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Sample records for acoustic mass sensor

  1. Longitudinal bulk acoustic mass sensor

    SciTech Connect

    Hales, J. H.; Teva, J.; Boisen, A.; Davis, Z. J.

    2009-07-20

    A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10{sup -15} g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise in the currently applied measurement system allows for a minimum detectable mass of 0.5 fg in air.

  2. Longitudinal bulk acoustic mass sensor

    NASA Astrophysics Data System (ADS)

    Hales, J. H.; Teva, J.; Boisen, A.; Davis, Z. J.

    2009-07-01

    A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10-15 g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise in the currently applied measurement system allows for a minimum detectable mass of 0.5 fg in air.

  3. Sensitivity study of multilayer thin-film bulk acoustic resonator for mass sensor application

    NASA Astrophysics Data System (ADS)

    Liu, Haiqiang; Li, Fang; Qin, Lifeng; Wang, Qing-Ming

    2016-10-01

    The sensitivity of multilayer thin-film bulk acoustic resonators (MTFBARs) used as mass sensors is investigated. MTFBAR sensors with the structure of a mass-sensitive layer/electrode layer/piezo layer/electrode layer were used. Two methods, one using electric impedance and the other displacement, were adopted for the determination of sensitivity. Simulation results show that the two methods agree well, and the characteristic acoustic impedance and thickness of the non-piezo layers strongly affect mass sensitivity. It was found that high acoustic impedance in the non-piezo layer is not helpful for sensitivity improvement. Sensitivity is improved by choosing an appropriate thickness for the low acoustic impedance non-piezo layer, and the maximum sensitivity can be obtained by choosing suitable thickness combinations for the layers. Moreover, it was found that MTFBAR quality factor and sensitivity are simultaneously improved by adopting a high-quality-factor non-piezo layer with low acoustic impedance for an air working environment, whereas a balance between quality factor and sensitivity is found through optimization of the non-piezo layers for a water working environment. These results can be used for the design and application of MTFBAR mass sensors.

  4. Multilayer graphene electrodes for one-port surface acoustic wave resonator mass sensor

    NASA Astrophysics Data System (ADS)

    Leong, Ainan; Swamy, Varghese; Ramakrishnan, N.

    2017-02-01

    A one-port surface acoustic wave (SAW) resonator mass sensor composed of multilayer graphene (MLG) electrodes was investigated by the finite element method (FEM) and analyses were carried out to study the enhancement of sensitivity and the secondary effects caused by MLG electrodes on the performance of the resonator. Unlike metal electrodes, MLG electrode offers elastic loading to the contact surface, as evidenced by the increase in the surface velocity of the SAW device. In terms of the sensitivity of the mass sensor, MLG electrode showed the largest center frequency shift in response to a change in mass loading, as well as when used as a gas sensor to detect volatile organic compounds (VOCs). Also, MLG electrodes offered the least triple transit signal (TTS) and bulk acoustic wave (BAW) generations compared with Al and Au–Cr electrodes. Thus, the one-port SAW resonator with graphene electrodes not only possesses excellent performance characteristics but also gives rise to new opportunities in the development of highly sensitive mass sensors.

  5. Mass sensitivity analysis and designing of surface acoustic wave resonators for chemical sensors

    NASA Astrophysics Data System (ADS)

    Kshetrimayum, Roshan; Yadava, R. D. S.; Tandon, R. P.

    2009-05-01

    The sensitivity of surface acoustic wave (SAW) chemical sensors depends on several factors such as the frequency and phase point of SAW device operation, sensitivity of the SAW velocity to surface mass loading, sensitivity of the SAW oscillator resonance to the loop phase shift, film thickness and oscillator electronics. This paper analyzes the influence of the phase point of operation in SAW oscillator sensors based on two-port resonator devices. It is found that the mass sensitivity will be enhanced if the SAW device has a nonlinear dependence on the frequency (delay ~ frequency-1). This requires the device to generate and operate in a ωτg(ω) = const region in the device passband, where ω denotes the angular frequency of oscillation and τg(ω) denotes the phase slope of the SAW resonator device. A SAW coupled resonator filter (CRF) that take advantage of mode coupling is considered in realizing such a device to help in shaping the phase transfer characteristics of a high mass sensitivity sensor. The device design and simulation results are presented within the coupling-of-modes formalism.

  6. Investigation into mass loading sensitivity of sezawa wave mode-based surface acoustic wave sensors.

    PubMed

    Mohanan, Ajay Achath; Islam, Md Shabiul; Ali, Sawal Hamid; Parthiban, R; Ramakrishnan, N

    2013-02-06

    In this work mass loading sensitivity of a Sezawa wave mode based surface acoustic wave (SAW) device is investigated through finite element method (FEM) simulation and the prospects of these devices to function as highly sensitive SAW sensors is reported. A ZnO/Si layered SAW resonator is considered for the simulation study. Initially the occurrence of Sezawa wave mode and displacement amplitude of the Rayleigh and Sezawa wave mode is studied for lower ZnO film thickness. Further, a thin film made of an arbitrary material is coated over the ZnO surface and the resonance frequency shift caused by mass loading of the film is estimated. It was observed that Sezawa wave mode shows significant sensitivity to change in mass loading and has higher sensitivity (eight times higher) than Rayleigh wave mode for the same device configuration. Further, the mass loading sensitivity was observed to be greater for a low ZnO film thickness to wavelength ratio. Accordingly, highly sensitive SAW sensors can be developed by coating a sensing medium over a layered SAW device and operating at Sezawa mode resonance frequency. The sensitivity can be increased by tuning the ZnO film thickness to wavelength ratio.

  7. Directional Acoustic Density Sensor

    DTIC Science & Technology

    2010-09-13

    fluctuations of fluid density at a point . (2) DESCRIPTION OF THE PRIOR ART [0004] Conventional vector sensors measure particle velocity, v (vx,Vytvz...dipole-type or first order sensor that is realized by measuring particle velocity at a point , (which is the vector sensor sensing approach for...underwater sensors), or by measuring the gradient of the acoustic pressure at two closely spaced (less than the wavelength of an acoustic wave) points as it

  8. Mass Sensitivity Optimization of a Surface Acoustic Wave Sensor Incorporating a Resonator Configuration

    PubMed Central

    Hao, Wenchang; Liu, Jiuling; Liu, Minghua; Liang, Yong; He, Shitang

    2016-01-01

    The effect of the sensitive area of the two-port resonator configuration on the mass sensitivity of a Rayleigh surface acoustic wave (R-SAW) sensor was investigated theoretically, and verified in experiments. A theoretical model utilizing a 3-dimensional finite element method (FEM) approach was established to extract the coupling-of-modes (COM) parameters in the absence and presence of mass loading covering the electrode structures. The COM model was used to simulate the frequency response of an R-SAW resonator by a P-matrix cascading technique. Cascading the P-matrixes of unloaded areas with mass loaded areas, the sensitivity for different sensitive areas was obtained by analyzing the frequency shift. The performance of the sensitivity analysis was confirmed by the measured responses from the silicon dioxide (SiO2) deposited on different sensitive areas of R-SAW resonators. It is shown that the mass sensitivity varies strongly for different sensitive areas, and the optimal sensitive area lies towards the center of the device. PMID:27104540

  9. Mass Sensitivity Optimization of a Surface Acoustic Wave Sensor Incorporating a Resonator Configuration.

    PubMed

    Hao, Wenchang; Liu, Jiuling; Liu, Minghua; Liang, Yong; He, Shitang

    2016-04-20

    The effect of the sensitive area of the two-port resonator configuration on the mass sensitivity of a Rayleigh surface acoustic wave (R-SAW) sensor was investigated theoretically, and verified in experiments. A theoretical model utilizing a 3-dimensional finite element method (FEM) approach was established to extract the coupling-of-modes (COM) parameters in the absence and presence of mass loading covering the electrode structures. The COM model was used to simulate the frequency response of an R-SAW resonator by a P-matrix cascading technique. Cascading the P-matrixes of unloaded areas with mass loaded areas, the sensitivity for different sensitive areas was obtained by analyzing the frequency shift. The performance of the sensitivity analysis was confirmed by the measured responses from the silicon dioxide (SiO₂) deposited on different sensitive areas of R-SAW resonators. It is shown that the mass sensitivity varies strongly for different sensitive areas, and the optimal sensitive area lies towards the center of the device.

  10. Highly sensitive detection of organophosphorus pesticides by acetylcholinesterase-coated thin film bulk acoustic resonator mass-loading sensor.

    PubMed

    Chen, Da; Wang, Jingjing; Xu, Yan; Li, Dehua; Zhang, Luyin; Li, Zhaoxin

    2013-03-15

    An acetylcholinesterase-coated thin film bulk acoustic resonator has been developed for the detection of organophosphorus pesticides. The thin film bulk acoustic resonator acts as a robust mass-sensitive transducer for bio-sensing. This device works in thickness shear mode with a resonance at 1.97 GHz. The detection is based on the inhibitory effects of organophosphorus compounds on the enzymatic activity of the acetylcholinesterase immobilized on one of the faces of the acoustic resonator. The enzyme reaction in the substrate solution and the inhibitory effect is observed are real time by measuring the frequency shift. The presence of organophosphorus pesticides can be detected from the diminution of the frequency shift compared with the levels found in their absence. The device exhibits linear responses, good reproducibility, simple operation, portability and a low detection limit of 5.3×10(-11) M for paraoxon. The detection results of organophosphorus pesticide residues in practical samples show that the proposed sensor has the feasibility and sensing accuracy comparable to gas chromatography.

  11. An acoustic glucose sensor.

    PubMed

    Hu, Ruifen; Stevenson, Adrian C; Lowe, Christopher R

    2012-05-15

    In vivo glucose monitoring is required for tighter glycaemic control. This report describes a new approach to construct a miniature implantable device based on a magnetic acoustic resonance sensor (MARS). A ≈ 600-800 nm thick glucose-responsive poly(acrylamide-co-3-acrylamidophenylboronic acid) (poly(acrylamide-co-3-APB)) film was polymerised on the quartz disc (12 mm in diameter and 0.25 mm thick) of the MARS. The swelling/shrinking of the polymer film induced by the glucose binding to the phenylboronate caused changes in the resonance amplitude of the quartz disc in the MARS. A linear relationship between the response of the MARS and the glucose concentration in the range ≈ 0-15 mM was observed, with the optimum response of the MARS sensor being obtained when the polymer films contained ≈ 20 mol% 3-APB. The MARS glucose sensor also functioned under flow conditions (9 μl/min) with a response almost identical to the sensor under static or non-flow conditions. The results suggest that the MARS could offer a promising strategy for developing a small subcutaneously implanted continuous glucose monitor.

  12. Mass Sensor

    SciTech Connect

    Adams, B.E.

    2001-01-18

    The purpose of this CRADA was to use Honeywell's experience in low temperature cofire ceramics and traditional ceramics to assemble a relatively low-cost, mass-producible miniature mass analyzer. The specific design, given to us by Mass Sensors, LLC, was used to test for helium. The direct benefit for the participant was to have a prototype unit assembled for the purpose of proof of concept and the ability to secure venture capital investors. From that, the company would begin producing their own product for sale. The consumer/taxpayer benefits come from the wide variety of industries that can utilize this technology to improve quality of life. Medical industry can use this technology to improve diagnostic ability; manufacturing industry can use it for improved air, water, and soil monitoring to minimize pollution; and the law enforcement community can use this technology for identification of substances. These are just a few examples of the benefit of this technology. The benefits to DOE were in the area of process improvement for cofire and ceramic materials. From this project we demonstrated nonlinear thickfilm fine lines and spaces that were 5-mil wide with 5-mil spaces; determined height-to diameter-ratios for punched and filled via holes; demonstrated the ability to punch and fill 5-mil microvias; developed and demonstrated the capability to laser cut difficult geometries in 40-mil ceramic; developed and demonstrated coupling LTCC with standard alumina and achieving hermetic seals; developed and demonstrated three-dimensional electronic packaging concepts; and demonstrated printing variable resistors within 1% of the nominal value and within a tightly defined ratio. The capability of this device makes it invaluable for many industries. The device could be used to monitor air samples around manufacturing plants. It also could be used for monitoring automobile exhaust, for doing blood gas analysis, for sampling gases being emitted by volcanoes, for studying

  13. Acoustic/Magnetic Stress Sensor

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.; Namkung, M.

    1986-01-01

    High-resolution sensor fast, portable, does not require permanent bonding to structure. Sensor measures nondestructively type (compressive or tensile) and magnitude of stresses and stress gradients present in class of materials. Includes precise high-resolution acoustic interferometer, sending acoustic transducer, receiving acoustic transducer, electromagnet coil and core, power supply, and magnetic-field-measuring device such as Hall probe. This measurement especially important for construction and applications where steel is widely used. Sensor useful especially for nondestructive evaluation of stress in steel members because of portability, rapid testing, and nonpermanent installation.

  14. Frustrated total internal reflection acoustic field sensor

    DOEpatents

    Kallman, Jeffrey S.

    2000-01-01

    A frustrated total internal reflection acoustic field sensor which allows the acquisition of the acoustic field over an entire plane, all at once. The sensor finds use in acoustic holography and acoustic diffraction tomography. For example, the sensor may be produced by a transparent plate with transparent support members tall enough to support one or more flexible membranes at an appropriate height for frustrated total internal reflection to occur. An acoustic wave causes the membrane to deflect away from its quiescent position and thus changes the amount of light that tunnels through the gap formed by the support members and into the membrane, and so changes the amount of light reflected by the membrane. The sensor(s) is illuminated by a uniform tight field, and the reflection from the sensor yields acoustic wave amplitude and phase information which can be picked up electronically or otherwise.

  15. High-sensitivity fiber optic acoustic sensors

    NASA Astrophysics Data System (ADS)

    Lu, Ping; Liu, Deming; Liao, Hao

    2016-11-01

    Due to the overwhelming advantages compared with traditional electronicsensors, fiber-optic acoustic sensors have arisen enormous interest in multiple disciplines. In this paper we present the recent research achievements of our group on fiber-optic acoustic sensors. The main point of our research is high sensitivity interferometric acoustic sensors, including Michelson, Sagnac, and Fabry-Pérot interferometers. In addition, some advanced technologies have been proposed for acoustic or acoustic pressure sensing such as single-mode/multimode fiber coupler, dual FBGs and multi-longitudinal mode fiber laser based acoustic sensors. Moreover, our attention we have also been paid on signal demodulation schemes. The intensity-based quadrature point (Q-point) demodulation, two-wavelength quadrature demodulation and symmetric 3×3 coupler methodare discussed and compared in this paper.

  16. Acoustic pressure-vector sensor array

    NASA Astrophysics Data System (ADS)

    Huang, Dehua; Elswick, Roy C.; McEachern, James F.

    2004-05-01

    Pressure-vector sensors measure both scalar and vector components of the acoustic field. December 2003 measurements at the NUWC Seneca Lake test facility verify previous observations that acoustic ambient noise spectrum levels measured by acoustic intensity sensors are reduced relative to either acoustic pressure or acoustic vector sensor spectrum levels. The Seneca measurements indicate a reduction by as much as 15 dB at the upper measurement frequency of 2500 Hz. A nonlinear array synthesis theory for pressure-vector sensors will be introduced that allows smaller apertures to achieve narrow beams. The significantly reduced ambient noise of individual pressure-vector elements observed in the ocean by others, and now at Seneca Lake, should allow a nonlinearly combined array to detect significantly lower levels than has been observed in previous multiplicative processing of pressure sensors alone. Nonlinear array synthesis of pressure-vector sensors differs from conventional super-directive algorithms that linearly combine pressure elements with positive and negative weights, thereby reducing the sensitivity of conventional super-directive arrays. The much smaller aperture of acoustic pressure-vector sensor arrays will be attractive for acoustic systems on underwater vehicles, as well as for other applications that require narrow beam acoustic receivers. [The authors gratefully acknowledge the support of ONR and NUWC.

  17. Acoustic Environment Simulation Study; Acoustic Intrusion Sensor Performance.

    DTIC Science & Technology

    1983-01-01

    RD-R149 245 ACOUSTIC ENVIRONMENT SIMULATION STUDY; ACOUSTIC is INTRUSION SENSOR PERFORMANCE(U) TIME SERIES ASSOCIATES PALO ALTO CA L ENOCHSON ET AL...ACOUSTIC ENVIRONMENT SIMULATION STUDY PREPARED BY: LOREN ENOCHSON TIME SERIES ASSOCIATES 920 WEST 33RD AVENUE SPOKANE, WA 99203 PREPARED FOR: NAVAL... TIME COVERED 5A0pA OF 1 jeamonth, Day) S, 54 ( 4UNT ,inal; .. na, F ROM TO o . !L,,Nv; REJa- ,GE U -. ,16. SUPPLEMENTARY NOTATION COSATI CODES 18

  18. Improved Calibration Of Acoustic Plethysmographic Sensors

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J.; Davis, David C.

    1993-01-01

    Improved method of calibration of acoustic plethysmographic sensors involves acoustic-impedance test conditions like those encountered in use. Clamped aluminum tube holds source of sound (hydrophone) inside balloon. Test and reference sensors attached to outside of balloon. Sensors used to measure blood flow, blood pressure, heart rate, breathing sounds, and other vital signs from surfaces of human bodies. Attached to torsos or limbs by straps or adhesives.

  19. Surface-acoustic-wave (SAW) flow sensor

    NASA Astrophysics Data System (ADS)

    Joshi, Shrinivas G.

    1991-03-01

    The use of a surface-acoustic-wave (SAW) device to measure the rate of gas flow is described. A SAW oscillator heated to a suitable temperature above ambient is placed in the path of a flowing gas. Convective cooling caused by the gas flow results in a change in the oscillator frequency. A 73-MHz oscillator fabricated on 128 deg rotated Y-cut lithium niobate substrate and heated to 55 C above ambient shows a frequency variation greater than 142 kHz for flow-rate variation from 0 to 1000 cu cm/min. The output of the sensor can be calibrated to provide a measurement of volume flow rate, pressure differential across channel ports, or mass flow rate. High sensitivity, wide dynamic range, and direct digital output are among the attractive features of this sensor. Theoretical expressions for the sensitivity and response time of the sensor are derived. It is shown that by using ultrasonic Lamb waves propagating in thin membranes, a flow sensor with faster response than a SAW sensor can be realized.

  20. The Parray as an Acoustic Sensor.

    DTIC Science & Technology

    1980-07-07

    AD-A87 071 TEXAS UV Al AUSTIN APPLIED RESEARCH LABS F/B 17/1 HE PARRAY S N ACOUSTIC SENSOR.IU JUL 80 T B GOLOSBERRY N00039-78-C 0209 UNCLASSIFIED...ARLTRSDW CPY s THE PARRAY M* lACOUSIC SENSOR TOMMY G. Gotdv APPLIED RESEARCH_ LABORATORIES Pmopme x~mAUST. TEXA Wig - APPROVED FOR PUBLIC RELEASE...DEPARTMENT OF THE NAVY WASHINGTON, DC 2M0 La -I2 - I , " " .C ’ THE PARRAY AS AN ACOUSTIC SENSOR • J by Tommy G i Goldsberry APPLIED RESEAkRCH

  1. Wireless Multiplexed Surface Acoustic Wave Sensors Project

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.

    2014-01-01

    Wireless Surface Acoustic Wave (SAW) Sensor is a new technology for obtaining multiple, real-time measurements under extreme environmental conditions. This project plans to develop a wireless multiplexed sensor system that uses SAW sensors, with no batteries or semiconductors, that are passive and rugged, can operate down to cryogenic temperatures and up to hundreds of degrees C, and can be used to sense a wide variety of parameters over reasonable distances (meters).

  2. Acoustic sensors using microstructures tunable with energy other than acoustic energy

    DOEpatents

    Datskos, Panagiotis G.

    2003-11-25

    A sensor for detecting acoustic energy includes a microstructure tuned to a predetermined acoustic frequency and a device for detecting movement of the microstructure. A display device is operatively linked to the movement detecting device. When acoustic energy strikes the acoustic sensor, acoustic energy having a predetermined frequency moves the microstructure, where the movement is detected by the movement detecting device.

  3. Acoustic sensors using microstructures tunable with energy other than acoustic energy

    DOEpatents

    Datskos, Panagiotis G.

    2005-06-07

    A sensor for detecting acoustic energy includes a microstructure tuned to a predetermined acoustic frequency and a device for detecting movement of the microstructure. A display device is operatively linked to the movement detecting device. When acoustic energy strikes the acoustic sensor, acoustic energy having a predetermined frequency moves the microstructure, where the movement is detected by the movement detecting device.

  4. Multipurpose Acoustic Sensor for Downhole Fluid Monitoring

    SciTech Connect

    Pantea, Cristian

    2012-05-04

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

  5. Surface acoustic wave vapor sensors based on resonator devices

    NASA Astrophysics Data System (ADS)

    Grate, Jay W.; Klusty, Mark

    1991-05-01

    Surface acoustic wave (SAW) devices fabricated in the resonator configuration have been used as organic vapor sensors and compared with delay line devices more commonly used. The experimentally determined mass sensitivities of 200, 300, and 400 MHz resonators and 158 MHz delay lines coated with Langmuir-Blodgett films of poly(vinyl tetradecanal) are in excellent agreement with theoretical predictions. The response of LB- and spray-coated sensors to various organic vapors were determined, and scaling laws for mass sensitivities, vapor sensitivities, and detection limits are discussed. The 200 MHz resonators provide the lowest noise levels and detection limits of all the devices examined.

  6. Acoustic Sensor for Voice with Embedded Physiology

    DTIC Science & Technology

    1999-01-01

    1.0 BACKGROUND ARL has developed a new method to measure human physiology and monitor health and performance parameters. This consists of an...conforms to the human body, and enhances the signal-to-noise-ratio (SNR) of human physiology to that of ambient noise. An acoustic sensor of this type

  7. Acoustic sensor networks for woodpecker localization

    NASA Astrophysics Data System (ADS)

    Wang, H.; Chen, C. E.; Ali, A.; Asgari, S.; Hudson, R. E.; Yao, K.; Estrin, D.; Taylor, C.

    2005-08-01

    Sensor network technology can revolutionize the study of animal ecology by providing a means of non-intrusive, simultaneous monitoring of interaction among multiple animals. In this paper, we investigate design, analysis, and testing of acoustic arrays for localizing acorn woodpeckers using their vocalizations. Each acoustic array consists of four microphones arranged in a square. All four audio channels within the same acoustic array are finely synchronized within a few micro seconds. We apply the approximate maximum likelihood (AML) method to synchronized audio channels of each acoustic array for estimating the direction-of-arrival (DOA) of woodpecker vocalizations. The woodpecker location is estimated by applying least square (LS) methods to DOA bearing crossings of multiple acoustic arrays. We have revealed the critical relation between microphone spacing of acoustic arrays and robustness of beamforming of woodpecker vocalizations. Woodpecker localization experiments using robust array element spacing in different types of environments are conducted and compared. Practical issues about calibration of acoustic array orientation are also discussed.

  8. Surface acoustic wave oxygen sensor

    NASA Technical Reports Server (NTRS)

    Collman, James P.; Oglesby, Donald M.; Upchurch, Billy T.; Leighty, Bradley D.; Zhang, Xumu; Herrmann, Paul C.

    1994-01-01

    A surface acoustic wave (SAW) device that responds to oxygen pressure was developed by coating a 158 MHz quartz surface acoustic wave (SAW) device with an oxygen binding agent. Two types of coatings were used. One type was prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer containing the axial ligand. A second type was prepared with an oxygen binding porphyrin solution containing excess axial ligand without a polymer matrix. In the polymer based coatings, the copolymer served to provide the axial ligand to the oxygen binding agent and as a coating matrix on the surface of the SAW device. The oxygen sensing SAW device has been shown to bind oxygen following a Langmuir isotherm and may be used to measure the equilibrium constant of the oxygen binding compound in the coating matrix.

  9. Fiber based photonic-crystal acoustic sensor

    NASA Astrophysics Data System (ADS)

    Kilic, Onur

    Photonic-crystal slabs are two-dimensional photonic crystals etched into a dielectric layer such as silicon. Standard micro fabrication techniques can be employed to manufacture these structures, which makes it feasible to produce them in large areas, usually an important criterion for practical applications. An appealing feature of these structures is that they can be employed as free-space optical devices such as broadband reflectors. The small thickness of the slab (usually in the vicinity of half a micron) also makes it deflectable. These combined optical and mechanical properties make it possible to employ photonic-crystal slabs in a range of practical applications, including displacement sensors, which in turn can be used for example to detect acoustic waves. An additional benefit of employing a photonic-crystal slab is that it is possible to tailor its optical and mechanical properties by adjusting the geometrical parameters of the structure such as hole radius or shape, pitch, and the slab thickness. By altering the hole radius and pitch, it is possible to make broadband reflectors or sharp transmission filters out of these structures. Adjusting the thickness also affects its deformability, making it possible to make broadband mirrors compliant to acoustic waves. Altering the hole shape, for example by introducing an asymmetry, extends the functionalities of photonic-crystal slabs even further. Breaking the symmetry by introducing asymmetric holes enables polarization-sensitive devices such as retarders, polarization beam splitters, and photonic crystals with additional non-degenerate resonances useful for increased sensitivity in sensors. All these practical advantages of photonic-crystal slabs makes them suitable as key components in micromachined sensor applications. We report one such example of an application of photonic-crystal slabs in the form of a micromachined acoustic sensor. It consists of a Fabry-Perot interferometer made of a photonic

  10. Surface acoustic wave (SAW) vibration sensors.

    PubMed

    Filipiak, Jerzy; Solarz, Lech; Steczko, Grzegorz

    2011-01-01

    In the paper a feasibility study on the use of surface acoustic wave (SAW) vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit.

  11. Study of piezo based sensors for acoustic particle detection

    NASA Astrophysics Data System (ADS)

    Anton, G.; Graf, K.; Hößl, J.; Kappes, A.; Karg, T.; Katz, U.; Kretschmer, W.; Kuch, S.; Lahmann, R.; Naumann, C.; Salomon, K.

    2006-11-01

    We present a characterisation of piezo sensors for acoustic particle detection. Electrical impedance, mechanical displacement and the sensitivity of piezo sensors were measured and modelled using a simple equivalent circuit diagram. In addition, finite element simulations were performed to describe the behaviour of the sensors. Their application for acoustic particle detection is discussed.

  12. Multiple-frequency surface acoustic wave devices as sensors

    NASA Astrophysics Data System (ADS)

    Ricco, Antonio J.; Martin, Stephen J.

    We have designed, fabricated, and tested a multiple-frequency acoustic wave (MUFAW) device on ST-cut quartz with nominal surface acoustic wave (SAW) center frequencies of 16, 40, 100, and 250 MHz. The four frequencies are obtained by patterning four sets of input and output interdigital transducers of differing periodicities on a single substrate. Such a device allows the frequency dependence of AW sensor perturbations to be examined, aiding in the elucidation of the operative interaction mechanism(s). Initial measurements of the SAW response to the vacuum deposition of a thin nickel film show the expected frequency dependence of mass sensitivity in addition to the expected frequency independence of the magnitude of the acoustoelectric effect. By measuring changes in both wave velocity and attenuation at multiple frequencies, extrinsic perturbations such as temperature and pressure changes are readily differentiated from one another and from changes in surface mass.

  13. Individually Identifiable Surface Acoustic Wave Sensors, Tags and Systems

    NASA Technical Reports Server (NTRS)

    Hines, Jacqueline H. (Inventor); Solie, Leland P. (Inventor); Tucker, Dana Y. G. (Inventor); Hines, Andrew T. (Inventor)

    2017-01-01

    A surface-launched acoustic wave sensor tag system for remotely sensing and/or providing identification information using sets of surface acoustic wave (SAW) sensor tag devices is characterized by acoustic wave device embodiments that include coding and other diversity techniques to produce groups of sensors that interact minimally, reducing or alleviating code collision problems typical of prior art coded SAW sensors and tags, and specific device embodiments of said coded SAW sensor tags and systems. These sensor/tag devices operate in a system which consists of one or more uniquely identifiable sensor/tag devices and a wireless interrogator. The sensor device incorporates an antenna for receiving incident RF energy and re-radiating the tag identification information and the sensor measured parameter(s). Since there is no power source in or connected to the sensor, it is a passive sensor. The device is wirelessly interrogated by the interrogator.

  14. Love wave acoustic sensor for testing in liquids

    NASA Astrophysics Data System (ADS)

    Pan, Haifeng; Zhu, Huizhong; Feng, Guanping

    2001-09-01

    Love wave is one type of the surface acoustic waves (SAWs). It is guided acoustic mode propagating in ta thin layer deposited on a substrate. Because of its advantages of high mass sensitivity, low noise level and being fit for operating in liquids, Love wave acoustic sensors have become one of the hot spots in the research of biosensor nowadays. In this paper the Love wave devices with the substrate of ST-cut quartz and the guiding layers of PMMA and fused quartz were fabricated successfully. By measuring the transfer function S21 and the insertion loss of the devices, the characteristics of the Rayleigh wave device and the Love wave devices with different guiding layers in gas phase and liquid phase were compared. It was validated that the Love wave sensor is suitable for testing in liquids but the Rayleigh wave sensor is not. What's more, SiO2 is the more proper material for the guiding layer of the Love wave device.

  15. Surface acoustic wave gas sensor based on film conductivity changes

    NASA Astrophysics Data System (ADS)

    Ricco, A. J.; Martin, S. J.; Zipperian, T. E.

    1985-12-01

    The first surfce acoustic wave (SAW) sensor that functions via changes in conductivity of a thin surface film is reported. A lead phthalocyanine (PbPc) thin film is deposted on the acoustic progagation path of a LiNbO3 SAW delay line, which serves as the feedback element of an oscillator circuit. Reaction with strongly oxidizing gases, in particular NO2, increases the conductivity of the PbPc film. Acoustoelectric coupling of the traveling electric potential wave associated with the SAW-to-charge carriers in the PbPc film slows the acoustic wave velocity, altering the oscillation frequency of the circuit. This sensor is about 1000 times more sensitive, in terms of the number of NO2 molecules that can be detected (10 to the 16th molecules/cu cm of PbPc film), than an identical SAW sensor functioning via mass loading would be. Sensitivity to a few ppm of NO2 in N2 has been demonstrated.

  16. Surface acoustic wave gas sensor based on film conductivity changes

    NASA Astrophysics Data System (ADS)

    Ricco, A. J.; Martin, S. J.; Zipperian, T. E.

    The first surface acoustic wave (SAW) sensor that functions via changes in conductivity of a thin surface film is reported. A lead phthalocyanine (PbPc) thin film is deposited on the acoustic propagation path of a LiNbO3 SAW delay line, which serves as the feedback element of an oscillator circuit. Reaction with strongly oxidizing gases, in particular NO2, increases the conductivity of the PbPc film. Acoustoelectic coupling of the traveling electric potential wave associated with the SAW-to-charge carriers in the PbPc film slows the acoustic wave velocity, altering the oscillation frequency of the circuit. This sensor is about 1000 times more sensitive, in terms of the number of NO2 molecules that can be detected (10 to the 16th molecules/cu cm of PbPc film), than an identical SAW sensor functioning via mass loading would be. Sensitivity to a few ppm of NO2 in Ne was demonstrated.

  17. Acoustic and Seismic Modalities for Unattended Ground Sensors

    SciTech Connect

    Elbring, G.J.; Ladd, M.D.; McDonald, T.S.; Sleefe, G.E.

    1999-03-31

    In this paper, we have presented the relative advantages and complementary aspects of acoustic and seismic ground sensors. A detailed description of both acoustic and seismic ground sensing methods has been provided. Acoustic and seismic phenomenology including source mechanisms, propagation paths, attenuation, and sensing have been discussed in detail. The effects of seismo-acoustic and acousto-seismic interactions as well as recommendations for minimizing seismic/acoustic cross talk have been highlighted. We have shown representative acoustic and seismic ground sensor data to illustrate the advantages and complementary aspects of the two modalities. The data illustrate that seismic transducers often respond to acoustic excitation through acousto-seismic coupling. Based on these results, we discussed the implications of this phenomenology on the detection, identification, and localization objectives of unattended ground sensors. We have concluded with a methodology for selecting the preferred modality (acoustic and/or seismic) for a particular application.

  18. Surface acoustic wave devices for sensor applications

    NASA Astrophysics Data System (ADS)

    Bo, Liu; Xiao, Chen; Hualin, Cai; Mohammad, Mohammad Ali; Xiangguang, Tian; Luqi, Tao; Yi, Yang; Tianling, Ren

    2016-02-01

    Surface acoustic wave (SAW) devices have been widely used in different fields and will continue to be of great importance in the foreseeable future. These devices are compact, cost efficient, easy to fabricate, and have a high performance, among other advantages. SAW devices can work as filters, signal processing units, sensors and actuators. They can even work without batteries and operate under harsh environments. In this review, the operating principles of SAW sensors, including temperature sensors, pressure sensors, humidity sensors and biosensors, will be discussed. Several examples and related issues will be presented. Technological trends and future developments will also be discussed. Project supported by the National Natural Science Foundation of China (Nos. 60936002, 61025021, 61434001, 61574083), the State Key Development Program for Basic Research of China (No. 2015CB352100), the National Key Project of Science and Technology (No. 2011ZX02403-002) and the Special Fund for Agroscientific Research in the Public Interest of China (No. 201303107). M.A.M is additionally supported by the Postdoctoral Fellowship (PDF) program of the Natural Sciences and Engineering Research Council (NSERC) of Canada and the China Postdoctoral Science Foundation (CPSF).

  19. Cooperative implementation of a high temperature acoustic sensor

    NASA Technical Reports Server (NTRS)

    Baldini, S. E.; Nowakowski, Edward; Smith, Herbert G.; Friebele, E. J.; Putnam, Martin A.; Rogowski, Robert; Melvin, Leland D.; Claus, Richard O.; Tran, Tuan; Holben, Milford S., Jr.

    1991-01-01

    The current status and results of a cooperative program aimed at the implementation of a high-temperature acoustic/strain sensor onto metallic structures are reported. The sensor systems that are to be implemented under this program will measure thermal expansion, maneuver loads, aircraft buffet, sonic fatigue, and acoustic emissions in environments that approach 1800 F. The discussion covers fiber development, fabrication of an extrinsic Fabry-Perot interferometer acoustic sensor, sensor mounting/integration, and results of an evaluation of the sensor capabilities.

  20. Development of a MEMS acoustic emission sensor system

    NASA Astrophysics Data System (ADS)

    Greve, David W.; Oppenheim, Irving J.; Wu, Wei; Wright, Amelia P.

    2007-04-01

    and the second mode frequency, strongly approximating the desirable rigid plate limit. The effect is modeled analytically and is verified experimentally by measurement of the resonance frequencies in the new transducers. Another improvement arises from the use of a pin grid array ceramic package, in which the MEMS chip is acoustically coupled to the structure with only two interfaces, through a ceramic medium that is negligible in thickness when compared to wavelengths of interest. Like other acoustic emission sensors, those on the 2006 MEMS chip are sensitive only to displacements normal to the surface on which the device is mounted. To overcome that long-standing limitation, a new MEMS sensor sensitive to in-plane motion has been designed, featuring a different spring-mass mechanism and creating the signal by the change in capacitance between stationary and moving fingers. Predicted damping is much lower for the case of the in-plane sensor, and squeeze-film damping is used selectively to isolate the desired in-plane mechanical response from any unwanted out-of-plane response. The new spring-mass mechanism satisfies the design rules for the PolyMUMPS fabrication (foundry) process. A 3-D MEMS sensor system is presently being fabricated, collocating two in-plane sensors and one out-of-plane sensor at the mm scale, which is very short compared to the acoustic wavelength of interest for stress waves created by acoustic emission events.

  1. Measuring aeolian sand transport using acoustic sensors

    NASA Astrophysics Data System (ADS)

    Poortinga, Ate; van Rheenen, Hans; Ellis, Jean T.; Sherman, Douglas J.

    2015-03-01

    Acoustic sensors are frequently used to measure aeolian saltation. Different approaches are used to process the signals from these instruments. The goal of this paper is to describe and discuss a method to measure aeolian saltation with acoustic sensors. In a laboratory experiment, we measured the output from an advanced signal processing scheme on the circuit board of the saltiphone. We use a software implementation of this processing scheme to re-analyse data from four miniphones obtained during a field experiment. It is shown that a set of filters remove background noise outside the frequency spectrum of aeolian saltation (at 8 kHz), whereas signals within this frequency spectrum are amplified. The resulting analogue signal is a proxy of the energy. Using an AC pulse convertor, this signal can be converted into a digital and analogue count signal or an analogue energy signal, using a rectifier and integrator. Spatio-temporal correlation between field deployed miniphones increases by using longer integration times for signal processing. To quantify aeolian grain impact, it is suggested to use the analogue energy output, as this mode is able to detect changes in frequency and amplitude. The analogue and digital count signals are able to detect an increase in frequency, but are not able to detect an increase in signal amplitude. We propose a two-stage calibration scheme consisting of (1) a factory calibration, to set the frequency spectrum of the sensor and (2) a standardized drop-test conducted before and after the experiment to evaluate the response of the sensor.

  2. Broadband Field Directionally Mapping using Maneuverable Acoustic Sensor Arrays

    DTIC Science & Technology

    2015-09-30

    Maneuverable Acoustic Sensor Arrays David Smith Dept. of Electrical and Computer Engineering Duke University, Box 90291 Durham, NC 27708 phone: (919) 660... acoustic arrays to resolve targets from interferers, and 2) improve the target detection, localization, and tracking performance of long arrays during tow...splines) EM algorithm. Both algorithms were run using a simulated 30 element acoustic vector sensor array with 900 snapshots. Attention has also

  3. Magnetic nanowires for acoustic sensors (invited)

    NASA Astrophysics Data System (ADS)

    McGary, Patrick D.; Tan, Liwen; Zou, Jia; Stadler, Bethanie J. H.; Downey, Patrick R.; Flatau, Alison B.

    2006-04-01

    Tiny hairlike sensors or cilia play a very important role in detection for many biological species, including humans. This research took inspiration from the packaging and transduction processes of the inner ear's cochlea and cilia to design acoustic sensors. Specifically, this work uses nanowires of magnetostrictive materials as artificial cilia to sense acoustic signals. Anodic aluminum oxide (AAO) templates with hexagonal spacings were fabricated using a two-step anodization process as well as nanoimprint assisted self-assembly and were characterized using atomic force microscopy. Patterned microelectrodes were also fabricated at the backside of several templates using photolithography. Ni, Co, and Galfenol (Fe1-xGax0.1<=x<=0.25 at. %) nanowires were fabricated using electrochemical deposition into nanoporous AAO templates where the pores had various geometries and some had large-area ordering as dictated by nanoimprinting. High aspect ratio nanowires with diameters varying from 10 to 200 nm and lengths up to 60 μm were fabricated in arrays and were collectively and individually characterized using scanning electron microscopy. Galfenol thin films, fabricated electrochemically using a Hull cell, were characterized using x-ray diffraction and energy dispersive x-ray spectroscopy to determine the optimum current density for deposition. The magnetic response of millimeter-scale cantilevered beams to dynamic bending loads was also measured and compared to constitutive and free-energy models. A giant magnetoresistive sensor behind the beam measured the magnetic response of mechanical excitation applied to the tip of each rod and validated the models. Potenial applications of these nanowire cilia include sonar arrays, underwater cameras, and medical devices.

  4. Estimating propagation velocity through a surface acoustic wave sensor

    DOEpatents

    Xu, Wenyuan; Huizinga, John S.

    2010-03-16

    Techniques are described for estimating the propagation velocity through a surface acoustic wave sensor. In particular, techniques which measure and exploit a proper segment of phase frequency response of the surface acoustic wave sensor are described for use as a basis of bacterial detection by the sensor. As described, use of velocity estimation based on a proper segment of phase frequency response has advantages over conventional techniques that use phase shift as the basis for detection.

  5. Method and apparatus for measuring surface changes, in porous materials, using multiple differently-configured acoustic sensors

    DOEpatents

    Hietala, Susan Leslie; Hietala, Vincent Mark; Tigges, Chris Phillip

    2001-01-01

    A method and apparatus for measuring surface changes, such as mass uptake at various pressures, in a thin-film material, in particular porous membranes, using multiple differently-configured acoustic sensors.

  6. Tracking Moving Acoustic Sources With a Network of Sensors

    DTIC Science & Technology

    2002-10-01

    Tracking Moving Acoustic Sources With a Network of Sensors by Richard J. Kozick and Brian M. Sadler ARL-TR-2750 October 2002 Approved for public...October 2002 Tracking Moving Acoustic Sources With a Network of Sensors Richard J. Kozick Bucknell University, Electrical Engineering Department Brian M...Model for a Nonmoving Source 4 2.1 Cramér-Rao Bound (CRB) . . . . . . . . . . . . . . . . . . . . 6 2.2 Examples

  7. Fiber optic acoustic emission sensors for harsh environment health monitoring

    NASA Astrophysics Data System (ADS)

    Borinski, Jason W.; Duke, John C., Jr.; Horne, Michael R.

    2001-07-01

    Optical fiber sensors are rapidly emerging as viable alternatives to piezoelectric devices as effective means of detecting and quantifying acoustic emission (AE). Compared to traditional piezoelectric-based sensors, optical fiber sensors offer much smaller size, reduced weight, ability to operate at temperatures up to 2000 degree(s)C, immunity to electromagnetic interference, resistance to corrosive environments, inherent safety within flammable environments, and the ability to multiplex multiple sensors on a single fiber. The authors have investigated low-profile fiber optic-based AE sensors for non-destructive evaluation (NDE) systems. In particular, broadband and resonant type optical fiber sensors were developed for monitoring acoustic emission for NDE of pressurized composite vessels and commercial airframe structures. The authors developed an in-plane, broadband sensor design based on optical strain gage technology. In addition, an out-of-plane, resonant sensor was developed using micromachining techniques. The sensors have been evaluated for performance using swept frequency and impulse excitation techniques and compared to conventional piezoelectric transducers. Further, application experiments were conducted using these sensors on both aluminum lap-joints and composite fracture coupons, with collocated piezoelectric transducers. The results indicate that optical fiber AE sensors can be used as transducers sensitive to acoustic events and the indication of imminent failure of a structure, making these sensors useful in many applications where conventional piezoelectric transducers are not well suited.

  8. Acoustic Sensor Design for Dark Matter Bubble Chamber Detectors.

    PubMed

    Felis, Ivan; Martínez-Mora, Juan Antonio; Ardid, Miguel

    2016-06-10

    Dark matter bubble chamber detectors use piezoelectric sensors in order to detect and discriminate the acoustic signals emitted by the bubbles grown within the superheated fluid from a nuclear recoil produced by a particle interaction. These sensors are attached to the outside walls of the vessel containing the fluid. The acoustic discrimination depends strongly on the properties of the sensor attached to the outer wall of the vessel that has to meet the requirements of radiopurity and size. With the aim of optimizing the sensor system, a test bench for the characterization of the sensors has been developed. The sensor response for different piezoelectric materials, geometries, matching layers, and backing layers have been measured and contrasted with FEM simulations and analytical models. The results of these studies lead us to have a design criterion for the construction of specific sensors for the next generation of dark matter bubble chamber detectors (250 L).

  9. Acoustic Sensor Design for Dark Matter Bubble Chamber Detectors

    PubMed Central

    Felis, Ivan; Martínez-Mora, Juan Antonio; Ardid, Miguel

    2016-01-01

    Dark matter bubble chamber detectors use piezoelectric sensors in order to detect and discriminate the acoustic signals emitted by the bubbles grown within the superheated fluid from a nuclear recoil produced by a particle interaction. These sensors are attached to the outside walls of the vessel containing the fluid. The acoustic discrimination depends strongly on the properties of the sensor attached to the outer wall of the vessel that has to meet the requirements of radiopurity and size. With the aim of optimizing the sensor system, a test bench for the characterization of the sensors has been developed. The sensor response for different piezoelectric materials, geometries, matching layers, and backing layers have been measured and contrasted with FEM simulations and analytical models. The results of these studies lead us to have a design criterion for the construction of specific sensors for the next generation of dark matter bubble chamber detectors (250 L). PMID:27294937

  10. 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.

  11. 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).

  12. Mass Load Distribution Dependence of Mass Sensitivity of Magnetoelastic Sensors under Different Resonance Modes

    PubMed Central

    Zhang, Kewei; Zhang, Lin; Chai, Yuesheng

    2015-01-01

    Magnetoelastic sensors as an important type of acoustic wave sensors have shown great promise for a variety of applications. Mass sensitivity is a key parameter to characterize its performance. In this work, the effects of mass load distribution on the mass sensitivity of a magnetoelastic sensor under different resonance modes were theoretically investigated using the modal analysis method. The results show that the mass sensitivity and “nodal point” positions are related to the point displacement, which is determined by the motion patterns. The motion patterns are affected by resonance modes and mass load distribution. Asymmetrical mass load distribution causes the motion patterns lose symmetry and leads to the shift of “nodal point”. The mass sensitivity changing with mass load distribution behaves like a sine wave with decaying amplitude and the minimum mass sensitivity appears at the first valley. This study provides certain theoretical guidance for optimizing the mass sensitivity of a magnetoelastic sensor or other acoustic wave based sensors. PMID:26295233

  13. On Modeling Eavesdropping Attacks in Underwater Acoustic Sensor Networks †

    PubMed Central

    Wang, Qiu; Dai, Hong-Ning; Li, Xuran; Wang, Hao; Xiao, Hong

    2016-01-01

    The security and privacy of underwater acoustic sensor networks has received extensive attention recently due to the proliferation of underwater activities. This paper proposes an analytical model to investigate the eavesdropping attacks in underwater acoustic sensor networks. Our analytical framework considers the impacts of various underwater acoustic channel conditions (such as the acoustic signal frequency, spreading factor and wind speed) and different hydrophones (isotropic hydrophones and array hydrophones) in terms of network nodes and eavesdroppers. We also conduct extensive simulations to evaluate the effectiveness and the accuracy of our proposed model. Empirical results show that our proposed model is quite accurate. In addition, our results also imply that the eavesdropping probability heavily depends on both the underwater acoustic channel conditions and the features of hydrophones. PMID:27213379

  14. On Modeling Eavesdropping Attacks in Underwater Acoustic Sensor Networks.

    PubMed

    Wang, Qiu; Dai, Hong-Ning; Li, Xuran; Wang, Hao; Xiao, Hong

    2016-05-18

    The security and privacy of underwater acoustic sensor networks has received extensive attention recently due to the proliferation of underwater activities. This paper proposes an analytical model to investigate the eavesdropping attacks in underwater acoustic sensor networks. Our analytical framework considers the impacts of various underwater acoustic channel conditions (such as the acoustic signal frequency, spreading factor and wind speed) and different hydrophones (isotropic hydrophones and array hydrophones) in terms of network nodes and eavesdroppers. We also conduct extensive simulations to evaluate the effectiveness and the accuracy of our proposed model. Empirical results show that our proposed model is quite accurate. In addition, our results also imply that the eavesdropping probability heavily depends on both the underwater acoustic channel conditions and the features of hydrophones.

  15. Fiber-optic interferometric acoustic sensors for wind tunnel applications

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.

    1993-01-01

    Progress in developing fiber-optic interferometric sensors for aeroacoustic measurements in wind tunnels, performed under the NASA program, is reported. Preliminary results show that the fiber-optic interferometer sensor array is a powerful instrument for solving complex acoustic measurement problems in wind tunnels, which cannot be resolved with the conventional transducer technique.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  17. Modeling of a Surface Acoustic Wave Strain Sensor

    NASA Technical Reports Server (NTRS)

    Wilson, W. C.; Atkinson, Gary M.

