal processing, analysis, and display program. Its main purpose is to perform manipulations on time-and frequency-domain signals. However, it has been designed to ultimately accommodate other representations for data such as multiplexed signals and complex matrices. Two user interfaces are provided in SIG - a menu mode for the unfamiliar user and a command mode for more experienced users. In both modes errors are detected as early as possible and are indicated by friendly, meaningful messages. An on-line HELP package is also included. A variety of operations can be performed on time and frequency-domain signals including operations on the samples of a signal, operations on the entire signal, and operations on two or more signals. Signal processing operations that can be performed are digital filtering (median, Bessel, Butterworth, and Chebychev), ensemble average, resample, auto and cross spectral density, transfer function and impulse response, trend removal, convolution, Fourier transform and inverse window functions (Hamming, Kaiser-Bessel), simulation (ramp, sine, pulsetrain, random), and read/write signals. User definable signal processing algorithms are also featured. SIG has many options including multiple commands per line, command files with arguments, commenting lines, defining commands, and automatic execution for each item in a repeat sequence. Graphical operations on signals and spectra include: x-y plots of time signals; real, imaginary, magnitude, and phase plots of spectra; scaling of spectra for continuous or discrete domain; cursor zoom; families of curves; and multiple viewports.

  9. Acoustic tweezers for studying intracellular calcium signaling in SKBR-3 human breast cancer cells

    PubMed Central

    Hwang, Jae Youn; Yoon, Chi Woo; Lim, Hae Gyun; Park, Jin Man; Yoon, Sangpil; Lee, Jungwoo; Shung, K. Kirk

    2016-01-01

    Extracellular matrix proteins such as fibronectin (FNT) play crucial roles in cell proliferation, adhesion, and migration. For better understanding of these associated cellular activities, various microscopic manipulation tools have been used to study their intracellular signaling pathways. Recently, it has appeared that acoustic tweezers may possess similar capabilities in the study. Therefore, we here demonstrate that our newly developed acoustic tweezers with a high-frequency lithium niobate ultrasonic transducer have potentials to study intracellular calcium signaling by FNT-binding to human breast cancer cells (SKBR-3). It is found that intracellular calcium elevations in SKBR-3 cells, initially occurring on the microbead-contacted spot and then eventually spreading over the entire cell, are elicited by attaching an acoustically trapped FNT-coated microbead. Interestingly, they are suppressed by either extracellular calcium elimination or phospholipase C (PLC) inhibition. Hence, this suggests that our acoustic tweezers may serve as an alternative tool in the study of intracellular signaling by FNT-binding activities. PMID:26150401

  10. Leak detection in gas pipeline by acoustic and signal processing - A review

    NASA Astrophysics Data System (ADS)

    Adnan, N. F.; Ghazali, M. F.; Amin, M. M.; Hamat, A. M. A.

    2015-12-01

    The pipeline system is the most important part in media transport in order to deliver fluid to another station. The weak maintenance and poor safety will contribute to financial losses in term of fluid waste and environmental impacts. There are many classifications of techniques to make it easier to show their specific method and application. This paper's discussion about gas leak detection in pipeline system using acoustic method will be presented in this paper. The wave propagation in the pipeline is a key parameter in acoustic method when the leak occurs and the pressure balance of the pipe will generated by the friction between wall in the pipe. The signal processing is used to decompose the raw signal and show in time- frequency. Findings based on the acoustic method can be used for comparative study in the future. Acoustic signal and HHT is the best method to detect leak in gas pipelines. More experiments and simulation need to be carried out to get the fast result of leaking and estimation of their location.

  11. Elevated stress hormone diminishes the strength of female preferences for acoustic signals in the green treefrog.

    PubMed

    Davis, A Gabriell; Leary, Christopher J

    2015-03-01

    Mate selection can be stressful; time spent searching for mates can increase predation risk and/or decrease food consumption, resulting in elevated stress hormone levels. Both high predation risk and low food availability are often associated with increased variation in mate choice by females, but it is not clear whether stress hormone levels contribute to such variation in female behavior. We examined how the stress hormone corticosterone (CORT) affects female preferences for acoustic signals in the green treefrog, Hyla cinerea. Specifically, we assessed whether CORT administration affects female preferences for call rate - an acoustic feature that is typically under directional selection via mate choice by females in most anurans and other species that communicate using acoustic signals. Using a dual speaker playback paradigm, we show that females that were administered higher doses of CORT were less likely to choose male advertisement calls broadcast at high rates. Neither CORT dose nor level was related to the latency of female phonotactic responses, suggesting that elevated CORT does not influence the motivation to mate. Results were also not related to circulating sex steroids (i.e., progesterone, androgens or estradiol) that have traditionally been the focus of studies examining the hormonal basis for variation in female mate choice. Our results thus indicate that elevated CORT levels decrease the strength of female preferences for acoustic signals. PMID:25644312

  12. Temperature and Pressure Dependence of Signal Amplitudes for Electrostriction Laser-Induced Thermal Acoustics

    NASA Technical Reports Server (NTRS)

    Herring, Gregory C.

    2015-01-01

    The relative signal strength of electrostriction-only (no thermal grating) laser-induced thermal acoustics (LITA) in gas-phase air is reported as a function of temperature T and pressure P. Measurements were made in the free stream of a variable Mach number supersonic wind tunnel, where T and P are varied simultaneously as Mach number is varied. Using optical heterodyning, the measured signal amplitude (related to the optical reflectivity of the acoustic grating) was averaged for each of 11 flow conditions and compared to the expected theoretical dependence of a pure-electrostriction LITA process, where the signal is proportional to the square root of [P*P /( T*T*T)].

  13. A study of the connection between tidal velocities, soliton packets and acoustic signal losses

    NASA Astrophysics Data System (ADS)

    Chin-Bing, Stanley A.; Warn-Varnas, Alex C.; King, David B.; Lamb, Kevin G.; Hawkins, James A.; Teixeira, Marvi

    2002-11-01

    Coupled ocean model and acoustic model simulations of soliton packets in the Yellow Sea have indicated that the environmental conditions necessary for anomalous signal losses can occur several times in a 24 h period. These conditions and the subsequent signal losses were observed in simulations made over an 80 h space-time evolution of soliton packets that were generated by a 0.7 m/s tidal velocity [Chin-Bing et al., J. Acoust. Soc. Am. 111, 2459 (2002)]. This particular tidal velocity was used to initiate the Lamb soliton model because the soliton packets that were generated compared favorably with SAR measurements of soliton packets in the Yellow Sea. The tidal velocities in this region can range from 0.3 m/s to 1.2 m/s. In this work we extend our simulations and analyses to include soliton packets generated by other tidal velocities in the 0.3-1.2 m/s band. Anomalous signal losses are again observed. Examples will be shown that illustrate the connections between the tidal velocities, the soliton packets that are generated by these tidal velocities, and the signal losses that can occur when acoustic signals are propagated through these soliton packets. [Work supported by ONR/NRL and by a High Performance Computing DoD grant.

  14. Numerical analysis of acoustic impedance microscope utilizing acoustic lens transducer to examine cultured cells.

    PubMed

    Gunawan, Agus Indra; Hozumi, Naohiro; Takahashi, Kenta; Yoshida, Sachiko; Saijo, Yoshifumi; Kobayashi, Kazuto; Yamamoto, Seiji

    2015-12-01

    A new technique is proposed for non-contact quantitative cell observation using focused ultrasonic waves. This technique interprets acoustic reflection intensity into the characteristic acoustic impedance of the biological cell. The cells are cultured on a plastic film substrate. A focused acoustic beam is transmitted through the substrate to its interface with the cell. A two-dimensional (2-D) reflection intensity profile is obtained by scanning the focal point along the interface. A reference substance is observed under the same conditions. These two reflections are compared and interpreted into the characteristic acoustic impedance of the cell based on a calibration curve that was created prior to the observation. To create the calibration curve, a numerical analysis of the sound field is performed using Fourier Transforms and is verified using several saline solutions. Because the cells are suspended by two plastic films, no contamination is introduced during the observation. In a practical observation, a sapphire lens transducer with a center frequency of 300 MHz was employed using ZnO thin film. The objects studied were co-cultured rat-derived glial (astrocyte) cells and glioma cells. The result was the clear observation of the internal structure of the cells. The acoustic impedance of the cells was spreading between 1.62 and 1.72 MNs/m(3). Cytoskeleton was indicated by high acoustic impedance. The introduction of cytochalasin-B led to a significant reduction in the acoustic impedance of the glioma cells; its effect on the glial cells was less significant. It is believed that this non-contact observation method will be useful for continuous cell inspections. PMID:26163739

  15. Listening to the Deep: live monitoring of ocean noise and cetacean acoustic signals.

    PubMed

    André, M; van der Schaar, M; Zaugg, S; Houégnigan, L; Sánchez, A M; Castell, J V

    2011-01-01

    The development and broad use of passive acoustic monitoring techniques have the potential to help assessing the large-scale influence of artificial noise on marine organisms and ecosystems. Deep-sea observatories have the potential to play a key role in understanding these recent acoustic changes. LIDO (Listening to the Deep Ocean Environment) is an international project that is allowing the real-time long-term monitoring of marine ambient noise as well as marine mammal sounds at cabled and standalone observatories. Here, we present the overall development of the project and the use of passive acoustic monitoring (PAM) techniques to provide the scientific community with real-time data at large spatial and temporal scales. Special attention is given to the extraction and identification of high frequency cetacean echolocation signals given the relevance of detecting target species, e.g. beaked whales, in mitigation processes, e.g. during military exercises. PMID:21665016

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  17. The acoustic simulation and analysis of complicated reciprocating compressor piping systems, I: Analysis technique and parameter matrices of acoustic elements

    NASA Astrophysics Data System (ADS)

    To, C. W. S.

    1984-09-01

    This paper describes the mathematical formulation, equations, and procedures employed in the development of a comprehensive digital computer program for acoustic simulation and analysis of large and complicated piping systems. The analysis technique used is the transfer matrix method in which the piping system, with or without multiple inputs and outputs, is represented by a combination of discrete acoustic elements interconnected to one another at two stations such that the acoustic pressure and volume velocity at one station are uniquely related to those at the other by a two-by-two parameter matrix. Parameter matrices of 19 acoustic elements are included in this paper. By making use of these parameter matrices and the analysis technique, any complicated practical reciprocating compressor piping system can be modelled or analyzed.

  18. A Spectral Analysis Approach for Acoustic Radiation from Composite Panels

    NASA Technical Reports Server (NTRS)

    Turner, Travis L.; Singh, Mahendra P.; Mei, Chuh

    2004-01-01

    A method is developed to predict the vibration response of a composite panel and the resulting far-field acoustic radiation due to acoustic excitation. The acoustic excitation is assumed to consist of obliquely incident plane waves. The panel is modeled by a finite element analysis and the radiated field is predicted using Rayleigh's integral. The approach can easily include other effects such as shape memory alloy (SMA) ber reinforcement, large detection thermal postbuckling, and non-symmetric SMA distribution or lamination. Transmission loss predictions for the case of an aluminum panel excited by a harmonic acoustic pressure are shown to compare very well with a classical analysis. Results for a composite panel with and without shape memory alloy reinforcement are also presented. The preliminary results demonstrate that the transmission loss can be significantly increased with shape memory alloy reinforcement. The mechanisms for further transmission loss improvement are identified and discussed.

  19. Bearing defect signature analysis using advanced nonlinear signal analysis in a controlled environment

    NASA Technical Reports Server (NTRS)

    Zoladz, T.; Earhart, E.; Fiorucci, T.

    1995-01-01

    Utilizing high-frequency data from a highly instrumented rotor assembly, seeded bearing defect signatures are characterized using both conventional linear approaches, such as power spectral density analysis, and recently developed nonlinear techniques such as bicoherence analysis. Traditional low-frequency (less than 20 kHz) analysis and high-frequency envelope analysis of both accelerometer and acoustic emission data are used to recover characteristic bearing distress information buried deeply in acquired data. The successful coupling of newly developed nonlinear signal analysis with recovered wideband envelope data from accelerometers and acoustic emission sensors is the innovative focus of this research.

  20. Acoustics

    NASA Astrophysics Data System (ADS)

    The acoustics research activities of the DLR fluid-mechanics department (Forschungsbereich Stroemungsmechanik) during 1988 are surveyed and illustrated with extensive diagrams, drawings, graphs, and photographs. Particular attention is given to studies of helicopter rotor noise (high-speed impulsive noise, blade/vortex interaction noise, and main/tail-rotor interaction noise), propeller noise (temperature, angle-of-attack, and nonuniform-flow effects), noise certification, and industrial acoustics (road-vehicle flow noise and airport noise-control installations).

  1. Analysis of some acoustics-jet flow interaction problems

    NASA Technical Reports Server (NTRS)

    Chow, P. L.

    1984-01-01

    Analytical problems in the interactions between the mean-shear flows and the acoustic field in the planar and circular jets are examined. These problems are basic in understanding the effects of coherent large structure on the generation and complications of sound in a sub-sonic jet. Three problems were investigated: (1) spatial (vs. temporal) normal mode analysis in a planar jets; (2) a slightly divergent, planar jet; and (3) acoustic waves in an axisymmetrical jet.

  2. Acoustic emission intensity analysis of corrosion in prestressed concrete piles

    NASA Astrophysics Data System (ADS)

    Vélez, William; Matta, Fabio; Ziehl, Paul

    2014-02-01

    Corrosion of steel strands in prestressed concrete (PC) bridges may lead to substantial damage or collapse well before the end of the design life. Acoustic Emission (AE) is a suitable nondestructive technique to detect and locate corrosion in reinforced and prestressed concrete, which is key to prioritize inspection and maintenance. An effective tool to analyze damage-related AE data is intensity analysis (IA), which is based on two data trends, namely Severity (average signal strength of high amplitude hits) and Historic Index (ratio of the average signal strength of the most recent hits to the average of all hits). IA criteria for corrosion assessment in PC were recently proposed based on empirical evidence from accelerated corrosion tests. In this paper, AE data from prestressed and non-prestressed concrete pile specimens exposed to salt water wet-dry cycling for over 600 days are used to analyze the relation between Severity and Historic Index and actual corrosion. Evidence of corrosion is gained from the inspection of decommissioned specimens. The selection of suitable J and K parameters for IA is discussed, and an IA chart with updated corrosion criteria for PC piles is presented.

  3. In situ high temperature oxidation analysis of Zircaloy-4 using acoustic emission coupled with thermogravimetry

    NASA Astrophysics Data System (ADS)

    Omar, Al Haj; Véronique, Peres; Eric, Serris; François, Grosjean; Jean, Kittel; François, Ropital; Michel, Cournil

    2015-06-01

    Zircaloy-4 oxidation behavior at high temperature (900 °C), which can be reached in case of severe accidental situations in nuclear pressurised water reactor, was studied using acoustic emission analysis coupled with thermogravimetry. Two different atmospheres were used to study the oxidation of Zircaloy-4: (a) helium and pure oxygen, (b) helium and oxygen combined with slight addition of air. The experiments with 20% of oxygen confirm the dependence on oxygen anions diffusion in the oxide scale. Under a mixture of oxygen and air in helium, an acceleration of the corrosion was observed due to the detrimental effect of nitrogen. The kinetic rate increased significantly after a kinetic transition (breakaway). This acceleration was accompanied by an acoustic emission activity. Most of the acoustic emission bursts were recorded after the kinetic transition (post-transition) or during the cooling of the sample. The characteristic features of the acoustic emission signals appear to be correlated with the different populations of cracks and their occurrence in the ZrO2 layer or in the α-Zr(O) layer. Acoustic events were recorded during the isothermal dwell time at high temperature under air. They were associated with large cracks in the zirconia porous layer. Acoustic events were also recorded during cooling after oxidation tests both under air or oxygen. For the latter, cracks were observed in the oxygen enriched zirconium metal phase and not in the dense zirconia layer after 5 h of oxidation.

  4. LES and acoustic analysis of thermo-acoustic instabilities in a partially premixed model combustor

    NASA Astrophysics Data System (ADS)

    Hernández, Ignacio; Staffelbach, Gabriel; Poinsot, Thierry; Román Casado, Juan C.; Kok, Jim B. W.

    2013-01-01

    Numerical simulations were performed using Large Eddy Simulation (LES) and acoustic analysis tools to study thermo-acoustic instabilities in a methane/air academic burner installed at the University of Twente (The Netherlands). It operates under fuel-lean partially premixed conditions at atmospheric pressure, and was built to study thermo-acoustic instabilities in conditions representative of gas turbine Lean Premixed systems: gaseous fuel is injected upstream of the combustor and has a limited time to mix with air. Even though the objective is to burn in a premixed mode, the actual regime corresponds to a partially premixed flame where strong equivalence ratio variations are created especially during combustion instabilities. Capturing these modes with LES is a challenge: here, simulations for both stable and unstable regimes are performed. In the unstable case, the limit cycle oscillations (LCO) are characterized and compared to experimental results. Reasonable agreement is found between simulations and experiments.

  5. A comparative study of the svm and k-nn machine learning algorithms for the diagnosis of respiratory pathologies using pulmonary acoustic signals

    PubMed Central

    2014-01-01

    Background Pulmonary acoustic parameters extracted from recorded respiratory sounds provide valuable information for the detection of respiratory pathologies. The automated analysis of pulmonary acoustic signals can serve as a differential diagnosis tool for medical professionals, a learning tool for medical students, and a self-management tool for patients. In this context, we intend to evaluate and compare the performance of the support vector machine (SVM) and K-nearest neighbour (K-nn) classifiers in diagnosis respiratory pathologies using respiratory sounds from R.A.L.E database. Results The pulmonary acoustic signals used in this study were obtained from the R.A.L.E lung sound database. The pulmonary acoustic signals were manually categorised into three different groups, namely normal, airway obstruction pathology, and parenchymal pathology. The mel-frequency cepstral coefficient (MFCC) features were extracted from the pre-processed pulmonary acoustic signals. The MFCC features were analysed by one-way ANOVA and then fed separately into the SVM and K-nn classifiers. The performances of the classifiers were analysed using the confusion matrix technique. The statistical analysis of the MFCC features using one-way ANOVA showed that the extracted MFCC features are significantly different (p < 0.001). The classification accuracies of the SVM and K-nn classifiers were found to be 92.19% and 98.26%, respectively. Conclusion Although the data used to train and test the classifiers are limited, the classification accuracies found are satisfactory. The K-nn classifier was better than the SVM classifier for the discrimination of pulmonary acoustic signals from pathological and normal subjects obtained from the RALE database. PMID:24970564

  6. Signal characteristics of an underwater explosive acoustic telemetry system

    SciTech Connect

    Calloway, T.M.

    1984-07-01

    Pressure pulses from small (<1 gm) explosive charges detonated between depths of 150 and 1200 m and detected by hydrophones submerged at a depth of 45 m are analyzed. Experimental data on peak pressures, time constants, and shock-wave/bubble-pulse intervals are summarized. The mass of each explosive is converted to its TNT energy-equivalent mass, which is used in fitting semiempirical scaling laws to the data. Equations are obtained for predicting the characteristics of the signal, given the range and depth of the explosive together with its TNT energy-equivalent mass. The parameter values that provide the best fit of the scaling laws to the experimental data are compared with those values applicable to larger explosives (>50 gm) detonated within 150 m of the surface. 20 references, 7 figures, 8 tables.

  7. Near- Source, Seismo-Acoustic Signals Accompanying a NASCAR Race at the Texas Motor Speedway

    NASA Astrophysics Data System (ADS)

    Stump, B. W.; Hayward, C.; Underwood, R.; Howard, J. E.; MacPhail, M. D.; Golden, P.; Endress, A.

    2014-12-01

    Near-source, seismo-acoustic observations provide a unique opportunity to characterize urban sources, remotely sense human activities including vehicular traffic and monitor large engineering structures. Energy separately coupled into the solid earth and atmosphere provides constraints on not only the location of these sources but also the physics of the generating process. Conditions and distances at which these observations can be made are dependent upon not only local geological conditions but also atmospheric conditions at the time of the observations. In order to address this range of topics, an empirical, seismo-acoustic study was undertaken in and around the Texas Motor Speedway in the Dallas-Ft. Worth area during the first week of April 2014 at which time a range of activities associated with a series of NASCAR races occurred. Nine, seismic sensors were deployed around the 1.5-mile track for purposes of documenting the direct-coupled seismic energy from the passage of the cars and other vehicles on the track. Six infrasound sensors were deployed on a rooftop in a rectangular array configuration designed to provide high frequency beam forming for acoustic signals. Finally, a five-element infrasound array was deployed outside the track in order to characterize how the signals propagate away from the sources in the near-source region. Signals recovered from within the track were able to track and characterize the motion of a variety of vehicles during the race weekend including individual racecars. Seismic data sampled at 1000 sps documented strong Doppler effects as the cars approached and moved away from individual sensors. There were faint seismic signals that arrived at seismic velocity but local acoustic to seismic coupling as supported by the acoustic observations generated the majority of seismic signals. Actual seismic ground motions were small as demonstrated by the dominance of regional seismic signals from a magnitude 4.0 earthquake that arrived at

  8. Seismo-acoustic signals associated with degassing explosions recorded at Shishaldin Volcano, Alaska, 2003 2004

    NASA Astrophysics Data System (ADS)

    Petersen, Tanja; McNutt, Stephen R.

    2007-03-01

    In summer 2003, a Chaparral Model 2 microphone was deployed at Shishaldin Volcano, Aleutian Islands, Alaska. The pressure sensor was co-located with a short-period seismometer on the volcano’s north flank at a distance of 6.62 km from the active summit vent. The seismo-acoustic data exhibit a correlation between impulsive acoustic signals (1 2 Pa) and long-period (LP, 1 2 Hz) earthquakes. Since it last erupted in 1999, Shishaldin has been characterized by sustained seismicity consisting of many hundreds to two thousand LP events per day. The activity is accompanied by up to ˜200 m high discrete gas puffs exiting the small summit vent, but no significant eruptive activity has been confirmed. The acoustic waveforms possess similarity throughout the data set (July 2003 November 2004) indicating a repetitive source mechanism. The simplicity of the acoustic waveforms, the impulsive onsets with relatively short (˜10 20 s) gradually decaying codas and the waveform similarities suggest that the acoustic pulses are generated at the fluid air interface within an open-vent system. SO2 measurements have revealed a low SO2 flux, suggesting a hydrothermal system with magmatic gases leaking through. This hypothesis is supported by the steady-state nature of Shishaldin’s volcanic system since 1999. Time delays between the seismic LP and infrasound onsets were acquired from a representative day of seismo-acoustic data. A simple model was used to estimate source depths. The short seismo-acoustic delay times have revealed that the seismic and acoustic sources are co-located at a depth of 240±200 m below the crater rim. This shallow depth is confirmed by resonance of the upper portion of the open conduit, which produces standing waves with f=0.3 Hz in the acoustic waveform codas. The infrasound data has allowed us to relate Shishaldin’s LP earthquakes to degassing explosions, created by gas volume ruptures from a fluid air interface.

  9. Problems Associated with Statistical Pattern Recognition of Acoustic Emission Signals in a Compact Tension Fatigue Specimen

    NASA Technical Reports Server (NTRS)

    Hinton, Yolanda L.

    1999-01-01

    Acoustic emission (AE) data were acquired during fatigue testing of an aluminum 2024-T4 compact tension specimen using a commercially available AE system. AE signals from crack extension were identified and separated from noise spikes, signals that reflected from the specimen edges, and signals that saturated the instrumentation. A commercially available software package was used to train a statistical pattern recognition system to classify the signals. The software trained a network to recognize signals with a 91-percent accuracy when compared with the researcher's interpretation of the data. Reasons for the discrepancies are examined and it is postulated that additional preprocessing of the AE data to focus on the extensional wave mode and eliminate other effects before training the pattern recognition system will result in increased accuracy.

  10. Non-invasive estimation of static and pulsatile intracranial pressure from transcranial acoustic signals.

    PubMed

    Levinsky, Alexandra; Papyan, Surik; Weinberg, Guy; Stadheim, Trond; Eide, Per Kristian

    2016-05-01

    The aim of the present study was to examine whether a method for estimation of non-invasive ICP (nICP) from transcranial acoustic (TCA) signals mixed with head-generated sounds estimate the static and pulsatile invasive ICP (iICP). For that purpose, simultaneous iICP and mixed TCA signals were obtained from patients undergoing continuous iICP monitoring as part of clinical management. The ear probe placed in the right outer ear channel sent a TCA signal with fixed frequency (621 Hz) that was picked up by the left ear probe along with acoustic signals generated by the intracranial compartment. Based on a mathematical model of the association between mixed TCA and iICP, the static and pulsatile nICP values were determined. Total 39 patients were included in the study; the total number of observations for prediction of static and pulsatile iICP were 5789 and 6791, respectively. The results demonstrated a good agreement between iICP/nICP observations, with mean difference of 0.39 mmHg and 0.53 mmHg for static and pulsatile ICP, respectively. In summary, in this cohort of patients, mixed TCA signals estimated the static and pulsatile iICP with rather good accuracy. Further studies are required to validate whether mixed TCA signals may become useful for measurement of nICP. PMID:26997563

  11. Dual fiber Bragg gratings configuration-based fiber acoustic sensor for low-frequency signal detection

    NASA Astrophysics Data System (ADS)

    Yang, Dong; Wang, Shun; Lu, Ping; Liu, Deming

    2014-11-01

    We propose and fabricate a new type fiber acoustic sensor based on dual fiber Bragg gratings (FBGs) configuration. The acoustic sensor head is constructed by putting the sensing cells enclosed in an aluminum cylinder space built by two Cband FBGs and a titanium diaphragm of 50 um thickness. One end of each FBG is longitudinally adhered to the diaphragm by UV glue. Both of the two FBGs are employed for reflecting light. The dual FBGs play roles not only as signal transmission system but also as sensing component, and they demodulate each other's optical signal mutually during the measurement. Both of the two FBGs are pre-strained and the output optical power experiences fluctuation in a linear relationship along with a variation of axial strain and surrounding acoustic interference. So a precise approach to measure the frequency and sound pressure of the acoustic disturbance is achieved. Experiments are performed and results show that a relatively flat frequency response in a range from 200 Hz to 1 kHz with the average signal-to-noise ratio (SNR) above 21 dB is obtained. The maximum sound pressure sensitivity of 11.35mV/Pa is achieved with the Rsquared value of 0.99131 when the sound pressure in the range of 87.7-106.6dB. It has potential applications in low frequency signal detection. Owing to its direct self-demodulation method, the sensing system reveals the advantages of easy to demodulate, good temperature stability and measurement reliability. Besides, performance of the proposed sensor could be improved by optimizing the parameters of the sensor, especially the diaphragm.

  12. Circuit for echo and noise suppression of acoustic signals transmitted through a drill string

    DOEpatents

    Drumheller, D.S.; Scott, D.D.

    1993-12-28

    An electronic circuit for digitally processing analog electrical signals produced by at least one acoustic transducer is presented. In a preferred embodiment of the present invention, a novel digital time delay circuit is utilized which employs an array of First-in-First-out (FiFo) microchips. Also, a bandpass filter is used at the input to this circuit for isolating drill string noise and eliminating high frequency output. 20 figures.

  13. Gearbox fault diagnosis based on deep random forest fusion of acoustic and vibratory signals

    NASA Astrophysics Data System (ADS)

    Li, Chuan; Sanchez, René-Vinicio; Zurita, Grover; Cerrada, Mariela; Cabrera, Diego; Vásquez, Rafael E.

    2016-08-01

    Fault diagnosis is an effective tool to guarantee safe operations in gearboxes. Acoustic and vibratory measurements in such mechanical devices are all sensitive to the existence of faults. This work addresses the use of a deep random forest fusion (DRFF) technique to improve fault diagnosis performance for gearboxes by using measurements of an acoustic emission (AE) sensor and an accelerometer that are used for monitoring the gearbox condition simultaneously. The statistical parameters of the wavelet packet transform (WPT) are first produced from the AE signal and the vibratory signal, respectively. Two deep Boltzmann machines (DBMs) are then developed for deep representations of the WPT statistical parameters. A random forest is finally suggested to fuse the outputs of the two DBMs as the integrated DRFF model. The proposed DRFF technique is evaluated using gearbox fault diagnosis experiments under different operational conditions, and achieves 97.68% of the classification rate for 11 different condition patterns. Compared to other peer algorithms, the addressed method exhibits the best performance. The results indicate that the deep learning fusion of acoustic and vibratory signals may improve fault diagnosis capabilities for gearboxes.

  14. Assessment of infant cry: acoustic cry analysis and parental perception.

    PubMed

    LaGasse, Linda L; Neal, A Rebecca; Lester, Barry M

    2005-01-01

    Infant crying signals distress to potential caretakers who can alleviate the aversive conditions that gave rise to the cry. The cry signal results from coordination among several brain regions that control respiration and vocal cord vibration from which the cry sounds are produced. Previous work has shown a relationship between acoustic characteristics of the cry and diagnoses related to neurological damage, SIDS, prematurity, medical conditions, and substance exposure during pregnancy. Thus, assessment of infant cry provides a window into the neurological and medical status of the infant. Assessment of infant cry is brief and noninvasive and requires recording equipment and a standardized stimulus to elicit a pain cry. The typical protocol involves 30 seconds of crying from a single application of the stimulus. The recorded cry is submitted to an automated computer analysis system that digitizes the cry and either presents a digital spectrogram of the cry or calculates measures of cry characteristics. The most common interpretation of cry measures is based on deviations from typical cry characteristics. Another approach evaluates the pattern across cry characteristics suggesting arousal or under-arousal or difficult temperament. Infants with abnormal cries should be referred for a full neurological evaluation. The second function of crying--to elicit caretaking--involves parent perception of the infant's needs. Typically, parents are sensitive to deviations in cry characteristics, but their perception can be altered by factors in themselves (e.g., depression) or in the context (e.g., culture). The potential for cry assessment is largely untapped. Infant crying and parental response is the first language of the new dyadic relationship. Deviations in the signal and/or misunderstanding the message can compromise infant care, parental effectiveness, and undermine the budding relationship. (c) 2005 Wiley-Liss, Inc. MRDD Research Reviews 2005;11:83-93. PMID:15856439

  15. Acoustic Analysis of Plutonium and Nuclear Weapon Components at Los Alamos National Laboratory

    NASA Astrophysics Data System (ADS)

    Saleh, T. A.; Reynolds, J. J.; Rowe, C. A.; Freibert, F. J.; Ten Cate, J. A.; Ulrich, T. J.; Farrow, A. M.

    2012-12-01

    One of the primary missions of Los Alamos National Laboratory is to use science based techniques to certify the nuclear weapons stockpile of the United States. As such we use numerous NDE techniques to monitor materials and systems properties in weapons. Two techniques will be discussed in this presentation, Acoustic Resonance Spectroscopy (ARS) and Acoustic Emission (AE). ARS is used to observe manufacturing variations or changes in the plutonium containing component (pit) of the weapon system. Both quantitative and qualitative comparisons can be used to determine variation in the pit components. Piezoelectric transducer driven acoustic resonance experiments will be described along with initial qualitative and more complex analysis and comparison techniques derived from earthquake analysis performed at LANL. Similarly, AE is used to measure the time of arrival of acoustic signals created by mechanical events that can occur in nuclear weapon components. Both traditional time of arrival techniques and more advanced techniques are used to pinpoint the location and type of acoustic emission event. Similar experiments on tensile tests of brittle phases of plutonium metal will be described.

  16. Phase Time and Envelope Time in Time-Distance Analysis and Acoustic Imaging

    NASA Technical Reports Server (NTRS)

    Chou, Dean-Yi; Duvall, Thomas L.; Sun, Ming-Tsung; Chang, Hsiang-Kuang; Jimenez, Antonio; Rabello-Soares, Maria Cristina; Ai, Guoxiang; Wang, Gwo-Ping; Goode Philip; Marquette, William; Ehgamberdiev, Shuhrat; Landenkov, Oleg

    1999-01-01

    Time-distance analysis and acoustic imaging are two related techniques to probe the local properties of solar interior. In this study, we discuss the relation of phase time and envelope time between the two techniques. The location of the envelope peak of the cross correlation function in time-distance analysis is identified as the travel time of the wave packet formed by modes with the same w/l. The phase time of the cross correlation function provides information of the phase change accumulated along the wave path, including the phase change at the boundaries of the mode cavity. The acoustic signals constructed with the technique of acoustic imaging contain both phase and intensity information. The phase of constructed signals can be studied by computing the cross correlation function between time series constructed with ingoing and outgoing waves. In this study, we use the data taken with the Taiwan Oscillation Network (TON) instrument and the Michelson Doppler Imager (MDI) instrument. The analysis is carried out for the quiet Sun. We use the relation of envelope time versus distance measured in time-distance analyses to construct the acoustic signals in acoustic imaging analyses. The phase time of the cross correlation function of constructed ingoing and outgoing time series is twice the difference between the phase time and envelope time in time-distance analyses as predicted. The envelope peak of the cross correlation function between constructed ingoing and outgoing time series is located at zero time as predicted for results of one-bounce at 3 mHz for all four data sets and two-bounce at 3 mHz for two TON data sets. But it is different from zero for other cases. The cause of the deviation of the envelope peak from zero is not known.

  17. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

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

  18. Acoustic Source Bearing Estimation (ASBE) computer program development

    NASA Technical Reports Server (NTRS)

    Wiese, Michael R.

    1987-01-01

    A new bearing estimation algorithm (Acoustic Source Analysis Technique - ASAT) and an acoustic analysis computer program (Acoustic Source Bearing Estimation - ASBE) are described, which were developed by Computer Sciences Corporation for NASA Langley Research Center. The ASBE program is used by the Acoustics Division/Applied Acoustics Branch and the Instrument Research Division/Electro-Mechanical Instrumentation Branch to analyze acoustic data and estimate the azimuths from which the source signals radiated. Included are the input and output from a benchmark test case.

  19. Behavioral assessment of acoustic parameters relevant to signal recognition and preference in a vocal fish.

    PubMed

    McKibben, J R; Bass, A H

    1998-12-01

    Acoustic signal recognition depends on the receiver's processing of the physical attributes of a sound. This study takes advantage of the simple communication sounds produced by plainfin midshipman fish to examine effects of signal variation on call recognition and preference. Nesting male midshipman generate both long duration (> 1 min) sinusoidal-like "hums" and short duration "grunts." The hums of neighboring males often overlap, creating beat waveforms. Presentation of humlike, single tone stimuli, but not grunts or noise, elicited robust attraction (phonotaxis) by gravid females. In two-choice tests, females differentiated and chose between acoustic signals that differed in duration, frequency, amplitude, and fine temporal content. Frequency preferences were temperature dependent, in accord with the known temperature dependence of hum fundamental frequency. Concurrent hums were simulated with two-tone beat stimuli, either presented from a single speaker or produced more naturally by interference between adjacent sources. Whereas certain single-source beats reduced stimulus attractiveness, beats which resolved into unmodulated tones at their sources did not affect preference. These results demonstrate that phonotactic assessment of stimulus relevance can be applied in a teleost fish, and that multiple signal parameters can affect receiver response in a vertebrate with relatively simple communication signals. PMID:9857511

  20. The correlation dimension: A robust chaotic feature for classifying acoustic emission signals generated in construction materials

    NASA Astrophysics Data System (ADS)

    Kacimi, S.; Laurens, S.

    2009-07-01

    In the field of acoustic emission (AE) source recognition, this paper presents a classification feature based on the paradigm of nonlinear dynamical systems, often referred to as chaos theory. The approach considers signals as time series expressing an underlying dynamical phenomenon and enclosing all the information regarding the dynamics. The scientific knowledge on nonlinear dynamical systems has considerably improved for the past 40 years. The dynamical behavior is analyzed in the phase space, which is the space generated by the state variables of the system. The time evolution of a system is expressed in the phase space by trajectories, and the asymptotic behavior of trajectories defines a space area which is referred to as a system attractor. Dynamical systems may be characterized by the topological properties of attractors, such as the correlation dimension, which is a fractal dimension. According to Takens theorem, even if the system is not clearly defined, it is possible to infer topological information about the attractor from experimental observations. Such a method, which is called phase space reconstruction, was successfully applied for the classification of acoustic emission waveforms propagating in more or less complex materials such as granite and concrete. Laboratory tests were carried out in order to collect numerous AE waveforms from various controlled acoustic sources. Then, each signal was processed to extract a reconstructed attractor from which the correlation dimension was computed. The first results of this research show that the correlation dimension assessed after phase space reconstruction is very relevant and robust for classifying AE signals. These promising results may be explained by the fact that the totality of the signal is used to achieve classifying information. Moreover, due to the self-similar nature of attractors, the correlation dimension, and thus a correlation dimension-based classification approach, is theoretically

  1. Acoustic alarm signalling facilitates predator protection of treehoppers by mutualist ant bodyguards

    PubMed Central

    Morales, Manuel A; Barone, Jennifer L; Henry, Charles S

    2008-01-01

    Mutualism is a net positive interaction that includes varying degrees of both costs and benefits. Because tension between the costs and benefits of mutualism can lead to evolutionary instability, identifying mechanisms that regulate investment between partners is critical to understanding the evolution and maintenance of mutualism. Recently, studies have highlighted the importance of interspecific signalling as one mechanism for regulating investment between mutualist partners. Here, we provide evidence for interspecific alarm signalling in an insect protection mutualism and we demonstrate a functional link between this acoustic signalling and efficacy of protection. The treehopper Publilia concava Say (Hemiptera: Membracidae) is an insect that provides ants with a carbohydrate-rich excretion called honeydew in return for protection from predators. Adults of this species produce distinct vibrational signals in the context of predator encounters. In laboratory trials, putative alarm signal production significantly increased following initial contact with ladybeetle predators (primarily Harmonia axyridis Pallas, Coleoptera: Coccinellidae), but not following initial contact with ants. In field trials, playback of a recorded treehopper alarm signal resulted in a significant increase in both ant activity and the probability of ladybeetle discovery by ants relative to both silence and treehopper courtship signal controls. Our results show that P. concava treehoppers produce alarm signals in response to predator threat and that this signalling can increase effectiveness of predator protection by ants. PMID:18480015

  2. Minimizing vehicle noise and weight using panel acoustic contribution analysis

    NASA Astrophysics Data System (ADS)

    Brown, Gordon M.

    1998-05-01

    Panel acoustic contribution analysis (PACA) is an advanced engineering tool to improve noise, vibration, and harshness quality and minimize weight of vehicles. It is a technique to categorize areas of vehicle body panels as positive (sound level increases as vibration amplitude increases), negative or neutral according to their contribution to the total sound. PACA is a hybrid of computer aided engineering and experimental methods. Computer aided holometry, scanning laser velocimetry, or an accelerometer net is used to experimentally measure structure vibration complex velocities. These velocities are the boundary conditions for a boundary element model of the acoustic cavity. Boundary element analysis is then used to predict the vehicle interior sound and calculate panel acoustic contributions. Experimental results for a welded steel box (validation) and vehicle application are presented.

  3. Nested sampling applied in Bayesian room-acoustics decay analysis.

    PubMed

    Jasa, Tomislav; Xiang, Ning

    2012-11-01

    Room-acoustic energy decays often exhibit single-rate or multiple-rate characteristics in a wide variety of rooms/halls. Both the energy decay order and decay parameter estimation are of practical significance in architectural acoustics applications, representing two different levels of Bayesian probabilistic inference. This paper discusses a model-based sound energy decay analysis within a Bayesian framework utilizing the nested sampling algorithm. The nested sampling algorithm is specifically developed to evaluate the Bayesian evidence required for determining the energy decay order with decay parameter estimates as a secondary result. Taking the energy decay analysis in architectural acoustics as an example, this paper demonstrates that two different levels of inference, decay model-selection and decay parameter estimation, can be cohesively accomplished by the nested sampling algorithm. PMID:23145609

  4. Discussion about generation mechanisms of third-order nonlinear signals in surface acoustic wave resonators based on simulation

    NASA Astrophysics Data System (ADS)

    Nakagawa, Ryo; Suzuki, Takanao; Shimizu, Hiroshi; Kyoya, Haruki; Nako, Katsuhiro; Hashimoto, Ken-ya

    2016-07-01

    In this paper, we discuss the generation mechanisms of third-order nonlinearity in surface acoustic wave (SAW) devices on the basis of simulation results, which are obtained by a proposed method for this discussion. First, eight nonlinear terms are introduced to the piezoelectric constitutive equations, and nonlinear stress and electric flux fields are estimated using linear strain and electric fields calculated by a linear analysis, i.e., the coupling of mode simulation. Then, their contributions are embedded as voltage and current sources, respectively, in an equivalent circuit model, and nonlinear signals appearing at external ports are estimated. It is shown that eight coefficients of the nonlinear terms can be determined from a series of experiments carried out at various driving and resulting frequencies. This is because the effect of each nonlinear term on the nonlinear signal outputs changes markedly with the conditions. When the coefficients are determined properly, the simulations agree well with some measurement results under various conditions.

  5. Temporal patterns in the acoustic signals of beaked whales at Cross Seamount.

    PubMed

    Johnston, D W; McDonald, M; Polovina, J; Domokos, R; Wiggins, S; Hildebrand, J

    2008-04-23

    Seamounts may influence the distribution of marine mammals through a combination of increased ocean mixing, enhanced local productivity and greater prey availability. To study the effects of seamounts on the presence and acoustic behaviour of cetaceans, we deployed a high-frequency acoustic recording package on the summit of Cross Seamount during April through October 2005. The most frequently detected cetacean vocalizations were echolocation sounds similar to those produced by ziphiid and mesoplodont beaked whales together with buzz-type signals consistent with prey-capture attempts. Beaked whale signals occurred almost entirely at night throughout the six-month deployment. Measurements of prey presence with a Simrad EK-60 fisheries acoustics echo sounder indicate that Cross Seamount may enhance local productivity in near-surface waters. Concentrations of micronekton were aggregated over the seamount in near-surface waters at night, and dense concentrations of nekton were detected across the surface of the summit. Our results suggest that seamounts may provide enhanced foraging opportunities for beaked whales during the night through a combination of increased productivity, vertical migrations by micronekton and local retention of prey. Furthermore, the summit of the seamount may act as a barrier against which whales concentrate prey. PMID:18252660

  6. Extruded Bread Classification on the Basis of Acoustic Emission Signal With Application of Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Świetlicka, Izabela; Muszyński, Siemowit; Marzec, Agata

    2015-04-01

    The presented work covers the problem of developing a method of extruded bread classification with the application of artificial neural networks. Extruded flat graham, corn, and rye breads differening in water activity were used. The breads were subjected to the compression test with simultaneous registration of acoustic signal. The amplitude-time records were analyzed both in time and frequency domains. Acoustic emission signal parameters: single energy, counts, amplitude, and duration acoustic emission were determined for the breads in four water activities: initial (0.362 for rye, 0.377 for corn, and 0.371 for graham bread), 0.432, 0.529, and 0.648. For classification and the clustering process, radial basis function, and self-organizing maps (Kohonen network) were used. Artificial neural networks were examined with respect to their ability to classify or to cluster samples according to the bread type, water activity value, and both of them. The best examination results were achieved by the radial basis function network in classification according to water activity (88%), while the self-organizing maps network yielded 81% during bread type clustering.