    2010-01-01

    NASA Langley Research Center is investigating Surface Acoustic Wave (SAW) sensor technology for harsh environments aimed at aerospace applications. To aid in development of sensors a model of a SAW strain sensor has been developed. The new model extends the modified matrix method to include the response of Orthogonal Frequency Coded (OFC) reflectors and the response of SAW devices to strain. These results show that the model accurately captures the strain response of a SAW sensor on a Langasite substrate. The results of the model of a SAW Strain Sensor on Langasite are presented

  18. Biomimetic smart sensors for autonomous robotic behavior I: acoustic processing

    NASA Astrophysics Data System (ADS)

    Deligeorges, Socrates; Xue, Shuwan; Soloway, Aaron; Lichtenstein, Lee; Gore, Tyler; Hubbard, Allyn

    2009-05-01

    Robotics are rapidly becoming an integral tool on the battlefield and in homeland security, replacing humans in hazardous conditions. To enhance the effectiveness of robotic assets and their interaction with human operators, smart sensors are required to give more autonomous function to robotic platforms. Biologically inspired sensors are an essential part of this development of autonomous behavior and can increase both capability and performance of robotic systems. Smart, biologically inspired acoustic sensors have the potential to extend autonomous capabilities of robotic platforms to include sniper detection, vehicle tracking, personnel detection, and general acoustic monitoring. The key to enabling these capabilities is biomimetic acoustic processing using a time domain processing method based on the neural structures of the mammalian auditory system. These biologically inspired algorithms replicate the extremely adaptive processing of the auditory system yielding high sensitivity over broad dynamic range. The algorithms provide tremendous robustness in noisy and echoic spaces; properties necessary for autonomous function in real world acoustic environments. These biomimetic acoustic algorithms also provide highly accurate localization of both persistent and transient sounds over a wide frequency range, using baselines on the order of only inches. A specialized smart sensor has been developed to interface with an iRobot Packbot® platform specifically to enhance its autonomous behaviors in response to personnel and gunfire. The low power, highly parallel biomimetic processor, in conjunction with a biomimetic vestibular system (discussed in the companion paper), has shown the system's autonomous response to gunfire in complicated acoustic environments to be highly effective.

  19. Acoustic sensors in the helmet detect voice and physiology

    NASA Astrophysics Data System (ADS)

    Scanlon, Michael V.

    2003-09-01

    The Army Research Laboratory has developed body-contacting acoustic sensors that detect diverse physiological sounds such as heartbeats and breaths, high quality speech, and activity. These sensors use an acoustic impedance-matching gel contained in a soft, compliant pad to enhance the body borne sounds, yet significantly repel airborne noises due to an acoustic impedance mismatch. The signals from such a sensor can be used as a microphone with embedded physiology, or a dedicated digital signal processor can process packetized data to separate physiological parameters from voice, and log parameter trends for performance surveillance. Acoustic sensors were placed inside soldier helmets to monitor voice, physiology, activity, and situational awareness clues such as bullet shockwaves from sniper activity and explosions. The sensors were also incorporated into firefighter breathing masks, neck and wrist straps, and other protective equipment. Heart rate, breath rate, blood pressure, voice and activity can be derived from these sensors (reports at www.arl.army.mil/acoustics). Having numerous sensors at various locations provides a means for array processing to reduce motion artifacts, calculate pulse transit time for passive blood pressure measurement, and the origin of blunt/penetrating traumas such as ballistic wounding. These types of sensors give us the ability to monitor soldiers and civilian emergency first-responders in demanding environments, and provide vital signs information to assess their health status and how that person is interacting with the environment and mission at hand. The Objective Force Warrior, Scorpion, Land Warrior, Warrior Medic, and other military and civilian programs can potentially benefit from these sensors.

  20. End tidal carbon dioxide measurement using an electro acoustic sensor.

    PubMed

    Folke, M; Hok, B; Ekstrom, M; Backlund, Y

    2004-01-01

    End tidal carbon dioxide measurement with an electro-acoustic sensor is demonstrated. The sensor consists of an acoustic resonator coupled to a low cost electro-acoustic element. By simultaneous measurements with a reference sensor, the new device was tested on subjects performing exercise, hypo- and hyperventilation whereby the CO2concentration ranged from 2.1 to 7.0 kPa. The output from the experimental device correlated well with the reference CO2readings with a correlation coefficient of 0.976. Response time for expiration less than 0.8 seconds was noted. The new device could be useful in situations where selectivity to other gases is not important.

  1. Mass Spectrometry of Acoustically Levitated Droplets

    PubMed Central

    Westphall, Michael S.; Jorabchi, Kaveh; Smith, Lloyd M.

    2008-01-01

    Containerless sample handling techniques such as acoustic levitation offer potential advantages for mass spectrometry, by eliminating surfaces where undesired adsorption/desorption processes can occur. In addition, they provide a unique opportunity to study fundamental aspects of the ionization process as well as phenomena occurring at the air–droplet interface. Realizing these advantages is contingent, however, upon being able to effectively interface levitated droplets with a mass spectrometer, a challenging task that is addressed in this report. We have employed a newly developed charge and matrix-assisted laser desorption/ionization (CALDI) technique to obtain mass spectra from a 5-μL acoustically levitated droplet containing peptides and an ionic matrix. A four-ring electrostatic lens is used in conjunction with a corona needle to produce bursts of corona ions and to direct those ions toward the droplet, resulting in droplet charging. Analyte ions are produced from the droplet by a 337-nm laser pulse and detected by an atmospheric sampling mass spectrometer. The ion generation and extraction cycle is repeated at 20 Hz, the maximum operating frequency of the laser employed. It is shown in delayed ion extraction experiments that both positive and negative ions are produced, behavior similar to that observed for atmospheric pressure matrix-assisted laser absorption/ionization. No ion signal is observed in the absence of droplet charging. It is likely, although not yet proven, that the role of the droplet charging is to increase the strength of the electric field at the surface of the droplet, reducing chargere combination after ion desorption. PMID:18582090

  2. Sensitivity enhancement of fiber optic FBG sensor for acoustic emission

    NASA Astrophysics Data System (ADS)

    Seo, Dae-Cheol; Yoon, Dong-Jin; Kwon, Il-Bum; Lee, Seung-Suk

    2009-03-01

    A fiber optic Bragg grating based acoustic emission sensor system is developed to provide on-line monitoring of cracks or leaks in reactor vessel head penetration of nuclear power plants. Various type of fiber Bragg grating sensor including the variable length of sensing part was fabricated and prototype sensor system was tested by using PZT pulser and pencil lead break sources. In this study, we developed a cantilever type fiber sensor to enhance the sensitivity and to resonant frequency control. Two types of sensor attachment were used. First, the fiber Bragg grating sensor was fully bonded to the surface using bonding agent. Second one is that one part of fiber was partially bonded to surface and the other part of fiber will be remained freely. The resonant frequency of the fiber Bragg grating sensor will depend on the length of sensing part. Various kinds of resonant type fiber Bragg grating acoustic emission sensors were developed. Also several efforts were done to enhance the sensitivity of FBG AE sensor, which include FBG spectrum optimization and electrical and optical noise reduction. Finally, based on the self-developed acquisition system, a series of tests demonstrate the ability of the developed fiber sensor system to detect a pencil lead break event and continuous leak signal.

  3. Acoustic emission monitoring using a multimode optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Vandenplas, Steve; Papy, Jean-Michel; Wevers, Martine; Van Huffel, Sabine

    2004-07-01

    Permanent damage in various materials and constructions often causes high-energy high-frequency acoustic waves. To detect those so called `acoustic emission (AE) events', in most cases ultrasonic transducers are embedded in the structure or attached to its surface. However, for many applications where event localization is less important, an embedded low-cost multimode optical fiber sensor configured for event counting may be a better alternative due to its corrosion resistance, immunity to electromagnetic interference and light-weight. The sensing part of this intensity-modulated sensor consists of a multimode optical fiber. The sensing principle now relies on refractive index variations, microbending and mode-mode interferences by the action of the acoustic pressure wave. A photodiode is used to monitor the intensity of the optical signal and transient signal detection techniques (filtering, frame-to-frame analysis, recursive noise estimation, power detector estimator) on the photodiode output are applied to detect the events. In this work, the acoustic emission monitoring capabilities of the multimode optical fiber sensor are demonstrated with the fiber sensor embedded in the liner of a Power Data Transmission (PDT) coil to detect damage (delamination, matrix cracking and fiber breaking) while bending the coil. With the Hankel Total Least Square (HTLS) technique, it is shown that both the acoustic emission signal and optical signal can be modeled with a sum of exponentially damped complex sinusoids with common poles.

  4. Dual output acoustic wave sensor for molecular identification

    DOEpatents

    Frye, Gregory C.; Martin, Stephen J.

    1991-01-01

    A method of identification and quantification of absorbed chemical species by measuring changes in both the velocity and the attenuation of an acoustic wave traveling through a thin film into which the chemical species is sorbed. The dual output response provides two independent sensor responses from a single sensing device thereby providing twice as much information as a single output sensor. This dual output technique and analysis allows a single sensor to provide both the concentration and the identity of a chemical species or permits the number of sensors required for mixtures to be reduced by a factor of two.

  5. Acoustic mapping of ocean currents using networked distributed sensors.

    PubMed

    Huang, Chen-Fen; Yang, T C; Liu, Jin-Yuan; Schindall, Jeff

    2013-09-01

    Distributed underwater sensors are expected to provide oceanographic monitoring over large areas. As fabrication technology advances, low cost sensors will be available for many uses. The sensors communicate to each other and are networked using acoustic communications. This paper first studies the performance of such systems for current measurements using tomographic inversion approaches to compare with that of a conventional system which distributes the sensors on the periphery of the area of interest. It then proposes two simple signal processing methods for ocean current mapping (using distributed networked sensors) aimed at real-time in-buoy processing. Tomographic inversion generally requires solving a challenging high dimensional inverse problem, involving substantial computations. Given distributed sensors, currents can be constructed locally based on data from neighboring sensors. It is shown using simulated data that similar results are obtained using distributed processing as using conventional tomographic approaches. The advantage for distributed systems is that by increasing the number of nodes, one gains a much more improved performance. Furthermore, distributed systems use much less energy than a conventional tomographic system for the same area coverage. Experimental data from an acoustic communication and networking experiment are used to demonstrate the feasibility of acoustic current mapping.

  6. Optimizing surface acoustic wave sensors for trace chemical detection

    SciTech Connect

    Frye, G.C.; Kottenstette, R.J.; Heller, E.J.

    1997-06-01

    This paper describes several recent advances for fabricating coated surface acoustic wave (SAW) sensors for applications requiring trace chemical detection. Specifically, we have demonstrated that high surface area microporous oxides can provide 100-fold improvements in SAW sensor responses compared with more typical polymeric coatings. In addition, we fabricated GaAs SAW devices with frequencies up to 500 MHz to provide greater sensitivity and an ideal substrate for integration with high-frequency electronics.

  7. A wireless acoustic emission sensor remotely powered by light

    NASA Astrophysics Data System (ADS)

    Zahedi, F.; Huang, H.

    2014-03-01

    In this paper, wireless sensing of acoustic emission (AE) signals using a battery-free sensor node remotely powered by light is presented. The wireless sensor consists of a piezoelectric wafer active sensor (PWAS) for AE signal acquisition and a wireless transponder that performs signal conditioning, frequency conversion, and wireless transmission. For signal conditioning, a voltage follower that consumes less than 2 mW was introduced to buffer the high impedance of the PWAS from the low impedance of the wireless transponder. A photocell-based energy harvester with a stable voltage output was developed to power the voltage follower so that the wireless AE sensor can operate without an external power source. The principle of operation of the battery-free wireless AE sensor node and the sensor interrogation system is described, followed by a detailed description of the hardware implementation. The voltage follower and the wireless channel were characterized by ultrasound pitch-catch and pencil lead break experiments.

  8. Bio-Inspired Micromechanical Directional Acoustic Sensor

    NASA Astrophysics Data System (ADS)

    Swan, William; Alves, Fabio; Karunasiri, Gamani

    Conventional directional sound sensors employ an array of spatially separated microphones and the direction is determined using arrival times and amplitudes. In nature, insects such as the Ormia ochracea fly can determine the direction of sound using a hearing organ much smaller than the wavelength of sound it detects. The fly's eardrums are mechanically coupled, only separated by about 1 mm, and have remarkable directional sensitivity. A micromechanical sensor based on the fly's hearing system was designed and fabricated on a silicon on insulator (SOI) substrate using MEMS technology. The sensor consists of two 1 mm2 wings connected using a bridge and to the substrate using two torsional legs. The dimensions of the sensor and material stiffness determine the frequency response of the sensor. The vibration of the wings in response to incident sound at the bending resonance was measured using a laser vibrometer and found to be about 1 μm/Pa. The electronic response of the sensor to sound was measured using integrated comb finger capacitors and found to be about 25 V/Pa. The fabricated sensors showed good directional sensitivity. In this talk, the design, fabrication and characteristics of the directional sound sensor will be described. Supported by ONR and TDSI.

  9. Miniature fiber acoustic sensors using a photonic-crystal membrane

    NASA Astrophysics Data System (ADS)

    Jo, Wonuk; Akkaya, Onur C.; Solgaard, Olav; Digonnet, Michel J. F.

    2013-12-01

    This paper discusses recent developments in fiber acoustic sensors utilizing a miniature Fabry-Perot (FP) interferometer fabricated at the tip of a fiber. The FP is made of a high-reflectivity photonic-crystal membrane placed ˜30 μm from the reflective end of a single-mode fiber. When exposed to an acoustic wave the compliant membrane vibrates, and this vibration is detected as a modulation of the optical power reflected by the FP. The interferometer is enclosed in a sensor head designed, with the assistance of an electro-mechanical model, to minimize squeezed-film damping of the thin air gap between the reflectors and obtain a good acoustic response. The sensor head is fabricated out of silica elements and assembled with silicate bonding to minimize thermal expansion and ensure thermal stability. In the first sensor of this type the reflector at the fiber tip is a gold coating. It exhibits an average minimum detectable pressure (MDP) of 33 μPa/√Hz (1-30 kHz), a high thermal stability, and a weak polarization dependence. The second sensor incorporates several improvements, including a larger membrane for increased vibration amplitude, and higher reflectivity mirrors (PC and fiber tip) for increased displacement sensitivity. Its measured response is flat between ˜600 Hz and 20 kHz, with a normalized sensitivity as high as ˜0.17 Pa-1. Between 1 kHz and 30 kHz its average MDP is ˜2.6 μPa/√Hz, the lowest reported value for a fiber acoustic sensor this small. These results demonstrate the promising potential of this class of stable and compact optical sensors for highly sensitive detection in the audible range.

  10. High-frequency shear-horizontal surface acoustic wave sensor

    DOEpatents

    Branch, Darren W

    2013-05-07

    A Love wave sensor uses a single-phase unidirectional interdigital transducer (IDT) on a piezoelectric substrate for leaky surface acoustic wave generation. The IDT design minimizes propagation losses, bulk wave interferences, provides a highly linear phase response, and eliminates the need for impedance matching. As an example, a high frequency (.about.300-400 MHz) surface acoustic wave (SAW) transducer enables efficient excitation of shear-horizontal waves on 36.degree. Y-cut lithium tantalate (LTO) giving a highly linear phase response (2.8.degree. P-P). The sensor has the ability to detect at the pg/mm.sup.2 level and can perform multi-analyte detection in real-time. The sensor can be used for rapid autonomous detection of pathogenic microorganisms and bioagents by field deployable platforms.

  11. High-frequency shear-horizontal surface acoustic wave sensor

    DOEpatents

    Branch, Darren W

    2014-03-11

    A Love wave sensor uses a single-phase unidirectional interdigital transducer (IDT) on a piezoelectric substrate for leaky surface acoustic wave generation. The IDT design minimizes propagation losses, bulk wave interferences, provides a highly linear phase response, and eliminates the need for impedance matching. As an example, a high frequency (.about.300-400 MHz) surface acoustic wave (SAW) transducer enables efficient excitation of shear-horizontal waves on 36.degree. Y-cut lithium tantalate (LTO) giving a highly linear phase response (2.8.degree. P-P). The sensor has the ability to detect at the pg/mm.sup.2 level and can perform multi-analyte detection in real-time. The sensor can be used for rapid autonomous detection of pathogenic microorganisms and bioagents by field deployable platforms.

  12. Direction Finding Using Multiple MEMS Acoustic Sensors

    DTIC Science & Technology

    2015-09-01

    research is that it is possible to operate this microelectromechanical direction-finding sensor assembly to find the bearing of a signal on...sensor assembly to find the bearing of a signal on resonance over an angular range of 120° with a maximum uncertainty of 3.4°. vi THIS PAGE...documentation boasts an accuracy of plus or minus 7.5 degrees bearing accuracy within < 1 second with detection ranges greater than 400 m. Output is provided

  13. A Secure Communication Suite for Underwater Acoustic Sensor Networks

    PubMed Central

    Dini, Gianluca; Duca, Angelica Lo

    2012-01-01

    In this paper we describe a security suite for Underwater Acoustic Sensor Networks comprising both fixed and mobile nodes. The security suite is composed of a secure routing protocol and a set of cryptographic primitives aimed at protecting the confidentiality and the integrity of underwater communication while taking into account the unique characteristics and constraints of the acoustic channel. By means of experiments and simulations based on real data, we show that the suite is suitable for an underwater networking environment as it introduces limited, and sometimes negligible, communication and power consumption overhead. PMID:23202204

  14. Coded acoustic wave sensors and system using time diversity

    NASA Technical Reports Server (NTRS)

    Solie, Leland P. (Inventor); Hines, Jacqueline H. (Inventor)

    2012-01-01

    An apparatus and method for distinguishing between sensors that are to be wirelessly detected is provided. An interrogator device uses different, distinct time delays in the sensing signals when interrogating the sensors. The sensors are provided with different distinct pedestal delays. Sensors that have the same pedestal delay as the delay selected by the interrogator are detected by the interrogator whereas other sensors with different pedestal delays are not sensed. Multiple sensors with a given pedestal delay are provided with different codes so as to be distinguished from one another by the interrogator. The interrogator uses a signal that is transmitted to the sensor and returned by the sensor for combination and integration with the reference signal that has been processed by a function. The sensor may be a surface acoustic wave device having a differential impulse response with a power spectral density consisting of lobes. The power spectral density of the differential response is used to determine the value of the sensed parameter or parameters.

  15. An invisible acoustic sensor based on parity-time symmetry

    NASA Astrophysics Data System (ADS)

    Fleury, Romain; Sounas, Dimitrios; Alù, Andrea

    2015-01-01

    Sensing an incoming signal is typically associated with absorbing a portion of its energy, inherently perturbing the measurement and creating reflections and shadows. Here, in contrast, we demonstrate a non-invasive, shadow-free, invisible sensor for airborne sound waves at audible frequencies, which fully absorbs the impinging signal, without at the same time perturbing its own measurement or creating a shadow. This unique sensing device is based on the unusual scattering properties of a parity-time (PT) symmetric metamaterial device formed by a pair of electro-acoustic resonators loaded with suitably tailored non-Foster electrical circuits, constituting the acoustic equivalent of a coherent perfect absorber coupled to a coherent laser. Beyond the specific application to non-invasive sensing, our work broadly demonstrates the unique relevance of PT-symmetric metamaterials for acoustics, loss compensation and extraordinary wave manipulation.

  16. An invisible acoustic sensor based on parity-time symmetry.

    PubMed

    Fleury, Romain; Sounas, Dimitrios; Alù, Andrea

    2015-01-06

    Sensing an incoming signal is typically associated with absorbing a portion of its energy, inherently perturbing the measurement and creating reflections and shadows. Here, in contrast, we demonstrate a non-invasive, shadow-free, invisible sensor for airborne sound waves at audible frequencies, which fully absorbs the impinging signal, without at the same time perturbing its own measurement or creating a shadow. This unique sensing device is based on the unusual scattering properties of a parity-time (PT) symmetric metamaterial device formed by a pair of electro-acoustic resonators loaded with suitably tailored non-Foster electrical circuits, constituting the acoustic equivalent of a coherent perfect absorber coupled to a coherent laser. Beyond the specific application to non-invasive sensing, our work broadly demonstrates the unique relevance of PT-symmetric metamaterials for acoustics, loss compensation and extraordinary wave manipulation.

  17. Ultra-sensitive acoustic fiber sensors utilizing nano-membranes

    NASA Astrophysics Data System (ADS)

    Jo, Wonuk; Digonnet, M. J. F.

    2015-09-01

    A new, highly sensitive, compact fiber acoustic sensor is reported that implements a micro-fabricated silicon membrane with a π/2 phase step combined to a single-mode fiber to form a simple interferometric sensor head. Compared to high-sensitivity membrane-based fiber Fabry-Perot (FP) sensors, it has a similar pressure resolution, it operates over a much broad range of wavelengths (~+/-150 nm vs. ~+/-1 nm), and fabrication is simpler. A prototype is reported with an average minimum detectable pressure (MDP) as low as 5.4 μPa/√Hz (1-30 kHz), in agreement with a model. A state-of-the-art FP fiber sensor with an average MDP about twice as low is described for comparison.

  18. High-Temperature Piezoelectric Crystals for Acoustic Wave Sensor Applications.

    PubMed

    Zu, Hongfei; Wu, Huiyan; Wang, Qing-Ming

    2016-03-01

    In this review paper, nine different types of high-temperature piezoelectric crystals and their sensor applications are overviewed. The important materials' properties of these piezoelectric crystals including dielectric constant, elastic coefficients, piezoelectric coefficients, electromechanical coupling coefficients, and mechanical quality factor are discussed in detail. The determination methods of these physical properties are also presented. Moreover, the growth methods, structures, and properties of these piezoelectric crystals are summarized and compared. Of particular interest are langasite and oxyborate crystals, which exhibit no phase transitions prior to their melting points ∼ 1500 °C and possess high electrical resistivity, piezoelectric coefficients, and mechanical quality factor at ultrahigh temperature ( ∼ 1000 °C). Finally, some research results on surface acoustic wave (SAW) and bulk acoustic wave (BAW) sensors developed using this high-temperature piezoelectric crystals are discussed.

  19. Understanding Piezo Based Sensors for Acoustic Neutrino Detection

    NASA Astrophysics Data System (ADS)

    Naumann, C. L.; Anton, G.; Graf, K.; Höβl, J.; Kappes, A.; Katz, U. F.; Lahmann, R.; Salomon, K.

    2007-09-01

    The ANTARES collaboration is currently installing a neutrino telescope off the French Mediterranean coast to measure diffuse fluxes and point sources of high energy cosmic neutrinos. The complete detector will consist of 900 photomultipliers on 12 detector lines, using 0.01km3 of sea water as target material[1]. As part of the ANTARES deep-sea research infrastructure, the Erlangen group is planning to modify several ANTARES storeys by fitting them with acoustic receivers to study the feasibility of acoustic neutrino detection in the deep sea. In this paper, studies of the electromechanical properties of piezoelectric sensors are presented, based on an equivalent circuit diagram for the coupled mechanical and electrical oscillations of a piezoelectric element. A method for obtaining the system parameters as well as derivations of sensor properties like pressure sensitivity and intrinsic noise are treated and results compared to measurements. Finally, a possible application of these results for simulating system response and optimising reconstruction algorithms is discussed.

  20. A large fiber sensor network for an acoustic neutrino telescope

    NASA Astrophysics Data System (ADS)

    Buis, Ernst-Jan; Doppenberg, Ed; Lahmann, Robert; Toet, Peter

    2017-03-01

    The scientific prospects of detecting neutrinos with an energy close or even higher than the GKZ cut-off energy has been discussed extensively in literature. It is clear that due to their expected low flux, the detection of these ultra-high energy neutrinos (Ev > 1018 eV) requires a telescope larger than 100 km3. Acoustic detection may provide a way to observe these ultra-high energy cosmic neutrinos, as sound that they induce in the deep sea when neutrinos lose their energy travels undisturbed for many kilometers. To realize a large scale acoustic neutrino telescope, dedicated technology must be developed that allows for a deep sea sensor network. Fiber optic hydrophone technology provides a promising means to establish a large scale sensor network [1] with the proper sensitivity to detect the small signals from the neutrino interactions.

  1. 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

  2. Dual mode acoustic wave sensor for precise pressure reading

    NASA Astrophysics Data System (ADS)

    Mu, Xiaojing; Kropelnicki, Piotr; Wang, Yong; Randles, Andrew Benson; Chuan Chai, Kevin Tshun; Cai, Hong; Gu, Yuan Dong

    2014-09-01

    In this letter, a Microelectromechanical system acoustic wave sensor, which has a dual mode (lateral field exited Lamb wave mode and surface acoustic wave (SAW) mode) behavior, is presented for precious pressure change read out. Comb-like interdigital structured electrodes on top of piezoelectric material aluminium nitride (AlN) are used to generate the wave modes. The sensor membrane consists of single crystalline silicon formed by backside-etching of the bulk material of a silicon on insulator wafer having variable device thickness layer (5 μm-50 μm). With this principle, a pressure sensor has been fabricated and mounted on a pressure test package with pressure applied to the backside of the membrane within a range of 0 psi to 300 psi. The temperature coefficient of frequency was experimentally measured in the temperature range of -50 °C to 300 °C. This idea demonstrates a piezoelectric based sensor having two modes SAW/Lamb wave for direct physical parameter—pressure readout and temperature cancellation which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications using the dual mode behavior of the sensor and differential readout at the same time.

  3. Relaxation of Distributed Data Aggregation for Underwater Acoustic Sensor Networks

    DTIC Science & Technology

    2014-03-31

    Acoustic Sensor Networks Contract Report # AMBUSH.1.2 Contract # W7707-145675 M. Rabbat, M. Coates McGill University ( Montreal , QC, Canada) Fiscal...challenging. Chan- nel conditions change rapidly and high data-rate communications are generally not possi- ble. Consequently, protocols and mechanisms...Üstebay, D., and Coates, M. (2014), Distributed ensemble Kalman filtering, (Technical Report) McGill University, Montreal , Quebec. [8] Evensen, G

  4. An Acoustic Plate Mode Sensor for Biowarfare Toxins, Phase II

    DTIC Science & Technology

    1997-10-01

    Biological agents -- such as bacteria , bacterial toxins and viruses -- must be detected rapidly to allow their neutralization or the quick treatment of...Mode Sensor for Biowarfare Toxins PRINCIPAL INVESTIGATOR: Douglas J. McAllister, Ph.D. CONTRACTING ORGANIZATION: Biode, Incorporated Bangor, Maine...OF PAGES Acoustic Plate Mode, Biowarfare Toxins 54 16. PRICE CODE 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION

  5. DECAF - Density Estimation for Cetaceans from Passive Acoustic Fixed Sensors

    DTIC Science & Technology

    2010-01-01

    DECAF – Density Estimation for Cetaceans from passive Acoustic Fixed sensors Len Thomas CREEM, University of St Andrews, St Andrews, Fife, Scotland...REPORT DATE 2010 2. REPORT TYPE 3. DATES COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE DECAF - Density Estimation for Cetaceans from...Prescribed by ANSI Std Z39-18 LONG-TERM GOALS Determining the spatial density and distribution of cetacean (whale and dolphin) species is fundamental to

  6. 3D Underwater Imaging Using Vector Acoustic Sensors

    DTIC Science & Technology

    2007-12-01

    infidelity. Direc- tionality also can be lost when two waves from different directions arrive simultaneously. Figure 3 shows a hodograph of the direct...red) deviated substantially from the axis. The *-direction -0.2 -0.1 0 0.1 0.2 X-axis response Figure 3. Hodograph of the x...the sensor motions caused by the scattered waves from the targets. This hodograph illustrates the directional informa- tion in vector acoustic data

  7. High-sensitivity acoustic sensors from nanofibre webs

    PubMed Central

    Lang, Chenhong; Fang, Jian; Shao, Hao; Ding, Xin; Lin, Tong

    2016-01-01

    Considerable interest has been devoted to converting mechanical energy into electricity using polymer nanofibres. In particular, piezoelectric nanofibres produced by electrospinning have shown remarkable mechanical energy-to-electricity conversion ability. However, there is little data for the acoustic-to-electric conversion of electrospun nanofibres. Here we show that electrospun piezoelectric nanofibre webs have a strong acoustic-to-electric conversion ability. Using poly(vinylidene fluoride) as a model polymer and a sensor device that transfers sound directly to the nanofibre layer, we show that the sensor devices can detect low-frequency sound with a sensitivity as high as 266 mV Pa−1. They can precisely distinguish sound waves in low to middle frequency region. These features make them especially suitable for noise detection. Our nanofibre device has more than five times higher sensitivity than a commercial piezoelectric poly(vinylidene fluoride) film device. Electrospun piezoelectric nanofibres may be useful for developing high-performance acoustic sensors. PMID:27005010

  8. Microstructured polymer optical fibre sensors for opto-acoustic endoscopy

    NASA Astrophysics Data System (ADS)

    Broadway, Christian; Gallego, Daniel; Pospori, Andreas; Zubel, Michal; Webb, David J.; Sugden, Kate; Carpintero, Guillermo; Lamela, Horacio

    2016-04-01

    Opto-acoustic imaging is a growing field of research in recent years, providing functional imaging of physiological biomarkers, such as the oxygenation of haemoglobin. Piezo electric transducers are the industry standard detector for ultrasonics, but their limited bandwidth, susceptibility to electromagnetic interference and their inversely proportional sensitivity to size all affect the detector performance. Sensors based on polymer optical fibres (POF) are immune to electromagnetic interference, have lower acoustic impedance and a reduced Young's Modulus compared to silica fibres. Furthermore, POF enables the possibility of a wideband sensor and a size appropriate to endoscopy. Micro-structured POF (mPOF) used in an interferometric detector has been shown to be an order of magnitude more sensitive than silica fibre at 1 MHz and 3 times more sensitive at 10 MHz. We present the first opto-acoustic measurements obtained using a 4.7mm PMMA mPOF Bragg grating with a fibre diameter of 130 μm and present the lateral directivity pattern of a PMMA mPOF FBG ultrasound sensor over a frequency range of 1-50 MHz. We discuss the impact of the pattern with respect to the targeted application and draw conclusions on how to mitigate the problems encountered.

  9. Distribution theory approach to implementing directional acoustic sensors.

    PubMed

    Schmidlin, Dean J

    2010-01-01

    The objective of directional acoustic sensors is to provide high directivity while occupying a small amount of space. An idealized point sensor achieves this objective from a knowledge of the spatial partial derivatives of acoustic pressure at a point in space. Direct measurement of these derivatives is difficult in practice. Consequently, it is expedient to come up with indirect methods. The use of pressure sensors to construct finite-difference approximations is an example of such a method. This paper utilizes the theory of distributions to derive another indirect method for estimating the various spatial partial derivatives of the pressure. This alternate method is then used to construct a multichannel filter which processes the acoustic pressure by mean of three-dimensional integral transforms throughout a 6epsilon-length cube centered at the origin. The output of the multichannel filter is a spatially and temporally filtered version of the pressure at the origin. The temporal filter is a lowpass Gaussian filter whose bandwidth is inversely proportional to epsilon. Finally, the lattice method for numerical multiple integration is utilized to develop a discrete-spatial version of the multichannel filter.

  10. Method for Fabricating Piezoelectric Polymer Acoustic Sensors

    NASA Technical Reports Server (NTRS)

    Hall, Thomas E., Jr. (Inventor); Bryant, Timothy D. (Inventor)

    1998-01-01

    A method for forming a sensor includes providing a first and a second film and bonding an internal connection tab there between. The internal connection tab is positioned between the inner surfaces of the first and second film. Then, a conductive adhesive is applied to either the tab or to the inner film surfaces such that the inner surfaces of the film and the tab are electrically connected. Finally, the films are pressed together to bond the film together with the internal connection tab in between.

  11. Structural configuration study for an acoustic wave sensor

    NASA Astrophysics Data System (ADS)

    Zhang, Biaobiao

    A continuous structure has several response characteristics that make it a candidate for a sensor used to locate an acoustic source. Primary goals in developing such a sensor structure are to ensure that the response is rich enough to provide information about the impinging acoustic wave and to detect the direction of travel without being too sensitive to background noise. As such, there are several factors that must be examined with regard to sensor configuration and measurement requirements. This dissertation describes a set of studies that examine various configuration requirements for such a sensor. Some of the parameters of interest include the size, or aperture of the structure, boundary conditions, material properties, and thickness. The response of the structure to transient sinusoidal wave excitations will be examined analytically. The time-domain response of an Euler-Bernoulli beam excited by a traveling sinusoidal excitation is obtained based on modal superposition and verified by using a finite element method. Then, an approach using simple basis functions will be applied to achieve the goal of more efficient response and force identification. The moving force is identified in the time domain by extending previous inverse approaches. The Tikhonov regularization technique provides bounds to the ill-conditioned results in the identification problem. Both simulated displacement and velocity are considered for use in the inverse. To evaluate the method and examine various configurations, simulations with different numbers of sinusoidal half-cycles exciting the sensor structure are studied. Various levels of random noise are also added to the simulated displacements and velocities responses in order to study the effect of noise in moving wave load identification. Such a new approach in acoustic sensing has applications in the areas of security and disaster recovery.

  12. Fatigue crack monitoring with coupled piezoelectric film acoustic emission sensors

    NASA Astrophysics Data System (ADS)

    Zhou, Changjiang

    Fatigue-induced cracking is a commonly seen problem in civil infrastructures reaching their original design life. A number of high-profile accidents have been reported in the past that involved fatigue damage in structures. Such incidences often happen without prior warnings due to lack of proper crack monitoring technique. In order to detect and monitor the fatigue crack, acoustic emission (AE) technique, has been receiving growing interests recently. AE can provide continuous and real-time monitoring data on damage progression in structures. Piezoelectric film AE sensor measures stress-wave induced strain in ultrasonic frequency range and its feasibility for AE signal monitoring has been demonstrated recently. However, extensive work in AE monitoring system development based on piezoelectric film AE sensor and sensor characterization on full-scale structures with fatigue cracks, have not been done. A lack of theoretical formulations for understanding the AE signals also hinders the use of piezoelectric film AE sensors. Additionally, crack detection and source localization with AE signals is a very important area yet to be explored for this new type of AE sensor. This dissertation presents the results of both analytical and experimental study on the signal characteristics of surface stress-wave induced AE strain signals measured by piezoelectric film AE sensors in near-field and an AE source localization method based on sensor couple theory. Based on moment tensor theory, generalized expression for AE strain signal is formulated. A special case involving the response of piezoelectric film AE sensor to surface load is also studied, which could potentially be used for sensor calibration of this type of sensor. A new concept of sensor couple theory based AE source localization technique is proposed and validated with both simulated and experimental data from fatigue test and field monitoring. Two series of fatigue tests were conducted to perform fatigue crack

  13. Mass sensing AlN sensors for waste water monitoring

    NASA Astrophysics Data System (ADS)

    Porrazzo, R.; Potter, G.; Lydecker, L.; Foraida, Z.; Gattu, S.; Tokranova, N.; Castracane, J.

    2014-08-01

    Monitoring the presence of nanomaterials in waste water from semiconductor facilities is a critical task for public health organizations. Advanced semiconductor technology allows the fabrication of sensitive piezoelectric-based mass sensors with a detection limit of less than 1.35 ng/cm2 of nanomaterials such as nanoparticles of alumina, amorphous silica, ceria, etc. The interactions between acoustic waves generated by the piezoelectric sensor and nanomaterial mass attached to its surface define the sensing response as a shift in the resonant frequency. In this article the development and characterization of a prototype AlN film bulk acoustic resonator (FBAR) are presented. DC reactive magnetron sputtering was used to create tilted c-axis oriented AlN films to generate shear waves which don't propagate in liquids thus minimizing the acoustic losses. The high acoustic velocity of AlN over quartz allows an increase in resonance frequency in comparison with a quartz crystal microbalance (QCM) and results in a higher frequency shift per mass change, and thus greater sensitivity. The membrane and electrodes were fabricated using state of the art semiconductor technology. The device surface functionalization was performed to demonstrate selectivity towards a specific nanomaterial. As a result, the devices were covered with a "docking" layer that allows the nanomaterials to be selectively attached to the surface. This was achieved using covalent modification of the surface, specifically targeting ZnO nanoparticles. Our functionalization approach was tested using two different types of nanoparticles, and binding specificity was confirmed with various analytical techniques.

  14. Fast Response and High Sensitivity ZnO/glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing Layer

    PubMed Central

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J. K.

    2014-01-01

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 sec rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications. PMID:25425458

  15. Fast Response and High Sensitivity ZnO/glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing Layer

    NASA Astrophysics Data System (ADS)

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J. K.

    2014-11-01

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 sec rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications.

  16. Fast response and high sensitivity ZnO/glass surface acoustic wave humidity sensors using graphene oxide sensing layer.

    PubMed

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J K

    2014-11-26

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 sec rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications.

  17. Robotic vehicle uses acoustic sensors for voice detection and diagnostics

    NASA Astrophysics Data System (ADS)

    Young, Stuart H.; Scanlon, Michael V.

    2000-07-01

    An acoustic sensor array that cues an imaging system on a small tele- operated robotic vehicle was used to detect human voice and activity inside a building. The advantage of acoustic sensors is that it is a non-line of sight (NLOS) sensing technology that can augment traditional LOS sensors such as visible and IR cameras. Acoustic energy emitted from a target, such as from a person, weapon, or radio, will travel through walls and smoke, around corners, and down corridors, whereas these obstructions would cripple an imaging detection system. The hardware developed and tested used an array of eight microphones to detect the loudest direction and automatically setter a camera's pan/tilt toward the noise centroid. This type of system has applicability for counter sniper applications, building clearing, and search/rescue. Data presented will be time-frequency representations showing voice detected within rooms and down hallways at various ranges. Another benefit of acoustics is that it provides the tele-operator some situational awareness clues via low-bandwidth transmission of raw audio data for the operator to interpret with either headphones or through time-frequency analysis. This data can be useful to recognize familiar sounds that might indicate the presence of personnel, such as talking, equipment, movement noise, etc. The same array also detects the sounds of the robot it is mounted on, and can be useful for engine diagnostics and trouble shooting, or for self-noise emanations for stealthy travel. Data presented will characterize vehicle self noise over various surfaces such as tiles, carpets, pavement, sidewalk, and grass. Vehicle diagnostic sounds will indicate a slipping clutch and repeated unexpected application of emergency braking mechanism.

  18. Localization with a mobile beacon in underwater acoustic sensor networks.

    PubMed

    Lee, Sangho; Kim, Kiseon

    2012-01-01

    Localization is one of the most important issues associated with underwater acoustic sensor networks, especially when sensor nodes are randomly deployed. Given that it is difficult to deploy beacon nodes at predetermined locations, localization schemes with a mobile beacon on the sea surface or along the planned path are inherently convenient, accurate, and energy-efficient. In this paper, we propose a new range-free Localization with a Mobile Beacon (LoMoB). The mobile beacon periodically broadcasts a beacon message containing its location. Sensor nodes are individually localized by passively receiving the beacon messages without inter-node communications. For location estimation, a set of potential locations are obtained as candidates for a node's location and then the node's location is determined through the weighted mean of all the potential locations with the weights computed based on residuals.

  19. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    NASA Technical Reports Server (NTRS)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    Under NASA's Advanced Air Vehicles Program the Advanced Air Transport Technology (AATT) Project is investigating flutter effects on aeroelastic wings. To support that work a new method for measuring vibrations due to flutter has been developed. The method employs low power Surface Acoustic Wave (SAW) sensors. To demonstrate the ability of the SAW sensor to detect flutter vibrations the sensors were attached to a Carbon fiber-reinforced polymer (CFRP) composite panel which was vibrated at six frequencies from 1Hz to 50Hz. The SAW data was compared to accelerometer data and was found to resemble sine waves and match each other closely. The SAW module design and results from the tests are presented here.

  20. Following butter flavour deterioration with an acoustic wave sensor.

    PubMed

    Gaspar, Cláudia R B S; Gomes, M Teresa S R

    2012-09-15

    Off-flavours develop naturally in butter and the process is accelerated by heat. An acoustic wave sensor was used to detect the aroma compounds evolved from heated butter and the results have shown that registered marked changes were coincident to odour changes detected by sensory analysis. The flavour compounds have also been analysed by GC/MS for identification. The response of the sensor was fully characterized in terms of the sensitivity to each of the identified compounds, and sensitivities of the system SPME/sensor were compared with the sensitivities of the system SPME/GC/MS. It was found that the sensor analytical system was more sensitive to methylketones than to fatty acids. The SPME/GC/MS system also showed the highest sensitivity to 2-heptanone, followed by 2-nonanone, but third place was occupied by undecanone and butanoic acid, to which the sensor showed moderate sensitivity. 2-heptanone was found to be an appropriate model compound to follow odour changes till the 500 h, and the lower sensitivity of the sensor to butanoic acid showed to be a positive characteristic, as saturation was prevented, and other more subtle changes in the flavour could be perceived.

  1. Adaptation of PWAS transducers to acoustic emission sensors

    NASA Astrophysics Data System (ADS)

    Yu, Lingyu; Momeni, Sepandarmaz; Godinez, Valery; Giurgiutiu, Victor

    2011-04-01

    Piezoelectric wafer active sensors (PWAS) are non-intrusive transducers that can convert mechanical energy into electrical energy, and vice versa. They are well known for their dual use as either actuators or sensors. Though PWAS has shown great potential for active sensing, its capability for acoustic emission (AE) detection has not yet been exploited. In the reported work, we have explored the implementation of PWAS transducers for both passive (AE sensors) and active (in-situ ultrasonic transducers) sensing using a single PWAS network. The objective of the work presented in this paper is to adapt PWAS as AE sensors and compare it to the commercially available AE transducers such as PAC R15. An experiment has been designed to show how PWAS can be used for AE detection and the results were compared to a standard AE sensor, PAC R15I. Tests on compact tension specimens have also been conducted to show PWAS capability to pick up AE events during fatigue loading. PWAS field installation technology has been tested with packaging similar to that used for traditional strain gauges. The performance of packaged PWAS has been compared with that of conventional AE transducers R15I. We have found that PWAS not only can detect the presence of AE events but also can provide a wide frequency bandwidth. At this stage, PWAS underperforms the commercial AE sensors. To make PWAS ready for field test, signal to noise ratio needs to be significantly improved.

  2. Soldier detection using unattended acoustic and seismic sensors

    NASA Astrophysics Data System (ADS)

    Naz, P.; Hengy, S.; Hamery, P.

    2012-06-01

    During recent military conflicts, as well as for security interventions, the urban zone has taken a preponderant place. Studies have been initiated in national and in international programs to stimulate the technical innovations for these specific scenarios. For example joint field experiments have been organized by the NATO group SET-142 to evaluate the capability for the detection and localization of snipers, mortars or artillery guns using acoustic devices. Another important operational need corresponds to the protection of military sites or buildings. In this context, unattended acoustic and seismic sensors are envisaged to contribute to the survey of specific points by the detection of approaching enemy soldiers. This paper describes some measurements done in an anechoic chamber and in free field to characterize typical sounds generated by the soldier activities (walking, crawling, weapon handling, radio communication, clothing noises...). Footstep, speech and some specific impulsive sounds are detectable at various distances from the source. Such detection algorithms may be easily merged with the existing weapon firing detection algorithms to provide a more generic "battlefield acoustic" early warning system. Results obtained in various conditions (grassy terrain, gravel path, road, forest) will be presented. A method to extrapolate the distances of detection has been developed, based on an acoustic propagation model and applied to the laboratory measurements.

  3. PREDICTIVE MODELING OF ACOUSTIC SIGNALS FROM THERMOACOUSTIC POWER SENSORS (TAPS)

    SciTech Connect

    Dumm, Christopher M.; Vipperman, Jeffrey S.

    2016-06-30

    Thermoacoustic Power Sensor (TAPS) technology offers the potential for self-powered, wireless measurement of nuclear reactor core operating conditions. TAPS are based on thermoacoustic engines, which harness thermal energy from fission reactions to generate acoustic waves by virtue of gas motion through a porous stack of thermally nonconductive material. TAPS can be placed in the core, where they generate acoustic waves whose frequency and amplitude are proportional to the local temperature and radiation flux, respectively. TAPS acoustic signals are not measured directly at the TAPS; rather, they propagate wirelessly from an individual TAPS through the reactor, and ultimately to a low-power receiver network on the vessel’s exterior. In order to rely on TAPS as primary instrumentation, reactor-specific models which account for geometric/acoustic complexities in the signal propagation environment must be used to predict the amplitude and frequency of TAPS signals at receiver locations. The reactor state may then be derived by comparing receiver signals to the reference levels established by predictive modeling. In this paper, we develop and experimentally benchmark a methodology for predictive modeling of the signals generated by a TAPS system, with the intent of subsequently extending these efforts to modeling of TAPS in a liquid sodium environmen

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

    NASA Astrophysics Data System (ADS)

    Scanlon, Michael

    2002-11-01

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

  5. Generalized concept of shear horizontal acoustic plate mode and Love wave sensors

    NASA Astrophysics Data System (ADS)

    McHale, Glen

    2003-11-01

    An approach to mass and liquid sensitivity for both the phase velocity and insertion loss of shear mode acoustic wave sensors based on the dispersion equations for layered systems is outlined. The approach is sufficiently general to allow for viscoelastic guiding layers. An equation for the phase velocity and insertion loss sensitivities is given which depends on the slope of the complex phase velocity dispersion curves. This equation contains the equivalent of the Sauerbrey and Kanazawa equations for loading of a quartz crystal microbalance by rigid mass and Newtonian liquids, respectively, and also describes surface loading by viscoelastic layers. The theoretical approach can be applied to a four-layer system, with any of the four layers being viscoelastic, so that mass deposition from a liquid can also be modelled. The theoretical dispersion equation based approach to layer-guided shear horizontal acoustic wave modes on finite substrates presented in this work provides a unified view of Love wave and shear horizontal acoustic plate mode (SH-APM) devices, which have been generally regarded as distinct in sensor research. It is argued that SH-APMs with guiding layers possessing shear acoustic speeds lower than that of the substrate and Love waves are two branches of solution of the same dispersion equation. The layer guided SH-APMs have a phase velocity higher than that of the substrate and the Love waves a phase velocity lower than that of the substrate. Higher-order Love wave modes are continuations of the layer-guided SH-APMs. The generalized concept of SH-APMs and Love waves provides a basis for understanding the change in sensitivity with higher-frequency operation and the relationship between multiple modes in Love wave sensors. It also explains why a relatively thick layer of a high-loss polymer can be used as a waveguide layer and so extends the range of materials that can be considered experimentally. Moreover, it is predicted that a new type of sensor, a

  6. Langasite Surface Acoustic Wave Sensors: Fabrication and Testing

    SciTech Connect

    Zheng, Peng; Greve, David W.; Oppenheim, Irving J.; Chin, Tao-Lun; Malone, Vanessa

    2012-02-01

    We report on the development of harsh-environment surface acoustic wave sensors for wired and wireless operation. Surface acoustic wave devices with an interdigitated transducer emitter and multiple reflectors were fabricated on langasite substrates. Both wired and wireless temperature sensing was demonstrated using radar-mode (pulse) detection. Temperature resolution of better than ±0.5°C was achieved between 200°C and 600°C. Oxygen sensing was achieved by depositing a layer of ZnO on the propagation path. Although the ZnO layer caused additional attenuation of the surface wave, oxygen sensing was accomplished at temperatures up to 700°C. The results indicate that langasite SAW devices are a potential solution for harsh-environment gas and temperature sensing.

  7. Single-sensor multispeaker listening with acoustic metamaterials

    PubMed Central

    Xie, Yangbo; Tsai, Tsung-Han; Konneker, Adam; Popa, Bogdan-Ioan; Brady, David J.; Cummer, Steven A.

    2015-01-01

    Designing a “cocktail party listener” that functionally mimics the selective perception of a human auditory system has been pursued over the past decades. By exploiting acoustic metamaterials and compressive sensing, we present here a single-sensor listening device that separates simultaneous overlapping sounds from different sources. The device with a compact array of resonant metamaterials is demonstrated to distinguish three overlapping and independent sources with 96.67% correct audio recognition. Segregation of the audio signals is achieved using physical layer encoding without relying on source characteristics. This hardware approach to multichannel source separation can be applied to robust speech recognition and hearing aids and may be extended to other acoustic imaging and sensing applications. PMID:26261314

  8. Current capability of a matured disposable acoustic sensor network

    NASA Astrophysics Data System (ADS)

    Beale, D. A. R.; Geddes, N. J., II; Hume, A.; Gray, A. J.

    2006-05-01

    In response to the needs of the UK MOD QinetiQ have designed, developed and trialled an ad-hoc, self organising network of acoustic nodes for in-depth deployment that can detect and track military targets in a range of environments and for all types of weapon locating. Research conducted has shown that disposable technologies are sufficiently mature to provide a useful military capability. Work this year has included a 3 month series of trials to exercise the prototype equipment and has provided an indication of in-service capability across a broad range of environments. This paper will discuss the scientific approach that was applied to the development of the equipment, from early laboratory development through to the prototype sensor network deployment in operationally representative environments. Highlights from the trials have been provided. New findings from the fusion of a low cost thermal imager that can be cued by the acoustic network are also discussed.

  9. Vibro-acoustic control with a distributed sensor network.

    PubMed

    Frampton, Kenneth D

    2006-04-01

    The purpose of this work is to demonstrate the ability of a distributed control system, based on a smart sensor network, to reduce acoustic radiation from a vibrating structure. The platform from which control is effected consists of a network of smart sensors, each referred to as a node. Each node possesses its own computational capability, sensor, actuator and the ability to communicate with other nodes via a wired or wireless network. The primary focus of this work is to employ existing group management middleware concepts to enable vibro-acoustic control with such a distributed network. Group management middleware is distributed software that provides for the establishment and maintenance of groups of distributed nodes and that provides for the network communication among such groups. The control objective is met by designing distributed feedback compensators that take advantage of node groups in order to effect their control. The node groups are formed based on physical proximity. The global control objective is to minimize the radiated sound power from a rectangular plate. Results of this investigation demonstrate that such a distributed control system can achieve attenuations comparable to those achieved by a centralized controller.

  10. Calibration of sensors for acoustic detection of neutrinos

    NASA Astrophysics Data System (ADS)

    Ardid, M.; Bou-Cabo, M.; Espinosa, V.; Martínez-Mora, J.; Camarena, F.; Alba, J.

    2007-09-01

    Calibration of sensors is an important task for the acoustic detection of neutrinos. Different approaches have been tried and used (calibrated hydrophones, resistors, powerful lasers, light bulbs explosion, etc.) We propose some methods for calibration that can be used in both the lab and the telescope ("in situ"). In this paper, different studies following these methods and their results are reported. First, we describe the reciprocity calibration method for acoustic sensors. Since it is a simple method and calibrated hydrophones are not needed, this technique is accessible for any lab. Moreover, the technique could be used to calibrate the sensors of a neutrino telescope just by using themselves (reciprocally). A comparison of this technique using different kind of signals (MLS, TSP, tone bursts, white noise), and in different propagation conditions is presented. The limitations of the technique are shown, as well as some possibilities to overcome them. The second aspect treated is the obtaining of neutrinolike signals for calibration. Probably, the most convenient way to do it would be to generate these signals from transducers directly. Since transducers do not usually have a flat frequency response, distortion is produced, and neutrino-like signals could be difficult to achieve. We present some equalization techniques to offset this effect. In this sense, the use of inverse filter based in Mourjopoulos theory seems to be quite convenient.

  11. Structural tests using a MEMS acoustic emission sensor

    NASA Astrophysics Data System (ADS)

    Oppenheim, Irving J.; Greve, David W.; Ozevin, Didem; Hay, D. Robert; Hay, Thomas R.; Pessiki, Stephen P.; Tyson, Nathan L.

    2006-03-01

    In a collaborative project at Lehigh and Carnegie Mellon, a MEMS acoustic emission sensor was designed and fabricated as a suite of six resonant-type capacitive transducers in the frequency range between 100 and 500 kHz. Characterization studies showed good comparisons between predicted and experimental electro-mechanical behavior. Acoustic emission events, simulated experimentally in steel ball impact and in pencil lead break tests, were detected and source localization was demonstrated. In this paper we describe the application of the MEMS device in structural testing, both in laboratory and in field applications. We discuss our findings regarding housing and mounting (acoustic coupling) of the MEMS device with its supporting electronics, and we then report the results of structural testing. In all tests, the MEMS transducers were used in parallel with commercial acoustic emission sensors, which thereby serve as a benchmark and permit a direct observation of MEMS device functionality. All tests involved steel structures, with particular interest in propagation of existing cracks or flaws. A series of four laboratory tests were performed on beam specimens fabricated from two segments (Grade 50 steel) with a full penetration weld (E70T-4 electrode material) at midspan. That weld region was notched, an initial fatigue crack was induced, and the specimens were then instrumented with one commercial transducer and with one MEMS device; data was recorded from five individual transducers on the MEMS device. Under a four-point bending test, the beam displayed both inelastic behavior and crack propagation, including load drops associated with crack instability. The MEMS transducers detected all instability events as well as many or most of the acoustic emissions occurring during plasticity and stable crack growth. The MEMS transducers were less sensitive than the commercial transducer, and did not detect as many events, but the normalized cumulative burst count obtained

  12. Acoustic Sensors for Fission Gas Characterization in MTR Harsh Environment

    NASA Astrophysics Data System (ADS)

    Very, F.; Rosenkrantz, E.; Fourmentel, D.; Destouches, C.; Villard, J. F.; Combette, P.; Ferrandis, J. Y.

    Our group is now working for more than 15 years, in a close partnership with CEA, on the development of acoustic sensors devoted to the characterization of fission gas release for in-pile experiments in Material Testing Reactor. First of all, we will present the main principle of the method and the result of a first succeed experiment called REMORA 3 used to differentiate helium and fission gas released kinetics under transient operating condition [1]. Then we will present our new researches involving thick film transducers produced by screen-printing process in order to propose piezoelectric structures for harsh temperature and irradiation measurements in new MTR reactor.

  13. Simulation and Experimental Elaboration of Acoustic Sensors for Mobile Robots

    DTIC Science & Technology

    2005-05-01

    Wheeled mobile robot “ Argonaut -2” equipped with acoustic audition systems is shown on Fig. 1. The left picture shows the 1st release of a system, and the...2 RTO-MP-SET-092 UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED Figure 1: The “ Argonaut -2” Mobile Robot Equipped with Audition Sensors. 2.1...onboard part of control system is given on Fig. 2. Figure 2: Control System of a Robot “ Argonaut -2”. Simulation and Experimental Elaboration of

  14. Design of acoustic wave biochemical sensors using micro-electro-mechanical systems

    NASA Astrophysics Data System (ADS)

    Valentine, Jane E.; Przybycien, Todd M.; Hauan, Steinar

    2007-03-01

    Acoustic wave biochemical sensors work by detecting the frequency shifts resulting from the binding of target molecules to a functionalized resonator. Resonator types currently in use or under development include macroscopic quartz crystal microbalances (QCMs) as well as a number of different integrated Micro-electro-mechanical Systems (MEMS) structures. Due to an increased resonator surface area to mass ratio, we believe that membrane-based MEMS systems are particularly promising with regard to sensitivity. Prototypes have been developed [S. Hauan et al., U.S. Patent Application (filed 6 Nov. 2003)] and preliminary calculations [M. J. Bartkovsky et al., paper 385e presented at the AIChE Annual Meeting, Nov. 2003; J. E. Valentine et al., paper 197h presented at the AICHE Annual Meeting, Nov. 2003] indicate significant improvements over other methods, both macroscopic and MEMS based. In this article we describe our work on a MEMS-based acoustic wave biochemical sensor using a membrane resonator. We demonstrate the effects of spatial distributions of mass on the membrane on sensitivity and show how to use this spatial sensitivity to detect multiple targets simultaneously. To do so we derive a function approximating the membrane response surface to spatial mass loadings under the applicable range of conditions. We verify the agreement using finite element methods, and present our initial sensitivity calculations demonstrating the advantages of variable mass loadings.

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

    PubMed Central

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

    2015-01-01

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

  16. A Mobile Acoustic Subsurface Sensing (MASS) System for Rapid Roadway Assessment

    PubMed Central

    Lu, Yifeng; Zhang, Yi; Cao, Yinghong; McDaniel, J. Gregory; Wang, Ming L.

    2013-01-01

    Surface waves are commonly used for vibration-based nondestructive testing for infrastructure. Spectral Analysis of Surface Waves (SASW) has been used to detect subsurface properties for geologic inspections. Recently, efforts were made to scale down these subsurface detection approaches to see how they perform on small-scale structures such as concrete slabs and pavements. Additional efforts have been made to replace the traditional surface-mounted transducers with non-contact acoustic transducers. Though some success has been achieved, most of these new approaches are inefficient because they require point-to-point measurements or off-line signal analysis. This article introduces a Mobile Acoustic Subsurface Sensing system as MASS, which is an improved surface wave based implementation for measuring the subsurface profile of roadways. The compact MASS system is a 3-wheeled cart outfitted with an electromagnetic impact source, distance register, non-contact acoustic sensors and data acquisition/processing equipment. The key advantage of the MASS system is the capability to collect measurements continuously at walking speed in an automatic way. The fast scan and real-time analysis advantages are based upon the non-contact acoustic sensing and fast air-coupled surface wave analysis program. This integration of hardware and software makes the MASS system an efficient mobile prototype for the field test. PMID:23698266

  17. Characterization Test Report for the Mnemonics-UCS Wireless Surface Acoustic Wave Sensor System

    NASA Technical Reports Server (NTRS)

    Duncan, Joshua J.; Youngquist, Robert C.

    2013-01-01

    The scope of this testing includes the Surface Acoustic Wave Sensor System delivered to KSC: two interrogator (transceiver) systems, four temperature sensors, with wooden mounting blocks, two antennas, two power supplies, network cables, and analysis software. Also included are a number of additional temperature sensors and newly-developed hydrogen sensors

  18. A Survey on Underwater Acoustic Sensor Network Routing Protocols

    PubMed Central

    Li, Ning; Martínez, José-Fernán; Meneses Chaus, Juan Manuel; Eckert, Martina

    2016-01-01

    Underwater acoustic sensor networks (UASNs) have become more and more important in ocean exploration applications, such as ocean monitoring, pollution detection, ocean resource management, underwater device maintenance, etc. In underwater acoustic sensor networks, since the routing protocol guarantees reliable and effective data transmission from the source node to the destination node, routing protocol design is an attractive topic for researchers. There are many routing algorithms have been proposed in recent years. To present the current state of development of UASN routing protocols, we review herein the UASN routing protocol designs reported in recent years. In this paper, all the routing protocols have been classified into different groups according to their characteristics and routing algorithms, such as the non-cross-layer design routing protocol, the traditional cross-layer design routing protocol, and the intelligent algorithm based routing protocol. This is also the first paper that introduces intelligent algorithm-based UASN routing protocols. In addition, in this paper, we investigate the development trends of UASN routing protocols, which can provide researchers with clear and direct insights for further research. PMID:27011193

  19. A Survey on Underwater Acoustic Sensor Network Routing Protocols.

    PubMed

    Li, Ning; Martínez, José-Fernán; Meneses Chaus, Juan Manuel; Eckert, Martina

    2016-03-22

    Underwater acoustic sensor networks (UASNs) have become more and more important in ocean exploration applications, such as ocean monitoring, pollution detection, ocean resource management, underwater device maintenance, etc. In underwater acoustic sensor networks, since the routing protocol guarantees reliable and effective data transmission from the source node to the destination node, routing protocol design is an attractive topic for researchers. There are many routing algorithms have been proposed in recent years. To present the current state of development of UASN routing protocols, we review herein the UASN routing protocol designs reported in recent years. In this paper, all the routing protocols have been classified into different groups according to their characteristics and routing algorithms, such as the non-cross-layer design routing protocol, the traditional cross-layer design routing protocol, and the intelligent algorithm based routing protocol. This is also the first paper that introduces intelligent algorithm-based UASN routing protocols. In addition, in this paper, we investigate the development trends of UASN routing protocols, which can provide researchers with clear and direct insights for further research.

  20. Acoustic sensors on small robots for the urban environment

    NASA Astrophysics Data System (ADS)

    Young, Stuart H.; Scanlon, Michael V.

    2005-05-01

    As the Army transforms to the Future Force, particular attention must be paid to operations in Complex and Urban Terrain. Because our adversaries realize that we don't have battlefield dominance in the urban environment, and because population growth and migration to urban environments is still on the increase, our adversaries will continue to draw us into operations in the urban environment. The Army Research Laboratory (ARL) is developing technology to equip our soldiers for the urban operations of the future. Sophisticated small robotic platforms with diverse sensor suites will be an integral part of the Future Force, and must be able to collaborate not only amongst themselves but also with their manned partners. The use of acoustic sensors on robotic platforms, as shown in this paper, will greatly aid the soldiers of the future force in performing numerous types of missions including Reconnaissance, Surveillance, and Target Acquisition (RSTA) by providing situational awareness, particularly to the dismounted soldier operating in the urban environment. The work conducted by the Army Research Laboratory, discussed in this paper will be transitioned to the FCS-Small Unattended Ground Vehicle (SUGV) program and FFW. The Army Research Laboratory is already working with these programs to ensure a feasible migration path. This paper focuses on four areas relating to acoustic sensing on robots for the urban environment as demonstrated at the DoD Horizontal Fusion Portfolio"s Warriors Edge (WE) Quantum Leap II (QL II) demonstration at Ft Benning, GA in August, 2004: small (man-portable) robot detection, mule-sized robot detection, sensor fusion across multiple platforms, and soldier/robot team interaction.

  1. Proceedings of the Workshop on Directional Acoustic Sensors Held in Newport, Rhode Island on 17-18 April 2001

    DTIC Science & Technology

    2001-04-18

    Corporation EDO Directional Acoustic Sensor Technology Dr. Bruce Abraham, Anteon Corporation Directional Hydrophones in Towed System 01... EDO Directional Acoustic Sensor Technology P. David Baird Systems Engineering Department EDO Electro-Ceramics Products...Salt Lake City, Utah 84115 1 EDO Directional Acoustic Sensor Technology P. David Baird Systems Engineering Department EDO Electro

  2. Guided shear horizontal surface acoustic wave sensors for chemical and biochemical detection in liquids.

    PubMed

    Josse, F; Bender, F; Cernose, R W

    2001-12-15

    The design and performance of guided shear horizontal surface acoustic wave (guided SH-SAW) devices on LiTaO3 substrates are investigated for high-sensitivity chemical and biochemical sensors in liquids. Despite their structural similarity to Rayleigh SAW, SH-SAWs often propagate slightly deeper within the substrate, hence preventing the implementation of high-sensitivity detectors. The device sensitivity to mass and viscoelastic loading is increased using a thin guiding layer on the device surface. Because of their relatively low shear wave velocity, various polymers including poly(methyl methacrylate) (PMMA) and cyanoethyl cellulose (cured or cross-linked) are investigated as the guiding layers to trap the acoustic energy near the sensing surface. The devices have been tested in biosensing and chemical sensing experiments. Suitable design principles for these applications are discussed with regard to wave guidance, electrical passivation of the interdigital transducers from the liquid environments, acoustic loss, and sensor signal distortion. In biosensing experiments, using near-optimal PMMA thickness of approximately 2 microm, mass sensitivity greater than 1500 Hz/(ng/mm2) is demonstrated, resulting in a minimum detection limit less than 20 pg/mm2. For chemical sensor experiments, it is found that optimal waveguide thickness must be modified to account for the chemically sensitive layer which also acts to guide the SH-SAW. A detection limit of 780 (3 x peak-to-peak noise) or 180 ppb (3 x rms noise) is estimated from the present measurements for some organic compounds in water.

  3. Development of Magnetically Excited Flexural Plate Wave Devices for Implementation as Physical, Chemical, and Acoustic Sensors, and as Integrated Micro-Pumps for Sensored Systems

    NASA Astrophysics Data System (ADS)

    Schubert, W. K.; Mitchell, M. A.; Graf, D. C.; Shul, R. J.

    2002-05-01

    The magnetically excited flexural plate wave (mag-FPW) device has great promise as a versatile sensor platform. FPW's can have better sensitivity at lower operating frequencies than surface acoustic wave (SAW) devices. Lower operating frequency simplifies the control electronics and makes integration of sensor with electronics easier. Magnetic rather than piezoelectric excitation of the FPW greatly simplifies the device structure and processing by eliminating the need for piezoelectric thin films, also simplifying integration issues. The versatile mag-FPW resonator structure can potentially be configured to fulfill a number of critical functions in an autonomous sensored system. As a physical sensor, the device can be extremely sensitive to temperature, fluid flow, strain, acceleration and vibration. By coating the membrane with self-assembled monolayers (SAMs), or polymer films with selective absorption properties (originally developed for SAW sensors), the mass sensitivity of the FPW allows it to be used as biological or chemical sensors. Yet another critical need in autonomous sensor systems is the ability to pump fluid. FPW structures can be configured as micro-pumps. This report describes work done to develop mag-FPW devices as physical, chemical, and acoustic sensors, and as micro-pumps for both liquid and gas-phase analytes to enable new integrated sensing platform.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  5. Development of a novel odor measurement system using gas chromatography with surface acoustic wave sensor.

    PubMed

    Staples, Edward J; Viswanathan, Shekar

    2008-12-01

    This paper describes a novel odor measurement system for creating arrays of virtual chemical sensors with nonoverlapping responses using ultrahigh-speed gas chromatography with a surface acoustic wave sensor (GC/SAW). This GC/SAW system provides high-resolution two-dimensional olfactory images for easy recognition of many complex odors. Separation and quantification of the individual chemicals within an odor is performed in seconds. Using a solid-state mass-sensitive detector, picogram sensitivity, universal nonpolar selectivity, and electronically variable sensitivity are achieved. An integrated vapor preconcentrator coupled with the electronically variable detector allows the system to measure vapor concentrations spanning 6 or more orders of magnitude. The system attributes of high speed, accuracy, and precision provide a cost-effective and complimentary tool for traditional sensory evaluations.

  6. An acoustic transmission sensor for the longitudinal viscosity of fluids.

    PubMed

    Antlinger, Hannes; Clara, Stefan; Beigelbeck, Roman; Cerimovic, Samir; Keplinger, Franz; Jakoby, Bernhard

    2013-11-01

    Physical fluid parameters like viscosity, mass density and sound velocity can be determined utilizing ultrasonic sensors. We introduce the concept of a recently devised transmission based sensor utilizing pressure waves to determine the longitudinal viscosity, bulk viscosity, and second coefficient of viscosity of a sample fluid in a test chamber. A model is presented which allows determining these parameters from measurement values by means of a fit. The setup is particularly suited for liquids featuring higher viscosities for which measurement data are scarcely available to date. The setup can also be used to estimate the sound velocity in a simple manner from the phase of the transfer function.

  7. An acoustic transmission sensor for the longitudinal viscosity of fluids

    PubMed Central

    Antlinger, Hannes; Clara, Stefan; Beigelbeck, Roman; Cerimovic, Samir; Keplinger, Franz; Jakoby, Bernhard

    2013-01-01

    Physical fluid parameters like viscosity, mass density and sound velocity can be determined utilizing ultrasonic sensors. We introduce the concept of a recently devised transmission based sensor utilizing pressure waves to determine the longitudinal viscosity, bulk viscosity, and second coefficient of viscosity of a sample fluid in a test chamber. A model is presented which allows determining these parameters from measurement values by means of a fit. The setup is particularly suited for liquids featuring higher viscosities for which measurement data are scarcely available to date. The setup can also be used to estimate the sound velocity in a simple manner from the phase of the transfer function. PMID:25844023

  8. Acoustic emission location on aluminum alloy structure by using FBG sensors and PSO method

    NASA Astrophysics Data System (ADS)

    Lu, Shizeng; Jiang, Mingshun; Sui, Qingmei; Dong, Huijun; Sai, Yaozhang; Jia, Lei

    2016-04-01

    Acoustic emission location is important for finding the structural crack and ensuring the structural safety. In this paper, an acoustic emission location method by using fiber Bragg grating (FBG) sensors and particle swarm optimization (PSO) algorithm were investigated. Four FBG sensors were used to form a sensing network to detect the acoustic emission signals. According to the signals, the quadrilateral array location equations were established. By analyzing the acoustic emission signal propagation characteristics, the solution of location equations was converted to an optimization problem. Thus, acoustic emission location can be achieved by using an improved PSO algorithm, which was realized by using the information fusion of multiple standards PSO, to solve the optimization problem. Finally, acoustic emission location system was established and verified on an aluminum alloy plate. The experimental results showed that the average location error was 0.010 m. This paper provided a reliable method for aluminum alloy structural acoustic emission location.

  9. Langasite surface acoustic wave gas sensors: modeling and verification

    SciTech Connect

    Peng Zheng,; Greve, D. W.; Oppenheim, I. J.

    2013-03-01

    We report finite element simulations of the effect of conductive sensing layers on the surface wave velocity of langasite substrates. The simulations include both the mechanical and electrical influences of the conducting sensing layer. We show that three-dimensional simulations are necessary because of the out-of-plane displacements of the commonly used (0, 138.5, 26.7) Euler angle. Measurements of the transducer input admittance in reflective delay-line devices yield a value for the electromechanical coupling coefficient that is in good agreement with the three-dimensional simulations on bare langasite substrate. The input admittance measurements also show evidence of excitation of an additional wave mode and excess loss due to the finger resistance. The results of these simulations and measurements will be useful in the design of surface acoustic wave gas sensors.

  10. Gas sensor technology at Sandia National Laboratories: Catalytic gate, Surface Acoustic Wave and Fiber Optic Devices

    SciTech Connect

    Hughes, R.C.; Moreno, D.J.; Jenkins, M.W.; Rodriguez, J.L.

    1993-10-01

    Sandia`s gas sensor program encompasses three separate electronic platforms: Acoustic Wave Devices, Fiber Optic Sensors and sensors based on silicon microelectronic devices. A review of most of these activities was presented recently in a article in Science under the title ``Chemical Microsensors.`` The focus of the program has been on understanding and developing the chemical sensor coatings that are necessary for using these electronic platforms as effective chemical sensors.

  11. Surface acoustic wave devices as passive buried sensors

    NASA Astrophysics Data System (ADS)

    Friedt, J.-M.; Rétornaz, T.; Alzuaga, S.; Baron, T.; Martin, G.; Laroche, T.; Ballandras, S.; Griselin, M.; Simonnet, J.-P.

    2011-02-01

    Surface acoustic wave (SAW) devices are currently used as passive remote-controlled sensors for measuring various physical quantities through a wireless link. Among the two main classes of designs—resonator and delay line—the former has the advantage of providing narrow-band spectrum informations and hence appears compatible with an interrogation strategy complying with Industry-Scientific-Medical regulations in radio-frequency (rf) bands centered around 434, 866, or 915 MHz. Delay-line based sensors require larger bandwidths as they consists of a few interdigitated electrodes excited by short rf pulses with large instantaneous energy and short response delays but is compatible with existing equipment such as ground penetrating radar (GPR). We here demonstrate the measurement of temperature using the two configurations, particularly for long term monitoring using sensors buried in soil. Although we have demonstrated long term stability and robustness of packaged resonators and signal to noise ratio compatible with the expected application, the interrogation range (maximum 80 cm) is insufficient for most geology or geophysical purposes. We then focus on the use of delay lines, as the corresponding interrogation method is similar to the one used by GPR which allows for rf penetration distances ranging from a few meters to tens of meters and which operates in the lower rf range, depending on soil water content, permittivity, and conductivity. Assuming propagation losses in a pure dielectric medium with negligible conductivity (snow or ice), an interrogation distance of about 40 m is predicted, which overcomes the observed limits met when using interrogation methods specifically developed for wireless SAW sensors, and could partly comply with the above-mentioned applications. Although quite optimistic, this estimate is consistent with the signal to noise ratio observed during an experimental demonstration of the interrogation of a delay line buried at a depth of 5

  12. An all fiber-optic sensor for surface acoustic wave measurements

    NASA Technical Reports Server (NTRS)

    Bowers, J. E.; Jungerman, R. L.; Khuri-Yakub, B. T.; Kino, G. S.

    1983-01-01

    A surface acoustic wave (SAW) sensor constructed from single-mode fiber-optic components is described. An analysis of reciprocal and nonreciprocal modes of operation of the sensor is presented. Results from measurements on a variety of SAW devices illustrate the use of the sensor. The amplitude sensitivity is 0.0003 A for an integration time of 0.1 s.

  13. Fish otolith mass asymmetry: morphometry and influence on acoustic functionality.

    PubMed

    Lychakov, D V; Rebane, Y T

    2005-03-01

    The role of the fish otolith mass asymmetry in acoustic functionality is studied. The saccular, lagenar and utricular otoliths are weighted in two species of the Black Sea rays, 15 species of the Black Sea teleost fish and guppy fish. The dimensionless otolith mass asymmetry chi is calculated as ratio of the difference between masses of the right and left paired otoliths to average otolith mass. In the most fish studied the otolith mass asymmetry is within the range of -0.2 < chi < +0.2 (< 20%). We do not find specific fish species with extremely large or extremely small otolith asymmetry. The large otoliths do not belong solely to any particular side, left or right. The heavier otoliths of different otolithic organs can be located in different labyrinths. No relationship has been found between the magnitude of the otolith mass asymmetry and the length (mass, age) of the animal. The suggested fluctuation model of the otolith growth can interpret these results. The model supposes that the otolith growth rate varies slightly hither and thither during lifetime of the individual fish. Therefore, the sign of the relative otolith mass asymmetry can change several times in the process of the individual fish growth but within the range outlined above. Mathematical modeling shows that acoustic functionality (sensitivity, temporal processing, sound localization) of the fish can be disturbed by the otolith mass asymmetry. But this is valid only for the fish with largest otolith masses, characteristic of the bottom and littoral fish, and with highest otolith asymmetry. For most fish the values of otolith mass asymmetry is well below critical values. Thus, the most fish get around the troubles related to the otolith mass asymmetry. We suggest that a specific physicochemical mechanism of the paired otolith growth that maintains the otolith mass asymmetry at the lowest possible level should exist. However, the principle and details of this mechanism are still far from being

  14. Starch viscoelastic properties studied with an acoustic wave sensor.

    PubMed

    Santos, M D; Gomes, M T S R

    2014-01-01

    Gelatinization and retrogradation of starch was followed in real time with an acoustic wave sensor. This study relies on the monitorization of the frequency of oscillation of a piezoelectric quartz crystal in contact with a 2.5% emulsion of a commercial maize starch, during heating and cooling. The technique showed to be very powerful and sensitive to most of the changes described in the literature, which have been elucidated by some other techniques. The value for the temperature of gelatinization found using the sensor was confirmed by the analysis of the same starch emulsion by polarized light microscopy. Temperatures of gelatinization were found to vary with the sample heating rate, as follows: 73.5 °C at 2.0 °C/min, 66.0 °C at 1.0 °C/min, and 65.0 °C at 0.5 °C/min. Hysteresis of the studied system was evidenced by the frequency shift before heating and after cooling till the initial temperature. Analysis performed on a 1.5% emulsion of a rice starch heated at 2.0 °C/min and cooled as before, evidenced no hysteresis and showed complete reversibility, in which concerns to the series frequency of the piezoelectric quartz crystal.

  15. Active structural acoustic control using the remote sensor method

    NASA Astrophysics Data System (ADS)

    Cheer, Jordan; Daley, Steve

    2016-09-01

    Active structural acoustic control (ASAC) is an effective method of reducing the sound radiation from vibrating structures. In order to implement ASAC systems using only structural actuators and sensors, it is necessary to employ a model of the sound radiation from the structure. Such models have been presented in the literature for simple structures, such as baffled rectangular plates, and methods of determining the radiation modes of more complex practical structures using experimental data have also been explored. A similar problem arises in the context of active noise control, where cancellation of a disturbance is required at positions in space where it is not possible to locate a physical error microphone. In this case the signals at the cancellation points can be estimated from the outputs of remotely located measurement sensors using the “remote microphone method”. This remote microphone method is extended here to the ASAC problem, in which the pressures at a number of microphone locations must be estimated from measurements on the structure of the radiating system. The control and estimation strategies are described and the performance is assessed for a typical structural radiation problem.

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

    NASA Astrophysics Data System (ADS)

    Trujillo, Blaine; Zagrai, Andrei

    2016-04-01

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

  17. Thick Films acoustic sensors devoted to MTR environment measurements. Thick Films acoustic sensors devoted to Material Testing Reactor environment measurements

    SciTech Connect

    Very, F.; Rosenkrantz, E.; Combette, P.; Ferrandis, J.Y.; Fourmentel, D.; Destouches, C.; Villard, J.F.

    2015-07-01

    The development of advanced instrumentation for in-pile experiments in Material Testing Reactor constitutes a main goal for the improvement of the nuclear fuel behavior knowledge. An acoustic method for fission gas release detection was tested with success during a first experiment called REMORA 3 in 2010 and 2011, and the results were used to differentiate helium and fission gas release kinetics under transient operating conditions. This experiment was lead at OSIRIS reactor (CEA Saclay, France). The maximal temperature on the sensor during the irradiation was about 150 deg. C. In this paper we present a thick film transducer produce by screen printing process. The screen printing of piezoelectric offers a wide range of possible applications for the development of acoustic sensors and piezoelectric structure for measurements in high temperature environment. We firstly produced a Lead Zirconate Titanate (PZT) based paste composed of Pz27 powder from Ferroperm, CF7575 glass, and organic solvent ESL 400. Likewise a Bismuth Titanate based paste synthesized in our laboratory was produced. With these inks we produced thick film up to 130 μm by screen printing process. Material properties characterizations of these thick-film resonators are essential for device design and applications. The piezoelectric coefficients d33 and pyro-electric P(T) coefficient are investigated. The highest P(T) and d33 are respectively 80 μC.m{sup -2}.K{sup -1} and 130 μC.N{sup -1} for the PZT transducer -which validates the fabrication process-. In view of the development of this transducer oriented for high temperature and irradiation environment, we investigated the electrical properties of the transducers for different ranges of frequencies and temperature - from 20 Hz up to 40 MHz between 30 and 400 deg. C. We highlight the evolution of the impedance response and piezoelectric parameters of screen printed piezoelectric structures on alumina. Shortly an irradiation will be realized in

  18. Identification of cavitation signatures using both optical and PZT acoustic sensors

    NASA Astrophysics Data System (ADS)

    Vidakovic, M.; Armakolas, I.; Sun, T.; Carlton, J.; Grattan, K. T. V.

    2015-09-01

    This paper presents the results obtained from monitoring a simulated material cavitation process using both a fibre Bragg grating (FBG)-based acoustic sensor system developed at City University London and a commercial PZT (Piezoelectric Transducer) acoustic sensor, with an aim to identify the cavitation signatures. In the experiment, a sample metal plate with its back surface being instrumented with both sensors is positioned very close to an excitation sonotrode with a standard frequency of 19.5kHz. The data obtained from both sensors are recorded and analyzed, showing a very good agreement.

  19. Investigation of acoustic sensors to detect coconut rhinoceros beetle in Guam

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The coconut rhinoceros beetle, Oryctes rhinoceros, was accidentally introduced into Guam last year and now threatens the Island’s forests and tourist industry. These large insects can be detected easily with acoustic sensors, and procedures are being developed to incorporate acoustic technology int...

  20. Local oscillator phase noise limitation on the resolution of acoustic delay line wireless passive sensor measurement

    NASA Astrophysics Data System (ADS)

    Chrétien, N.; Friedt, J.-M.; Martin, G.

    2014-06-01

    The role of the phase noise of a local oscillator driving a pulsed-mode RADAR used for probing surface acoustic wave sensors is investigated. The echo delay, representative of the acoustic velocity, and hence the physical quantity probed by the sensor, is finely measured as a phase. Considering that the intrinsic oscillator phase fluctuation defines the phase noise measurement resolution, we experimentally and theoretically assess the relation between phase noise, measurement range, and measurand resolution.

  1. Fiber Optic Sensor for Acoustic Detection of Partial Discharges in Oil-Paper Insulated Electrical Systems

    PubMed Central

    Posada-Roman, Julio; Garcia-Souto, Jose A.; Rubio-Serrano, Jesus

    2012-01-01

    A fiber optic interferometric sensor with an intrinsic transducer along a length of the fiber is presented for ultrasound measurements of the acoustic emission from partial discharges inside oil-filled power apparatus. The sensor is designed for high sensitivity measurements in a harsh electromagnetic field environment, with wide temperature changes and immersion in oil. It allows enough sensitivity for the application, for which the acoustic pressure is in the range of units of Pa at a frequency of 150 kHz. In addition, the accessibility to the sensing region is guaranteed by immune fiber-optic cables and the optical phase sensor output. The sensor design is a compact and rugged coil of fiber. In addition to a complete calibration, the in-situ results show that two types of partial discharges are measured through their acoustic emissions with the sensor immersed in oil. PMID:22666058

  2. Acoustic vector sensor beamforming reduces masking from underwater industrial noise during passive monitoring.

    PubMed

    Thode, Aaron M; Kim, Katherine H; Norman, Robert G; Blackwell, Susanna B; Greene, Charles R

    2016-04-01

    Masking from industrial noise can hamper the ability to detect marine mammal sounds near industrial operations, whenever conventional (pressure sensor) hydrophones are used for passive acoustic monitoring. Using data collected from an autonomous recorder with directional capabilities (Directional Autonomous Seafloor Acoustic Recorder), deployed 4.1 km from an arctic drilling site in 2012, the authors demonstrate how conventional beamforming on an acoustic vector sensor can be used to suppress noise arriving from a narrow sector of geographic azimuths. Improvements in signal-to-noise ratio of up to 15 dB are demonstrated on bowhead whale calls, which were otherwise undetectable using conventional hydrophones.

  3. 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.

  4. Evaluation on mass sensitivity of SAW sensors for different piezoelectric materials using finite-element analysis.

    PubMed

    Abdollahi, Amir; Jiang, Zhongwei; Arabshahi, Sayyed Alireza

    2007-12-01

    The mass sensitivity of the piezoelectric surface acoustic wave (SAW) sensors is an important factor in the selection of the best gravimetric sensors for different applications. To determine this value without facing the practical problems and the long theoretical calculation time, we have shown that the mass sensitivity of SAW sensors can be calculated by a simple three-dimensional (3-D) finite-element analysis (FEA) using a commercial finite-element platform. The FEA data are used to calculate the wave propagation speed, surface particle displacements, and wave energy distribution on different cuts of various piezoelectric materials. The results are used to provide a simple method for evaluation of their mass sensitivities. Meanwhile, to calculate more accurate results from FEA data, surface and bulk wave reflection problems are considered in the analyses. In this research, different cuts of lithium niobate, quartz, lithium tantalate, and langasite piezoelectric materials are applied to investigate their acoustic wave properties. Our analyses results for these materials have a good agreement with other researchers' results. Also, the mass sensitivity value for the novel cut of langasite was calculated through these analyses. It was found that its mass sensitivity is higher than that of the conventional Rayleigh mode quartz sensor.

  5. Electro-acoustic sensors based on AlN thin film: possibilities and limitations

    NASA Astrophysics Data System (ADS)

    Wingqvist, Gunilla

    2011-06-01

    The non-ferroelectric polar wurtzite aluminium nitride (AlN) material has been shown to have potential for various sensor applications both utilizing the piezoelectric effect directly for pressure sensors or indirectly for acoustic sensing of various physical, chemical and biochemical sensor applications. Especially, sputter deposited AlN thin films have played a central role for successful development of the thin film electro-acoustic technology. The development has been primarily driven by one device - the thin film bulk acoustic resonator (FBAR or TFBAR), with its primary use for high frequency filter applications for the telecom industry. AlN has been the dominating choice for commercial application due to compatibility with the integrated circuit technology, low acoustic and dielectric losses, high acoustic velocity in combination with comparably high (but still for some applications limited) electromechanical coupling. Recently, increased piezoelectric properties (and also electromechanical coupling) in the AlN through the alloying with scandium nitride (ScN) have been identified both experimentally and theoretically. Inhere, the utilization of piezoelectricity in electro-acoustic sensing will be discussed together with expectation on acoustic FBAR sensor performance with variation in piezoelectric material properties in the parameter space around AlN due to alloying, in view of the ScxAl1-xN (0

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

    DOEpatents

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

    1998-08-18

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

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

    DOEpatents

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

    1998-01-01

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

  8. Quantitative determination of protein molecular weight with an acoustic sensor; significance of specific versus non-specific binding.

    PubMed

    Mitsakakis, Konstantinos; Tsortos, Achilleas; Gizeli, Electra

    2014-08-21

    Surface acoustic wave sensors with integrated microfluidics for multi-sample sensing have been implemented in this work towards the quantitative correlation of the acoustic signal with the molecular weight of surface bound proteins investigating different interaction/binding conditions. The results are presented for: (i) four different biotinylated molecules (30 ≤ Mw ≤ 150 kDa) specifically binding to neutravidin; (ii) the same four non-biotinylated molecules, as well as neutravidin, adsorbing onto gold; and (iii) four cardiac marker proteins (86 ≤ Mw ≤ 540 kDa) specifically binding to their homologous antibodies. Surface plasmon resonance was employed as an independent optical mass sensor. A linear relationship was found to exist between the phase change of the acoustic signal and the molecular weight of the proteins in both cases of specific binding. In contrast, non-specific binding of proteins directly onto gold exhibited no such linear relationship. In all three cases phase change was correlated with the bound mass per area. The underlying mechanism behind the different behavior between specific and non-specific binding is discussed by taking into account the geometrical restrictions imposed by the size of the specific biorecognition molecule and the corresponding bound protein. Our results emphasize the quantitative nature of the phase of the acoustic signal in determining the Mw (in the case of specific binding) with a resolution of 15% and the mass of the bound proteins (in all cases), as well as the significance of the biorecognition molecules in deriving the molecular weight from acoustic or optical detectors.

  9. High-frequency, high-sensitivity acoustic sensor implemented on ALN/Si substrate

    NASA Astrophysics Data System (ADS)

    Caliendo, C.; Imperatori, P.

    2003-08-01

    AlN films, 1.6-6.3 μm thick, were sputtered at 200 °C on Si(100) and Si(111) substrates. The films were crack-free, uniform, and c-axis oriented. The experimental phase velocities of surface acoustic waves (SAW) propagating in the AlN/Si structures were estimated and showed only a small discrepancy (20-40 m/s) compared to the calculated theoretical values. A SAW resonator (SAWR)-based chemical sensor, operating at about 700 MHz, was implemented on AlN/Si. The SAWR surface was covered with a polymer film sensitive to relative humidity (RH) changes, already tested for RH sensing in previous works on SAW delay lines implemented on AlN/Si and ZnO/Si and operating at about 130 MHz. The RH mass sensitivity and the detection limit of the SAWR sensor improved by 38% and by one order of magnitude, respectively, compared to the delay line-based sensors previously tested.

  10. Membrane-type acoustic metamaterial with negative dynamic mass.

    PubMed

    Yang, Z; Mei, Jun; Yang, Min; Chan, N H; Sheng, Ping

    2008-11-14

    We present the experimental realization and theoretical understanding of a membrane-type acoustic metamaterial with very simple construct, capable of breaking the mass density law of sound attenuation in the 100-1000 Hz regime by a significant margin ( approximately 200 times). Owing to the membrane's weak elastic moduli, there can be low-frequency oscillation patterns even in a small elastic film with fixed boundaries defined by a rigid grid. The vibrational eigenfrequencies can be tuned by placing a small mass at the center of the membrane sample. Near-total reflection is achieved at a frequency between two eigenmodes where the in-plane average of normal displacement is zero. By using finite element simulations, negative dynamic mass is explicitly demonstrated at frequencies around the total reflection frequency. Excellent agreement between theory and experiment is obtained.

  11. Sensitivity of optical mass sensor enhanced by optomechanical coupling

    SciTech Connect

    He, Yong

    2015-03-23

    Optical mass sensors based on cavity optomechanics employ radiation pressure force to drive mechanical resonator whose mechanical susceptibility can be described by nonlinear optical transmission spectrum. In this paper, we present an optical mass sensor based on a two-cavity optomechanical system where the mechanical damping rate can be decreased by adjusting a pump power so that the mass sensitivity which depends on the mechanical quality factor has been enhanced greatly. Compared with that of an optical mass sensor based on single-cavity optomechanics, the mass sensitivity of the optical mass sensor is improved by three orders of magnitude. This is an approach to enhance the mass sensitivity by means of optomechanical coupling, which is suitable for all mass sensor based on cavity optomechanics. Finally, we illustrate the accurate measurement for the mass of a few chromosomes, which can be achieved based on the current experimental conditions.

  12. Sensitivity of optical mass sensor enhanced by optomechanical coupling

    NASA Astrophysics Data System (ADS)

    He, Yong

    2015-03-01

    Optical mass sensors based on cavity optomechanics employ radiation pressure force to drive mechanical resonator whose mechanical susceptibility can be described by nonlinear optical transmission spectrum. In this paper, we present an optical mass sensor based on a two-cavity optomechanical system where the mechanical damping rate can be decreased by adjusting a pump power so that the mass sensitivity which depends on the mechanical quality factor has been enhanced greatly. Compared with that of an optical mass sensor based on single-cavity optomechanics, the mass sensitivity of the optical mass sensor is improved by three orders of magnitude. This is an approach to enhance the mass sensitivity by means of optomechanical coupling, which is suitable for all mass sensor based on cavity optomechanics. Finally, we illustrate the accurate measurement for the mass of a few chromosomes, which can be achieved based on the current experimental conditions.

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

    PubMed

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

    2011-09-01

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

  14. Mass flow sensor utilizing a resistance bridge

    NASA Technical Reports Server (NTRS)

    Fralick, Gustave C. (Inventor); Hwang, Danny P. (Inventor); Wrbanek, John D. (Inventor)

    2004-01-01

    A mass flow sensor to be mounted within a duct and measures the mass flow of a fluid stream moving through the duct. The sensor is an elongated thin quartz substrate having a plurality of platinum strips extending in a parallel relationship on the strip, with certain of the strips being resistors connected to an excitation voltage. The resistors form the legs of a Wheatstone bridge. The resistors are spaced a sufficient distance inwardly from the leading and trailing edges of the substrate to lie within the velocity recovery region so that the measured flow is the same as the actual upstream flow. The resistor strips extend at least half-way through the fluid stream to include a substantial part of the velocity profile of the stream. Certain of the resistors detect a change in temperature as the fluid stream moves across the substrate to provide an output signal from the Wheatstone bridge which is representative of the fluid flow. A heater is located in the midst of the resistor array to heat the air as it passes over the array.

  15. Multi Reflection of Lamb Wave Emission in an Acoustic Waveguide Sensor

    PubMed Central

    Schmitt, Martin; Olfert, Sergei; Rautenberg, Jens; Lindner, Gerhard; Henning, Bernd; Reindl, Leonhard Michael

    2013-01-01

    Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid—liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualized by Schlieren imaging for continuous and burst operation the first time. In the acoustic waveguide the antisymmetrical zero order Lamb wave mode is excited by a single phase transducer of 1 MHz on thin glass plates of 1 mm thickness. By contact to the investigated liquid Lamb waves propagating on the first plate emit pressure waves into the adjacent liquid, which excites Lamb waves on the second plate, what again causes pressure waves traveling inside the liquid back to the first plate and so on. The Schlieren images prove this multi reflection within the acoustic waveguide, which confirms former considerations and calculations based on the receiver signal. With this knowledge the sensor concepts with the acoustic waveguide sensor can be interpreted in a better manner. PMID:23447010

  16. Multi reflection of Lamb wave emission in an acoustic waveguide sensor.

    PubMed

    Schmitt, Martin; Olfert, Sergei; Rautenberg, Jens; Lindner, Gerhard; Henning, Bernd; Reindl, Leonhard Michael

    2013-02-27

    Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid-liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualized by Schlieren imaging for continuous and burst operation the first time. In the acoustic waveguide the antisymmetrical zero order Lamb wave mode is excited by a single phase transducer of 1 MHz on thin glass plates of 1 mm thickness. By contact to the investigated liquid Lamb waves propagating on the first plate emit pressure waves into the adjacent liquid, which excites Lamb waves on the second plate, what again causes pressure waves traveling inside the liquid back to the first plate and so on. The Schlieren images prove this multi reflection within the acoustic waveguide, which confirms former considerations and calculations based on the receiver signal. With this knowledge the sensor concepts with the acoustic waveguide sensor can be interpreted in a better manner.

  17. Surface properties of solids and surface acoustic waves: Application to chemical sensors and layer characterization

    NASA Astrophysics Data System (ADS)

    Krylov, V. V.

    1995-09-01

    A general phenomenological approach is given for the description of mechanical surface properties of solids and their influence on surface acoustic wave propogation. Surface properties under consideration may be changes of the stress distribution in subsurface atomic layers, the presence of adsorbed gas molecules, surface degradation as a result of impacts from an aggressive environment, damage due to mechanical manufacturing or polishing, deposition of thin films or liquid layers, surface corrugations, etc. If the characteristic thickness of the affected layers is much less than the wavelengths of the propagating surface waves, then the effects of all these irregularities can be described by means of non-classical boundary conditions incorporating the integral surface parameters such as surface tension, surface moduli of elasticity and surface mass density. The effect of surface properties on the propagation of Rayleigh surface waves is analysed in comparison with the results of traditional approaches, in particular with Auld's energy perturbation method. One of the important implications of the above-mentioned boudnary conditions is that they are adequate for the description of the effect of rarely distributed adsorbed atoms or molecules. This allows, in particular, to obtain a rigorous theoretical description of chemical sensors using surface acoustic waves and to derive analytical expressions for their sensitivity.

  18. Ion acoustic shock wave in collisional equal mass plasma

    SciTech Connect

    Adak, Ashish; Ghosh, Samiran; Chakrabarti, Nikhil

    2015-10-15

    The effect of ion-ion collision on the dynamics of nonlinear ion acoustic wave in an unmagnetized pair-ion plasma has been investigated. The two-fluid model has been used to describe the dynamics of both positive and negative ions with equal masses. It is well known that in the dynamics of the weakly nonlinear wave, the viscosity mediates wave dissipation in presence of weak nonlinearity and dispersion. This dissipation is responsible for the shock structures in pair-ion plasma. Here, it has been shown that the ion-ion collision in presence of collective phenomena mediated by the plasma current is the source of dissipation that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The dynamics of the weakly nonlinear wave is governed by the Korteweg-de Vries Burgers equation. The analytical and numerical investigations revealed that the ion acoustic wave exhibits both oscillatory and monotonic shock structures depending on the frequency of ion-ion collision parameter. The results have been discussed in the context of the fullerene pair-ion plasma experiments.

  19. Acoustic metamaterial with negative mass density in water

    SciTech Connect

    Chen, Huaijun; Zhai, Shilong; Ding, Changlin; Luo, Chunrong; Zhao, Xiaopeng

    2015-09-07

    A two-dimensional (2D) acoustic metamaterial (AM) with negative effective mass density in water is designed by periodically arranging hollow tube “meta-atoms.” Experimental and simulated results demonstrate that transmission dips accompanied with inverse phases are presented in the transmission spectra of the 2D AM at the ultrasonic frequency band. Effective parameters extracted from the experimental measured transmission and reflection coefficients of the 2D AM show that the effective mass density and refractive index are negative near the dip frequency range of 35.31–35.94 kHz. The simulation also shows the negative response in the 2D AM. Due to the excellent properties, the 2D AM is appealing for the potential applications in areas such as subwavelength imaging, ultrasonic cloaking in water, and so on.