  7. Incident signal power comparison for localization of concurrent multiple acoustic sources.

    PubMed

    Salvati, Daniele; Canazza, Sergio

    2014-01-01

    In this paper, a method to solve the localization of concurrent multiple acoustic sources in large open spaces is presented. The problem of the multisource localization in far-field conditions is to correctly associate the direction of arrival (DOA) estimated by a network array system to the same source. The use of systems implementing a Bayesian filter is a traditional approach to address the problem of localization in multisource acoustic scenario. However, in a real noisy open space the acoustic sources are often discontinuous with numerous short-duration events and thus the filtering methods may have difficulty to track the multiple sources. Incident signal power comparison (ISPC) is proposed to compute DOAs association. ISPC is based on identifying the incident signal power (ISP) of the sources on a microphone array using beamforming methods and comparing the ISP between different arrays using spectral distance (SD) measurement techniques. This method solves the ambiguities, due to the presence of simultaneous sources, by identifying sounds through a minimization of an error criterion on SD measures of DOA combinations. The experimental results were conducted in an outdoor real noisy environment and the ISPC performance is reported using different beamforming techniques and SD functions. PMID:24701179

  8. Incident Signal Power Comparison for Localization of Concurrent Multiple Acoustic Sources

    PubMed Central

    2014-01-01

    In this paper, a method to solve the localization of concurrent multiple acoustic sources in large open spaces is presented. The problem of the multisource localization in far-field conditions is to correctly associate the direction of arrival (DOA) estimated by a network array system to the same source. The use of systems implementing a Bayesian filter is a traditional approach to address the problem of localization in multisource acoustic scenario. However, in a real noisy open space the acoustic sources are often discontinuous with numerous short-duration events and thus the filtering methods may have difficulty to track the multiple sources. Incident signal power comparison (ISPC) is proposed to compute DOAs association. ISPC is based on identifying the incident signal power (ISP) of the sources on a microphone array using beamforming methods and comparing the ISP between different arrays using spectral distance (SD) measurement techniques. This method solves the ambiguities, due to the presence of simultaneous sources, by identifying sounds through a minimization of an error criterion on SD measures of DOA combinations. The experimental results were conducted in an outdoor real noisy environment and the ISPC performance is reported using different beamforming techniques and SD functions. PMID:24701179

  9. Acoustic analysis in Mudejar-Gothic churches: experimental results.

    PubMed

    Galindo, Miguel; Zamarreño, Teófilo; Girón, Sara

    2005-05-01

    This paper describes the preliminary results of research work in acoustics, conducted in a set of 12 Mudejar-Gothic churches in the city of Seville in the south of Spain. Despite common architectural style, the churches feature individual characteristics and have volumes ranging from 3947 to 10 708 m3. Acoustic parameters were measured in unoccupied churches according to the ISO-3382 standard. An extensive experimental study was carried out using impulse response analysis through a maximum length sequence measurement system in each church. It covered aspects such as reverberation (reverberation times, early decay times), distribution of sound levels (sound strength); early to late sound energy parameters derived from the impulse responses (center time, clarity for speech, clarity, definition, lateral energy fraction), and speech intelligibility (rapid speech transmission index), which all take both spectral and spatial distribution into account. Background noise was also measured to obtain the NR indices. The study describes the acoustic field inside each temple and establishes a discussion for each one of the acoustic descriptors mentioned by using the theoretical models available and the principles of architectural acoustics. Analysis of the quality of the spaces for music and speech is carried out according to the most widespread criteria for auditoria. PMID:15957758

  10. Acoustic analysis in Mudejar-Gothic churches: Experimental results

    NASA Astrophysics Data System (ADS)

    Galindo, Miguel; Zamarreño, Teófilo; Girón, Sara

    2005-05-01

    This paper describes the preliminary results of research work in acoustics, conducted in a set of 12 Mudejar-Gothic churches in the city of Seville in the south of Spain. Despite common architectural style, the churches feature individual characteristics and have volumes ranging from 3947 to 10 708 m3. Acoustic parameters were measured in unoccupied churches according to the ISO-3382 standard. An extensive experimental study was carried out using impulse response analysis through a maximum length sequence measurement system in each church. It covered aspects such as reverberation (reverberation times, early decay times), distribution of sound levels (sound strength); early to late sound energy parameters derived from the impulse responses (center time, clarity for speech, clarity, definition, lateral energy fraction), and speech intelligibility (rapid speech transmission index), which all take both spectral and spatial distribution into account. Background noise was also measured to obtain the NR indices. The study describes the acoustic field inside each temple and establishes a discussion for each one of the acoustic descriptors mentioned by using the theoretical models available and the principles of architectural acoustics. Analysis of the quality of the spaces for music and speech is carried out according to the most widespread criteria for auditoria. .

  11. Acoustic Propagation Studies For Sperm Whale Phonation Analysis During LADC Experiments

    NASA Astrophysics Data System (ADS)

    Sidorovskaia, Natalia A.; Ioup, George E.; Ioup, Juliette W.; Caruthers, Jerald W.

    2004-11-01

    The Littoral Acoustic Demonstration Center (LADC) conducted a series of passive acoustic experiments in the Northern Gulf of Mexico and the Ligurian Sea in 2001 and 2002. Environmental and acoustic moorings were deployed in areas of large concentrations of marine mammals (mainly, sperm whales). Recordings and analysis of whale phonations are among the objectives of the project. Each mooring had a single autonomously recording hydrophone (Environmental Acoustic Recording System (EARS)) obtained from the U.S. Naval Oceanographic Office after modification to record signals up to 5,859 Hz in the Gulf of Mexico and up to 12,500 Hz in the Ligurian Sea. Self-recording environmental sensors, attached to the moorings, and concurrent environmental ship surveys provided the environmental data for the experiments. The results of acoustic simulations of long-range propagation of the broad-band (500-6,000 Hz) phonation pulses from a hypothetical whale location to the recording hydrophone in the experimental environments are presented. The utilization of the simulation results for an interpretation of the spectral features observed in whale clicks and for the development of tracking algorithms from single hydrophone recordings based on the identification of direct and surface and bottom reflected arrivals are discussed. [Research supported by ONR.

  12. Effects of temporal envelope modulation on acoustic signal recognition in a vocal fish, the plainfin midshipman.

    PubMed

    McKibben, J R; Bass, A H

    2001-06-01

    Amplitude modulation is an important parameter defining vertebrate acoustic communication signals. Nesting male plainfin midshipman fish, Porichthys notatus, emit simple, long duration hums in which modulation is strikingly absent. Envelope modulation is, however, introduced when the hums of adjacent males overlap to produce acoustic beats. Hums attract gravid females and can be mimicked with continuous tones at the fundamental frequency. While individual hums have flat envelopes, other midshipman signals are amplitude modulated. This study used one-choice playback tests with gravid females to examine the role of envelope modulation in hum recognition. Various pulse train and two-tone beat stimuli resembling natural communication signals were presented individually, and the responses compared to those for continuous pure tones. The effectiveness of pulse trains was graded and depended upon both pulse duration and the ratio of pulse to gap length. Midshipman were sensitive to beat modulations from 0.5 to 10 Hz, with fewer fish approaching the beat than the pure tone. Reducing the degree of modulation increased the effectiveness of beat stimuli. Hence, the lack of modulation in the midshipman's advertisement call corresponds to the importance of envelope modulation for the categorization of communication signals even in this relatively simple system. PMID:11425135

  13. A hardware model of the auditory periphery to transduce acoustic signals into neural activity

    PubMed Central

    Tateno, Takashi; Nishikawa, Jun; Tsuchioka, Nobuyoshi; Shintaku, Hirofumi; Kawano, Satoyuki

    2013-01-01

    To improve the performance of cochlear implants, we have integrated a microdevice into a model of the auditory periphery with the goal of creating a microprocessor. We constructed an artificial peripheral auditory system using a hybrid model in which polyvinylidene difluoride was used as a piezoelectric sensor to convert mechanical stimuli into electric signals. To produce frequency selectivity, the slit on a stainless steel base plate was designed such that the local resonance frequency of the membrane over the slit reflected the transfer function. In the acoustic sensor, electric signals were generated based on the piezoelectric effect from local stress in the membrane. The electrodes on the resonating plate produced relatively large electric output signals. The signals were fed into a computer model that mimicked some functions of inner hair cells, inner hair cell–auditory nerve synapses, and auditory nerve fibers. In general, the responses of the model to pure-tone burst and complex stimuli accurately represented the discharge rates of high-spontaneous-rate auditory nerve fibers across a range of frequencies greater than 1 kHz and middle to high sound pressure levels. Thus, the model provides a tool to understand information processing in the peripheral auditory system and a basic design for connecting artificial acoustic sensors to the peripheral auditory nervous system. Finally, we discuss the need for stimulus control with an appropriate model of the auditory periphery based on auditory brainstem responses that were electrically evoked by different temporal pulse patterns with the same pulse number. PMID:24324432

  14. The vocal repertoire of the domesticated zebra finch: a data-driven approach to decipher the information-bearing acoustic features of communication signals.

    PubMed

    Elie, Julie E; Theunissen, Frédéric E

    2016-03-01

    Although a universal code for the acoustic features of animal vocal communication calls may not exist, the thorough analysis of the distinctive acoustical features of vocalization categories is important not only to decipher the acoustical code for a specific species but also to understand the evolution of communication signals and the mechanisms used to produce and understand them. Here, we recorded more than 8000 examples of almost all the vocalizations of the domesticated zebra finch, Taeniopygia guttata: vocalizations produced to establish contact, to form and maintain pair bonds, to sound an alarm, to communicate distress or to advertise hunger or aggressive intents. We characterized each vocalization type using complete representations that avoided any a priori assumptions on the acoustic code, as well as classical bioacoustics measures that could provide more intuitive interpretations. We then used these acoustical features to rigorously determine the potential information-bearing acoustical features for each vocalization type using both a novel regularized classifier and an unsupervised clustering algorithm. Vocalization categories are discriminated by the shape of their frequency spectrum and by their pitch saliency (noisy to tonal vocalizations) but not particularly by their fundamental frequency. Notably, the spectral shape of zebra finch vocalizations contains peaks or formants that vary systematically across categories and that would be generated by active control of both the vocal organ (source) and the upper vocal tract (filter). PMID:26581377

  15. Coupled High Speed Imaging and Seismo-Acoustic Recordings of Strombolian Explosions at Etna, July 2014: Implications for Source Processes and Signal Inversions.

    NASA Astrophysics Data System (ADS)

    Taddeucci, J.; Del Bello, E.; Scarlato, P.; Ricci, T.; Andronico, D.; Kueppers, U.; Cannata, A.; Sesterhenn, J.; Spina, L.

    2015-12-01

    Seismic and acoustic surveillance is routinely performed at several persistent activity volcanoes worldwide. However, interpretation of the signals associated with explosive activity is still equivocal, due to both source variability and the intrinsically limited information carried by the waves. Comparison and cross-correlation of the geophysical quantities with other information in general and visual recording in particular is therefore actively sought. At Etna (Italy) in July 2014, short-lived Strombolian explosions ejected bomb- to lapilli-sized, molten pyroclasts at a remarkably repeatable time interval of about two seconds, offering a rare occasion to systematically investigate the seismic and acoustic fields radiated by this common volcanic source. We deployed FAMoUS (FAst, MUltiparametric Setup for the study of explosive activity) at 260 meters from the vents, recording more than 60 explosions in thermal and visible high-speed videos (50 to 500 frames per second) and broadband seismic and acoustic instruments (1 to 10000 Hz for the acoustic and from 0.01 to 30 Hz for the seismic). Analysis of this dataset highlights nonlinear relationships between the exit velocity and mass of ejecta and the amplitude and frequency of the acoustic signals. It also allows comparing different methods to estimate source depth, and to validate existing theory on the coupling of airwaves with ground motion.

  16. Three-dimensional coupled mode analysis of internal-wave acoustic ducts.

    PubMed

    Shmelev, Alexey A; Lynch, James F; Lin, Ying-Tsong; Schmidt, Henrik

    2014-05-01

    A fully three-dimensional coupled mode approach is used in this paper to describe the physics of low frequency acoustic signals propagating through a train of internal waves at an arbitrary azimuth. A three layer model of the shallow water waveguide is employed for studying the properties of normal modes and their coupled interaction due to the presence of nonlinear internal waves. Using a robust wave number integration technique for Fourier transform computation and a direct global matrix approach, an accurate three-dimensional coupled mode full field solution is obtained for the tonal signal propagation through straight and parallel internal waves. This approach provides accurate results for arbitrary azimuth and includes the effects of backscattering. This enables one to provide an azimuthal analysis of acoustic propagation and separate the effects of mode coupled transparent resonance, horizontal reflection and refraction, the horizontal Lloyd's mirror, horizontal ducting and anti-ducting, and horizontal tunneling and secondary ducting. PMID:24815234

  17. Perturbation analysis of electromagnetic geodesic acoustic modes

    SciTech Connect

    Ren, Haijun

    2014-06-15

    Lagrangian displacement and magnetic field perturbation response to the geodesic acoustic mode is analyzed by using the ideal magnetohydrodynamic equations in a large-aspect-ratio tokamak. δB{sub θ}, the poloidal component of magnetic field perturbation, has poloidal wave number m = 2 created by the poloidal displacement ξ{sub θ}. The parallel perturbation of magnetic field, δB{sub ∥}, has a poloidally asymmetric structure with m = 1 and is on the same order of magnitude with δB{sub θ} to the leading order. The radial displacement ξ{sub r} is of order O(βϵξ{sub θ}) but plays a significant role in determining δB{sub ∥}, where β is the plasma/magnetic pressure ratio and ϵ is the inverse aspect ratio.

  18. Acoustic Analysis Before and After Voice Therapy for Laryngeal Pathology.

    PubMed

    Chhetri, S S; Gautam, R

    2015-01-01

    Background Voice problems caused by pathologies in vocal folds are well known. Some types of laryngeal pathologies have certain acoustic characteristics. Objective evaluation helps characterize the voice and voice problems providing supporting evidences, severity of disorders. It helps assess the response to the treatment and measures the outcomes. Objective The objective of the study is to determine the effectiveness of the voice therapy and quantify the results objectively by voice parameters. Method Study includes 61 patients who presented with different types of laryngeal pathologies. Acoustic analyses and voice assessment was done with Dr. Speech ver 4 (Tiger DRS Inc.). Acoustic parameters including fundamental frequency, jitters, shimmers, Harmonic to noise ratio (HNR), Normalized noise energy (NNE) were analyzed before and after voice therapy. Result Bilateral vocal nodules were the most common pathologies comprising 44.26%. All acoustic parameters showed a significant difference after the therapy (p<0.05) except for NNE. Dysphonia due to vocal fold polyp showed no improvement even after voice therapy (p>0.05). Conclusion Acoustic analysis provides an objective, recordable data regarding the voice parameters and its pathologies. Though, few pathology require alternative therapy rather than voice therapy, overall it has a good effect on glottic closure. As the voice therapy can improve the different indices of voice, it can be viewed as imperative part of treatment and to monitor progression. PMID:27423282

  19. Influence of attenuation on acoustic emission signals in carbon fiber reinforced polymer panels.

    PubMed

    Asamene, Kassahun; Hudson, Larry; Sundaresan, Mannur

    2015-05-01

    Influence of attenuation on acoustic emission (AE) signals in Carbon Fiber Reinforced Polymer (CFRP) crossply and quasi-isotropic panels is examined in this paper. Attenuation coefficients of the fundamental antisymmetric (A0) and symmetric (S0) wave modes were determined experimentally along different directions for the two types of CFRP panels. In the frequency range from 100 kHz to 500 kHz, the A0 mode undergoes significantly greater changes due to material related attenuation compared to the S0 mode. Moderate to strong changes in the attenuation levels were noted with propagation directions. Such mode and frequency dependent attenuation introduces major changes in the characteristics of AE signals depending on the position of the AE sensor relative to the source. Results from finite element simulations of a microscopic damage event in the composite laminates are used to illustrate attenuation related changes in modal and frequency components of AE signals. PMID:25682294

  20. Noise affects the shape of female preference functions for acoustic signals.

    PubMed

    Reichert, Michael S; Ronacher, Bernhard

    2015-02-01

    The shape of female mate preference functions influences the speed and direction of sexual signal evolution. However, the expression of female preferences is modulated by interactions between environmental conditions and the female's sensory processing system. Noise is an especially relevant environmental condition because it interferes directly with the neural processing of signals. Although noise is therefore likely a significant force in the evolution of communication systems, little is known about its effects on preference function shape. In the grasshopper Chorthippus biguttulus, female preferences for male calling song characteristics are likely to be affected by noise because its auditory system is sensitive to fine temporal details of songs. We measured female preference functions for variation in male song characteristics in several levels of masking noise and found strong effects of noise on preference function shape. The overall responsiveness to signals in noise generally decreased. Preference strength increased for some signal characteristics and decreased for others, largely corresponding to expectations based on neurophysiological studies of acoustic signal processing. These results suggest that different signal characteristics will be favored under different noise conditions, and thus that signal evolution may proceed differently depending on the extent and temporal patterning of environmental noise. PMID:25546134

  1. Predictions of acoustic signals from explosions above and below the ocean surface: source region calculations

    SciTech Connect

    Clarke, D.B.; Piacsek, A.; White, J.W.

    1996-12-01

    In support of the Comprehensive Test Ban, research is underway on the long range propagation of signals from nuclear explosions in the deep underwater sound (SOFAR) channel. This first phase of our work at LLNL on signals in the source regions considered explosions in or above the deep (5000 m) ocean. We studied the variation of wave properties and source region energy coupling as a function of height or depth of burst. Initial calculations on CALE, a two-dimensional hydrodynamics code developed at LLNL by Robert Tipton, were linked at a few hundred milliseconds to a version of NRL`s weak shock code, NPE, which solves the nonlinear progressive wave equation. The wave propagation simulation was performed down to 5000 m depth and out to 10,000 m range. We have developed a procedure to convert the acoustic signals at 10 km range into `starter fields` for calculations on a linear acoustics code which will extend the propagation to ocean basin distances. Recently we have completed calculations to evaluate environmental effects (shallow water, bottom interactions) on signal propagation. We compared results at 25 km range from three calculations of the same I kiloton burst (50 m height-of-burst) in three different environments, namely, deep water, shallow water, and a case with shallow water sloping to deep water. Several results from this last `sloping bottom` case will be 2016 discussed below. In this shallow water study, we found that propagation through shallow water complicates and attenuates the signal; the changes made to the signal may impact detection and discrimination for bursts in some locations.

  2. Signal diversification in Oecanthus tree crickets is shaped by energetic, morphometric, and acoustic trade-offs.

    PubMed

    Symes, L B; Ayres, M P; Cowdery, C P; Costello, R A

    2015-06-01

    Physiology, physics, and ecological interactions can generate trade-offs within species, but may also shape divergence among species. We tested whether signal divergence in Oecanthus tree crickets is shaped by acoustic, energetic, and behavioral trade-offs. We found that species with faster pulse rates, produced by opening and closing wings up to twice as many times per second, did not have higher metabolic costs of calling. The relatively constant energetic cost across species is explained by trade-offs between the duration and repetition rate of acoustic signals-species with fewer stridulatory teeth closed their wings more frequently such that the number of teeth struck per second of calling and the resulting duty cycle were relatively constant across species. Further trade-offs were evident in relationships between signals and body size. Calling was relatively inexpensive for small males, permitting them to call for much of the night, but at low amplitude. Large males produced much louder calls, reaching up to four times more area, but the energetic costs increased substantially with increasing size and the time spent calling dropped to only 20% of the night. These trade-offs indicate that the trait combinations that arise in these species represent a limited subset of conceivable trait combinations. PMID:25903317

  3. The potential influence of morphology on the evolutionary divergence of an acoustic signal

    PubMed Central

    Pitchers, W. R.; Klingenberg, C.P.; Tregenza, Tom; Hunt, J.; Dworkin, I.

    2014-01-01

    The evolution of acoustic behaviour and that of the morphological traits mediating its production are often coupled. Lack of variation in the underlying morphology of signalling traits has the potential to constrain signal evolution. This relationship is particularly likely in field crickets, where males produce acoustic advertisement signals to attract females by stridulating with specialized structures on their forewings. In this study, we characterise the size and geometric shape of the forewings of males from six allopatric populations of the black field cricket (Teleogryllus commodus) known to have divergent advertisement calls. We sample from each of these populations using both wild-caught and common-garden reared cohorts, allowing us to test for multivariate relationships between wing morphology and call structure. We show that the allometry of shape has diverged across populations. However, there was a surprisingly small amount of covariation between wing shape and call structure within populations. Given the importance of male size for sexual selection in crickets, the divergence we observe among populations has the potential to influence the evolution of advertisement calls in this species. PMID:25223712

  4. The potential influence of morphology on the evolutionary divergence of an acoustic signal.

    PubMed

    Pitchers, W R; Klingenberg, C P; Tregenza, T; Hunt, J; Dworkin, I

    2014-10-01

    The evolution of acoustic behaviour and that of the morphological traits mediating its production are often coupled. Lack of variation in the underlying morphology of signalling traits has the potential to constrain signal evolution. This relationship is particularly likely in field crickets, where males produce acoustic advertisement signals to attract females by stridulating with specialized structures on their forewings. In this study, we characterize the size and geometric shape of the forewings of males from six allopatric populations of the black field cricket (Teleogryllus commodus) known to have divergent advertisement calls. We sample from each of these populations using both wild-caught and common-garden-reared cohorts, allowing us to test for multivariate relationships between wing morphology and call structure. We show that the allometry of shape has diverged across populations. However, there was a surprisingly small amount of covariation between wing shape and call structure within populations. Given the importance of male size for sexual selection in crickets, the divergence we observe among populations has the potential to influence the evolution of advertisement calls in this species. PMID:25223712

  5. Acoustical analysis of mechanical heart valve sounds for early detection of malfunction.

    PubMed

    Famaey, Nele; Defever, Korijn; Bielen, Paul; Flameng, Willem; Vander Sloten, Jos; Sas, Paul; Meuris, Bart

    2010-10-01

    Mechanical heart valves carry the disadvantage of lifelong antithrombotic therapy, due to the high risk of thrombus formation on the valve surface. Current diagnostic methods are incapable of detecting thrombus formation in an early stage. This article investigates a new diagnostic method, based on the analysis of the acoustic signal produced by the valve. This method should be capable of early detection of malfunction, thus permitting targeted medication and reducing valve-related complications and mortality. A measurement setup assuring optimal signal quality was developed, and a signal analysis program was implemented and validated on an in vitro mock circulatory loop. Next, four sheep were implanted with a bileaflet mechanical valve. The signals of their valves developing thrombosis were assessed on a weekly basis before explantation. Three sheep were sacrificed shortly after detection of malfunction according to the newly developed method. In each case, thrombus or membrane formation was detected on the leaflets upon explantation. In one sheep, no malfunction was found in the analysis, which was also confirmed by the condition of the valve upon explantation. These preliminary results indicate that acoustical analysis of mechanical heart valves permits early detection of valvular malfunction. Further research with more in vitro and animal testing is required to statistically validate these findings. PMID:20573536

  6. Long Recording Sequences: How to Track the Intra-Individual Variability of Acoustic Signals

    PubMed Central

    Lengagne, Thierry; Gomez, Doris; Josserand, Rémy; Voituron, Yann

    2015-01-01

    Recently developed acoustic technologies - like automatic recording units - allow the recording of long sequences in natural environments. These devices are used for biodiversity survey but they could also help researchers to estimate global signal variability at various (individual, population, species) scales. While sexually-selected signals are expected to show a low intra-individual variability at relatively short time scale, this variability has never been estimated so far. Yet, measuring signal variability in controlled conditions should prove useful to understand sexual selection processes and should help design acoustic sampling schedules and to analyse long call recordings. We here use the overall call production of 36 male treefrogs (Hyla arborea) during one night to evaluate within-individual variability in call dominant frequency and to test the efficiency of different sampling methods at capturing such variability. Our results confirm that using low number of calls underestimates call dominant frequency variation of about 35% in the tree frog and suggest that the assessment of this variability is better by using 2 or 3 short and well-distributed records than by using samples made of consecutive calls. Hence, 3 well-distributed 2-minutes records (beginning, middle and end of the calling period) are sufficient to capture on average all the nightly variability, whereas a sample of 10 000 consecutive calls captures only 86% of it. From a biological point of view, the call dominant frequency variability observed in H. arborea (116Hz on average but up to 470 Hz of variability during the course of the night for one male) challenge about its reliability in mate quality assessment. Automatic acoustic recording units will provide long call sequences in the near future and it will be then possible to confirm such results on large samples recorded in more complex field conditions. PMID:25970183

  7. Heterodyne signal-to-noise ratios in acoustic mode scattering experiments

    NASA Technical Reports Server (NTRS)

    Cochran, W. R.

    1980-01-01

    The relation between the signal to noise ratio (SNR) obtained in heterodyne detection of radiation scattered from acoustic modes in crystalline solids and the scattered spectral density function is studied. It is shown that in addition to the information provided by the measured frequency shifts and line widths, measurement of the SNR provides a determination of the absolute elasto-optical (Pockel's) constants. Examples are given for cubic crystals, and acceptable SNR values are obtained for scattering from thermally excited phonons at 10.6 microns, with no external perturbation of the sample necessary. The results indicate the special advantages of the method for the study of semiconductors.

  8. Mate preference in the painted goby: the influence of visual and acoustic courtship signals.

    PubMed

    Amorim, M Clara P; da Ponte, Ana Nunes; Caiano, Manuel; Pedroso, Silvia S; Pereira, Ricardo; Fonseca, Paulo J

    2013-11-01

    We tested the hypothesis that females of a small vocal marine fish with exclusive paternal care, the painted goby, prefer high parental-quality mates such as large or high-condition males. We tested the effect of male body size and male visual and acoustic courtship behaviour (playback experiments) on female mating preferences by measuring time spent near one of a two-choice stimuli. Females did not show preference for male size but preferred males that showed higher levels of courtship, a trait known to advertise condition (fat reserves). Also, time spent near the preferred male depended on male courtship effort. Playback experiments showed that when sound was combined with visual stimuli (a male confined in a small aquarium placed near each speaker), females spent more time near the male associated with courtship sound than with the control male (associated with white noise or silence). Although male visual courtship effort also affected female preference in the pre-playback period, this effect decreased during playback and disappeared in the post-playback period. Courtship sound stimuli alone did not elicit female preference in relation to a control. Taken together, the results suggest that visual and mainly acoustic courtship displays are subject to mate preference and may advertise parental quality in this species. Our results indicate that visual and acoustic signals interplay in a complex fashion and highlight the need to examine how different sensory modalities affect mating preferences in fish and other vertebrates. PMID:23948469

  9. Neural Mechanisms for Acoustic Signal Detection under Strong Masking in an Insect.

    PubMed

    Kostarakos, Konstantinos; Römer, Heiner

    2015-07-22

    Communication is fundamental for our understanding of behavior. In the acoustic modality, natural scenes for communication in humans and animals are often very noisy, decreasing the chances for signal detection and discrimination. We investigated the mechanisms enabling selective hearing under natural noisy conditions for auditory receptors and interneurons of an insect. In the studied katydid Mecopoda elongata species-specific calling songs (chirps) are strongly masked by signals of another species, both communicating in sympatry. The spectral properties of the two signals are similar and differ only in a small frequency band at 2 kHz present in the chirping species. Receptors sharply tuned to 2 kHz are completely unaffected by the masking signal of the other species, whereas receptors tuned to higher audio and ultrasonic frequencies show complete masking. Intracellular recordings of identified interneurons revealed two mechanisms providing response selectivity to the chirp. (1) Response selectivity is when several identified interneurons exhibit remarkably selective responses to the chirps, even at signal-to-noise ratios of -21 dB, since they are sharply tuned to 2 kHz. Their dendritic arborizations indicate selective connectivity with low-frequency receptors tuned to 2 kHz. (2) Novelty detection is when a second group of interneurons is broadly tuned but, because of strong stimulus-specific adaptation to the masker spectrum and "novelty detection" to the 2 kHz band present only in the conspecific signal, these interneurons start to respond selectively to the chirp shortly after the onset of the continuous masker. Both mechanisms provide the sensory basis for hearing at unfavorable signal-to-noise ratios. Significance statement: Animal and human acoustic communication may suffer from the same "cocktail party problem," when communication happens in noisy social groups. We address solutions for this problem in a model system of two katydids, where one species

  10. Neural Mechanisms for Acoustic Signal Detection under Strong Masking in an Insect

    PubMed Central

    Römer, Heiner

    2015-01-01

    Communication is fundamental for our understanding of behavior. In the acoustic modality, natural scenes for communication in humans and animals are often very noisy, decreasing the chances for signal detection and discrimination. We investigated the mechanisms enabling selective hearing under natural noisy conditions for auditory receptors and interneurons of an insect. In the studied katydid Mecopoda elongata species-specific calling songs (chirps) are strongly masked by signals of another species, both communicating in sympatry. The spectral properties of the two signals are similar and differ only in a small frequency band at 2 kHz present in the chirping species. Receptors sharply tuned to 2 kHz are completely unaffected by the masking signal of the other species, whereas receptors tuned to higher audio and ultrasonic frequencies show complete masking. Intracellular recordings of identified interneurons revealed two mechanisms providing response selectivity to the chirp. (1) Response selectivity is when several identified interneurons exhibit remarkably selective responses to the chirps, even at signal-to-noise ratios of −21 dB, since they are sharply tuned to 2 kHz. Their dendritic arborizations indicate selective connectivity with low-frequency receptors tuned to 2 kHz. (2) Novelty detection is when a second group of interneurons is broadly tuned but, because of strong stimulus-specific adaptation to the masker spectrum and “novelty detection” to the 2 kHz band present only in the conspecific signal, these interneurons start to respond selectively to the chirp shortly after the onset of the continuous masker. Both mechanisms provide the sensory basis for hearing at unfavorable signal-to-noise ratios. SIGNIFICANCE STATEMENT Animal and human acoustic communication may suffer from the same “cocktail party problem,” when communication happens in noisy social groups. We address solutions for this problem in a model system of two katydids, where one

  11. Continuous perception and graded categorization: Electrophysiological evidence for a linear relationship between the acoustic signal and perceptual encoding of speech

    PubMed Central

    Toscano, Joseph C.; McMurray, Bob; Dennhardt, Joel; Luck, Steven. J.

    2012-01-01

    Speech sounds are highly variable, yet listeners readily extract information from them and transform continuous acoustic signals into meaningful categories during language comprehension. A central question is whether perceptual encoding captures continuous acoustic detail in a one-to-one fashion or whether it is affected by categories. We addressed this in an event-related potential (ERP) experiment in which listeners categorized spoken words that varied along a continuous acoustic dimension (voice onset time; VOT) in an auditory oddball task. We found that VOT effects were present through a late stage of perceptual processing (N1 component, ca. 100 ms poststimulus) and were independent of categories. In addition, effects of within-category differences in VOT were present at a post-perceptual categorization stage (P3 component, ca. 450 ms poststimulus). Thus, at perceptual levels, acoustic information is encoded continuously, independent of phonological information. Further, at phonological levels, fine-grained acoustic differences are preserved along with category information. PMID:20935168

  12. Acoustic analysis of an Olmecan whistle

    NASA Astrophysics Data System (ADS)

    Beristain, Sergio; Menchaca, Rolando; Velazquez, Roberto

    2002-05-01

    Thousands of stone artifacts over 2500 years of age have been found in the Olmecan area in the southeast region of Mexico. These range from the famous big heads with helmets (about 2 m in diameter), to small pieces with precisely drilled holes, which some archaeologists consider to have some simple uses, much simpler than the work needed to produce the stone artifact itself. The one studied here (about 3 cm in size), is considered by the acoustics community as an air-phone, and a detailed anaysis has been done employing FFT techniques in order to find out the frequency spread, the particular tones produced and the sound radiated power through the different holes and cavities. The artifact is made of a very solid stone, so-called ilmenite, believed to have titanium, which is very hard to drill. Nevertheless, many similar pieces have been found in the area, which means they were built on purpose, and the material used gives the idea of a sacred application. Attempts have been made to reproduce the artifacts, which produce sounds similar to those from the original pieces.

  13. Structure analysis using acoustically levitated droplets.

    PubMed

    Leiterer, J; Delissen, F; Emmerling, F; Thünemann, A F; Panne, U

    2008-06-01

    Synchrotron diffraction with a micrometer-sized X-ray beam permits the efficient characterization of micrometer-sized samples, even in time-resolved experiments, which is important because often the amount of sample available is small and/or the sample is expensive. In this context, we will present acoustic levitation as a useful sample handling method for small solid and liquid samples, which are suspended in a gaseous environment (air) by means of a stationary ultrasonic field. A study of agglomeration and crystallization processes in situ was performed by continuously increasing the concentration of the samples by evaporating the solvent. Absorption and contamination processes on the sample container walls were suppressed strongly by this procedure, and parasitic scattering such as that observed when using glass capillaries was also absent. The samples investigated were either dissolved or dispersed in water droplets with diameters in the range of 1 micrometer to 2 millimeters. Initial results from time-resolved synchrotron small- and wide-angle X-ray scattering measurements of ascorbic acid, acetylsalicylic acid, apoferritin, and colloidal gold are presented. PMID:18373085

  14. A Flexible Analysis Tool for the Quantitative Acoustic Assessment of Infant Cry

    PubMed Central

    Reggiannini, Brian; Sheinkopf, Stephen J.; Silverman, Harvey F.; Li, Xiaoxue; Lester, Barry M.

    2015-01-01

    Purpose In this article, the authors describe and validate the performance of a modern acoustic analyzer specifically designed for infant cry analysis. Method Utilizing known algorithms, the authors developed a method to extract acoustic parameters describing infant cries from standard digital audio files. They used a frame rate of 25 ms with a frame advance of 12.5 ms. Cepstral-based acoustic analysis proceeded in 2 phases, computing frame-level data and then organizing and summarizing this information within cry utterances. Using signal detection methods, the authors evaluated the accuracy of the automated system to determine voicing and to detect fundamental frequency (F0) as compared to voiced segments and pitch periods manually coded from spectrogram displays. Results The system detected F0 with 88% to 95% accuracy, depending on tolerances set at 10 to 20 Hz. Receiver operating characteristic analyses demonstrated very high accuracy at detecting voicing characteristics in the cry samples. Conclusions This article describes an automated infant cry analyzer with high accuracy to detect important acoustic features of cry. A unique and important aspect of this work is the rigorous testing of the system’s accuracy as compared to ground-truth manual coding. The resulting system has implications for basic and applied research on infant cry development. PMID:23785178

  15. Clustering reveals cavitation-related acoustic emission signals from dehydrating branches.

    PubMed

    Vergeynst, Lidewei L; Sause, Markus G R; De Baerdemaeker, Niels J F; De Roo, Linus; Steppe, Kathy

    2016-06-01

    The formation of air emboli in the xylem during drought is one of the key processes leading to plant mortality due to loss in hydraulic conductivity, and strongly fuels the interest in quantifying vulnerability to cavitation. The acoustic emission (AE) technique can be used to measure hydraulic conductivity losses and construct vulnerability curves. For years, it has been believed that all the AE signals are produced by the formation of gas emboli in the xylem sap under tension. More recent experiments, however, demonstrate that gas emboli formation cannot explain all the signals detected during drought, suggesting that different sources of AE exist. This complicates the use of the AE technique to measure emboli formation in plants. We therefore analysed AE waveforms measured on branches of grapevine (Vitis vinifera L. 'Chardonnay') during bench dehydration with broadband sensors, and applied an automated clustering algorithm in order to find natural clusters of AE signals. We used AE features and AE activity patterns during consecutive dehydration phases to identify the different AE sources. Based on the frequency spectrum of the signals, we distinguished three different types of AE signals, of which the frequency cluster with high 100-200 kHz frequency content was strongly correlated with cavitation. Our results indicate that cavitation-related AE signals can be filtered from other AE sources, which presents a promising avenue into quantifying xylem embolism in plants in laboratory and field conditions. PMID:27095256

  16. Optical observations of meteors generating infrasound-I: Acoustic signal identification and phenomenology

    NASA Astrophysics Data System (ADS)

    Silber, Elizabeth A.; Brown, Peter G.

    2014-11-01

    We analyse infrasound signals from 71 bright meteors/fireballs simultaneously detected by video to investigate the phenomenology and characteristics of meteor-generated near-field infrasound (<300 km) and shock production. A taxonomy for meteor generated infrasound signal classification has been developed using the time-pressure signal of the infrasound arrivals. Based on the location along the meteor trail where the infrasound signal originates, we find most signals are associated with cylindrical shocks, with about a quarter of events evidencing spherical shocks associated with fragmentation episodes and optical flares. The video data indicate that all events with ray launch angles >117° from the trajectory heading are most likely generated by a spherical shock, while infrasound produced by the meteors with ray launch angles ≤117° can be attributed to both a cylindrical line source and a spherical shock. We find that meteors preferentially produce infrasound toward the end of their trails with a smaller number showing a preference for mid-trail production. Meteors producing multiple infrasound arrivals show a strong infrasound source height skewness to the end of trails and are much more likely to be associated with optical flares. We find that about 1% of all our optically-recorded meteors have associated detected infrasound and estimate that regional meteor infrasound events should occur on the order of once per week and dominate in numbers over infrasound associated with more energetic (but rarer) bolides. While a significant fraction of our meteors generating infrasound (~1/4 of single arrivals) are produced by fragmentation events, we find no instances where acoustic radiation is detectable more than about 60° beyond the ballistic regime at our meteoroid sizes (grams to tens of kilograms) emphasizing the strong anisotropy in acoustic radiation for meteors which are dominated by cylindrical line source geometry, even in the presence of fragmentation.

  17. Multiple target tracking and classification improvement using data fusion at node level using acoustic signals

    NASA Astrophysics Data System (ADS)

    Damarla, T. R.; Whipps, Gene

    2005-05-01

    Target tracking and classification using passive acoustic signals is difficult at best as the signals are contaminated by wind noise, multi-path effects, road conditions, and are generally not deterministic. In addition, microphone characteristics, such as sensitivity, vary with the weather conditions. The problem is further compounded if there are multiple targets, especially if some are measured with higher signal-to-noise ratios (SNRs) than the others and they share spectral information. At the U. S. Army Research Laboratory we have conducted several field experiments with a convoy of two, three, four and five vehicles traveling on different road surfaces, namely gravel, asphalt, and dirt roads. The largest convoy is comprised of two tracked vehicles and three wheeled vehicles. Two of the wheeled vehicles are heavy trucks and one is a light vehicle. We used a super-resolution direction-of-arrival estimator, specifically the minimum variance distortionless response, to compute the bearings of the targets. In order to classify the targets, we modeled the acoustic signals emanated from the targets as a set of coupled harmonics, which are related to the engine-firing rate, and subsequently used a multivariate Gaussian classifier. Independent of the classifier, we find tracking of wheeled vehicles to be intermittent as the signals from vehicles with high SNR dominate the much quieter wheeled vehicles. We used several fusion techniques to combine tracking and classification results to improve final tracking and classification estimates. We will present the improvements (or losses) made in tracking and classification of all targets. Although improvements in the estimates for tracked vehicles are not noteworthy, significant improvements are seen in the case of wheeled vehicles. We will present the fusion algorithm used.

  18. Degradation of Coherence of Acoustic Signals Resulting from Inhomogeneities in the Sea.

    NASA Astrophysics Data System (ADS)

    Dobbins, Peter F.

    Available from UMI in association with The British Library. This thesis attempts to answer the question 'Is there an ultimate limit to the resolution of a sonar transducer due to sea water inhomogeneity?' The problem has been separated into three components: the sea water medium, acoustic propagation through this random medium, and the effects of the resulting phase and amplitude fluctuations on the performance of transducer arrays. The model for the medium is based on a spatial spectrum of the fluctuations in temperature and refractive index, and is divided into wavenumber ranges where phenomena such as turbulence of viscous dissipation dominate. The model for acoustic propagation uses the Rytov method, assuming that multiple scattering is not significant. The effects of fluctuations of array directivity were investigated using both numerical simulations and theory based on the plane wave spectrum. Laboratory experiments were conducted to confirm aspects of the propagation theory. Experiments at sea were carried out to validate the model of the medium; profiles of temperature, salinity, sound speed and current velocity were measured, and good agreement with the model was obtained in all cases. These data were used with the propagation theory to determine spatial correlation functions of phase and amplitude fluctuations in acoustic signals at a number of frequencies. Finally, these results were used to estimate the changes in beampattern for arrays of various sizes. It was found that there is a limit to the angular resolution of a linear array, determined by the width of the plane wave spectrum, and this limit is reached when the length of the array approaches the correlation scale of the acoustic fluctuations.

  19. Bayesian probability analysis for acoustic-seismic landmine detection

    NASA Astrophysics Data System (ADS)

    Xiang, Ning; Sabatier, James M.; Goggans, Paul M.