  20. Surface acoustic-wave piezoelectric crystal aerosol mass microbalance

    NASA Astrophysics Data System (ADS)

    Bowers, W. D.; Chuan, R. L.

    1989-07-01

    The development of a particulate mass-sensing instrument based on a quartz-crystal microbalance and enhanced with the new surface acoustic-wave (SAW) technology is reported. Mass sensitivity comparisons of a 158-MHz SAW piezoelectric microbalance and a conventional 10-MHz quartz-crystal microbalance show that the SAW crystal is 266 times more sensitive, in good agreement with the theoretical value of 250. The frequency stability of a single SAW resonator is 6 parts in 10 to the 8th over 1 min. The response to temperature changes is found to be very linear over the range +30 to -30 C. A strong response to 15 ppm SO2 has been demonstrated on a chemically coated SAW crystal.

  1. The near-field acoustic levitation of high-mass rotors.

    PubMed

    Hong, Z Y; Lü, P; Geng, D L; Zhai, W; Yan, N; Wei, B

    2014-10-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  2. The near-field acoustic levitation of high-mass rotors

    SciTech Connect

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B.

    2014-10-15

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  3. Improving the sensitivity of an interferometric fiber optic sensor for acoustic detection in rockfalls

    NASA Astrophysics Data System (ADS)

    Schenato, L.; Palmieri, L.; Autizi, E.; Galtarossa, A.; Pasuto, A.

    2013-12-01

    Being intrinsically EMI free and offering superior hostile environment operation, fiber optic sensor technology represents a valuable alternative to standard sensors technology in landslides monitoring. Here an improved design for a fiber optic sensor to be used for ultrasonic acoustic detection in rockfall monitoring is proposed. Basically, the original sensor consists of a fiber coil tightly wound on an aluminum flanged hollow mandrel that acts as the sensing arm of a Mach-Zehnder interferometer [1]. To further improve sensor sensitivity, the use of a special fiber, with polyimide coating and very large numerical aperture, has been proposed and tested. The polyimide coating, harder and thinner than standard coating, makes the fiber more sensitive to acoustic waves and increase the coupling efficiency between fiber and mandrel. At the same time, a fiber with very large numerical aperture allows for a much smaller bending radius and thus enables the design of a sensor with reduced size, or with the same external size but housing a longer fiber. Part of the research activity has been then focused toward the optimization of the shape and dimensions of the mandrel: to this aim, a large set of numerical simulations has been performed and they are here presented and discussed. The performance assessment gained with new sensors has been carried in a controlled scenario by using a block of trachyte in which the sensors have been screwed in internally threaded chemical anchors housed in holes drilled on one face of the block. Ultrasonic signals have been generated in a repeatable way by dropping a 5-mm-diameter steel ball along a steep slide. Experimental tests, carried out by firstly comparing the performance of a sensor made with special fiber with respect to the original one, have shown an increased sensitivity of almost 35 % in the detected acoustic energy. Further tests, carried out on a sensor with optimized dimensions and made with special fiber, have shown an

  4. Embedded Acoustic Sensor Array for Engine Fan Noise Source Diagnostic Test: Feasibility of Noise Telemetry via Wireless Smart Sensors

    NASA Technical Reports Server (NTRS)

    Zaman, Afroz; Bauch, Matthew; Raible, Daniel

    2011-01-01

    Aircraft engines have evolved into a highly complex system to meet ever-increasing demands. The evolution of engine technologies has primarily been driven by fuel efficiency, reliability, as well as engine noise concerns. One of the sources of engine noise is pressure fluctuations that are induced on the stator vanes. These local pressure fluctuations, once produced, propagate and coalesce with the pressure waves originating elsewhere on the stator to form a spinning pressure pattern. Depending on the duct geometry, air flow, and frequency of fluctuations, these spinning pressure patterns are self-sustaining and result in noise which eventually radiate to the far-field from engine. To investigate the nature of vane pressure fluctuations and the resulting engine noise, unsteady pressure signatures from an array of embedded acoustic sensors are recorded as a part of vane noise source diagnostics. Output time signatures from these sensors are routed to a control and data processing station adding complexity to the system and cable loss to the measured signal. "Smart" wireless sensors have data processing capability at the sensor locations which further increases the potential of wireless sensors. Smart sensors can process measured data locally and transmit only the important information through wireless communication. The aim of this wireless noise telemetry task was to demonstrate a single acoustic sensor wireless link for unsteady pressure measurement, and thus, establish the feasibility of distributed smart sensors scheme for aircraft engine vane surface unsteady pressure data transmission and characterization.

  5. Study on high temperature Fabry-Perot fiber acoustic sensor with temperature self-compensation

    NASA Astrophysics Data System (ADS)

    Hu, Pan; Tong, Xinglin; Zhao, Minli; Deng, Chengwei; Guo, Qian; Mao, Yan; Wang, Kun

    2015-09-01

    A Fabry-Perot (F-P) fiber acoustic sensor, which can work under high-temperature harsh environment with temperature self-compensation, is designed and prepared. A condenser was used to maintain the sensor to work in a stable temperature environment. Because of the special structure of the sensor and the function of the condenser, the cavity variation of the sensor caused by changes of external temperature from -10°C to 500°C would not exceed 8 nm. The experimental results show that the sensor has a good frequency response in a range of 1 to 5 kHz and the field experiment results show that it could be used for hydraulic decoking online monitoring by judging the acoustic frequency spectrum.

  6. Spectrum interrogation of fiber acoustic sensor based on self-fitting and differential method.

    PubMed

    Fu, Xin; Lu, Ping; Ni, Wenjun; Liao, Hao; Wang, Shun; Liu, Deming; Zhang, Jiangshan

    2017-02-20

    In this article, we propose an interrogation method of fiber acoustic sensor to recover the time-domain signal from the sensor spectrum. The optical spectrum of the sensor will show a ripple waveform when responding to acoustic signal due to the scanning process in a certain wavelength range. The reason behind this phenomenon is the dynamic variation of the sensor spectrum while the intensity of different wavelength is acquired at different time in a scanning period. The frequency components can be extracted from the ripple spectrum assisted by the wavelength scanning speed. The signal is able to be recovered by differential between the ripple spectrum and its self-fitted curve. The differential process can eliminate the interference caused by environmental perturbations such as temperature or refractive index (RI), etc. The proposed method is appropriate for fiber acoustic sensors based on gratings or interferometers. A long period grating (LPG) is adopted as an acoustic sensor head to prove the feasibility of the interrogation method in experiment. The ability to compensate the environmental fluctuations is also demonstrated.

  7. Detection of third-hand smoke on clothing fibers with a surface acoustic wave gas sensor

    PubMed Central

    Cheng, Chi-Yung; Huang, Shih-Shen; Yang, Chia-Min; Tang, Kea-Tiong

    2016-01-01

    Third-hand smoke (THS) is a new cigarette-related issue defined as the residual contamination from cigarette smoke after a cigarette is extinguished. To detect THS on three commonly used clothing fibers—wool, cotton, and polyester, we applied two methods to measure the adsorption of THS: one was the gain of mass with an analytical balance after exposure to cigarette smoke; and the other was to detect the THS chemical compounds such as nicotine and 3-ethenylpyridine with a surface acoustic wave (SAW) sensor composed of coated oxidized hollow mesoporous carbon nanospheres. In the mass measurement, the gain of mass decreased in the order wool, cotton, and polyester; the latter gain was about one tenth that of wool. In the SAW detection, the frequency shift decreased in the same order—wool, cotton, and polyester. The residence period of THS on natural fiber (wool and cotton) is greater than on synthetic polyester fiber. These two tests provide quantitative results of THS on varied clothing fibers, to assess their risk after exposure to cigarette smoke. PMID:26909119

  8. New Research on MEMS Acoustic Vector Sensors Used in Pipeline Ground Markers

    PubMed Central

    Song, Xiaopeng; Jian, Zeming; Zhang, Guojun; Liu, Mengran; Guo, Nan; Zhang, Wendong

    2015-01-01

    According to the demands of current pipeline detection systems, the above-ground marker (AGM) system based on sound detection principle has been a major development trend in pipeline technology. A novel MEMS acoustic vector sensor for AGM systems which has advantages of high sensitivity, high signal-to-noise ratio (SNR), and good low frequency performance has been put forward. Firstly, it is presented that the frequency of the detected sound signal is concentrated in a lower frequency range, and the sound attenuation is relatively low in soil. Secondly, the MEMS acoustic vector sensor structure and basic principles are introduced. Finally, experimental tests are conducted and the results show that in the range of 0°∼90°, when r = 5 m, the proposed MEMS acoustic vector sensor can effectively detect sound signals in soil. The measurement errors of all angles are less than 5°. PMID:25609046

  9. Acoustic emission monitoring of structural perturbations with serially multiplexed optical fiber sensors

    NASA Astrophysics Data System (ADS)

    Liang, Yujin; Sun, Changsen; Ansari, Farhad

    2005-05-01

    Damage location and damage state identification of a hybrid Carbon-glass FRP rod was performed by means of a serially multiplexed fiber optic acoustic emission sensor. The detection and identification of acoustic emission signals along a single data stream reduces the data acquisition rigor and provides for rapid real time damage location detection in materials. Linear source location method and signature frequency spectra energy of acoustic emission signals were employed for locating the fiber breakage and distinguishing the damage state in the hybrid FRP rod, respectively.

  10. Modal structural acoustic sensing with minimum number of optimally placed piezoelectric sensors

    NASA Astrophysics Data System (ADS)

    Loghmani, Ali; Danesh, Mohammad; Keshmiri, Mehdi

    2016-02-01

    Structural acoustic sensing is a method of obtaining radiated sound pressure from a vibrating structure using vibration information. Structural acoustic sensing is used in active structural acoustic control for attenuating the sound radiated from a structure. In this paper, a new approach called Modal Structural Acoustic Sensing (MSAS) is proposed for estimating the pressure radiated from a vibrating cylindrical shell using piezoelectric sensors. The motion equations of a cylindrical shell in conjunction with piezoelectric patches are derived based on the Donnel-Mushtari shell theory. The locations of the piezoelectric sensors are optimized by the Genetic Algorithm based on maximizing the observability gramian matrix. The Kirchhoff-Helmholtz integral is used for estimating the sound pressure radiated from the cylindrical shell. Numerical simulations are performed to demonstrate the advantages of the proposed approach in comparison with previous methods such as discrete structural acoustic sensing and distributed modal sensors. Results show that the MSAS can increase the estimation accuracy and decrease the controller dimensionality and the number of required sensors.

  11. Fiber-optic intrinsic distributed acoustic emission sensor for large structure health monitoring.

    PubMed

    Liang, Sheng; Zhang, Chunxi; Lin, Wentai; Li, Lijing; Li, Chen; Feng, Xiujuan; Lin, Bo

    2009-06-15

    A fiber-optic intrinsic distributed acoustic emission (AE) sensor is proposed. By measuring the time delay of two signals from two Mach-Zehnder interferometers, the location of AE can be deduced, and the corresponding sensor is experimentally verified to be feasible with a 206 m average location error in a 20 km sensing range, which shows that this proposed sensor is applicable for distributed AE sensing for large structure health monitoring, with the unique advantages of low cost, simple configuration, and long sensing range. The limitations of the proposed sensor are also discussed, and the future work is presented.

  12. The Biological Sensor for Detection of Bacterial Cells in Liquid Phase Based on Plate Acoustic Wave

    NASA Astrophysics Data System (ADS)

    Borodina, Irina; Zaitsev, Boris; Shikhabudinov, Alexander; Guliy, Olga; Ignatov, Oleg; Teplykh, Andrey

    The interactions "bacterial cells - bacteriophages", "bacterial cells - antibodies" and "bacterial cells - mini- antibodies" directly in liquid phase were experimentally investigated with a help of acoustic sensor. The acoustic sensor under study represents two-channel delay line based on the plate of Y-X lithium niobate. One channel of delay line was electrically shorted, the second channel was electrically open. The liquid container was glued on plate surface between transducers of delay line. The dependencies of the change in phase and insertion loss on concentration of bacteriophages, antibodies, and mini- antibodies were obtained for both channels of delay line.

  13. Biotin-streptavidin binding interactions of dielectric filled silicon bulk acoustic resonators for smart label-free biochemical sensor applications.

    PubMed

    Heidari, Amir; Yoon, Yong-Jin; Park, Woo-Tae; Su, Pei-Chen; Miao, Jianmin; Lin, Julius Tsai Ming; Park, Mi Kyoung

    2014-03-07

    Sensor performance of a dielectric filled silicon bulk acoustic resonator type label-free biosensor is verified with biotin-streptavidin binding interactions as a model system. The mass sensor is a micromachined silicon square plate with a dielectric filled capacitive excitation mechanism. The resonance frequency of the biotin modified resonator decreased 315 ppm when exposed to streptavidin solution for 15 min with a concentration of 10(-7) M, corresponding to an added mass of 3.43 ng on the resonator surface. An additional control is added by exposing a bovine serum albumin (BSA)-covered device to streptavidin in the absence of the attached biotin. No resonance frequency shift was observed in the control experiment, which confirms the specificity of the detection. The sensor-to-sensor variability is also measured to be 4.3%. Consequently, the developed sensor can be used to observe in biotin-streptavidin interaction without the use of labelling or molecular tags. In addition, biosensor can be used in a variety of different immunoassay tests.

  14. Biotin-Streptavidin Binding Interactions of Dielectric Filled Silicon Bulk Acoustic Resonators for Smart Label-Free Biochemical Sensor Applications

    PubMed Central

    Heidari, Amir; Yoon, Yong-Jin; Park, Woo-Tae; Su, Pei-Chen; Miao, Jianmin; Lin, Julius Tsai Ming; Park, Mi Kyoung

    2014-01-01

    Sensor performance of a dielectric filled silicon bulk acoustic resonator type label-free biosensor is verified with biotin-streptavidin binding interactions as a model system. The mass sensor is a micromachined silicon square plate with a dielectric filled capacitive excitation mechanism. The resonance frequency of the biotin modified resonator decreased 315 ppm when exposed to streptavidin solution for 15 min with a concentration of 10−7 M, corresponding to an added mass of 3.43 ng on the resonator surface. An additional control is added by exposing a bovine serum albumin (BSA)-covered device to streptavidin in the absence of the attached biotin. No resonance frequency shift was observed in the control experiment, which confirms the specificity of the detection. The sensor-to-sensor variability is also measured to be 4.3%. Consequently, the developed sensor can be used to observe in biotin-streptavidin interaction without the use of labelling or molecular tags. In addition, biosensor can be used in a variety of different immunoassay tests. PMID:24608003

  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. Measurement of Plasma Clotting Using Shear Horizontal Surface Acoustic Wave Sensor

    NASA Astrophysics Data System (ADS)

    Nagayama, Tatsuya; Kondoh, Jun; Oonishi, Tomoko; Hosokawa, Kazuya

    2013-07-01

    The monitoring of blood coagulation is important during operation. In this study, a shear horizontal surface acoustic wave (SH-SAW) sensor is applied to monitor plasma clotting. An SH-SAW sensor with a metallized surface for mechanical perturbation detection can detect plasma clotting. As plasma clotting is a gel formation reaction, the SH-SAW sensor detects viscoelastic property changes. On the other hand, an SH-SAW sensor with a free surface for electrical perturbation detection detects only the liquid mixing effect. No electrical property changes due to plasma clotting are obtained using this sensor. A planar electrochemical sensor is also used to monitor plasma clotting. In impedance spectral analysis, plasma clotting is measured. However, in the measurement of time responses, no differences between clotting and nonclotting are obtained. Therefore, the SH-SAW sensor is useful for monitoring plasma clotting.

  17. Acoustic sensor for monitoring adhesion of Neuro-2A cells in real-time.

    PubMed

    Khraiche, Massoud Louis; Zhou, Anhong; Muthuswamy, Jit

    2005-05-15

    Neuronal adhesion plays a fundamental role in growth, migration, regeneration and plasticity of neurons. However, current methods for studying neuronal adhesion cannot monitor this phenomenon quantitatively in real-time. In this work, we demonstrate the use of an acoustic sensor to measure adhesion of neuro-blastoma cells (Neuro-2A) in real-time. An acoustic sensor consisting of a quartz crystal sandwiched between gold electrodes was placed in a flow cell and filled with 600 microl of phosphate buffered saline (PBS). Two sets of in vitro experiments were performed using sensors that had uncoated gold electrodes and sensors that were coated with a known neuronal adhesion promoter (poly-l-lysine or PLL). The instantaneous resonant frequency and the equivalent motional resistance of the acoustic sensor were monitored every second. Cell Tracker was used to confirm neuronal adhesion to the surface. Addition of 10 microl of media and Neuro-2A cells into the above set-up elicited exponential changes in the resonant frequency and motional resistance of the quartz crystal with time to reach steady state in the range of 2-11 h. The steady-state change in resonant frequency in response to addition of neurons was linearly related to the number of Neuro-2A cells added (R2=0.94). Acoustic sensors coated with the adhesion promoter, PLL showed a much higher change in resonant frequency for approximately the same number of neurons. We conclude that the acoustic sensor has sufficient sensitivity to monitor neuronal adhesion in real-time. This has potential applications in the study of mechanisms of neuron-substrate interactions and the effect of molecular modulators in the extra cellular matrix.

  18. Fiber-optic photo-acoustic spectroscopy sensor for harsh environment gas detection

    NASA Astrophysics Data System (ADS)

    Wu, Juntao; Deng, Kung-Li; Guida, Renato; Lee, Boon

    2007-09-01

    Photo-acoustic spectroscopy (PAS) has been successfully applied to detect various gases and chemicals due to its high selectivity and sensitivity. However, the performance of the conventional acoustic sensors prohibits the application of PAS for harsh environment gas species real-time monitoring. By replacing conventional acoustic sensors, such as microphone and piezo-transducers, with a high-temperature Fiber Bragg Grating (FBG) vibration sensor, we developed a fiber-optic PAS sensing system that can be used in high-temperature and high-pressure harsh environments for gas species identification and concentration measurement. A resonant acoustic chamber is designed, and FBG vibration sensor is embedded in the molybdenum membrane. An OPO laser is used for spectrum scanning. Preliminary test on water vapor has been conducted, and the result is analyzed. This sensing technology can be adapted into harsh environments, such as Integrated Gasification Combined Cycle (IGCC) power plant, and provide on-line real-time monitoring of gases species, such as CO, H IIO, and O II. Presently, our FBG-based vibration sensor can withstand the high temperature up to 800°C.

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

    DOE PAGES

    Kral, Zachary; Horn, Walter; Steck, James

    2013-01-01

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

  20. Vehicle acoustic classification in netted sensor systems using Gaussian mixture models

    NASA Astrophysics Data System (ADS)

    Necioglu, Burhan F.; Christou, Carol T.; George, E. B.; Jacyna, Garry M.

    2005-05-01

    Acoustic vehicle classification is a difficult problem due to the non-stationary nature of the signals, and especially the lack of strong harmonic structure for most civilian vehicles with highly muffled exhausts. Acoustic signatures will also vary largely depending on speed, acceleration, gear position, and even the aspect angle of the sensor. The problem becomes more complicated when the deployed acoustic sensors have less than ideal characteristics, in terms of both the frequency response of the transducers, and hardware capabilities which determine the resolution and dynamic range. In a hierarchical network topology, less capable Tier 1 sensors can be tasked with reasonably sophisticated signal processing and classification algorithms, reducing energy-expensive communications with the upper layers. However, at Tier 2, more sophisticated classification algorithms exceeding the Tier 1 sensor/processor capabilities can be deployed. The focus of this paper is the investigation of a Gaussian mixture model (GMM) based classification approach for these upper nodes. The use of GMMs is motivated by their ability to model arbitrary distributions, which is very relevant in the case of motor vehicles with varying operation modes and engines. Tier 1 sensors acquire the acoustic signal and transmit computed feature vectors up to Tier 2 processors for maximum-likelihood classification using GMMs. In a binary classification task of light-vs-heavy vehicles, the GMM based approach achieves 7% equal error rate, providing an approximate error reduction of 49% over Tier 1 only approaches.

  1. 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.

  2. Mass sensitivity of layered shear-horizontal surface acoustic wave devices for sensing applications

    NASA Astrophysics Data System (ADS)

    Kalantar-Zadeh, Kourosh; Trinchi, Adrian; Wlodarski, Wojtek; Holland, Anthony; Galatsis, Kosmas

    2001-11-01

    Layered Surface Acoustic Wave (SAW) devices that allow the propagation of Love mode acoustic waves will be studied in this paper. In these devices, the substrate allows the propagation of Surface Skimming Bulks Waves (SSBWs). By depositing layers, that the speed of Shear Horizontal (SH) acoustic wave propagation is less than that of the substrate, the propagation mode transforms to Love mode. Love mode devices which will be studied in this paper, have SiO2 and ZnO acoustic guiding layers. As Love mode of propagation has no movement of particles component normal to the active sensor surface, they can be employed for the sensing applications in the liquid media.

  3. 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

    2012-08-07

    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.

  4. A high sensitivity wireless mass-loading surface acoustic wave DNA biosensor

    NASA Astrophysics Data System (ADS)

    Cai, Hua-Lin; Yang, Yi; Zhang, Yi-Han; Zhou, Chang-Jian; Guo, Cang-Ran; Liu, Jing; Ren, Tian-Ling

    2014-03-01

    In this paper, a surface acoustic wave (SAW) biosensor with gold delay area on LiNbO3 substrate detecting DNA sequences is proposed. By well-designed device parameters of the SAW sensor, it achieves a high performance for highly sensitive detection of target DNA. In addition, an effective biological treatment method for DNA immobilization and abundant experimental verification of the sensing effect have made it a reliable device in DNA detection. The loading mass of the probe and target DNA sequences is obtained from the frequency shifts, which are big enough in this work due to an effective biological treatment. The experimental results show that the biosensor has a high sensitivity of 1.2 pg/ml/Hz and high selectivity characteristic is also verified by the few responses of other substances. In combination with wireless transceiver, we develop a wireless receiving and processing system that can directly display the detection results.

  5. Inverse least-squares modeling of vapor descriptors using polymer-coated surface acoustic wave sensor array responses.

    PubMed

    Grate, J W; Patrash, S J; Kaganovet, S N; Abraham, M H; Wise, B M; Gallagher, N B

    2001-11-01

    In previous work, it was shown that, in principle, vapor descriptors could be derived from the responses of an array of polymer-coated acoustic wave devices. This new chemometric classification approach was based on polymer/vapor interactions following the well-established linear solvation energy relationships (LSERs) and the surface acoustic wave (SAW) transducers being mass sensitive. Mathematical derivations were included and were supported by simulations. In this work, an experimental data set of polymer-coated SAW vapor sensors is investigated. The data set includes 20 diverse polymers tested against 18 diverse organic vapors. It is shown that interfacial adsorption can influence the response behavior of sensors with nonpolar polymers in response to hydrogen-bonding vapors; however, in general, most sensor responses are related to vapor interactions with the polymers. It is also shown that polymer-coated SAW sensor responses can be empirically modeled with LSERs, deriving an LSER for each individual sensor based on its responses to the 18 vapors. Inverse least-squares methods are used to develop models that correlate and predict vapor descriptors from sensor array responses. Successful correlations can be developed by multiple linear regression (MLR), principal components regression (PCR), and partial least-squares (PLS) regression. MLR yields the best fits to the training data, however cross-validation shows that prediction of vapor descriptors for vapors not in the training set is significantly more successful using PCR or PLS. In addition, the optimal dimension of the PCR and PLS models supports the dimensionality of the LSER formulation and SAW response models.

  6. Mechanism of operation and design considerations for surface acoustic wave device vapor sensors

    NASA Astrophysics Data System (ADS)

    Wohltjen, H.

    1984-04-01

    Surface acoustic wave (SAW) devices offer many attractive features for application as vapor phase chemical microsensors. This paper describes the characteristics of SAW devices and techniques by which they can be employed as vapor sensors. The perturbation of SAW amplitude and velocity by polymeric coating films was investigated both theoretically and experimentally. High sensitivity can be achieved when the device is used as the resonating element in a delay line oscillator circuit. A simple equation has been developed from theoretical considerations which offers reasonably accurate quantitative predictions of SAW Device frequency shifts when subjected to a given mass loading. In this mode the SAW device behaves in a fashion very similar to conventional bulk wave quartz crystal microbalance except that the sensitivity can be several orders of magnitude higher and the device size can be several orders of magnitude smaller. Detection of mass changes of less than 1 femtogram by a SAW device having a surface area of 0.0001 square cm. is theoretically possible.

  7. Acoustic Detection Of Loose Particles In Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Kwok, Lloyd C.

    1995-01-01

    Particle-impact-noise-detector (PIND) apparatus used in conjunction with computer program analyzing output of apparatus to detect extraneous particles trapped in pressure sensors. PIND tester essentially shaker equipped with microphone measuring noise in pressure sensor or other object being shaken. Shaker applies controlled vibration. Output of microphone recorded and expressed in terms of voltage, yielding history of noise subsequently processed by computer program. Data taken at sampling rate sufficiently high to enable identification of all impacts of particles on sensor diaphragm and on inner surfaces of sensor cavities.

  8. A surface-acoustic-wave-based cantilever bio-sensor.

    PubMed

    De Simoni, Giorgio; Signore, Giovanni; Agostini, Matteo; Beltram, Fabio; Piazza, Vincenzo

    2015-06-15

    A scalable surface-acoustic-wave- (SAW-) based cantilevered device for portable bio-chemical sensing applications is presented. Even in the current, proof-of-principle implementation this architecture is shown to outperform commercial quartz-crystal microbalances in terms of sensitivity. Adhesion of analytes on a functionalized surface of the cantilever shifts the resonant frequency of a SAW-generating transducer due to the stress-induced variation of the speed of surface acoustic modes. We discuss the relevance of this approach for diagnostics applications based on miniaturized devices.

  9. Surface acoustic wave/silicon monolithic sensor/processor

    NASA Technical Reports Server (NTRS)

    Kowel, S. T.; Kornreich, P. G.; Nouhi, A.; Kilmer, R.; Fathimulla, M. A.; Mehter, E.

    1983-01-01

    A new technique for sputter deposition of piezoelectric zinc oxide (ZnO) is described. An argon-ion milling system was converted to sputter zinc oxide films in an oxygen atmosphere using a pure zinc oxide target. Piezoelectric films were grown on silicon dioxide and silicon dioxide overlayed with gold. The sputtered films were evaluated using surface acoustic wave measurements, X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and resistivity measurements. The effect of the sputtering conditions on the film quality and the result of post-deposition annealing are discussed. The application of these films to the generation of surface acoustic waves is also discussed.

  10. Liquid density analysis of sucrose and alcoholic beverages using polyimide guided Love-mode acoustic wave sensors

    NASA Astrophysics Data System (ADS)

    Turton, Andrew; Bhattacharyya, Debabrata; Wood, David

    2006-02-01

    A liquid density sensor using Love-mode acoustic waves has been developed which is suitable for use in the food and drinks industries. The sensor has an open flat surface allowing immersion into a sample and simple cleaning. A polyimide waveguide layer allows cheap and simple fabrication combined with a robust chemically resistant surface. The low shear modulus of polyimide allows thin guiding layers giving a high sensitivity. A dual structure with a smooth reference device exhibiting viscous coupling with the wave, and a patterned sense area to trap the liquid causing mass loading, allows discrimination of the liquid density from the square root of the density-viscosity product (ρη)0.5. Frequency shift and insertion loss change were proportional to (ρη)0.5 with a non-linear response due to the non-Newtonian nature of viscous liquids at high frequencies. Measurements were made with sucrose solutions up to 50% and different alcoholic drinks. A maximum sensitivity of 0.13 µg cm-3 Hz-1 was achieved, with a linear frequency response to density. This is the highest liquid density sensitivity obtained for acoustic mode sensors to the best of our knowledge.

  11. 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.

  12. Method for Simultaneously Making a Plurality of Acoustic Signal Sensor Elements

    NASA Technical Reports Server (NTRS)

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

    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.

  13. Job-Oriented Basic Skills (JOBS) Program for the Acoustic Sensor Operations Strand.

    ERIC Educational Resources Information Center

    U'Ren, Paula Kabance; Baker, Meryl S.

    An effort was undertaken to develop a job-oriented basic skills curriculum appropriate for the acoustic sensor operations area, which includes members of four ratings: ocean systems technician, aviation antisubmarine warfare operator, sonar technician (surface), and sonar technician (submarine). Analysis of the job duties of the four ratings…

  14. Array gain for a conformal acoustic vector sensor array: An experimental study

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Yang, Yi-Xin; He, Zheng-Yao; Lei, Bo; Sun, Chao; Ma, Yuan-Liang

    2016-12-01

    An acoustic vector sensor can measure the components of particle velocity and the acoustic pressure at the same point simultaneously, which provides a larger array gain against the ambient noise and a higher angular resolution than the omnidirectional pressure sensor. This paper presents an experimental study of array gain for a conformal acoustic vector sensor array in a practical environment. First, the manifold vector is calculated using the real measured data so that the effects of array mismatches can be minimized. Second, an optimal beamformer with a specific spatial response on the basis of the stable directivity of the ambient noise is designed, which can effectively suppress the ambient noise. Experimental results show that this beamformer for the conformal acoustic vector sensor array provides good signal-to-noise ratio enhancement and is more advantageous than the delay-and-sum and minimum variance distortionless response beamformers. Project supported by the China Postdoctoral Science Foundation (Grant No. 2016M592782) and the National Natural Science Foundation of China (Grant Nos. 11274253 and 11604259).

  15. Diaphragm based long cavity Fabry-Perot fiber acoustic sensor using phase generated carrier

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Lin, Jie; Liu, Huan; Ma, Yuan; Yan, Lei; Jin, Peng

    2017-01-01

    A diaphragm based long cavity Fabry-Perot interferometric fiber acoustic sensor is proposed. The Fabry-Perot cavity is formed by a flat fiber facet and an ultra-thin silver diaphragm with a 6-meter long fiber inserted in the cavity. A narrow-linewidth ring-cavity erbium-doped fiber laser is applied to demodulate the sensing signal in the phase generated carrier algorithm. Experimental results have demonstrated that the phase sensitivity is about -140 dB re 1 rad/μPa at 2 kHz. The noise equivalent acoustic signal level is 60.6 μPa/Hz1/2 and the dynamic range is 65.1 dB-SPL at 2 kHz. The sensor is suitable for sensing of weak acoustic signals.

  16. Source localization from an elevated acoustic sensor array in a refractive atmosphere.

    PubMed

    Ostashev, Vladimir E; Scanlon, Michael V; Wilson, D Keith; Vecherin, Sergey N

    2008-12-01

    Localization of sound sources on the ground from an acoustic sensor array elevated on a tethered aerostat is considered. To improve estimation of the source coordinates, one should take into account refraction of sound rays due to atmospheric stratification. Using a geometrical acoustics approximation for a stratified moving medium, formulas for the source coordinates are derived that account for sound refraction. The source coordinates are expressed in terms of the direction of sound propagation as measured by the sensor array, its coordinates, and the vertical profiles of temperature and wind velocity. Employing these formulas and typical temperature and wind velocity profiles in the atmosphere, it is shown numerically that sound refraction is important for accurate predictions of the source coordinates. Furthermore, it is shown that the effective sound speed approximation, which is widely used in atmospheric acoustics, fails to correctly predict the source coordinates if the grazing angle of sound propagation is relatively large.

  17. Bio-Inspired Miniature Direction Finding Acoustic Sensor

    PubMed Central

    Wilmott, Daniel; Alves, Fabio; Karunasiri, Gamani

    2016-01-01

    A narrowband MEMS direction finding sensor has been developed based on the mechanically coupled ears of the Ormia Ochracea fly. The sensor consists of two wings coupled at the middle and attached to a substrate using two legs. The sensor operates at its bending resonance frequency and has cosine directional characteristics similar to that of a pressure gradient microphone. Thus, the directional response of the sensor is symmetric about the normal axis making the determination of the direction ambiguous. To overcome this shortcoming two sensors were assembled with a canted angle similar to that employed in radar bearing locators. The outputs of two sensors were processed together allowing direction finding with no requirement of knowing the incident sound pressure level. At the bending resonant frequency of the sensors (1.69 kHz) an output voltage of about 25 V/Pa was measured. The angle uncertainty of the bearing of sound ranged from less than 0.3° close to the normal axis (0°) to 3.4° at the limits of coverage (±60°) based on the 30° canted angle used. These findings indicate the great potential to use dual MEMS direction finding sensor assemblies to locate sound sources with high accuracy. PMID:27440657

  18. Bio-Inspired Miniature Direction Finding Acoustic Sensor

    NASA Astrophysics Data System (ADS)

    Wilmott, Daniel; Alves, Fabio; Karunasiri, Gamani

    2016-07-01

    A narrowband MEMS direction finding sensor has been developed based on the mechanically coupled ears of the Ormia Ochracea fly. The sensor consists of two wings coupled at the middle and attached to a substrate using two legs. The sensor operates at its bending resonance frequency and has cosine directional characteristics similar to that of a pressure gradient microphone. Thus, the directional response of the sensor is symmetric about the normal axis making the determination of the direction ambiguous. To overcome this shortcoming two sensors were assembled with a canted angle similar to that employed in radar bearing locators. The outputs of two sensors were processed together allowing direction finding with no requirement of knowing the incident sound pressure level. At the bending resonant frequency of the sensors (1.69 kHz) an output voltage of about 25 V/Pa was measured. The angle uncertainty of the bearing of sound ranged from less than 0.3° close to the normal axis (0°) to 3.4° at the limits of coverage (±60°) based on the 30° canted angle used. These findings indicate the great potential to use dual MEMS direction finding sensor assemblies to locate sound sources with high accuracy.

  19. Acoustic Streaming and Heat and Mass Transfer Enhancement

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Gopinath, A.

    1996-01-01

    A second order effect associated with high intensity sound field, acoustic streaming has been historically investigated to gain a fundamental understanding of its controlling mechanisms and to apply it to practical aspects of heat and mass transfer enhancement. The objectives of this new research project are to utilize a unique experimental technique implementing ultrasonic standing waves in closed cavities to study the details of the generation of the steady-state convective streaming flows and of their interaction with the boundary of ultrasonically levitated near-spherical solid objects. The goals are to further extend the existing theoretical studies of streaming flows and sample interactions to higher streaming Reynolds number values, for larger sample size relative to the wavelength, and for a Prandtl and Nusselt numbers parameter range characteristic of both gaseous and liquid host media. Experimental studies will be conducted in support to the theoretical developments, and the crucial impact of microgravity will be to allow the neglect of natural thermal buoyancy. The direct application to heat and mass transfer in the absence of gravity will be emphasized in order to investigate a space-based experiment, but both existing and novel ground-based scientific and technological relevance will also be pursued.

  20. Laboratory comparisons of acoustic and optical sensors for microbubble measurement

    NASA Technical Reports Server (NTRS)

    Su, Ming Yang; Todoroff, Douglas; Cartmill, John

    1994-01-01

    This paper presents the results of a recent comparison between three microbubble size spectrum measurement systems. These systems are the light-scattering bubble counter, the photographic bubble-imaging system, and the acoustic resonator array. Good agreement was formed among these three systems over the bubble size range appropriate for each system.

  1. Properties of high sensitivity ZnO surface acoustic wave sensors on SiO 2/(1 0 0) Si substrates

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, Soumya; Iliadis, Agis A.

    2008-11-01

    The properties of ZnO/SiO2/Si surface acoustic wave (SAW) Love mode sensors were examined and optimized to achieve high mass sensitivity. SAW devices A and B, were designed and fabricated to operate at resonant frequencies around 0.7 and 1.5 GHz. The ZnO films grown by pulsed laser deposition on SiO2/Si demonstrated c-axis growth and the fabricated devices showed guided shear horizontal surface acoustic wave (or Love mode) propagation. Acoustic phase velocity in the ZnO layer was measured in both devices A and B and theoretical and experimental evaluation of the mass sensitivity showed that the maximum sensitivity is obtained for devices with ZnO guiding layer thicknesses of 340 nm and 160 nm for devices A and B, respectively. The performance of the SAW sensors was validated by measuring the mass of a well-characterized polystyrene-polyacrylic acid diblock copolymer film. For the optimized sensors, maximum mass sensitivity values were as high as 4.309 μm2/pg for device A operating at 0.7477 GHz, and 8.643 μm2/pg for device B operating at 1.5860 GHz. The sensors demonstrated large frequency shifts per applied mass (0.1-4 MHz), excellent linearity, and extended range in the femto-gram region. The large frequency shifts indicated that these sensors have the potential to measure mass two to three orders of magnitude lower in the atto-gram range.

  2. Development of a surface acoustic wave sensor for in-situ monitoring of volatile organic compounds.

    SciTech Connect

    McGrath, Lucas K.; Wright, Jerome L.; Ho, Clifford Kuofei; Rawlinson, Kim Scott; Lindgren, Eric Richard

    2003-08-01

    This paper describes the development of a surface-acoustic-wave (SAW) sensor that is designed to be operated continuously and in situ to detect volatile organic compounds. A ruggedized stainless-steel package that encases the SAW device and integrated circuit board allows the sensor to be deployed in a variety of media including air, soil, and even water. Polymers were optimized and chosen based on their response to chlorinated aliphatic hydrocarbons (e.g., trichloroethylene), which are common groundwater contaminants. Initial testing indicates that a running-average data-logging algorithm can reduce the noise and increase the sensitivity of the in-situ sensor.

  3. Implementation of distributed feedback fiber laser sensor for acoustic measurements in hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Chen, Rongzhang; Yan, Aidong; Zaghloul, Mohamed A. S.; Lu, Guanyi; Bunger, Andrew P.; Miller, Gary A.; Cranch, Geoffrey A.; Chen, Kevin P.

    2016-09-01

    A distributed feedback (DFB) fiber laser strain sensor was implemented to measure acoustic emission induced by the hydraulic fracturing process. A study of practical sensor mounting configurations and their characteristics was carried out to find a practical solution. Combining the suitable mounting configuration and ultrahigh strain sensitivity of the DFB fiber laser, the evolution of the hydraulic fracturing process was well monitored. This study shows that fiber lasers can be useful alternatives to piezoelectric sensors in the field of hydraulic fracturing for gas and oil extraction.

  4. The quality of our drinking water: aluminium determination with an acoustic wave sensor.

    PubMed

    Veríssimo, Marta I S; Gomes, M Teresa S R

    2008-06-09

    A new methodology based on an inexpensive aluminium acoustic wave sensor is presented. Although the aluminium sensor has already been reported, and the composition of the selective membrane is known, the low detection limits required for the analysis of drinking water, demanded the inclusion of a preconcentration stage, as well as an optimization of the sensor. The necessary coating amount was established, as well as the best preconcentration protocol, in terms of oxidation of organic matter and aluminium elution from the Chelex-100. The methodology developed with the acoustic wave sensor allowed aluminium quantitation above 0.07 mg L(-1). Several water samples from Portugal were analysed using the acoustic wave sensor, as well as by UV-vis spectrophotometry. Results obtained with both methodologies were not statistically different (alpha=0.05), both in terms of accuracy and precision. This new methodology proved to be adequate for aluminium quantitation in drinking water and showed to be faster and less reagent consuming than the UV spectrophotometric methodology.

  5. New Polymer Coatings for Chemically Selective Mass Sensors

    NASA Technical Reports Server (NTRS)

    Sims, S. C.; Wright, Cassandra; Cobb, J.; McCalla, T.; Revelle, R.; Morris, V. R.; Pollack, S. K.

    1997-01-01

    There is a current need to develop sensitive and chemically specific sensors for the detection of nitric acid for in-situ measurements in the atmosphere. Polymer coatings have been synthesized and tested for their sensitivity and selectivity to nitric acid. A primary requirement for these polymers is detectability down to the parts per trillion range. The results of studies using these polymers as coatings for quartz crystal microbalances (QCM) and surface acoustic wave (SAW) devices will be presented.

  6. MEMS based hair flow-sensors as model systems for acoustic perception studies

    NASA Astrophysics Data System (ADS)

    Krijnen, Gijs J. M.; Dijkstra, Marcel; van Baar, John J.; Shankar, Siripurapu S.; Kuipers, Winfred J.; de Boer, Rik J. H.; Altpeter, Dominique; Lammerink, Theo S. J.; Wiegerink, Remco

    2006-02-01

    Arrays of MEMS fabricated flow sensors inspired by the acoustic flow-sensitive hairs found on the cerci of crickets have been designed, fabricated and characterized. The hairs consist of up to 1 mm long SU-8 structures mounted on suspended membranes with normal translational and rotational degrees of freedom. Electrodes on the membrane and on the substrate form variable capacitors, allowing for capacitive read-out. Capacitance versus voltage, frequency dependence and directional sensitivity measurements have been successfully carried out on fabricated sensor arrays, showing the viability of the concept. The sensors form a model system allowing for investigations on sensory acoustics by their arrayed nature, their adaptivity via electrostatic interaction (frequency tuning and parametric amplification) and their susceptibility to noise (stochastic resonance).

  7. MEMS based hair flow-sensors as model systems for acoustic perception studies.

    PubMed

    Krijnen, Gijs J M; Dijkstra, Marcel; van Baar, John J; Shankar, Siripurapu S; Kuipers, Winfred J; de Boer, Rik J H; Altpeter, Dominique; Lammerink, Theo S J; Wiegerink, Remco

    2006-02-28

    Arrays of MEMS fabricated flow sensors inspired by the acoustic flow-sensitive hairs found on the cerci of crickets have been designed, fabricated and characterized. The hairs consist of up to 1 mm long SU-8 structures mounted on suspended membranes with normal translational and rotational degrees of freedom. Electrodes on the membrane and on the substrate form variable capacitors, allowing for capacitive read-out. Capacitance versus voltage, frequency dependence and directional sensitivity measurements have been successfully carried out on fabricated sensor arrays, showing the viability of the concept. The sensors form a model system allowing for investigations on sensory acoustics by their arrayed nature, their adaptivity via electrostatic interaction (frequency tuning and parametric amplification) and their susceptibility to noise (stochastic resonance).

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  9. Adaptive Noise Reduction Techniques for Airborne Acoustic Sensors

    DTIC Science & Technology

    2012-01-01

    25 4.3 Super Kraft Monocoupe 90A RC airplane. . . . . . . . . . . . . . . . . . . . . . . 27 4.4 Access panel for fuselage of...begin clipping. This is an important consideration for airborne acoustic sensing, as the sound level aboard a UAV must not cause saturation of the...specifications of the Monocoupe used for this experiment are in Table 4.3. 26 Figure 4.3: Super Kraft Monocoupe 90A RC airplane. Figure 4.4: Access panel for

  10. MEMS directional acoustic sensor for locating sound sources

    NASA Astrophysics Data System (ADS)

    Karunasiri, Gamani; Alves, Fabio; Swan, William

    2016-02-01

    The conventional directional sound sensing systems employ an array of spatially separated microphones to achieve directional sensing. However, there are insects such as Ormia ochracea fly that can determine the direction of sound using a miniature hearing organ much smaller than the wavelength of sound it detects. The MEMS based sensors mimicking the fly's hearing system was fabricated using SOI substrate with 25 micrometer device layer. The sensor was designed to operate around 1.7 kHz, consists of two 1.2 mm × 1.2 mm wings connected in the middle by a 3 mm × 30 micrometer bridge. The entire structure is connected to the substrate by two torsional legs at the center. The sensor operates at its bending resonance frequency and has cosine directional characteristics similar to that of a pressure gradient microphone. For unambiguously determining the direction of sound, two sensors were assembled with a canted angle and outputs of the two sensors were processed to uniquely locate the bearing. At the bending resonant frequency (1.7 kHz) an output voltage of about 25 V/Pa was measured. The uncertainty of the bearing of sound ranged from less than 0.3 degrees close to the normal axis (0 degree) to 3 degrees at the limits of coverage (+/- 60 degrees) based on the 30 degree canted angle used. These findings indicate the potential use of a dual MEMS direction finding sensor assembly to locate sound sources with high accuracy.

  11. A methodology for analyzing an acoustic scene in sensor arrays

    NASA Astrophysics Data System (ADS)

    Man, Hong; Hohil, Myron E.; Desai, Sachi

    2007-10-01

    Presented here is a novel clustering method for Hidden Markov Models (HMMs) and its application in acoustic scene analysis. In this method, HMMs are clustered based on a similarity measure for stochastic models defined as the generalized probability product kernel (GPPK), which can be efficiently evaluated according to a fast algorithm introduced by Chen and Man (2005) [1]. Acoustic signals from various sources are partitioned into small frames. Frequency features are extracted from each of the frames to form observation vectors. These frames are further grouped into segments, and an HMM is trained from each of such segments. An unknown segment is categorized with a known event if its HMM has the closest similarity with the HMM from the corresponding labeled segment. Experiments are conducted on an underwater acoustic dataset from Steven Maritime Security Laboratory, Data set contains a swimmer signature, a noise signature from the Hudson River, and a test sequence with a swimmer in the Hudson River. Experimental results show that the proposed method can successfully associate the test sequence with the swimmer signature at very high confidence, despite their different time behaviors.

  12. A micro-Doppler sonar for acoustic surveillance in sensor networks

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaonian

    Wireless sensor networks have been employed in a wide variety of applications, despite the limited energy and communication resources at each sensor node. Low power custom VLSI chips implementing passive acoustic sensing algorithms have been successfully integrated into an acoustic surveillance unit and demonstrated for detection and location of sound sources. In this dissertation, I explore active and passive acoustic sensing techniques, signal processing and classification algorithms for detection and classification in a multinodal sensor network environment. I will present the design and characterization of a continuous-wave micro-Doppler sonar to image objects with articulated moving components. As an example application for this system, we use it to image gaits of humans and four-legged animals. I will present the micro-Doppler gait signatures of a walking person, a dog and a horse. I will discuss the resolution and range of this micro-Doppler sonar and use experimental results to support the theoretical analyses. In order to reduce the data rate and make the system amenable to wireless sensor networks, I will present a second micro-Doppler sonar that uses bandpass sampling for data acquisition. Speech recognition algorithms are explored for biometric identifications from one's gait, and I will present and compare the classification performance of the two systems. The acoustic micro-Doppler sonar design and biometric identification results are the first in the field as the previous work used either video camera or microwave technology. I will also review bearing estimation algorithms and present results of applying these algorithms for bearing estimation and tracking of moving vehicles. Another major source of the power consumption at each sensor node is the wireless interface. To address the need of low power communications in a wireless sensor network, I will also discuss the design and implementation of ultra wideband transmitters in a three dimensional

  13. Integration of acoustical sensors into the KM3NeT optical modules

    SciTech Connect

    Enzenhöfer, A.; Collaboration: KM3NeT Collaboration

    2014-11-18

    The next generation multi-cubic-kilometre water Cherenkov neutrino telescope will be build in the Mediterranean Sea. This telescope, called KM3NeT, is currently entering a first construction phase. The KM3NeT research infrastructure will comprise 690 so-called Detection Units in its final design which will be anchored to the sea bed and held upright by submerged floats. The positions of these Detection Units, several hundred metres in length, and their attached Optical Modules for the detection of Cherenkov light have to be monitored continously to provide the telescope with its desired pointing precision. A standard way to do this is the utilisation of an acoustic positioning system using emitters at fixed positions and receivers distributed along the Detection Units. The KM3NeT neutrino telescope comprises a custom-made acoustic positioning system with newly designed emitters attached to the anchors of the Detection Units and custom-designed receivers attached to the Detection Units. This article describes an approach for a receiver and its performance. The proposed Opto-Acoustical Modules combine the optical sensors for the telescope with the acoustical sensors necessary for the positioning of the module itself. This combination leads to a compact design suited for an easy deployment of the numerous Detection Units. Furthermore, the instrumented volume can be used for scientific analyses such as marine science and acoustic particle detection.

  14. Measurement of cantilever vibration using impedance-loaded surface acoustic wave sensor

    NASA Astrophysics Data System (ADS)

    Oishi, Masaki; Hamashima, Hiromitsu; Kondoh, Jun

    2016-07-01

    In this study, an impedance-loaded surface acoustic wave (SAW) sensor was demonstrated to monitor the vibration frequency. Commercialized pressure sensors and a variable capacitor were chosen as external sensors, which were connected to a reflector on a SAW device. As the reflection coefficient of the reflector depended on the impedance, the echo amplitude was influenced by changes in the impedance of the external sensor. The vibration frequency of the cantilever was determined by monitoring the echo amplitude of the SAW device. Moreover, the attenuation constant of an envelope was estimated. The results of our feasibility study indicate that the impedance-loaded SAW sensor can be applied as a detector for structural health monitoring.

  15. Full bandwidth calibration procedure for acoustic probes containing a pressure and particle velocity sensor.

    PubMed

    Basten, Tom G H; de Bree, Hans-Elias

    2010-01-01

    Calibration of acoustic particle velocity sensors is still difficult due to the lack of standardized sensors to compare with. Recently it is shown by Jacobsen and Jaud [J. Acoust. Soc. Am. 120, 830-837 (2006)] that it is possible to calibrate a sound pressure and particle velocity sensor in free field conditions at higher frequencies. This is done by using the known acoustic impedance at a certain distance of a spherical loudspeaker. When the sound pressure is measured with a calibrated reference microphone, the particle velocity can be calculated from the known impedance and the measured pressure. At lower frequencies, this approach gives unreliable results. The method is now extended to lower frequencies by measuring the acoustic pressure inside the spherical source. At lower frequencies, the sound pressure inside the sphere is proportional to the movement of the loudspeaker membrane. If the movement is known, the particle velocity in front of the loudspeaker can be derived. This low frequency approach is combined with the high frequency approach giving a full bandwidth calibration procedure which can be used in free field conditions using a single calibration setup. The calibration results are compared with results obtained with a standing wave tube.

  16. High Frequency Acoustic Sensor Dedicated to the High Resolution Measurement of Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Meignen, Pierre-Antoine; Le Clézio, Emmanuel; Despaux, Gilles

    Through acoustic signature, scanning acoustic microscopy can be used to quantify local mechanical properties of a medium thanks to the generation of surface waves, mostly Rayleigh waves. Despite being quite effective, this method requires to evaluate the mechanical properties of a single point the acquisition of many ultrasonic signals. This process is then time-consuming and is hardly adaptable to quantitative imaging. The solution considered in this paper to speed-up the method is to design a multi-element sensor allowing the extraction of information on Rayleigh waves with a reduced number of acquisitions. The work is conducted along two axes. As a first step, a model allowing the simulation of the acoustic wave behavior at a fluid/solid interface is developed. This model leads to a better understanding of the characterization of the mechanical properties and to the definition of an adapted sensor's design. As a second step, an experimental method for acoustic field reconstruction is used to characterize the multi-elements sensor and measurements of mechanical properties were done.

  17. Acoustic emission localization in plates with dispersion and reverberations using sparse PZT sensors in passive mode

    NASA Astrophysics Data System (ADS)

    Perelli, Alessandro; De Marchi, Luca; Marzani, Alessandro; Speciale, Nicolò

    2012-02-01

    A strategy for the localization of acoustic emissions (AE) in plates with dispersion and reverberation is proposed. The procedure exploits signals received in passive mode by sparse conventional piezoelectric transducers and a three-step processing framework. The first step consists in a signal dispersion compensation procedure, which is achieved by means of the warped frequency transform. The second step concerns the estimation of the differences in arrival time (TDOA) of the acoustic emission at the sensors. Complexities related to reflections and plate resonances are overcome via a wavelet decomposition of cross-correlating signals where the mother function is designed by a synthetic warped cross-signal. The magnitude of the wavelet coefficients in the warped distance-frequency domain, in fact, precisely reveals the TDOA of an acoustic emission at two sensors. Finally, in the last step the TDOA data are exploited to locate the acoustic emission source through hyperbolic positioning. The proposed procedure is tested with a passive network of three/four piezo-sensors located symmetrically and asymmetrically with respect to the plate edges. The experimentally estimated AE locations are close to those theoretically predicted by the Cramèr-Rao lower bound.

  18. A self-mixing based ring-type fiber-optic acoustic sensor

    NASA Astrophysics Data System (ADS)

    Wang, Lutang; Wu, Chunxu; Fang, Nian

    2014-07-01

    A novel, simple fiber-optic acoustic sensor consisting of a self-mixing effect based laser source and a ring-type interferometer is presented. With weak external optical feedbacks, the acoustic wave signals can be detected by measuring the changes of oscillating frequency of the laser diode, induced by the disturbances of sensing fiber, with the ring-type interferometer. The operation principles of the sensor system are explored in-depth and the experimental researches are carried out. The acoustic wave signals produced by various actions, such as by pencil broken, mental pin free falling and PZT are detected for evaluating the sensing performances of the experimental system. The investigation items include the sensitivity as well as frequency responses of the sensor system. An experiment for the detection of corona discharges is carried out, which occur in a high-voltage environment between two parallel copper electrodes, under different humidity levels. The satisfied experimental results are obtained. These experimental results well prove that our proposed sensing system has very high sensitivity and excellent high frequency responses characteristics in the detections of weak, high-frequency acoustic wave signals.

  19. Acoustic localization of antbirds in a Mexican rainforest using a wireless sensor network.

    PubMed

    Collier, Travis C; Kirschel, Alexander N G; Taylor, Charles E

    2010-07-01

    Acoustic localization is a promising method to passively observe vocal animal species, but remains difficult and time consuming to employ. To reduce the labor intensity and impact of deployment, an acoustic localization system has been developed consisting of battery powered wireless sensor nodes. The system also has the ability to perform an acoustic self-survey, which compares favorably in accuracy to global positioning system survey methods, especially in environments such as forest. The self-survey and localization accuracy of the system was tested in the neotropical rainforest of Chiapas, Mexico. A straight-forward and robust correlation sum localization computation method was utilized and is described in detail. Both free-ranging wild antbird songs and songs played from a speaker were localized with mean errors of 0.199 m and 0.445 m, respectively. Finally, additional tests utilizing only a short segment of each song or a subset of sensor nodes were performed and found to minimally affect localization accuracy. The use of a wireless sensor network for acoustic localization of animal vocalizations offers greater ease and flexibility of deployment than wired microphone arrays without sacrificing accuracy.

  20. The application of accelerometers to the measurement of compliant baffle characteristics: Effects of sensor size and mass

    SciTech Connect

    Martin, N.C.; Dees, R.N.; Sachs, D.A.

    1996-04-01

    Compliant layers find use in sonar applications for the purpose of reducing either the surface motion or fluid pressure transmitted to sonar elements due to structural vibration of the underlying ship structure. Although the characterization of candidate compliant materials has traditionally been accomplished using hydrophones, recent test capabilities have employed accelerometers at the compliant surface. For excitation of the compliant layer at acoustic wavenumbers the interaction of the mass of the sensor with the surface compliance leads to a resonant response which reduces the accuracy of the measurement. This effect is mitigated by adding syntactic foam to produce a composite sensor which is neutrally buoyant. For excitations at wavenumbers greater than the acoustic wavenumber (e.g.: plate flexural wavenumbers) neutrally buoyant sensors continue to interact with the compliant surface to reduce the sensor response. Increases in sensor height lead to reductions in sensor response. Finite element calculations combined with simple analytic models have been used to evaluate the requirements on sensor mass and size in order to make accurate measurements of compliant layer characteristics. {copyright} {ital 1996 American Institute of Physics.}

  1. Pressure transducer for measuring acoustic radiation force based on a magnetic sensor

    NASA Astrophysics Data System (ADS)

    Kamimura, H. A. S.; Pavan, T. Z.; Almeida, T. W. J.; Pádua, M. L. A.; Baggio, A. L.; Fatemi, M.; Carneiro, A. A. O.

    2011-01-01

    This work presents a pressure transducer based on a magnetic sensor to measure acoustic radiation force (ARF) and small displacements. The methodology presented in this paper allowed this transducer to be calibrated for use as an acoustic pressure and intensity meter. It can control the acoustic intensity emitted by ultrasound used, for example, in ARF impulse imaging, vibro-acoustography and high-intensity focused ultrasound techniques. The device comprises a magnet, a membrane, a magnetoresistive sensor and a coil to cancel the external magnetic field. When ARF is applied to the membrane, the magnetic field on the sensor changes due to the magnetic target displacement. The variation of the output signal from the magnetic transducer is proportional to the acoustic pressure applied to the membrane. A focused ultrasound transducer with a central frequency of 3 MHz was used to apply a continuous ARF. The sensitivities of the magnetic transducer as an acoustic pressure and intensity meter, evaluated in water, were respectively 0.597 µV MPa-1 and 0.073 µV (W cm-2)-1/2, while those of the needle hydrophone (Onda model HNP-0400) used in the magnetic transducer calibration were respectively, 0.5024 mV MPa-1 and 6.153 mV (W cm-2)-1/2. The transducer resolution to displacement is 5 nm and 6 dB of signal attenuation occurs for 7° of misalignment. The transducer responded well to acoustic pressure in water above 200 kPa.

  2. A Fiber-Optic Sensor for Acoustic Emission Detection in a High Voltage Cable System.

    PubMed

    Zhang, Tongzhi; Pang, Fufei; Liu, Huanhuan; Cheng, Jiajing; Lv, Longbao; Zhang, Xiaobei; Chen, Na; Wang, Tingyun

    2016-11-30

    We have proposed and demonstrated a Michelson interferometer-based fiber sensor for detecting acoustic emission generated from the partial discharge (PD) of the accessories of a high-voltage cable system. The developed sensor head is integrated with a compact and relatively high sensitivity cylindrical elastomer. Such a sensor has a broadband frequency response and a relatively high sensitivity in a harsh environment under a high-voltage electric field. The design and fabrication of the sensor head integrated with the cylindrical elastomer is described, and a series of experiments was conducted to evaluate the sensing performance. The experimental results demonstrate that the sensitivity of our developed sensor for acoustic detection of partial discharges is 1.7 rad / ( m ⋅ Pa ) . A high frequency response up to 150 kHz is achieved. Moreover, the relatively high sensitivity for the detection of PD is verified in both the laboratory environment and gas insulated switchgear. The obtained results show the great potential application of a Michelson interferometer-based fiber sensor integrated with a cylindrical elastomer for in-situ monitoring high-voltage cable accessories for safety work.

  3. A Fiber-Optic Sensor for Acoustic Emission Detection in a High Voltage Cable System

    PubMed Central

    Zhang, Tongzhi; Pang, Fufei; Liu, Huanhuan; Cheng, Jiajing; Lv, Longbao; Zhang, Xiaobei; Chen, Na; Wang, Tingyun

    2016-01-01

    We have proposed and demonstrated a Michelson interferometer-based fiber sensor for detecting acoustic emission generated from the partial discharge (PD) of the accessories of a high-voltage cable system. The developed sensor head is integrated with a compact and relatively high sensitivity cylindrical elastomer. Such a sensor has a broadband frequency response and a relatively high sensitivity in a harsh environment under a high-voltage electric field. The design and fabrication of the sensor head integrated with the cylindrical elastomer is described, and a series of experiments was conducted to evaluate the sensing performance. The experimental results demonstrate that the sensitivity of our developed sensor for acoustic detection of partial discharges is 1.7 rad/(m⋅Pa). A high frequency response up to 150 kHz is achieved. Moreover, the relatively high sensitivity for the detection of PD is verified in both the laboratory environment and gas insulated switchgear. The obtained results show the great potential application of a Michelson interferometer-based fiber sensor integrated with a cylindrical elastomer for in-situ monitoring high-voltage cable accessories for safety work. PMID:27916900

  4. Experimental Results of Underwater Cooperative Source Localization Using a Single Acoustic Vector Sensor

    PubMed Central

    Felisberto, Paulo; Rodriguez, Orlando; Santos, Paulo; Ey, Emanuel; Jesus, Sérgio M.

    2013-01-01

    This paper aims at estimating the azimuth, range and depth of a cooperative broadband acoustic source with a single vector sensor in a multipath underwater environment, where the received signal is assumed to be a linear combination of echoes of the source emitted waveform. A vector sensor is a device that measures the scalar acoustic pressure field and the vectorial acoustic particle velocity field at a single location in space. The amplitudes of the echoes in the vector sensor components allow one to determine their azimuth and elevation. Assuming that the environmental conditions of the channel are known, source range and depth are obtained from the estimates of elevation and relative time delays of the different echoes using a ray-based backpropagation algorithm. The proposed method is tested using simulated data and is further applied to experimental data from the Makai'05 experiment, where 8–14 kHz chirp signals were acquired by a vector sensor array. It is shown that for short ranges, the position of the source is estimated in agreement with the geometry of the experiment. The method is low computational demanding, thus well-suited to be used in mobile and light platforms, where space and power requirements are limited. PMID:23857257

  5. Experimental results of underwater cooperative source localization using a single acoustic vector sensor.

    PubMed

    Felisberto, Paulo; Rodriguez, Orlando; Santos, Paulo; Ey, Emanuel; Jesus, Sérgio M

    2013-07-12

    This paper aims at estimating the azimuth, range and depth of a cooperative broadband acoustic source with a single vector sensor in a multipath underwater environment, where the received signal is assumed to be a linear combination of echoes of the source emitted waveform. A vector sensor is a device that measures the scalar acoustic pressure field and the vectorial acoustic particle velocity field at a single location in space. The amplitudes of the echoes in the vector sensor components allow one to determine their azimuth and elevation. Assuming that the environmental conditions of the channel are known, source range and depth are obtained from the estimates of elevation and relative time delays of the different echoes using a ray-based backpropagation algorithm. The proposed method is tested using simulated data and is further applied to experimental data from the Makai'05 experiment, where 8-14 kHz chirp signals were acquired by a vector sensor array. It is shown that for short ranges, the position of the source is estimated in agreement with the geometry of the experiment. The method is low computational demanding, thus well-suited to be used in mobile and light platforms, where space and power requirements are limited.

  6. A smart sensor system for trace organic vapor detection using a temperature-controlled array of surface acoustic wave vapor sensors, automated preconcentrator tubes, and pattern recognition

    SciTech Connect

    Grate, J.W.; Rose-Pehrsson, S.L.; Klusty, M.; Wohltjen, H.

    1993-05-01

    A smart sensor system for the detection, of toxic organophosphorus and toxic organosulfur vapors at trace concentrations has been designed, fabricated, and tested against a wide variety of vapor challenges. The key features of the system are: An array of four surface acoustic wave (SAW) vapor sensors, temperature control of the vapor sensors, the use of pattern recognition to analyze the sensor data, and an automated sampling system including thermally-desorbed preconcentrator tubes (PCTs).

  7. Multipoint dynamically reconfigure adaptive distributed fiber optic acoustic emission sensor (FAESense) system for condition based maintenance

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar; Prohaska, John; Kempen, Connie; Esterkin, Yan; Sun, Sunjian; Krishnaswamy, Sridhar

    2010-09-01

    This paper describes preliminary results obtained under a Navy SBIR contract by Redondo Optics Inc. (ROI), in collaboration with Northwestern University towards the development and demonstration of a next generation, stand-alone and fully integrated, dynamically reconfigurable, adaptive fiber optic acoustic emission sensor (FAESense™) system for the in-situ unattended detection and localization of shock events, impact damage, cracks, voids, and delaminations in new and aging critical infrastructures found in ships, submarines, aircraft, and in next generation weapon systems. ROI's FAESense™ system is based on the integration of proven state-of-the-art technologies: 1) distributed array of in-line fiber Bragg gratings (FBGs) sensors sensitive to strain, vibration, and acoustic emissions, 2) adaptive spectral demodulation of FBG sensor dynamic signals using two-wave mixing interferometry on photorefractive semiconductors, and 3) integration of all the sensor system passive and active optoelectronic components within a 0.5-cm x 1-cm photonic integrated circuit microchip. The adaptive TWM demodulation methodology allows the measurement of dynamic high frequnency acoustic emission events, while compensating for passive quasi-static strain and temperature drifts. It features a compact, low power, environmentally robust 1-inch x 1-inch x 4-inch small form factor (SFF) package with no moving parts. The FAESense™ interrogation system is microprocessor-controlled using high data rate signal processing electronics for the FBG sensors calibration, temperature compensation and the detection and analysis of acoustic emission signals. Its miniaturized package, low power operation, state-of-the-art data communications, and low cost makes it a very attractive solution for a large number of applications in naval and maritime industries, aerospace, civil structures, the oil and chemical industry, and for homeland security applications.

  8. Acoustic power delivery to pipeline monitoring wireless sensors.

    PubMed

    Kiziroglou, M E; Boyle, D E; Wright, S W; Yeatman, E M

    2017-01-23

    The use of energy harvesting for powering wireless sensors is made more challenging in most applications by the requirement for customization to each specific application environment because of specificities of the available energy form, such as precise location, direction and motion frequency, as well as the temporal variation and unpredictability of the energy source. Wireless power transfer from dedicated sources can overcome these difficulties, and in this work, the use of targeted ultrasonic power transfer as a possible method for remote powering of sensor nodes is investigated. A powering system for pipeline monitoring sensors is described and studied experimentally, with a pair of identical, non-inertial piezoelectric transducers used at the transmitter and receiver. Power transmission of 18mW (Root-Mean-Square) through 1m of a118mm diameter cast iron pipe, with 8mm wall thickness is demonstrated. By analysis of the delay between transmission and reception, including reflections from the pipeline edges, a transmission speed of 1000m/s is observed, corresponding to the phase velocity of the L(0,1) axial and F(1,1) radial modes of the pipe structure. A reduction of power delivery with water-filling is observed, yet over 4mW of delivered power through a fully-filled pipe is demonstrated. The transmitted power and voltage levels exceed the requirements for efficient power management, including rectification at cold-starting conditions, and for the operation of low-power sensor nodes. The proposed powering technique may allow the implementation of energy autonomous wireless sensor systems for monitoring industrial and network pipeline infrastructure.

  9. Source localization with acoustic sensor arrays using generative model based fitting with sparse constraints.

    PubMed

    Velasco, Jose; Pizarro, Daniel; Macias-Guarasa, Javier

    2012-10-15

    This paper presents a novel approach for indoor acoustic source localization using sensor arrays. The proposed solution starts by defining a generative model, designed to explain the acoustic power maps obtained by Steered Response Power (SRP) strategies. An optimization approach is then proposed to fit the model to real input SRP data and estimate the position of the acoustic source. Adequately fitting the model to real SRP data, where noise and other unmodelled effects distort the ideal signal, is the core contribution of the paper. Two basic strategies in the optimization are proposed. First, sparse constraints in the parameters of the model are included, enforcing the number of simultaneous active sources to be limited. Second, subspace analysis is used to filter out portions of the input signal that cannot be explained by the model. Experimental results on a realistic speech database show statistically significant localization error reductions of up to 30% when compared with the SRP-PHAT strategies.

  10. A cantilever based optical fiber acoustic sensor fabricated by femtosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Yuan, Lei; Huang, Jie; Xiao, Hai

    2016-04-01

    In this paper, we present a pure silica micro-cantilever based optical fiber sensor for acoustic wave detection. The cantilever is directly fabricated by fs laser micromachining on an optical fiber tip functioning as an inline Fabry-Perot interferometer (FPI). The applied acoustic wave pressurizes the micro-cantilever beam and the corresponding dynamic signals can be probed by the FPI. The thickness, length, and width of the micro-cantilever beam can be flexibly designed and fabricated so that the sensitivity, frequency response, and the total measurement range can be varied to fit many practical applications. Experimental results will be presented and analyzed. Due to the assembly free fabrication of the fs-laser, multiple micro-cantilever beams could be potentially fabricated in/on a single optical fiber for quasi-distributed acoustic mapping with high spatial resolution.

  11. Source Localization with Acoustic Sensor Arrays Using Generative Model Based Fitting with Sparse Constraints

    PubMed Central

    Velasco, Jose; Pizarro, Daniel; Macias-Guarasa, Javier

    2012-01-01

    This paper presents a novel approach for indoor acoustic source localization using sensor arrays. The proposed solution starts by defining a generative model, designed to explain the acoustic power maps obtained by Steered Response Power (SRP) strategies. An optimization approach is then proposed to fit the model to real input SRP data and estimate the position of the acoustic source. Adequately fitting the model to real SRP data, where noise and other unmodelled effects distort the ideal signal, is the core contribution of the paper. Two basic strategies in the optimization are proposed. First, sparse constraints in the parameters of the model are included, enforcing the number of simultaneous active sources to be limited. Second, subspace analysis is used to filter out portions of the input signal that cannot be explained by the model. Experimental results on a realistic speech database show statistically significant localization error reductions of up to 30% when compared with the SRP-PHAT strategies. PMID:23202021

  12. Acoustic Seaglider

    DTIC Science & Technology

    2008-03-07

    a national naval responsibility. Acoustic sensors on mobile, autonomous platforms will enable basic research topics on temporal and spatial...problem and acoustic navigation and communications within the context of distributed autonomous persistent undersea surveillance sensor networks...Acoustic sensors on mobile, autonomous platforms will enable basic research topics on temporal and spatial coherence and the description of ambient

  13. A new capnograph based on an electro acoustic sensor.

    PubMed

    Folke, M; Hök, B

    2008-01-01

    End tidal carbon dioxide measurements with an electro acoustic capnograph prototype have been demonstrated. The aim of this study was to verify that it is possible to obtain an adequate capnogram using the prototype and to investigate the influence of ambient temperature and humidity variations. By simultaneous measurements with a reference capnograph, on subjects performing exercise, hypo- and hyperventilation, P(ET)CO(2) readings from the reference were compared with the output signal from the prototype. The capnogram from the prototype correlated well with the reference in terms of breath time. The first parts of the expiration and inspiration phases were steeper for the reference than the prototype. The output signal from the prototype correlated well with the reference P(ET)CO(2) readings with a correlation coefficient of 0.93 at varied temperature and relative humidity.

  14. DECAF - Density Estimation for Cetaceans from Passive Acoustic Fixed Sensors

    DTIC Science & Technology

    2008-01-01

    whale density at AUTEC using single hydrophone data; • if time allows, estimation of humpback whale density at PMRF. Project investigators and...classifier for minke and humpback whales; he is also taking the lead on developing methods for estimating density from single fixed sensors, together...this was presented as a poster paper (Marques and Thomas 2008) at the International Statistical Ecology Conference in July 2008. The humpback whale

  15. Acoustic Nondestructive Evaluation of Aircraft Paneling Using Piezoelectric Sensors

    DTIC Science & Technology

    2012-12-01

    year (1, 2). Historically, methods for detecting defects in structures have included visual inspection, x-ray analysis, and ultrasonic ...equations, the final information of interest can be calculated. 9 After squaring all three main equations, we use the elimination method for ...miniaturized antennas may also be implemented to eliminate the need for wires in our system. Such an advancement will make placement of the sensor

  16. A distributed acoustic and temperature sensor using a commercial off-the-shelf DFB laser

    NASA Astrophysics Data System (ADS)

    Muanenda, Y.; Oton, C. J.; Faralli, S.; Nannipieri, T.; Signorini, A.; Di Pasquale, F.

    2015-09-01

    In this paper, we experimentally demonstrate a hybrid distributed acoustic and temperature sensor (DATS) based on Raman and coherent Rayleigh scattering processes in a standard singlemode fiber. A single commercial off-the-shelf DFB laser and a common receiver block are used to implement a highly integrated hybrid sensor system with key industrial applications. Distributed acoustic sensing and Raman temperature measurement are simultaneously performed by exploiting cyclic Simplex pulse coding in a phase-sensitive OTDR and in Raman DTS using direct detection. Suitable control and modulation of the DFB laser ensures inter-pulse incoherence and intra-pulse coherence, enabling accurate long-distance measurement of vibrations and temperature with minimal post-processing.

  17. Acoustic emission source location on large plate-like structures using a local triangular sensor array

    NASA Astrophysics Data System (ADS)

    Aljets, Dirk; Chong, Alex; Wilcox, Steve; Holford, Karen

    2012-07-01

    A new acoustic emission (AE) source location method was developed for large plate-like structures, which evaluates the location of the source using a combined time of flight and modal source location algorithm. Three sensors are installed in a triangular array with a sensor to sensor distance of just a few centimeters. The direction from the sensor array to the AE source can be established by analysing the arrival times of the A0 component of the signal to the three sensors whilst the distance can be evaluated using the separation of S0 and A0 mode at each sensor respectively. The close positioning of the sensors allows the array to be installed in a single housing. This simplifies mounting, wiring and calibration procedures for non-destructive testing (NDT) and structural health monitoring (SHM) applications. Furthermore, this array could reduce the number of sensors needed to monitor large structures compared to other methods. An automatic wave mode identification method is also presented.

  18. Surface Acoustic Wave Ammonia Sensors Based on ST-cut Quartz under Periodic Al Structure.

    PubMed

    Hsu, Cheng-Liang; Shen, Chi-Yen; Tsai, Rume-Tze; Su, Ming-Yau

    2009-01-01

    Surface acoustic wave (SAW) devices are key components for sensing applications. SAW propagation under a periodic grating was investigated in this work. The theoretical method used here is the space harmonic method. We also applied the results of SAW propagation studied in this work to design a two-port resonator with an Al grating on ST-cut quartz. The measured frequency responses of the resonator were similar to the simulation ones. Then, the chemical interface of polyaniline/WO(3) composites was coated on the SAW sensor for ammonia detection. The SAW sensor responded to ammonia gas and could be regenerated using dry nitrogen.

  19. Detection of Adult Beetles Inside the Stored Wheat Mass Based on Their Acoustic Emissions.

    PubMed

    Eliopoulos, P A; Potamitis, I; Kontodimas, D Ch; Givropoulou, E G

    2015-12-01

    The efficacy of bioacoustics in detecting the presence of adult beetles inside the grain mass was evaluated in the laboratory. A piezoelectric sensor and a portable acoustic emission amplifier connected with a computer were used. Adults of the most common beetle pests of stored wheat have been detected in varying population densities (0.1, 0.5, 1, and 2 adults per kilogram of wheat). The verification of the presence of the insect individuals was achieved through automated signal parameterization and classification. We tried out two different ways to detect impulses: 1) by applying a Hilbert transform on the audio recording and 2) by subtracting a noise estimation of the recording from the spectral content of the recording, thus allowing the frequency content of possible impulses to emerge. Prediction for infestation was rated falsely negative in 60-74%, 48-60%, 0-28%, and 0-4% of the cases when actual population density was 0.1, 0.5, 1, and 2 adults per kilogram, respectively, irrespective of pest species. No significant differences were recorded in positive predictions among different species in almost all cases. The system was very accurate (72-100%) in detecting 1 or 2 insects per kilogram of hard wheat grain, which is the standard threshold for classifying a grain mass "clean" or "infested." Our findings are discussed on the basis of enhancing the use of bioacoustics in stored-product IPM framework.

  20. Particle velocity gradient based acoustic mode beamforming for short linear vector sensor arrays.

    PubMed

    Gur, Berke

    2014-06-01

    In this paper, a subtractive beamforming algorithm for short linear arrays of two-dimensional particle velocity sensors is described. The proposed method extracts the highly directional acoustic modes from the spatial gradients of the particle velocity field measured at closely spaced sensors along the array. The number of sensors in the array limits the highest order of modes that can be extracted. Theoretical analysis and numerical simulations indicate that the acoustic mode beamformer achieves directivity comparable to the maximum directivity that can be obtained with differential microphone arrays of equivalent aperture. When compared to conventional delay-and-sum beamformers for pressure sensor arrays, the proposed method achieves comparable directivity with 70%-85% shorter apertures. Moreover, the proposed method has additional capabilities such as high front-back (port-starboard) discrimination, frequency and steer direction independent response, and robustness to correlated ambient noise. Small inter-sensor spacing that results in very compact apertures makes the proposed beamformer suitable for space constrained applications such as hearing aids and short towed arrays for autonomous underwater platforms.

  1. Contributed Review: Recent developments in acoustic energy harvesting for autonomous wireless sensor nodes applications.

    PubMed

    Khan, Farid Ullah; Khattak, Muhammad Umair

    2016-02-01

    Rapid developments in micro electronics, micro fabrication, ultra-large scale of integration, ultra-low power sensors, and wireless technology have greatly reduced the power consumption requirements of wireless sensor nodes (WSNs) and make it possible to operate these devices with energy harvesters. Likewise, other energy harvesters, acoustic energy harvesters (AEHs), have been developed and are gaining swift interest in last few years. This paper presents a review of AEHs reported in the literature for the applications of WSNs. Based on transduction mechanism, there are two types of AEHs: piezoelectric acoustic energy harvesters (PEAEHs) and electromagnetic acoustic energy harvesters (EMAEHs). The reported AEHs are mostly characterized under the sound pressure level (SPL) that ranges from 45 to 161 dB. The range for resonant frequency of the produced AEHs is from 146 Hz to 24 kHz and these produced 0.68 × 10(-6) μW to 30 mW power. The maximum power (30 mW) is produced by a PEAEH, when the harvester is subjected to a SPL of 161 dB and 2.64 kHz frequency. However, for EMAEHs, the maximum power reported is about 1.96 mW (at 125 dB and 143 Hz). Under the comparable SPLs, the power production by the reported EMAEHs is relatively better than that of PEAEHs, moreover, due to lower resonant frequency, the EMAEHs are more feasible for the low frequency band acoustical environment.

  2. An Adaptive OFDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks

    PubMed Central

    Khalil, Issa M.; Gadallah, Yasser; Hayajneh, Mohammad; Khreishah, Abdallah

    2012-01-01

    Underwater acoustic wireless sensor networks (UAWSNs) have many applications across various civilian and military domains. However, they suffer from the limited available bandwidth of acoustic signals and harsh underwater conditions. In this work, we present an Orthogonal Frequency Division Multiple Access (OFDMA)-based Media Access Control (MAC) protocol that is configurable to suit the operating requirements of the underwater sensor network. The protocol has three modes of operation, namely random, equal opportunity and energy-conscious modes of operation. Our MAC design approach exploits the multi-path characteristics of a fading acoustic channel to convert it into parallel independent acoustic sub-channels that undergo flat fading. Communication between node pairs within the network is done using subsets of these sub-channels, depending on the configurations of the active mode of operation. Thus, the available limited bandwidth gets fully utilized while completely avoiding interference. We derive the mathematical model for optimal power loading and subcarrier selection, which is used as basis for all modes of operation of the protocol. We also conduct many simulation experiments to evaluate and compare our protocol with other Code Division Multiple Access (CDMA)-based MAC protocols. PMID:23012517

  3. Effect of acoustic streaming on the mass transfer from a sublimating sphere

    NASA Astrophysics Data System (ADS)

    Kawahara, N.; Yarin, A. L.; Brenn, G.; Kastner, O.; Durst, F.

    2000-04-01

    The effect of the acoustic streaming on the mass transfer from the surface of a sphere positioned in an ultrasonic acoustic levitator is studied both experimentally and theoretically. Acoustic levitation using standing ultrasonic waves is an experimental tool for studying the heat and mass transfer from small solid or liquid samples, because it allows an almost steady positioning of a sample at a fixed location in space. However, the levitator introduces some difficulties. One of the main problems with acoustic levitation is that an acoustic streaming is induced near the sample surface, which affects the heat and mass transfer rates, as characterized by increased Nusselt and Sherwood numbers. The transfer rates are not uniform along the sample surface, and the aim of the present study is to quantify the spatial Sherwood number distribution over the surface of a sphere. The experiments are based on the measurement of the surface shape of a sphere layered with a solid substance as a function of time using a charge-coupled device (CCD) camera with backlighting. The sphere used in this research is a glass sphere layered with a volatile solid substance (naphthalene or camphor). The local mass transfer from the surface both with and without an ultrasonic acoustic field is investigated in order to evaluate the effect of the acoustic streaming. The experimental results are compared with predictions following from the theory outlined [A. L. Yarin, M. Pfaffenlehner, and C. Tropea, J. Fluid Mech. 356, 65 (1998); A. L. Yarin, G. Brenn, O. Kastner, D. Rensink, and C. Tropea, ibid. 399, 151 (1999)] which describes the acoustic field and the resulting acoustic streaming, and the mass transfer at the surface of particles and droplets located in an acoustic levitator. The results are also compared with the experimental data and with the theoretical predictions of Burdukov and Nakoryakov [J. Appl. Mech. Tech. Phys. 6, 51 (1965)], which are valid only in the case of spherical

  4. AURP: An AUV-Aided Underwater Routing Protocol for Underwater Acoustic Sensor Networks

    PubMed Central

    Yoon, Seokhoon; Azad, Abul K.; Oh, Hoon; Kim, Sunghwan

    2012-01-01

    Deploying a multi-hop underwater acoustic sensor network (UASN) in a large area brings about new challenges in reliable data transmissions and survivability of network due to the limited underwater communication range/bandwidth and the limited energy of underwater sensor nodes. In order to address those challenges and achieve the objectives of maximization of data delivery ratio and minimization of energy consumption of underwater sensor nodes, this paper proposes a new underwater routing scheme, namely AURP (AUV-aided underwater routing protocol), which uses not only heterogeneous acoustic communication channels but also controlled mobility of multiple autonomous underwater vehicles (AUVs). In AURP, the total data transmissions are minimized by using AUVs as relay nodes, which collect sensed data from gateway nodes and then forward to the sink. Moreover, controlled mobility of AUVs makes it possible to apply a short-range high data rate underwater channel for transmissions of a large amount of data. To the best to our knowledge, this work is the first attempt to employ multiple AUVs as relay nodes in a multi-hop UASN to improve the network performance in terms of data delivery ratio and energy consumption. Simulations, which are incorporated with a realistic underwater acoustic communication channel model, are carried out to evaluate the performance of the proposed scheme, and the results indicate that a high delivery ratio and low energy consumption can be achieved. PMID:22438740

  5. Acoustic power measurement of high-intensity focused ultrasound transducer using a pressure sensor.

    PubMed

    Zhou, Yufeng

    2015-03-01

    The acoustic power of high-intensity focused ultrasound (HIFU) is an important parameter that should be measured prior to each treatment to guarantee effective and safe outcomes. A new calibration technique was developed that involves estimating the pressure distribution, calculating the acoustic power using an underwater pressure blast sensor, and compensating the contribution of harmonics to the acoustic power. The output of a clinical extracorporeal HIFU system (center frequency of ~1 MHz, p+ = 2.5-57.2 MPa, p(-) = -1.8 to -13.9 MPa, I(SPPA) = 513-22,940 W/cm(2), -6 dB size of 1.6 × 10 mm: lateral × axial) was measured using this approach and then compared with that obtained using a radiation force balance. Similarities were found between each method at acoustic power ranging from 18.2 W to 912 W with an electrical-to-acoustic conversion efficiency of ~42%. The proposed method has advantages of low weight, smaller size, high sensitivity, quick response, high signal-to-noise ratio (especially at low power output), robust performance, and easy operation of HIFU exposimetry measurement.

  6. Parametric excitation of a micro Coriolis mass flow sensor

    NASA Astrophysics Data System (ADS)

    Droogendijk, H.; Groenesteijn, J.; Haneveld, J.; Sanders, R. G. P.; Wiegerink, R. J.; Lammerink, T. S. J.; Lötters, J. C.; Krijnen, G. J. M.

    2012-11-01

    We demonstrate that a micro Coriolis mass flow sensor can be excited in its torsional movement by applying parametric excitation. Using AC-bias voltages for periodic electrostatic spring softening, the flow-filled tube exhibits a steady vibration at suitable voltage settings. Measurements show that the sensor for this type of excitation can be used to measure water flow rates within a range of 0 ± 500 μl/h with an accuracy of 1% full scale error.

  7. Fly Ear Inspired Miniature Acoustic Sensors for Detection and Localization

    DTIC Science & Technology

    2011-07-31

    Journal of Biological Physics Research) 2) A. Lisiewshi, H. Liu , M. Yu, L. Currano, and D . Gee, “Fly-ear inspired micro-sensor for sound source...m Torsional spring k3 5.18 N/m Torsional dashpot c3 2.88×10-5 N s/m Separation of force locations d 1.2×10-3 m Tympanum area s 0.288×10-6 m2...Γ−−Ω + Ω ⎪ ⎪⎩ ⎭ ⎩ ⎭ ⎩ ⎭ , (5) where 2 1 2 2 2 1 2 , 2 sin , 2 j d j ξ φ πχ θ χ η ηξ λ −Ω + Ω Γ = = = −Ω + Ω

  8. Micromechanical Sensor for the Spectral Decomposition of Acoustic Signals

    DTIC Science & Technology

    2012-02-01

    272 APPENDIX A. COUPLED RESONANCE TESTS...transduction. In general, a vibration scavenger consists of a large proof mass suspended through some means and allowed to couple with the external...electret is coupled with vibrational motion to achieve power production. The device uses a Teflon-like polymer film, with the brand name of CYTOP, for the

  9. Acoustic detection and localization of weapons fire by unattended ground sensors and aerostat-borne sensors

    NASA Astrophysics Data System (ADS)

    Naz, P.; Marty, Ch.; Hengy, S.; Miller, L. S.

    2009-05-01

    The detection and localization of artillery guns on the battlefield is envisaged by means of acoustic and seismic waves. The main objective of this work is to examine the different frequency ranges usable for the detection of small arms, mortars, and artillery guns on the same hardware platform. The main stages of this study have consisted of: data acquisition of the acoustic signals of the different weapons used, signal processing and evaluation of the localization performance for various types of individual arrays, and modeling of the wave propagation in the atmosphere. The study of the propagation effects on the signatures of these weapons is done by comparing the acoustic signals measured during various days, at ground level and at the altitude of our aerostat (typically 200 m). Numerical modeling has also been performed to reinforce the interpretation of the experimental results.

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

    SciTech Connect

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

    2013-02-14

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

  11. Advanced vapor recognition materials for selective and fast responsive surface acoustic wave sensors: a review.

    PubMed

    Afzal, Adeel; Iqbal, Naseer; Mujahid, Adnan; Schirhagl, Romana

    2013-07-17

    The necessity of selectively detecting various organic vapors is primitive not only with respect to regular environmental and industrial hazard monitoring, but also in detecting explosives to combat terrorism and for defense applications. Today, the huge arsenal of micro-sensors has revolutionized the traditional methods of analysis by, e.g. replacing expensive laboratory equipment, and has made the remote screening of atmospheric threats possible. Surface acoustic wave (SAW) sensors - based on piezoelectric crystal resonators - are extremely sensitive to even very small perturbations in the external atmosphere, because the energy associated with the acoustic waves is confined to the crystal surface. Combined with suitably designed molecular recognition materials SAW devices could develop into highly selective and fast responsive miniaturized sensors, which are capable of continuously monitoring a specific organic gas, preferably in the sub-ppm regime. For this purpose, different types of recognition layers ranging from nanostructured metal oxides and carbons to pristine or molecularly imprinted polymers and self-assembled monolayers have been applied in the past decade. We present a critical review of the recent developments in nano- and micro-engineered synthetic recognition materials predominantly used for SAW-based organic vapor sensors. Besides highlighting their potential to realize real-time vapor sensing, their limitations and future perspectives are also discussed.

  12. Algorithm for heart rate extraction in a novel wearable acoustic sensor

    PubMed Central

    Imtiaz, Syed Anas; Aguilar–Pelaez, Eduardo; Rodriguez–Villegas, Esther

    2015-01-01

    Phonocardiography is a widely used method of listening to the heart sounds and indicating the presence of cardiac abnormalities. Each heart cycle consists of two major sounds – S1 and S2 – that can be used to determine the heart rate. The conventional method of acoustic signal acquisition involves placing the sound sensor at the chest where this sound is most audible. Presented is a novel algorithm for the detection of S1 and S2 heart sounds and the use of them to extract the heart rate from signals acquired by a small sensor placed at the neck. This algorithm achieves an accuracy of 90.73 and 90.69%, with respect to heart rate value provided by two commercial devices, evaluated on more than 38 h of data acquired from ten different subjects during sleep in a pilot clinical study. This is the largest dataset for acoustic heart sound classification and heart rate extraction in the literature to date. The algorithm in this study used signals from a sensor designed to monitor breathing. This shows that the same sensor and signal can be used to monitor both breathing and heart rate, making it highly useful for long-term wearable vital signs monitoring. PMID:26609401

  13. Algorithm for heart rate extraction in a novel wearable acoustic sensor.

    PubMed

    Chen, Guangwei; Imtiaz, Syed Anas; Aguilar-Pelaez, Eduardo; Rodriguez-Villegas, Esther

    2015-02-01

    Phonocardiography is a widely used method of listening to the heart sounds and indicating the presence of cardiac abnormalities. Each heart cycle consists of two major sounds - S1 and S2 - that can be used to determine the heart rate. The conventional method of acoustic signal acquisition involves placing the sound sensor at the chest where this sound is most audible. Presented is a novel algorithm for the detection of S1 and S2 heart sounds and the use of them to extract the heart rate from signals acquired by a small sensor placed at the neck. This algorithm achieves an accuracy of 90.73 and 90.69%, with respect to heart rate value provided by two commercial devices, evaluated on more than 38 h of data acquired from ten different subjects during sleep in a pilot clinical study. This is the largest dataset for acoustic heart sound classification and heart rate extraction in the literature to date. The algorithm in this study used signals from a sensor designed to monitor breathing. This shows that the same sensor and signal can be used to monitor both breathing and heart rate, making it highly useful for long-term wearable vital signs monitoring.

  14. Implementation of Surface Acoustic Wave Vapor Sensor Using Complementary Metal-Oxide-Semiconductor Amplifiers

    NASA Astrophysics Data System (ADS)

    Chiu, Chia-Sung; Chang, Ching-Chun; Ku, Chia-Lin; Peng, Kang-Ming; Jeng, Erik S.; Chen, Wen-Lin; Huang, Guo-Wei; Wu, Lin-Kun

    2009-04-01

    A surface acoustic wave (SAW) vapor sensor is presented in this work. A SAW delay line oscillator on quartz substrate with the high gain complementary metal-oxide-semiconductor (CMOS) amplifier using a two-poly-two-metal (2P2M) 0.35 µm process was designed. The gain of the CMOS amplifier and its total power consumption are 20 dB and 70 mW, respectively. The achieved phase noise of this SAW oscillator is -150 dBc/Hz at 100 kHz offset. The sensing is successfully demonstrated by a thin poly(epichlorohydrin) (PECH) polymer film on a SAW oscillator with alcohol vapor. This two-in-one sensor unit includes the SAW device and the CMOS amplifier provides designers with comprehensive model for using these components for sensor circuit fabrication. Furthermore it will be promising for future chemical and biological sensing applications.

  15. Multiple concurrent sources localization based on a two-node distributed acoustic sensor network

    NASA Astrophysics Data System (ADS)

    Xu, Jiaxin; Zhao, Zhao; Chen, Chunzeng; Xu, Zhiyong

    2017-01-01

    In this work, we propose a new approach to localize multiple concurrent sources using a distributed acoustic sensor network. Only two node-arrays are required in this sensor network, and each node-array consists of only two widely spaced sensors. Firstly, direction-of-arrivals (DOAs) of multiple sources are estimated at each node-array by utilizing a new pooled angular spectrum proposed in this paper, which can implement the spatial aliasing suppression effectively. Based on minimum variance distortionless response (MVDR) beamforming and the DOA estimates of the sources, the time-frequency spectra containing the corresponding energy distribution features associated with those sources are reconstructed in each node-array. Then, scale invariant feature transform (SIFT) is employed to solve the DOA association problem. Performance evaluation is conducted with field recordings and experimental results prove the effectivity and feasibility of the proposed method.

  16. Estimation of the lactate threshold using an electro acoustic sensor system analysing the respiratory air.

    PubMed

    Folke, M

    2008-09-01

    The lactate threshold is used by athletes to optimise the intensity during exercise. It is of interest to measure the threshold on the very day and during the present sport activity. Steady state ergometer tests have been performed on 40 individuals to compare the threshold found by an electro acoustic sensor system to the lactate threshold established by blood analyses evaluated with the Dmax method. The correlation coefficient between the threshold found by the sensor system and the one established by blood analyses regarding workload (Watt), heart rate (beats/min), and lactate level (mmol lactate/l blood) at the thresholds were 0.87 (p < 0.001), 0.74 (p < 0.001), and 0.65 (p < 0.001), respectively. The findings in this study indicates that the thresholds of individuals measured by the sensor system show good correlations to the threshold established with the Dmax method from lactate levels in blood samples.

  17. Theoretical investigation of conductivity sensitivities of SiC-based bio-chemical acoustic wave sensors

    NASA Astrophysics Data System (ADS)

    Fan, Li; Chen, Zhe; Zhang, Shu-yi; Zhang, Hui

    2014-02-01

    The phase velocities, electromechanical coupling coefficients, conductivity sensitivities, insert losses, and minimum detectable masses of Rayleigh and Lamb waves sensors based on silicon carbide (SiC) substrates are theoretically studied. The results are compared with the performances of the sensors based on conventional silicon substrates. It is found that the sensors using SiC substrates have higher electromechanical coupling coefficients and conductivity sensitivities than the conventional silicon-based sensors in virtue of piezoelectricity of the SiC. Moreover, higher phase velocities in SiC substrates can reduce the insert losses and minimum detectable masses of the sensors. In this case, in the detection of the gas with the tiny mass as the hydrogen, in which the conductivity sensitivity is more important than the mass sensitivity, the sensor based on the SiC substrate has a higher sensitivity and exhibits the potential to detect the gas with the concentration below the ppm level. According to the results, the performances of the sensors based on the Rayleigh and Lamb waves using the SiC substrates can be optimized by properly selecting piezoelectric films, structural parameters, and operating wavelengths.

  18. Maximization of the supportable number of sensors in QoS-aware cluster-based underwater acoustic sensor networks.

    PubMed

    Nguyen, Thi-Tham; Le, Duc Van; Yoon, Seokhoon

    2014-03-07

    This paper proposes a practical low-complexity MAC (medium access control) scheme for quality of service (QoS)-aware and cluster-based underwater acoustic sensor networks (UASN), in which the provision of differentiated QoS is required. In such a network, underwater sensors (U-sensor) in a cluster are divided into several classes, each of which has a different QoS requirement. The major problem considered in this paper is the maximization of the number of nodes that a cluster can accommodate while still providing the required QoS for each class in terms of the PDR (packet delivery ratio). In order to address the problem, we first estimate the packet delivery probability (PDP) and use it to formulate an optimization problem to determine the optimal value of the maximum packet retransmissions for each QoS class. The custom greedy and interior-point algorithms are used to find the optimal solutions, which are verified by extensive simulations. The simulation results show that, by solving the proposed optimization problem, the supportable number of underwater sensor nodes can be maximized while satisfying the QoS requirements for each class.