    2002-11-01

    Landmines buried in the subsurface induce distinct changes in the seismic vibration of the ground surface when an acoustic source insonifies the ground. A scanning laser Doppler vibrometer (SLDV) senses the acoustically-induced seismic vibration of the ground surface in a noncontact, remote manner. The SLDV-based acoustic-to-seismic coupling technology exhibits significant advantages over conventional sensors due to its capability for detecting both metal and nonmetal mines and its stand-off distance. The seismic vibration data scanned from the SLDV are preprocessed to form images. The detection of landmines relies primarily on an analysis of the target amplitude, size, shape, and frequency range. A parametric model has been established [Xiang and Sabatier, J. Acoust. Soc. Am. 110, 2740 (2001)] to describe the amplified surface vibration velocity induced by buried landmines within an appropriate frequency range. This model incorporates vibrational amplitude, size, position of landmines, and the background amplitude into a model-based analysis process in which Bayesian target detection and parameter estimation have been applied. Based on recent field measurement results, the landmine detection procedure within a Bayesian framework will be discussed. [Work supported by the United States Army Communications-Electronics Command, Night Vision and Electronic Sensors Directorate.

  20. System and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources

    DOEpatents

    Holzrichter, John F.; Burnett, Greg C.; Ng, Lawrence C.

    2007-10-16

    A system and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources is disclosed. Propagating wave electromagnetic sensors monitor excitation sources in sound producing systems, such as machines, musical instruments, and various other structures. Acoustical output from these sound producing systems is also monitored. From such information, a transfer function characterizing the sound producing system is generated. From the transfer function, acoustical output from the sound producing system may be synthesized or canceled. The methods disclosed enable accurate calculation of matched transfer functions relating specific excitations to specific acoustical outputs. Knowledge of such signals and functions can be used to effect various sound replication, sound source identification, and sound cancellation applications.

  1. System and method for characterizing synthesizing and/or canceling out acoustic signals from inanimate sound sources

    DOEpatents

    Holzrichter, John F.; Burnett, Greg C.; Ng, Lawrence C.

    2003-01-01

    A system and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources is disclosed. Propagating wave electromagnetic sensors monitor excitation sources in sound producing systems, such as machines, musical instruments, and various other structures. Acoustical output from these sound producing systems is also monitored. From such information, a transfer function characterizing the sound producing system is generated. From the transfer function, acoustical output from the sound producing system may be synthesized or canceled. The methods disclosed enable accurate calculation of matched transfer functions relating specific excitations to specific acoustical outputs. Knowledge of such signals and functions can be used to effect various sound replication, sound source identification, and sound cancellation applications.

  2. System and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources

    DOEpatents

    Holzrichter, John F; Burnett, Greg C; Ng, Lawrence C

    2013-05-21

    A system and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources is disclosed. Propagating wave electromagnetic sensors monitor excitation sources in sound producing systems, such as machines, musical instruments, and various other structures. Acoustical output from these sound producing systems is also monitored. From such information, a transfer function characterizing the sound producing system is generated. From the transfer function, acoustical output from the sound producing system may be synthesized or canceled. The methods disclosed enable accurate calculation of matched transfer functions relating specific excitations to specific acoustical outputs. Knowledge of such signals and functions can be used to effect various sound replication, sound source identification, and sound cancellation applications.

  3. Acoustic Analysis of Speech of Cochlear Implantees and Its Implications

    PubMed Central

    Patadia, Rajesh; Govale, Prajakta; Rangasayee, R.; Kirtane, Milind

    2012-01-01

    Objectives Cochlear implantees have improved speech production skills compared with those using hearing aids, as reflected in their acoustic measures. When compared to normal hearing controls, implanted children had fronted vowel space and their /s/ and /∫/ noise frequencies overlapped. Acoustic analysis of speech provides an objective index of perceived differences in speech production which can be precursory in planning therapy. The objective of this study was to compare acoustic characteristics of speech in cochlear implantees with those of normal hearing age matched peers to understand implications. Methods Group 1 consisted of 15 children with prelingual bilateral severe-profound hearing loss (age, 5-11 years; implanted between 4-10 years). Prior to an implant behind the ear, hearing aids were used; prior & post implantation subjects received at least 1 year of aural intervention. Group 2 consisted of 15 normal hearing age matched peers. Sustained productions of vowels and words with selected consonants were recorded. Using Praat software for acoustic analysis, digitized speech tokens were measured for F1, F2, and F3 of vowels; centre frequency (Hz) and energy concentration (dB) in burst; voice onset time (VOT in ms) for stops; centre frequency (Hz) of noise in /s/; rise time (ms) for affricates. A t-test was used to find significant differences between groups. Results Significant differences were found in VOT for /b/, F1 and F2 of /e/, and F3 of /u/. No significant differences were found for centre frequency of burst, energy concentration for stops, centre frequency of noise in /s/, or rise time for affricates. These findings suggest that auditory feedback provided by cochlear implants enable subjects to monitor production of speech sounds. Conclusion Acoustic analysis of speech is an essential method for discerning characteristics which have or have not been improved by cochlear implantation and thus for planning intervention. PMID:22701768

  4. Signal-to-noise ratio for acoustic detection in the deep ocean

    NASA Technical Reports Server (NTRS)

    Bowen, T.

    1979-01-01

    A simple method is presented for studying the thermoacoustic wave generated by a heat pulse. The signal-to-noise ratio (S/N) is then calculated for a typical hadronic-electromagnetic cascade in the deep ocean where low frequencies are masked by surface noise. It is found that a maximum useful range of about 16 km is found for typical conditions at 5 km depth. It is shown that in order to obtain useful signals with S/N greater than 100 at distances of 1 to 16 km, the cascade energy must be 10 to the 16th to 10 to the 18th eV. Finally, attention is given to further refinements of the theory of acoustic detection which remain to be investigated.

  5. Detection of Delamination in Concrete Bridge Decks Using Mfcc of Acoustic Impact Signals

    NASA Astrophysics Data System (ADS)

    Zhang, G.; Harichandran, R. S.; Ramuhalli, P.

    2010-02-01

    Delamination of the concrete cover is a commonly observed damage in concrete bridge decks. The delamination is typically initiated by corrosion of the upper reinforcing bars and promoted by freeze-thaw cycling and traffic loading. The detection of delamination is important for bridge maintenance and acoustic non-destructive evaluation (NDE) is widely used due to its low cost, speed, and easy implementation. In traditional acoustic approaches, the inspector sounds the surface of the deck by impacting it with a hammer or bar, or by dragging a chain, and assesses delamination by the "hollowness" of the sound. The detection of the delamination is subjective and requires extensive training. To improve performance, this paper proposes an objective method for delamination detection. In this method, mel-frequency cepstral coefficients (MFCC) of the signal are extracted. Some MFCC are then selected as features for detection purposes using a mutual information criterion. Finally, the selected features are used to train a classifier which is subsequently used for detection. In this work, a simple quadratic Bayesian classifier is used. Different numbers of features are used to compare the performance of the detection method. The results show that the performance first increases with the number of features, but then decreases after an optimal value. The optimal number of features based on the recorded signals is four, and the mean error rate is only 3.3% when four features are used. Therefore, the proposed algorithm has sufficient accuracy to be used in field detection.

  6. Processing of simple and complex acoustic signals in a tonotopically organized ear

    PubMed Central

    Hummel, Jennifer; Wolf, Konstantin; Kössl, Manfred; Nowotny, Manuela

    2014-01-01

    Processing of complex signals in the hearing organ remains poorly understood. This paper aims to contribute to this topic by presenting investigations on the mechanical and neuronal response of the hearing organ of the tropical bushcricket species Mecopoda elongata to simple pure tone signals as well as to the conspecific song as a complex acoustic signal. The high-frequency hearing organ of bushcrickets, the crista acustica (CA), is tonotopically tuned to frequencies between about 4 and 70 kHz. Laser Doppler vibrometer measurements revealed a strong and dominant low-frequency-induced motion of the CA when stimulated with either pure tone or complex stimuli. Consequently, the high-frequency distal area of the CA is more strongly deflected by low-frequency-induced waves than by high-frequency-induced waves. This low-frequency dominance will have strong effects on the processing of complex signals. Therefore, we additionally studied the neuronal response of the CA to native and frequency-manipulated chirps. Again, we found a dominant influence of low-frequency components within the conspecific song, indicating that the mechanical vibration pattern highly determines the neuronal response of the sensory cells. Thus, we conclude that the encoding of communication signals is modulated by ear mechanics. PMID:25339727

  7. Processing of simple and complex acoustic signals in a tonotopically organized ear.

    PubMed

    Hummel, Jennifer; Wolf, Konstantin; Kössl, Manfred; Nowotny, Manuela

    2014-12-01

    Processing of complex signals in the hearing organ remains poorly understood. This paper aims to contribute to this topic by presenting investigations on the mechanical and neuronal response of the hearing organ of the tropical bushcricket species Mecopoda elongata to simple pure tone signals as well as to the conspecific song as a complex acoustic signal. The high-frequency hearing organ of bushcrickets, the crista acustica (CA), is tonotopically tuned to frequencies between about 4 and 70 kHz. Laser Doppler vibrometer measurements revealed a strong and dominant low-frequency-induced motion of the CA when stimulated with either pure tone or complex stimuli. Consequently, the high-frequency distal area of the CA is more strongly deflected by low-frequency-induced waves than by high-frequency-induced waves. This low-frequency dominance will have strong effects on the processing of complex signals. Therefore, we additionally studied the neuronal response of the CA to native and frequency-manipulated chirps. Again, we found a dominant influence of low-frequency components within the conspecific song, indicating that the mechanical vibration pattern highly determines the neuronal response of the sensory cells. Thus, we conclude that the encoding of communication signals is modulated by ear mechanics. PMID:25339727

  8. Statistical analysis of storm electrical discharges reconstituted from a lightning mapping system, a lightning location system, and an acoustic array

    NASA Astrophysics Data System (ADS)

    Gallin, Louis-Jonardan; Farges, Thomas; Marchiano, Régis; Coulouvrat, François; Defer, Eric; Rison, William; Schulz, Wolfgang; Nuret, Mathieu

    2016-04-01

    In the framework of the European Hydrological Cycle in the Mediterranean Experiment project, a field campaign devoted to the study of electrical activity during storms took place in the south of France in 2012. An acoustic station composed of four microphones and four microbarometers was deployed within the coverage of a Lightning Mapping Array network. On the 26 October 2012, a thunderstorm passed just over the acoustic station. Fifty-six natural thunder events, due to cloud-to-ground and intracloud flashes, were recorded. This paper studies the acoustic reconstruction, in the low frequency range from 1 to 40 Hz, of the recorded flashes and their comparison with detections from electromagnetic networks. Concurrent detections from the European Cooperation for Lightning Detection lightning location system were also used. Some case studies show clearly that acoustic signal from thunder comes from the return stroke but also from the horizontal discharges which occur inside the clouds. The huge amount of observation data leads to a statistical analysis of lightning discharges acoustically recorded. Especially, the distributions of altitudes of reconstructed acoustic detections are explored in detail. The impact of the distance to the source on these distributions is established. The capacity of the acoustic method to describe precisely the lower part of nearby cloud-to-ground discharges, where the Lightning Mapping Array network is not effective, is also highlighted.

  9. An analysis of blade vortex interaction aerodynamics and acoustics

    NASA Technical Reports Server (NTRS)

    Lee, D. J.

    1985-01-01

    The impulsive noise associated with helicopter flight due to Blade-Vortex Interaction, sometimes called blade slap is analyzed especially for the case of a close encounter of the blade-tip vortex with a following blade. Three parts of the phenomena are considered: the tip-vortex structure generated by the rotating blade, the unsteady pressure produced on the following blade during the interaction, and the acoustic radiation due to the unsteady pressure field. To simplify the problem, the analysis was confined to the situation where the vortex is aligned parallel to the blade span in which case the maximum acoustic pressure results. Acoustic radiation due to the interaction is analyzed in space-fixed coordinates and in the time domain with the unsteady pressure on the blade surface as the source of chordwise compact, but spanwise non-compact radiation. Maximum acoustic pressure is related to the vortex core size and Reynolds number which are in turn functions of the blade-tip aerodynamic parameters. Finally noise reduction and performance are considered.

  10. The discrimination of man-made explosions from earthquakes using seismo-acoustic analysis in the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Che, Il-Young; Jeon, Jeong-Soo

    2010-05-01

    Korea Institute of Geoscience and Mineral Resources (KIGAM) operates an infrasound network consisting of seven seismo-acoustic arrays in South Korea. Development of the arrays began in 1999, partially in collaboration with Southern Methodist University, with the goal of detecting distant infrasound signals from natural and anthropogenic phenomena in and around the Korean Peninsula. The main operational purpose of this network is to discriminate man-made seismic events from seismicity including thousands of seismic events per year in the region. The man-made seismic events are major cause of error in estimating the natural seismicity, especially where the seismic activity is weak or moderate such as in the Korean Peninsula. In order to discriminate the man-made explosions from earthquakes, we have applied the seismo-acoustic analysis associating seismic and infrasonic signals generated from surface explosion. The observations of infrasound at multiple arrays made it possible to discriminate surface explosion, because small or moderate size earthquake is not sufficient to generate infrasound. Till now we have annually discriminated hundreds of seismic events in seismological catalog as surface explosions by the seismo-acoustic analysis. Besides of the surface explosions, the network also detected infrasound signals from other sources, such as bolide, typhoons, rocket launches, and underground nuclear test occurred in and around the Korean Peninsula. In this study, ten years of seismo-acoustic data are reviewed with recent infrasonic detection algorithm and association method that finally linked to the seismic monitoring system of the KIGAM to increase the detection rate of surface explosions. We present the long-term results of seismo-acoustic analysis, the detection capability of the multiple arrays, and implications for seismic source location. Since the seismo-acoustic analysis is proved as a definite method to discriminate surface explosion, the analysis will be

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

    NASA Astrophysics Data System (ADS)

    Brochetti, Denise

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

  12. Acoustical and functional analysis of Mountain lion (Puma concolor) vocalizations

    NASA Astrophysics Data System (ADS)

    Potter, Jacquelyn

    2002-05-01

    A 2-year study resulted in acoustic analysis of the structure of over 900 mountain lion vocalizations recorded in a seminatural setting at Wildlife Prairie Park near Peoria, Illinois. A vocal repertoire was obtained by describing quantitative variables about the sounds, i.e., frequency of the dominant part of the sound (beginning, ending, maximum, and minimum), duration, and number of components. Other variables described the tonal, harmonic, and wideband qualities of the sounds. Behavioral data were collected during the same period. Further analysis of both acoustic and behavioral data was completed to develop a correlation matrix between vocalizations and behavior. This study also looked at the effects of seasons on vocal behavior. Correlations were found between vocalization types and rates of usage with specific behaviors. Vocalization type and the usage rate also varied by season.

  13. Frequency Analysis of Acoustic Emission - Application to machining and welding

    NASA Astrophysics Data System (ADS)

    Snoussi, A.

    1987-01-01

    Ultrasonic acoustic waves were seized and exploited within a bandwidth ranging from 30 kHz to 55 kHz for non-destructive control when boring three kinds of steel with a digitally programmed drill. In addition, these waves were considered in soldering two steels and one aluminum using T.I.G. process. Spectrum analysis of acoustic emissions produced during the drill is closely related to the extraction of turnings from the metal. Because of the wick's progressive wearing out, the spectrum tends to be close to the machine's own noise spectrum. Meanwhile in the soldering operation of test-tubes of 2 mm thickness, the frequency analysis shows a particular frequency called signature corresponding to the flow of protection gas. Other frequencies associated to some internal defects in the soldering process as a delay in the fissure and a lack in the fusion were detected.

  14. Fault diagnosis of reciprocating compressor valve with the method integrating acoustic emission signal and simulated valve motion

    NASA Astrophysics Data System (ADS)

    Wang, Yuefei; Xue, Chuang; Jia, Xiaohan; Peng, Xueyuan

    2015-05-01

    This paper proposes a method of diagnosing faults in reciprocating compressor valves using the acoustic emission signal coupled with the simulated valve motion. The actual working condition of a valve can be obtained by analyzing the acoustic emission signal in the crank angle domain and the valve movement can be predicted by simulating the valve motion. The exact opening and closing locations of a normal valve, provided by the simulated valve motion, can be used as references for the valve fault diagnosis. The typical valve faults are diagnosed to validate the feasibility and accuracy of the proposed method. The experimental results indicate that this method can easily distinguish the normal valve, valve flutter and valve delayed closing conditions. The characteristic locations of the opening and closing of the suction and discharge valves can be clearly identified in the waveform of the acoustic emission signal and the simulated valve motion.

  15. A methodology to condition distorted acoustic emission signals to identify fracture timing from human cadaver spine impact tests.

    PubMed

    Arun, Mike W J; Yoganandan, Narayan; Stemper, Brian D; Pintar, Frank A

    2014-12-01

    While studies have used acoustic sensors to determine fracture initiation time in biomechanical studies, a systematic procedure is not established to process acoustic signals. The objective of the study was to develop a methodology to condition distorted acoustic emission data using signal processing techniques to identify fracture initiation time. The methodology was developed from testing a human cadaver lumbar spine column. Acoustic sensors were glued to all vertebrae, high-rate impact loading was applied, load-time histories were recorded (load cell), and fracture was documented using CT. Compression fracture occurred to L1 while other vertebrae were intact. FFT of raw voltage-time traces were used to determine an optimum frequency range associated with high decibel levels. Signals were bandpass filtered in this range. Bursting pattern was found in the fractured vertebra while signals from other vertebrae were silent. Bursting time was associated with time of fracture initiation. Force at fracture was determined using this time and force-time data. The methodology is independent of selecting parameters a priori such as fixing a voltage level(s), bandpass frequency and/or using force-time signal, and allows determination of force based on time identified during signal processing. The methodology can be used for different body regions in cadaver experiments. PMID:25241279

  16. Voice-over: perceptual and acoustic analysis of vocal features.

    PubMed

    Medrado, Reny; Ferreira, Leslie Piccolotto; Behlau, Mara

    2005-09-01

    Voice-overs are professional voice users who use their voices to market products in the electronic media. The purposes of this study were to (1) analyze voice-overed and non-overed productions of an advertising text in two groups consisting of 10 male professional voice-overs and 10 male non-voice-overs; and (2) determine specific acoustic features of voice-over productions in both groups. A naïve group of listeners were engaged for the perceptual analysis of the recorded advertising text. The voice-overed production samples from both groups were submitted for analysis of acoustic and temporal features. The following parameters were analyzed: (1) the total text length, (2) the length of the three emphatic pauses, (3) values of the mean, (4) minimum, (5) maximum fundamental frequency, and (6) the semitone range. The majority of voice-overs and non-voice-overs were correctly identified by the listeners in both productions. However voice-overs were more consistently correctly identified than non-voice-overs. The total text length was greater for voice-overs. The pause time distribution was statistically more homogeneous for the voice-overs. The acoustic analysis indicated that the voice-overs had lower values of mean, minimum, and maximum fundamental frequency and a greater range of semitones. The voice-overs carry the voice-overed production features to their non-voice-overed production. PMID:16102662

  17. Wavenumber transform analysis for acoustic black hole design.

    PubMed

    Feurtado, Philip A; Conlon, Stephen C

    2016-07-01

    Acoustic black holes (ABHs) are effective, passive, lightweight vibration absorbers that have been developed and shown to effectively reduce the structural vibration and radiated sound of beam and plate structures. ABHs employ a local thickness change that reduces the speed of bending waves and increases the transverse vibration amplitude. The vibrational energy can then be effectively focused and dissipated by material losses or through conventional viscoelastic damping treatments. In this work, the measured vibratory response of embedded ABH plates was transformed into the wavenumber domain in order to investigate the use of wavenumber analysis for characterizing, designing, and optimizing practical ABH systems. The results showed that wavenumber transform analysis can be used to simultaneously visualize multiple aspects of ABH performance including changes in bending wave speed, transverse vibration amplitude, and energy dissipation. The analysis was also used to investigate the structural acoustic coupling of the ABH system and determine the radiation efficiency of the embedded ABH plates compared to a uniform plate. The results demonstrated that the ABH effect results in acoustic decoupling as well as vibration reduction. The wavenumber transform based methods and results will be useful for implementing ABHs into real world structures. PMID:27475193

  18. Acoustic emission from single point machining: Source mechanisms and signal changes with tool wear

    SciTech Connect

    Heiple, C.R.; Carpenter, S.H.; Armentrout, D.L.; McManigle, A.P.

    1994-05-01

    Acoustic emission (AE) was monitored during single point, continuous machining of 4340 steel and Ti-6Al-4V as a function of heat treatment. Heat treatments that increase the strength of 4340 steel substantially increase the amount of AE produced during deformation, while heat treatments that increase the strength of Ti-6Al-4V dramatically decrease the amount of AE produced during deformation. There was little change in root-mean-square (rms) AE level during machining for either alloy as a function of prior heat treatment, demonstrating that chip deformation is not a major source of AE in single point machining. Additional data from a variety of materials suggest that sliding friction between the nose and/or flank of the tool and the newly machined surface is the primary source of AE. Changes in AE signal characteristics with tool wear were also monitored during single point machining. No signal characteristic changed in the same way with tool wear for all materials tested. A single change in a particular AE signal characteristic with tool wear valid for all materials probably does not exist. Nevertheless, changes in various signal characteristics with wear for a given material may be sufficient to be used to monitor tool wear.

  19. Seismo-acoustic analysis for series of ammunition demolition explosions at Sayarim, Israel

    NASA Astrophysics Data System (ADS)

    Pinsky, V.; Gitterman, Y.; Ben-Horin, Y.; Arrowsmith, S.

    2012-04-01

    We analyzed detection and location capabilities of a seismo-acoustic network using records of explosion series conducted recently at Sayarim Military Range (SMR), Israel, for demolition of outdated ammunitions. The signals from the explosions have been recorded at local distances by the Israel Seismic Network (ISN), two single infrasound sensors co-located with ISN seismic stations and two infrasound arrays deployed by Israel NDC: 5-element IMA (at Mt. Meron), co-located with IMS seismic array MMAI, and 4-element test temporary array in Northern Negev. All shots (each one with nominal explosives weight ~10-15 tons, detonated simultaneously) were located at the same small area ~0.5x0.5 km, in some cases placed in several grooves, separated by 0.3-0.5 km. Some shots were divided in time by only 20-40 sec, facilitating analysis of the source variability under about constant atmospheric conditions. The following preliminary results have been obtained: 1) the accuracy of seismo-acoustic source location, provided by 5 seismic stations and 2 acoustic receivers using celerity model and wind profile for the day, was within ±1 km of the SMR explosion site; 2) the analysis of acoustic phases recorded at ISN seismic stations at different azimuths showed a clear correlation of the phase peak amplitude with the wind direction; 3) infrasound signals from the explosions were clearly detected at IMA array at 340 km, whereas seismic signals were attenuated below the background noise after 100-150 km; 4) the frequency band occupied by the signal is estimated within 0.2-5 Hz, and the f-k analysis, applied to the infrasound array recordings, provided azimuth of 184° and apparent velocity of 344 m/s, compared to the true azimuth 190° and celerity 277 m/s (the azimuth bias could be explained by the prevailing strong south-western winds ~80 knots observed at a time of the explosion at assumed propagation heights); 5) spectral analysis of infrasound signals provided determination of the

  20. Divergence of acoustic signals in a widely distributed frog: relevance of inter-male interactions.

    PubMed

    Velásquez, Nelson A; Opazo, Daniel; Díaz, Javier; Penna, Mario

    2014-01-01

    Divergence of acoustic signals in a geographic scale results from diverse evolutionary forces acting in parallel and affecting directly inter-male vocal interactions among disjunct populations. Pleurodema thaul is a frog having an extensive latitudinal distribution in Chile along which males' advertisement calls exhibit an important variation. Using the playback paradigm we studied the evoked vocal responses of males of three populations of P. thaul in Chile, from northern, central and southern distribution. In each population, males were stimulated with standard synthetic calls having the acoustic structure of local and foreign populations. Males of both northern and central populations displayed strong vocal responses when were confronted with the synthetic call of their own populations, giving weaker responses to the call of the southern population. The southern population gave stronger responses to calls of the northern population than to the local call. Furthermore, males in all populations were stimulated with synthetic calls for which the dominant frequency, pulse rate and modulation depth were varied parametrically. Individuals from the northern and central populations gave lower responses to a synthetic call devoid of amplitude modulation relative to stimuli containing modulation depths between 30-100%, whereas the southern population responded similarly to all stimuli in this series. Geographic variation in the evoked vocal responses of males of P. thaul underlines the importance of inter-male interactions in driving the divergence of the acoustic traits and contributes evidence for a role of intra-sexual selection in the evolution of the sound communication system of this anuran. PMID:24489957

  1. Linear Stability Analysis of an Acoustically Vaporized Droplet

    NASA Astrophysics Data System (ADS)

    Siddiqui, Junaid; Qamar, Adnan; Samtaney, Ravi

    2015-11-01

    Acoustic droplet vaporization (ADV) is a phase transition phenomena of a superheat liquid (Dodecafluoropentane, C5F12) droplet to a gaseous bubble, instigated by a high-intensity acoustic pulse. This approach was first studied in imaging applications, and applicable in several therapeutic areas such as gas embolotherapy, thrombus dissolution, and drug delivery. High-speed imaging and theoretical modeling of ADV has elucidated several physical aspects, ranging from bubble nucleation to its subsequent growth. Surface instabilities are known to exist and considered responsible for evolving bubble shapes (non-spherical growth, bubble splitting and bubble droplet encapsulation). We present a linear stability analysis of the dynamically evolving interfaces of an acoustically vaporized micro-droplet (liquid A) in an infinite pool of a second liquid (liquid B). We propose a thermal ADV model for the base state. The linear analysis utilizes spherical harmonics (Ynm, of degree m and order n) and under various physical assumptions results in a time-dependent ODE of the perturbed interface amplitudes (one at the vapor/liquid A interface and the other at the liquid A/liquid B interface). The perturbation amplitudes are found to grow exponentially and do not depend on m. Supported by KAUST Baseline Research Funds.

  2. Treated cabin acoustic prediction using statistical energy analysis

    NASA Technical Reports Server (NTRS)

    Yoerkie, Charles A.; Ingraham, Steven T.; Moore, James A.

    1987-01-01

    The application of statistical energy analysis (SEA) to the modeling and design of helicopter cabin interior noise control treatment is demonstrated. The information presented here is obtained from work sponsored at NASA Langley for the development of analytic modeling techniques and the basic understanding of cabin noise. Utility and executive interior models are developed directly from existing S-76 aircraft designs. The relative importance of panel transmission loss (TL), acoustic leakage, and absorption to the control of cabin noise is shown using the SEA modeling parameters. It is shown that the major cabin noise improvement below 1000 Hz comes from increased panel TL, while above 1000 Hz it comes from reduced acoustic leakage and increased absorption in the cabin and overhead cavities.

  3. Detection and processing of electromagnetic and near-field acoustic signals in elasmobranch fishes.

    PubMed Central

    Kalmijn, A D

    2000-01-01

    The acoustic near field of quietly moving underwater objects and the bio-electric field of aquatic animals exhibit great similarity, as both are predominantly governed by Laplace's equation. The acoustic and electrical sensory modalities thus may, in directing fishes to their prey, employ analogous processing algorithms, suggesting a common evolutionary design, founded on the salient physical features shared by the respective stimulus fields. Sharks and rays are capable of orientating to the earth's magnetic field and, hence, have a magnetic sense. The electromagnetic theory of orientation offers strong arguments for the animals using the electric fields induced by ocean currents and by their own motions in the earth's magnetic field. In the animal's frame of reference, in which the sense organs are at rest, the classical concept of motional electricity must be interpreted in relativistic terms. In the ampullae of Lorenzini, weak electric fields cause the ciliated apical receptor-cell membranes to produce graded, negative receptor currents opposite in direction to the fields applied. The observed currents form part of a positive-feedback mechanism, supporting the generation of receptor potentials much larger than the input signal. Acting across the basal cell membranes, the receptor potentials control the process of synaptic transmission. PMID:11079385

  4. Statistical Modeling of Large-Scale Signal Path Loss in Underwater Acoustic Networks

    PubMed Central

    Llor, Jesús; Malumbres, Manuel Perez

    2013-01-01

    In an underwater acoustic channel, the propagation conditions are known to vary in time, causing the deviation of the received signal strength from the nominal value predicted by a deterministic propagation model. To facilitate a large-scale system design in such conditions (e.g., power allocation), we have developed a statistical propagation model in which the transmission loss is treated as a random variable. By applying repetitive computation to the acoustic field, using ray tracing for a set of varying environmental conditions (surface height, wave activity, small node displacements around nominal locations, etc.), an ensemble of transmission losses is compiled and later used to infer the statistical model parameters. A reasonable agreement is found with log-normal distribution, whose mean obeys a log-distance increases, and whose variance appears to be constant for a certain range of inter-node distances in a given deployment location. The statistical model is deemed useful for higher-level system planning, where simulation is needed to assess the performance of candidate network protocols under various resource allocation policies, i.e., to determine the transmit power and bandwidth allocation necessary to achieve a desired level of performance (connectivity, throughput, reliability, etc.). PMID:23396190

  5. Can acoustic emissions patterns signal imminence of avalanche events in a growing sand pile?

    NASA Astrophysics Data System (ADS)

    Vögtli, Melanie; Lehmann, Peter; Breitenstein, Daniel; Or, Dani

    2014-05-01

    Gravity driven mass release is often triggered abruptly with limited precursory cues to indicate imminent failure and thus limiting early warning. Evidence suggests that with increased mechanical loading of a slope, numerous local damage events marking friction between rearranged particles or breakage of roots release strain energy as elastic waves measurable as acoustic emissions. We examined the potential predictability of mass release events from preceding acoustic emission (AE) signatures in a well-known and simple model system of a growing sand pile. We installed four AE-sensors within the core of a 30 cm (diameter) sand pile fed by a constant input of grains and mounted on a balance. Subsequent to the convergence of the slope to dynamic angle of repose, sand avalanche across the bottom boundary were monitored by abrupt mass change and by the amplitudes and number of AE events (recorded at high frequency and averaged to 0.2 s). We detected a systematic change of AE-patterns characterized by systematically decreasing AE standard deviation prior to each mass release. Although the lead time following minimum AE standard deviation was relatively short (10s of seconds), the AE signature already started to change minutes before the mass release. Accordingly the information embedded in AE signal dynamics could potentially offer larger lead times for systems of practical interest.

  6. Statistical modeling of large-scale signal path loss in underwater acoustic networks.

    PubMed

    Llor, Jesús; Malumbres, Manuel Perez

    2013-01-01

    In an underwater acoustic channel, the propagation conditions are known to vary in time, causing the deviation of the received signal strength from the nominal value predicted by a deterministic propagation model. To facilitate a large-scale system design in such conditions (e.g., power allocation), we have developed a statistical propagation model in which the transmission loss is treated as a random variable. By applying repetitive computation to the acoustic field, using ray tracing for a set of varying environmental conditions (surface height, wave activity, small node displacements around nominal locations, etc.), an ensemble of transmission losses is compiled and later used to infer the statistical model parameters. A reasonable agreement is found with log-normal distribution, whose mean obeys a log-distance increases, and whose variance appears to be constant for a certain range of inter-node distances in a given deployment location. The statistical model is deemed useful for higher-level system planning, where simulation is needed to assess the performance of candidate network protocols under various resource allocation policies, i.e., to determine the transmit power and bandwidth allocation necessary to achieve a desired level of performance (connectivity, throughput, reliability, etc.). PMID:23396190

  7. Method for simultaneously making a plurality of acoustic signal sensor elements

    NASA Technical Reports Server (NTRS)

    Bryant, Timothy D. (Inventor); Wynkoop, Mark W. (Inventor); Holloway, Nancy M. H. (Inventor); Zuckerwar, Allan J. (Inventor)

    2005-01-01

    A fetal heart monitoring system preferably comprising a backing plate having a generally concave front surface and a generally convex back surface, and at least one sensor element attached to the concave front surface for acquiring acoustic fetal heart signals produced by a fetus within a body. The sensor element has a shape that conforms to the generally concave back surface of the backing plate. In one embodiment, the at least one sensor element comprises an inner sensor, and a plurality of outer sensors surrounding the inner sensor. The fetal heart monitoring system can further comprise a web belt, and a web belt guide movably attached to the web belt. The web belt guide being is to the convex back surface of the backing plate.

  8. Acoustic signals generated in piezoelectric lead zirconate titanate elements by direct bombardment with xenon ions

    NASA Astrophysics Data System (ADS)

    Miyachi, T.; Nakamura, Y.; Kuraza, G.; Fujii, M.; Nagashima, A.; Hasebe, N.; Kobayashi, M. N.; Kobayashi, S.; Miyajima, M.; Mori, K.; Okudaira, O.; Yamashita, N.; Shibata, H.; Murakami, T.; Uchihori, Y.; Okada, N.

    2006-12-01

    Acoustic signals were observed with a lead-zirconate-titanate (PZT) element that was directly irradiated with a 368 MeV/n xenon beam. Using an array comprising PZT elements, the energy loss in the PZT was studied. These elements are sensitive to an energy deposit of 100 nJ. A series of values of output voltage vs. integrated thickness of PZT was represented along a line similar to the ionization loss calculated by the Bethe-Bloch formula. The induced voltage was attributed to several processes—ionization, thermal, elastic, and piezoelectric processes. This study describes the possible applications of the PZT element as an active medium for calorimeters and a monitor for hypervelocity impact of space dust.

  9. Multiplex transmission system for gate drive signals of inverter circuit using surface acoustic wave filters

    NASA Astrophysics Data System (ADS)

    Suzuki, Akifumi; Ueda, Kensuke; Goka, Shigeyoshi; Wada, Keiji; Kakio, Shoji

    2016-07-01

    We propose and fabricate a multiplexed transmission system based on frequency-division multiple access (FDMA) with surface acoustic wave (SAW) filters. SAW filters are suitable for use in wide-gap switching devices and multilevel inverters because of their capability to operate at high temperatures, good electrical isolation, low cost, and high reliability. Our proposed system reduces the number of electrical signal wires needed to control each switching device and eliminates the need for isolation circuits, simplifying the transmission system and gate drive circuits. We successfully controlled two switching devices with a single coaxial line and confirmed the operation of a single-phase half-bridge inverter at a supply voltage of 100 V, and the total delay time to control the switching devices was less than 2.5 µs. Our experimental results validated our proposed system.

  10. Evolution of the electron acoustic signal as function of doping level in III-V semiconductors

    SciTech Connect

    Bresse, J.F.; Papadopoulo, A.C.

    1988-07-01

    The evolution of the electron acoustic signal has been measured for Be- and Si-doped GaAs and Ga/sub 0.28/Al/sub 0.19/In/sub 0.53/As layers with doping levels from10/sup 17/ to 10/sup 20/ at. cm/sup -3/. The samples have also been analyzed by cathodoluminescence spectroscopy for near-band-edge transition and deep level emission. The results are explained by the reduction of the mean free path of phonons, giving rise to a lattice thermal conductivity decrease. Meanwhile, the electronic part of the thermal conductivity of these compounds is found to be nearly negligible.

  11. Precursory Acoustic Signals Detection in Rockfall Events by Means of Optical Fiber Sensors

    NASA Astrophysics Data System (ADS)

    Schenato, L.; Marcato, G.; Gruca, G.; Iannuzzi, D.; Palmieri, L.; Galtarossa, A.; Pasuto, A.

    2012-12-01

    Rockfalls represent a major source of hazard in mountain areas: they occur at the apex of a process of stress accumulation in the unstable slope, during which part of the accumulated energy is released in small internal cracks. These cracks and the related acoustic emissions (AE) can, therefore, be used as precursory signals, through which the unstable rock could be monitored. In particular, according to previous scientific literature AE can be monitored in the range 20÷100 kHz. With respect to traditional AE sensors, such as accelerometers and piezoelectric transducers, fiber optic sensors (FOSs) may provide a reliable solution, potentially offering more robustness to electromagnetic interference, smaller form factor, multiplexing ability and increased distance range and higher sensitivity. To explore this possibility, in this work we have experimentally analyzed two interferometric fiber optical sensors for AE detection in rock masses. In particular, the first sensor is made of 100 m of G.657 optical fiber, tightly wound on an aluminum flanged hollow mandrel (inner diameter 30 mm, height 42 mm) that is isolated from the environment with acoustic absorbing material. A 4-cm-long M10 screw, which acts also as the main mean of acoustic coupling between the rock and the sensor, is used to fasten the sensor to the rock. This fiber coil sensor (FCS) is inserted in the sensing arm of a fiber Mach-Zehnder interferometer. The second sensor consists in a micro cantilever carved on the top of a cylindrical silica ferrule, with a marked mechanical resonance at about 12.5 kHz (Q-factor of about 400). A standard single mode fiber is housed in the same ferrule and the gap between the cantilever and the fiber end face acts as a vibration-sensitive Fabry-Perot cavity, interrogated with a low-coherence laser, tuned at the quadrature point of the cavity. The sensor is housed in a 2-cm-long M10 bored bolt. Performance have been compared with those from a standard piezo

  12. Classifying acoustic signals into phoneme categories: average and dyslexic readers make use of complex dynamical patterns and multifractal scaling properties of the speech signal

    PubMed Central

    2015-01-01

    Several competing aetiologies of developmental dyslexia suggest that the problems with acquiring literacy skills are causally entailed by low-level auditory and/or speech perception processes. The purpose of this study is to evaluate the diverging claims about the specific deficient peceptual processes under conditions of strong inference. Theoretically relevant acoustic features were extracted from a set of artificial speech stimuli that lie on a /bAk/-/dAk/ continuum. The features were tested on their ability to enable a simple classifier (Quadratic Discriminant Analysis) to reproduce the observed classification performance of average and dyslexic readers in a speech perception experiment. The ‘classical’ features examined were based on component process accounts of developmental dyslexia such as the supposed deficit in Envelope Rise Time detection and the deficit in the detection of rapid changes in the distribution of energy in the frequency spectrum (formant transitions). Studies examining these temporal processing deficit hypotheses do not employ measures that quantify the temporal dynamics of stimuli. It is shown that measures based on quantification of the dynamics of complex, interaction-dominant systems (Recurrence Quantification Analysis and the multifractal spectrum) enable QDA to classify the stimuli almost identically as observed in dyslexic and average reading participants. It seems unlikely that participants used any of the features that are traditionally associated with accounts of (impaired) speech perception. The nature of the variables quantifying the temporal dynamics of the speech stimuli imply that the classification of speech stimuli cannot be regarded as a linear aggregate of component processes that each parse the acoustic signal independent of one another, as is assumed by the ‘classical’ aetiologies of developmental dyslexia. It is suggested that the results imply that the differences in speech perception performance between

  13. Classifying acoustic signals into phoneme categories: average and dyslexic readers make use of complex dynamical patterns and multifractal scaling properties of the speech signal.

    PubMed

    Hasselman, Fred

    2015-01-01

    Several competing aetiologies of developmental dyslexia suggest that the problems with acquiring literacy skills are causally entailed by low-level auditory and/or speech perception processes. The purpose of this study is to evaluate the diverging claims about the specific deficient peceptual processes under conditions of strong inference. Theoretically relevant acoustic features were extracted from a set of artificial speech stimuli that lie on a /bAk/-/dAk/ continuum. The features were tested on their ability to enable a simple classifier (Quadratic Discriminant Analysis) to reproduce the observed classification performance of average and dyslexic readers in a speech perception experiment. The 'classical' features examined were based on component process accounts of developmental dyslexia such as the supposed deficit in Envelope Rise Time detection and the deficit in the detection of rapid changes in the distribution of energy in the frequency spectrum (formant transitions). Studies examining these temporal processing deficit hypotheses do not employ measures that quantify the temporal dynamics of stimuli. It is shown that measures based on quantification of the dynamics of complex, interaction-dominant systems (Recurrence Quantification Analysis and the multifractal spectrum) enable QDA to classify the stimuli almost identically as observed in dyslexic and average reading participants. It seems unlikely that participants used any of the features that are traditionally associated with accounts of (impaired) speech perception. The nature of the variables quantifying the temporal dynamics of the speech stimuli imply that the classification of speech stimuli cannot be regarded as a linear aggregate of component processes that each parse the acoustic signal independent of one another, as is assumed by the 'classical' aetiologies of developmental dyslexia. It is suggested that the results imply that the differences in speech perception performance between average and

  14. [Acoustic analysis of the voice in singing children].

    PubMed

    Shilenkova, V V; Korotchenko, V V

    2010-01-01

    The present acoustic analysis of the voice is based on the data obtained from 54 singing children (19 boys and 25 girls). They were divided into two groups of 27 subjects each, with one including premutational-age the other mutational-age children (from 8 to 12 and from 13 to 16 years respectively). software package was used to analyse phonetograms and spectrograms of the voice and to study the speech profile. The acoustic parameters measured included voice frequency range, strength, and Jitter, maximum phonation time, and dysphonic index (DSI) depending on the age of the singing children. Premutational acoustic voice characteristics were essentially similar in boys and girls unlike mutational ones that differed dramatically, in the first place due to their substantial change in boys. The boys' voice underwent marked narrowing of the frequency range and its shift toward lower values, the jitter increased, and DSI became negative (-1.7+/-2.6). On the contrary, the voice frequency range in girls broadened and shifted toward both high and low frequencies; the girls showed only small amounts of Jitter and high DSI (2.4+/-2.2). PMID:20436424

  15. Acoustic signal propagation and measurement in natural stream channels for application to surrogate bed load measurements: Halfmoon Creek, Colorado.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Monitoring sediment-generated noise using submerged hydrophones is a surrogate method for measuring bed load transport in streams with the potential for improving estimates of bed load transport through widespread, inexpensive monitoring. Understanding acoustic signal propagation in natural stream e...

  16. EEG signal analysis: a survey.

    PubMed

    Subha, D Puthankattil; Joseph, Paul K; Acharya U, Rajendra; Lim, Choo Min

    2010-04-01

    The EEG (Electroencephalogram) signal indicates the electrical activity of the brain. They are highly random in nature and may contain useful information about the brain state. However, it is very difficult to get useful information from these signals directly in the time domain just by observing them. They are basically non-linear and nonstationary in nature. Hence, important features can be extracted for the diagnosis of different diseases using advanced signal processing techniques. In this paper the effect of different events on the EEG signal, and different signal processing methods used to extract the hidden information from the signal are discussed in detail. Linear, Frequency domain, time - frequency and non-linear techniques like correlation dimension (CD), largest Lyapunov exponent (LLE), Hurst exponent (H), different entropies, fractal dimension(FD), Higher Order Spectra (HOS), phase space plots and recurrence plots are discussed in detail using a typical normal EEG signal. PMID:20433058

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

    NASA Astrophysics Data System (ADS)

    Li, Dongsheng; Chen, Zhi

    2015-04-01

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

  18. Acoustical analysis and multiple source auralizations of charismatic worship spaces

    NASA Astrophysics Data System (ADS)

    Lee, Richard W.

    2001-05-01

    Because of the spontaneity and high level of call and response, many charismatic churches have verbal and musical communication problems that stem from highly reverberant sound fields, poor speech intelligibility, and muddy music. This research looks at the subjective dimensions of room acoustics perception that affect a charismatic worship space, which is summarized using the acronym RISCS (reverberation, intimacy, strength, coloration, and spaciousness). The method of research is to obtain acoustical measurements for three worship spaces in order to analyze the objective parameters associated with the RISCS subjective dimensions. For the same spaces, binaural room impulse response (BRIR) measurements are done for different receiver positions in order to create an auralization for each position. The subjective descriptors of RISCS are analyzed through the use of listening tests of the three auralized spaces. The results from the measurements and listening tests are analyzed to determine if listeners' perceptions correlate with the objective parameter results, the appropriateness of the subjective parameters for the use of the space, and which parameters seem to take precedent. A comparison of the multi-source auralization to a conventional single-source auralization was done with the mixed down version of the synchronized multi-track anechoic signals.

  19. Wing Morphometry and Acoustic Signals in Sterile and Wild Males: Implications for Mating Success in Ceratitis capitata

    PubMed Central

    de Souza, João Maria Gomes Alencar; Molina, Wagner Franco; de Almeida, Lúcia Maria; de Gouveia, Milson Bezerra; de Macêdo, Francisco Pepino; Laumann, Raul Alberto; Paranhos, Beatriz Aguiar Jordão

    2015-01-01

    The sterile insect technique (SIT) is widely utilized in the biological control of fruit flies of the family Tephritidae, particularly against the Mediterranean fruit fly. This study investigated the interaction between mating success and morphometric variation in the wings and the production of acoustic signals among three male groups of Ceratitis capitata (Wiedemann): (1) wild males, (2) irradiated with Co-60 (steriles), and (3) irradiated (steriles) and treated with ginger oil. The canonical variate analysis discriminated two groups (males irradiated and males wild), based on the morphological shape of the wings. Among males that emit buzz signals, wild males obtained copulation more frequently than males in Groups 2 and 3. The individuals of Group 3 achieved more matings than those in Group 2. Wild males displayed lower pulse duration, higher intervals between pulses, and higher dominant frequency. Regarding the reproductive success, the morphological differences in the wings' shape between accepted and nonaccepted males are higher in wild males than in the irradiated ones. The present results can be useful in programs using the sterile insect technique for biological control of C. capitata. PMID:26075293

  20. Wing Morphometry and Acoustic Signals in Sterile and Wild Males: Implications for Mating Success in Ceratitis capitata.

    PubMed

    de Souza, João Maria Gomes Alencar; de Lima-Filho, Paulo Augusto; Molina, Wagner Franco; de Almeida, Lúcia Maria; de Gouveia, Milson Bezerra; de Macêdo, Francisco Pepino; Laumann, Raul Alberto; Paranhos, Beatriz Aguiar Jordão

    2015-01-01

    The sterile insect technique (SIT) is widely utilized in the biological control of fruit flies of the family Tephritidae, particularly against the Mediterranean fruit fly. This study investigated the interaction between mating success and morphometric variation in the wings and the production of acoustic signals among three male groups of Ceratitis capitata (Wiedemann): (1) wild males, (2) irradiated with Co-60 (steriles), and (3) irradiated (steriles) and treated with ginger oil. The canonical variate analysis discriminated two groups (males irradiated and males wild), based on the morphological shape of the wings. Among males that emit buzz signals, wild males obtained copulation more frequently than males in Groups 2 and 3. The individuals of Group 3 achieved more matings than those in Group 2. Wild males displayed lower pulse duration, higher intervals between pulses, and higher dominant frequency. Regarding the reproductive success, the morphological differences in the wings' shape between accepted and nonaccepted males are higher in wild males than in the irradiated ones. The present results can be useful in programs using the sterile insect technique for biological control of C. capitata. PMID:26075293

  1. Alarm signals of the great gerbil: Acoustic variation by predator context, sex, age, individual, and family group

    NASA Astrophysics Data System (ADS)

    Randall, Jan A.; McCowan, Brenda; Collins, Kellie C.; Hooper, Stacie L.; Rogovin, Konstantin

    2005-10-01

    The great gerbil, Rhombomys opinus, is a highly social rodent that usually lives in family groups consisting of related females, their offspring, and an adult male. The gerbils emit alarm vocalizations in the presence of diverse predators with different hunting tactics. Alarm calls were recorded in response to three predators, a monitor lizard, hunting dog, and human, to determine whether the most common call type, the rhythmic call, is functionally referential with regard to type of predator. Results show variation in the alarm calls of both adults and subadults with the type of predator. Discriminant function analysis classified an average of 70% of calls to predator type. Call variation, however, was not limited to the predator context, because signal structure also differed by sex, age, individual callers, and family groups. These variations illustrate the flexibility of the rhythmic alarm call of the great gerbil and how it might have multiple functions and communicate in multiple contexts. Three alarm calls, variation in the rhythmic call, and vibrational signals generated from foot-drumming provide the gerbils with a varied and multi-channel acoustic repertoire.

  2. Statistical Signal Analysis for Systems with Interferenced Inputs

    NASA Technical Reports Server (NTRS)

    Bai, R. M.; Mielnicka-Pate, A. L.

    1985-01-01

    A new approach is introduced, based on statistical signal analysis, which overcomes the error due to input signal interference. The model analyzed is given. The input signals u sub 1 (t) and u sub 2 (t) are assumed to be unknown. The measurable signals x sub 1 (t) and x sub 2 (t) are interferened according to the frequency response functions, H sub 12 (f) and H sub 21 (f). The goal of the analysis was to evaluate the power output due to each input, u sub 1 (t) and u sub 2 (t), for the case where both are applied to the same time. In addition, all frequency response functions are calculated. The interferenced system is described by a set of five equations with six unknown functions. An IBM XT Personal Computer, which was interfaced with the FFT, was used to solve the set of equations. The software was tested on an electrical two-input, one-output system. The results were excellent. The research presented includes the analysis of the acoustic radiation from a rectangular plate with two force inputs and the sound pressure as an output signal.

  3. Phenotypic covariance structure and its divergence for acoustic mate attraction signals among four cricket species

    PubMed Central

    Bertram, Susan M; Fitzsimmons, Lauren P; McAuley, Emily M; Rundle, Howard D; Gorelick, Root

    2012-01-01

    The phenotypic variance–covariance matrix (P) describes the multivariate distribution of a population in phenotypic space, providing direct insight into the appropriateness of measured traits within the context of multicollinearity (i.e., do they describe any significant variance that is independent of other traits), and whether trait covariances restrict the combinations of phenotypes available to selection. Given the importance of P, it is therefore surprising that phenotypic covariances are seldom jointly analyzed and that the dimensionality of P has rarely been investigated in a rigorous statistical framework. Here, we used a repeated measures approach to quantify P separately for populations of four cricket species using seven acoustic signaling traits thought to enhance mate attraction. P was of full or almost full dimensionality in all four species, indicating that all traits conveyed some information that was independent of the other traits, and that phenotypic trait covariances do not constrain the combinations of signaling traits available to selection. P also differed significantly among species, although the dominant axis of phenotypic variation (pmax) was largely shared among three of the species (Acheta domesticus, Gryllus assimilis, G. texensis), but different in the fourth (G. veletis). In G. veletis and A. domesticus, but not G. assimilis and G. texensis, pmax was correlated with body size, while pmax was not correlated with residual mass (a condition measure) in any of the species. This study reveals the importance of jointly analyzing phenotypic traits. PMID:22408735

  4. Wintertime water dynamics and moonlight disruption of the acoustic backscatter diurnal signal in an ice-covered Northeast Greenland fjord

    NASA Astrophysics Data System (ADS)

    Petrusevich, Vladislav; Dmitrenko, Igor; Kirillov, Sergey; Rysgaard, Søren; Falk-Petersen, Stig; Barber, David; Ehn, Jens

    2016-04-01

    Six and a half month time series of acoustic backscatter and velocity from three ice-tethered Acoustic Doppler Current Profilers deployed in the Young Sound fjord in Northeast Greenland were used to analyse the acoustic signal. During period of civil polar night below the land-fast ice, the acoustic data suggest a systematic diel vertical migration (DVM) of backscatters likely comprised of zooplankton. The acoustic backscatter and vertical velocity data were also arranged in a form of actograms. Results show that the acoustic signal pattern typical to DVM in Young Sound persists throughout the entire winter including the period of civil polar night. However, polynya-enhanced estuarine-like cell circulation that occurred during winter disrupted the DVM signal favouring zooplankton to occupy the near-surface water layer. This suggests that zooplankton avoided spending additional energy crossing the interface with a relatively strong velocity gradient comprised by fjord inflow in the intermediate layer and outflow in the subsurface layer. Instead the zooplankton tended to favour remaining in the upper 40 m layer where also the relatively warmer water temperatures associated with upward heat flux during enhanced estuarine-like circulation could be energetically favourable. Furthermore, our data show moonlight disruption of DVM in the subsurface layer and weaker intensity of vertical migration beneath snow covered land-fast ice during polar night. Using existing models for lunar illuminance and light transmission through sea ice and snow cover we estimated under ice illuminance and compared it with known light sensitivity for Arctic zooplankton species.

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

    SciTech Connect

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

    2011-09-30

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

  6. a Psycholinguistic Model for Simultaneous Translation, and Proficiency Assessment by Automated Acoustic Analysis of Discourse.

    NASA Astrophysics Data System (ADS)

    Yaghi, Hussein M.

    Two separate but related issues are addressed: how simultaneous translation (ST) works on a cognitive level and how such translation can be objectively assessed. Both of these issues are discussed in the light of qualitative and quantitative analyses of a large corpus of recordings of ST and shadowing. The proposed ST model utilises knowledge derived from a discourse analysis of the data, many accepted facts in the psychology tradition, and evidence from controlled experiments that are carried out here. This model has three advantages: (i) it is based on analyses of extended spontaneous speech rather than word-, syllable-, or clause -bound stimuli; (ii) it draws equally on linguistic and psychological knowledge; and (iii) it adopts a non-traditional view of language called 'the linguistic construction of reality'. The discourse-based knowledge is also used to develop three computerised systems for the assessment of simultaneous translation: one is a semi-automated system that treats the content of the translation; and two are fully automated, one of which is based on the time structure of the acoustic signals whilst the other is based on their cross-correlation. For each system, several parameters of performance are identified, and they are correlated with assessments rendered by the traditional, subjective, qualitative method. Using signal processing techniques, the acoustic analysis of discourse leads to the conclusion that quality in simultaneous translation can be assessed quantitatively with varying degrees of automation. It identifies as measures of performance (i) three content-based standards; (ii) four time management parameters that reflect the influence of the source on the target language time structure; and (iii) two types of acoustical signal coherence. Proficiency in ST is shown to be directly related to coherence and speech rate but inversely related to omission and delay. High proficiency is associated with a high degree of simultaneity and

  7. Quantitative Analysis Of Acoustic Emission From Rock Fracture Experiments

    NASA Astrophysics Data System (ADS)

    Goodfellow, Sebastian David

    This thesis aims to advance the methods of quantitative acoustic emission (AE) analysis by calibrating sensors, characterizing sources, and applying the results to solve engi- neering problems. In the first part of this thesis, we built a calibration apparatus and successfully calibrated two commercial AE sensors. The ErgoTech sensor was found to have broadband velocity sensitivity and the Panametrics V103 was sensitive to surface normal displacement. These calibration results were applied to two AE data sets from rock fracture experiments in order to characterize the sources of AE events. The first data set was from an in situ rock fracture experiment conducted at the Underground Research Laboratory (URL). The Mine-By experiment was a large scale excavation response test where both AE (10 kHz - 1 MHz) and microseismicity (MS) (1 Hz - 10 kHz) were monitored. Using the calibration information, magnitude, stress drop, dimension and energy were successfully estimated for 21 AE events recorded in the tensile region of the tunnel wall. Magnitudes were in the range -7.5 < Mw < -6.8, which is consistent with other laboratory AE results, and stress drops were within the range commonly observed for induced seismicity in the field (0.1 - 10 MPa). The second data set was AE collected during a true-triaxial deformation experiment, where the objectives were to characterize laboratory AE sources and identify issues related to moving the analysis from ideal in situ conditions to more complex laboratory conditions in terms of the ability to conduct quantitative AE analysis. We found AE magnitudes in the range -7.8 < Mw < -6.7 and as with the in situ data, stress release was within the expected range of 0.1 - 10 MPa. We identified four major challenges to quantitative analysis in the laboratory, which in- hibited our ability to study parameter scaling (M0 ∝ fc -3 scaling). These challenges were 0c (1) limited knowledge of attenuation which we proved was continuously evolving, (2

  8. High Frequency Acoustic Response Characterization and Analysis of the Deep Throttling Common Extensible Cryogenic Engine

    NASA Technical Reports Server (NTRS)

    Casiano, M. J.

    2011-01-01

    The Common Extensive Cryogenic Engine program demonstrated the operation of a deep throttling engine design. The program, spanning five years from August 2005 to July 2010, funded testing through four separate engine demonstration test series. Along with successful completion of multiple objectives, a discrete response of approximately 4000 Hz was discovered and explored throughout the program. The typical low-amplitude acoustic response was evident in the chamber measurement through almost every operating condition; however, at certain off-nominal operating conditions, the response became discrete with higher amplitude. This paper summarizes the data reduction, characterization, and analysis of the 4,000 Hz response for the entire program duration, using the large amount of data collected. Upon first encountering the response, new objectives and instrumentation were incorporated in future test series to specifically collect 4,000 Hz data. The 4,000 Hz response was identified as being related to the first tangential acoustic mode by means of frequency estimation and spatial decomposition. The latter approach showed that the effective node line of the mode was aligned with the manifold propellant inlets with standing waves and quasi-standing waves present at various times. Contour maps that contain instantaneous frequency and amplitude trackings of the response were generated as a significant improvement to historical manual approaches of data reduction presentation. Signal analysis and dynamic data reduction also uncovered several other features of the response including a stable limit cycle, the progressive engagement of subsequent harmonics, the U-shaped time history, an intermittent response near the test-based neutral stability region, other acoustic modes, and indications of modulation with a separate subsynchronous response. Although no engine damage related to the acoustic mode was noted, the peak-to-peak fluctuating pressure amplitude achieved 12.1% of the

  9. Statistical Analysis of Acoustic Wave Parameters Near Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Rabello-Soares, M. Cristina; Bogart, Richard S.; Scherrer, Philip H.

    2016-08-01

    In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyze the differences in the parameters in magnetically quiet regions nearby an active region (which we call “nearby regions”), compared with those of quiet regions at the same disk locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring-diagram analysis of all active regions observed by the Helioseismic and Magnetic Imager (HMI) during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhacement (the “acoustic halo effect”) is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes from a deficit to an excess at around 4.2 mHz, but averages to zero over all modes. The frequency difference in nearby regions increases with increasing frequency until a point at which the frequency shifts turn over sharply, as in active regions. However, this turnover occurs around 4.9 mHz, which is significantly below the acoustic cutoff frequency. Inverting the horizontal flow parameters in the direction of the neigboring active regions, we find flows that are consistent with a model of the thermal energy flow being blocked directly below the active region.

  10. A perturbative analysis of surface acoustic wave propagation and reflection in interdigital transducers

    NASA Astrophysics Data System (ADS)

    Thoma, Carsten Hilmar

    1997-12-01

    The coupling of stress and strain fields to electric fields present in anisotropic piezoelectric crystals makes them ideal for use as electromechanical transducers in a wide variety of applications. In recent years such crystals have been utilized to produce surface acoustic wave devices for signal processing applications, in which an applied metallic grating both transmits and receives, through the piezoelectric effect, electromechanical surface waves. The design of such interdigital transducers requires an accurate knowledge of wave propagation and reflection. The presence of the metal grating in addition to its ideal transduction function, by means of electrical and mechanical loading, also introduces a velocity shift as well as reflection into substrate surface waves. We seek to obtain a consistent formulation of the wave behavior due to the electrical and mechanical loading of the substrate crystal by the metallic grating. A perturbative solution up to second order in h//lambda is developed, where h is the maximum grating height and λ the acoustic wavelength. For the operating frequencies and physical parameters of modern surface acoustic wave devices such an analysis will provide an adequate description of device behavior in many cases, thereby circumventing the need for more computationally laborious methods. Numerical calculations are presented and compared with available experimental data.

  11. Bioelectric signal analysis and measurement

    NASA Technical Reports Server (NTRS)

    Lai, D. C.

    1975-01-01

    Nonstationary time series techniques are used to analyze EEG signals for the estimation of alertness. A time varying order is extracted in sequential time series measurement of these data and strategies are devised for obtaining optimal representation of the EEG signal.

  12. Acoustic signal associated with the bursting of a soap film which initially closes an overpressurized cavity . Experiment and theory

    NASA Astrophysics Data System (ADS)

    Vidal, V.; Géminard, J.-C.; Divoux, T.; Melo, F.

    2006-12-01

    We report an experimental study of the sound produced by the bursting of a thin liquid film, which initially closes an overpressurized cylindrical cavity. There is a need for a deep understanding of the phenomenon, which can be very useful in numerous practical cases. For instance, in the nature, the volcanologists observe the bursting of large, elongated, gas-bubbles at the surface of lava lakes and record the associated sound emission. One can wonder which pieces of information they can get from such acoustic measurements. For a didactic purpose, we provide also the reader with all the theoretical background necessary for the understanding of the physical processes that govern the various characteristics of the acoustic signals: the cavity geometry governs the frequency; the viscous dissipation and the radiation are responsible for the damping; the acoustic energy informs about the characteristic time associated with the film-rupture more than about the energy initially loaded in the cavity.

  13. Analysis of Vibration and Acoustic Noise in Permanent Magnet Motors.

    NASA Astrophysics Data System (ADS)

    Hwang, Sangmoon

    The drive motor is a frequent source of vibration and acoustic noise in many precision spindle motors. One of the electromagnetic sources of vibration in permanent magnet motors is the torque ripple, consisting of the reluctance torque and electromagnetic torque fluctuation. This type of vibration is becoming more serious with the advent of new high-grade magnets with increased flux density. Acoustic noise of electromagnetic origin is difficult to predict and its exact mechanism is unclear. The mechanism of noise generation should be revealed to design a quieter motor which is the modern customer's demand. For motor operation at low speeds and loads, torque ripple due to the reluctance torque is often a source of vibration and control difficulty. The reluctance torque in a motor was calculated from the flux density by a finite element method and the Maxwell stress method. Effects of design parameters, such as stator slot width, permanent slot width, airgap length and magnetization direction, were investigated. Magnet pole shaping, by gradually decreasing the magnet thickness toward edges, yields a sinusoidal shape of the reluctance torque with reduced harmonics, thus reducing the vibration. This dissertation also presents two motor design techniques: stator tooth notching and rotor pole skewing with magnet pole shaping, and the effect of each method on the output torque. The analysis shows that the reluctance torque can be nearly eliminated by the suggested designs, with minimal sacrifice of the output torque. In permanent magnet DC motors, the most popular design type is the trapezoidal back electro-motive force (BEMF), for switched DC controllers. It is demonstrated that the output torque profile of one phase energized is qualitatively equivalent to the BEMF profile for motors with reduced reluctance torque. It implies that design of BEMF profile is possible by magnetic modeling of a motor, without expensive and time-consuming experiments for different designs

  14. Multi-dimensional analysis of subjective acoustical ratings and acoustical measures in existing concert halls

    NASA Astrophysics Data System (ADS)

    Okano, Toshiyuki

    2001-05-01

    Correlations between subjective acoustical ratings and hall-averaged values of acoustical measures are studied among existing worldwide major concert halls. It was shown that the classified acoustical ratings by Beranek [Concert and Opera Halls, How They Sound (ASA, 1996)] are discriminated correctly by combining binaural quality index (BQI) with some other acoustical measures. BQI is determined by the arithmetic average of inter-aural cross correlation coefficient in three octave bands of 500, 1000, and 2000 Hz, subtracted from unity, calculated from the early 80-ms part of binaural impulse response. Considering that the upper limit value of BQI not to cause disturbing image shift is approximately 0.85 at individual seat [Okano, J. Acoust. Soc. Am. 2219-2230 (2000)], the values of 0.6 or higher in hall averaged value of BQI, 0.85 or smaller in individual seat value of BQI, and approximately 5 dB or higher in strength factor at middle frequencies are proposed as design objectives to attain a high acoustical quality. It should be provided that other acoustical measures are also optimized. These target values will be very effective in studying room shape of halls, using scale models or computer models.

  15. Flow Visualization and Acoustic Signal Detection in the Process of Drop Impact on the Surface of a Liquid

    NASA Astrophysics Data System (ADS)

    Prohorov, V. E.

    2012-04-01

    An experimental study of hydrophysical and acoustic phenomena produced by drop falling on the free water surface is of great practical importance with regard to rain intensity measurement and preparation of oceanic acoustic noises model. Key features of underwater flow associated with an acoustic emission can be revealed in the laboratory experiments under controllable reproducible conditions. The current paper describes the experiments in which the drops detach from a nozzle of 0.4 cm in diameter. The flows impact area is visualized by high speed video camera CR3000×2 whose frame rate varies from 4000 to 20000 fps. Acoustic signals are measured by calibrated hydrophone (bandpass from 2 Hz to 125 kHz) which is synchronized with the video camera by means of special PC interface supplied with multichannel 12-bit AD-convertor. The accuracy of synchronization is supported on the levels 1 µS. The total acoustic signal produced by drop consists of the initial (impact) pulse followed by one or more resonant sound packets emitted by air bubbles separating from the underwater cavity. Maximal number of packets fixed in the experiments is 4. Comparison of the video- and acoustic data show that resonant packets radiation is strongly timed to the moments of detachment of the air cavity from the underwater cavern formed in the process of absorption of the drop by intaking liquid. The detachment is followed by extremely high accelerations of the underwater cavity tip when it tears off the basic cavern. Acceleration is estimated at level 1000 m/S that matches pressure gradient jump initiated by accelerations is of an order of 10 Pa/m. Detached cavity is initially of irregular form but then turns to regular (elliptic or spherical) shape within some period during which the sound packet is emitted. The work is supported by Ministry of Education and Science RF (Goscontract No. 16.518.11.7059).

  16. Signal processing Model/Method for Recovering Acoustic Reflectivity of Spot Weld

    2005-09-08

    empirically. For fast estimation of R using only observations beta(1, ..., T) a receiver state equation has been derived, and is attached as Eq. (3). This equation has the further advantage that the initial impulse S need not be known, rather it is estimated simultaneously. This is necessary because element failure and coupling can cause large variations in S. Constrained nonlinear least squares techniques can be applied to this equation to recover reflectivity (and initial impulse) [4]. In particular, the Gauss-Newton algorithm on the log of the sum of squared errors based on the receiver state equation is recommended. To summarize, it is the model described in Eqs. (2) and (3) that is novel, and that enables the recovery of acoustic reflectivity from the ultrasound signals. It has been verified that this reflectivity estimate provides a better indicator of weld veracity than other features previously derived from such signals.« less

  17. Principle component analysis for radiotracer signal separation.

    PubMed

    Kasban, H; Arafa, H; Elaraby, S M S

    2016-06-01

    Radiotracers can be used in several industrial applications by injecting the radiotracer into the industrial system and monitoring the radiation using radiation detectors for obtaining signals. These signals are analyzed to obtain indications about what is happening within the system or to determine the problems that may be present in the system. For multi-phase system analysis, more than one radiotracer is used and the result is a mixture of radiotracers signals. The problem is in such cases is how to separate these signals from each other. The paper presents a proposed method based on Principle Component Analysis (PCA) for separating mixed two radiotracer signals from each other. Two different radiotracers (Technetium-99m (Tc(99m)) and Barium-137m (Ba(137m))) were injected into a physical model for simulation of chemical reactor (PMSCR-MK2) for obtaining the radiotracer signals using radiation detectors and Data Acquisition System (DAS). The radiotracer signals are mixed and signal processing steps are performed include background correction and signal de-noising, then applying the signal separation algorithms. Three separation algorithms have been carried out; time domain based separation algorithm, Independent Component Analysis (ICA) based separation algorithm, and Principal Components Analysis (PCA) based separation algorithm. The results proved the superiority of the PCA based separation algorithm to the other based separation algorithm, and PCA based separation algorithm and the signal processing steps gives a considerable improvement of the separation process. PMID:26974488

  18. Acoustic streaming jets: A scaling and dimensional analysis

    SciTech Connect

    Botton, V. Henry, D.; Millet, S.; Ben-Hadid, H.; Garandet, J. P.

    2015-10-28

    We present our work on acoustic streaming free jets driven by ultrasonic beams in liquids. These jets are steady flows generated far from walls by progressive acoustic waves. As can be seen on figure 1, our set-up, denominated AStrID for Acoustic Streaming Investigation Device, is made of a water tank in which a 29 mm plane source emits continuous ultrasonic waves at typically 2 MHz. Our approach combines an experimental characterization of both the acoustic pressure field (hydrophone) and the obtained acoustic streaming velocity field (PIV visualization) on one hand, with CFD using an incompressible Navier-Stokes solver on the other hand.

  19. An electromagnetic finite difference time domain analog treatment of small signal acoustic interactions

    NASA Astrophysics Data System (ADS)

    Kunz, K.; Steich, D.; Lewis, K.; Landrum, C.; Barth, M.

    1994-03-01

    Hyperbolic partial differential equations encompass an extremely important set of physical phenomena including electromagnetics and acoustics. Small amplitude acoustic interactions behave much the same as electromagnetic interactions for longitudinal acoustic waves because of the similar nature of the governing hyperbolic equations. Differences appear when transverse acoustic waves are considered; nonetheless, the strong analogy between the acoustic and electromagnetic phenomena prompted the development of a Finite Difference Time Domain (FDTD) acoustic analog to the existing electromagnetic FDTD technique. The advantages of an acoustic FDTD (AFDTD) code are as follows: (1) boundary condition-free treatment of the acoustic scatterer--only the intrinsic properties of the scatterer's material are needed, no shell treatment or other set of special equations describing the macroscopic behavior of a sheet of material or a junction, etc. are required; this allows completely general geometries and materials in the model. (2) Advanced outer radiation boundary condition analogs--in the electromagnetics arena, highly absorbing outer radiation boundary conditions were developed that can be applied with little modification to the acoustics arena with equal success. (3) A suite of preexisting capabilities related to electromagnetic modeling--this includes automated model generation and interaction visualization as its most important components and is best exemplified by the capabilities of the LLNL generated TSAR electromagnetic FDTD code.

  20. Wavelet analysis of baryon acoustic structures in the galaxy distribution

    NASA Astrophysics Data System (ADS)

    Arnalte-Mur, P.; Labatie, A.; Clerc, N.; Martínez, V. J.; Starck, J.-L.; Lachièze-Rey, M.; Saar, E.; Paredes, S.

    2012-06-01

    Context. Baryon acoustic oscillations (BAO) are imprinted in the density field by acoustic waves travelling in the plasma of the early universe. Their fixed scale can be used as a standard ruler to study the geometry of the universe. Aims: The BAO have been previously detected using correlation functions and power spectra of the galaxy distribution. We present a new method to detect the real-space structures associated with BAO. These baryon acoustic structures are spherical shells of relatively small density contrast, surrounding high density central regions. Methods: We design a specific wavelet adapted to search for shells, and exploit the physics of the process by making use of two different mass tracers, introducing a specific statistic to detect the BAO features. We show the effect of the BAO signal in this new statistic when applied to the Λ - cold dark matter (ΛCDM) model, using an analytical approximation to the transfer function. We confirm the reliability and stability of our method by using cosmological N-body simulations from the MareNostrum Institut de Ciències de l'Espai (MICE). Results: We apply our method to the detection of BAO in a galaxy sample drawn from the Sloan Digital Sky Survey (SDSS). We use the "main" catalogue to trace the shells, and the luminous red galaxies (LRG) as tracers of the high density central regions. Using this new method, we detect, with a high significance, that the LRG in our sample are preferentially located close to the centres of shell-like structures in the density field, with characteristics similar to those expected from BAO. We show that stacking selected shells, we can find their characteristic density profile. Conclusions: We delineate a new feature of the cosmic web, the BAO shells. As these are real spatial structures, the BAO phenomenon can be studied in detail by examining those shells. Full Table 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc

  1. Coefficient of variation spectral analysis: An application to underwater acoustics

    NASA Astrophysics Data System (ADS)

    Herstein, P. D.; Laplante, R. F.

    1983-05-01

    Acoustic noise in the ocean is often described in terms of its power spectral density. Just as in other media, this noise consists of both narrowband and broadband frequency components. A major problem in the analysis of power spectral density measurements is distinguishing between narrowband spectral components of interest and contaminating narrowband components. In this paper, the use of coefficient of variation (Cv) spectrum is examined as an adjunct to the conventional power spectrum to distinguish narrowband components of interest from contaminating components. The theory of the Cv is presented. Coefficients for several classical input distributions are developed. It is shown that Cv spectra can be easily implemented as an adjunct procedure during the computation of the ensemble of averaged power spectra. Power and Cv spectra derived from actual at-sea sonobuoy measurements of deep ocean ambient noise separate narrowband components from narrowband lines of interest in the ensemble of averaged power spectra, these acoustic components of interest can be distinguished in the Cv spectra.

  2. An analysis of the acoustic input impedance of the ear.

    PubMed

    Withnell, Robert H; Gowdy, Lauren E

    2013-10-01

    Ear canal acoustics was examined using a one-dimensional lossy transmission line with a distributed load impedance to model the ear. The acoustic input impedance of the ear was derived from sound pressure measurements in the ear canal of healthy human ears. A nonlinear least squares fit of the model to data generated estimates for ear canal radius, ear canal length, and quantified the resistance that would produce transmission losses. Derivation of ear canal radius has application to quantifying the impedance mismatch at the eardrum between the ear canal and the middle ear. The length of the ear canal was found, in general, to be longer than the length derived from the one-quarter wavelength standing wave frequency, consistent with the middle ear being mass-controlled at the standing wave frequency. Viscothermal losses in the ear canal, in some cases, may exceed that attributable to a smooth rigid wall. Resistance in the middle ear was found to contribute significantly to the total resistance. In effect, this analysis "reverse engineers" physical parameters of the ear from sound pressure measurements in the ear canal. PMID:23917695

  3. Acoustic signal characteristic detection by neurons in ventral nucleus of the lateral lemniscus in mice

    PubMed Central

    LIU, Hui-Hua; HUANG, Cai-Fei; WANG, Xin

    2014-01-01

    Under free field conditions, we used single unit extracellular recording to study the detection of acoustic signals by neurons in the ventral nucleus of the lateral lemniscus (VNLL) in Kunming mouse (Mus musculus). The results indicate two types of firing patterns in VNLL neurons: onset and sustained. The first spike latency (FSL) of onset neurons was shorter than that of sustained neurons. With increasing sound intensity, the FSL of onset neurons remained stable and that of sustained neurons was shortened, indicating that onset neurons are characterized by precise timing. By comparing the values of Q10 and Q30 of the frequency tuning curve, no differences between onset and sustained neurons were found, suggesting that firing pattern and frequency tuning are not correlated. Among the three types of rate-intensity function (RIF) found in VNLL neurons, the proportion of monotonic RIF is the largest, followed by saturated RIF, and non-monotonic RIF. The dynamic range (DR) in onset neurons was shorter than in sustained neurons, indicating different capabilities in intensity tuning of different firing patterns and that these differences are correlated with the type of RIF. Our results also show that the best frequency of VNLL neurons was negatively correlated with depth, supporting the view point that the VNLL has frequency topologic organization. PMID:25465088

  4. Underwater acoustic communication using orthogonal signal division multiplexing scheme with time diversity

    NASA Astrophysics Data System (ADS)

    Ebihara, Tadashi; Ogasawara, Hanako; Mizutani, Koichi

    2016-03-01

    In this paper, an underwater acoustic (UWA) communication scheme for mobile platforms is proposed. The proposed scheme is based on the orthogonal signal division multiplexing (OSDM) scheme, which offers highly reliable UWA communication. However, OSDM is not suitable for mobile platforms as it is — it requires a receiver array and a large calculation cost for equalization. To establish a reliable link with small communication platforms, we design OSDM that can perform reliable communication without the need for an array and can reduce receiver complexity using the time-diversity technique (TD), and evaluate its performance in experiments. The experimental results suggest that OSDM-TD can simultaneously achieve power-efficient communications and receiver complexity reduction, and can realize small-scale communication platforms. In detail, OSDM-TD achieved almost the same communication quality as conventional OSDM, in exchange for an effective data rate. Moreover, the power efficiency of OSDM-TD was almost the same as that of conventional OSDM with two receiver array elements, although the calculation cost of OSDM-TD was far below that of conventional OSDM. As a result, it was found that OSDM-TD is suitable for UWA communication for mobile nodes whose capacity and computational resources are severely limited.

  5. Digital seismo-acoustic signal processing aboard a wireless sensor platform

    NASA Astrophysics Data System (ADS)

    Marcillo, O.; Johnson, J. B.; Lorincz, K.; Werner-Allen, G.; Welsh, M.

    2006-12-01

    We are developing a low power, low-cost wireless sensor array to conduct real-time signal processing of earthquakes at active volcanoes. The sensor array, which integrates data from both seismic and acoustic sensors, is based on Moteiv TMote Sky wireless sensor nodes (www.moteiv.com). The nodes feature a Texas Instruments MSP430 microcontroller, 48 Kbytes of program memory, 10 Kbytes of static RAM, 1 Mbyte of external flash memory, and a 2.4-GHz Chipcon CC2420 IEEE 802.15.4 radio. The TMote Sky is programmed in TinyOS. Basic signal processing occurs on an array of three peripheral sensor nodes. These nodes are tied into a dedicated GPS receiver node, which is focused on time synchronization, and a central communications node, which handles data integration and additional processing. The sensor nodes incorporate dual 12-bit digitizers sampling a seismic sensor and a pressure transducer at 100 samples per second. The wireless capabilities of the system allow flexible array geometry, with a maximum aperture of 200m. We have already developed the digital signal processing routines on board the Moteiv Tmote sensor nodes. The developed routines accomplish Real-time Seismic-Amplitude Measurement (RSAM), Seismic Spectral- Amplitude Measurement (SSAM), and a user-configured Short Term Averaging / Long Term Averaging (STA LTA ratio), which is used to calculate first arrivals. The processed data from individual nodes are transmitted back to a central node, where additional processing may be performed. Such processing will include back azimuth determination and other wave field analyses. Future on-board signal processing will focus on event characterization utilizing pattern recognition and spectral characterization. The processed data is intended as low bandwidth information which can be transmitted periodically and at low cost through satellite telemetry to a web server. The processing is limited by the computational capabilities (RAM, ROM) of the nodes. Nevertheless, we

  6. Maintaining acoustic communication at a cocktail party: heterospecific masking noise improves signal detection through frequency separation

    PubMed Central

    Siegert, M. E.; Römer, H.; Hartbauer, M.

    2014-01-01

    SUMMARY We examined acoustic masking in a chirping katydid species of the Mecopoda elongata complex due to interference with a sympatric Mecopoda species where males produce continuous trills at high amplitudes. Frequency spectra of both calling songs range from 1 to 80 kHz; the chirper species has more energy in a narrow frequency band at 2 kHz and above 40 kHz. Behaviourally, chirper males successfully phase-locked their chirps to playbacks of conspecific chirps under masking conditions at signal-to-noise ratios (SNRs) of −8 dB. After the 2 kHz band in the chirp had been equalised to the level in the masking trill, the breakdown of phase-locked synchrony occurred at a SNR of +7 dB. The remarkable receiver performance is partially mirrored in the selective response of a first-order auditory interneuron (TN1) to conspecific chirps under these masking conditions. However, the selective response is only maintained for a stimulus including the 2 kHz component, although this frequency band has no influence on the unmasked TN1 response. Remarkably, the addition of masking noise at 65 dB sound pressure level (SPL) to threshold response levels of TN1 for pure tones of 2 kHz enhanced the sensitivity of the response by 10 dB. Thus, the spectral dissimilarity between masker and signal at a rather low frequency appears to be of crucial importance for the ability of the chirping species to communicate under strong masking by the trilling species. We discuss the possible properties underlying the cellular/synaptic mechanisms of the ‘novelty detector’. PMID:24307713

  7. Plant acoustics: in the search of a sound mechanism for sound signaling in plants.

    PubMed

    Mishra, Ratnesh Chandra; Ghosh, Ritesh; Bae, Hanhong

    2016-08-01

    Being sessile, plants continuously deal with their dynamic and complex surroundings, identifying important cues and reacting with appropriate responses. Consequently, the sensitivity of plants has evolved to perceive a myriad of external stimuli, which ultimately ensures their successful survival. Research over past centuries has established that plants respond to environmental factors such as light, temperature, moisture, and mechanical perturbations (e.g. wind, rain, touch, etc.) by suitably modulating their growth and development. However, sound vibrations (SVs) as a stimulus have only started receiving attention relatively recently. SVs have been shown to increase the yields of several crops and strengthen plant immunity against pathogens. These vibrations can also prime the plants so as to make them more tolerant to impending drought. Plants can recognize the chewing sounds of insect larvae and the buzz of a pollinating bee, and respond accordingly. It is thus plausible that SVs may serve as a long-range stimulus that evokes ecologically relevant signaling mechanisms in plants. Studies have suggested that SVs increase the transcription of certain genes, soluble protein content, and support enhanced growth and development in plants. At the cellular level, SVs can change the secondary structure of plasma membrane proteins, affect microfilament rearrangements, produce Ca(2+) signatures, cause increases in protein kinases, protective enzymes, peroxidases, antioxidant enzymes, amylase, H(+)-ATPase / K(+) channel activities, and enhance levels of polyamines, soluble sugars and auxin. In this paper, we propose a signaling model to account for the molecular episodes that SVs induce within the cell, and in so doing we uncover a number of interesting questions that need to be addressed by future research in plant acoustics. PMID:27342223

  8. Intelligent signal analysis and recognition

    NASA Technical Reports Server (NTRS)

    Levinson, Robert; Helman, Daniel; Oswalt, Edward

    1987-01-01

    Progress in the research and development of self-organizing database system that can support the identification and characterization of signals in an RF environment is described. As the radio frequency spectrum becomes more crowded, there are a number of situations that require a characterization of the RF environment. This database system is designed to be practical in applications where communications and other instruments encounter a time varying and complex RF environment. The primary application of this system is the guidance and control of NASA's SETI Microwave Observing Project. Other possible applications include selection of telemety bands for communication with spacecraft, and the scheduling of antenna for radio astronomy are two examples where characterization of the RF environment is required. In these applications, the RF environment is constantly changing, and even experienced operators cannot quickly identify the multitude of signals that can be encountered. Some of these signals are repetitive, others appear to occur sporadically.

  9. A Novel Analysis of Acoustic Oscillations in Chromospheric Active Regions

    NASA Astrophysics Data System (ADS)

    Monsue, Teresa; Hill, Frank; Stassun, Keivan G.

    2015-04-01

    A helioseismic analysis of the chromosphere is employed in H-alpha to study how solar flares around active regions affect the behavior of acoustic oscillations. Our analysis deals with flares directly over sunspots, where the region is highly magnetized. In our current study of analyzing these oscillations in the chromosphere we study the temporal evolution of the oscillatory behavior from data taken from the Global Oscillation Network Group (GONG) H-alpha detectors. We investigate the wave behavior across different frequency bands (1 < ν < 8.33 mHz). In order to analyze the frequency bands of the oscillations, our analysis utilizes time series data to create Fourier power spectra of individual pixels spatially resolved and temporally evolved around the flare region; thereby creating a movie of each frequency band. This study entails three active regions, directly over sunspots, in which flaring activity is taking place from two solar flares, which occurred on June 13th and July 12th, 2012. We found that the intensity of the flare has an effect on the oscillations within different frequency bands. A suppression of power was observed in dark anomalous structures across the total frequency bands and in other regions there was an observed boost in power due to flaring activity. We find that, in the heart of all three regions, the low-frequency power (˜1-2 mHz) is substantially enhanced immediately prior to and after the flare, and that power at all frequencies up to 8 mHz is depleted at flare maximum. This depletion is both frequency and time dependent, which probably reflects the changing depths visible during the flare in the bandpass of the filter. These variations are not observed outside the flaring region. The depletion may indicate that acoustic energy is being converted into thermal energy at flare maximum, while the low-frequency enhancement may arise from an instability in the chromosphere and provide an early warning of the flare onset.