  19. Maximization of the Supportable Number of Sensors in QoS-Aware Cluster-Based Underwater Acoustic Sensor Networks

    PubMed Central

    Nguyen, Thi-Tham; Van Le, Duc; Yoon, Seokhoon

    2014-01-01

    This paper proposes a practical low-complexity MAC (medium access control) scheme for quality of service (QoS)-aware and cluster-based underwater acoustic sensor networks (UASN), in which the provision of differentiated QoS is required. In such a network, underwater sensors (U-sensor) in a cluster are divided into several classes, each of which has a different QoS requirement. The major problem considered in this paper is the maximization of the number of nodes that a cluster can accommodate while still providing the required QoS for each class in terms of the PDR (packet delivery ratio). In order to address the problem, we first estimate the packet delivery probability (PDP) and use it to formulate an optimization problem to determine the optimal value of the maximum packet retransmissions for each QoS class. The custom greedy and interior-point algorithms are used to find the optimal solutions, which are verified by extensive simulations. The simulation results show that, by solving the proposed optimization problem, the supportable number of underwater sensor nodes can be maximized while satisfying the QoS requirements for each class. PMID:24608009

  20. Surface acoustic wave ammonia sensor based on ZnO/SiO2 composite film.

    PubMed

    Wang, Shuang-Yue; Ma, Jin-Yi; Li, Zhi-Jie; Su, H Q; Alkurd, N R; Zhou, Wei-Lie; Wang, Lu; Du, Bo; Tang, Yong-Liang; Ao, Dong-Yi; Zhang, Shou-Chao; Yu, Q K; Zu, Xiao-Tao

    2015-03-21

    A surface acoustic wave (SAW) resonator with ZnO/SiO2 (ZS) composite film was used as an ammonia sensor in this study. ZS composite films were deposited on the surface of SAW devices using the sol-gel method, and were characterized using SEM, AFM, and XRD. The performance of the sensors under ammonia gas was optimized by adjusting the molar ratio of ZnO:SiO2 to 1:1, 1:2 and 1:3, and the sensor with the ratio of ZnO to SiO2 equaling to 1:2 was found to have the best performance. The response of sensor was 1.132 kHz under 10 ppm NH3, which was much higher than that of the sensor based on a pristine ZnO film. Moreover, the sensor has good selectivity, reversibility and stability at room temperature. These can be attributed to the enhanced absorption of ammonia and unique surface reaction on composite films due to the existence of silica.

  1. Probabilistic Neighborhood-Based Data Collection Algorithms for 3D Underwater Acoustic Sensor Networks

    PubMed Central

    Han, Guangjie; Li, Shanshan; Zhu, Chunsheng; Jiang, Jinfang; Zhang, Wenbo

    2017-01-01

    Marine environmental monitoring provides crucial information and support for the exploitation, utilization, and protection of marine resources. With the rapid development of information technology, the development of three-dimensional underwater acoustic sensor networks (3D UASNs) provides a novel strategy to acquire marine environment information conveniently, efficiently and accurately. However, the specific propagation effects of acoustic communication channel lead to decreased successful information delivery probability with increased distance. Therefore, we investigate two probabilistic neighborhood-based data collection algorithms for 3D UASNs which are based on a probabilistic acoustic communication model instead of the traditional deterministic acoustic communication model. An autonomous underwater vehicle (AUV) is employed to traverse along the designed path to collect data from neighborhoods. For 3D UASNs without prior deployment knowledge, partitioning the network into grids can allow the AUV to visit the central location of each grid for data collection. For 3D UASNs in which the deployment knowledge is known in advance, the AUV only needs to visit several selected locations by constructing a minimum probabilistic neighborhood covering set to reduce data latency. Otherwise, by increasing the transmission rounds, our proposed algorithms can provide a tradeoff between data collection latency and information gain. These algorithms are compared with basic Nearest-neighbor Heuristic algorithm via simulations. Simulation analyses show that our proposed algorithms can efficiently reduce the average data collection completion time, corresponding to a decrease of data latency. PMID:28208735

  2. Probabilistic Neighborhood-Based Data Collection Algorithms for 3D Underwater Acoustic Sensor Networks.

    PubMed

    Han, Guangjie; Li, Shanshan; Zhu, Chunsheng; Jiang, Jinfang; Zhang, Wenbo

    2017-02-08

    Marine environmental monitoring provides crucial information and support for the exploitation, utilization, and protection of marine resources. With the rapid development of information technology, the development of three-dimensional underwater acoustic sensor networks (3D UASNs) provides a novel strategy to acquire marine environment information conveniently, efficiently and accurately. However, the specific propagation effects of acoustic communication channel lead to decreased successful information delivery probability with increased distance. Therefore, we investigate two probabilistic neighborhood-based data collection algorithms for 3D UASNs which are based on a probabilistic acoustic communication model instead of the traditional deterministic acoustic communication model. An autonomous underwater vehicle (AUV) is employed to traverse along the designed path to collect data from neighborhoods. For 3D UASNs without prior deployment knowledge, partitioning the network into grids can allow the AUV to visit the central location of each grid for data collection. For 3D UASNs in which the deployment knowledge is known in advance, the AUV only needs to visit several selected locations by constructing a minimum probabilistic neighborhood covering set to reduce data latency. Otherwise, by increasing the transmission rounds, our proposed algorithms can provide a tradeoff between data collection latency and information gain. These algorithms are compared with basic Nearest-neighbor Heuristic algorithm via simulations. Simulation analyses show that our proposed algorithms can efficiently reduce the average data collection completion time, corresponding to a decrease of data latency.

  3. Estimating cetacean population density using fixed passive acoustic sensors: an example with Blainville's beaked whales.

    PubMed

    Marques, Tiago A; Thomas, Len; Ward, Jessica; DiMarzio, Nancy; Tyack, Peter L

    2009-04-01

    Methods are developed for estimating the size/density of cetacean populations using data from a set of fixed passive acoustic sensors. The methods convert the number of detected acoustic cues into animal density by accounting for (i) the probability of detecting cues, (ii) the rate at which animals produce cues, and (iii) the proportion of false positive detections. Additional information is often required for estimation of these quantities, for example, from an acoustic tag applied to a sample of animals. Methods are illustrated with a case study: estimation of Blainville's beaked whale density over a 6 day period in spring 2005, using an 82 hydrophone wide-baseline array located in the Tongue of the Ocean, Bahamas. To estimate the required quantities, additional data are used from digital acoustic tags, attached to five whales over 21 deep dives, where cues recorded on some of the dives are associated with those received on the fixed hydrophones. Estimated density was 25.3 or 22.5 animals/1000 km(2), depending on assumptions about false positive detections, with 95% confidence intervals 17.3-36.9 and 15.4-32.9. These methods are potentially applicable to a wide variety of marine and terrestrial species that are hard to survey using conventional visual methods.

  4. Distributed Capacitive Sensor for Sample Mass Measurement

    NASA Technical Reports Server (NTRS)

    Toda, Risaku; McKinney, Colin; Jackson, Shannon P.; Mojarradi, Mohammad; Manohara, Harish; Trebi-Ollennu, Ashitey

    2011-01-01

    Previous robotic sample return missions lacked in situ sample verification/ quantity measurement instruments. Therefore, the outcome of the mission remained unclear until spacecraft return. In situ sample verification systems such as this Distributed Capacitive (DisC) sensor would enable an unmanned spacecraft system to re-attempt the sample acquisition procedures until the capture of desired sample quantity is positively confirmed, thereby maximizing the prospect for scientific reward. The DisC device contains a 10-cm-diameter pressure-sensitive elastic membrane placed at the bottom of a sample canister. The membrane deforms under the weight of accumulating planetary sample. The membrane is positioned in close proximity to an opposing rigid substrate with a narrow gap. The deformation of the membrane makes the gap narrower, resulting in increased capacitance between the two parallel plates (elastic membrane and rigid substrate). C-V conversion circuits on a nearby PCB (printed circuit board) provide capacitance readout via LVDS (low-voltage differential signaling) interface. The capacitance method was chosen over other potential approaches such as the piezoelectric method because of its inherent temperature stability advantage. A reference capacitor and temperature sensor are embedded in the system to compensate for temperature effects. The pressure-sensitive membranes are aluminum 6061, stainless steel (SUS) 403, and metal-coated polyimide plates. The thicknesses of these membranes range from 250 to 500 m. The rigid substrate is made with a 1- to 2-mm-thick wafer of one of the following materials depending on the application requirements glass, silicon, polyimide, PCB substrate. The glass substrate is fabricated by a microelectromechanical systems (MEMS) fabrication approach. Several concentric electrode patterns are printed on the substrate. The initial gap between the two plates, 100 m, is defined by a silicon spacer ring that is anodically bonded to the glass

  5. An electronic-nose sensor node based on a polymer-coated surface acoustic wave array for wireless sensor network applications.

    PubMed

    Tang, Kea-Tiong; Li, Cheng-Han; Chiu, Shih-Wen

    2011-01-01

    This study developed an electronic-nose sensor node based on a polymer-coated surface acoustic wave (SAW) sensor array. The sensor node comprised an SAW sensor array, a frequency readout circuit, and an Octopus II wireless module. The sensor array was fabricated on a large K(2) 128° YX LiNbO3 sensing substrate. On the surface of this substrate, an interdigital transducer (IDT) was produced with a Cr/Au film as its metallic structure. A mixed-mode frequency readout application specific integrated circuit (ASIC) was fabricated using a TSMC 0.18 μm process. The ASIC output was connected to a wireless module to transmit sensor data to a base station for data storage and analysis. This sensor node is applicable for wireless sensor network (WSN) applications.

  6. Acoustic-wave sensor apparatus for analyzing a petroleum-based composition and sensing solidification of constituents therein

    DOEpatents

    Spates, J.J.; Martin, S.J.; Mansure, A.J.

    1997-08-26

    An acoustic-wave sensor apparatus and method are disclosed. The apparatus for analyzing a normally liquid petroleum-based composition includes at least one acoustic-wave device in contact with the petroleum-based composition for sensing or detecting the presence of constituents (e.g. paraffins or petroleum waxes) therein which solidify upon cooling of the petroleum-based composition below a cloud-point temperature. The acoustic-wave device can be a thickness-shear-mode device (also termed a quartz crystal microbalance), a surface-acoustic-wave device, an acoustic-plate-mode device or a flexural plate-wave device. Embodiments of the present invention can be used for measuring a cloud point, a pour point and/or a freeze point of the petroleum-based composition, and for determining a temperature characteristic of each point. Furthermore, measurements with the acoustic-wave sensor apparatus can be made off-line by using a sample having a particular petroleum-based composition; or in-situ with the petroleum-based composition contained within a pipeline or storage tank. The acoustic-wave sensor apparatus has uses in many different petroleum technology areas, including the recovery, transport, storage, refining and use of petroleum and petroleum-based products. 7 figs.

  7. Acoustic-wave sensor apparatus for analyzing a petroleum-based composition and sensing solidification of constituents therein

    DOEpatents

    Spates, James J.; Martin, Stephen J.; Mansure, Arthur J.

    1997-01-01

    An acoustic-wave sensor apparatus and method. The apparatus for analyzing a normally liquid petroleum-based composition includes at least one acoustic-wave device in contact with the petroleum-based composition for sensing or detecting the presence of constituents (e.g. paraffins or petroleum waxes) therein which solidify upon cooling of the petroleum-based composition below a cloud-point temperature. The acoustic-wave device can be a thickness-shear-mode device (also termed a quartz crystal mircrobalance), a surface-acoustic-wave device, an acoustic-plate-mode device or a flexural plate-wave device. Embodiments of the present invention can be used for measuring a cloud point, a pour point and/or a freeze point of the petroleum-based composition, and for determining a temperature characteristic of each point. Furthermore, measurements with the acoustic-wave sensor apparatus can be made off-line by using a sample having a particular petroleum-based composition; or in-situ with the petroleum-based composition contained within a pipeline or storage tank. The acoustic-wave sensor apparatus has uses in many different petroleum technology areas, including the recover transport, storage, refining and use of petroleum and petroleum-based products.

  8. Acoustic time delay estimation and sensor network self-localization: Experimental results

    NASA Astrophysics Data System (ADS)

    Ash, Joshua N.; Moses, Randolph L.

    2005-08-01

    Experimental results are presented on propagation, coherence, and time-delay estimation (TDE) from a microphone array in an outdoor aeroacoustic environment. The primary goal is to understand the achievable accuracy of acoustic TDE using low-cost, commercial off-the-shelf (COTS) speakers and microphones. In addition, through the use of modulated pseudo-noise sequences, the experiment seeks to provide an empirical understanding of the effects of center frequency, bandwidth, and signal duration on TDE effectiveness and compares this to the theoretical expectations established by the Weiss-Weinstein lower bound. Finally, sensor network self-localization is performed using a maximum likelihood estimator and the time-delay estimates. Experimental network localization error is presented as a function of the acoustic calibration signal parameters.

  9. A non-resonant mass sensor to eliminate the "missing mass" effect during mass measurement of biological materials

    NASA Astrophysics Data System (ADS)

    Shrikanth, V.; Bobji, M. S.

    2014-10-01

    Resonant sensors and crystal oscillators for mass detection need to be excited at very high natural frequencies (MHz). Use of such systems to measure mass of biological materials affects the accuracy of mass measurement due to their viscous and/or viscoelastic properties. The measurement limitation of such sensor system is the difficulty in accounting for the "missing mass" of the biological specimen in question. A sensor system has been developed in this work, to be operated in the stiffness controlled region at very low frequencies as compared to its fundamental natural frequency. The resulting reduction in the sensitivity due to non-resonant mode of operation of this sensor is compensated by the high resolution of the sensor. The mass of different aged drosophila melanogaster (fruit fly) is measured. The difference in its mass measurement during resonant mode of operation is also presented. That, viscosity effects do not affect the working of this non-resonant mass sensor is clearly established by direct comparison.

  10. A non-resonant mass sensor to eliminate the "missing mass" effect during mass measurement of biological materials.

    PubMed

    Shrikanth, V; Bobji, M S

    2014-10-01

    Resonant sensors and crystal oscillators for mass detection need to be excited at very high natural frequencies (MHz). Use of such systems to measure mass of biological materials affects the accuracy of mass measurement due to their viscous and/or viscoelastic properties. The measurement limitation of such sensor system is the difficulty in accounting for the "missing mass" of the biological specimen in question. A sensor system has been developed in this work, to be operated in the stiffness controlled region at very low frequencies as compared to its fundamental natural frequency. The resulting reduction in the sensitivity due to non-resonant mode of operation of this sensor is compensated by the high resolution of the sensor. The mass of different aged drosophila melanogaster (fruit fly) is measured. The difference in its mass measurement during resonant mode of operation is also presented. That, viscosity effects do not affect the working of this non-resonant mass sensor is clearly established by direct comparison.

  11. Optimization of Capacitive Acoustic Resonant Sensor Using Numerical Simulation and Design of Experiment

    PubMed Central

    Haque, Rubaiyet Iftekharul; Loussert, Christophe; Sergent, Michelle; Benaben, Patrick; Boddaert, Xavier

    2015-01-01

    Optimization of the acoustic resonant sensor requires a clear understanding of how the output responses of the sensor are affected by the variation of different factors. During this work, output responses of a capacitive acoustic transducer, such as membrane displacement, quality factor, and capacitance variation, are considered to evaluate the sensor design. The six device parameters taken into consideration are membrane radius, backplate radius, cavity height, air gap, membrane tension, and membrane thickness. The effects of factors on the output responses of the transducer are investigated using an integrated methodology that combines numerical simulation and design of experiments (DOE). A series of numerical experiments are conducted to obtain output responses for different combinations of device parameters using finite element methods (FEM). Response surface method is used to identify the significant factors and to develop the empirical models for the output responses. Finally, these results are utilized to calculate the optimum device parameters using multi-criteria optimization with desirability function. Thereafter, the validating experiments are designed and deployed using the numerical simulation to crosscheck the responses. PMID:25894937

  12. Investigation of phononic crystals for dispersive surface acoustic wave ozone sensors

    NASA Astrophysics Data System (ADS)

    Westafer, Ryan S.

    The object of this research was to investigate dispersion in surface phononic crystals (PnCs) for application to a newly developed passive surface acoustic wave (SAW) ozone sensor. Frequency band gaps and slow sound already have been reported for PnC lattice structures. Such engineered structures are often advertised to reduce loss, increase sensitivity, and reduce device size. However, these advances have not yet been realized in the context of surface acoustic wave sensors. In early work, we computed SAW dispersion in patterned surface structures and we confirmed that our finite element computations of SAW dispersion in thin films and in one dimensional surface PnC structures agree with experimental results obtained by laser probe techniques. We analyzed the computations to guide device design in terms of sensitivity and joint spectral operating point. Next we conducted simulations and experiments to determine sensitivity and limit of detection for more conventional dispersive SAW devices and PnC sensors. Finally, we conducted extensive ozone detection trials on passive reflection mode SAW devices, using distinct components of the time dispersed response to compensate for the effect of temperature. The experimental work revealed that the devices may be used for dosimetry applications over periods of several days.

  13. An Amplitude-Based Estimation Method for International Space Station (ISS) Leak Detection and Localization Using Acoustic Sensor Networks

    NASA Technical Reports Server (NTRS)

    Tian, Jialin; Madaras, Eric I.

    2009-01-01

    The development of a robust and efficient leak detection and localization system within a space station environment presents a unique challenge. A plausible approach includes the implementation of an acoustic sensor network system that can successfully detect the presence of a leak and determine the location of the leak source. Traditional acoustic detection and localization schemes rely on the phase and amplitude information collected by the sensor array system. Furthermore, the acoustic source signals are assumed to be airborne and far-field. Likewise, there are similar applications in sonar. In solids, there are specialized methods for locating events that are used in geology and in acoustic emission testing that involve sensor arrays and depend on a discernable phase front to the received signal. These methods are ineffective if applied to a sensor detection system within the space station environment. In the case of acoustic signal location, there are significant baffling and structural impediments to the sound path and the source could be in the near-field of a sensor in this particular setting.

  14. Bedload transport monitoring with acoustic sensors in the Swiss Albula mountain river

    NASA Astrophysics Data System (ADS)

    Rickenmann, Dieter; Antoniazza, Gilles; Wyss, Carlos R.; Fritschi, Bruno; Boss, Stefan

    2017-03-01

    Bedload transport measurements with acoustic sensors were obtained during summer 2015 in the Albula River in Switzerland. An impact plate measuring system was used with geophone and accelerometer sensors. This system provides indirect estimations of bedload transport in water courses. In April 2015, 30 impact sensors were installed in a new permanent measuring station to monitor continuously bedload transport in a mountain river with a large annual rate of sediment transport (around 90 000 m3 yr-1). Records of the first year of measurement showed that (i) the signal response in terms of geophone and accelerometer impulses is comparable for both types of sensors; (ii) there is a good correlation between discharge data and impulses recorded by both types of sensors; (iii) the critical discharge at the start of bedload transport is around 5 m3 s-1; (iv) a mean calibration factor for the geophone impulses can be estimated which is in a similar range as values determined from other sites with field calibration measurements.

  15. MEMS device for mass market gas and chemical sensors

    NASA Astrophysics Data System (ADS)

    Kinkade, Brian R.; Daly, James T.; Johnson, Edward A.

    2000-08-01

    Gas and chemical sensors are used in many applications. Industrial health and safety monitors allow companies to meet OSHA requirements by detecting harmful levels of toxic or combustible gases. Vehicle emissions are tested during annual inspections. Blood alcohol breathalizers are used by law enforcement. Refrigerant leak detection ensures that the Earth's ozone layer is not being compromised. Industrial combustion emissions are also monitored to minimize pollution. Heating and ventilation systems watch for high levels of carbon dioxide (CO2) to trigger an increase in fresh air exchange. Carbon monoxide detectors are used in homes to prevent poisoning from poor combustion ventilation. Anesthesia gases are monitored during a patients operation. The current economic reality is that two groups of gas sensor technologies are competing in two distinct existing market segments - affordable (less reliable) chemical reaction sensors for consumer markets and reliable (expensive) infrared (IR) spectroscopic sensors for industrial, laboratory, and medical instrumentation markets. Presently high volume mass-market applications are limited to CO detectros and on-board automotive emissions sensors. Due to reliability problems with electrochemical sensor-based CO detectors there is a hesitancy to apply these sensors in other high volume applications. Applications such as: natural gas leak detection, non-invasive blood glucose monitoring, home indoor air quality, personal/portable air quality monitors, home fire/burnt cooking detector, and home food spoilage detectors need a sensor that is a small, efficient, accurate, sensitive, reliable, and inexpensive. Connecting an array of these next generation gas sensors to wireless networks that are starting to proliferate today creates many other applications. Asthmatics could preview the air quality of their destinations as they venture out into the day. HVAC systems could determine if fresh air intake was actually better than the air

  16. Enhanced sensitive love wave surface acoustic wave sensor designed for immunoassay formats.

    PubMed

    Puiu, Mihaela; Gurban, Ana-Maria; Rotariu, Lucian; Brajnicov, Simona; Viespe, Cristian; Bala, Camelia

    2015-05-05

    We report a Love wave surface acoustic wave (LW-SAW) immunosensor designed for the detection of high molecular weight targets in liquid samples, amenable also for low molecular targets in surface competition assays. We implemented a label-free interaction protocol similar to other surface plasmon resonance bioassays having the advantage of requiring reduced time analysis. The fabricated LW-SAW sensor supports the detection of the target in the nanomolar range, and can be ultimately incorporated in portable devices, suitable for point-of-care testing (POCT) applications.

  17. Development of an acoustic sensor for the future IceCube-Gen2 detector for neutrino detection and position calibration

    NASA Astrophysics Data System (ADS)

    Wickmann, Stefan; Eliseev, Dmitry; Heinen, Dirk; Linder, Peter; Rongen, Martin; Scholz, Franziska; Weinstock, Lars Steffen; Wiebusch, Christopher; Zierke, Simon

    2017-03-01

    For the planned high-energy extension of the IceCube Neutrino Observatory in the glacial ice at the South Pole the spacing of detector modules will be increased with respect to IceCube. Because of these larger distances the quality of the geometry calibration based on pulsed light sources is expected to deteriorate. To counter this an independent acoustic geometry calibration system based on trilateration is introduced. Such an acoustic positioning system (APS) has already been developed for the Enceladus Explorer Project (EnEx), initiated by the DLR Space Administration. In order to integrate such APS-sensors into the IceCube detector the power consumption needs to be minimized. In addition, the frequency response of the front end electronics is optimized for positioning as well as the acoustic detection of neutrinos. The new design of the acoustic sensor and results of test measurements with an IceCube detector module will be presented.

  18. A new sparse design method on phased array-based acoustic emission sensor for partial discharge detection

    NASA Astrophysics Data System (ADS)

    Xie, Qing; Cheng, Shuyi; Lü, Fangcheng; Li, Yanqing

    2014-03-01

    The acoustic detecting performance of a partial discharge (PD) ultrasonic sensor array can be improved by increasing the number of array elements. However, it will increase the complexity and cost of the PD detection system. Therefore, a sparse sensor with an optimization design can be chosen to ensure good acoustic performance. In this paper, first, a quantitative method is proposed for evaluating the acoustic performance of a square PD ultrasonic array sensor. Second, a method of sparse design is presented to combine the evaluation method with the chaotic monkey algorithm. Third, an optimal sparse structure of a 3 × 3 square PD ultrasonic array sensor is deduced. It is found that, under different sparseness and sparse structure, the main beam width of the directivity function shows a small variation, while the sidelobe amplitude shows a bigger variation. For a specific sparseness, the acoustic performance under the optimal sparse structure is close to that using a full array. Finally, some simulations based on the above method show that, for certain sparseness, the sensor with the optimal sparse structure exhibits superior positioning accuracy compared to that with a stochastic one. The sensor array structure may be chosen according to the actual requirements for an actual engineering application.

  19. Detection of cells captured with antigens on shear horizontal surface-acoustic-wave sensors.

    PubMed

    Hao, Hsu-Chao; Chang, Hwan-You; Wang, Tsung-Pao; Yao, Da-Jeng

    2013-02-01

    Techniques to separate cells are widely applied in immunology. The technique to separate a specific antigen on a microfluidic platform involves the use of a shear horizontal surface-acoustic-wave (SH-SAW) sensor. With specific antibodies conjugated onto the surface of the SH-SAW sensors, this technique can serve to identify specific cells in bodily fluids. Jurkat cells, used as a target in this work, provide a model of cells in small abundance (1:1000) for isolation and purification with the ultimate goal of targeting even more dilute cells. T cells were separated from a mixed-cell medium on a chip (Jurkat cells/K562 cells, 1/1000). A novel microchamber was developed to capture cells during the purification, which required a large biosample. Cell detection was demonstrated through the performance of genetic identification on the chip.

  20. Above-ground and in situ field screening of VOCs using portable acoustic wave sensor (PAWS) systems

    SciTech Connect

    Frye, G.C.; Cernosek, R.W.; Steinfort, T.D.; Gilbert, D.W.; Colburn, C.

    1995-12-31

    PAWS systems have been developed for real-time, on-line and in situ monitoring of volatile organic compounds (VOCs). These systems utilize the high sensitivity of surface acoustic wave (SAW) devices to changes in the mass or other physical properties of a film cast onto the device surface. Using thin polymer films that rapidly (few seconds) and reversibly absorb the chemical species of interest, these sensors can be used to detect and monitor a wide range of VOCs. Current minimum detection levels range from about 1 to 10 ppm for typical VOCs in a real-time mode and, by incorporating an adsorbent preconcentrator, periodic (every few minutes) analysis down to the 10--100 ppb range, even in the presence of high concentrations of corrosive vapors, can be achieved. Sensor responses are reproducible, leading to accurate measurements, and the devices can operate over a wide concentration range. Above ground and down-hole systems have been demonstrated at environmental restoration sites for: (1) on-line monitoring of off-gas streams from soil vapor extractions, (2) real-time analysis of gas samples pulled to the surface from a cone penetrometer probe, and (3) in situ monitoring of contaminants in vadose zone monitoring wells.

  1. Above-ground and in situ field screening of VOCs using Portable Acoustic Wave Sensor (PAWS) systems

    SciTech Connect

    Frye, G.C.; Cernosek, R.W.; Steinfort, T.D.; Gilbert, D.W.; Colburn, C.

    1995-05-01

    PAWS systems have been developed for real-time, on-line and in situ monitoring of volatile organic compounds (VOCs). These systems utilize the high sensitivity of surface acoustic wave (SAW) devices to changes in the mass or other physical properties of a film cast onto the device surface. Using thin polymer films that rapidly (few seconds) and reversibly absorb the chemical species of interest, these sensors can be used to detect and monitor a wide range of VOCs. Current minimum detection levels range from about 1 to 10 ppm for typical VOCs in a real-time mode and, by incorporating an adsorbent preconcentrator, periodic (every few minutes) analysis down to the 10 - 100 ppb range, even in the presence of high concentrations of corrosive vapors, can be achieved. Sensor responses are reproducible, leading to accurate measurements, and the devices can operate over a wide concentration range. Above ground and down-hole systems have been demonstrated at environmental restoration sites for: (1) on-line monitoring of off-gas streams from soil vapor extractions, (2) real-time analysis of gas samples pulled to the surface from a cone penetrometer probe, and (3) in situ monitoring of contaminants in vadose zone monitoring wells.

  2. First-Order Acoustic Wave Equation Reverse Time Migration Based on the Dual-Sensor Seismic Acquisition System

    NASA Astrophysics Data System (ADS)

    You, Jiachun; Liu, Xuewei; Wu, Ru-Shan

    2017-03-01

    We analyze the mathematical requirements for conventional reverse time migration (RTM) and summarize their rationale. The known information provided by current acquisition system is inadequate for the second-order acoustic wave equations. Therefore, we introduce a dual-sensor seismic acquisition system into the coupled first-order acoustic wave equations. We propose a new dual-sensor reverse time migration called dual-sensor RTM, which includes two input variables, the pressure and vertical particle velocity data. We focus on the performance of dual-sensor RTM in estimating reflection coefficients compared with conventional RTM. Synthetic examples are used for the study of estimating coefficients of reflectors with both dual-sensor RTM and conventional RTM. The results indicate that dual-sensor RTM with two inputs calculates amplitude information more accurately and images structural positions of complex substructures, such as the Marmousi model, more clearly than that of conventional RTM. This shows that the dual-sensor RTM has better accuracy in backpropagation and carries more information in the directivity because of particle velocity injection. Through a simple point-shape model, we demonstrate that dual-sensor RTM decreases the effect of multi-pathing of propagating waves, which is helpful for focusing the energy. In addition, compared to conventional RTM, dual-sensor RTM does not cause extra memory costs. Dual-sensor RTM is, therefore, promising for the computation of multi-component seismic data.

  3. Aircraft IR/acoustic detection evaluation. Volume 2: Development of a ground-based acoustic sensor system for the detection of subsonic jet-powered aircraft

    NASA Technical Reports Server (NTRS)

    Kraft, Robert E.

    1992-01-01

    The design and performance of a ground-based acoustic sensor system for the detection of subsonic jet-powered aircraft is described and specified. The acoustic detection system performance criteria will subsequently be used to determine target detection ranges for the subject contract. Although the defined system has never been built and demonstrated in the field, the design parameters were chosen on the basis of achievable technology and overall system practicality. Areas where additional information is needed to substantiate the design are identified.

  4. Experimental study on acoustic subwavelength imaging based on zero-mass metamaterials

    NASA Astrophysics Data System (ADS)

    Xu, Xianchen; Li, Pei; Zhou, Xiaoming; Hu, Gengkai

    2015-01-01

    Anisotropic zero-mass acoustic metamaterials are able to transmit evanescent waves without decaying to a far distance, and have been used for near-field acoustic subwavelength imaging. In this work, we design and fabricate such metamaterial lens based on clamped paper membrane units. The zero-mass frequency is determined by normal-incidence acoustic transmission measurement. At this frequency, we verify in experiment that the fabricated metamaterial lens is able to distinguish clearly two sound sources separated with a distance 0.16λ0 (λ0 is the wavelength in air) below the diffraction limit. We also demonstrate that the imaging frequency is invariant to the change of the lens thickness.

  5. Practical acoustic thermometry with twin-tube and single-tube sensors

    SciTech Connect

    De Podesta, M.; Sutton, G.; Edwards, G.; Stanger, L.; Preece, H.

    2015-07-01

    Accurate measurement of high temperatures in a nuclear environment presents unique challenges. All secondary techniques inevitably drift because the thermometric materials in thermocouples and resistance sensors are sensitive not just to temperature, but also their own chemical and physical composition. The solution is to use primary methods that rely on fundamental links between measurable physical properties and temperature. In the nuclear field the best known technique is the measurement of Johnson Noise in a resistor (See Paper 80 at this conference). In this paper we describe the measurement of temperature in terms of the speed of sound in a gas confined in a tube - an acoustic waveguide. Acoustic thermometry is the most accurate technique of primary thermometry ever devised with the best uncertainty of measurement below 0.001 C. In contrast, the acoustic technique described in this work has a much larger uncertainty, approximately 1 deg. C. But the cost and ease of use are improved by several orders of magnitude, making implementation eminently practical. We first describe the basic construction and method of operation of thermometers using twin-tubes and single tubes. We then present results using a twin-tube design showing that showing long term stability (i.e. no detectable drift) at 700 deg. C over periods of several weeks. We then outline how the technique may be developed for different nuclear applications. (authors)

  6. Transparent ZnO/glass surface acoustic wave based high performance ultraviolet light sensors

    NASA Astrophysics Data System (ADS)

    Wang, Wen-Bo; Gu, Hang; He, Xing-Li; Xuan, Wei-Peng; Chen, Jin-Kai; Wang, Xiao-Zhi; Luo, Ji-Kui

    2015-05-01

    Surface acoustic wave (SAW) resonators are a type of ultraviolet (UV) light sensors with high sensitivity, and they have been extensively studied. Transparent SAW devices are very useful and can be developed into various sensors and microfluidics for sensing/monitoring and lab-on-chip applications. We report the fabrication of high sensitivity SAW UV sensors based on piezoelectric (PE) ZnO thin films deposited on glass substrates. The sensors were fabricated and their performances against the post-deposition annealing condition were investigated. It was found that the UV-light sensitivity is improved by more than one order of magnitude after annealing. The frequency response increases significantly and the response becomes much faster. The optimized devices also show a small temperature coefficient of frequency and excellent repeatability and stability, demonstrating its potential for UV-light sensing application. Project supported by the National Natural Science Foundation of China (Grant Nos. 61274037 and 61301046) and the Research Fund for the Doctoral Program of Higher Education of China (Grant Nos. 20120101110031 and 20120101110054).

  7. Acoustic emission detection with fiber optical sensors for dry cask storage health monitoring

    NASA Astrophysics Data System (ADS)

    Lin, Bin; Bao, Jingjing; Yu, Lingyu; Giurgiutiu, Victor

    2016-04-01

    The increasing number, size, and complexity of nuclear facilities deployed worldwide are increasing the need to maintain readiness and develop innovative sensing materials to monitor important to safety structures (ITS). In the past two decades, an extensive sensor technology development has been used for structural health monitoring (SHM). Technologies for the diagnosis and prognosis of a nuclear system, such as dry cask storage system (DCSS), can improve verification of the health of the structure that can eventually reduce the likelihood of inadvertently failure of a component. Fiber optical sensors have emerged as one of the major SHM technologies developed particularly for temperature and strain measurements. This paper presents the development of optical equipment that is suitable for ultrasonic guided wave detection for active SHM in the MHz range. An experimental study of using fiber Bragg grating (FBG) as acoustic emission (AE) sensors was performed on steel blocks. FBG have the advantage of being durable, lightweight, and easily embeddable into composite structures as well as being immune to electromagnetic interference and optically multiplexed. The temperature effect on the FBG sensors was also studied. A multi-channel FBG system was developed and compared with piezoelectric based AE system. The paper ends with conclusions and suggestions for further work.

  8. Estimation of respiratory rate and heart rate during treadmill tests using acoustic sensor.

    PubMed

    Popov, B; Sierra, G; Telfort, V; Agarwal, R; Lanzo, V

    2005-01-01

    The objective was to test the robustness of an acoustic method to estimate respiratory rates (RR) during treadmill test. The accuracy was assessed by the comparison with simultaneous estimates from a capnograph, using as a common reference a pneumotachometer. Eight subjects without any pulmonary disease were enrolled. Tracheal sounds were acquired using a contact piezoelectric sensor placed on the subject's throat and analyzed using a combined investigation of the sound envelope and frequency content. The capnograph and pneumotachometer were coupled to a face mask worn by the subjects. There was a strong linear correlation between all three methods (r2ranged from 0.8 to 0.87), and the SEE ranged from 1.97 to 2.36. As a conclusion, the accuracy of the respiratory rate estimated from tracheal sounds on adult subjects during treadmill stress test was comparable to the accuracy of a commercial capnograph. The heart rate (HR) estimates can also be derived from carotid pulse using the same single sensor placed on the subject's throat. Compared to the pulse oximeter the results show an agreement of acoustic method with r2=0.76 and SEE = 3.51.

  9. Visualization of stress wave propagation via air-coupled acoustic emission sensors

    NASA Astrophysics Data System (ADS)

    Rivey, Joshua C.; Lee, Gil-Yong; Yang, Jinkyu; Kim, Youngkey; Kim, Sungchan

    2017-02-01

    We experimentally demonstrate the feasibility of visualizing stress waves propagating in plates using air-coupled acoustic emission sensors. Specifically, we employ a device that embeds arrays of microphones around an optical lens in a helical pattern. By implementing a beamforming technique, this remote sensing system allows us to record wave propagation events in situ via a single-shot and full-field measurement. This is a significant improvement over the conventional wave propagation tracking approaches based on laser doppler vibrometry or digital image correlation techniques. In this paper, we focus on demonstrating the feasibility and efficacy of this air-coupled acoustic emission technique by using large metallic plates exposed to external impacts. The visualization results of stress wave propagation will be shown under various impact scenarios. The proposed technique can be used to characterize and localize damage by detecting the attenuation, reflection, and scattering of stress waves that occurs at damage locations. This can ultimately lead to the development of new structural health monitoring and nondestructive evaluation methods for identifying hidden cracks or delaminations in metallic or composite plate structures, simultaneously negating the need for mounted contact sensors.

  10. Modified Particle Filtering Algorithm for Single Acoustic Vector Sensor DOA Tracking

    PubMed Central

    Li, Xinbo; Sun, Haixin; Jiang, Liangxu; Shi, Yaowu; Wu, Yue

    2015-01-01

    The conventional direction of arrival (DOA) estimation algorithm with static sources assumption usually estimates the source angles of two adjacent moments independently and the correlation of the moments is not considered. In this article, we focus on the DOA estimation of moving sources and a modified particle filtering (MPF) algorithm is proposed with state space model of single acoustic vector sensor. Although the particle filtering (PF) algorithm has been introduced for acoustic vector sensor applications, it is not suitable for the case that one dimension angle of source is estimated with large deviation, the two dimension angles (pitch angle and azimuth angle) cannot be simultaneously employed to update the state through resampling processing of PF algorithm. To solve the problems mentioned above, the MPF algorithm is proposed in which the state estimation of previous moment is introduced to the particle sampling of present moment to improve the importance function. Moreover, the independent relationship of pitch angle and azimuth angle is considered and the two dimension angles are sampled and evaluated, respectively. Then, the MUSIC spectrum function is used as the “likehood” function of the MPF algorithm, and the modified PF-MUSIC (MPF-MUSIC) algorithm is proposed to improve the root mean square error (RMSE) and the probability of convergence. The theoretical analysis and the simulation results validate the effectiveness and feasibility of the two proposed algorithms. PMID:26501280

  11. Lignin Sensor Based On Flash-Pyrolysis Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Kwack, Eug Y.; Lawson, Daniel D.; Shakkottai, Parthasarathy

    1990-01-01

    New lignin sensor takes only few minutes to measure lignin content of specimen of wood, pulp, paper, or similar material. Includes flash pyrolizer and ion-trap detector that acts as mass spectrometer. Apparatus measures amount of molecular fragments of lignin in pyrolysis products of samples. Helpful in controlling digestors in paper mills to maintain required lignin content, and also in bleaching plants, where good control of bleaching becomes possible if quick determination of lignin content made.

  12. Fluid mass sensor for a zero gravity environment

    NASA Technical Reports Server (NTRS)

    Fogal, G. L. (Inventor)

    1976-01-01

    A sensor for measuring the mass of fluids, is described which includes a housing having an inlet and outlet for receiving and dumping the fluid, a rotary impeller within the housing for imparting centrifugal motion to the fluid and a pressure sensitive transducer attached to the housing to sense the rotating fluid pressure. The fluid may be drawn into the housing by entrainment within a gas stream. The resulting mixture is then separated into two phases: gas and liquid. The gas is removed from the housing and the pressure of the liquid, under centrifugal motion, is sensed and correlated with the mass of the fluid.

  13. Ultrasensitive nanomechanical mass sensor using hybrid opto-electromechanical systems.

    PubMed

    Jiang, Cheng; Cui, Yuanshun; Zhu, Ka-Di

    2014-06-02

    Nanomechanical resonators provide an unparalleled mass sensitivity sufficient to detect single biomolecules, viruses and nanoparticles. In this work we propose a scheme for mass sensing based on the hybrid opto-electromechanical system, where a mechanical resonator is coupled to an optical cavity and a microwave cavity simultaneously. When the two cavities are driven by two pump fields with proper frequencies and powers, a weak probe field is used to scan across the optical cavity resonance frequency. The mass of a single baculovirus landing onto the surface of the mechanical resonator can be measured by tracking the resonance frequency shift in the probe transmission spectrum before and after the deposition. We also propose a nonlinear mass sensor based on the measurement of the four-wave mixing (FWM) spectrum, which can be used to weigh a single 20-nm-diameter gold nanoparticle with sub-femtogram resolution.

  14. Development of an Acoustic Sensor On-Line Gas Temperature Measurement in Gasifiers

    SciTech Connect

    Peter Ariessohn

    2008-06-30

    This project was awarded under U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) Program Solicitation DE-PS26-02NT41422 and specifically addresses Technical Topical Area 2 - Gasification Technologies. The project team includes Enertechnix, Inc. as the main contractor and ConocoPhillips Company as a technical partner, who also provides access to the SG Solutions Gasification Facility (formerly Wabash River Energy Limited), host for the field-testing portion of the research. The objective of this project was to adapt acoustic pyrometer technology to make it suitable for measuring gas temperature inside a coal gasifier, to develop a prototype sensor based on this technology, and to demonstrate its performance through testing on a commercial gasifier. The project was organized in three phases, each of approximately one year duration. The first phase consisted of researching a variety of sound generation and coupling approaches suitable for use with a high pressure process, evaluation of the impact of gas composition variability on the acoustic temperature measurement approach, evaluation of the impact of suspended particles and gas properties on sound attenuation, evaluation of slagging issues and development of concepts to deal with this issue, development and testing of key prototype components to allow selection of the best approaches, and development of a conceptual design for a field prototype sensor that could be tested on an operating gasifier. The second phase consisted of designing and fabricating a series of prototype sensors, testing them in the laboratory, and developing a conceptual design for a field prototype sensor. The third phase consisted of designing and fabricating the field prototype, and testing it in the lab and in a commercial gasifier to demonstrate the ability to obtain accurate measurements of gas temperature in an operating gasifier. Following the completion of the initial 3 year project, several continuations

  15. LISST-ABS: A Low-Cost Submersible Acoustic Sediment Sensor

    NASA Astrophysics Data System (ADS)

    Slade, W. H.; Agrawal, Y. C.; Dana, D. R.; Leeuw, T.; Pottsmith, C.

    2015-12-01

    The development of low-cost optical sensors (i.e., transmissometers and optical backscattering sensors, OBS) produced the last significant advance in in-situ monitoring of suspended sediment concentration. However, it was well-known from fundamental physics of light scattering and laboratory work, that their response suffered from a severe non-uniformity to grain-size (varying as 1/diameter), susceptibility to biofouling, and limited dynamic range. Here we present the development of a new, low cost, single-point, 8 MHz acoustic backscatter sensor, LISST-ABS that improves on all these shortcomings. For example, the response is nearly flat over 30-400 micron diameters varying within ±30% of the mean (compared with roughly ±400% for OBS over the same size range), fouling is less serious, and the dynamic range spans 5 decades without change of electronic gain. A key innovation of the LISST-ABS is the use of backscatter signal from two range cells in order to measure and compensate for sediment attenuation, allowing a working concentration range exceeding 1 mg/L to 70 g/L (for 7 micron particles).

  16. Acoustic Sensor Planning for Gunshot Location in National Parks: A Pareto Front Approach

    PubMed Central

    González-Castaño, Francisco Javier; Alonso, Javier Vales; Costa-Montenegro, Enrique; López-Matencio, Pablo; Vicente-Carrasco, Francisco; Parrado-García, Francisco J.; Gil-Castiñeira, Felipe; Costas-Rodríguez, Sergio

    2009-01-01

    In this paper, we propose a solution for gunshot location in national parks. In Spain there are agencies such as SEPRONA that fight against poaching with considerable success. The DiANa project, which is endorsed by Cabaneros National Park and the SEPRONA service, proposes a system to automatically detect and locate gunshots. This work presents its technical aspects related to network design and planning. The system consists of a network of acoustic sensors that locate gunshots by hyperbolic multi-lateration estimation. The differences in sound time arrivals allow the computation of a low error estimator of gunshot location. The accuracy of this method depends on tight sensor clock synchronization, which an ad-hoc time synchronization protocol provides. On the other hand, since the areas under surveillance are wide, and electric power is scarce, it is necessary to maximize detection coverage and minimize system cost at the same time. Therefore, sensor network planning has two targets, i.e., coverage and cost. We model planning as an unconstrained problem with two objective functions. We determine a set of candidate solutions of interest by combining a derivative-free descent method we have recently proposed with a Pareto front approach. The results are clearly superior to random seeding in a realistic simulation scenario. PMID:22303135

  17. Acoustic sensor planning for gunshot location in national parks: a pareto front approach.

    PubMed

    González-Castaño, Francisco Javier; Alonso, Javier Vales; Costa-Montenegro, Enrique; López-Matencio, Pablo; Vicente-Carrasco, Francisco; Parrado-García, Francisco J; Gil-Castiñeira, Felipe; Costas-Rodríguez, Sergio

    2009-01-01

    In this paper, we propose a solution for gunshot location in national parks. In Spain there are agencies such as SEPRONA that fight against poaching with considerable success. The DiANa project, which is endorsed by Cabaneros National Park and the SEPRONA service, proposes a system to automatically detect and locate gunshots. This work presents its technical aspects related to network design and planning. The system consists of a network of acoustic sensors that locate gunshots by hyperbolic multi-lateration estimation. The differences in sound time arrivals allow the computation of a low error estimator of gunshot location. The accuracy of this method depends on tight sensor clock synchronization, which an ad-hoc time synchronization protocol provides. On the other hand, since the areas under surveillance are wide, and electric power is scarce, it is necessary to maximize detection coverage and minimize system cost at the same time. Therefore, sensor network planning has two targets, i.e., coverage and cost. We model planning as an unconstrained problem with two objective functions. We determine a set of candidate solutions of interest by combining a derivative-free descent method we have recently proposed with a Pareto front approach. The results are clearly superior to random seeding in a realistic simulation scenario.

  18. New Application of Shear Horizontal Surface Acoustic Wave Sensors to Identifying Fruit Juices

    NASA Astrophysics Data System (ADS)

    Kondoh, Jun; Shiokawa, Showko

    1994-05-01

    The objective of this paper is to present a new application of shear horizontal surface acoustic wave (SH-SAW) devices on 36° rotated Y-cut X-propagating LiTaO3 for a sensing system that can identify liquid samples, such as fruit juices. Theoretical sensor sensitivity for acoustoelectric interaction with a liquid loaded on the SAW propagation surface was derived and confirmed with experimental results. The results strongly suggested that by employing SH-SAW devices with different center frequencies the sensor can recognize many liquid samples without a film coated on the substrate surface. In the experiment, the sensing system which identifies fruit juices was fabricated using three SH-SAW devices with center frequencies of 30, 50, and 100 MHz. Identification of samples, eleven kinds of fruit juices, was achieved by classification in principal component analysis and discriminant analysis. Since the SH-SAW sensor without a coating film has intrinsically good reproducibility and stability, it is effective for identification and quality control of liquid samples.

  19. Enhanced sensitivity of surface acoustic wave-based rate sensors incorporating metallic dot arrays.

    PubMed

    Wang, Wen; Shao, Xiuting; Liu, Xinlu; Liu, Jiuling; He, Shitang

    2014-02-26

    A new surface acoustic wave (SAW)-based rate sensor pattern incorporating metallic dot arrays was developed in this paper. Two parallel SAW delay lines with a reverse direction and an operation frequency of 80 MHz on a same X-112°Y LiTaO3 wafer are fabricated as the feedback of two SAW oscillators, and mixed oscillation frequency was used to characterize the external rotation. To enhance the Coriolis force effect acting on the SAW propagation, a copper (Cu) dot array was deposited along the SAW propagation path of the SAW devices. The approach of partial-wave analysis in layered media was referred to analyze the response mechanisms of the SAW based rate sensor, resulting in determination of the optimal design parameters. To improve the frequency stability of the oscillator, the single phase unidirectional transducers (SPUDTs) and combed transducer were used to form the SAW device to minimize the insertion loss and accomplish the single mode selection, respectively. Excellent long-term (measured in hours) frequency stability of 0.1 ppm/h was obtained. Using the rate table with high precision, the performance of the developed SAW rate sensor was evaluated experimentally; satisfactory detection sensitivity (16.7 Hz∙deg∙s(-1)) and good linearity were observed.