  10. Independent component analysis of parameterized ECG signals.

    PubMed

    Tanskanen, Jarno M A; Viik, Jari J; Hyttinen, Jari A K

    2006-01-01

    Independent component analysis (ICA) of measured signals yields the independent sources, given certain fulfilled requirements. Properly parameterized signals provide a better view to the considered system aspects, while reducing the amount of data. It is little acknowledged that appropriately parameterized signals may be subjected to ICA, yielding independent components (ICs) displaying more clearly the investigated properties of the sources. In this paper, we propose ICA of parameterized signals, and demonstrate the concept with ICA of ST and R parameterizations of electrocardiogram (ECG) signals from ECG exercise test measurements from two coronary artery disease (CAD) patients. PMID:17945912

  11. Hilbert-Huang transformation-based time-frequency analysis methods in biomedical signal applications.

    PubMed

    Lin, Chin-Feng; Zhu, Jin-De

    2012-03-01

    Hilbert-Huang transformation, wavelet transformation, and Fourier transformation are the principal time-frequency analysis methods. These transformations can be used to discuss the frequency characteristics of linear and stationary signals, the time-frequency features of linear and non-stationary signals, the time-frequency features of non-linear and non-stationary signals, respectively. The Hilbert-Huang transformation is a combination of empirical mode decomposition and Hilbert spectral analysis. The empirical mode decomposition uses the characteristics of signals to adaptively decompose them to several intrinsic mode functions. Hilbert transforms are then used to transform the intrinsic mode functions into instantaneous frequencies, to obtain the signal's time-frequency-energy distributions and features. Hilbert-Huang transformation-based time-frequency analysis can be applied to natural physical signals such as earthquake waves, winds, ocean acoustic signals, mechanical diagnosis signals, and biomedical signals. In previous studies, we examined Hilbert-Huang transformation-based time-frequency analysis of the electroencephalogram FPI signals of clinical alcoholics, and 'sharp I' wave-based Hilbert-Huang transformation time-frequency features. In this paper, we discuss the application of Hilbert-Huang transformation-based time-frequency analysis to biomedical signals, such as electroencephalogram, electrocardiogram signals, electrogastrogram recordings, and speech signals. PMID:22558835

  12. Decomposition of frequency characteristics of acoustic emission signals for different types of partial discharges sources

    NASA Astrophysics Data System (ADS)

    Witos, F.; Gacek, Z.; Paduch, P.

    2006-11-01

    The problem touched in the article is decomposition of frequency characteristic of AE signals into elementary form of three-parametrical Gauss function. At the first stage, for modelled curves in form of sum of three-parametrical Gauss peaks, accordance of modelled curve and a curve resulting from a solutions obtained using method with dynamic windows, Levenberg-Marquardt algorithm, genetic algorithms and differential evolution algorithm are discussed. It is founded that analyses carried out by means differential evolution algorithm are effective and the computer system served an analysis of AE signal frequency characteristics was constructed. Decomposition of frequency characteristics for selected AE signals coming from modelled PD sources using different ends of the bushing, and real PD sources in generator coil bars are carried out.

  13. Considerations on nonlinearity measurement with high signal-to-noise ratio for RF surface and bulk acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Kodaira, Ryosuke; Omori, Tatsuya; Hashimoto, Ken-ya; Kyoya, Haruki; Nakagawa, Ryo

    2015-07-01

    This paper discusses the measurement setup of non-linearity caused in radio frequency (RF) surface and bulk acoustic wave (SAW/BAW) devices with high signal-to-noise ratio (SNR). It is shown that when some important points are considered, the background level can be suppressed better than -135 dBm, and the non-linearity signals can be measured in high SNR. Finally, measured results are compared with those measured independently by Murata Manufacturing, and validity of the measurement is cross-checked.

  14. Data Transmission Signal Design and Analysis

    NASA Technical Reports Server (NTRS)

    Moore, J. D.

    1972-01-01

    The error performances of several digital signaling methods are determined as a function of a specified signal-to-noise ratio. Results are obtained for Gaussian noise and impulse noise. Performance of a receiver for differentially encoded biphase signaling is obtained by extending the results of differential phase shift keying. The analysis presented obtains a closed-form answer through the use of some simplifying assumptions. The results give an insight into the analysis problem, however, the actual error performance may show a degradation because of the assumptions made in the analysis. Bipolar signaling decision-threshold selection is investigated. The optimum threshold depends on the signal-to-noise ratio and requires the use of an adaptive receiver.

  15. Site effect determination using seismic noise from Tungurahua volcano (Ecuador): implications for seismo-acoustic analysis

    NASA Astrophysics Data System (ADS)

    Palacios, Pablo; Kendall, J.-Michael; Mader, Heidy

    2015-05-01

    Scattering and refractions that occur in the heterogenous near-surface beneath seismic stations can strongly affect the relative amplitudes recorded by three-component seismometers. Using data from Tungurahua volcano we have developed a procedure to correct these `site effects'. We show that seismic noise signals store site information, and then use their normalized spectral amplitudes as site frequency response functions. The process does not require a reference station (as per the S-wave and coda methods) or assume that the vertical amplitude is constant (the H/V component ratio method). Correcting the site effects has three consequences on data analysis: (1) improvement of the seismic source location and its energy estimation; (2) identification of a strong influence on the volcanic acoustic seismic ratio (VASR) and (3) decoupling the air wave impact on the ground caused by explosions or eruption jets. We show how site effect corrections improve the analysis of an eruption jet on 2006 July 14-15, appearing two periods of strong acoustic energy release and a progressive increase of the seismic energy, reaching the maximum before finishing the eruption.

  16. Analysis of clot formation with acoustic radiation force

    NASA Astrophysics Data System (ADS)

    Viola, Francesco; Longo, Diane M.; Lawrence, Michael B.; Walker, William F.

    2002-04-01

    Inappropriate blood coagulation plays an important role in diseases including stroke, heart attack, and deep vein thrombosis (DVT). DVT arises when a blood clot forms in a large vein of the leg. DVT is detrimental because the blood flow may be partially or completely obstructed. More importantly, a potentially fatal situation may arise if part of the clot travels to the arteries in the lungs, forming a pulmonary embolism (PE). Characterization of the mechanical properties of DVT could improve diagnosis and suggest appropriate treatment. We are developing a technique to assess mechanical properties of forming thrombi. The technique uses acoustic radiation force as a means to produce small, localized displacements within the sample. Returned ultrasound echoes are processed to estimate the time dependent displacement of the sample. Appropriate mechanical modeling and signal processing produce plots depicting relative mechanical properties (relative elasticity and relative viscosity) and force-free parameters (time constant, damping ratio, and natural frequency). We present time displacement curves of blood samples obtained during coagulation, and show associated relative and force-free parameter plots. These results show that the Voigt model with added mass accurately characterizes blood behavior during clot formation.

  17. Analysis of In Mine Acoustic Recordings for Single Fired Explosions

    NASA Astrophysics Data System (ADS)

    McKenna, S.; Hayward, C.; Stump, B.

    2003-12-01

    In August of 2003, a series of single fired test shots were executed at a copper mine in Arizona. The ten shots, fired on August 18 and 19, 2003, ranged in size from 1700 lbs to 13600 lbs in simultaneously detonated patterns ranging from a single hole to eight holes. All were located within the same pit and within 100 m of each other. Both free face and bench shots were included. Southern Methodist University had previously deployed a set of acoustic gauges ringing the active production areas of the mine. The five Validyne DP250 sensors recorded not only the ten test shots, but also seven delay fired production shots over the four day period from August 18 to 21, 2003. Each recorded blast arrival was analyzed for peak amplitude and spectrum. Signals were then compared for the variability between shots and sensors as well as a comparison between fully contained and poorly contained shots. Blast yield, scale depth, and centroid depth were compared to the above measured quantities for each of the single-fired and production shots.

  18. Correlation of infrared thermographic patterns and acoustic emission signals with tensile deformation and fracture processes

    NASA Astrophysics Data System (ADS)

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

    2001-04-01

    During tensile deformation, part of the mechanical work done on the specimen is transformed into heat and acoustic activity. The amount of acoustic activity and the thermal emissions depend on the test conditions and the deformation behavior of the specimen during loading. Authors have used thermography and acoustic emission (AE) simultaneously for monitoring tensile deformation in AISI type 316 SS. Tensile testing was carried out at 298 K at three different strain rates. It has been shown that the simultaneous use of these techniques can provide complementary information for characterizing the tensile deformation and fracture processes.

  19. WE-D-BRF-02: Acoustic Signal From the Bragg Peak for Range Verification in Proton Therapy

    SciTech Connect

    Reinhardt, S; Assmann, W; Fink, A; Thirolf, P; Parodi, K; Kellnberger, S; Omar, M; Ntziachristos, V; Gaebisch, C; Moser, M; Dollinger, G; Sergiadis, G

    2014-06-15

    Purpose: Range verification in ion beam therapy relies to date on nuclear imaging techniques which require complex and costly detector systems. A different approach is the detection of thermoacoustic signals that are generated due to localized energy loss of ion beams. Aim of this work is to study the feasibility of determining the ion range with sub-mm accuracy by use of high frequency ultrasonic (US) transducers and to image the Bragg peak by tomography. Methods: A water phantom was irradiated by a pulsed 20 MeV proton beam with varying pulse intensity, length and repetition rate. The acoustic signal of single proton pulses was measured by different PZT-based US detectors (3.5 MHz and 10 MHz central frequencies). For tomography a 64 channel US detector array was used and moved along the ion track by a remotely controlled motor stage. Results: A clear signal of the Bragg peak was visible for an energy deposition as low as 10{sup 12} eV. The signal amplitude showed a linear increase with particle number per pulse and thus, dose. Range measurements were reproducible within +/− 20 micrometer and agreed well with Geant4 simulations. The tomographic reconstruction does not only allow to measure the ion range but also the beam spot size at the Bragg peak position. Conclusion: Range verification by acoustic means is a promising new technique for treatment modalities where the tumor can be localized by US imaging. Further improvement of sensitivity is required to account for higher attenuation of the US signal in tissue, as well as lower energy density in the Bragg peak in realistic treatment cases due to higher particle energy and larger spot sizes. Nevertheless, the acoustic range verification approach could offer the possibility of combining anatomical US imaging with Bragg Peak imaging in the near future. The work was funded by the DFG cluster of excellence Munich Centre for Advanced Photonics (MAP)

  20. Using rotor or tip speed in the acoustical analysis of small wind turbines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acoustical noise data have been collected and analyzed on small wind turbines used for water pumping at the USDA-ARS Conservation and Production Research Laboratory (CPRL) near Bushland, Texas. This acoustical analysis differed from previous research in that the data were analyzed with rotor or tip ...

  1. Acoustic emission analysis as a non-destructive test procedure for fiber compound structures

    NASA Technical Reports Server (NTRS)

    Block, J.

    1983-01-01

    The concept of acoustic emission analysis is explained in scientific terms. The detection of acoustic events, their localization, damage discrimination, and event summation curves are discussed. A block diagram of the concept of damage-free testing of fiber-reinforced synthetic materials is depicted. Prospects for application of the concept are assessed.

  2. A method of construction of information images of the acoustic signals of the human bronchopulmonary system

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    The present study focuses on the development of a method of identification of respiratory sounds and noises of a human naturally and in various pathological conditions. The existing approaches based on a simple method of frequency and time signal analysis, have insufficient specificity, efficiency and unambiguous interpretation of the results of a clinical study. An algorithm for a phase selection of respiratory cycles and analysis of respiratory sounds resulting from bronchi examination of a patient has been suggested. The algorithm is based on the method of phase timing analysis of bronchi phonograms. The results of the phase-frequency algorithm with high resolution reflects a time position of the traceable signals and the individual structure of recorded signals. This allows using the proposed method for the formation of information images (models) of the diagnostically significant fragments. A weight function, frequency parameters of which can be selectively modified, is used for this purpose. The vision of the weighting function is specific to each type of respiratory noise, traditionally referred to quality characteristics (wet or dry noise, crackling, etc.).

  3. Temporal analysis of acoustic emission from a plunged granular bed

    NASA Astrophysics Data System (ADS)

    Tsuji, Daisuke; Katsuragi, Hiroaki

    2015-10-01

    The statistical property of acoustic emission (AE) events from a plunged granular bed is analyzed by means of actual-time and natural-time analyses. These temporal analysis methods allow us to investigate the details of AE events that follow a power-law distribution. In the actual-time analysis, the calm-time distribution, and the decay of the event-occurrence density after the largest event (i.e., the Omori-Utsu law) are measured. Although the former always shows a power-law form, the latter does not always obey a power law. Markovianity of the event-occurrence process is also verified using a scaling law by assuming that both of them exhibit power laws. We find that the effective shear strain rate is a key parameter to classify the emergence rate of power-law nature and Markovianity in granular AE events. For the natural-time analysis, the existence of self-organized critical states is revealed by calculating the variance of natural time χk, where k th natural time of N events is defined as χk=k /N . In addition, the energy difference distribution can be fitted by a q -Gaussian form, which is also consistent with the criticality of the system.

  4. Habituation of Auditory Steady State Responses Evoked by Amplitude-Modulated Acoustic Signals in Rats

    PubMed Central

    Prado-Gutierrez, Pavel; Castro-Fariñas, Anisleidy; Morgado-Rodriguez, Lisbet; Velarde-Reyes, Ernesto; Martínez, Agustín D.; Martínez-Montes, Eduardo

    2015-01-01

    Generation of the auditory steady state responses (ASSR) is commonly explained by the linear combination of random background noise activity and the stationary response. Based on this model, the decrease of amplitude that occurs over the sequential averaging of epochs of the raw data has been exclusively linked to the cancelation of noise. Nevertheless, this behavior might also reflect the non-stationary response of the ASSR generators. We tested this hypothesis by characterizing the ASSR time course in rats with different auditory maturational stages. ASSR were evoked by 8-kHz tones of different supra-threshold intensities, modulated in amplitude at 115 Hz. Results show that the ASSR amplitude habituated to the sustained stimulation and that dishabituation occurred when deviant stimuli were presented. ASSR habituation increased as animals became adults, suggesting that the ability to filter acoustic stimuli with no-relevant temporal information increased with age. Results are discussed in terms of the current model of the ASSR generation and analysis procedures. They might have implications for audiometric tests designed to assess hearing in subjects who cannot provide reliable results in the psychophysical trials. PMID:26557360

  5. Analysis of passive acoustic ranging of helicopters from the joint acoustic propagation experiment

    NASA Technical Reports Server (NTRS)

    Carnes, Benny L.; Morgan, John C.

    1993-01-01

    For more than twenty years, personnel of the U.S.A.E. Waterways Experiment Station (WES) have been performing research dealing with the application of sensors for detection of military targets. The WES research has included the use of seismic, acoustic, magnetic, and other sensors to detect, track, and classify military ground targets. Most of the WES research has been oriented toward the employment of such sensors in a passive mode. Techniques for passive detection are of particular interest in the Army because of the advantages over active detection. Passive detection methods are not susceptible to interception, detection, jamming, or location of the source by the threat. A decided advantage for using acoustic and seismic sensors for detection in tactical situations is the non-line-of-sight capability; i.e., detection of low flying helicopters at long distances without visual contact. This study was conducted to analyze the passive acoustic ranging (PAR) concept using a more extensive data set from the Joint Acoustic Propagation Experiment (JAPE).

  6. Wireless acoustic-electric feed-through for power and signal transmission

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart (Inventor); Bar-Cohen, Yoseph (Inventor); Bao, Xiaoqi (Inventor); Doty, Benjamin (Inventor); Badescu, Mircea (Inventor); Chang, Zensheu (Inventor)

    2011-01-01

    An embodiment provides electrical energy from a source on one side of a medium to a load on the other side of the medium, the embodiment including a first piezoelectric to generate acoustic energy in response to electrical energy from the source, and a second piezoelectric to convert the received acoustic energy to electrical energy used by the load. Other embodiments are described and claimed.

  7. Comparative proteomic analysis of compartmentalised Ras signalling

    PubMed Central

    Hernandez-Valladares, Maria; Prior, Ian A.

    2015-01-01

    Ras proteins are membrane bound signalling hubs that operate from both the cell surface and endomembrane compartments. However, the extent to which intracellular pools of Ras can contribute to cell signalling is debated. To address this, we have performed a global screen of compartmentalised Ras signalling. We find that whilst ER/Golgi- and endosomal-Ras only generate weak outputs, Ras localised to the mitochondria or Golgi significantly and distinctly influence both the abundance and phosphorylation of a wide range of proteins analysed. Our data reveal that ~80% of phosphosites exhibiting large (≥1.5-fold) changes compared to control can be modulated by organellar Ras signalling. The majority of compartmentalised Ras-specific responses are predicted to influence gene expression, RNA splicing and cell proliferation. Our analysis reinforces the concept that compartmentalisation influences Ras signalling and provides detailed insight into the widespread modulation of responses downstream of endomembranous Ras signalling. PMID:26620772

  8. Grey seals use anthropogenic signals from acoustic tags to locate fish: evidence from a simulated foraging task

    PubMed Central

    Stansbury, Amanda L.; Götz, Thomas; Deecke, Volker B.; Janik, Vincent M.

    2015-01-01

    Anthropogenic noise can have negative effects on animal behaviour and physiology. However, noise is often introduced systematically and potentially provides information for navigation or prey detection. Here, we show that grey seals (Halichoerus grypus) learn to use sounds from acoustic fish tags as an indicator of food location. In 20 randomized trials each, 10 grey seals individually explored 20 foraging boxes, with one box containing a tagged fish, one containing an untagged fish and all other boxes being empty. The tagged box was found after significantly fewer non-tag box visits across trials, and seals revisited boxes containing the tag more often than any other box. The time and number of boxes needed to find both fish decreased significantly throughout consecutive trials. Two additional controls were conducted to investigate the role of the acoustic signal: (i) tags were placed in one box, with no fish present in any boxes and (ii) additional pieces of fish, inaccessible to the seal, were placed in the previously empty 18 boxes, making possible alternative chemosensory cues less reliable. During these controls, the acoustically tagged box was generally found significantly faster than the control box. Our results show that animals learn to use information provided by anthropogenic signals to enhance foraging success. PMID:25411449

  9. Grey seals use anthropogenic signals from acoustic tags to locate fish: evidence from a simulated foraging task.

    PubMed

    Stansbury, Amanda L; Götz, Thomas; Deecke, Volker B; Janik, Vincent M

    2015-01-01

    Anthropogenic noise can have negative effects on animal behaviour and physiology. However, noise is often introduced systematically and potentially provides information for navigation or prey detection. Here, we show that grey seals (Halichoerus grypus) learn to use sounds from acoustic fish tags as an indicator of food location. In 20 randomized trials each, 10 grey seals individually explored 20 foraging boxes, with one box containing a tagged fish, one containing an untagged fish and all other boxes being empty. The tagged box was found after significantly fewer non-tag box visits across trials, and seals revisited boxes containing the tag more often than any other box. The time and number of boxes needed to find both fish decreased significantly throughout consecutive trials. Two additional controls were conducted to investigate the role of the acoustic signal: (i) tags were placed in one box, with no fish present in any boxes and (ii) additional pieces of fish, inaccessible to the seal, were placed in the previously empty 18 boxes, making possible alternative chemosensory cues less reliable. During these controls, the acoustically tagged box was generally found significantly faster than the control box. Our results show that animals learn to use information provided by anthropogenic signals to enhance foraging success. PMID:25411449

  10. Applications of Hilbert Spectral Analysis for Speech and Sound Signals

    NASA Technical Reports Server (NTRS)

    Huang, Norden E.

    2003-01-01

    A new method for analyzing nonlinear and nonstationary data has been developed, and the natural applications are to speech and sound signals. The key part of the method is the Empirical Mode Decomposition method with which any complicated data set can be decomposed into a finite and often small number of Intrinsic Mode Functions (IMF). An IMF is defined as any function having the same numbers of zero-crossing and extrema, and also having symmetric envelopes defined by the local maxima and minima respectively. The IMF also admits well-behaved Hilbert transform. This decomposition method is adaptive, and, therefore, highly efficient. Since the decomposition is based on the local characteristic time scale of the data, it is applicable to nonlinear and nonstationary processes. With the Hilbert transform, the Intrinsic Mode Functions yield instantaneous frequencies as functions of time, which give sharp identifications of imbedded structures. This method invention can be used to process all acoustic signals. Specifically, it can process the speech signals for Speech synthesis, Speaker identification and verification, Speech recognition, and Sound signal enhancement and filtering. Additionally, as the acoustical signals from machinery are essentially the way the machines are talking to us. Therefore, the acoustical signals, from the machines, either from sound through air or vibration on the machines, can tell us the operating conditions of the machines. Thus, we can use the acoustic signal to diagnosis the problems of machines.

  11. Comparison of Methods for Identifying Noise Sources in Far-Field Acoustic Signals

    NASA Astrophysics Data System (ADS)

    Tenney, Andrew; Lewalle, Jacques

    2013-11-01

    Three different methods of extracting intermittent wave packets from unstructured background within complex time series signals were analyzed and compared. The algorithms are denoted ``cross correlation,'' ``denoising,'' and ``TFLE (Time-Frequency-Lag event)'' methods respectively. All three methods utilize Mexican Hat or Morlet wavelets for the transformation of time domain signals into time-frequency domain signals. Within the denoising and cross correlation algorithms, events are identified through comparison of high energy excerpts of each signal captured by individual far-field microphones, while the TFLE algorithm simply defines events by their contributions to positive correlation values. The goal of this analysis is to quantify the advantages and disadvantages of each of these methods. The results lend themselves to determining the validity of these methods as noise source identification algorithms to be used in jet noise characterization. This work is supported in part by Spectral Energies LLC, under an SBIR grant from AFRL; and by the Department of Mechanical and Aerospace Engineering REU Program at SU.

  12. Single-point nonlinearity indicators for the propagation of high-amplitude acoustic signals

    NASA Astrophysics Data System (ADS)

    Falco, Lauren E.

    . Both single-frequency signals and band-limited noise were used as sources, and waveforms were recorded at all four propagation distances. The second set of data was obtained at the model-scale jet facility at the University of Mississippi's National Center for Physical Acoustics. A computer controlled microphone boom was constructed to hold an array of six microphones. The array was rotated about the presumed location of the acoustic source center (4 jet diameters downstream of the nozzle exit), and two stationary microphones were mounted on the walls. Measurements were made for several jet conditions; data presented here represent Mach 0.85 and Mach 2 conditions. Application of the four candidate nonlinearity indicators to the experimental data reveals that each indicator has advantages and disadvantages. Qneg/Qpos does not detect the presence of shocks as postulated, but it does conform to expectations in the shock-free region and support the use of Qpos as an indicator. The main advantage of Qpos/p3rms is that it can be used for band-limited measurements. Increased indicator values are seen for signals with higher source frequencies and amplitudes that are expected to undergo stronger nonlinear evolution. However, no physical meaning can yet be derived from the numerical value of the indicator. The spectral Gol'dberg number Gammas is the most promising of the candidate quantities. It has the ability to indicate the direction of nonlinear energy transfer as well as provide a comparison between the strengths of linear and nonlinear effects. These attributes allow it to be used to qualitatively predict the evolution of a spectrum. The coherence indicator gammaQ also specifies the direction of nonlinear energy transfer, but its numerical value holds less meaning. However, it is bounded between -1 and 1, so values near zero denote very weak or no nonlinearity, and values near -1 or 1 denote strong nonlinearity. Further, because it is bounded, it does not become unstable

  13. Optimal design and evaluation criteria for acoustic emission pulse signature analysis

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    Successful pulse recording and evaluation is strongly dependent on the instrumentation system selected and the method of analyzing the pulse signature. The paper studies system design, signal analysis techniques, and interdependences with a view toward defining optimal approaches to pulse signal analysis. For this purpose, the instrumentation system is modeled, and analytical pulses, representative of the types of acoustic emissions to be distinguished are passed through the system. Particular attention is given to comparing frequency spectrum analysis and deconvolution referred to as time domain reconstruction of the pulse or pulse train. The possibility of optimal transducer-filter system parameters is investigated. Deconvolution of a pulse is shown to be a superior approach for transient pulse analysis. Reshaping of a transducer output back to the original input pulse is possible and gives an accurate representation of the generating pulse in the time domain. Any definable transducer and filter system can be used for measurement of pulses by means of the deconvolution method. Selection of design variables for general usage is discussed.

  14. Seismo-acoustic analysis of thunderstorms at Plostina (Romania) site

    NASA Astrophysics Data System (ADS)

    Grecu, Bogdan; Ghica, Daniela; Moldovan, Iren; Ionescu, Constantin

    2013-04-01

    The National Institute for Earth Physics (Romania) operates one of the largest seismic networks in the Eastern Europe. The network includes 97 stations with velocity sensors of which 52 are broadband and 45 are short period, 102 strong motion stations and 8 seismic observatories. Located in the most active seismic region of Romania, i.e. Vrancea area, the Plostina Observatory included initially two seismic stations, one at surface with both broadband and accelerometer sensors and one at 30 m depth with only short period velocity sensor. Starting with 2007, the facilities at Plostina have been upgraded so that at present, the observatory also includes one seismic array (PLOR) of seven elements (PLOR1, PLOR2, PLOR3, PLOR4, PLOR5, PLOR6, PLOR7) with an aperture of 2.5 km, seven infrasound elements (IPL2, IPL3, IPL4, IPH4, IPH5, IPH6, IPH7), two three-component fluxgate sensors, one Boltek EFM-100 electrometer and one La Crosse weather station. The element PLOR4 is co-located with the accelerometer and borehole sensor, two infrasonic elements (IPL4 and IPH4), one fluxgate sensor, the Boltek electrometer and the weather station. All the date are continuously recorded and real-time transmitted to the Romanian National Data Centre (RONDC) in Magurele. The recent developments at Plostina site made possible the improvement of the local miscroseismic activity monitoring as well as conducting of other geophysical studies such as acoustic measurements, observations of the variation of the magnetic field in correlation with solar activity, observations of the variation of radioactive alpha gases concentration, observations of the telluric currents. In this work, we investigate the signals emitted due to the process of lightning and thunder during thunderstorms activity at Plostina site. These signals are well recorded by both seismic and infrasound networks and they are used to perform spectral and specific array analyses. We also perform multiple correlations between the

  15. A Neural Network/Acoustic Emission Analysis of Impact Damaged Graphite/Epoxy Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Walker, James L.; Hill, Erik v. K.; Workman, Gary L.; Russell, Samuel S.

    1995-01-01

    Acoustic emission (AE) signal analysis has been used to measure the effects of impact damage on burst pressure in 5.75 inch diameter, inert propellant filled, filament wound pressure vessels. The AE data were collected from fifteen graphite/epoxy pressure vessels featuring five damage states and three resin systems. A burst pressure prediction model was developed by correlating the AE amplitude (frequency) distribution, generated during the first pressure ramp to 800 psig (approximately 25% of the average expected burst pressure for an undamaged vessel) to known burst pressures using a four layered back propagation neural network. The neural network, trained on three vessels from each resin system, was able to predict burst pressures with a worst case error of 5.7% for the entire fifteen bottle set.

  16. Parallel feedback active noise control of MRI acoustic noise with signal decomposition using hybrid RLS-NLMS adaptive algorithms.

    PubMed

    Ganguly, Anshuman; Krishna Vemuri, Sri Hari; Panahi, Issa

    2014-01-01

    This paper presents a cost-effective adaptive feedback Active Noise Control (FANC) method for controlling functional Magnetic Resonance Imaging (fMRI) acoustic noise by decomposing it into dominant periodic components and residual random components. Periodicity of fMRI acoustic noise is exploited by using linear prediction (LP) filtering to achieve signal decomposition. A hybrid combination of adaptive filters-Recursive Least Squares (RLS) and Normalized Least Mean Squares (NLMS) are then used to effectively control each component separately. Performance of the proposed FANC system is analyzed and Noise attenuation levels (NAL) up to 32.27 dB obtained by simulation are presented which confirm the effectiveness of the proposed FANC method. PMID:25570676

  17. Acoustic Analysis of Inhaler Sounds From Community-Dwelling Asthmatic Patients for Automatic Assessment of Adherence

    PubMed Central

    D'arcy, Shona; Costello, Richard W.

    2014-01-01

    Inhalers are devices which deliver medication to the airways in the treatment of chronic respiratory diseases. When used correctly inhalers relieve and improve patients' symptoms. However, adherence to inhaler medication has been demonstrated to be poor, leading to reduced clinical outcomes, wasted medication, and higher healthcare costs. There is a clinical need for a system that can accurately monitor inhaler adherence as currently no method exists to evaluate how patients use their inhalers between clinic visits. This paper presents a method of automatically evaluating inhaler adherence through acoustic analysis of inhaler sounds. An acoustic monitoring device was employed to record the sounds patients produce while using a Diskus dry powder inhaler, in addition to the time and date patients use the inhaler. An algorithm was designed and developed to automatically detect inhaler events from the audio signals and provide feedback regarding patient adherence. The algorithm was evaluated on 407 audio files obtained from 12 community dwelling asthmatic patients. Results of the automatic classification were compared against two expert human raters. For patient data for whom the human raters Cohen's kappa agreement score was \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}${>}{0.81}$\\end{document}, results indicated that the algorithm's accuracy was 83% in determining the correct inhaler technique score compared with the raters. This paper has several clinical implications as it demonstrates the feasibility of using acoustics to objectively monitor patient inhaler adherence and provide real-time personalized medical care for a chronic respiratory illness. PMID:27170883

  18. Acoustic analysis and mood classification of pain-relieving music.

    PubMed

    Knox, Don; Beveridge, Scott; Mitchell, Laura A; MacDonald, Raymond A R

    2011-09-01

    Listening to preferred music (that which is chosen by the participant) has been shown to be effective in mitigating the effects of pain when compared to silence and a variety of distraction techniques. The wide range of genre, tempo, and structure in music chosen by participants in studies utilizing experimentally induced pain has led to the assertion that structure does not play a significant role, rather listening to preferred music renders the music "functionally equivalent" as regards its effect upon pain perception. This study addresses this assumption and performs detailed analysis of a selection of music chosen from three pain studies. Music analysis showed significant correlation between timbral and tonal aspects of music and measurements of pain tolerance and perceived pain intensity. Mood classification was performed using a hierarchical Gaussian Mixture Model, which indicated the majority of the chosen music expressed contentment. The results suggest that in addition to personal preference, associations with music and the listening context, emotion expressed by music, as defined by its acoustical content, is important to enhancing emotional engagement with music and therefore enhances the level of pain reduction and tolerance. PMID:21895104

  19. Acoustic emission analysis of tooth-composite interfacial debonding.

    PubMed

    Cho, N Y; Ferracane, J L; Lee, I B

    2013-01-01

    This study detected tooth-composite interfacial debonding during composite restoration by means of acoustic emission (AE) analysis and investigated the effects of composite properties and adhesives on AE characteristics. The polymerization shrinkage, peak shrinkage rate, flexural modulus, and shrinkage stress of a methacrylate-based universal hybrid, a flowable, and a silorane-based composite were measured. Class I cavities on 49 extracted premolars were restored with 1 of the 3 composites and 1 of the following adhesives: 2 etch-and-rinse adhesives, 2 self-etch adhesives, and an adhesive for the silorane-based composite. AE analysis was done for 2,000 sec during light-curing. The silorane-based composite exhibited the lowest shrinkage (rate), the longest time to peak shrinkage rate, the lowest shrinkage stress, and the fewest AE events. AE events were detected immediately after the beginning of light-curing in most composite-adhesive combinations, but not until 40 sec after light-curing began for the silorane-based composite. AE events were concentrated at the initial stage of curing in self-etch adhesives compared with etch-and-rinse adhesives. Reducing the shrinkage (rate) of composites resulted in reduced shrinkage stress and less debonding, as evidenced by fewer AE events. AE is an effective technique for monitoring, in real time, the debonding kinetics at the tooth-composite interface. PMID:23100273

  20. Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis.

    PubMed

    Yoon, Sung Hwan; Huang, Yue; Edgar, J Scott; Ting, Ying S; Heron, Scott R; Kao, Yuchieh; Li, Yanyan; Masselon, Christophe D; Ernst, Robert K; Goodlett, David R

    2012-08-01

    Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis. PMID:22742654

  1. Prediction of ultrasound-mediated disruption of cell membranes using machine learning techniques and statistical analysis of acoustic spectra.

    PubMed

    Lee, Eva K; Gallagher, Richard J; Campbell, Ann Melissa; Prausnitz, Mark R

    2004-01-01

    Although biological effects of ultrasound must be avoided for safe diagnostic applications, ultrasound's ability to disrupt cell membranes has attracted interest as a method to facilitate drug and gene delivery. This paper seeks to develop "prediction rules" for predicting the degree of cell membrane disruption based on specified ultrasound parameters and measured acoustic signals. Three techniques for generating prediction rules (regression analysis, classification trees and discriminant analysis) are applied to data obtained from a sequence of experiments on bovine red blood cells. For each experiment, the data consist of four ultrasound parameters, acoustic measurements at 400 frequencies, and a measure of cell membrane disruption. To avoid over-training, various combinations of the 404 predictor variables are used when applying the rule generation methods. The results indicate that the variable combination consisting of ultrasound exposure time and acoustic signals measured at the driving frequency and its higher harmonics yields the best rule for all three rule generation methods. The methods used for deriving the prediction rules are broadly applicable, and could be used to develop prediciton rules in other scenarios involving different cell types or tissues. These rules and the methods used to derive them could be used for real-time feedback about ultrasound's biological effects. PMID:14723497

  2. A Correlated Study of the Response of a Satellite to Acoustic Radiation Using Statistical Energy Analysis and Acoustic Test Data

    SciTech Connect

    CAP,JEROME S.; TRACEY,BRIAN

    1999-11-15

    Aerospace payloads, such as satellites, are subjected to vibroacoustic excitation during launch. Sandia's MTI satellite has recently been certified to this environment using a combination of base input random vibration and reverberant acoustic noise. The initial choices for the acoustic and random vibration test specifications were obtained from the launch vehicle Interface Control Document (ICD). In order to tailor the random vibration levels for the laboratory certification testing, it was necessary to determine whether vibration energy was flowing across the launch vehicle interface from the satellite to the launch vehicle or the other direction. For frequencies below 120 Hz this issue was addressed using response limiting techniques based on results from the Coupled Loads Analysis (CLA). However, since the CLA Finite Element Analysis FEA model was only correlated for frequencies below 120 Hz, Statistical Energy Analysis (SEA) was considered to be a better choice for predicting the direction of the energy flow for frequencies above 120 Hz. The existing SEA model of the launch vehicle had been developed using the VibroAcoustic Payload Environment Prediction System (VAPEPS) computer code [1]. Therefore, the satellite would have to be modeled using VAPEPS as well. As is the case for any computational model, the confidence in its predictive capability increases if one can correlate a sample prediction against experimental data. Fortunately, Sandia had the ideal data set for correlating an SEA model of the MTI satellite--the measured response of a realistic assembly to a reverberant acoustic test that was performed during MTI's qualification test series. The first part of this paper will briefly describe the VAPEPS modeling effort and present the results of the correlation study for the VAPEPS model. The second part of this paper will present the results from a study that used a commercial SEA software package [2] to study the effects of in-plane modes and to

  3. Combustion-acoustic stability analysis for premixed gas turbine combustors

    NASA Technical Reports Server (NTRS)

    Darling, Douglas; Radhakrishnan, Krishnan; Oyediran, Ayo; Cowan, Lizabeth

    1995-01-01

    Lean, prevaporized, premixed combustors are susceptible to combustion-acoustic instabilities. A model was developed to predict eigenvalues of axial modes for combustion-acoustic interactions in a premixed combustor. This work extends previous work by including variable area and detailed chemical kinetics mechanisms, using the code LSENS. Thus the acoustic equations could be integrated through the flame zone. Linear perturbations were made of the continuity, momentum, energy, chemical species, and state equations. The qualitative accuracy of our approach was checked by examining its predictions for various unsteady heat release rate models. Perturbations in fuel flow rate are currently being added to the model.

  4. Chemical analysis of acoustically levitated drops by Raman spectroscopy.

    PubMed

    Tuckermann, Rudolf; Puskar, Ljiljana; Zavabeti, Mahta; Sekine, Ryo; McNaughton, Don

    2009-07-01

    An experimental apparatus combining Raman spectroscopy with acoustic levitation, Raman acoustic levitation spectroscopy (RALS), is investigated in the field of physical and chemical analytics. Whereas acoustic levitation enables the contactless handling of microsized samples, Raman spectroscopy offers the advantage of a noninvasive method without complex sample preparation. After carrying out some systematic tests to probe the sensitivity of the technique to drop size, shape, and position, RALS has been successfully applied in monitoring sample dilution and preconcentration, evaporation, crystallization, an acid-base reaction, and analytes in a surface-enhanced Raman spectroscopy colloidal suspension. PMID:19418043

  5. [Music-Acoustic Signals Controlled by Subject's Brain Potentials in the Correction of Unfavorable Functional States].

    PubMed

    Fedotchev, A I; Bondar, A T; Bakhchina, A V; Parin, S B; Polevaya, S A; Radchenko, G S

    2016-01-01

    Literature review and the results of own studies on the development and experimental testing of musical EEG neurofeedback technology are presented. The technology is based on exposure of subjects to music or music-like signals that are organized in strict accordance with the current values of brain potentials of the patient. The main attention is paid to the analysis of the effectiveness of several versions of the technology, using specific and meaningful for the individual narrow-frequency EEG oscillators during the correction of unfavorable changes of the functional state. PMID:27149824

  6. Wear detection by means of wavelet-based acoustic emission analysis

    NASA Astrophysics Data System (ADS)

    Baccar, D.; Söffker, D.

    2015-08-01

    Wear detection and monitoring during operation are complex and difficult tasks especially for materials under sliding conditions. Due to the permanent contact and repetitive motion, the material surface remains during tests non-accessible for optical inspection so that attrition of the contact partners cannot be easily detected. This paper introduces the relevant scientific components of reliable and efficient condition monitoring system for online detection and automated classification of wear phenomena by means of acoustic emission (AE) and advanced signal processing approaches. The related experiments were performed using a tribological system consisting of two martensitic plates, sliding against each other. High sensitive piezoelectric transducer was used to provide the continuous measurement of AE signals. The recorded AE signals were analyzed mainly by time-frequency analysis. A feature extraction module using a novel combination of Short-Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT) were used for the first time. A detailed correlation analysis between complex signal characteristics and the surface damage resulting from contact fatigue was investigated. Three wear process stages were detected and could be distinguished. To obtain quantitative and detailed information about different wear phases, the AE energy was calculated using STFT and decomposed into a suitable number of frequency levels. The individual energy distribution and the cumulative AE energy of each frequency components were analyzed using CWT. Results show that the behavior of individual frequency component changes when the wear state changes. Here, specific frequency ranges are attributed to the different wear states. The study reveals that the application of the STFT-/CWT-based AE analysis is an appropriate approach to distinguish and to interpret the different damage states occurred during sliding contact. Based on this results a new generation of condition monitoring

  7. Thermal Acoustic Oscillation: Causes, Detection, Analysis and Prevention

    NASA Technical Reports Server (NTRS)

    Christie, Robert J.; Hartwig, Jason W.

    2014-01-01

    The presentation discusses the causes of Thermal Acoustic Oscillations, how it can be detected, analyzed and prevented. It also discusses where it can occur, where it doesn't occur and practical mitigation techniques.

  8. Acoustic modal analysis of a full-scale annular combustor

    NASA Technical Reports Server (NTRS)

    Karchmer, A. M.

    1982-01-01

    An acoustic modal decomposition of the measured pressure field in a full scale annular combustor installed in a ducted test rig is described. The modal analysis, utilizing a least squares optimization routine, is facilitated by the assumption of randomly occurring pressure disturbances which generate equal amplitude clockwise and counter-clockwise pressure waves, and the assumption of statistical independence between modes. These assumptions are fully justified by the measured cross spectral phases between the various measurement points. The resultant modal decomposition indicates that higher order modes compose the dominant portion of the combustor pressure spectrum in the range of frequencies of interest in core noise studies. A second major finding is that, over the frequency range of interest, each individual mode which is present exists in virtual isolation over significant portions of the spectrum. Finally, a comparison between the present results and a limited amount of data obtained in an operating turbofan engine with the same combustor is made. The comparison is sufficiently favorable to warrant the conclusion that the structure of the combustor pressure field is preserved between the component facility and the engine.

  9. Analysis of Measured and Simulated Supraglottal Acoustic Waves.

    PubMed

    Fraile, Rubén; Evdokimova, Vera V; Evgrafova, Karina V; Godino-Llorente, Juan I; Skrelin, Pavel A

    2016-09-01

    To date, although much attention has been paid to the estimation and modeling of the voice source (ie, the glottal airflow volume velocity), the measurement and characterization of the supraglottal pressure wave have been much less studied. Some previous results have unveiled that the supraglottal pressure wave has some spectral resonances similar to those of the voice pressure wave. This makes the supraglottal wave partially intelligible. Although the explanation for such effect seems to be clearly related to the reflected pressure wave traveling upstream along the vocal tract, the influence that nonlinear source-filter interaction has on it is not as clear. This article provides an insight into this issue by comparing the acoustic analyses of measured and simulated supraglottal and voice waves. Simulations have been performed using a high-dimensional discrete vocal fold model. Results of such comparative analysis indicate that spectral resonances in the supraglottal wave are mainly caused by the regressive pressure wave that travels upstream along the vocal tract and not by source-tract interaction. On the contrary and according to simulation results, source-tract interaction has a role in the loss of intelligibility that happens in the supraglottal wave with respect to the voice wave. This loss of intelligibility mainly corresponds to spectral differences for frequencies above 1500 Hz. PMID:26377510

  10. Theoretical analysis of a cell's oscillations in an acoustic field

    NASA Astrophysics Data System (ADS)

    Allen, John S.; Zinin, Pavel

    2005-09-01

    The analysis and deformation of an individual cell in a high-frequency acoustic field is of fundamental interest for a variety of applications such as ultrasound cell separation and drug delivery. The oscillations of biological cells in a sound field are investigated using a shell model for the cell following an approach developed previously [Zinin, Ultrasonics, 30, 26-34 (1992)]. The model accounts for the three components which comprise the cell's motion: the internal fluid (cytoplasma), the cell membrane, and the surrounding fluid. The cell membrane whose thickness is small compared to the cell radius can be approximated as a thin elastic shell. The elastic properties of this shell together with the viscosities of the internal and external fluids determine the oscillations of the cell. The dipole oscillations of the cell depend on the surface area modulus and the maximum frequency for the relative change in cell area can be determined. Moreover, the higher order oscillations starting with the quadrupole oscillations are governed by the shell's shear modulus. Induced stresses in bacteria cell membranes in the vicinity of an oscillating bubble are investigated and cell rupture with respect to these stresses is analyzed.

  11. Acoustic modal analysis of a full-scale annular combustor

    NASA Technical Reports Server (NTRS)

    Karchmer, A. M.