  20. Acoustic emission-based sensor analysis and damage classification for structural health monitoring of composite structures

    NASA Astrophysics Data System (ADS)

    Uprety, Bibhisha

    Within the aerospace industry the need to detect and locate impact events, even when no visible damage is present, is important both from the maintenance and design perspectives. This research focused on the use of Acoustic Emission (AE) based sensing technologies to identify impact events and characterize damage modes in composite structures for structural health monitoring. Six commercially available piezoelectric AE sensors were evaluated for use with impact location estimation algorithms under development at the University of Utah. Both active and passive testing were performed to estimate the time of arrival and plate wave mode velocities for impact location estimation. Four sensors were recommended for further comparative investigations. Furthermore, instrumented low-velocity impact experiments were conducted on quasi-isotropic carbon/epoxy composite laminates to initiate specific types of damage: matrix cracking, delamination and fiber breakage. AE signal responses were collected during impacting and the test panels were ultrasonically C-scanned after impact to identify the internal damage corresponding to the AE signals. Matrix cracking and delamination damage produced using more compliant test panels and larger diameter impactor were characterized by lower frequency signals while fiber breakage produced higher frequency responses. The results obtained suggest that selected characteristics of sensor response signals can be used both to determine whether damage is produced during impacting and to characterize the types of damage produced in an impacted composite structure.

  1. Secure Cooperation of Autonomous Mobile Sensors Using an Underwater Acoustic Network

    PubMed Central

    Caiti, Andrea; Calabrò, Vincenzo; Dini, Gianluca; Duca, Angelica Lo; Munafò, Andrea

    2012-01-01

    Methodologies and algorithms are presented for the secure cooperation of a team of autonomous mobile underwater sensors, connected through an acoustic communication network, within surveillance and patrolling applications. In particular, the work proposes a cooperative algorithm in which the mobile underwater sensors (installed on Autonomous Underwater Vehicles—AUVs) respond to simple local rules based on the available information to perform the mission and maintain the communication link with the network (behavioral approach). The algorithm is intrinsically robust: with loss of communication among the vehicles the coverage performance (i.e., the mission goal) is degraded but not lost. The ensuing form of graceful degradation provides also a reactive measure against Denial of Service. The cooperative algorithm relies on the fact that the available information from the other sensors, though not necessarily complete, is trustworthy. To ensure trustworthiness, a security suite has been designed, specifically oriented to the underwater scenario, and in particular with the goal of reducing the communication overhead introduced by security in terms of number and size of messages. The paper gives implementation details on the integration between the security suite and the cooperative algorithm and provides statistics on the performance of the system as collected during the UAN project sea trial held in Trondheim, Norway, in May 2011. PMID:22438748

  2. Secure cooperation of autonomous mobile sensors using an underwater acoustic network.

    PubMed

    Caiti, Andrea; Calabrò, Vincenzo; Dini, Gianluca; Lo Duca, Angelica; Munafò, Andrea

    2012-01-01

    Methodologies and algorithms are presented for the secure cooperation of a team of autonomous mobile underwater sensors, connected through an acoustic communication network, within surveillance and patrolling applications. In particular, the work proposes a cooperative algorithm in which the mobile underwater sensors (installed on Autonomous Underwater Vehicles-AUVs) respond to simple local rules based on the available information to perform the mission and maintain the communication link with the network (behavioral approach). The algorithm is intrinsically robust: with loss of communication among the vehicles the coverage performance (i.e., the mission goal) is degraded but not lost. The ensuing form of graceful degradation provides also a reactive measure against Denial of Service. The cooperative algorithm relies on the fact that the available information from the other sensors, though not necessarily complete, is trustworthy. To ensure trustworthiness, a security suite has been designed, specifically oriented to the underwater scenario, and in particular with the goal of reducing the communication overhead introduced by security in terms of number and size of messages. The paper gives implementation details on the integration between the security suite and the cooperative algorithm and provides statistics on the performance of the system as collected during the UAN project sea trial held in Trondheim, Norway, in May 2011.

  3. Two clover-shaped piezoresistive silicon microphones for photo acoustic gas sensors

    NASA Astrophysics Data System (ADS)

    Grinde, C.; Sanginario, A.; Ohlckers, P. A.; Jensen, G. U.; Mielnik, M. M.

    2010-04-01

    Low cost CO2 gas sensors for demand-controlled ventilation can lower the energy consumption and increase comfort and hence productivity in office buildings and schools. The photo aoustic principle offers very high sensitivity and selectivity when used for gas trace analysis. Current systems are too expensive and large for in-duct mounting. Here, the design, modeling, fabrication and characterization of two micromachined silicon microphones with piezoresistive readout designed for low cost photo acoustic gas sensors are presented. The microphones have been fabricated using a foundry MPW service. One of the microphones has been fabricated using an additional etching step that allows etching through membranes with large variations in thickness. To increase sensitivity and resolution, a design based on a released membrane suspended by four beams was chosen. The microphones have been characterized for frequencies up to 1 kHz and 100 Hz, respectively. Averaged sensitivities are measured to be 30 µV/(V × Pa) and 400 µV/(V × Pa). The presented microphones offer increased sensitivities compared to similar sensors.

  4. A theoretical study of acoustic glitches in low-mass main-sequence stars

    SciTech Connect

    Verma, Kuldeep; Antia, H. M.; Basu, Sarbani; Mazumdar, Anwesh E-mail: antia@tifr.res.in E-mail: anwesh@tifr.res.in

    2014-10-20

    There are regions in stars, such as ionization zones and the interface between radiative and convective regions, that cause a localized sharp variation in the sound speed. These are known as 'acoustic glitches'. Acoustic glitches leave their signatures on the oscillation frequencies of stars, and hence these signatures can be used as diagnostics of these regions. In particular, the signatures of these glitches can be used as diagnostics for the position of the second helium ionization zone and that of the base of the envelope convection zone. With the help of stellar models, we study the properties of these acoustic glitches in main-sequence stars. We find that the acoustic glitch due to the helium ionization zone does not correspond to the dip in the adiabatic index Γ{sub 1} caused by the ionization of He II, but to the peak in Γ{sub 1} between the He I and He II ionization zones. We find that it is easiest to study the acoustic glitch that is due to the helium ionization zone in stars with masses in the range 0.9-1.2 M {sub ☉}.

  5. Quantitative determination of size and shape of surface-bound DNA using an acoustic wave sensor.

    PubMed

    Tsortos, Achilleas; Papadakis, George; Mitsakakis, Konstantinos; Melzak, Kathryn A; Gizeli, Electra

    2008-04-01

    DNA bending plays a significant role in many biological processes, such as gene regulation, DNA replication, and chromosomal packing. Understanding how such processes take place and how they can, in turn, be regulated by artificial agents for individual oriented therapies is of importance to both biology and medicine. In this work, we describe the application of an acoustic wave device for characterizing the conformation of DNA molecules tethered to the device surface via a biotin-neutravidin interaction. The acoustic energy dissipation per unit mass observed upon DNA binding is directly related to DNA intrinsic viscosity, providing quantitative information on the size and shape of the tethered molecules. The validity of the above approach was verified by showing that the predesigned geometries of model double-stranded and triple-helix DNA molecules could be quantitatively distinguished: the resolution of the acoustic measurements is sufficient to allow discrimination between same size DNA carrying a bent at different positions along the chain. Furthermore, the significance of this analysis to the study of biologically relevant systems is shown during the evaluation of DNA conformational change upon protein (histone) binding.

  6. 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.

  7. The Fractional Free Volume of the Sorbed Vapor in Modeling the Viscoelastic Contribution to Polymer-Coated Surface Acoustic Wave Vapor Sensor Responses

    SciTech Connect

    Grate, Jay W. ); Zellers, Edward T.

    1999-12-01

    Surface acoustic wave (SAW) vapor sensors with polymeric sorbent layers can respond to vapors based on mass-loading and modulus decreases of the polymer film. The modulus changes are associated with volume changes that occur as vapor is sorbed by the film. A factor based on the fractional free volume of the vapor as a liquid has been incorporated into a model for the contribution of swelling-induced modulus changes to observed SAW vapor sensor responses. In this model, it is not the entire volume added to the film by the vapor molecules that causes the modulus to decrease. The free volume effect is calibrated from thermal expansion experiments. The amplification of the SAW vapor sensor response due to modulus effects that are predicted by this model have been compared to amplification factors determined by comparing the responses of polymer-coated SAW vapor sensors with the responses of similarly-coated thickness shear mode (TSM) vapor sensors, the latter being gravimetric. Results for six vapors on each of two polymers, poly(isobutylene) and poly(epichlorohydrin), were examined. The model correctly predicts amplification factors are related to the specific volume of the vapor as a liquid. The fractional free volume factor provides a physically meaningful addition to the model and is consistent with conventional polymer physics treatments of the effects of temperature and plasticization on polymer modulus.

  8. Intensity-demodulated fiber-ring laser sensor system for acoustic emission detection.

    PubMed

    Han, Ming; Liu, Tongqing; Hu, Lingling; Zhang, Qi

    2013-12-02

    We theoretically and experimentally demonstrate a fiber-optic ultrasonic sensor system based on a fiber-ring laser whose cavity consisting of a regular fiber Bragg grating (FBG) and a tunable optical band-pass filter (TOBPF). The FBG is the sensing element and the TOBPF is used to set the lasing wavelength at a point on the spectral slope of the FBG. The ultrasonic signal is detected by the variations of the laser output intensity in response to the cold-cavity loss modulations from the ultrasonically-induced FBG spectral shift. The system demonstrated here has a simple structure and low cost, making it attractive for acoustic emission detection in structure health monitoring.

  9. A Network Coding Based Hybrid ARQ Protocol for Underwater Acoustic Sensor Networks

    PubMed Central

    Wang, Hao; Wang, Shilian; Zhang, Eryang; Zou, Jianbin

    2016-01-01

    Underwater Acoustic Sensor Networks (UASNs) have attracted increasing interest in recent years due to their extensive commercial and military applications. However, the harsh underwater channel causes many challenges for the design of reliable underwater data transport protocol. In this paper, we propose an energy efficient data transport protocol based on network coding and hybrid automatic repeat request (NCHARQ) to ensure reliability, efficiency and availability in UASNs. Moreover, an adaptive window length estimation algorithm is designed to optimize the throughput and energy consumption tradeoff. The algorithm can adaptively change the code rate and can be insensitive to the environment change. Extensive simulations and analysis show that NCHARQ significantly reduces energy consumption with short end-to-end delay. PMID:27618044

  10. Acoustic measurement of sediment dynamics in the coastal zones using wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Sudhakaran, A., II; Paramasivam, A.; Seshachalam, S.; A, C.

    2014-12-01

    Analyzing of the impact of constructive or low energy waves and deconstructive or high energy waves in the ocean are very much significant since they deform the geometry of seashore. The deformation may lead to productive result and also to the end of deteriorate damage. Constructive waves results deposition of sediment which widens the beach where as deconstructive waves results erosion which narrows the beach. Validation of historic sediment transportation and prediction of the direction of movement of seashore is essential to prevent unrecoverable damages by incorporating precautionary measurements to identify the factors that influence sediment transportation if feasible. The objective of this study is to propose a more reliable and energy efficient Information and communication system to model the Coastal Sediment Dynamics. Various factors influencing the sediment drift at a particular region is identified. Consequence of source depth and frequency dependencies of spread pattern in the presence of sediments is modeled. Property of source depth and frequency on sensitivity to values of model parameters are determined. Fundamental physical reasons for these sediment interaction effects are given. Shallow to deep water and internal and external wave model of ocean is obtained intended to get acoustic data assimilation (ADA). Signal processing algorithms are used over the observed data to form a full field acoustic propagation model and construct sound speed profile (SSP). The inversions of data due to uncertainties at various depths are compared. The impact of sediment drift over acoustic data is identified. An energy efficient multipath routing scheme Wireless sensor networks (WSN) is deployed for the well-organized communication of data. The WSN is designed considering increased life time, decreased power consumption, free of threats and attacks. The practical data obtained from the efficient system to model the ocean sediment dynamics are evaluated with remote

  11. Lightweight filter architecture for energy efficient mobile vehicle localization based on a distributed acoustic sensor network.

    PubMed

    Kim, Keonwook

    2013-08-23

    The generic properties of an acoustic signal provide numerous benefits for localization by applying energy-based methods over a deployed wireless sensor network (WSN). However, the signal generated by a stationary target utilizes a significant amount of bandwidth and power in the system without providing further position information. For vehicle localization, this paper proposes a novel proximity velocity vector estimator (PVVE) node architecture in order to capture the energy from a moving vehicle and reject the signal from motionless automobiles around the WSN node. A cascade structure between analog envelope detector and digital exponential smoothing filter presents the velocity vector-sensitive output with low analog circuit and digital computation complexity. The optimal parameters in the exponential smoothing filter are obtained by analytical and mathematical methods for maximum variation over the vehicle speed. For stationary targets, the derived simulation based on the acoustic field parameters demonstrates that the system significantly reduces the communication requirements with low complexity and can be expected to extend the operation time considerably.

  12. Cetacean population density estimation from single fixed sensors using passive acoustics.

    PubMed

    Küsel, Elizabeth T; Mellinger, David K; Thomas, Len; Marques, Tiago A; Moretti, David; Ward, Jessica

    2011-06-01

    Passive acoustic methods are increasingly being used to estimate animal population density. Most density estimation methods are based on estimates of the probability of detecting calls as functions of distance. Typically these are obtained using receivers capable of localizing calls or from studies of tagged animals. However, both approaches are expensive to implement. The approach described here uses a MonteCarlo model to estimate the probability of detecting calls from single sensors. The passive sonar equation is used to predict signal-to-noise ratios (SNRs) of received clicks, which are then combined with a detector characterization that predicts probability of detection as a function of SNR. Input distributions for source level, beam pattern, and whale depth are obtained from the literature. Acoustic propagation modeling is used to estimate transmission loss. Other inputs for density estimation are call rate, obtained from the literature, and false positive rate, obtained from manual analysis of a data sample. The method is applied to estimate density of Blainville's beaked whales over a 6-day period around a single hydrophone located in the Tongue of the Ocean, Bahamas. Results are consistent with those from previous analyses, which use additional tag data.

  13. Micro-electromechanical film bulk acoustic sensor for plasma and whole blood coagulation monitoring.

    PubMed

    Chen, Da; Song, Shuren; Ma, Jilong; Zhang, Zhen; Wang, Peng; Liu, Weihui; Guo, Qiuquan

    2017-05-15

    Monitoring blood coagulation is an important issue in the surgeries and the treatment of cardiovascular diseases. In this work, we reported a novel strategy for the blood coagulation monitoring based on a micro-electromechanical film bulk acoustic resonator. The resonator was excited by a lateral electric field and operated under the shear mode with a frequency of 1.9GHz. According to the apparent step-ladder curves of the frequency response to the change of blood viscoelasticity, the coagulation time (prothrombin time) and the coagulation kinetics were measured with the sample consumption of only 1μl. The procoagulant activity of thromboplastin and the anticoagulant effect of heparin on the blood coagulation process were illustrated exemplarily. The measured prothrombin times showed a good linear correlation with R(2)=0.99969 and a consistency with the coefficient of variation less than 5% compared with the commercial coagulometer. The proposed film bulk acoustic sensor, which has the advantages of small size, light weight, low cost, simple operation and little sample consumption, is a promising device for miniaturized, online and automated analytical system for routine diagnostics of hemostatic status and personal health monitoring.

  14. Lightweight Filter Architecture for Energy Efficient Mobile Vehicle Localization Based on a Distributed Acoustic Sensor Network

    PubMed Central

    Kim, Keonwook

    2013-01-01

    The generic properties of an acoustic signal provide numerous benefits for localization by applying energy-based methods over a deployed wireless sensor network (WSN). However, the signal generated by a stationary target utilizes a significant amount of bandwidth and power in the system without providing further position information. For vehicle localization, this paper proposes a novel proximity velocity vector estimator (PVVE) node architecture in order to capture the energy from a moving vehicle and reject the signal from motionless automobiles around the WSN node. A cascade structure between analog envelope detector and digital exponential smoothing filter presents the velocity vector-sensitive output with low analog circuit and digital computation complexity. The optimal parameters in the exponential smoothing filter are obtained by analytical and mathematical methods for maximum variation over the vehicle speed. For stationary targets, the derived simulation based on the acoustic field parameters demonstrates that the system significantly reduces the communication requirements with low complexity and can be expected to extend the operation time considerably. PMID:23979482

  15. Sound-maps of environmentally sensitive areas constructed from Wireless Acoustic Sensors Network data

    NASA Astrophysics Data System (ADS)

    Michailidis, E. T.; Liaperdos, J.; Tatlas, N.-A.; Potirakis, S. M.; Rangoussi, M.

    2016-03-01

    “E-SOUNDMAPS” is a distributed microelectronic system for the sound/acoustic monitoring of areas of environmental interest that is based on an appropriately designed wireless acoustic sensor network (WASN). It involves the automated generation of multi-level sound-maps for environmental assessment of areas of interest. This paper focuses on the method and the software application for the construction of sound-maps, which is developed as part of the integrated “E-SOUNDMAPS” system. The software application periodically produces geographically-referenced, accurate environmental sound information, based on real- field measurement data, and integrates them in the geographic map of the area of interest in a concise and comprehensive manner. Following the field recording of sound and the hierarchical recognition/classification of sound events and corresponding sources, the obtained sound sources characterization tags feed the specific software application. The output is a multilevel soundmap, constructed on the basis of the data and published electronically on the Web, for human inspection and assessment. All necessary steps for handling, archiving, monitoring, visualization and retrieval of sound data are also presented.

  16. Acoustic Emission and Velocity Measurements using a Modular Borehole Prototype Tool to Provide Real Time Rock Mass Characterization.

    NASA Astrophysics Data System (ADS)

    Collins, D. S.; Pettitt, W. S.; Young, R. P.

    2003-04-01

    Permanent changes to rock mass properties can occur due to the application of excavation or thermal induced stresses. This project involves the design of hardware and software for the long term monitoring of a rock volume, and the real time analysis and interpretation of induced microcracks and their properties. A set of borehole sondes have been designed with each sonde containing up to 6 sensor modules. Each piezoelectric sensor is dual mode allowing it to either transmit an ultrasonic pulse through a rock mass, or receive ultrasonic waveform data. Good coupling of the sensors with the borehole wall is achieved through a motorized clamping mechanism. The borehole sondes are connected to a surface interface box and digital acquisition system and controlled by a laptop computer. The system allows acoustic emission (AE) data to be recorded at all times using programmable trigger logic. The AE data is processed in real time for 3D source location and magnitude, with further analysis such as mechanism type available offline. Additionally the system allows velocity surveys to be automatically performed at pre-defined times. A modelling component of the project, using a 3D dynamic finite difference code, is investigating the effect that different microcrack distributions have on velocity waveform data in terms of time and frequency amplitude. The modelling codes will be validated using data recorded from laboratory tests on rocks with known crack fabrics, and then used in insitu experimental tests. This modelling information will be used to help interpret, in real time, microcrack characteristics such as crack density, size, and fluid content. The technology has applications in a number of branches of geotechnical and civil engineering including radioactive waste storage, mining, dams, bridges, and oil reservoir monitoring.

  17. Mass variation of a thin liquid film driven by an acoustic wave

    SciTech Connect

    Batson, W.; Agnon, Y.; Oron, A.

    2015-06-15

    In this work, we investigate the dynamics of a thin liquid film subjected to an acoustic field in its bounding vapor space. For large acoustic wavelengths, the field imposes a spatially uniform, temporally periodic temperature and pressure at the vapor side of the film interface, which leads to a periodic driving force for mass exchange with the vapor. Neglecting the dynamics of the vapor space, we adopt the “one-sided” model for evaporation/condensation of thin liquid films. In the interest of determining the effect of oscillatory mass exchange on film stability, we consider films in thermodynamic equilibrium with the mean vapor conditions. The effects of oscillatory phase change on both linear stability and nonlinear dynamics are investigated for slightly inclined ceiling films that are destabilized by gravity and subject to thermocapillary effects. At linear order, this mass exchange is not found to alter the band of unstable wave numbers and only marginally affects the growth rates. Additionally, the mass exchanged during evaporation is balanced by condensation so that the total mass of the liquid film is conserved. However, due to nonlinear effects, we find that traveling waves encouraged by the inclination are subject to net mass loss. It is then found that normal thermocapillary effects enhance this loss, and that anomalous thermocapillarity mitigates or even reverses the loss to a mass gain.

  18. Mass variation of a thin liquid film driven by an acoustic wave

    NASA Astrophysics Data System (ADS)

    Batson, W.; Agnon, Y.; Oron, A.

    2015-06-01

    In this work, we investigate the dynamics of a thin liquid film subjected to an acoustic field in its bounding vapor space. For large acoustic wavelengths, the field imposes a spatially uniform, temporally periodic temperature and pressure at the vapor side of the film interface, which leads to a periodic driving force for mass exchange with the vapor. Neglecting the dynamics of the vapor space, we adopt the "one-sided" model for evaporation/condensation of thin liquid films. In the interest of determining the effect of oscillatory mass exchange on film stability, we consider films in thermodynamic equilibrium with the mean vapor conditions. The effects of oscillatory phase change on both linear stability and nonlinear dynamics are investigated for slightly inclined ceiling films that are destabilized by gravity and subject to thermocapillary effects. At linear order, this mass exchange is not found to alter the band of unstable wave numbers and only marginally affects the growth rates. Additionally, the mass exchanged during evaporation is balanced by condensation so that the total mass of the liquid film is conserved. However, due to nonlinear effects, we find that traveling waves encouraged by the inclination are subject to net mass loss. It is then found that normal thermocapillary effects enhance this loss, and that anomalous thermocapillarity mitigates or even reverses the loss to a mass gain.

  19. Calibration of AN Acoustic Sensor (geophone) for Continuous Bedload Monitoring in Mountainous Streams

    NASA Astrophysics Data System (ADS)

    Tsakiris, A. G.; Papanicolaou, T.

    2010-12-01

    Measurement of bedload rates is a crucial component in the study of alluvial processes in mountainous streams. Stream restoration efforts, the validation of morphodynamic models and the calibration empirical transport formulae rely on accurate bedload transport measurements. Bedload measurements using traditional methods (e.g. samplers, traps) are time consuming, resource intensive and not always feasible, especially at higher flow conditions. These limitations could potentially be addressed by acoustic instruments, which may provide unattended, continuous bedload measurements even at higher flow conditions, provided that these instruments are properly calibrated. The objective of this study is to calibrate an acoustic instrument (geophone) for performing bedload measurements in a well-monitored laboratory environment at conditions corresponding to low flow regime in mountainous streams. The geophone was manufactured by ClampOn® and was attached to the bottom of a steel plate with dimensions 0.15x0.15 m. The geophone registers the energy of the acoustic signal produced by the movement of the bedload particles over the steel plate with time resolution of one second. The plate-sensor system was installed in an acrylic housing such that the steel plate top surface was at the same level with the surface of a flat porous bed consisting of unisize spheres with diameter 19.1 mm. Unisize spherical glass particles, 15.9 mm in diameter, were preplaced along a 2 m long section upstream of the sensor, and were entrained over the steel plate. In these experiments, the geophone records spanned the complete experiment duratio. Plan view video of the particle movement over the steel plate was recorded via an overhead camera, and was used to calculate the actual bedload rate over the steel plate. Synchronized analysis of this plan view video and the geophone time series revealed that the geophone detected 62% of the bedload particles passing over the steel plate, which triggered

  20. Acoustic sensor versus electrocardiographically derived respiratory rate in unstable trauma patients.

    PubMed

    Yang, Shiming; Menne, Ashley; Hu, Peter; Stansbury, Lynn; Gao, Cheng; Dorsey, Nicolas; Chiu, William; Shackelford, Stacy; Mackenzie, Colin

    2016-06-07

    Respiratory rate (RR) is important in many patient care settings; however, direct observation of RR is cumbersome and often inaccurate, and electrocardiogram-derived RR (RRECG) is unreliable. We asked how data derived from the first 15 min of RR recording after trauma center admission using a novel acoustic sensor (RRa) would compare to RRECG and to end-tidal carbon dioxide-based RR ([Formula: see text]) from intubated patients, the "gold standard" in predicting life-saving interventions in unstable trauma patients. In a convenience sample subset of trauma patients admitted to our Level 1 trauma center, enrolled in the ONPOINT study, and monitored with RRECG, some of whom also had [Formula: see text] data, we collected RRa using an adhesive sensor with an integrated acoustic transducer (Masimo RRa™). Using Bland-Altman analysis of area under the receiver operating characteristic (AUROC) curves, we compared the first 15 min of continuous RRa and RRECG to [Formula: see text] and assessed the performance of these three parameters compared to the Revised Trauma Score (RTS) in predicting blood transfusion 3, 6, and 12 h after admission. Of the 1200 patients enrolled in ONPOINT from December 2011 to May 2013, 1191 had RRECG data recorded in the first 15 min, 358 had acoustic monitoring, and 14 of the latter also had [Formula: see text]. The three groups did not differ demographically or in mechanism of injury. RRa showed less bias (0.8 vs. 6.9) and better agreement than RRECG when compared to [Formula: see text]. At [Formula: see text] 10-29 breaths per minute, RRa was more likely to be the same as [Formula: see text] and assign the same RTS. In predicting transfusion, features derived from RRa and RRECG gave AUROCs 0.59-0.66 but with true positive rate 0.70-0.89. RRa monitoring is a non-invasive option to glean valid RR data to assist clinical decision making and could contribute to prediction models in non-intubated unstable trauma patients.

  1. Thickness mode EMIS of constrained proof-mass piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Kamas, Tuncay; Giurgiutiu, Victor; Lin, Bin

    2015-11-01

    This paper addresses theoretical and experimental work on thickness-mode electromechanical (E/M) impedance spectroscopy (EMIS) of proof-mass piezoelectric wafer active sensors (PMPWAS). The proof-mass (PM) concept was used to develop a new method for tuning the ultrasonic wave modes and for relatively high frequency local modal sensing by the PM affixed on PWAS. In order to develop the theoretical basis of the PMPWAS tuning concept, analytical analyses were conducted by applying the resonator theory to derive the EMIS of a PWAS constrained on one and both surfaces by isotropic elastic materials. The normalized thickness-mode shapes were obtained for the normal mode expansion (NME) method to eventually predict the thickness-mode EMIS using the correlation between PMPWAS and the structural dynamic properties of the substrate. Proof-masses of different sizes and materials were used to tune the system resonance towards an optimal frequency point. The results were verified by coupled-field finite element analyses (CF-FEA) and experimental results. An application of the tuning effect of PM on the standing wave modes was discussed as the increase in PM thickness shifts the excitation frequency of the wave mode toward the surface acoustic wave (SAW) mode.

  2. [Comparision of forced expiratory time, recorded by two spirometers with flow sensors of various types, and acoustic duration of tracheal forced expiratory noises].

    PubMed

    Malaeva, V V; Pochekutova, I A; Korenbaum, V I

    2015-01-01

    In the sample of 44 volunteers forced expiratory time values obtained in spirometers, equipped with flow sensor of Lilly type and turbine flow sensor, and acoustic duration of tracheal forced expiratory noises are compared. It is shown that spirometric forced expiratory time is dependent on flow sensor type. Therefore it can't be used in diagnostic aims.

  3. Analyzing the applicability of miniature ultra-high sensitivity Fabry-Perot acoustic sensor using a nanothick graphene diaphragm

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Gao, Xiangyang; Guo, Tingting; Xiao, Jun; Fan, Shangchun; Jin, Wei

    2015-08-01

    A miniature Fabry-Perot interferometric acoustic sensor with an ultra-high pressure sensitivity was constructed by using approximately 13 layers of graphene film as the diaphragm. The extremely thin diaphragm was transferred onto the endface of a ferrule, which had an inner diameter of 125 μm, and van der Waals interactions between the graphene diaphragm and its substrate created a low finesse Fabry-Perot interferometer with a cavity length of 98 μm. Acoustic testing demonstrated a pressure-induced deflection of 2380 nm kPa-1 and a noise equivalent acoustic signal level of ~2.7 mPa/Hz1/2 for a 3 dB bandwidth with a center frequency of 15 kHz. The sensor also exhibited a dynamic frequency response between 1 and 20 kHz, which conformed well to the result obtained by a reference microphone. The use of a suspended graphene diaphragm has potential applications in highly sensitive pressure/acoustic sensors.

  4. Mass and position determination in MEMS mass sensors: a theoretical and an experimental investigation

    NASA Astrophysics Data System (ADS)

    Bouchaala, Adam; Nayfeh, Ali H.; Jaber, Nizar; Younis, Mohammad I.

    2016-10-01

    We present a method to determine accurately the position and mass of an entity attached to the surface of an electrostatically actuated clamped-clamped microbeam implemented as a mass sensor. In the theoretical investigation, the microbeam is modeled as a nonlinear Euler-Bernoulli beam and a perturbation technique is used to develop a closed-form expression for the frequency shift due to an added mass at a specific location on the microbeam surface. The experimental investigation was conducted on a microbeam made of Polyimide with a special lower electrode to excite both of the first and second modes of vibration. Using an ink-jet printer, we deposited droplets of polymers with a defined mass and position on the surface of the microbeam and we measured the shifts in its resonance frequencies. The theoretical predictions of the mass and position of the deposited droplets match well with the experimental measurements.

  5. Energy Balanced Strategies for Maximizing the Lifetime of Sparsely Deployed Underwater Acoustic Sensor Networks

    PubMed Central

    Luo, Hanjiang; Guo, Zhongwen; Wu, Kaishun; Hong, Feng; Feng, Yuan

    2009-01-01

    Underwater acoustic sensor networks (UWA-SNs) are envisioned to perform monitoring tasks over the large portion of the world covered by oceans. Due to economics and the large area of the ocean, UWA-SNs are mainly sparsely deployed networks nowadays. The limited battery resources is a big challenge for the deployment of such long-term sensor networks. Unbalanced battery energy consumption will lead to early energy depletion of nodes, which partitions the whole networks and impairs the integrity of the monitoring datasets or even results in the collapse of the entire networks. On the contrary, balanced energy dissipation of nodes can prolong the lifetime of such networks. In this paper, we focus on the energy balance dissipation problem of two types of sparsely deployed UWA-SNs: underwater moored monitoring systems and sparsely deployed two-dimensional UWA-SNs. We first analyze the reasons of unbalanced energy consumption in such networks, then we propose two energy balanced strategies to maximize the lifetime of networks both in shallow and deep water. Finally, we evaluate our methods by simulations and the results show that the two strategies can achieve balanced energy consumption per node while at the same time prolong the networks lifetime. PMID:22399970

  6. Throughput and energy efficiency of a cooperative hybrid ARQ protocol for underwater acoustic sensor networks.

    PubMed

    Ghosh, Arindam; Lee, Jae-Won; Cho, Ho-Shin

    2013-11-08

    Due to its efficiency, reliability and better channel and resource utilization, cooperative transmission technologies have been attractive options in underwater as well as terrestrial sensor networks. Their performance can be further improved if merged with forward error correction (FEC) techniques. In this paper, we propose and analyze a retransmission protocol named Cooperative-Hybrid Automatic Repeat reQuest (C-HARQ) for underwater acoustic sensor networks, which exploits both the reliability of cooperative ARQ (CARQ) and the efficiency of incremental redundancy-hybrid ARQ (IR-HARQ) using rate-compatible punctured convolution (RCPC) codes. Extensive Monte Carlo simulations are performed to investigate the performance of the protocol, in terms of both throughput and energy efficiency. The results clearly reveal the enhancement in performance achieved by the C-HARQ protocol, which outperforms both CARQ and conventional stop and wait ARQ (S&W ARQ). Further, using computer simulations, optimum values of various network parameters are estimated so as to extract the best performance out of the C-HARQ protocol.

  7. Influence of the vibro-acoustic sensor position on cavitation detection in a Kaplan turbine

    NASA Astrophysics Data System (ADS)

    Schmidt, H.; Kirschner, O.; Riedelbauch, S.; Necker, J.; Kopf, E.; Rieg, M.; Arantes, G.; Wessiak, M.; Mayrhuber, J.

    2014-03-01

    Hydraulic turbines can be operated close to the limits of the operating range to meet the demand of the grid. When operated close to the limits, the risk increases that cavitation phenomena may occur at the runner and / or at the guide vanes of the turbine. Cavitation in a hydraulic turbine can cause material erosion on the runner and other turbine parts and reduce the durability of the machine leading to required outage time and related repair costs. Therefore it is important to get reliable information about the appearance of cavitation during prototype operation. In this experimental investigation the high frequency acoustic emissions and vibrations were measured at 20 operating points with different cavitation behaviour at different positions in a large prototype Kaplan turbine. The main goal was a comparison of the measured signals at different sensor positions to identify the sensitivity of the location for cavitation detection. The measured signals were analysed statistically and specific values were derived. Based on the measured signals, it is possible to confirm the cavitation limit of the examined turbine. The result of the investigation shows that the position of the sensors has a significant influence on the detection of cavitation.

  8. A surface acoustic wave sensor functionalized with a polypyrrole molecularly imprinted polymer for selective dopamine detection.

    PubMed

    Maouche, Naima; Ktari, Nadia; Bakas, Idriss; Fourati, Najla; Zerrouki, Chouki; Seydou, Mahamadou; Maurel, François; Chehimi, Mohammed Mehdi

    2015-11-01

    A surface acoustic wave sensor operating at 104 MHz and functionalized with a polypyrrole molecularly imprinted polymer has been designed for selective detection of dopamine (DA). Optimization of pyrrole/DA ratio, polymerization and immersion times permitted to obtain a highly selective sensor, which has a sensitivity of 0.55°/mM (≈ 550 Hz/mM) and a detection limit of ≈ 10 nM. Morphology and related roughness parameters of molecularly imprinted polymer surfaces, before and after extraction of DA, as well as that of the non imprinted polymer were characterized by atomic force microscopy. The developed chemosensor selectively recognized dopamine over the structurally similar compound 4-hydroxyphenethylamine (referred as tyramine), or ascorbic acid,which co-exists with DA in body fluids at a much higher concentration. Selectivity tests were also carried out with dihydroxybenzene, for which an unexpected phase variation of order of 75% of the DA one was observed. Quantum chemical calculations, based on the density functional theory, were carried out to determine the nature of interactions between each analyte and the PPy matrix and the DA imprinted PPy polypyrrole sensing layer in order to account for the important phase variation observed during dihydroxybenzene injection.

  9. Acoustic metamaterial bar with non-linear spring-mass cells

    NASA Astrophysics Data System (ADS)

    Lin, Guochang; He, Ge; Sun, Hongwei

    2016-04-01

    In this paper we present experimental and theoretical results on an acoustic metamaterial bar that exhibits negative effective mass and negative effective stiffness. A one-dimensional acoustic metamaterial bar with an group of non-linear spring-mass cells in was fabricated. The frequency characteristics of the acoustic metamaterial have the same form as that of the permittivity in metals due to the plasma oscillation. We also provide a theory to explain the simulation results. And numerical simulations reveal that the actual working mechanism of the proposed metamaterial bar is based on the concept of conventional mechanical vibration absorbers. It uses the incoming elastic wave in the bar to resonate the integrated spring-mass-damper absorbers to vibrate in their optical mode at frequencies close to but above their local resonance frequencies to create shear forces and bending moments to straighten the bar and stop the wave propagation. Moreover, we design a finite periodic system composed of such basic units to confirm that the modeling and analysis techniques are available.

  10. Resonating cantilever mass sensor with mechanical on-plane excitation

    NASA Astrophysics Data System (ADS)

    Teva, Jordi; Abadal, Gabriel; Jordà, Xavier; Borrise, Xavier; Davis, Zachary; Barniol, Nuria

    2003-04-01

    The aim of this paper is to report the experimental setup designed, developed and tested in order to achieve the first vibrating mode of a lateral cantilever with mechanical excitation. The on-plane oscillating cantilever is the basis of a proposed mass sensor with an expected resolution in the atto-gram scale. In a first system design, the cantilever is driven electrostatically by an electrode, which is placed parallel to the cantilever. The cantilever is driven to its first resonant mode applying an AC voltage between the cantilever and a driver. Also, a DC voltage is applied to increase the system response. The signal read-out of the transducer is the capacitive current of the cantilever-driver system. The mass sensor proposed, based on this cantilever-driver structure (CDS), is integrated with a CMOS circuitry in order to minimize the parasitic capacitances, that in this case take special relevance because of the low level output current coming from the transducer. Moreover, the electrostatic excitation introduces a parasitic current that overlaps the current due to the resonance. The mechanical excitation is an alternative excitation method which aim is to eliminate the excitation current. Here we describe the experimental facilities developed to achieve mechanical excitation and report preliminary results obtained by this excitation technique. The results are complemented with dynamic simulations of an equivalent system model that are in accordance with the experimental values.

  11. A film bulk acoustic resonator-based high-performance pressure sensor integrated with temperature control system

    NASA Astrophysics Data System (ADS)

    Zhang, Mengying; Zhao, Zhan; Du, Lidong; Fang, Zhen

    2017-04-01

    This paper presented a high-performance pressure sensor based on a film bulk acoustic resonator (FBAR). The support film of the FBAR chip was made of silicon nitride and the part under the resonator area was etched to enhance the sensitivity and improve the linearity of the pressure sensor. A micro resistor temperature sensor and a micro resistor heater were integrated in the chip to monitor and control the operating temperature. The sensor chip was fabricated, and packaged in an oscillator circuit for differential pressure detection. When the detected pressure ranged from  ‑100 hPa to 600 hPa, the sensitivity of the improved FBAR pressure sensor was  ‑0.967 kHz hPa‑1, namely  ‑0.69 ppm hPa‑1, which was 19% higher than that of existing sensors with a complete support film. The nonlinearity of the improved sensor was less than  ±0.35%, while that of the existing sensor was  ±5%. To eliminate measurement errors from humidity, the temperature control system integrated in the sensor chip controlled the temperature of the resonator up to 75 °C, with accuracy of  ±0.015 °C and power of 20 mW.

  12. A lateral field excited ZnO film bulk acoustic wave sensor working in viscous environments

    NASA Astrophysics Data System (ADS)

    Chen, Da; Wang, Jingjing; Xu, Yan; Li, Dehua; Zhang, Liuyin; Liu, Weihui

    2013-09-01

    We present a lateral field excited ZnO film bulk acoustic resonator (FBAR) operated in pure-shear mode and analyze its performances in viscous liquids. The electrodes of the device are located on the film surface and normal to the c-axis of the ZnO film. The proposed device works near 1.44 GHz with a Q-factor up to 360 in air and 310 in water, which are higher than those of the quasi-shear thickness field excited FBAR. The resonant frequency is decreased with the increasing square root of the product of the viscosity and density with a linear dependence in the viscosity below 148.7 mPa s. The mass sensitivity of 670 Hz cm2 ng-1 was measured by monitoring the frequency change during the volatilization of saline solution loaded on the resonator. In addition, the levels of the noise and the mass resolutions were measured in various viscous environments. The proposed device yields the mass resolution of 670 Hz cm2 ng-1 and the high mass resolution of 0.06 ng cm-2. These results indicated that the lateral field excited ZnO FBAR had superior sensitivity for the bio-sensing applications in viscous biological liquids.

  13. Effects of an elastic mass on frequency response characteristics of an ultra-thin piezoelectric micro-acoustic actuator.

    PubMed

    Kim, Hye Jin; Yang, Woo Seok; No, Kwangsoo

    2013-08-01

    This paper presents an optimized method to improve the sound quality of ultra-thin piezoelectric micro-acoustic actuators. To achieve flat and smooth frequency response characteristics of the piezoelectric acoustic actuators, we have proposed an elastic mass attached to the acoustic diaphragm. The effects of the elastic mass on frequency response characteristics of the piezoelectric acoustic actuator were investigated by finite element analysis simulation and laser scanning vibrometer measurement. Based on the modal and vibrational characteristics, it was found that the fabricated piezoelectric acoustic actuator has a significant dip of 1.32 kHz and peak of 2.24 kHz, which correspond respectively to the (1,3) and (3,1) resonant modes of the acoustic diaphragm. However, by attaching an elastic mass to the acoustic diaphragm with a shape similar to the (3,1) mode, the resonant frequencies corresponding to the (1,3) and (3,1) modes shifted to higher frequencies and the vibrational displacements at each mode were dramatically reduced by about 40%. As a result, the dip at (1,3) mode was greatly improved by 13 dB and total harmonic distortion was dramatically reduced from 80.83% to 8.71%. This paper shows that the optimized elastic mass can allow flat and smooth frequency response characteristics by improving the significant peak and dip.

  14. Network of acoustic sensors for the detection of weapons firing: tests for the choice of individual sensing elements

    NASA Astrophysics Data System (ADS)

    Naz, P.; Marty, Ch.; Hengy, S.; Hamery, P.

    2010-04-01

    The detection and localization of weapon firing on the battlefield is envisaged by means of acoustic waves. The main objective of this work is to compare various sensing elements that can be integrated in acoustic arrays. Experimental measurements of sound waves obtained by using some of these elements in Unattended Ground Sensors are presented for snipers, mortars or artillery guns. The emphasis will be put on the characteristics of the sensing elements needed to detect and classify the Mach wave generated by a supersonic projectile and the muzzle wave generated by the combustion of the propulsion powder. Examples of preliminary prototypes are presented to illustrate our topic. We will concentrate on a wearable system considered to improve the soldier's awareness of the surrounding threats: this realization consists of a network of three helmets integrating an acoustic array for the detection and localization of snipers.

  15. Observation of acoustic streaming in water/sensor plate/thin water layer/128YX-LiNbO3 for realizing disposable digital microfluidic system

    NASA Astrophysics Data System (ADS)

    Kondoh, Jun; Toyoizumi, Hitoshi

    2012-09-01

    One application of a surface acoustic wave (SAW) device is a droplet manipulator. If a sensor is fabricated on the manipulation surface, digital microfluidic system (DMFS) is realized. For disposable application, structure of sensor plate/liquid layer/ 128YX-LiNbO3 is proposed. In this paper, acoustic streaming on a DMFS is experimentally observed. As the streaming in a droplet depends on a contact angle, it in the tank was observed. The radiation patterns on the 128YX-LiNbO3 and sensor plate are differences. The results indicate that the radiation on the sensor plate depends on plate material and thickness.

  16. A surface acoustic wave humidity sensor with high sensitivity based on electrospun MWCNT/Nafion nanofiber films

    NASA Astrophysics Data System (ADS)

    Sheng, Lei; Dajing, Chen; Yuquan, Chen

    2011-07-01

    Humidity detection has been widely used in a variety of fields. A humidity sensor with high sensitivity is reported in this paper. A surface acoustic wave resonator (SAWR) with high resonance frequency was fabricated as a basic sensitive component. Various nanotechnologies were used to improve the sensor's performance. A multi-walled carbon nanotube/Nafion (MWCNT/Nafion) composite material was prepared as humidity-sensitive films, deposited on the surface of an SAWR by the electrospinning method. The electrospun MWCNT/Nafion nanofiber films showed a three-dimensional (3D) porous structure, which was profitable for improving the sensor's performance. The new nano-water-channel model of Nafion was also applied in the humidity sensing process. Compared to other research, the present sensor showed excellent sensitivity (above 400 kHz/% relative humidity (RH) in the range from 10% RH to 80% RH), good linearity (R2 > 0.98) and a short response time (~3 s@63%).

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

    PubMed

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

    2015-06-01

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

  18. Self-adapting root-MUSIC algorithm and its real-valued formulation for acoustic vector sensor array

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Zhang, Guo-jun; Xue, Chen-yang; Zhang, Wen-dong; Xiong, Ji-jun

    2012-12-01

    In this paper, based on the root-MUSIC algorithm for acoustic pressure sensor array, a new self-adapting root-MUSIC algorithm for acoustic vector sensor array is proposed by self-adaptive selecting the lead orientation vector, and its real-valued formulation by Forward-Backward(FB) smoothing and real-valued inverse covariance matrix is also proposed, which can reduce the computational complexity and distinguish the coherent signals. The simulation experiment results show the better performance of two new algorithm with low Signal-to-Noise (SNR) in direction of arrival (DOA) estimation than traditional MUSIC algorithm, and the experiment results using MEMS vector hydrophone array in lake trails show the engineering practicability of two new algorithms.

  19. Acoustic emission source localization in thin metallic plates: A single-sensor approach based on multimodal edge reflections.

    PubMed

    Ebrahimkhanlou, A; Salamone, S

    2017-03-14

    This paper presents a new acoustic emission (AE) source localization for isotropic plates with reflecting boundaries. This approach that has no blind spot leverages multimodal edge reflections to identify AE sources with only a single sensor. The implementation of the proposed approach involves three main steps. First, the continuous wavelet transform (CWT) and the dispersion curves of the fundamental Lamb wave modes are utilized to estimate the distance between an AE source and a sensor. This step uses a modal acoustic emission approach. Then, an analytical model is proposed that uses the estimated distances to simulate the edge-reflected waves. Finally, the correlation between the experimental and the simulated waveforms is used to estimate the location of AE sources. Hsu-Nielsen pencil lead break (PLB) tests were performed on an aluminum plate to validate this algorithm and promising results were achieved. Based on these results, the paper reports the statistics of the localization errors.

  20. Layered surface acoustic wave devices for film characterization and sensor applications

    NASA Astrophysics Data System (ADS)

    Pedrick, Michael K.

    2007-05-01

    This work has introduced novel applications for Layered Surface Acoustic Wave (SAW) devices along with concepts for enhanced sensitivity via refined modeling techniques. The derivation of Love Wave and Rayleigh wave propagation pertinent to SAW substrates with thin film overlayers was explored. Novel aspects were presented for Finite Element analysis of Layered SAW sensors. This included coordinate transformations of model geometries to coincide with crystallographic orientations known to generate Surface Skimming Bulk Waves (SSBW) and various Rayleigh wave types of propagation in ST Quartz, 90° rotated ST Quartz, and 77° Y rotated Lithium Tantalate. This work has shown for the first time, FEM prediction of SSBW, Generalized SAW and High Velocity SAW waves. Rayleigh damping properties were extended to develop a Finite element model capable of predicting Layered SAW response to glass transition in a polymer film. The ability to monitor localized mechanical behavior in a PMMA film was explored with Love Waves generated by 90° rotated ST Quartz and Shear Vertical (SV)-SAWs generated by 77° Y rotated Lithium Tantalate. Similar trends were found experimentally as compared to the Finite element models. The capability of Love Wave devices for monitoring polymer film curing behavior was investigated. The ability to qualitatively assess the bond quality between film and substrate was also demonstrated based on the characteristics of the transmitted frequency response. The results of these developments have laid the ground work for developing diagnostic tools to better characterize film behavior in practical applications. Several sensor applications for Layered SAW devices were discussed. The Shear Horizontal displacement of the Love Wave device was exploited to demonstrate the capability of such a sensor for ice detection. A clear distinction between air, water, and ice loading was found with Love Waves whereas SV-SAWs were unable to distinguish between liquid and ice

  1. Development of a surface acoustic wave gas sensor for organophosphorus nerve agents employing lanthanide compounds as the chemical interface.

    PubMed

    Nieuwenhuizen, M S; Harteveld, J L

    1994-03-01

    The results of a study dealing with surface acoustic wave gas sensors for organophosphorus compounds such as nerve agents are described. Several lanthanum coordination compounds were applied as the chemical interface. The various sensors prepared were challenged with both the nerve agent sarin and the simulant dimethyl methylphosphonate. Many aspects were studied, such as sensitivity, selectivity, reversibility and response rate as well as the effect of temperature and structural features. Detection limits down to 0.1 ppm were found. Response rates require further improvement. Degradation phenomena were observed which in some cases yielded irreversible responses. The selectivity for organophosphorus compounds was found to be promising.

  2. Suspended particulate matter estimates using optical and acoustic sensors: application in Nestos River plume (Thracian Sea, North Aegean Sea).