    1983-01-01

    An acoustic modal decomposition of the measured pressure field in a full scale annular combustor installed in a ducted test rig is described. The modal analysis, utilizing a least squares optimization routine, is facilitated by the assumption of randomly occurring pressure disturbances which generate equal amplitude clockwise and counter-clockwise pressure waves, and the assumption of statistical independence between modes. These assumptions are fully justified by the measured cross spectral phases between the various measurement points. The resultant modal decomposition indicates that higher order modes compose the dominant portion of the combustor pressure spectrum in the range of frequencies of interest in core noise studies. A second major finding is that, over the frequency range of interest, each individual mode which is present exists in virtual isolation over significant portions of the spectrum. Finally, a comparison between the present results and a limited amount of data obtained in an operating turbofan engine with the same combustor is made. The comparison is sufficiently favorable to warrant the conclusion that the structure of the combustor pressure field is preserved between the component facility and the engine. Previously announced in STAR as N83-21896

  12. Parallel Finite Element Domain Decomposition for Structural/Acoustic Analysis

    NASA Technical Reports Server (NTRS)

    Nguyen, Duc T.; Tungkahotara, Siroj; Watson, Willie R.; Rajan, Subramaniam D.

    2005-01-01

    A domain decomposition (DD) formulation for solving sparse linear systems of equations resulting from finite element analysis is presented. The formulation incorporates mixed direct and iterative equation solving strategics and other novel algorithmic ideas that are optimized to take advantage of sparsity and exploit modern computer architecture, such as memory and parallel computing. The most time consuming part of the formulation is identified and the critical roles of direct sparse and iterative solvers within the framework of the formulation are discussed. Experiments on several computer platforms using several complex test matrices are conducted using software based on the formulation. Small-scale structural examples are used to validate thc steps in the formulation and large-scale (l,000,000+ unknowns) duct acoustic examples are used to evaluate the ORIGIN 2000 processors, and a duster of 6 PCs (running under the Windows environment). Statistics show that the formulation is efficient in both sequential and parallel computing environmental and that the formulation is significantly faster and consumes less memory than that based on one of the best available commercialized parallel sparse solvers.

  13. Asymptotic modal analysis and statistical energy analysis of an acoustic cavity

    NASA Technical Reports Server (NTRS)

    Kubota, Y.; Dionne, H. D.; Dowell, E. H.

    1988-01-01

    A basic asymptotic theory for structural wall/acoustic cavity interaction is presented, and the analysis is illustrated with examples of the acoustic cavity response to a prescribed wall motion. Although, when spatially averaged, the classical modal analysis (CMA) response approaches the asymptotic modal analysis (AMA) response more rapidly as the number of modes increases, it is shown that information about local response intensification is lost in the averaging process. A larger bandwidth at a given center frequency is found to contain more excited modes than a smaller bandwidth; however, the AMA is slightly more accurate in the smaller bandwidth. All AMA asymptotes were shown to be approached from below by a CMA with fixed bandwidth and increasing center frequency.

  14. Rhythm analysis of orthogonal signals from human walking.

    PubMed

    Ekimov, Alexander; Sabatier, James M

    2011-03-01

    In physical terms, periodic movements of a human body resulting from walking produce a pulse sequence with repetition time T(1) (instant cadence frequency, 1/T(1)) and duration time T(2). Footstep forces generate periodic T(1) broadband seismic and sound signals due to the dynamic forces between the foot and the ground/floor with duration time T(2), which is equal to the time interval for a single footstep from heel strike to toe slap and weight transfer. In a human gait study (for normal speeds of walking), T(1) was detected as 0.5-0.69 s and double limb support takes up about 12% of the gait cycle (2T(1)), so T(2) is greater than 0.12-0.17 s. Short range (of about 50 m) signatures for 30 humans were recorded simultaneously by four orthogonal sensor types at two locations. The sensor types were active Doppler sonar/radar and passive seismic/acoustics. Analysis of signals from these four sensors collected for walking humans showed temporal synchronization and stability of the cadence frequencies, and the cadence frequency from each sensor was equivalent. The time delay between signals from these sensors due to the differences in speeds of propagation for seismic, sound, and electromagnetic waves allows calculation of the distance from a walker to the sensor suite. PMID:21428494

  15. Spectral analysis of ELT signals for SARSAT

    NASA Astrophysics Data System (ADS)

    Dessouky, M. I.; Carter, C. R.

    1987-09-01

    Search and rescue satellite-aided tracking (SARSAT) relays the emergency locator transmitter (ELT) signals of distressed aircraft to an earth station for spectral analysis. Of considerable importance are the characteristics of the spectrum of the ELT signal since the probability of locating the downed aircraft is closely related to the quality of the ELT signal spectrum itself. In this paper, it is shown that the spectrum can be adversely affected by a number of factors including the phase and frequency characteristics of the carrier and their interaction with the amplitude modulation. Two new models are proposed which greatly reduce the self-generated interference produced by ELT units presently being used.

  16. Mate call as reward: Acoustic communication signals can acquire positive reinforcing values during adulthood in female zebra finches (Taeniopygia guttata).

    PubMed

    Hernandez, Alexandra M; Perez, Emilie C; Mulard, Hervé; Mathevon, Nicolas; Vignal, Clémentine

    2016-02-01

    Social stimuli can have rewarding properties and promote learning. In birds, conspecific vocalizations like song can act as a reinforcer, and specific song variants can acquire particular rewarding values during early life exposure. Here we ask if, during adulthood, an acoustic signal simpler and shorter than song can become a reward for a female songbird because of its particular social value. Using an operant choice apparatus, we showed that female zebra finches display a preferential response toward their mate's calls. This reinforcing value of mate's calls could be involved in the maintenance of the monogamous pair-bond of the zebra finch. PMID:26881942

  17. An analysis and retrofit of the acoustics at Image Creators Health and Beauty Salon

    NASA Astrophysics Data System (ADS)

    Ellis, Donna

    2002-11-01

    This paper discusses the analysis and retrofit of the acoustics in a high-volume beauty salon in Severna Park, MD. The major issues in what was designed to be a serene environment are reverberation times of 1-1.68 s in the mid- to upper-frequency range. Employee and customer complaints include heightened stress, vocal strain, headaches, and poor intelligibility. Existing analysis and acoustical retrofit solutions will be demonstrated.

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

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

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

  19. Modification of computational auditory scene analysis (CASA) for noise-robust acoustic feature

    NASA Astrophysics Data System (ADS)

    Kwon, Minseok

    While there have been many attempts to mitigate interferences of background noise, the performance of automatic speech recognition (ASR) still can be deteriorated by various factors with ease. However, normal hearing listeners can accurately perceive sounds of their interests, which is believed to be a result of Auditory Scene Analysis (ASA). As a first attempt, the simulation of the human auditory processing, called computational auditory scene analysis (CASA), was fulfilled through physiological and psychological investigations of ASA. CASA comprised of Zilany-Bruce auditory model, followed by tracking fundamental frequency for voice segmentation and detecting pairs of onset/offset at each characteristic frequency (CF) for unvoiced segmentation. The resulting Time-Frequency (T-F) representation of acoustic stimulation was converted into acoustic feature, gammachirp-tone frequency cepstral coefficients (GFCC). 11 keywords with various environmental conditions are used and the robustness of GFCC was evaluated by spectral distance (SD) and dynamic time warping distance (DTW). In "clean" and "noisy" conditions, the application of CASA generally improved noise robustness of the acoustic feature compared to a conventional method with or without noise suppression using MMSE estimator. The intial study, however, not only showed the noise-type dependency at low SNR, but also called the evaluation methods in question. Some modifications were made to capture better spectral continuity from an acoustic feature matrix, to obtain faster processing speed, and to describe the human auditory system more precisely. The proposed framework includes: 1) multi-scale integration to capture more accurate continuity in feature extraction, 2) contrast enhancement (CE) of each CF by competition with neighboring frequency bands, and 3) auditory model modifications. The model modifications contain the introduction of higher Q factor, middle ear filter more analogous to human auditory system

  20. Acoustic propagation in the Hudson River Estuary: Analysis of experimental measurements and numerical modeling results

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, Sreeram

    Underwater intrusion detection is an ongoing security concern in port and harbor areas. Of particular interest is to detect SCUBA divers, unmanned underwater vehicles and small boats from their acoustic signature. A thorough understanding of the effects of the shallow water propagating medium on acoustic signals can help develop new technologies and improve the performance of existing acoustic based surveillance systems. The Hudson River Estuary provides us with such a shallow water medium to conduct research and improve our knowledge of shallow water acoustics. Acoustic propagation in the Hudson River Estuary is highly affected by the temporal and spatial variability of salinity and temperature due to tides, freshwater inflows, winds etc. The primary goal of this research is to help develop methodologies to predict the formation of an acoustic field in the realistic environment of the lower Hudson River Estuary. Shallow water high-frequency acoustic propagation experiments were conducted in the Hudson River near Hoboken, New Jersey. Channel Impulse Response (CIR) measurements were carried out in the frequency band from 10 to 100 kHz for distances up to 200 meters in a water depth of 8-10 meters which formed the basis for experimental Transmission Loss (TL). CIR data was also utilized to demonstrate multi-path propagation in shallow water. Acoustic propagation models based on Ray Theory and Parabolic Equation methods were implemented in the frequency band from 10 to 100 kHz and TL was estimated. The sound velocity profiles required as input by acoustic propagation models were calculated from in-situ measurements of temperature, salinity and depth. Surface reflection loss was obtained from CIR data and incorporated into the acoustic propagation models. Experimentally obtained TL was used to validate the acoustic model predictions. An outcome of this research is an operational acoustic transmission loss (TL) forecast system based on the existing, Stevens New York

  1. Acoustic duetting in Drosophila virilis relies on the integration of auditory and tactile signals.

    PubMed

    LaRue, Kelly M; Clemens, Jan; Berman, Gordon J; Murthy, Mala

    2015-01-01

    Many animal species, including insects, are capable of acoustic duetting, a complex social behavior in which males and females tightly control the rate and timing of their courtship song syllables relative to each other. The mechanisms underlying duetting remain largely unknown across model systems. Most studies of duetting focus exclusively on acoustic interactions, but the use of multisensory cues should aid in coordinating behavior between individuals. To test this hypothesis, we develop Drosophila virilis as a new model for studies of duetting. By combining sensory manipulations, quantitative behavioral assays, and statistical modeling, we show that virilis females combine precisely timed auditory and tactile cues to drive song production and duetting. Tactile cues delivered to the abdomen and genitalia play the larger role in females, as even headless females continue to coordinate song production with courting males. These data, therefore, reveal a novel, non-acoustic, mechanism for acoustic duetting. Finally, our results indicate that female-duetting circuits are not sexually differentiated, as males can also produce 'female-like' duets in a context-dependent manner. PMID:26046297

  2. Acoustic duetting in Drosophila virilis relies on the integration of auditory and tactile signals

    PubMed Central

    LaRue, Kelly M; Clemens, Jan; Berman, Gordon J; Murthy, Mala

    2015-01-01

    Many animal species, including insects, are capable of acoustic duetting, a complex social behavior in which males and females tightly control the rate and timing of their courtship song syllables relative to each other. The mechanisms underlying duetting remain largely unknown across model systems. Most studies of duetting focus exclusively on acoustic interactions, but the use of multisensory cues should aid in coordinating behavior between individuals. To test this hypothesis, we develop Drosophila virilis as a new model for studies of duetting. By combining sensory manipulations, quantitative behavioral assays, and statistical modeling, we show that virilis females combine precisely timed auditory and tactile cues to drive song production and duetting. Tactile cues delivered to the abdomen and genitalia play the larger role in females, as even headless females continue to coordinate song production with courting males. These data, therefore, reveal a novel, non-acoustic, mechanism for acoustic duetting. Finally, our results indicate that female-duetting circuits are not sexually differentiated, as males can also produce ‘female-like’ duets in a context-dependent manner. DOI: http://dx.doi.org/10.7554/eLife.07277.001 PMID:26046297

  3. Reflex Modification by Acoustic Signals in Newborn Infants and in Adults.

    ERIC Educational Resources Information Center

    Hoffman, Howard S.; And Others

    1985-01-01

    Five experiments using identical reflex modification procedures on neonates and adults suggest developmental differences in processing auditory stimuli. Neonates failed to exhibit reflex inhibition by either prior acoustic or tactile stimuli. Adults exhibited robust reflex inhibition to these same stimuli. Developmental processes implied by these…

  4. Nonlinear adaptive wavelet analysis of electrocardiogram signals

    NASA Astrophysics Data System (ADS)

    Yang, H.; Bukkapatnam, S. T.; Komanduri, R.

    2007-08-01

    Wavelet representation can provide an effective time-frequency analysis for nonstationary signals, such as the electrocardiogram (EKG) signals, which contain both steady and transient parts. In recent years, wavelet representation has been emerging as a powerful time-frequency tool for the analysis and measurement of EKG signals. The EKG signals contain recurring, near-periodic patterns of P , QRS , T , and U waveforms, each of which can have multiple manifestations. Identification and extraction of a compact set of features from these patterns is critical for effective detection and diagnosis of various disorders. This paper presents an approach to extract a fiducial pattern of EKG based on the consideration of the underlying nonlinear dynamics. The pattern, in a nutshell, is a combination of eigenfunctions of the ensembles created from a Poincare section of EKG dynamics. The adaptation of wavelet functions to the fiducial pattern thus extracted yields two orders of magnitude (some 95%) more compact representation (measured in terms of Shannon signal entropy). Such a compact representation can facilitate in the extraction of features that are less sensitive to extraneous noise and other variations. The adaptive wavelet can also lead to more efficient algorithms for beat detection and QRS cancellation as well as for the extraction of multiple classical EKG signal events, such as widths of QRS complexes and QT intervals.

  5. Damage analysis of CFRP-confined circular concrete-filled steel tubular columns by acoustic emission techniques

    NASA Astrophysics Data System (ADS)

    Li, Dongsheng; Chen, Zhi; Feng, Quanming; Wang, Yanlei

    2015-08-01

    Damage properties of carbon fiber-reinforced polymer (CFRP) confined circular concrete-filled steel tubular (CCFT) columns were analyzed through acoustic emission (AE) signals. AE characteristic parameters were obtained through axial compression tests. The severity of damage to CFRP-CCFT columns was estimated using the growing trend of AE accumulated energy as basis. The bearing capacity of CFRP-CCFT columns and AE accumulated energy improved as CFRP layers increased. The damage process was studied using a number of crucial AE parameters. The cracks’ mode can be differentiated through the ratio of the rise time to the waveform amplitude and through average frequency analysis. With the use of intensity signal analysis, the damage process of the CFRP-CCFT columns can be classified into three levels that represent different degrees. Based on b-value analysis, the development of the obtained cracks can be defined. Thus, identifying an initial yielding and providing early warning is possible.

  6. Graphical analysis of electron inertia induced acoustic instability

    NASA Astrophysics Data System (ADS)

    Karmakar, P. K.; Deka, U.; Dwivedi, C. B.

    2005-03-01

    Recently, the practical significance of the asymptotic limit of me/mi→0 for electron density distribution has been judged in a two-component plasma system with drifting ions. It is reported that in the presence of drifting ions with drift speed exceeding the ion acoustic wave speed, the electron inertial delay effect facilitates the resonance coupling of the usual fluid ion acoustic mode with the ion-beam mode. In this contribution the same instability is analyzed by graphical and numerical methods. This is to note that the obtained dispersion relation differs from those of the other known normal modes of low frequency ion plasma oscillations and waves. This is due to consideration of electron inertial delay in derivation of the dispersion relation of the ion acoustic wave fluctuations. Numerical calculations of the dispersion relation and wave energy are carried out to depict the graphical appearance of poles and positive-negative enegy modes. It is found that the electron inertia induced ion acoustic wave instability arises out of linear resonance coupling between the negative and positive energy modes. Characterization of the resonance nature of the instability in Mach number space for different wave numbers of the ion acoustic mode is presented.

  7. A comparative analysis of acoustic energy models for churches.

    PubMed

    Berardi, Umberto; Cirillo, Ettore; Martellotta, Francesco

    2009-10-01

    Different models to improve prediction of energy-based acoustic parameters in churches have been proposed by different researchers [E. Cirillo and F. Martellotta, J. Acoust. Soc. Am. 118, 232-248 (2005); T. Zamarreño et al., J. Acoust. Soc. Am. 121, 234-250 (2006)]. They all suggested variations to the "revised" theory proposed by Barron and Lee [J. Acoust. Soc. Am. 84, 618-628 (1988)], starting from experimental observations. The present paper compares these models and attempts to generalize their use taking advantage of the measurements carried out in 24 Italian churches differing in style, typology, and location. The whole sample of churches was divided into two groups. The first was used to fine-tune existing models, with particular reference to the "mu model," which was originally tested only on Mudejar-Gothic churches. Correlations between model parameters and major typological and architectural factors were found, leading to a classification that greatly simplifies parameter choice. Finally, the reliability of each model was verified on the rest of the sample, showing that acoustic parameters can be predicted with reasonable accuracy provided that one of the specifically modified theories is used. The results show that the model requiring more input parameters performs slightly better than the other which, conversely, is simpler to apply. PMID:19813798

  8. A probability density function method for acoustic field uncertainty analysis

    NASA Astrophysics Data System (ADS)

    James, Kevin R.; Dowling, David R.

    2005-11-01

    Acoustic field predictions, whether analytical or computational, rely on knowledge of the environmental, boundary, and initial conditions. When knowledge of these conditions is uncertain, acoustic field predictions will also be uncertain, even if the techniques for field prediction are perfect. Quantifying acoustic field uncertainty is important for applications that require accurate field amplitude and phase predictions, like matched-field techniques for sonar, nondestructive evaluation, bio-medical ultrasound, and atmospheric remote sensing. Drawing on prior turbulence research, this paper describes how an evolution equation for the probability density function (PDF) of the predicted acoustic field can be derived and used to quantify predicted-acoustic-field uncertainties arising from uncertain environmental, boundary, or initial conditions. Example calculations are presented in one and two spatial dimensions for the one-point PDF for the real and imaginary parts of a harmonic field, and show that predicted field uncertainty increases with increasing range and frequency. In particular, at 500 Hz in an ideal 100 m deep underwater sound channel with a 1 m root-mean-square depth uncertainty, the PDF results presented here indicate that at a range of 5 km, all phases and a 10 dB range of amplitudes will have non-negligible probability. Evolution equations for the two-point PDF are also derived.

  9. On the vibro-acoustical operational modal analysis of a helicopter cabin

    NASA Astrophysics Data System (ADS)

    Pierro, E.; Mucchi, E.; Soria, L.; Vecchio, A.

    2009-05-01

    This paper aims to present a modal decomposition formulation for a vibro-acoustical operational modal analysis (OMA). In literature many works can be found on this topic, but until now no attention has been focused on the analytical form of the cross-power spectra (CPs) between the system outputs when a fluid-structure coupling is present. In this work it is shown that the CPs modal decomposition depends on the choice of the references, i.e. acoustical or structural. At first it is theoretically pointed out that the CP formulation for the acoustical and structural case is formally identical if appropriately pre-processed. Then, this theoretical result is verified through the results of an extensive experimental testing on the helicopter EUROCOPTER EC-135. The CPs between the structural output velocities and the acoustical response of the microphone inside the helicopter cabin are considered as inputs of an OMA. In order to verify the effectiveness of the modal model so obtained a classical modal analysis is also performed. The acoustical reference choice reveals to be suitable for a vibro-acoustical OMA. It is highlighted, indeed, that the acoustical pressure measurement inside the enclosure can be used as reference instead of the commonly used structural sensors, both from the theoretical and practical point of view. This is useful for high scale structures where the structural responses are usually measured by means of moving sensor arrays and additional fixed reference sensors should be positioned on the surface.

  10. Application of an Aligned and Unaligned Signal Processing Technique to Investigate Tones and Broadband Noise in Fan and Contra-Rotating Open Rotor Acoustic Spectra

    NASA Technical Reports Server (NTRS)

    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.

  11. Acoustic-Seismic Coupling in Porous Ground - Measurements and Analysis for On-Site-Inspection Support

    NASA Astrophysics Data System (ADS)

    Liebsch, Mattes; Gorschlüter, Felix; Altmann, Jürgen

    2014-05-01

    During on-site inspections (OSI) of the Comprehensive Nuclear Test Ban Treaty Organisation (CTBTO) a local seismic network can be installed to measure seismic aftershock signals of an assumed underground nuclear explosion. These signals are caused by relaxation processes in and near the cavity created by the explosion and when detected can lead to a localisation of the cavity. This localisation is necessary to take gas samples from the ground which are analysed for radioactive noble gas isotopes to confirm or dismiss the suspicion of a nuclear test. The aftershock signals are of very low magnitude so they can be masked by different sources, in particular periodic disturbances caused by vehicles and aircraft in the inspection area. Vehicles and aircraft (mainly helicopters) will be used for the inspection activities themselves, e.g. for overhead imagery or magnetic-anomaly sensing. While vehicles in contact with the ground can excite soil vibrations directly, aircraft and vehicles alike emit acoustic waves which excite soil vibrations when hitting the ground. These disturbing signals are of periodic nature while the seismic aftershock signals are pulse-shaped, so their separation is possible. The understanding of the coupling of acoustic waves to the ground is yet incomplete, a better understanding is necessary to improve the performance of an OSI, e.g. to address potential consequences for the sensor placement, the helicopter trajectories etc. In a project funded by the Young Scientist Research Award of the CTBTO to one of us (ML), we investigated the acoustic-seismic coupling of airborne signals of jet aircraft and artificially induced ones by a speaker. During a measurement campaign several acoustic and seismic sensors were placed below the take-off trajectory of an airport at 4 km distance. Therefore taking off and landing jet aircraft passed nearly straightly above the setup. Microphones were placed close to the ground to record the sound pressure of incident

  12. Overview on the Diversity of Sounds Produced by Clownfishes (Pomacentridae): Importance of Acoustic Signals in Their Peculiar Way of Life

    PubMed Central

    Colleye, Orphal; Parmentier, Eric

    2012-01-01

    Background Clownfishes (Pomacentridae) are brightly colored coral reef fishes well known for their mutualistic symbiosis with tropical sea anemones. These fishes live in social groups in which there is a size-based dominance hierarchy. In this structure where sex is socially controlled, agonistic interactions are numerous and serve to maintain size differences between individuals adjacent in rank. Clownfishes are also prolific callers whose sounds seem to play an important role in the social hierarchy. Here, we aim to review and to synthesize the diversity of sounds produced by clownfishes in order to emphasize the importance of acoustic signals in their way of life. Methodology/Principal Findings Recording the different acoustic behaviors indicated that sounds are divided into two main categories: aggressive sounds produced in conjunction with threat postures (charge and chase), and submissive sounds always emitted when fish exhibited head shaking movements (i.e. a submissive posture). Both types of sounds showed size-related intraspecific variation in dominant frequency and pulse duration: smaller individuals produce higher frequency and shorter duration pulses than larger ones, and inversely. Consequently, these sonic features might be useful cues for individual recognition within the group. This observation is of significant importance due to the size-based hierarchy in clownfish group. On the other hand, no acoustic signal was associated with the different reproductive activities. Conclusions/Significance Unlike other pomacentrids, sounds are not produced for mate attraction in clownfishes but to reach and to defend the competition for breeding status, which explains why constraints are not important enough for promoting call diversification in this group. PMID:23145114

  13. An acoustical analysis of a room with a concave dome ceiling element

    NASA Astrophysics Data System (ADS)

    Utami, Sentagi S.

    2001-05-01

    Concave surfaces are often considered detrimental in room acoustics, especially because of the impact they have on the distribution of sound energy. This paper explores certain acoustical characteristics and anomalies found in spaces below concave dome ceiling elements. The architectural design of the Darusshollah mosque in East Java, Indonesia is used as a case study with specific spatial and functional concerns. Investigations of the mosque have been conducted through both a 1:12 scale model and a computer model that utilizes ray tracing and image source methods. Analysis techniques are discussed. Results are presented and compared to provide useful insights into the acoustics of such distinctive environments.

  14. Analysis of Particle Image Velocimetry (PIV) Data for Acoustic Velocity Measurements

    NASA Technical Reports Server (NTRS)

    Blackshire, James L.

    1997-01-01

    Acoustic velocity measurements were taken using Particle Image Velocimetry (PIV) in a Normal Incidence Tube configuration at various frequency, phase, and amplitude levels. This report presents the results of the PIV analysis and data reduction portions of the test and details the processing that was done. Estimates of lower measurement sensitivity levels were determined based on PIV image quality, correlation, and noise level parameters used in the test. Comparison of measurements with linear acoustic theory are presented. The onset of nonlinear, harmonic frequency acoustic levels were also studied for various decibel and frequency levels ranging from 90 to 132 dB and 500 to 3000 Hz, respectively.

  15. Underwater Acoustics

    NASA Astrophysics Data System (ADS)

    Kuperman, William A.; Roux, Philippe

    It is well underwater established that sound waves, compared to electromagnetic waves, propagate long distances in the ocean. Hence, in the ocean as opposed to air or a vacuum, one uses sound navigation and ranging (SONAR) instead navigation and ranging (SONAR) of radar, acoustic communication instead of radio, and acoustic imaging and tomography instead of microwave or optical imaging or X-ray tomography. Underwater acoustics is the science of sound in water (most commonly in the ocean) and encompasses not only the study of sound propagation, but also the masking of sound signals by interfering phenomenon and signal processing for extracting these signals from interference. This chapter we will present the basics physics of ocean acoustics and then discuss applications.

  16. Observations and Bayesian location methodology of transient acoustic signals (likely blue whales) in the Indian Ocean, using a hydrophone triplet.

    PubMed

    Le Bras, Ronan J; Kuzma, Heidi; Sucic, Victor; Bokelmann, Götz

    2016-05-01

    A notable sequence of calls was encountered, spanning several days in January 2003, in the central part of the Indian Ocean on a hydrophone triplet recording acoustic data at a 250 Hz sampling rate. This paper presents signal processing methods applied to the waveform data to detect, group, extract amplitude and bearing estimates for the recorded signals. An approximate location for the source of the sequence of calls is inferred from extracting the features from the waveform. As the source approaches the hydrophone triplet, the source level (SL) of the calls is estimated at 187 ± 6 dB re: 1 μPa-1 m in the 15-60 Hz frequency range. The calls are attributed to a subgroup of blue whales, Balaenoptera musculus, with a characteristic acoustic signature. A Bayesian location method using probabilistic models for bearing and amplitude is demonstrated on the calls sequence. The method is applied to the case of detection at a single triad of hydrophones and results in a probability distribution map for the origin of the calls. It can be extended to detections at multiple triads and because of the Bayesian formulation, additional modeling complexity can be built-in as needed. PMID:27250159

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  18. Visualizing detecting low-frequency underwater acoustic signals by means of optical diffraction.

    PubMed

    Ren, Yao; Miao, Runcai; Su, Xiaoming; Chen, Hua

    2016-03-10

    A novel and simple technique based on the light diffraction effect for visualization of low-frequency underwater acoustic waves (LFUAWs) in real time has been developed in this paper. A cylindrical object has been put on the surface of the water. A low-frequency underwater longitudinal wave can be generated into a water surface transversal capillary wave around the cylinder by our technique. Modulating the phase of a laser beam reflected from a water surface by surface acoustic waves (SAWs) realizes the acousto-optic effect. Then, a steady and visible diffraction pattern is experimentally observed. A physical model of the SAW is established to verify the feasibility of our technique. An analytical expression of wavelength, wave amplitude, and excitation frequency has been derived to study the physical properties of LFUAWs, and it explains the experimental phenomenon very well. As a result, the technique is effective, easy, and practical for visualizing LFUAWs and has significance for applications. PMID:26974797

  19. Estimation of crack and damage progression in concrete by quantitative acoustic emission analysis

    SciTech Connect

    Ohtsu, Masayasu

    1999-05-01

    The kinematics of cracking can be represented by the moment tensor. To distinguish moment tensor components from acoustic emission waveforms, the SiGMA (simplified Green`s functions for moment tensor analysis) procedure was developed. By applying the procedure to bending tests of notched beams, cracks in the fracture process zone of cementitious materials can be identified by kinematic means. In addition to cracks, estimation of the damage level in structural concrete is also conducted, based on acoustic emission activity of a concrete sample under compression. Depending on the damage resulting from existing microcracks, acoustic emission generated behavior is quantitatively estimated by the rate process analysis. The damage mechanics are introduced to quantify the degree of damage. Determining the current damage level using acoustic emission without information on undamaged concrete is attempted by correlating the damage value with the rate process.

  20. The ionospheric response to the acoustic signal from submarine earthquakes according to the GPS data

    NASA Astrophysics Data System (ADS)

    Gokhberg, M. B.; Ol'shanskaya, E. V.; Steblov, G. M.; Shalimov, S. L.

    2014-01-01

    The ionospheric response to the transit of acoustic waves from a number of the strongest submarine earthquakes with magnitudes M w ≥ 7.7, which occurred during the past few years, is analyzed. The amplitude of the response in the detrended TEC is studied as a function of the magnitude and vertical component of the surface deformation. It is shown that the geomagnetic field can significantly modulate the shape of the ionospheric response, depending on whether the perturbation propagates equatorward or polarward.

  1. Identification of vibration excitations from acoustic measurements using near field acoustic holography and the force analysis technique

    NASA Astrophysics Data System (ADS)

    Pézerat, C.; Leclère, Q.; Totaro, N.; Pachebat, M.

    2009-10-01

    This study presents a method of using acoustic holography and the force analysis technique to identify vibration sources from radiated noise measurements. The structure studied is a plate excited by a shaker on which three measurements were performed: the first is a reference measurement of plate velocity obtained by scanning laser vibrometry, the second is based on sound pressure measurements in the near field of the structure, and the third is the measurement of normal acoustic velocities by using a p-U probe recently developed by Microflown Technologies. This was followed by the application of classical NAH, known as pressure-to-velocity holography and velocity-to-velocity holography to predict the plate velocity field from acoustic measurements at distances of 1 and 5 cm. Afterwards, the force analysis technique, also known as the RIFF technique, is applied with these five data sets. The principle is to inject the displacement field of the structure into its equation of motion and extract the resulting force distribution. This technique requires regularization done by a low-pass filter in the wavenumber domain. Apart from pressure-to-velocity holography at 5 cm, the reconstructed force distribution allows localizing the excitation point in the measurement area. FAT regularization is also shown to improve results as its cutoff wavenumber is optimized with the natural wavenumber of the plate. Lastly, quantitative force values are extracted from force distributions at all frequencies of the band 0-4 kHz studied and compared with the force spectrum measured directly by a piezoelectric sensor.

  2. Auditory object salience: human cortical processing of non-biological action sounds and their acoustic signal attributes

    PubMed Central

    Lewis, James W.; Talkington, William J.; Tallaksen, Katherine C.; Frum, Chris A.

    2012-01-01

    Whether viewed or heard, an object in action can be segmented as a distinct salient event based on a number of different sensory cues. In the visual system, several low-level attributes of an image are processed along parallel hierarchies, involving intermediate stages wherein gross-level object form and/or motion features are extracted prior to stages that show greater specificity for different object categories (e.g., people, buildings, or tools). In the auditory system, though relying on a rather different set of low-level signal attributes, meaningful real-world acoustic events and “auditory objects” can also be readily distinguished from background scenes. However, the nature of the acoustic signal attributes or gross-level perceptual features that may be explicitly processed along intermediate cortical processing stages remain poorly understood. Examining mechanical and environmental action sounds, representing two distinct non-biological categories of action sources, we had participants assess the degree to which each sound was perceived as object-like versus scene-like. We re-analyzed data from two of our earlier functional magnetic resonance imaging (fMRI) task paradigms (Engel et al., 2009) and found that scene-like action sounds preferentially led to activation along several midline cortical structures, but with strong dependence on listening task demands. In contrast, bilateral foci along the superior temporal gyri (STG) showed parametrically increasing activation to action sounds rated as more “object-like,” independent of sound category or task demands. Moreover, these STG regions also showed parametric sensitivity to spectral structure variations (SSVs) of the action sounds—a quantitative measure of change in entropy of the acoustic signals over time—and the right STG additionally showed parametric sensitivity to measures of mean entropy and harmonic content of the environmental sounds. Analogous to the visual system, intermediate stages

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

    SciTech Connect

    Vivek Agarwal; Magdy Samy Tawfik; James A Smith

    2014-07-01

    Existing and developing advanced sensor technologies and instrumentation will allow non-intrusive in-pile measurement of temperature, extension, and fission gases when coupled with advanced signal processing algorithms. The transmitted measured sensor signals from inside to the outside of containment structure are corrupted by noise and are attenuated, thereby reducing the signal strength and signal-to-noise ratio. Identification and extraction of actual signal (representative of an in-pile phenomenon) is a challenging and complicated process. In this paper, empirical mode decomposition technique is proposed to reconstruct actual sensor signal by partially combining intrinsic mode functions. Reconstructed signal corresponds to phenomena and/or failure modes occurring inside the reactor. In addition, it allows accurate non-intrusive monitoring and trending of in-pile phenomena.

  4. Acoustic emission signal processing technique to characterize reactor in-pile phenomena

    SciTech Connect

    Agarwal, Vivek; Tawfik, Magdy S.; Smith, James A.

    2015-03-31

    Existing and developing advanced sensor technologies and instrumentation will allow non-intrusive in-pile measurement of temperature, extension, and fission gases when coupled with advanced signal processing algorithms. The transmitted measured sensor signals from inside to the outside of containment structure are corrupted by noise and are attenuated, thereby reducing the signal strength and the signal-to-noise ratio. Identification and extraction of actual signal (representative of an in-pile phenomenon) is a challenging and complicated process. In the paper, empirical mode decomposition technique is utilized to reconstruct actual sensor signal by partially combining intrinsic mode functions. Reconstructed signal will correspond to phenomena and/or failure modes occurring inside the reactor. In addition, it allows accurate non-intrusive monitoring and trending of in-pile phenomena.

  5. Dynamical energy analysis for built-up acoustic systems at high frequencies.

    PubMed

    Chappell, D J; Giani, S; Tanner, G

    2011-09-01

    Standard methods for describing the intensity distribution of mechanical and acoustic wave fields in the high frequency asymptotic limit are often based on flow transport equations. Common techniques are statistical energy analysis, employed mostly in the context of vibro-acoustics, and ray tracing, a popular tool in architectural acoustics. Dynamical energy analysis makes it possible to interpolate between standard statistical energy analysis and full ray tracing, containing both of these methods as limiting cases. In this work a version of dynamical energy analysis based on a Chebyshev basis expansion of the Perron-Frobenius operator governing the ray dynamics is introduced. It is shown that the technique can efficiently deal with multi-component systems overcoming typical geometrical limitations present in statistical energy analysis. Results are compared with state-of-the-art hp-adaptive discontinuous Galerkin finite element simulations. PMID:21895083

  6. Genomic signal analysis of pathogen variability

    NASA Astrophysics Data System (ADS)

    Cristea, Paul Dan

    2006-02-01

    The paper presents results in the study of pathogen variability by using genomic signals. The conversion of symbolic nucleotide sequences into digital signals offers the possibility to apply signal processing methods to the analysis of genomic data. The method is particularly well suited to characterize small size genomic sequences, such as those found in viruses and bacteria, being a promising tool in tracking the variability of pathogens, especially in the context of developing drug resistance. The paper is based on data downloaded from GenBank [32], and comprises results on the variability of the eight segments of the influenza type A, subtype H5N1, virus genome, and of the Hemagglutinin (HA) gene, for the H1, H2, H3, H4, H5 and H16 types. Data from human and avian virus isolates are used.

  7. Phosphor thermometry signal analysis and interpretation

    NASA Astrophysics Data System (ADS)

    Allison, S. W.; Gillies, G. T.

    2013-09-01

    Since the last International Temperature Symposium, phosphor thermometry has continued to mature with considerable attention given to combustion and turbine engine applications. More recently the utility to problems on the micro-and nano-scales has appreciated, particularly in regard to biological and biomedical situations. The method is therefore used for a wide range of situations. Signal interpretation is important and experience teaches that without sufficient care phosphor signals can be misleading. In order to advance the method, signal analysis investigations should prove fruitful. The specific aspect addressed here is the question of waveform sampling. A simple phenomenological approach is described that explores how the number of points digitized per waveform affects the measurement repeatability and accuracy. This is demonstrated for single shot signals and the average of 512 sequential waveforms. A bright temperature-independent luminescence signal from YVO4:Eu is sampled every 800 ps (1.25 GS/s) for a highly sampled condition and every 8 microseconds (125 kS/s) for a low sampled condition. When the average of 512 waveforms are compared for the two sampling conditions, they differ by only 0.4%. For the highly sampled case, a noisy single shot waveform compared to the averaged waveform differed by 1.8%. Future efforts on this subject will address intermediate and lower sampling rates. Also, variable window techniques should be explored that are especially important for non-log-linear signals. Investigations, such as this, give the developer the requisite information for designing analysis systems appropriate for the intended application in terms of precision, accuracy, and response time.

  8. Phosphor Thermometry Signal Analysis and Interpretation

    SciTech Connect

    Allison, Stephen W; Gillies, George T.

    2013-01-01

    Since the last International Temperature Symposium, phosphor thermometry has continued to mature with considerable attention given to combustion and turbine engine applications. More recently the utility to problems on the micro- and nano-scales has appreciated, particularly in regard to biological and biomedical situations. The method is therefore used for a wide range of situations. Signal interpretation is important and experience teaches that without sufficient care phosphor signals can be misleading. In order to advance the method, signal analysis investigations should prove fruitful. The specific aspect addressed here is the question of waveform sampling. A simple phenomenological approach is described that explores how the number of points digitized per waveform affects the measurement repeatability and accuracy. This is demonstrated for single shot signals and the average of 512 sequential waveforms. A bright temperature-independent luminescence signal from YVO4:Eu is sampled every 800 ps for a highly sampled condition and every 8 microseconds for a low sampled condition. When the average of 512 waveforms are compared for the two sampling conditions, they differ by only 0.4%. For the highly sampled case, a noisy single shot waveform compared to the averaged waveform differed by 1.8%. Future efforts on this subject will address intermediate and lower sampling rates. Also, variable window techniques should be explored that are especially important for non-log-linear signals. Investigations, such as this, give the developer the requisite information for designing analysis systems appropriate for the intended application in terms of precision, accuracy, and response time.

  9. Acoustic analysis of the interaction of choral arrangements, musical selection, and microphone location.

    PubMed

    Morris, Richard J; Mustafa, Ashley J; McCrea, Christopher R; Fowler, Linda P; Aspaas, Christopher

    2007-09-01

    Acoustic differences were evaluated among three choral arrangements and two choral textures recorded at three microphone locations. A choir was recorded when singing two musical selections of different choral texture, one homophonic and one polyphonic. Both musical selections were sung in three choral arrangements: block sectional, sectional-in-columns, and mixed. Microphones were placed at the level of the choristers, the conductor, and the audience. The recordings at each location were analyzed using long-term average spectrum (LTAS). The LTAS from the mixed arrangement exhibited more signal amplitude than the other arrangements in the range of 1000-3500Hz. When considering the musical selections, the chorus produced more signal amplitude in the region of 1800-2200Hz for the homophonic selection. In addition, the LTAS produced by the choir for the homophonic selection varied across the microphone locations. As for the microphone location, the LTAS of the signal detected directly in front of the chorus had a greater slope than the other two locations. Thus, the acoustic signal near the choristers differed from the signals near the conductor and in the audience. Conductors may be using acoustic information from the region of the second and third formants when they decide how to arrange a choir for a particular musical selection. PMID:16806816

  10. Selective and Efficient Neural Coding of Communication Signals Depends on Early Acoustic and Social Environment

    PubMed Central

    Amin, Noopur; Gastpar, Michael; Theunissen, Frédéric E.

    2013-01-01

    Previous research has shown that postnatal exposure to simple, synthetic sounds can affect the sound representation in the auditory cortex as reflected by changes in the tonotopic map or other relatively simple tuning properties, such as AM tuning. However, their functional implications for neural processing in the generation of ethologically-based perception remain unexplored. Here we examined the effects of noise-rearing and social isolation on the neural processing of communication sounds such as species-specific song, in the primary auditory cortex analog of adult zebra finches. Our electrophysiological recordings reveal that neural tuning to simple frequency-based synthetic sounds is initially established in all the laminae independent of patterned acoustic experience; however, we provide the first evidence that early exposure to patterned sound statistics, such as those found in native sounds, is required for the subsequent emergence of neural selectivity for complex vocalizations and for shaping neural spiking precision in superficial and deep cortical laminae, and for creating efficient neural representations of song and a less redundant ensemble code in all the laminae. Our study also provides the first causal evidence for ‘sparse coding’, such that when the statistics of the stimuli were changed during rearing, as in noise-rearing, that the sparse or optimal representation for species-specific vocalizations disappeared. Taken together, these results imply that a layer-specific differential development of the auditory cortex requires patterned acoustic input, and a specialized and robust sensory representation of complex communication sounds in the auditory cortex requires a rich acoustic and social environment. PMID:23630587

  11. Acoustic communication by ants

    NASA Astrophysics Data System (ADS)

    Hickling, Robert

    2002-05-01

    Many ant species communicate acoustically by stridulating, i.e., running a scraper over a washboard-like set of ridges. Ants appear to be insensitive to airborne sound. Consequently, myrmecologists have concluded that the stridulatory signals are transmitted through the substrate. This has tended to diminish the importance of acoustic communication, and it is currently believed that ant communication is based almost exclusively on pheromones, with acoustic communication assigned an almost nonexistent role. However, it can be shown that acoustic communication between ants is effective only if the medium is air and not the substrate. How, then, is it possible for ants to appear deaf to airborne sound and yet communicate through the air? An explanation is provided in a paper [R. Hickling and R. L. Brown, ``Analysis of acoustic communication by ants,'' J. Acoust. Soc. Am. 108, 1920-1929 (2000)]. Ants are small relative to the wavelengths they generate. Hence, they create a near field, which is characterized by a major increase in sound velocity (particle velocity of sound) in the vicinity of the source. Hair sensilla on the ants' antennae respond to sound velocity. Thus, ants are able to detect near-field sound from other ants and to exclude extraneous airborne sound.

  12. Acoustic detection of pneumothorax

    NASA Astrophysics Data System (ADS)

    Mansy, Hansen A.; Royston, Thomas J.; Balk, Robert A.; Sandler, Richard H.

    2003-04-01

    This study aims at investigating the feasibility of using low-frequency (<2000 Hz) acoustic methods for medical diagnosis. Several candidate methods of pneumothorax detection were tested in dogs. In the first approach, broadband acoustic signals were introduced into the trachea during end-expiration and transmitted waves were measured at the chest surface. Pneumothorax was found to consistently decrease pulmonary acoustic transmission in the 200-1200-Hz frequency band, while less change was observed at lower frequencies (p<0.0001). The ratio of acoustic energy between low (<220 Hz) and mid (550-770 Hz) frequency bands was significantly different in the control (healthy) and pneumothorax states (p<0.0001). The second approach measured breath sounds in the absence of an external acoustic input. Pneumothorax was found to be associated with a preferential reduction of sound amplitude in the 200- to 700-Hz range, and a decrease of sound amplitude variation (in the 300 to 600-Hz band) during the respiration cycle (p<0.01 for each). Finally, chest percussion was implemented. Pneumothorax changed the frequency and decay rate of percussive sounds. These results imply that certain medical conditions may be reliably detected using appropriate acoustic measurements and analysis. [Work supported by NIH/NHLBI #R44HL61108.

  13. Body Morphology, Energy Stores, and Muscle Enzyme Activity Explain Cricket Acoustic Mate Attraction Signaling Variation

    PubMed Central

    Thomson, Ian R.; Darveau, Charles-A.; Bertram, Susan M.

    2014-01-01

    High mating success in animals is often dependent on males signalling attractively with high effort. Since males should be selected to maximize their reproductive success, female preferences for these traits should result in minimal signal variation persisting in the population. However, extensive signal variation persists. The genic capture hypothesis proposes genetic variation persists because fitness-conferring traits depend on an individual's basic processes, including underlying physiological, morphological, and biochemical traits, which are themselves genetically variable. To explore the traits underlying signal variation, we quantified among-male differences in signalling, morphology, energy stores, and the activities of key enzymes associated with signalling muscle metabolism in two species of crickets, Gryllus assimilis (chirper: <20 pulses/chirp) and G. texensis (triller: >20 pulses/chirp). Chirping G. assimilis primarily fuelled signalling with carbohydrate metabolism: smaller individuals and individuals with increased thoracic glycogen stores signalled for mates with greater effort; individuals with greater glycogen phosphorylase activity produced more attractive mating signals. Conversely, the more energetic trilling G. texensis fuelled signalling with both lipid and carbohydrate metabolism: individuals with increased β-hydroxyacyl-CoA dehydrogenase activity and increased thoracic free carbohydrate content signalled for mates with greater effort; individuals with higher thoracic and abdominal carbohydrate content and higher abdominal lipid stores produced more attractive signals. Our findings suggest variation in male reproductive success may be driven by hidden physiological trade-offs that affect the ability to uptake, retain, and use essential nutrients, although the results remain correlational in nature. Our findings indicate that a physiological perspective may help us to understand some of the causes of variation in behaviour. PMID:24608102

  14. Distribution entropy analysis of epileptic EEG signals.

    PubMed

    Li, Peng; Yan, Chang; Karmakar, Chandan; Liu, Changchun

    2015-08-01

    It is an open-ended challenge to accurately detect the epileptic seizures through electroencephalogram (EEG) signals. Recently published studies have made elaborate attempts to distinguish between the normal and epileptic EEG signals by advanced nonlinear entropy methods, such as the approximate entropy, sample entropy, fuzzy entropy, and permutation entropy, etc. Most recently, a novel distribution entropy (DistEn) has been reported to have superior performance compared with the conventional entropy methods for especially short length data. We thus aimed, in the present study, to show the potential of DistEn in the analysis of epileptic EEG signals. The publicly-accessible Bonn database which consisted of normal, interictal, and ictal EEG signals was used in this study. Three different measurement protocols were set for better understanding the performance of DistEn, which are: i) calculate the DistEn of a specific EEG signal using the full recording; ii) calculate the DistEn by averaging the results for all its possible non-overlapped 5 second segments; and iii) calculate it by averaging the DistEn values for all the possible non-overlapped segments of 1 second length, respectively. Results for all three protocols indicated a statistically significantly increased DistEn for the ictal class compared with both the normal and interictal classes. Besides, the results obtained under the third protocol, which only used very short segments (1 s) of EEG recordings showed a significantly (p <; 0.05) increased DistEn for the interictal class in compassion with the normal class, whereas both analyses using relatively long EEG signals failed in tracking this difference between them, which may be due to a nonstationarity effect on entropy algorithm. The capability of discriminating between the normal and interictal EEG signals is of great clinical relevance since it may provide helpful tools for the detection of a seizure onset. Therefore, our study suggests that the Dist

  15. Apparatus for statistical time-series analysis of electrical signals

    NASA Technical Reports Server (NTRS)

    Stewart, C. H. (Inventor)

    1973-01-01

    An apparatus for performing statistical time-series analysis of complex electrical signal waveforms, permitting prompt and accurate determination of statistical characteristics of the signal is presented.

  16. Property evaluation of thermal sprayed metallic coating by acoustic emission analysis

    SciTech Connect

    Ishida, Asako; Mizutani, Yoshihiro; Takemoto, Mikio; Ono, Kanji

    2000-03-01

    The authors analyzed acoustic emission signals from plasma sprayed sheets by first obtaining the Young's modulus, Poisson's ratio, and density. The sheets of a high Cr-Ni alloy (55Cr-41Ni-Mo, Si, B) were made by low pressure plasma spraying (LPPS) and heat treated. Utilizing laser induced surface acoustic waves (SAWs), the group velocity dispersion data of Rayleigh waves was obtained and matched to that computed by Adler's matrix transfer method. They monitored the acoustic emissions (Lamb waves) produced by microfractures in free standing as sprayed coating subjected to bending. Fast cleavage type microfracture with source rise time of around 2 {micro}s occurred as precursors to the final brittle fracture. The velocity and time-frequency amplitude spectrograms (wavelet contour maps) of the Lamb waves were utilized for the source location and fracture kinetic analyses.

  17. Analysis of the acoustic response in water and sand of different fiber optic sensing cables

    NASA Astrophysics Data System (ADS)

    Hofmann, Joachim; Facchini, Massimo; Lowell, Mark

    2015-05-01

    Distributed Acoustic Sensing (DAS) is a highly promising technology to efficiently monitor assets for energy production and transportation, both off- and on-shore, such as boreholes, pipelines and risers. The aim of the hereby-presented measurements is to evaluate the sensitivity of the different optical fiber cables to acoustic signals in sand and water, independently from the DAS read-out unit type and manufacturer. Acoustic sensing cables specifically designed by BRUGG Cables are characterized and compared to standard telecommunication cables. The spectral response of each cable was quantified using an all-fiber Mach-Zehnder interferometer. The response was also measured with calibrated microphones in order to convert the measurements into absolute physical units (Pascal). The measurement campaign is part of an investigation program for a reliable DAS system, which comprises the sensing cable (including installation procedure), the interrogator unit and suitable software.

  18. Gait Signal Analysis with Similarity Measure

    PubMed Central

    Shin, Seungsoo

    2014-01-01

    Human gait decision was carried out with the help of similarity measure design. Gait signal was selected through hardware implementation including all in one sensor, control unit, and notebook with connector. Each gait signal was considered as high dimensional data. Therefore, high dimensional data analysis was considered via heuristic technique such as the similarity measure. Each human pattern such as walking, sitting, standing, and stepping up was obtained through experiment. By the results of the analysis, we also identified the overlapped and nonoverlapped data relation, and similarity measure analysis was also illustrated, and comparison with conventional similarity measure was also carried out. Hence, nonoverlapped data similarity analysis provided the clue to solve the similarity of high dimensional data. Considered high dimensional data analysis was designed with consideration of neighborhood information. Proposed similarity measure was applied to identify the behavior patterns of different persons, and different behaviours of the same person. Obtained analysis can be extended to organize health monitoring system for specially elderly persons. PMID:25110724

  19. Acoustic Inspection and Analysis of Liquids in Sealed Containers

    SciTech Connect

    Diaz, Aaron A.

    2003-12-01

    This article describes the Acoustic Inspection Device (AID) developed by PNNL which uses acoustic to determine the contents and fill level of sealed containers. AID is a power drill shaped battery operated device fitted with a transducer that sends an ultrasonic pusle through a container of liquid and measure the return echo. The device compares the echo velocity and attnuation and compares that data to a materials database in an Palm Pilot vlecored to the top of the device to give the operator a text identification of the substance with 5 seconds. The device is sensitive enough to distinguish coke from diet coke and and can distinguish subtances at a variety of temperatures ranging from below freezing to over 100degreesF. PNNL won an R&D 100 award for the technology in 2003.

  20. An iterative algorithm for analysis of coupled structural-acoustic systems subject to random excitations

    NASA Astrophysics Data System (ADS)

    Zhao, Guo-Zhong; Chen, Gang; Kang, Zhan

    2012-04-01

    This paper analyzes the random response of structural-acoustic coupled systems. Most existing works on coupled structural-acoustic analysis are limited to systems under deterministic excitations due to high computational cost required by a random response analysis. To reduce the computational burden involved in the coupled random analysis, an iterative procedure based on the Pseudo excitation method has been developed. It is found that this algorithm has an overwhelming advantage in computing efficiency over traditional methods, as demonstrated by some numerical examples given in this paper.

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

    NASA Technical Reports Server (NTRS)

    Hines, Jacqueline H. (Inventor)

    2015-01-01

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

  2. Analysis of Acoustic Features in Speakers with Cognitive Disorders and Speech Impairments

    NASA Astrophysics Data System (ADS)

    Saz, Oscar; Simón, Javier; Rodríguez, W. Ricardo; Lleida, Eduardo; Vaquero, Carlos

    2009-12-01

    This work presents the results in the analysis of the acoustic features (formants and the three suprasegmental features: tone, intensity and duration) of the vowel production in a group of 14 young speakers suffering different kinds of speech impairments due to physical and cognitive disorders. A corpus with unimpaired children's speech is used to determine the reference values for these features in speakers without any kind of speech impairment within the same domain of the impaired speakers; this is 57 isolated words. The signal processing to extract the formant and pitch values is based on a Linear Prediction Coefficients (LPCs) analysis of the segments considered as vowels in a Hidden Markov Model (HMM) based Viterbi forced alignment. Intensity and duration are also based in the outcome of the automated segmentation. As main conclusion of the work, it is shown that intelligibility of the vowel production is lowered in impaired speakers even when the vowel is perceived as correct by human labelers. The decrease in intelligibility is due to a 30% of increase in confusability in the formants map, a reduction of 50% in the discriminative power in energy between stressed and unstressed vowels and to a 50% increase of the standard deviation in the length of the vowels. On the other hand, impaired speakers keep good control of tone in the production of stressed and unstressed vowels.

  3. Genomic signal analysis of Mycobacterium tuberculosis

    NASA Astrophysics Data System (ADS)

    Cristea, Paul Dan; Banica, Dorina; Tuduce, Rodica

    2007-02-01

    As previously shown the conversion of nucleotide sequences into digital signals offers the possibility to apply signal processing methods for the analysis of genomic data. Genomic Signal Analysis (GSA) has been used to analyze large scale features of DNA sequences, at the scale of whole chromosomes, including both coding and non-coding regions. The striking regularities of genomic signals reveal restrictions in the way nucleotides and pairs of nucleotides are distributed along nucleotide sequences. Structurally, a chromosome appears to be less of a "plain text", corresponding to certain semantic and grammar rules, but more of a "poem", satisfying additional symmetry restrictions that evoke the "rhythm" and "rhyme". Recurrent patterns in nucleotide sequences are reflected in simple mathematical regularities observed in genomic signals. GSA has also been used to track pathogen variability, especially concerning their resistance to drugs. Previous work has been dedicated to the study of HIV-1, Clade F and Avian Flu. The present paper applies GSA methodology to study Mycobacterium tuberculosis (MT) rpoB gene variability, relevant to its resistance to antibiotics. Isolates from 50 Romanian patients have been studied both by rapid LightCycler PCR and by sequencing of a segment of 190-250 nucleotides covering the region of interest. The variability is caused by SNPs occurring at specific sites along the gene strand, as well as by inclusions. Because of the mentioned symmetry restrictions, the GS variations tend to compensate. An important result is that MT can act as a vector for HIV virus, which is able to retrotranscribe its specific genes both into human and MT genomes.

  4. Adaptive significance of synchronous chorusing in an acoustically signalling wolf spider.

    PubMed Central

    Kotiaho, Janne S.; Alatalo, Rauno V.; Mappes, Johanna; Parri, Silja

    2004-01-01

    Synchronous sexual signalling is a behavioural phenomenon that has received considerable theoretical interest, but surprisingly few empirical tests have been conducted. Here, we present a set of experiments designed to determine (i) whether the sexual signalling of the drumming wolf spider Hygrolycosa rubrofasciata is synchronous, and (ii) whether the synchrony may have evolved through female preference. Using controlled playback experiments, we found that males actively synchronized their drumming bouts with other males and females significantly preferred closely synchronized drumming clusters compared with loose clusters. In loose clusters, the first drumming signals attracted the most female responses, whereas in close clusters, the last drumming signals were the most heeded. We suggest that this female preference for the last drummer can maintain male synchronous signalling in H. rubrofasciata. PMID:15315901

  5. Acoustic emission frequency discrimination

    NASA Technical Reports Server (NTRS)

    Sugg, Frank E. (Inventor); Graham, Lloyd J. (Inventor)

    1988-01-01

    In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.

  6. Acoustic vibration analysis for utilization of woody plant in space environment

    NASA Astrophysics Data System (ADS)

    Chida, Yukari; Yamashita, Masamichi; Hashimoto, Hirofumi; Sato, Seigo; Tomita-Yokotani, Kaori; Baba, Keiichi; Suzuki, Toshisada; Motohashi, Kyohei; Sakurai, Naoki; Nakagawa-izumi, Akiko

    2012-07-01

    We are proposing to raise woody plants for space agriculture in Mars. Space agriculture has the utilization of wood in their ecosystem. Nobody knows the real tree shape grown under space environment under the low or micro gravitational conditions such as outer environment. Angiosperm tree forms tension wood for keeping their shape. Tension wood formation is deeply related to gravity, but the details of the mechanism of its formation has not yet been clarified. For clarifying the mechanism, the space experiment in international space station, ISS is the best way to investigate about them as the first step. It is necessary to establish the easy method for crews who examine the experiments at ISS. Here, we are proposing to investigate the possibility of the acoustic vibration analysis for the experiment at ISS. Two types of Japanese cherry tree, weeping and upright types in Prunus sp., were analyzed by the acoustic vibration method. Coefficient-of-variation (CV) of sound speed was calculated by the acoustic vibration analysis. The amount of lignin and decomposed lignin were estimated by both Klason and Py-GC/MS method, respectively. The relationships of the results of acoustic vibration analysis and the inner components in tested woody materials were investigated. After the experiments, we confirm the correlation about them. Our results indicated that the acoustic vibration analysis would be useful for determining the inside composition as a nondestructive method in outer space environment.

  7. A scattering analysis of echoes due to biosonar signals emitted by foraging beaked whales

    NASA Astrophysics Data System (ADS)

    Jones, Benjamin A.; Stanton, Timothy K.; Lavery, Andone C.; Johnson, Mark P.; Madsen, Peter T.; Tyack, Peter L.

    2005-09-01

    Blainville's beaked whales (Mesoplodon densirostris) hunt their prey by echolocation at depths of more than 500 meters. These whales use a FM upswept, ultrasonic click, of greater than an octave bandwidth to search for, localize, and close on individual prey which generally consist of mesopelagic fishes and squid. It is well known that acoustic scattering from organisms of varying morphology (e.g., swimbladder-bearing or fluidlike) is strongly frequency dependent. However, it is unknown if the broadband nature of the whales' outgoing signal, and the frequency dependence of the echoes, is a key component in the classification and selection of their prey. Non-invasive, acoustic ``Dtags,'' which sample stereo acoustic data at a rate which satisfies the high-frequency Nyquist criterion for the animal's transmit signal, were affixed to beaked whales. The Dtags successfully recorded transmitted signals and associated echoes. Structure was observed in the frequency content of echoes from isolated targets in the water column which may be used for classification by the whales. An analysis of the echoes identified as possibly due to prey has demonstrated that multiple classes of frequency responses are present. These results will be compared with the frequency responses of possible prey types.

  8. A robust H∞ learning approach to blind separation of slowly time-varying mixture of acoustic electromechanical signals

    NASA Astrophysics Data System (ADS)

    Das, Niva; Routray, Aurobinda; Dash, Pradipta Kishor

    2009-08-01

    Although many techniques have been developed for solving the blind source separation (BSS) problem, some issues related to robustness of BSS algorithms are yet to be addressed. Most of the BSS algorithms developed assume the mixing system to be stationary. In this paper, we present a robust approach based on H∞ learning to address the instantaneous BSS problem in a non-stationary mixing environment. The motivation behind applying H∞ filter is that these are robust to errors arising out of model uncertainties, parameter variations and additive noise. Acoustic electromechanical signals have been considered for simulation purpose. Simulation results demonstrate that the H∞ filter performs superior to Kalman filter and VS-NGA algorithm. To ensure practicability of the proposed approach, the H∞ learning algorithm has been implemented and tested on Texas Instrument's TMS320C6713 floating point DSP platform successfully.

  9. Preprocessing and analysis of the ECG signals

    NASA Astrophysics Data System (ADS)

    Zhu, Jianmin; Zhang, Xiaolan; Wang, Zhongyu; Wang, Xiaoling

    2008-10-01

    According to the request of automatic analysis and depressing high frequency interference of the ECG signals, this paper applies low-pass filter to preprocess ECG signals, and proposes a QRS complex detection method based on wavelet transform, which takes advantage of Marr wavelet to decompose and filter the ECG signals with Mallat algorithm, using the relationship between wavelet transform and signal singularity to detect QRS complex with amplitude threshold method in scale 3, and to detect P wave and R wave in scale 4. Meanwhile, compositive detection method is used for re-detection, thus to improving the detection accuracy ratio. At last, records from ECG database of MIT/BIH which is widely accepted in the world are used to test the algorithm. And the result shows that correction detecting ratio under this algorithm has been more than 99.8 percent. The detection method in this paper is simple and running fast, and is easy to be realized in the real-time detecting system using for clinical diagnosis.

  10. Fractal Dimension in Epileptic EEG Signal Analysis

    NASA Astrophysics Data System (ADS)

    Uthayakumar, R.

    Fractal Analysis is the well developed theory in the data analysis of non-linear time series. Especially Fractal Dimension is a powerful mathematical tool for modeling many physical and biological time signals with high complexity and irregularity. Fractal dimension is a suitable tool for analyzing the nonlinear behaviour and state of the many chaotic systems. Particularly in analysis of chaotic time series such as electroencephalograms (EEG), this feature has been used to identify and distinguish specific states of physiological function.Epilepsy is the main fatal neurological disorder in our brain, which is analyzed by the biomedical signal called Electroencephalogram (EEG). The detection of Epileptic seizures in the EEG Signals is an important tool in the diagnosis of epilepsy. So we made an attempt to analyze the EEG in depth for knowing the mystery of human consciousness. EEG has more fluctuations recorded from the human brain due to the spontaneous electrical activity. Hence EEG Signals are represented as Fractal Time Series.The algorithms of fractal dimension methods have weak ability to the estimation of complexity in the irregular graphs. Divider method is widely used to obtain the fractal dimension of curves embedded into a 2-dimensional space. The major problem is choosing initial and final step length of dividers. We propose a new algorithm based on the size measure relationship (SMR) method, quantifying the dimensional behaviour of irregular rectifiable graphs with minimum time complexity. The evidence for the suitability (equality with the nature of dimension) of the algorithm is illustrated graphically.We would like to demonstrate the criterion for the selection of dividers (minimum and maximum value) in the calculation of fractal dimension of the irregular curves with minimum time complexity. For that we design a new method of computing fractal dimension (FD) of biomedical waveforms. Compared to Higuchi's algorithm, advantages of this method include

  11. Acoustic effects analysis utilizing speckle pattern with fixed-particle Monte Carlo

    NASA Astrophysics Data System (ADS)

    Vakili, Ali; Hollmann, Joseph A.; Holt, R. Glynn; DiMarzio, Charles A.

    2016-03-01

    Optical imaging in a turbid medium is limited because of multiple scattering a photon undergoes while traveling through the medium. Therefore, optical imaging is unable to provide high resolution information deep in the medium. In the case of soft tissue, acoustic waves unlike light, can travel through the medium with negligible scattering. However, acoustic waves cannot provide medically relevant contrast as good as light. Hybrid solutions have been applied to use the benefits of both imaging methods. A focused acoustic wave generates a force inside an acoustically absorbing medium known as acoustic radiation force (ARF). ARF induces particle displacement within the medium. The amount of displacement is a function of mechanical properties of the medium and the applied force. To monitor the displacement induced by the ARF, speckle pattern analysis can be used. The speckle pattern is the result of interfering optical waves with different phases. As light travels through the medium, it undergoes several scattering events. Hence, it generates different scattering paths which depends on the location of the particles. Light waves that travel along these paths have different phases (different optical path lengths). ARF induces displacement to scatterers within the acoustic focal volume, and changes the optical path length. In addition, temperature rise due to conversion of absorbed acoustic energy to heat, changes the index of refraction and therefore, changes the optical path length of the scattering paths. The result is a change in the speckle pattern. Results suggest that the average change in the speckle pattern measures the displacement of particles and temperature rise within the acoustic wave focal area, hence can provide mechanical and thermal properties of the medium.

  12. West Texas array experiment: Noise and source characterization of short-range infrasound and acoustic signals, along with lab and field evaluation of Intermountain Laboratories infrasound microphones

    NASA Astrophysics Data System (ADS)

    Fisher, Aileen

    The term infrasound describes atmospheric sound waves with frequencies below 20 Hz, while acoustics are classified within the audible range of 20 Hz to 20 kHz. Infrasound and acoustic monitoring in the scientific community is hampered by low signal-to-noise ratios and a limited number of studies on regional and short-range noise and source characterization. The JASON Report (2005) suggests the infrasound community focus on more broad-frequency, observational studies within a tactical distance of 10 km. In keeping with that recommendation, this paper presents a study of regional and short-range atmospheric acoustic and infrasonic noise characterization, at a desert site in West Texas, covering a broad frequency range of 0.2 to 100 Hz. To spatially sample the band, a large number of infrasound gauges was needed. A laboratory instrument analysis is presented of the set of low-cost infrasound sensors used in this study, manufactured by Inter-Mountain Laboratories (IML). Analysis includes spectra, transfer functions and coherences to assess the stability and range of the gauges, and complements additional instrument testing by Sandia National Laboratories. The IMLs documented here have been found reliably coherent from 0.1 to 7 Hz without instrument correction. Corrections were built using corresponding time series from the commercially available and more expensive Chaparral infrasound gauge, so that the corrected IML outputs were able to closely mimic the Chaparral output. Arrays of gauges are needed for atmospheric sound signal processing. Our West Texas experiment consisted of a 1.5 km aperture, 23-gauge infrasound/acoustic array of IMLs, with a compact, 12 m diameter grid-array of rented IMLs at the center. To optimize signal recording, signal-to-noise ratio needs to be quantified with respect to both frequency band and coherence length. The higher-frequency grid array consisted of 25 microphones arranged in a five by five pattern with 3 meter spacing, without

  13. Method and apparatus for background signal reduction in opto-acoustic absorption measurement

    NASA Technical Reports Server (NTRS)

    Rosengren, L. G. (Inventor)

    1976-01-01

    The sensitivity of an opto-acoustic absorption detector is increased to make it possible to measure trace amounts of constituent gases. A second beam radiation path is created through the sample cell identical to a first path except as to length, alternating the beam through the two paths and minimizing the detected pressure difference for the two paths while the beam wavelength is tuned away from the absorption lines of the sample. Then with the beam wavelength tuned to the absorption line of any constituent of interest, the pressure difference is a measure of trace amounts of the constituent. The same improved detector may also be used for measuring the absorption coefficient of known concentrations of absorbing gases.

  14. Acoustic underwater signals with a probable function during competitive feeding in a tadpole

    NASA Astrophysics Data System (ADS)

    Reeve, Erik; Ndriantsoa, Serge Herilala; Strauß, Axel; Randrianiaina, Roger-Daniel; Rasolonjatovo Hiobiarilanto, Tahiry; Glaw, Frank; Glos, Julian; Vences, Miguel

    2011-02-01

    Acoustic communication is widespread among adult stages of terrestrial animals and fish and has also been observed in insect larvae. We report underwater acoustic communication in the larvae of a frog, Gephyromantis azzurrae, from Isalo, a sandstone massif in western Madagascar. According to our field data, these tadpoles live in streams and prefer habitats characterized by comparatively low temperatures, shallow water depth, and a relatively fast current. Feeding experiments indicated that the tadpoles are carnivorous and macrophagous. They consumed insect larvae and, to a lesser extent, small shrimps, and conspecific as well as heterospecific tadpoles. Calls of these tadpoles consisted either of single click notes or of irregular series of various clicks. Some complex calls have a pulsed structure with three to nine indistinct energy pulses. Production of the pulses coincided with rapid closure of the jaw sheaths and often with an upward movement of the body. Calls were emitted while attacking prey and occurred significantly more often when attacking conspecifics. Tadpoles that had not been fed for some time emitted sounds more frequently than those that had been regularly fed. The spectral frequency of the calls differed in tadpole groups of different size and was higher in groups of smaller tadpoles, suggesting that spectral frequency carries some information about tadpole size which might be important during competitive feeding to assess size and strength of competitors. This report differs from those for the larvae of South American horned frogs, Ceratophrys ornata. These are the only other tadpoles for which sound production has reliably been reported but the calls of Ceratophrys tadpoles occur mainly in a defensive context.

  15. Beamforming in an acoustic shadow

    NASA Technical Reports Server (NTRS)

    Havelock, David; Stinson, Michael; Daigle, Gilles

    1993-01-01

    The sound field deep within an acoustic shadow region is less well understood than that outside the shadow region. Signal levels are substantially lower within the shadow, but beamforming difficulties arise for other reasons such as loss of spatial coherence. Based on analysis of JAPE-91 data, and other data, three types of characteristic signals within acoustic shadow regions are identified. These signal types may correspond to different, intermittent signal propagation conditions. Detection and classification algorithms might take advantage of the signal characteristics. Frequency coherence is also discussed. The extent of coherence across frequencies is shown to be limited, causing difficulties for source classification based on harmonic amplitude relationships. Discussions emphasize short-term characteristics on the order of one second. A video presentation on frequency coherence shows the similarity, in the presence of atmospheric turbulence, between the received signal from a stable set of harmonics generated by a loudspeaker and that received from a helicopter hovering behind a hill.

  16. Acoustic emission analysis: A test method for metal joints bonded by adhesives

    NASA Technical Reports Server (NTRS)

    Brockmann, W.; Fischer, T.

    1978-01-01

    Acoustic emission analysis is applied to study adhesive joints which had been subjected to mechanical and climatic stresses, taking into account conditions which make results applicable to adhesive joints used in aerospace technology. Specimens consisting of the alloy AlMgSi0.5 were used together with a phenolic resin adhesive, an epoxy resin modified with a polyamide, and an epoxy resin modified with a nitrile. Results show that the acoustic emission analysis provides valuable information concerning the behavior of adhesive joints under load and climatic stresses.

  17. Helicopter blade-vortex interaction locations: Scale-model acoustics and free-wake analysis results

    NASA Technical Reports Server (NTRS)

    Hoad, Danny R.

    1987-01-01

    The results of a model rotor acoustic test in the Langley 4by 7-Meter Tunnel are used to evaluate a free-wake analytical technique. An acoustic triangulation technique is used to locate the position in the rotor disk where the blade-vortex interaction noise originates. These locations, along with results of the rotor free-wake analysis, are used to define the geometry of the blade-vortex interaction noise phenomena as well as to determine if the free-wake analysis is a capable diagnostic tool. Data from tests of two teetering rotor systems are used in these analyses.

  18. Frequency and time pattern differences in acoustic signals produced by Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae)in stored maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The acoustic signals emitted by the last stage larval instars and adults of Prostephanus truncatus and Sitophilus zeamais in stored maize were investigated. Analyses were performed to identify brief, 1-10-ms broadband sound impulses of five different frequency patterns produced by larvae and adults,...

  19. Thermal Acoustic Oscillation: Causes, Detection, Analysis, and Prevention

    NASA Technical Reports Server (NTRS)

    Christie, R. J.; Hartwig, J. W.

    2014-01-01

    Thermal Acoustic Oscillations (TAO) can occur in cryogenic systems and produce significant sources of heat. This source of heat can increase the boil off rate of cryogenic propellants in spacecraft storage tanks and reduce mission life. This paper discusses the causes of TAO, how it can be detected, what analyses can be done to predict it, and how to prevent it from occurring.The paper provides practical insight into what can aggravate instability, practical methods for mitigation, and when TAO does not occur. A real life example of a cryogenic system with an unexpected heat source is discussed, along with how TAO was confirmed and eliminated.

  20. Field support, data analysis and associated research for the acoustic grenade sounding program

    NASA Technical Reports Server (NTRS)

    Barnes, T. G.; Bullard, E. R.

    1976-01-01

    Temperature and horizontal winds in the 30 to 90 km altitude range of the upper atmosphere, were determined by acoustic grenade soundings conducted at Wallops Island, Virginia and Kourou, French Guiana. Field support provided at these locations included deployment of the large area microphone system, supervision, maintenance and operation of sound ranging stations; and coordination of activities. Data analysis efforts included the analysis of field data to determine upper atmospheric meteorological parameters. Profiles for upper atmospheric temperature, wind and density are provided in plots and tables for each of the acoustic grenade soundings conducted during the contract period. Research efforts were directed toward a systematic comparison of temperature data from acoustic grenade with other meteorological sensor probes in the upper atmosphere.

  1. Computer analysis of foetal monitoring signals.

    PubMed

    Nunes, Inês; Ayres-de-Campos, Diogo

    2016-01-01

    Five systems for computer analysis of foetal monitoring signals are currently available, incorporating the evaluation of cardiotocographic (CTG) or combined CTG with electrocardiographic ST data. All systems have been integrated with central monitoring stations, allowing the simultaneous monitoring of several tracings on the same computer screen in multiple hospital locations. Computer analysis elicits real-time visual and sound alerts for health care professionals when abnormal patterns are detected, with the aim of prompting a re-evaluation and subsequent clinical action, if considered necessary. Comparison between the CTG analyses provided by the computer and clinical experts has been carried out in all systems, and in three of them, the accuracy of computer alerts in predicting newborn outcomes was evaluated. Comparisons between these studies are hampered by the differences in selection criteria and outcomes. Two of these systems have just completed multicentre randomised clinical trials comparing them with conventional CTG monitoring, and their results are awaited shortly. For the time being, there is limited evidence regarding the impact of computer analysis of foetal monitoring signals on perinatal indicators and on health care professionals' behaviour. PMID:26211832

  2. Transducer Signal Noise Analysis for Sensor Authentication

    SciTech Connect

    John M. Svoboda; Mark J. Schanfein

    2012-07-01

    The abstract is being passed through STIMS for submision to the conference. International safeguards organizations charged with promoting the peaceful use of nuclear energy employ unattended and remote monitoring systems supplemented with onsite inspections to ensure nuclear materials are not diverted for weaponization purposes. These systems are left unattended for periods of several months between inspections. During these periods physical security means are the main deterrent used to detect intentional monitoring system tampering. The information gathering components are locked in secure and sealed rooms. The sensor components (i.e. neutron and gamma detectors) are located throughout the plant in unsecure areas where sensor tampering could take place during the periods between inspections. Sensor tampering could allow the diversion of nuclear materials from the accepted and intended use to uses not consistent with the peaceful use of nuclear energy. A method and an apparatus is presented that address the detection of sensor tampering during the periods between inspections. It was developed at the Idaho National Laboratory (INL) for the Department of Energy (DOE) in support of the IAEA. The method is based on the detailed analysis of the sensor noise floor after the sensor signal is removed. The apparatus consists of a 2.1” x 2.6” electronic circuit board containing all signal conditioning and processing components and a laptop computer running an application that acquires and stores the analysis results between inspection periods. The sensors do not require any modification and are remotely located in their normal high radiation zones. The apparatus interfaces with the sensor signal conductors using a simple pass through connector at the normal sensor electronics interface package located in the already secure and sealed rooms. The apparatus does not require hardening against the effects of radiation due to its location. Presented is the apparatus design

  3. Elaborate visual and acoustic signals evolve independently in a large, phenotypically diverse radiation of songbirds.

    PubMed

    Mason, Nicholas A; Shultz, Allison J; Burns, Kevin J

    2014-08-01

    The concept of a macroevolutionary trade-off among sexual signals has a storied history in evolutionary biology. Theory predicts that if multiple sexual signals are costly for males to produce or maintain and females prefer a single, sexually selected trait, then an inverse correlation between sexual signal elaborations is expected among species. However, empirical evidence for what has been termed the 'transfer hypothesis' is mixed, which may reflect different selective pressures among lineages, evolutionary covariates or methodological differences among studies. Here, we examine interspecific correlations between song and plumage elaboration in a phenotypically diverse, widespread radiation of songbirds, the tanagers. The tanagers (Thraupidae) are the largest family of songbirds, representing nearly 10% of all songbirds. We assess variation in song and plumage elaboration across 301 species, representing the largest scale comparative study of multimodal sexual signalling to date. We consider whether evolutionary covariates, including habitat, structural and carotenoid-based coloration, and subfamily groupings influence the relationship between song and plumage elaboration. We find that song and plumage elaboration are uncorrelated when considering all tanagers, although the relationship between song and plumage complexity varies among subfamilies. Taken together, we find that elaborate visual and vocal sexual signals evolve independently among tanagers. PMID:24943371

  4. Elaborate visual and acoustic signals evolve independently in a large, phenotypically diverse radiation of songbirds

    PubMed Central

    Mason, Nicholas A.; Shultz, Allison J.; Burns, Kevin J.

    2014-01-01

    The concept of a macroevolutionary trade-off among sexual signals has a storied history in evolutionary biology. Theory predicts that if multiple sexual signals are costly for males to produce or maintain and females prefer a single, sexually selected trait, then an inverse correlation between sexual signal elaborations is expected among species. However, empirical evidence for what has been termed the ‘transfer hypothesis’ is mixed, which may reflect different selective pressures among lineages, evolutionary covariates or methodological differences among studies. Here, we examine interspecific correlations between song and plumage elaboration in a phenotypically diverse, widespread radiation of songbirds, the tanagers. The tanagers (Thraupidae) are the largest family of songbirds, representing nearly 10% of all songbirds. We assess variation in song and plumage elaboration across 301 species, representing the largest scale comparative study of multimodal sexual signalling to date. We consider whether evolutionary covariates, including habitat, structural and carotenoid-based coloration, and subfamily groupings influence the relationship between song and plumage elaboration. We find that song and plumage elaboration are uncorrelated when considering all tanagers, although the relationship between song and plumage complexity varies among subfamilies. Taken together, we find that elaborate visual and vocal sexual signals evolve independently among tanagers. PMID:24943371

  5. The two parts of the blackcap song: Acoustic analysis and male responses to playbacks.

    PubMed

    Linossier, Juliette; Courvoisier, Hélène; Aubin, Thierry

    2015-12-01

    Bird songs are complex manifold acoustic signals serving two main functions: mate attraction and territorial defense. The way information is encoded in the song often reflects adaptation to proximate and ultimate constraints. Male blackcaps, Sylvia atricapilla, display versatile songs with two parts, a warble and a whistle, whose functions remain unclear. We showed that the two parts of songs differ in terms of intensity, frequency and temporal parameters. They also contain totally different sets of syllables. Furthermore, the warble is versatile whereas the whistle part shows syllable sharing between individuals leaving closeby. Altogether, the results of our analysis suggest that the two parts encode different information potentially directed to different audiences. In order to test the potential function of these two parts, we performed playback experiments by broadcasting entire songs and each part separately. Warble and whistle alone are sufficient to trigger male responses and males sing both parts in responses to all stimuli, showing that both parts of the song are used in male-male competition. It is suggested that the segregation of information in the blackcap song could be related to public versus private communication, used in both intra- and intersexual contexts, rather than directed to male versus female audiences only. PMID:26522931

  6. Acoustical analysis of Spanish vowels produced by laryngectomized subjects.

    PubMed

    Cervera, T; Miralles, J L; González-Alvarez, J

    2001-10-01

    The purpose of this study was to describe the acoustic characteristics of Spanish vowels in subjects who had undergone a total laryngectomy and to compare the results with those obtained in a control group of subjects who spoke normally. Our results are discussed in relation to those obtained in previous studies with English-speaking laryngectomized patients. The comparison between English and Spanish, which diFfer widely in the size of their vowel inventories, will help us to determine specific or universal vowel production characteristics in these patients. Our second objective was to relate the acoustic properties of these vowels to the perceptual data obtained in our previous work (J. L. Miralles & T. Cervera, 1995). In that study, results indicated that vowels produced by alaryngeal speakers were well perceived in word context. Vowels were produced in CVCV word context by two groups of patients who had undergone laryngectomy: tracheoesophageal speakers (TES) and esophageal speakers. In addition a control group of normal talkers was included. Audio recordings of 24 Spanish words produced by each speaker were analyzed using CSL (Kay Elemetrics). Results showed that F1, F2, and vowel duration of alaryngeal speakers differ significantly from normal values. In general, laryngectomized patients produce vowels with higher formant frequencies and longer durations than the group of laryngeal subjects. Thus, the data indicate modifications either in the frequency or temporal domain, following the same tendency found in previous studies with English-speaking laryngectomized speakers. PMID:11708538

  7. An intelligent sensor array distributed system for vibration analysis and acoustic noise characterization of a linear switched reluctance actuator.

    PubMed

    Salvado, José; Espírito-Santo, António; Calado, Maria

    2012-01-01

    This paper proposes a distributed system for analysis and monitoring (DSAM) of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs). The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications. PMID:22969364

  8. An Intelligent Sensor Array Distributed System for Vibration Analysis and Acoustic Noise Characterization of a Linear Switched Reluctance Actuator

    PubMed Central

    Salvado, José; Espírito-Santo, António; Calado, Maria

    2012-01-01

    This paper proposes a distributed system for analysis and monitoring (DSAM) of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs). The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications. PMID:22969364

  9. Effect of sound on gap-junction-based intercellular signaling: Calcium waves under acoustic irradiation

    NASA Astrophysics Data System (ADS)

    Deymier, P. A.; Swinteck, N.; Runge, K.; Deymier-Black, A.; Hoying, J. B.

    2015-11-01

    We present a previously unrecognized effect of sound waves on gap-junction-based intercellular signaling such as in biological tissues composed of endothelial cells. We suggest that sound irradiation may, through temporal and spatial modulation of cell-to-cell conductance, create intercellular calcium waves with unidirectional signal propagation associated with nonconventional topologies. Nonreciprocity in calcium wave propagation induced by sound wave irradiation is demonstrated in the case of a linear and a nonlinear reaction-diffusion model. This demonstration should be applicable to other types of gap-junction-based intercellular signals, and it is thought that it should be of help in interpreting a broad range of biological phenomena associated with the beneficial therapeutic effects of sound irradiation and possibly the harmful effects of sound waves on health.

  10. Performance Analysis for Acoustic Echo Cancellation Systems based on Variable Step Size NLMS algorithms

    NASA Astrophysics Data System (ADS)

    Hegde, Rajeshwari; Balachandra, K.; Rao, Madhusudhan

    2011-12-01

    Acoustic echo cancellation is an essential signal enhancement tool in hands-free communication. Loudspeaker signals are picked up by a microphone and are fed back to the correspondent, resulting in an undesired echo. Nowadays, adaptive filtering techniques are typically employed to suppress this echo. In acoustic applications long filters need to be adapted for sufficient echo suppression. Classical adaptation schemes such as LMS are quite expensive for accurate echo path modeling in highly reverberating environments. In order to cope with dynamic signals, step-size μ is often normalized by taking it inversely proportional to the energy of x. This normalized version of LMS (NLMS) is typically used in practice. This paper discusses various variable step-size NLMS based algorithms which can be implemented in acoustic echo cancelling applications. The performance of these algorithms in terms of ERLE and NSEC curves are obtained and comparison between them is done. Also a simple and novel Double-Talk Detection scheme is proposed in this paper.

  11. Perception of Male Caller Identity in Koalas (Phascolarctos cinereus): Acoustic Analysis and Playback Experiments

    PubMed Central

    Charlton, Benjamin D.; Ellis, William A. H.; McKinnon, Allan J.; Brumm, Jacqui; Nilsson, Karen; Fitch, W. Tecumseh

    2011-01-01

    The ability to signal individual identity using vocal signals and distinguish between conspecifics based on vocal cues is important in several mammal species. Furthermore, it can be important for receivers to differentiate between callers in reproductive contexts. In this study, we used acoustic analyses to determine whether male koala bellows are individually distinctive and to investigate the relative importance of different acoustic features for coding individuality. We then used a habituation-discrimination paradigm to investigate whether koalas discriminate between the bellow vocalisations of different male callers. Our results show that male koala bellows are highly individualized, and indicate that cues related to vocal tract filtering contribute the most to vocal identity. In addition, we found that male and female koalas habituated to the bellows of a specific male showed a significant dishabituation when they were presented with bellows from a novel male. The significant reduction in behavioural response to a final rehabituation playback shows this was not a chance rebound in response levels. Our findings indicate that male koala bellows are highly individually distinctive and that the identity of male callers is functionally relevant to male and female koalas during the breeding season. We go on to discuss the biological relevance of signalling identity in this species' sexual communication and the potential practical implications of our findings for acoustic monitoring of male population levels. PMID:21633499

  12. Assessment of Infant Cry: Acoustic Cry Analysis and Parental Perception

    ERIC Educational Resources Information Center

    LaGasse, Linda L.; Neal, A. Rebecca; Lester, Barry M.

    2005-01-01

    Infant crying signals distress to potential caretakers who can alleviate the aversive conditions that gave rise to the cry. The cry signal results from coordination among several brain regions that control respiration and vocal cord vibration from which the cry sounds are produced. Previous work has shown a relationship between acoustic…

  13. Mountain chickadees from different elevations sing different songs: acoustic adaptation, temporal drift or signal of local adaptation?

    PubMed

    Branch, Carrie L; Pravosudov, Vladimir V

    2015-04-01

    Song in songbirds is widely thought to function in mate choice and male-male competition. Song is also phenotypically plastic and typically learned from local adults; therefore, it varies across geographical space and can serve as a cue for an individual's location of origin, with females commonly preferring males from their respective location. Geographical variation in song dialect may reflect acoustic adaptation to different environments and/or serve as a signal of local adaptation. In montane environments, environmental differences can occur over an elevation gradient, favouring local adaptations across small spatial scales. We tested whether food caching mountain chickadees, known to exhibit elevation-related differences in food caching intensity, spatial memory and the hippocampus, also sing different dialects despite continuous distribution and close proximity. Male songs were collected from high and low elevations at two different mountains (separated by 35 km) to test whether song differs between elevations and/or between adjacent populations at each mountain. Song structure varied significantly between high and low elevation adjacent populations from the same mountain and between populations from different mountains at the same elevations, despite a continuous distribution across each mountain slope. These results suggest that elevation-related differences in song structure in chickadees might serve as a signal for local adaptation. PMID:26064641

  14. Mountain chickadees from different elevations sing different songs: acoustic adaptation, temporal drift or signal of local adaptation?

    PubMed Central

    Branch, Carrie L.; Pravosudov, Vladimir V.

    2015-01-01

    Song in songbirds is widely thought to function in mate choice and male–male competition. Song is also phenotypically plastic and typically learned from local adults; therefore, it varies across geographical space and can serve as a cue for an individual's location of origin, with females commonly preferring males from their respective location. Geographical variation in song dialect may reflect acoustic adaptation to different environments and/or serve as a signal of local adaptation. In montane environments, environmental differences can occur over an elevation gradient, favouring local adaptations across small spatial scales. We tested whether food caching mountain chickadees, known to exhibit elevation-related differences in food caching intensity, spatial memory and the hippocampus, also sing different dialects despite continuous distribution and close proximity. Male songs were collected from high and low elevations at two different mountains (separated by 35 km) to test whether song differs between elevations and/or between adjacent populations at each mountain. Song structure varied significantly between high and low elevation adjacent populations from the same mountain and between populations from different mountains at the same elevations, despite a continuous distribution across each mountain slope. These results suggest that elevation-related differences in song structure in chickadees might serve as a signal for local adaptation. PMID:26064641

  15. Effects of signal attenuation in natural media on interpretation of acoustic emissions in the context early warning systems

    NASA Astrophysics Data System (ADS)

    Faillettaz, Jerome; Or, Dani

    2015-04-01

    Gravity driven instabilities in natural media such as rockfalls, landslides, snow avalanches or glacier break-offs represent a significant class of natural hazards. Reliable prediction of imminence of such events combined with timely evacuation remain a challenge because material failure is a non linear process involving inherent heterogeneities affecting the outcome. Nevertheless, such materials break gradually with the weakest parts breaking first, producing precursory "micro-cracks" and associated elastic waves traveling in the material. The monitoring of such acoustic/micro-seismic activity offers valuable information on the progression of damage and imminence of global failure. The main challenge is that acoustic waves are strongly attenuated during their travel through natural media thereby introducing ambiguity in the interpretation of the magnitude (severity) or leading to loss of detection for faraway events. For example, a micro-crack event would be measured as a large event if occurring close to the sensor, and as a small event if far from the sensor ( or may not be detected at all). A more complete picture of acoustic emissions or micro- seismic activity requires deployment of a dense network of sensors that enables localization of sources and thus the determination of initial energy released with each event. However, such networks are prohibitively costly difficult to analyze in real time over scales of interest. Is it possible to find a way to analyze directly in real time the measured micro-seismic activity to infer the slope mechanical status? Following a qualitative description of the observation problem and the processes leading to attenuation, a quantitative analysis is performed using a numerical model based on the classical Fiber Bundle Model. Introducing a basic attenuation law in such simple models enables to directly compare un-attenuated and attenuated acoustic activity (and also avalanche size-frequency distribution) at any location

  16. A High Performance Pocket-Size System for Evaluations in Acoustic Signal Processing

    NASA Astrophysics Data System (ADS)

    Rass, Uwe; Steeger, Gerhard H.

    2001-12-01

    Custom-made hardware is attractive for sophisticated signal processing in wearable electroacoustic devices, but has a high initial cost overhead. Thus, signal processing algorithms should be tested thoroughly in real application environments by potential end users prior to the hardware implementation. In addition, the algorithms should be easily alterable during this test phase. A wearable system which meets these requirements has been developed and built. The system is based on the high performance signal processor Motorola DSP56309. This device also includes high quality stereo analog-to-digital-(ADC)- and digital-to-analog-(DAC)-converters with 20 bit word length each. The available dynamic range exceeds 88 dB. The input and output gains can be adjusted by digitally controlled potentiometers. The housing of the unit is small enough to carry it in a pocket (dimensions 150 × 80 × 25 mm). Software tools have been developed to ease the development of new algorithms. A set of configurable Assembler code modules implements all hardware dependent software routines and gives easy access to the peripherals and interfaces. A comfortable fitting interface allows easy control of the signal processing unit from a PC, even by assistant personnel. The device has proven to be a helpful means for development and field evaluations of advanced new hearing aid algorithms, within interdisciplinary research projects. Now it is offered to the scientific community.

  17. The detection of cavitation in hydraulic machines by use of ultrasonic signal analysis

    NASA Astrophysics Data System (ADS)

    Gruber, P.; Odermatt, P.; Etterlin, M.; Lerch, T.; Frei, M.; Farhat, M.

    2014-03-01

    This presentation describes an experimental approach for the detection of cavitation in hydraulic machines by use of ultrasonic signal analysis. Instead of using the high frequency pulses (typically 1MHz) only for transit time measurement different other signal characteristics are extracted from the individual signals and its correlation function with reference signals in order to gain knowledge of the water conditions. As the pulse repetition rate is high (typically 100Hz), statistical parameters can be extracted of the signals. The idea is to find patterns in the parameters by a classifier that can distinguish between the different water states. This classification scheme has been applied to different cavitation sections: a sphere in a water flow in circular tube at the HSLU in Lucerne, a NACA profile in a cavitation tunnel and a Francis model test turbine both at LMH in Lausanne. From the signal raw data several statistical parameters in the time and frequency domain as well as from the correlation function with reference signals have been determined. As classifiers two methods were used: neural feed forward networks and decision trees. For both classification methods realizations with lowest complexity as possible are of special interest. It is shown that three signal characteristics, two from the signal itself and one from the correlation function are in many cases sufficient for the detection capability. The final goal is to combine these results with operating point, vibration, acoustic emission and dynamic pressure information such that a distinction between dangerous and not dangerous cavitation is possible.

  18. The vocal repertoire of adult male blue monkeys (Cercopithecus mitis stulmanni): a quantitative analysis of acoustic structure.

    PubMed

    Fuller, James Lewis

    2014-03-01

    Vocal signals are key elements in understanding species' behavior, sociality, and evolution. Quantified repertoires serve as foundations for investigating usage and function of particular signals, and also provide a basis for comparative analyses among individuals, populations, and taxa to explore how entire signal systems evolve. This study presents a descriptive catalogue of all vocal signals used by adult male blue monkeys (Cercopithecus mitis stuhlmanni). During 12 months in the Kakamega Forest, Kenya, I observed and digitally recorded vocal behavior of 32 adult males across a variety of socioecological contexts. From recordings, I measured 18 temporal-frequency parameters. Undirected ordination and hierarchical cluster analysis identified six distinct call types regularly used by males: ant, boom, ka, katrain, nasal scream, and pyow. Cross-validated discriminant function analysis supported the classifications. The repertoire is best described as discrete, though some gradation occurs between pyows and ants. Summary of acoustic structure and exemplar spectrograms are provided for each call type, along with preliminary examination of socioecological contexts in which they were produced. Discussion addresses repertoire structure, similarity to other taxa, and potential for functional inferences. PMID:24130044

  19. Analysis of Fumarole Acoustics at Aso Volcano, Japan

    NASA Astrophysics Data System (ADS)

    McKee, K. F.; Yokoo, A.; Fee, D.; Huang, Y. C.; Yoshikawa, S.; Utsugi, M.; Minami, T.; Ohkura, T.

    2015-12-01

    The lowermost portion of large eruption columns is the momentum-driven, fluid flow portion known as a volcanic jet. The perturbation of the atmosphere from this region produces a sound known as jetting or jet noise. Recent work has shown that this volcanic jet noise produced by a volcano has similar characteristics as the sound from jet and rocket engines. The study of volcanic jet noise has gained much from laboratory jet engine studies; however, jet engines have been engineered to reduce noise thereby limiting their use as a comparison tool to the complex, ever-changing volcanic jet. Previous studies have noted that fumaroles produce jet noise without further detailed investigation. The goal of this work is to enhance our understanding of large-scale volcanic jets by studying an accessible, less hazardous fumarolic jet. We aim to characterize the acoustic signature of fumaroles and evaluate if fumarolic jets scale to that of large volcanic jets. To investigate this, we deployed a 6-element acoustic array at two different locations along the edge of the crater wall at Aso Volcano, Japan from early July through mid-August 2015. Approximately two months before this deployment, the pyroclastic cone within Aso's crater partially collapsed into the vent. The cone was constructed during both ash venting and strombolian-style explosive activity in the last year. After the deployment, on July 13 a new small vent opened on the southwest flank of the pyroclastic cone. The vent is several meters in diameter and has consistent gas jetting which produces audible jet noise. To better capture the acoustic signature of the gas jetting we moved the array to the southwestern edge of the crater. The array is 230 meters from the vent and is positioned 54 degrees from the vertical jet axis, a recording angle usually not feasible in volcanic environments. Preliminary investigations suggest directionality at the source and the influence of topography along the propagation path as

  20. Acoustic velocity meter systems

    USGS Publications Warehouse

    Laenen, Antonius

    1985-01-01

    Acoustic velocity meter (AVM) systems operate on the principles that the point-to-point upstream traveltime of an acoustic pulse is longer than the downstream traveltime and that this difference in traveltime can be accurately measured by electronic devices. An AVM system is capable of recording water velocity (and discharge) under a wide range of conditions, but some constraints apply: 1. Accuracy is reduced and performance is degraded if the acoustic path is not a continuous straight line. The path can be bent by reflection if it is too close to a stream boundary or by refraction if it passes through density gradients resulting from variations in either water temperature or salinity. For paths of less than 100 m, a temperature gradient of 0.1' per meter causes signal bending less than 0.6 meter at midchannel, and satisfactory velocity results can be obtained. Reflection from stream boundaries can cause signal cancellation if boundaries are too close to signal path. 2. Signal strength is attenuated by particles or bubbles that absorb, spread, or scatter sound. The concentration of particles or bubbles that can be tolerated is a function of the path length and frequency of the acoustic signal. 3. Changes in streamline orientation can affect system accuracy if the variability is random. 4. Errors relating to signal resolution are much larger for a single threshold detection scheme than for multiple threshold schemes. This report provides methods for computing the effect of various conditions on the accuracy of a record obtained from an AVM. The equipment must be adapted to the site. Field reconnaissance and preinstallation analysis to detect possible problems are critical for proper installation and operation of an AVM system.

  1. FY-93 noncontacting acoustic ultrasonic signature analysis development

    SciTech Connect

    Tow, D.M.; Rodriguez, J.G.; Williamson, R.L.; Blackwood, L.G.

    1994-04-01

    A noncontacting, long-standoff inspection system with proven capabilities in container fill identification has been under development at the Idaho National Engineering Laboratory. The system detects subtle change in container vibration characteristics caused by differences in the physical properties of the fill materials. A container is inspected by acoustically inducting it to vibrate and sensing the vibrational response with a laser vibrometer. A standoff distance of several meters is feasible. In previous work the system proved to be a reliable means of distinguishing between munitions with a variety of chemical fills. During FY-93, the system was modified to improve performance and simplify operation. Other FY-93 accomplishments include progress in modeling the vibrational characteristics of containers and refinements to the statistical classification algorithms. Progress was also made in identifying other applications for this technology.

  2. Atmospheric pressure laser-induced acoustic desorption chemical ionization mass spectrometry for analysis of saturated hydrocarbons.

    PubMed

    Nyadong, Leonard; Quinn, John P; Hsu, Chang S; Hendrickson, Christopher L; Rodgers, Ryan P; Marshall, Alan G

    2012-08-21

    We present atmospheric pressure laser-induced acoustic desorption chemical ionization (AP/LIAD-CI) with O(2) carrier/reagent gas as a powerful new approach for the analysis of saturated hydrocarbon mixtures. Nonthermal sample vaporization with subsequent chemical ionization generates abundant ion signals for straight-chain, branched, and cycloalkanes with minimal or no fragmentation. [M - H](+) is the dominant species for straight-chain and branched alkanes. For cycloalkanes, M(+•) species dominate the mass spectrum at lower capillary temperature (<100 °C) and [M - H](+) at higher temperature (>200 °C). The mass spectrum for a straight-chain alkane mixture (C(21)-C(40)) shows comparable ionization efficiency for all components. AP/LIAD-CI produces molecular weight distributions similar to those for gel permeation chromatography for polyethylene polymers, Polywax 500 and Polywax 655. Coupling of the technique to Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for the analysis of complex hydrocarbon mixtures provides unparalleled mass resolution and accuracy to facilitate unambiguous elemental composition assignments, e.g., 1754 peaks (rms error = 175 ppb) corresponding to a paraffin series (C(12)-C(49), double-bond equivalents, DBE = 0) and higher DBE series corresponding to cycloparaffins containing one to eight rings. Isoabundance-contoured plots of DBE versus carbon number highlight steranes (DBE = 4) of carbon number C(27)-C(30) and hopanes of C(29)-C(35) (DBE = 5), with sterane-to-hopane ratio in good agreement with field ionization (FI) mass spectrometry analysis, but performed at atmospheric pressure. The overall speciation of nonpolar, aliphatic hydrocarbon base oil species offers a promising diagnostic probe to characterize crude oil and its products. PMID:22881221

  3. Quantitative and Descriptive Comparison of Four Acoustic Analysis Systems: Vowel Measurements

    ERIC Educational Resources Information Center

    Burris, Carlyn; Vorperian, Houri K.; Fourakis, Marios; Kent, Ray D.; Bolt, Daniel M.

    2014-01-01

    Purpose: This study examines accuracy and comparability of 4 trademarked acoustic analysis software packages (AASPs): Praat, WaveSurfer, TF32, and CSL by using synthesized and natural vowels. Features of AASPs are also described. Method: Synthesized and natural vowels were analyzed using each of the AASP's default settings to secure 9…

  4. Automated pattern analysis: A newsilent partner in insect acoustic detection studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This seminar reviews methods that have been developed for automated analysis of field-collected sounds used to estimate pest populations and guide insect pest management decisions. Several examples are presented of successful usage of acoustic technology to map insect distributions in field environ...

  5. Acoustic analysis reveals a new cryptic bush–cricket in the Carpathian Mountains (Orthoptera, Phaneropteridae)

    PubMed Central

    Iorgu, Ionuţ Ştefan

    2012-01-01

    Abstract A new morphologically cryptic species of phaneropterid bush–cricket from the genus Isophya is described from the Eastern Carpathian Mountains: Isophya dochia sp. n. Sound analysis and morphological details are discussed in the paper comparing the new species with several Isophya species having similar morphology and acoustic behavior. PMID:23378813

  6. [Acoustic analysis of voice production. Production trial from a clinical perspective].

    PubMed

    Dejonckere, P H

    1986-01-01

    This article presents an overview of relevant methods for acoustic analysis of voice from a clinical point of view: Mean speaking frequency and fundamental frequency in singing; frequency range of phonation; pitch perturbations; intensity range of phonation and phonetogram; cycle-to-cycle amplitude variations; Sound spectrography (Visible Speech) and Long-Time-Average-Spectrum. PMID:3751531

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

    PubMed

    Kral, Zachary; Horn, Walter; Steck, James

    2013-01-01

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

  8. Development of an Efficient Binaural Simulation for the Analysis of Structural Acoustic Data

    NASA Technical Reports Server (NTRS)

    Johnson, Marty E.; Lalime, Aimee L.; Grosveld, Ferdinand W.; Rizzi, Stephen A.; Sullivan, Brenda M.

    2003-01-01

    Applying binaural simulation techniques to structural acoustic data can be very computationally intensive as the number of discrete noise sources can be very large. Typically, Head Related Transfer Functions (HRTFs) are used to individually filter the signals from each of the sources in the acoustic field. Therefore, creating a binaural simulation implies the use of potentially hundreds of real time filters. This paper details two methods of reducing the number of real-time computations required by: (i) using the singular value decomposition (SVD) to reduce the complexity of the HRTFs by breaking them into dominant singular values and vectors and (ii) by using equivalent source reduction (ESR) to reduce the number of sources to be analyzed in real-time by replacing sources on the scale of a structural wavelength with sources on the scale of an acoustic wavelength. The ESR and SVD reduction methods can be combined to provide an estimated computation time reduction of 99.4% for the structural acoustic data tested. In addition, preliminary tests have shown that there is a 97% correlation between the results of the combined reduction methods and the results found with the current binaural simulation techniques

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

    DOE PAGESBeta

    Kral, Zachary; Horn, Walter; Steck, James

    2013-01-01

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

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

    PubMed Central

    Horn, Walter; Steck, James

    2013-01-01

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

  11. Analysis of the acoustic conversion efficiency for infrasound from atmospheric entry of NEO`s

    SciTech Connect

    Whitaker, R.W.; ReVelle, D.O.

    1996-02-01

    ReVelle (1995) has recently presented a summary of available infrasonic signals from near earth objects (NEO`s) that entered the earth`s atmosphere between 1960-1980. We will analyze these signals using a formalism developed by Cox (1958) to calculate the energy of explosive sources in the atmosphere. For each source we will calculate the acoustic conversion efficiency for each source, i.e., the fraction of the original source energy that is available to couple into an acoustic wave. Based on results in Cox with conventional explosions, this quantity is expected to depend weakly on the range from the source. Since this quantity is difficult to estimate using fundamental blast wave theories, we instead use well-known, and independently calibrated, semi-empirical source energy-wave period (at maximum amplitude) scaling relations developed in the 1960-1975 period by the U.S. Air Force to determine the source energy, E{sub s}, from observations. Using E{sub s} and range to the source along with various observed signal and atmospheric properties, the efficiency can be computed, similar calculations have been done for other relevant atmospheric phenomena for low altitude sources. For example, thunder observations at relatively close range have been used by Few and co-workers to determine an acoustic conversion efficiency of about 0.4%. The only previous estimation for meteors was made by Astapovich (1946) who determined the acoustic efficiency to be less than 0.01%. By computing this efficiency factor we hope to predict the expected detection rate of large NEO`s for the proposed CTBT global scale infrasonic array systems, and to establish the rate of false alarms due to natural atmospheric explosions.

  12. Data-driven automated acoustic analysis of human infant vocalizations using neural network tools

    PubMed Central

    Warlaumont, Anne S.; Oller, D. Kimbrough; Buder, Eugene H.; Dale, Rick; Kozma, Robert

    2010-01-01

    Acoustic analysis of infant vocalizations has typically employed traditional acoustic measures drawn from adult speech acoustics, such as f0, duration, formant frequencies, amplitude, and pitch perturbation. Here an alternative and complementary method is proposed in which data-derived spectrographic features are central. 1-s-long spectrograms of vocalizations produced by six infants recorded longitudinally between ages 3 and 11 months are analyzed using a neural network consisting of a self-organizing map and a single-layer perceptron. The self-organizing map acquires a set of holistic, data-derived spectrographic receptive fields. The single-layer perceptron receives self-organizing map activations as input and is trained to classify utterances into prelinguistic phonatory categories (squeal, vocant, or growl), identify the ages at which they were produced, and identify the individuals who produced them. Classification performance was significantly better than chance for all three classification tasks. Performance is compared to another popular architecture, the fully supervised multilayer perceptron. In addition, the network’s weights and patterns of activation are explored from several angles, for example, through traditional acoustic measurements of the network’s receptive fields. Results support the use of this and related tools for deriving holistic acoustic features directly from infant vocalization data and for the automatic classification of infant vocalizations. PMID:20370038

  13. A finite difference analysis of the field present behind an acoustically impenetrable two-layer barrier.

    PubMed

    Hurrell, Andrew M

    2008-06-01

    The interaction of an incident sound wave with an acoustically impenetrable two-layer barrier is considered. Of particular interest is the presence of several acoustic wave components in the shadow region of this barrier. A finite difference model capable of simulating this geometry is validated by comparison to the analytical solution for an idealized, hard-soft barrier. A panel comprising a high air-content closed cell foam backed with an elastic (metal) back plate is then examined. The insertion loss of this panel was found to exceed the dynamic range of the measurement system and was thus acoustically impenetrable. Experimental results from such a panel are shown to contain artifacts not present in the diffraction solution, when acoustic waves are incident upon the soft surface. A finite difference analysis of this experimental configuration replicates the presence of the additional field components. Furthermore, the simulated results allow the additional components to be identified as arising from the S(0) and A(0) Lamb modes traveling in the elastic plate. These Lamb mode artifacts are not found to be present in the shadow region when the acoustic waves are incident upon the elastic surface. PMID:18537372

  14. [EFFECTS OF MUSIC-ACOUSTIC SIGNALS, ONLINE CONTROLLED BY EEG OSCILLATORS OF THE SUBJECT].

    PubMed

    Fedotchev, A I; Bondar, A T; Bakhchina, A V; Parin, S B; Polevaya, S A; Radchenko, G S

    2015-08-01

    The effects of 2 variants of the method of musical EEG neurofeedback, in which the dominant spectral components of subject's EEG (EEG oscillators) are online converted to music-like signals similar by timbre to flute sounds, have been studied. In the first case, these music-like signals were smoothly varying by the pitch and intensity in accordance with the current amplitude of the EEG oscillator. In the second case, the same variations of flute-like sound were accompanied by such musical element as rhythm. After the single exposure, the modifications of subject's brain activity and positive changes in psycho-physiological state of the subject have been found. Particularly pronounced effects were observed under rhythmically organized music-like stimuli. PMID:26591592

  15. Technique for the suppression of three-pass signals in surface-acoustic-wave filters

    NASA Astrophysics Data System (ADS)

    Paskhin, V. M.; Sandler, M. S.; Sveshnikov, B. V.

    1981-12-01

    It is shown analytically that for any thickness of the interdigital transducer (IDT) electrodes, the level of three-pass signal suppression can be made appreciable by the proper choice of complex electrical loads of the transducers. These loads are shown to depend on the IDT electrode thickness. The theoretical conclusion is verified experimentally by studying an SAW filter with aluminum IDT on an ST-cut quartz substrate.

  16. A comprehensive strategy for the analysis of acoustic compressibility and optical deformability on single cells

    NASA Astrophysics Data System (ADS)

    Yang, Tie; Bragheri, Francesca; Nava, Giovanni; Chiodi, Ilaria; Mondello, Chiara; Osellame, Roberto; Berg-Sørensen, Kirstine; Cristiani, Ilaria; Minzioni, Paolo

    2016-04-01

    We realized an integrated microfluidic chip that allows measuring both optical deformability and acoustic compressibility on single cells, by optical stretching and acoustophoresis experiments respectively. Additionally, we propose a measurement protocol that allows evaluating the experimental apparatus parameters before performing the cell-characterization experiments, including a non-destructive method to characterize the optical force distribution inside the microchannel. The chip was used to study important cell-mechanics parameters in two human breast cancer cell lines, MCF7 and MDA-MB231. Results indicate that MDA-MB231 has both higher acoustic compressibility and higher optical deformability than MCF7, but statistical analysis shows that optical deformability and acoustic compressibility are not correlated parameters. This result suggests the possibility to use them to analyze the response of different cellular structures. We also demonstrate that it is possible to perform both measurements on a single cell, and that the order of the two experiments does not affect the retrieved values.

  17. Analysis of random structure-acoustic interaction problems using coupled boundary element and finite element methods

    NASA Technical Reports Server (NTRS)

    Mei, Chuh; Pates, Carl S., III

    1994-01-01

    A coupled boundary element (BEM)-finite element (FEM) approach is presented to accurately model structure-acoustic interaction systems. The boundary element method is first applied to interior, two and three-dimensional acoustic domains with complex geometry configurations. Boundary element results are very accurate when compared with limited exact solutions. Structure-interaction problems are then analyzed with the coupled FEM-BEM method, where the finite element method models the structure and the boundary element method models the interior acoustic domain. The coupled analysis is compared with exact and experimental results for a simplistic model. Composite panels are analyzed and compared with isotropic results. The coupled method is then extended for random excitation. Random excitation results are compared with uncoupled results for isotropic and composite panels.

  18. Signal analysis of behavioral and molecular cycles

    PubMed Central

    Levine, Joel D; Funes, Pablo; Dowse, Harold B; Hall, Jeffrey C

    2002-01-01

    Background Circadian clocks are biological oscillators that regulate molecular, physiological, and behavioral rhythms in a wide variety of organisms. While behavioral rhythms are typically monitored over many cycles, a similar approach to molecular rhythms was not possible until recently; the advent of real-time analysis using transgenic reporters now permits the observations of molecular rhythms over many cycles as well. This development suggests that new details about the relationship between molecular and behavioral rhythms may be revealed. Even so, behavioral and molecular rhythmicity have been analyzed using different methods, making such comparisons difficult to achieve. To address this shortcoming, among others, we developed a set of integrated analytical tools to unify the analysis of biological rhythms across modalities. Results We demonstrate an adaptation of digital signal analysis that allows similar treatment of both behavioral and molecular data from our studies of Drosophila. For both types of data, we apply digital filters to extract and clarify details of interest; we employ methods of autocorrelation and spectral analysis to assess rhythmicity and estimate the period; we evaluate phase shifts using crosscorrelation; and we use circular statistics to extract information about phase. Conclusion Using data generated by our investigation of rhythms in Drosophila we demonstrate how a unique aggregation of analytical tools may be used to analyze and compare behavioral and molecular rhythms. These methods are shown to be versatile and will also be adaptable to further experiments, owing in part to the non-proprietary nature of the code we have developed. PMID:11825337

  19. Continuous measurements of suspended sediment loads using dual frequency acoustic Doppler profile signals

    NASA Astrophysics Data System (ADS)

    Antonini, Alessandro; Guerrero, Massimo; Rüther, Nils; Stokseth, Siri

    2016-04-01

    A huge thread to Hydropower plants (HPP) is incoming sediments in suspension from the rivers upstream. The sediments settle in the reservoir and reduce the effective head as well as the volume and reduce consequently the lifetime of the reservoir. In addition are the fine sediments causing severe damages to turbines and infrastructure of a HPP. For estimating the amount of in-coming sediments in suspension and the consequent planning of efficient counter measures, it is essential to monitor the rivers within the catchment of the HPP for suspended sediments. This work is considerably time consuming and requires highly educated personnel and is therefore expensive. Surrogate-indirect methods using acoustic and optic devices have bee developed since the last decades that may be efficiently applied for the continuous monitoring of suspended sediment loads. The presented study proposes therefore to establish a research station at a cross section of a river which is the main tributary to a reservoir of a HPP and equip this station with surrogate as well as with common method of measuring suspended load concentrations and related flow discharge and level. The logger at the research station delivers data automatically to a server. Therefore it is ensured that also large flood events are covered. Data during flood are of high interest to the HPP planners since they carried the most part of the sediment load in a hydrological year. Theses peaks can hardly be measured with common measurement methods. Preliminary results of the wet season 2015/2016 are presented. The data gives insight in the applicable range, in terms of scattering particles concentration-average size and corresponding flow discharge and level, eventually enabling the study of suspended sediment load-water flow correlations during peak events. This work is carried out as part of a larger research project on sustainable hydro power plants exposed to high sediment yield, SediPASS. SediPASS is funded by the

  20. Continuous wavelet-transform analysis of photoacoustic signal waveform to determine optical absorption coefficient

    NASA Astrophysics Data System (ADS)

    Hirasawa, T.; Ishihara, M.; Tsujita, K.; Hirota, K.; Irisawa, K.; Kitagaki, M.; Fujita, M.; Kikuchi, M.

    2012-02-01

    In photo-acoustic (PA) imaging, valuable medical applications based on optical absorption spectrum such as contrast agent imaging and blood oxygen saturation measurement have been investigated. In these applications, there is an essential requirement to determine optical absorption coefficients accurately. In present, PA signal intensities have been commonly used to determine optical absorption coefficients. This method achieves practical accuracy by combining with radiative transfer analysis. However, time consumption of radiative transfer analysis and effects of signal generation efficiencies were problems of this method. In this research, we propose a new method to determine optical absorption coefficients using continuous wavelet transform (CWT). We used CWT to estimate instantaneous frequencies of PA signals which reflects optical absorption distribution. We validated the effectiveness of CWT in determination of optical absorption coefficients through an experiment. In the experiment, planar shaped samples were illuminated to generate PA signal. The PA signal was measured by our fabricated PA probe in which an optical fiber and a ring shaped P(VDFTrFE) ultrasound sensor were coaxially aligned. Optical properties of samples were adjusted by changing the concentration of dye solution. Tunable Ti:Sapphire laser (690 - 1000 nm) was used as illumination source. As a result, we confirmed strong correlation between optical absorption coefficients of samples and the instantaneous frequency of PA signal obtained by CWT. Advantages of this method were less interference of light transfer and signal generation efficiency.

  1. A Quantitative Analysis of Pulsed Signals Emitted by Wild Bottlenose Dolphins.

    PubMed

    Luís, Ana Rita; Couchinho, Miguel N; Dos Santos, Manuel E

    2016-01-01

    Common bottlenose dolphins (Tursiops truncatus), produce a wide variety of vocal emissions for communication and echolocation, of which the pulsed repertoire has been the most difficult to categorize. Packets of high repetition, broadband pulses are still largely reported under a general designation of burst-pulses, and traditional attempts to classify these emissions rely mainly in their aural characteristics and in graphical aspects of spectrograms. Here, we present a quantitative analysis of pulsed signals emitted by wild bottlenose dolphins, in the Sado estuary, Portugal (2011-2014), and test the reliability of a traditional classification approach. Acoustic parameters (minimum frequency, maximum frequency, peak frequency, duration, repetition rate and inter-click-interval) were extracted from 930 pulsed signals, previously categorized using a traditional approach. Discriminant function analysis revealed a high reliability of the traditional classification approach (93.5% of pulsed signals were consistently assigned to their aurally based categories). According to the discriminant function analysis (Wilk's Λ = 0.11, F3, 2.41 = 282.75, P < 0.001), repetition rate is the feature that best enables the discrimination of different pulsed signals (structure coefficient = 0.98). Classification using hierarchical cluster analysis led to a similar categorization pattern: two main signal types with distinct magnitudes of repetition rate were clustered into five groups. The pulsed signals, here described, present significant differences in their time-frequency features, especially repetition rate (P < 0.001), inter-click-interval (P < 0.001) and duration (P < 0.001). We document the occurrence of a distinct signal type-short burst-pulses, and highlight the existence of a diverse repertoire of pulsed vocalizations emitted in graded sequences. The use of quantitative analysis of pulsed signals is essential to improve classifications and to better assess the contexts of

  2. A Quantitative Analysis of Pulsed Signals Emitted by Wild Bottlenose Dolphins

    PubMed Central

    Couchinho, Miguel N.; dos Santos, Manuel E.

    2016-01-01

    Common bottlenose dolphins (Tursiops truncatus), produce a wide variety of vocal emissions for communication and echolocation, of which the pulsed repertoire has been the most difficult to categorize. Packets of high repetition, broadband pulses are still largely reported under a general designation of burst-pulses, and traditional attempts to classify these emissions rely mainly in their aural characteristics and in graphical aspects of spectrograms. Here, we present a quantitative analysis of pulsed signals emitted by wild bottlenose dolphins, in the Sado estuary, Portugal (2011–2014), and test the reliability of a traditional classification approach. Acoustic parameters (minimum frequency, maximum frequency, peak frequency, duration, repetition rate and inter-click-interval) were extracted from 930 pulsed signals, previously categorized using a traditional approach. Discriminant function analysis revealed a high reliability of the traditional classification approach (93.5% of pulsed signals were consistently assigned to their aurally based categories). According to the discriminant function analysis (Wilk’s Λ = 0.11, F3, 2.41 = 282.75, P < 0.001), repetition rate is the feature that best enables the discrimination of different pulsed signals (structure coefficient = 0.98). Classification using hierarchical cluster analysis led to a similar categorization pattern: two main signal types with distinct magnitudes of repetition rate were clustered into five groups. The pulsed signals, here described, present significant differences in their time-frequency features, especially repetition rate (P < 0.001), inter-click-interval (P < 0.001) and duration (P < 0.001). We document the occurrence of a distinct signal type–short burst-pulses, and highlight the existence of a diverse repertoire of pulsed vocalizations emitted in graded sequences. The use of quantitative analysis of pulsed signals is essential to improve classifications and to better assess the contexts

  3. Eigenfunction analysis of stochastic backscatter for characterization of acoustic aberration in medical ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Varslot, Trond; Krogstad, Harald; Mo, Eirik; Angelsen, Bjørn A.

    2004-06-01

    Presented here is a characterization of aberration in medical ultrasound imaging. The characterization is optimal in the sense of maximizing the expected energy in a modified beamformer output of the received acoustic backscatter. Aberration correction based on this characterization takes the form of an aberration correction filter. The situation considered is frequently found in applications when imaging organs through a body wall: aberration is introduced in a layer close to the transducer, and acoustic backscatter from a scattering region behind the body wall is measured at the transducer surface. The scattering region consists of scatterers randomly distributed with very short correlation length compared to the acoustic wavelength of the transmit pulse. The scatterer distribution is therefore assumed to be δ correlated. This paper shows how maximizing the expected energy in a modified beamformer output signal naturally leads to eigenfunctions of a Fredholm integral operator, where the associated kernel function is a spatial correlation function of the received stochastic signal. Aberration characterization and aberration correction are presented for simulated data constructed to mimic aberration introduced by the abdominal wall. The results compare well with what is obtainable using data from a simulated point source.

  4. Complex multivariate sexual selection on male acoustic signaling in a wild population of Teleogryllus commodus.

    PubMed

    Bentsen, Caroline L; Hunt, John; Jennions, Michael D; Brooks, Robert

    2006-04-01

    Mate choice may impose both linear (i.e., directional) and nonlinear (i.e., quadratic and correlational) sexual selection on advertisement traits. Traditionally, mate recognition and sensory tuning have been thought to impose stabilizing (i.e., negative quadratic) sexual selection, whereas adaptive mate choice effects directional selection. It has been suggested that adaptive choice may exert positive quadratic and/or correlational sexual selection. Earlier, we showed that five structural components of the advertisement call of male field crickets (Teleogryllus commodus) were under multivariate stabilizing selection under laboratory conditions. Here we experimentally estimate selection on these five traits plus a measure of calling activity (the number of repeats in a looped bout of calling) in the field. There was general support for multivariate stabilizing selection on call structure, and calling activity was under strong positive directional selection, as predicted for a signal of genetic quality. There was, however, also appreciable correlational selection, suggesting an interaction between male call structure and calling effort. Interestingly, selection for short interbout durations of silence favored longer intercall durations in the field, in contrast to results from continuous looped call playback in the laboratory. We discuss the general importance of nonlinear selection in the honest signaling of genetic quality. PMID:16670989

  5. Vibroacoustic analysis and experimental validation of the structural responses of NASA Mars Exploration Rover spacecraft due to acoustic launch load

    NASA Technical Reports Server (NTRS)

    Hwang, H. J.

    2003-01-01

    Structural responses of a spacecraft during liftoff are dominated by the intense acoustic pressure field imping on the exterior of the launch vehicle. Statistical Energy Analysis model of the NASA Mars Exploration Rover spacecraft has been developed and the SEA model was analyzed to predict vibroacoustic responses of the spacecraft under the diffuse acoustic loading condition.

  6. Characterizing noise in nonhuman vocalizations: Acoustic analysis and human perception of barks by coyotes and dogs

    NASA Astrophysics Data System (ADS)

    Riede, Tobias; Mitchell, Brian R.; Tokuda, Isao; Owren, Michael J.

    2005-07-01

    Measuring noise as a component of mammalian vocalizations is of interest because of its potential relevance to the communicative function. However, methods for characterizing and quantifying noise are less well established than methods applicable to harmonically structured aspects of signals. Using barks of coyotes and domestic dogs, we compared six acoustic measures and studied how they are related to human perception of noisiness. Measures of harmonic-to-noise-ratio (HNR), percent voicing, and shimmer were found to be the best predictors of perceptual rating by human listeners. Both acoustics and perception indicated that noisiness was similar across coyote and dog barks, but within each species there was significant variation among the individual vocalizers. The advantages and disadvantages of the various measures are discussed.

  7. Analysis of an existing experiment on the interaction of acoustic waves with a laminar boundary layer

    NASA Technical Reports Server (NTRS)

    Schopper, M. R.

    1982-01-01

    The hot-wire anemometer amplitude data contained in the 1977 report of P. J. Shapiro entitled, ""The Influence of Sound Upon Laminar Boundary'' were reevaluated. Because the low-Reynolds number boundary layer disturbance data were misinterpreted, an effort was made to improve the corresponding disturbance growth rate curves. The data are modeled as the sum of upstream and downstream propagating acoustic waves and a wave representing the Tollmien-Schlichting (TS) wave. The amplitude and phase velocity of the latter wave were then adjusted so that the total signal reasonably matched the amplitude and phase angle hot-wire data along the plate laminar boundary layer. The revised rates show growth occurring further upstream than Shapiro found. It appears that the premature growth is due to the adverse pressure gradient created by the shape of the plate. Basic elements of sound propagation in ducts and the experimental and theoretical acoustic-stability literature are reviewed.

  8. Risk Factors of Acoustic Neuroma: Systematic Review and Meta-Analysis

    PubMed Central

    Chen, Mantao; Fan, Zuoxu; Cao, Fei; Wang, Liang

    2016-01-01

    Purpose Many epidemiological studies have investigated environmental risk factors for the development of acoustic neuroma. However, these results are controversial. We conducted a meta-analysis of case-control studies to identify any potential relationship between history of noise exposure, smoking, allergic diseases, and risk of acoustic neuroma. Materials and Methods We searched PubMed to identify relevant articles. Two researchers evaluated the eligibility and extracted the data independently. Results Eleven case-control studies were included in our meta-analysis. Acoustic neuroma was found to be associated with leisure noise exposure [odds ratio (OR)=1.33, 95% confidence interval (CI): 1.05–1.68], but not with occupational noise exposure and ever noise exposure (OR=1.20, 95% CI: 0.84–1.72 and OR=1.15, 95% CI: 0.80–1.65). The OR of acoustic neuroma for ever (versus never) smoking was 0.53 (95% CI: 0.30–0.94), while the subgroup analysis indicated ORs of 0.95 (95% CI: 0.81–1.10) and 0.49 (95% CI: 0.41–0.59) for ex-smoker and current smoker respectively. The ORs for asthma, eczema, and seasonal rhinitis were 0.98 (95% CI: 0.80–1.18), 0.91 (95% CI: 0.76–1.09), and 1.52 (95% CI: 0.90–2.54), respectively. Conclusion Our meta-analysis is suggestive of an elevated risk of acoustic neuroma among individuals who were ever exposed to leisure noise, but not to occupational noise. Our study also indicated a lower acoustic neuroma risk among ever and current cigarette smokers than never smokers, while there was no significant relationship for ex-smokers. No significant associations were found between acoustic neuroma and history of any allergic diseases, such as asthma, eczema, and seasonal rhinitis. PMID:26996581

  9. Contribution of the 3-D visualization of acoustic borehole signals (full waveforms) to a quick formation evaluation

    NASA Astrophysics Data System (ADS)

    Rousseau, André; Jeantet, Dominique

    1994-02-01

    Logging and continuous coring are carried out when drilling and looking for materials such as gravels, sand, and clay or in order to evaluate the fracture state of a deep site intended for waste storage. However, in some cases of non-consolidated formations, the results may be disappointing because of the borehole conditions. Full waveforms, as seismic signals, provide information about physical parameters of the grounds crossed by the sonic tool, and this information is almost independent of borehole conditions. Traditional displays in variable area or density show the wave arrival times and the frequencies with depth; for variable density, a color scale permits to see clustered instantaneous phases. In order to determine precisely and simultaneously the three signal parameters (arrival time, frequency, and amplitude) in the depth-propagation time domain, a 3-D visualization software has been developed. The "view" parameters, which give a nice display of the 3-D→2-D projection of the signals in a parallel perspectives relative to depth, are estimated on the monitor screen in an interactive way. A larger size version of the software is available for displaying in detail the acoustic signals for the whole borehole. However, this program needs a large computer, and the maximum size of the drawing depends on the computer memory available for use. The comparison between traditional and 3-D displays shows that without previous preprocessing, the 3-D visualization (1) shows the very small and continuous variations of amplitude (and, therefore, of attenuation) with depth better; and (2) can bring out interferences and "energetic peaks" by simply changing the "view" parameters. As the attenuation of the different waves is directly determined, fresh zones can be distinguished immediately from fracture zones and hard ground from soft ground. The geometry of major fracturing can be deduced directly from graphical representation; i.e. open or closed, and horizontal or

  10. High signal-to-noise ratio acoustic sensor using phase shifted gratings interrogated by the Pound-Drever-Hall technique

    NASA Astrophysics Data System (ADS)

    Kung, Peter; Comanici, Maria I.

    2015-03-01

    Optical fiber is made of glass, an insulator, and thus it is immune to strong electromagnetic interference. Therefore, fiber optics is a technology ideally suitable for sensing of partial discharge (PD) both in transformers and generators. Extensive efforts have been used to develop a cost effective solution for detecting partial discharge, which generates acoustic emission, with signals ranging from 30 kHz to 200 kHz. The requirement is similar to fiber optics Hydro Phone, but at higher frequencies. There are several keys to success: there must be at least 60 dB sig