    PubMed

    Anastasiou, Sotiria; Sylaios, Georgios K; Tsihrintzis, Vassilios A

    2015-06-01

    The present study investigates the use of combined methods of optical and acoustic sensors, in collaboration with direct in situ measurements, for the calibration and validation of a model transforming acoustic backscatter intensity series into suspended particulate matter (SPM) concentration datasets. The model follows previously elaborated techniques, placing particular attention to the parameterization of the acoustic absorption index as a function of water physical properties. Results were obtained from the annual deployment (during 2007-2008) of an upward-facing acoustic Doppler current profiler (ADCP) (307 kHz), equipped with a Wave Array, and an optical backscatter sensor (OBS), at the bottom of Thassos Passage near Nestos River plume (Thracian Sea, Northern Greece). The OBS was calibrated through linear regression, using 2007 and 2012 field sampling data, exhibiting an error of 13-14 % due to chlorophyll presence. The ADCP signal was calibrated through simultaneous measurements of backscatter intensity and turbidity profiles. Harmonic analysis on the model-produced SPM concentrations explained the tidal influence on their variability, especially during the summer. Empirical orthogonal functions analysis revealed the impact of waves and wave-induced currents on SPM variability. Finally, Nestos River sediment load was found uncorrelated to the SPM change in Thassos Passage, due to the dispersal and sediment deposition near the river mouth.

  3. Biomass of zooplankton estimated by acoustical sensors in the Arabian sea. Final report

    SciTech Connect

    Holliday, D.V.

    1996-11-22

    The long term goal of our overall research program is the development of data-based models to predict ecological relationships of zooplankton, phytoplankton and the physical environment in the sea. The overall objective of the work carried out within the scope of this particular contract was to acoustically measure the dynamics of zooplankton and micronekton in the northern Arabian Sea during several seasons. The scientific focus was to examine the impact, if any, of the two annual monsoons that are thought to drive the ecosystem response in the area. This particular project involved the design and construction of two sensors which were then deployed in the Arabian Sea by several of our co-PIVs in the ONR ARI on Forced Upper Ocean Dynamics during the time period in which the JGOFS program also focused their efforts on the northern Arabian Sea. This contract involved only the development, calibration and maintenance of the instrumentation. The data processing, other than that which has been necessary for the purposes of quality assurance, was not induded in our original proposal.

  4. A novel acoustic sensor approach to classify seeds based on sound absorption spectra.

    PubMed

    Gasso-Tortajada, Vicent; Ward, Alastair J; Mansur, Hasib; Brøchner, Torben; Sørensen, Claus G; Green, Ole

    2010-01-01

    A non-destructive and novel in situ acoustic sensor approach based on the sound absorption spectra was developed for identifying and classifying different seed types. The absorption coefficient spectra were determined by using the impedance tube measurement method. Subsequently, a multivariate statistical analysis, i.e., principal component analysis (PCA), was performed as a way to generate a classification of the seeds based on the soft independent modelling of class analogy (SIMCA) method. The results show that the sound absorption coefficient spectra of different seed types present characteristic patterns which are highly dependent on seed size and shape. In general, seed particle size and sphericity were inversely related with the absorption coefficient. PCA presented reliable grouping capabilities within the diverse seed types, since the 95% of the total spectral variance was described by the first two principal components. Furthermore, the SIMCA classification model based on the absorption spectra achieved optimal results as 100% of the evaluation samples were correctly classified. This study contains the initial structuring of an innovative method that will present new possibilities in agriculture and industry for classifying and determining physical properties of seeds and other materials.

  5. A Synthetic Phased Array Surface Acoustic Wave Sensor for Quantifying Bolt Tension

    PubMed Central

    Martinez, Jairo; Sisman, Alper; Onen, Onursal; Velasquez, Dean; Guldiken, Rasim

    2012-01-01

    In this paper, we report our findings on implementing a synthetic phased array surface acoustic wave sensor to quantify bolt tension. Maintaining proper bolt tension is important in many fields such as for ensuring safe operation of civil infrastructures. Significant advantages of this relatively simple methodology is its capability to assess bolt tension without any contact with the bolt, thus enabling measurement at inaccessible locations, multiple bolt measurement capability at a time, not requiring data collection during the installation and no calibration requirements. We performed detailed experiments on a custom-built flexible bench-top experimental setup consisting of 1018 steel plate of 12.7 mm (½ in) thickness, a 6.4 mm (¼ in) grade 8 bolt and a stainless steel washer with 19 mm (¾ in) of external diameter. Our results indicate that this method is not only capable of clearly distinguishing properly bolted joints from loosened joints but also capable of quantifying how loose the bolt actually is. We also conducted detailed signal-to-noise (SNR) analysis and showed that the SNR value for the entire bolt tension range was sufficient for image reconstruction.

  6. Evaluation of MPEG-7-Based Audio Descriptors for Animal Voice Recognition over Wireless Acoustic Sensor Networks.

    PubMed

    Luque, Joaquín; Larios, Diego F; Personal, Enrique; Barbancho, Julio; León, Carlos

    2016-05-18

    Environmental audio monitoring is a huge area of interest for biologists all over the world. This is why some audio monitoring system have been proposed in the literature, which can be classified into two different approaches: acquirement and compression of all audio patterns in order to send them as raw data to a main server; or specific recognition systems based on audio patterns. The first approach presents the drawback of a high amount of information to be stored in a main server. Moreover, this information requires a considerable amount of effort to be analyzed. The second approach has the drawback of its lack of scalability when new patterns need to be detected. To overcome these limitations, this paper proposes an environmental Wireless Acoustic Sensor Network architecture focused on use of generic descriptors based on an MPEG-7 standard. These descriptors demonstrate it to be suitable to be used in the recognition of different patterns, allowing a high scalability. The proposed parameters have been tested to recognize different behaviors of two anuran species that live in Spanish natural parks; the Epidalea calamita and the Alytes obstetricans toads, demonstrating to have a high classification performance.

  7. Health sensor for human body by using infrared, acoustic energy and magnetic signature

    NASA Astrophysics Data System (ADS)

    Wu, Jerry

    2013-05-01

    There is a general chain of events that applies to infections. Human body infection could causes by many different types of bacteria and virus in different areas or organ systems. In general, doctor can't find out the right solution/treatment for infections unless some certain types of bacteria or virus are detected. These detecting processes, usually, take few days to one week to accomplish. However, some infections of the body may not be able to detect at first round and the patient may lose the timing to receive the proper treatment. In this works, we base on Chi's theory which is an invisible circulation system existed inside the body and propose a novel health sensor which summarizes human's infrared, acoustic energy and magnetic signature and find out, in minutes, the most possible area or organ system that cause the infection just like what Chi-Kung master can accomplish. Therefore, the detection process by doctor will be shortened and it raises the possibility to give the proper treatment to the patient in the earliest timing.

  8. Novel cable coupling technique for improved shallow distributed acoustic sensor VSPs

    NASA Astrophysics Data System (ADS)

    Munn, Jonathan D.; Coleman, Thomas I.; Parker, Beth L.; Mondanos, Michael J.; Chalari, Athena

    2017-03-01

    Vertical seismic profiles (VSPs) collected using fiber optic distributed acoustic sensors (DAS) are becoming increasingly common; yet, ensuring good cable coupling with the borehole wall remains a persistent challenge. Traditional cable deployment techniques used in the petroleum industry are either not possible or do not provide data of sufficient quality for shallow applications. Additionally, no direct field comparison of coupling techniques in the same borehole exists to determine the impacts of poor coupling on DAS VSP data quality. This paper addresses these issues by: (1) presenting a novel cable coupling solution using a removable and relatively inexpensive FLUTe™ flexible borehole liner; and (2) presenting field examples of DAS VSPs under different coupling conditions. The proposed coupling technique is analogous to a fully cemented deployment in that the cable is continuously coupled directly to the formation. Field experiments conducted to assess and validate the technique demonstrate a marked improvement in VSP data quality when the cable is coupled with a flexible borehole liner. Without the liner, seismic profiles are dominated by a high-amplitude cable wave and the p-wave arrival is not observed; however, with cable coupling provided by a borehole liner inflated using hydrostatic pressure, the cable wave is suppressed and clear p-wave arrivals are visible. Additional tests examining the influence of fiber optic cable structure on seismic responses demonstrate that tight buffered fibers are more sensitive to dynamic strain than loose tube fibers making them potentially better suited for certain DAS applications.

  9. Evaluating damage potential of cryogenic concrete using acoustic emission sensors and permeability testing

    NASA Astrophysics Data System (ADS)

    Kogbara, Reginald B.; Parsaei, Boback; Iyengar, Srinath R.; Grasley, Zachary C.; Masad, Eyad A.; Zollinger, Dan G.

    2014-04-01

    This study evaluates the damage potential of concrete of different mix designs subjected to cryogenic temperatures, using acoustic emission (AE) and permeability testing. The aim is to investigate design methodologies that might be employed to produce concrete that resists damage when cooled to cryogenic temperatures. Such concrete would be suitable for primary containment of liquefied natural gas (LNG) and could replace currently used 9% Ni steel, thereby leading to huge cost savings. In the experiments described, concrete cubes, 150 mm x 150 mm x 150 mm, were cast using four different mix designs. The four mixes employed siliceous river sand as fine aggregate. Moreover, limestone, sandstone, trap rock and lightweight aggregate were individually used as coarse aggregates in the mixes. The concrete samples were then cooled from room temperature (20°C) to cryogenic temperature (-165°C) in a temperature chamber. AE sensors were placed on the concrete cubes during the cryogenic freezing process. The damage potential was evaluated in terms of the growth of damage as determined from AE, as a function of temperature and concrete mixture design. The damage potential observed was validated with water permeability testing. Initial results demonstrate the effects of the coefficient of thermal expansion (CTE) of the aggregates on damage growth. Concrete damage (cracking) resistance generally decreased with increasing coarse aggregate CTE, and was in the order, limestone ≥ trap rock << lightweight aggregate ≥ sandstone. Work is in progress to fully understand thermal dilation and damage growth in concrete due to differential CTE of its components.

  10. Gearbox tooth cut fault diagnostics using acoustic emission and vibration sensors--a comparative study.

    PubMed

    Qu, Yongzhi; He, David; Yoon, Jae; Van Hecke, Brandon; Bechhoefer, Eric; Zhu, Junda

    2014-01-14

    In recent years, acoustic emission (AE) sensors and AE-based techniques have been developed and tested for gearbox fault diagnosis. In general, AE-based techniques require much higher sampling rates than vibration analysis-based techniques for gearbox fault diagnosis. Therefore, it is questionable whether an AE-based technique would give a better or at least the same performance as the vibration analysis-based techniques using the same sampling rate. To answer the question, this paper presents a comparative study for gearbox tooth damage level diagnostics using AE and vibration measurements, the first known attempt to compare the gearbox fault diagnostic performance of AE- and vibration analysis-based approaches using the same sampling rate. Partial tooth cut faults are seeded in a gearbox test rig and experimentally tested in a laboratory. Results have shown that the AE-based approach has the potential to differentiate gear tooth damage levels in comparison with the vibration-based approach. While vibration signals are easily affected by mechanical resonance, the AE signals show more stable performance.

  11. Gearbox Tooth Cut Fault Diagnostics Using Acoustic Emission and Vibration Sensors — A Comparative Study

    PubMed Central

    Qu, Yongzhi; He, David; Yoon, Jae; Van Hecke, Brandon; Bechhoefer, Eric; Zhu, Junda

    2014-01-01

    In recent years, acoustic emission (AE) sensors and AE-based techniques have been developed and tested for gearbox fault diagnosis. In general, AE-based techniques require much higher sampling rates than vibration analysis-based techniques for gearbox fault diagnosis. Therefore, it is questionable whether an AE-based technique would give a better or at least the same performance as the vibration analysis-based techniques using the same sampling rate. To answer the question, this paper presents a comparative study for gearbox tooth damage level diagnostics using AE and vibration measurements, the first known attempt to compare the gearbox fault diagnostic performance of AE- and vibration analysis-based approaches using the same sampling rate. Partial tooth cut faults are seeded in a gearbox test rig and experimentally tested in a laboratory. Results have shown that the AE-based approach has the potential to differentiate gear tooth damage levels in comparison with the vibration-based approach. While vibration signals are easily affected by mechanical resonance, the AE signals show more stable performance. PMID:24424467

  12. Multi-functional surface acoustic wave sensor for monitoring enviromental and structural condition

    NASA Astrophysics Data System (ADS)

    Furuya, Y.; Kon, T.; Okazaki, T.; Saigusa, Y.; Nomura, T.

    2006-03-01

    As a first step to develop a health monitoring system with active and embedded nondestructive evaluation devices for the machineries and structures, multi-functional SAW (surface acoustic wave) device was developed. A piezoelectric LiNbO3(x-y cut) materials were used as a SAW substrate on which IDT(20μm pitch) was produced by lithography. On the surface of a path of SAW between IDTs, environmentally active material films of shape memory Ti50Ni41Cu(at%) with non-linear hysteresis and superelastic Ti48Ni43Cu(at%) with linear deformation behavior were formed by magnetron-sputtering technique. In this study, these two kinds of shape memory alloys SMA) system were used to measure 1) loading level, 2) phase transformation and 3)stress-strain hysteresis under cyclic loading by utilizing their linearity and non-linearity deformation behaviors. Temperature and stress dependencies of SAW signal were also investigated in the non-sputtered film state. Signal amplitude and phase change of SAW were chosen to measure as the sensing parameters. As a result, temperature, stress level, phase transformation in SMA depending on temperature and mechanical damage accumulation could be measured by the proposed multi-functional SAW sensor. Moreover, the wireless SAW sensing system which has a unique feature of no supplying electric battery was constructed, and the same characteristic evaluation is confirmed in comparison with wired case.

  13. Evaluation of MPEG-7-Based Audio Descriptors for Animal Voice Recognition over Wireless Acoustic Sensor Networks

    PubMed Central

    Luque, Joaquín; Larios, Diego F.; Personal, Enrique; Barbancho, Julio; León, Carlos

    2016-01-01

    Environmental audio monitoring is a huge area of interest for biologists all over the world. This is why some audio monitoring system have been proposed in the literature, which can be classified into two different approaches: acquirement and compression of all audio patterns in order to send them as raw data to a main server; or specific recognition systems based on audio patterns. The first approach presents the drawback of a high amount of information to be stored in a main server. Moreover, this information requires a considerable amount of effort to be analyzed. The second approach has the drawback of its lack of scalability when new patterns need to be detected. To overcome these limitations, this paper proposes an environmental Wireless Acoustic Sensor Network architecture focused on use of generic descriptors based on an MPEG-7 standard. These descriptors demonstrate it to be suitable to be used in the recognition of different patterns, allowing a high scalability. The proposed parameters have been tested to recognize different behaviors of two anuran species that live in Spanish natural parks; the Epidalea calamita and the Alytes obstetricans toads, demonstrating to have a high classification performance. PMID:27213375

  14. Monolithic integrated system with an electrowetting-on-dielectric actuator and a film-bulk-acoustic-resonator sensor

    NASA Astrophysics Data System (ADS)

    Zhang, Menglun; Cui, Weiwei; Chen, Xuejiao; Wang, Chao; Pang, Wei; Duan, Xuexin; Zhang, Daihua; Zhang, Hao

    2015-02-01

    Although digital microfluidics has shown great potential in a wide range of applications, a lab-on-a-chip with integrated digital droplet actuators and powerful biochemical sensors is still lacking. To address the demand, a fully integrated chip with electrowetting-on-dielectric (EWOD) and a film bulk acoustic resonator (FBAR) sensor is introduced, where an EWOD actuator manipulates digital droplets and the FBAR sensor detects the presence of substances in the droplets, respectively. The piezoelectric layer of the FBAR sensor and the dielectric layer of the EWOD share the same aluminum nitride (AlN) thin film, which is a key factor to achieve the full integration of the two completely different devices. The liquid droplets are reliably managed by the EWOD actuator to sit on or move off the FBAR sensor precisely. Sessile drop experiments and limit of detection (LOD) experiments are carried out to characterize the EWOD actuator and the FBAR sensor, respectively. Taking advantage of the digital droplet operation, a ‘dry sensing mode’ of the FBAR sensor in the lab-on-a-chip microsystem is proposed, which has a much higher signal to noise ratio than the conventional ‘wet sensing mode’. Hg2+ droplets with various concentrations are transported and sensed to demonstrate the capability of the integrated system. The EWOD-FBAR chip is expected to play an important role in many complex lab-on-a-chip applications.

  15. Novel Acoustic Loading of a Mass Spectrometer: Toward Next-Generation High-Throughput MS Screening.

    PubMed

    Sinclair, Ian; Stearns, Rick; Pringle, Steven; Wingfield, Jonathan; Datwani, Sammy; Hall, Eric; Ghislain, Luke; Majlof, Lars; Bachman, Martin

    2016-02-01

    High-throughput, direct measurement of substrate-to-product conversion by label-free detection, without the need for engineered substrates or secondary assays, could be considered the "holy grail" of drug discovery screening. Mass spectrometry (MS) has the potential to be part of this ultimate screening solution, but is constrained by the limitations of existing MS sample introduction modes that cannot meet the throughput requirements of high-throughput screening (HTS). Here we report data from a prototype system (Echo-MS) that uses acoustic droplet ejection (ADE) to transfer femtoliter-scale droplets in a rapid, precise, and accurate fashion directly into the MS. The acoustic source can load samples into the MS from a microtiter plate at a rate of up to three samples per second. The resulting MS signal displays a very sharp attack profile and ions are detected within 50 ms of activation of the acoustic transducer. Additionally, we show that the system is capable of generating multiply charged ion species from simple peptides and large proteins. The combination of high speed and low sample volume has significant potential within not only drug discovery, but also other areas of the industry.

  16. Clinical Studies of Real-Time Monitoring of Lithotripter Performance Using Passive Acoustic Sensors

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

    ), comparison of the opinion of the urologist at follow-up with the acoustically derived judgment identified a good correlation (kappa = 0.94), the device demonstrating a sensitivity of 91.7% (in that it correctly predicted 11 of the 12 treatments which the urologist stated had been `successful' at the 3-week follow-up), and a specificity of 100% (in that it correctly predicted all of the 37 treatments which the urologist stated had been `unsuccessful' at the 3-week follow-up). The `gold standard' opinion of the urologist (CTS2) correlated poorly (kappa = 0.38) with the end-of-treatment opinion of the radiographer (CTS1). This is due to the limited resolution of the lithotripter X-Ray fluoroscopy system. If the results of phase 1 and phase 2 are pooled to form a dataset against which retrospectively to test the rules drawn up in phase 1, when compared with the gold standard CTS2, over the two clinical trials (79 patients) the device-derived scored (TS0) correctly predicted the clinical effectiveness of the treatment for 78 for the 79 patients (the error occurred on a difficult patient with a high body mass index). In comparison, using the currently available technology the in-theatre clinician (the radiographer) provided a treatment score CTS1 which correctly predicted the outcome of only 61 of the 79 therapies. In particular the passive acoustic device correctly predicted 18 of the 19 treatments that were successful (i.e. 94.7 sensitivity), whilst the current technology enabled the in-theatre radiographer to predict only 7 of the 19 successful treatments (i.e. 36.8 sensitivity). The real-time capabilities of the device were used in a preliminary examination of the effect of ventilation.

  17. Characterization of the HIV-1 TAR RNA-Tat peptide and drug interactions by on-line acoustic wave sensor

    NASA Astrophysics Data System (ADS)

    Tassew, Nardos Gobena

    This thesis presents the application of the thickness shear-mode (TSM) acoustic wave sensor to the study of RNA-protein and RNA-drug interactions at the solid-liquid interface. The binding of the human immunodeficiency virus-type 1 Tat protein to the trans-activation responsive RNA element (TAR) has been studied using this sensor. Data from such measurements show that the sensor is able to discriminate between different Tat peptides derived from the parent protein based on size. The effects of mutations introduced at specific sites in the protein and RNA on the TAR-Tat binding have also been examined in detail. Reduced level of response in acoustic parameters due to mutations was observed indicating that the decrease in binding in response to site specific mutations can be acoustically detected. Data from acoustic wave sensor measurements indicate that the TAR-Tat binding is also affected by ionic strength. Both the frequency and motional resistance signals show periodic responses when varying concentrations of salt are introduced on a TAR-modified surface. The binding of the two molecules seems to be a function of the response of the nucleic acid to salt concentrations. The kinetics of binding of Tat peptides to TAR RNA and to a bulge mutant analogue (MTAR) is also examined from the rate of change of the series resonant frequency. Results from such analysis illustrate longer Tat peptides formed more stable complexes with TAR RNA and exhibited increased discrimination between mutant and wild type TAR. The binding of two aminoglycoside antibiotics, neomycin and streptomycin, to TAR RNA and their effectiveness in preventing TAR-Tat complex formation has been studied in detail. Binding affinity is directly correlated with the inhibitory potency of these molecules and the TSM sensor shows that neomycin exhibits at least a ten fold greater affinity to TAR and that it is also a more potent inhibitor than streptomycin. The results from this research involving TAR-Tat and

  18. Exploring bubble oscillation and mass transfer enhancement in acoustic-assisted liquid-liquid extraction with a microfluidic device

    PubMed Central

    Xie, Yuliang; Chindam, Chandraprakash; Nama, Nitesh; Yang, Shikuan; Lu, Mengqian; Zhao, Yanhui; Mai, John D.; Costanzo, Francesco; Huang, Tony Jun

    2015-01-01

    We investigated bubble oscillation and its induced enhancement of mass transfer in a liquid-liquid extraction process with an acoustically-driven, bubble-based microfluidic device. The oscillation of individually trapped bubbles, of known sizes, in microchannels was studied at both a fixed frequency, and over a range of frequencies. Resonant frequencies were analytically identified and were found to be in agreement with the experimental observations. The acoustic streaming induced by the bubble oscillation was identified as the cause of this enhanced extraction. Experiments extracting Rhodanmine B from an aqueous phase (DI water) to an organic phase (1-octanol) were performed to determine the relationship between extraction efficiency and applied acoustic power. The enhanced efficiency in mass transport via these acoustic-energy-assisted processes was confirmed by comparisons against a pure diffusion-based process. PMID:26223474

  19. Exploring bubble oscillation and mass transfer enhancement in acoustic-assisted liquid-liquid extraction with a microfluidic device

    NASA Astrophysics Data System (ADS)

    Xie, Yuliang; Chindam, Chandraprakash; Nama, Nitesh; Yang, Shikuan; Lu, Mengqian; Zhao, Yanhui; Mai, John D.; Costanzo, Francesco; Huang, Tony Jun

    2015-07-01

    We investigated bubble oscillation and its induced enhancement of mass transfer in a liquid-liquid extraction process with an acoustically-driven, bubble-based microfluidic device. The oscillation of individually trapped bubbles, of known sizes, in microchannels was studied at both a fixed frequency, and over a range of frequencies. Resonant frequencies were analytically identified and were found to be in agreement with the experimental observations. The acoustic streaming induced by the bubble oscillation was identified as the cause of this enhanced extraction. Experiments extracting Rhodanmine B from an aqueous phase (DI water) to an organic phase (1-octanol) were performed to determine the relationship between extraction efficiency and applied acoustic power. The enhanced efficiency in mass transport via these acoustic-energy-assisted processes was confirmed by comparisons against a pure diffusion-based process.

  20. The Search for Acoustically-Driven Mass-Loss in Evolved Stars

    NASA Astrophysics Data System (ADS)

    Stencel, R. E.; Brown, A.; Carpenter, K. G.; Cuntz, M.; Judge, P.

    1992-12-01

    Recent ab-initio calculations of stochastic stellar wind models by Cuntz (1992 in Cool Stars VII, ASP Conf. Ser. 26, p.383) have proven remarkably robust in predicting observed chromospheric flow patterns including possible variabilities with time in selected cool, evolved stars. The calculations solve the equations of hydrodynamics using the method of characteristics and assume: (i) saw-tooth shock wave profiles, and (ii) wave periods were changed stochastically while keeping the wave amplitudes constant (see Cuntz 1990 Ap.J. 349, p.141). Among the results of fitting chromospheric flow velocities is the implication that the permitted range of acoustic wave periods for a given star is constrained. We made use of the IUE satellite during August and September 1992 to repeatedly observe two stars, the yellow giant Aldebaran (K5 III) and the red supergiant, Betelgeuse (M2 Iab), in order to sample variations in their atmospheres on timescales of ~ 10(4) to ~ 10(6) seconds, which bracket the predicted mean acoustic wave periods for these objects. In particular, we obtained deep exposures in order to measure density-sensitive line ratios within the C II] intercombination features near 2325A (cf. Lennon et al. 1985 Ap.J. 294, p.200) to test the hypothesis that density fluctuations could be measured as a consequence of these acoustic waves. The results of these observations will be presented and discussed in terms of the number and amplitude of acoustic waves contributing to chromospheric heating and mass loss from these stars, as well as the wave origins in the evolving oscillatory structure of these stellar interiors. We are pleased to acknowledge IUE--NASA grant NAG5-2103 for partial support of this effort.

  1. A comparative evaluation of piezoelectric sensors for acoustic emission-based impact location estimation and damage classification in composite structures

    NASA Astrophysics Data System (ADS)

    Uprety, Bibhisha; Kim, Sungwon; Mathews, V. John; Adams, Daniel O.

    2015-03-01

    Acoustic Emission (AE) based Structural Health Monitoring (SHM) is of great interest for detecting impact damage in composite structures. Within the aerospace industry the need to detect and locate these events, even when no visible damage is present, is important both from the maintenance and design perspectives. In this investigation, four commercially available piezoelectric sensors were evaluated for usage in an AE-based SHM system. Of particular interest was comparing the acoustic response of the candidate piezoelectric sensors for impact location estimations as well as damage classification resulting from the impact in fiber-reinforced composite structures. Sensor assessment was performed based on response signal characterization and performance for active testing at 300 kHz and steel-ball drop testing using both aluminum and carbon/epoxy composite plates. Wave mode velocities calculated from the measured arrival times were found to be in good agreement with predictions obtained using both the Disperse code and finite element analysis. Differences in the relative strength of the received wave modes, the overall signal strengths and signal-to-noise ratios were observed through the use of both active testing as well as passive steel-ball drop testing. Further comparative is focusing on assessing AE sensor performance for use in impact location estimation algorithms as well as detecting and classifying damage produced in composite structures due to impact events.

  2. Detecting trihalomethanes using nanoporous-carbon coated surface-acoustic-wave sensors

    DOE PAGES

    Siegal, Michael P.; Mowry, Curtis D.; Pfeifer, Kent B.; ...

    2015-03-07

    We study nanoporous-carbon (NPC) grown via pulsed laser deposition (PLD) as a sorbent coating on 96.5-MHz surface-acoustic-wave (SAW) devices to detect trihalomethanes (THMs), regulated byproducts from the chemical treatment of drinking water. Using both insertion-loss and isothermal-response measurements from known quantities of chloroform, the highest vapor pressure THM, we optimize the NPC mass-density at 1.05 ± 0.08 g/cm3 by controlling the background argon pressure during PLD. Precise THM quantities in a chlorobenzene solvent are directly injected into a separation column and detected as the phase-angle shift of the SAW device output compared to the drive signal. Using optimized NPC-coated SAWs,more » we study the chloroform response as a function of operating temperatures ranging from 10–50°C. Finally, we demonstrate individual responses from complex mixtures of all four THMs, with masses ranging from 10–2000 ng, after gas chromatography separation. As a result, estimates for each THM detection limit using a simple peak-height response evaluation are 4.4 ng for chloroform and 1 ng for bromoform; using an integrated-peak area response analysis improves the detection limits to 0.73 ng for chloroform and 0.003 ng bromoform.« less

  3. Detecting trihalomethanes using nanoporous-carbon coated surface-acoustic-wave sensors

    SciTech Connect

    Siegal, Michael P.; Mowry, Curtis D.; Pfeifer, Kent B.; Gallis, Dorina F. S.

    2015-03-07

    We study nanoporous-carbon (NPC) grown via pulsed laser deposition (PLD) as a sorbent coating on 96.5-MHz surface-acoustic-wave (SAW) devices to detect trihalomethanes (THMs), regulated byproducts from the chemical treatment of drinking water. Using both insertion-loss and isothermal-response measurements from known quantities of chloroform, the highest vapor pressure THM, we optimize the NPC mass-density at 1.05 ± 0.08 g/cm3 by controlling the background argon pressure during PLD. Precise THM quantities in a chlorobenzene solvent are directly injected into a separation column and detected as the phase-angle shift of the SAW device output compared to the drive signal. Using optimized NPC-coated SAWs, we study the chloroform response as a function of operating temperatures ranging from 10–50°C. Finally, we demonstrate individual responses from complex mixtures of all four THMs, with masses ranging from 10–2000 ng, after gas chromatography separation. As a result, estimates for each THM detection limit using a simple peak-height response evaluation are 4.4 ng for chloroform and 1 ng for bromoform; using an integrated-peak area response analysis improves the detection limits to 0.73 ng for chloroform and 0.003 ng bromoform.

  4. Mercury Sorption and Desorption on Gold: A Comparative Analysis of Surface Acoustic Wave and Quartz Crystal Microbalance-Based Sensors.

    PubMed

    Kabir, K M Mohibul; Sabri, Ylias M; Esmaielzadeh Kandjani, Ahmad; Matthews, Glenn I; Field, Matthew; Jones, Lathe A; Nafady, Ayman; Ippolito, Samuel J; Bhargava, Suresh K

    2015-08-04

    Microelectromechanical sensors based on surface acoustic wave (SAW) and quartz crystal microbalance (QCM) transducers possess substantial potential as online elemental mercury (Hg(0)) vapor detectors in industrial stack effluents. In this study, a comparison of SAW- and QCM-based sensors is performed for the detection of low concentrations of Hg(0) vapor (ranging from 24 to 365 ppbv). Experimental measurements and finite element method (FEM) simulations allow the comparison of these sensors with regard to their sensitivity, sorption and desorption characteristics, and response time following Hg(0) vapor exposure at various operating temperatures ranging from 35 to 75 °C. Both of the sensors were fabricated on quartz substrates (ST and AT cut quartz for SAW and QCM devices, respectively) and employed thin gold (Au) layers as the electrodes. The SAW-based sensor exhibited up to ∼111 and ∼39 times higher response magnitudes than did the QCM-based sensor at 35 and 55 °C, respectively, when exposed to Hg(0) vapor concentrations ranging from 24 to 365 ppbv. The Hg(0) sorption and desorption calibration curves of both sensors were found to fit well with the Langmuir extension isotherm at different operating temperatures. Furthermore, the Hg(0) sorption and desorption rate demonstrated by the SAW-based sensor was found to decrease as the operating temperature increased, while the opposite trend was observed for the QCM-based sensor. However, the SAW-based sensor reached the maximum Hg(0) sorption rate faster than the QCM-based sensor regardless of operating temperature, whereas both sensors showed similar response times (t90) at various temperatures. Additionally, the sorption rate data was utilized in this study in order to obtain a faster response time from the sensor upon exposure to Hg(0) vapor. Furthermore, comparative analysis of the developed sensors' selectivity showed that the SAW-based sensor had a higher overall selectivity (90%) than did the QCM

  5. Reflectance Infrared Spectroscopy on Operating Surface Acoustic Wave Chemical Sensors During Exposure to Gas-Phase Analytes

    SciTech Connect

    Hierlemann, A.; Hill, M.; Ricco, A.J.; Staton, A.W.; Thomas, R.C.

    1999-01-11

    We have developed instrumentation to enable the combination of surface acoustic wave (SAW) sensor measurements with direct, in-situ molecular spectroscopic measurements to understand the response of the SAW sensors with respect to the interfacial chemistry of surface-confined sensing films interacting with gas-phase analytes. Specifically, the instrumentation and software was developed to perform in-situ Fourier-transform infrared external-reflectance spectroscopy (FTIR-ERS) on operating SAW devices during dosing of their chemically modified surfaces with analytes. By probing the surface with IR spectroscopy during gas exposure, it is possible to understand in unprecedented detail the interaction processes between the sorptive SAW coatings and the gaseous analyte molecules. In this report, we provide details of this measurement system, and also demonstrate the utility of these combined measurements by characterizing the SAW and FTIR-ERS responses of organic thin-film sensor coatings interacting with gas-phase analytes.

  6. Thin-layer chromatography/laser-induced acoustic desorption/electrospray ionization mass spectrometry.

    PubMed

    Cheng, Sy-Chyi; Huang, Min-Zong; Shiea, Jentaie

    2009-11-15

    The combination of laser-induced acoustic desorption and electrospray ionization mass spectrometry (LIAD/ESI/MS) can be used to rapidly characterize chemical compounds separated on a thin layer chromatography (TLC) plate. We performed LIAD analysis by irradiating the rear side of an aluminum-based TLC plate with a pulsed infrared (IR) laser. To efficiently generate and transfer acoustic and shock waves to ablate the analyte-containing TLC gels, a glass slide was attached to the rear of the TLC plate and the gap between the glass slide and the TLC plate was filled with a viscous solution (glycerol). Although the diameter of the laser spot created on the rear of the TLC plate was approximately 0.35 mm, the ablated areas on the front sides of the silica gel bed and the C(18) reverse-phase gel bed had diameters of approximately 1.3 and 3 mm, respectively. The ablated analyte molecules were ionized in an ESI plume and then detected by an ion trap mass analyzer. This TLC/LIAD/ESI/MS approach allowed the components in mixtures of dye standards, drug standards, and rosemary essential oil to be separated and rapidly characterized.

  7. Feasibility study of using smart aggregates as embedded acoustic emission sensors for health monitoring of concrete structures

    NASA Astrophysics Data System (ADS)

    Li, Weijie; Kong, Qingzhao; Ho, Siu Chun Michael; Lim, Ing; Mo, Y. L.; Song, Gangbing

    2016-11-01

    Acoustic emission (AE) is a nondestructive evaluation technique that is capable of monitoring the damage evolution of concrete structures in real time. Conventionally, AE sensors are surface mounted on the host structures, however, the AE signals attenuate quickly due to the high attenuation properties of concrete structures. This study conducts a feasibility study of using smart aggregates (SAs), which are a type of embedded piezoceramic transducers, as embedded AE sensors for the health monitoring of concrete structures. A plain concrete beam with two surface mounted AE sensors and two embedded SAs was fabricated in laboratory and loaded under a designed three-point-bending test. The performance of embedded SAs were compared with the traditional surface mounted AE sensors in their ability to detect and evaluate the damage to the concrete structure. The results verified the feasibility of using smart aggregates as embedded AE sensors for monitoring structural damage in concrete. Potentially, the low cost smart aggregates could function as embedded AE sensors, providing great sensitivity and high reliability in applications for the structural health monitoring of concrete structures.

  8. Improved Maturity and Ripeness Classifications of Magnifera Indica cv. Harumanis Mangoes through Sensor Fusion of an Electronic Nose and Acoustic Sensor

    PubMed Central

    Zakaria, Ammar; Shakaff, Ali Yeon Md; Masnan, Maz Jamilah; Saad, Fathinul Syahir Ahmad; Adom, Abdul Hamid; Ahmad, Mohd Noor; Jaafar, Mahmad Nor; Abdullah, Abu Hassan; Kamarudin, Latifah Munirah

    2012-01-01

    In recent years, there have been a number of reported studies on the use of non-destructive techniques to evaluate and determine mango maturity and ripeness levels. However, most of these reported works were conducted using single-modality sensing systems, either using an electronic nose, acoustics or other non-destructive measurements. This paper presents the work on the classification of mangoes (Magnifera Indica cv. Harumanis) maturity and ripeness levels using fusion of the data of an electronic nose and an acoustic sensor. Three groups of samples each from two different harvesting times (week 7 and week 8) were evaluated by the e-nose and then followed by the acoustic sensor. Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were able to discriminate the mango harvested at week 7 and week 8 based solely on the aroma and volatile gases released from the mangoes. However, when six different groups of different maturity and ripeness levels were combined in one classification analysis, both PCA and LDA were unable to discriminate the age difference of the Harumanis mangoes. Instead of six different groups, only four were observed using the LDA, while PCA showed only two distinct groups. By applying a low level data fusion technique on the e-nose and acoustic data, the classification for maturity and ripeness levels using LDA was improved. However, no significant improvement was observed using PCA with data fusion technique. Further work using a hybrid LDA-Competitive Learning Neural Network was performed to validate the fusion technique and classify the samples. It was found that the LDA-CLNN was also improved significantly when data fusion was applied. PMID:22778629

  9. Meta-atom cluster acoustic metamaterial with broadband negative effective mass density

    SciTech Connect

    Chen, Huaijun; Zhai, Shilong; Ding, Changlin; Liu, Song; Luo, Chunrong; Zhao, Xiaopeng

    2014-02-07

    We design a resonant meta-atom cluster, via which a two-dimensional (2D) acoustic metamaterial (AM) with broadband negative effective mass density from 1560 Hz to 5580 Hz is fabricated. Experimental results confirm that there is only weak interaction among the meta-atoms in the cluster. And then the meta-atoms in the cluster independently resonate, resulting in the cluster becoming equivalent to a broadband resonance unit. Extracted effective refractive indices from reflection and transmission measurements of the 2D AM appear to be negative from 1500 Hz to 5480 Hz. The broadband negative refraction has also been demonstrated by our further experiments. We expect that this meta-atom cluster AM will significantly contribute to the design of broadband negative effective mass density AM.

  10. Perturbation of mass accretion rate, associated acoustic geometry and stability analysis

    NASA Astrophysics Data System (ADS)

    Bollimpalli, Deepika A.; Bhattacharya, Sourav; Das, Tapas K.

    2017-02-01

    We investigate the stability of stationary integral solutions of an ideal irrotational fluid in a general static and spherically symmetric background, by studying the profile of the perturbation of the mass accretion rate. We consider low angular momentum axisymmetric accretion flows for three different accretion disk models and consider time dependent and radial linear perturbation of the mass accretion rate. First we show that the propagation of such perturbation can be determined by an effective 2 × 2 matrix, which has qualitatively similar acoustic causal properties as one obtains via the perturbation of the velocity potential. Next, using this matrix we analytically address the stability issues, for both standing and travelling wave configurations generated by the perturbation. Finally, based on this general formalism we briefly discuss the explicit example of the Schwarzschild spacetime and compare our results of stability with the existing literature, which instead address this problem via the perturbation of the velocity potential.

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

    PubMed Central

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

    2016-01-01

    Monitoring ocean acoustic noise has been the subject of considerable recent study, motivated by the desire to assess the impact of anthropogenic noise on marine life. A combination of measuring ocean sound using an acoustic sensor network and modelling sources of sound and sound propagation has been proposed as an approach to estimating the acoustic noise map within a region of interest. However, strategies for developing a monitoring network are not well established. In this paper, considerations for designing a network are investigated using a simulated scenario based on the measurement of sound from ships in a shipping lane. Using models for the sources of the sound and for sound propagation, a noise map is calculated and measurements of the noise map by a sensor network within the region of interest are simulated. A compressive sensing algorithm, which exploits the sparsity of the representation of the noise map in terms of the sources, is used to estimate the locations and levels of the sources and thence the entire noise map within the region of interest. It is shown that although the spatial resolution to which the sound sources can be identified is generally limited, estimates of aggregated measures of the noise map can be obtained that are more reliable compared with those provided by other approaches. PMID:27011187

  12. The mass load effect on the resonant acoustic frequencies of colloidal semiconductor nanoplatelets

    NASA Astrophysics Data System (ADS)

    Girard, Adrien; Saviot, Lucien; Pedetti, Silvia; Tessier, Mickaël D.; Margueritat, Jérémie; Gehan, Hélène; Mahler, Benoit; Dubertret, Benoit; Mermet, Alain

    2016-07-01

    Resonant acoustic modes of ultrathin CdS and CdSe colloidal nanoplatelets (NPLs) with varying thicknesses were probed using low frequency Raman scattering. The spectra are dominated by an intense band ascribed to the thickness breathing mode of the 2D nanostructures. The measured Raman frequencies show strong deviations with respect to the values expected for simple bare plates, all the more so as the thickness is reduced. The deviation is shown to arise from the additional mass of the organic ligands that are bound to the free surfaces of the nanoplatelets. The calculated eigen frequencies of vibrating platelets weighed down by the mass of the organic ligands are in very good agreement with the observed experimental behaviours. This finding opens up a new possibility of nanomechanical sensing such as nanobalances.Resonant acoustic modes of ultrathin CdS and CdSe colloidal nanoplatelets (NPLs) with varying thicknesses were probed using low frequency Raman scattering. The spectra are dominated by an intense band ascribed to the thickness breathing mode of the 2D nanostructures. The measured Raman frequencies show strong deviations with respect to the values expected for simple bare plates, all the more so as the thickness is reduced. The deviation is shown to arise from the additional mass of the organic ligands that are bound to the free surfaces of the nanoplatelets. The calculated eigen frequencies of vibrating platelets weighed down by the mass of the organic ligands are in very good agreement with the observed experimental behaviours. This finding opens up a new possibility of nanomechanical sensing such as nanobalances. Electronic supplementary information (ESI) available. See DOI: 10.1039/C5NR07383A

  13. Underwater Wireless Sensor Networks: How Do Acoustic Propagation Models Impact the Performance of Higher-Level Protocols?

    PubMed Central

    Llor, Jesús; Malumbres, Manuel P.

    2012-01-01

    Several Medium Access Control (MAC) and routing protocols have been developed in the last years for Underwater Wireless Sensor Networks (UWSNs). One of the main difficulties to compare and validate the performance of different proposals is the lack of a common standard to model the acoustic propagation in the underwater environment. In this paper we analyze the evolution of underwater acoustic prediction models from a simple approach to more detailed and accurate models. Then, different high layer network protocols are tested with different acoustic propagation models in order to determine the influence of environmental parameters on the obtained results. After several experiments, we can conclude that higher-level protocols are sensitive to both: (a) physical layer parameters related to the network scenario and (b) the acoustic propagation model. Conditions like ocean surface activity, scenario location, bathymetry or floor sediment composition, may change the signal propagation behavior. So, when designing network architectures for UWSNs, the role of the physical layer should be seriously taken into account in order to assert that the obtained simulation results will be close to the ones obtained in real network scenarios. PMID:22438712

  14. Design and implementation of low complexity wake-up receiver for underwater acoustic sensor networks

    NASA Astrophysics Data System (ADS)

    Yue, Ming

    This thesis designs a low-complexity dual Pseudorandom Noise (PN) scheme for identity (ID) detection and coarse frame synchronization. The two PN sequences for a node are identical and are separated by a specified length of gap which serves as the ID of different sensor nodes. The dual PN sequences are short in length but are capable of combating severe underwater acoustic (UWA) multipath fading channels that exhibit time varying impulse responses up to 100 taps. The receiver ID detection is implemented on a microcontroller MSP430F5529 by calculating the correlation between the two segments of the PN sequence with the specified separation gap. When the gap length is matched, the correlator outputs a peak which triggers the wake-up enable. The time index of the correlator peak is used as the coarse synchronization of the data frame. The correlator is implemented by an iterative algorithm that uses only one multiplication and two additions for each sample input regardless of the length of the PN sequence, thus achieving low computational complexity. The real-time processing requirement is also met via direct memory access (DMA) and two circular buffers to accelerate data transfer between the peripherals and the memory. The proposed dual PN detection scheme has been successfully tested by simulated fading channels and real-world measured channels. The results show that, in long multipath channels with more than 60 taps, the proposed scheme achieves high detection rate and low false alarm rate using maximal-length sequences as short as 31 bits to 127 bits, therefore it is suitable as a low-power wake-up receiver. The future research will integrate the wake-up receiver with Digital Signal Processors (DSP) for payload detection.

  15. An Improved Azimuth Angle Estimation Method with a Single Acoustic Vector Sensor Based on an Active Sonar Detection System.

    PubMed

    Zhao, Anbang; Ma, Lin; Ma, Xuefei; Hui, Juan

    2017-02-20

    In this paper, an improved azimuth angle estimation method with a single acoustic vector sensor (AVS) is proposed based on matched filtering theory. The proposed method is mainly applied in an active sonar detection system. According to the conventional passive method based on complex acoustic intensity measurement, the mathematical and physical model of this proposed method is described in detail. The computer simulation and lake experiments results indicate that this method can realize the azimuth angle estimation with high precision by using only a single AVS. Compared with the conventional method, the proposed method achieves better estimation performance. Moreover, the proposed method does not require complex operations in frequencydomain and achieves computational complexity reduction.

  16. An ultra-low power and flexible acoustic modem design to develop energy-efficient underwater sensor networks.

    PubMed

    Sánchez, Antonio; Blanc, Sara; Yuste, Pedro; Perles, Angel; Serrano, Juan José

    2012-01-01

    This paper is focused on the description of the physical layer of a new acoustic modem called ITACA. The modem architecture includes as a major novelty an ultra-low power asynchronous wake-up system implementation for underwater acoustic transmission that is based on a low-cost off-the-shelf RFID peripheral integrated circuit. This feature enables a reduced power dissipation of 10 μW in stand-by mode and registers very low power values during reception and transmission. The modem also incorporates clear channel assessment (CCA) to support CSMA-based medium access control (MAC) layer protocols. The design is part of a compact platform for a long-life short/medium range underwater wireless sensor network.

  17. Acoustic Emission Detection of Macro-Cracks on Engraving Tool Steel Inserts during the Injection Molding Cycle Using PZT Sensors

    PubMed Central

    Svečko, Rajko; Kusić, Dragan; Kek, Tomaž; Sarjaš, Andrej; Hančič, Aleš; Grum, Janez

    2013-01-01

    This paper presents an improved monitoring system for the failure detection of engraving tool steel inserts during the injection molding cycle. This system uses acoustic emission PZT sensors mounted through acoustic waveguides on the engraving insert. We were thus able to clearly distinguish the defect through measured AE signals. Two engraving tool steel inserts were tested during the production of standard test specimens, each under the same processing conditions. By closely comparing the captured AE signals on both engraving inserts during the filling and packing stages, we were able to detect the presence of macro-cracks on one engraving insert. Gabor wavelet analysis was used for closer examination of the captured AE signals' peak amplitudes during the filling and packing stages. The obtained results revealed that such a system could be used successfully as an improved tool for monitoring the integrity of an injection molding process. PMID:23673677

  18. An Improved Azimuth Angle Estimation Method with a Single Acoustic Vector Sensor Based on an Active Sonar Detection System

    PubMed Central

    Zhao, Anbang; Ma, Lin; Ma, Xuefei; Hui, Juan

    2017-01-01

    In this paper, an improved azimuth angle estimation method with a single acoustic vector sensor (AVS) is proposed based on matched filtering theory. The proposed method is mainly applied in an active sonar detection system. According to the conventional passive method based on complex acoustic intensity measurement, the mathematical and physical model of this proposed method is described in detail. The computer simulation and lake experiments results indicate that this method can realize the azimuth angle estimation with high precision by using only a single AVS. Compared with the conventional method, the proposed method achieves better estimation performance. Moreover, the proposed method does not require complex operations in frequency-domain and achieves computational complexity reduction. PMID:28230763

  19. Surface Acoustic Wave Based Pressure Sensor with Ground Shielding over Cavity on 41° YX LiNbO3

    NASA Astrophysics Data System (ADS)

    Lee, Keekeun; Wang, Wen; Kim, Geunyoung; Yang, Sangsik

    2006-07-01

    A surface acoustic wave (SAW)-based pressure sensor was fabricated for stable mechanical compression force measurement. A single phase unidirectional transducer (SPUDT) and two acoustic tracks were employed to minimize inherent insertion loss and improve reflectivity from the reflectors. The coupling of modes (COM) theory and finite element methods (FEMs) were used to determine optimal design parameters. A LiNbO3 diaphragm was bonded to a heavily doped silicon substrate with a cavity of ˜250 μm deep, in which gold was lined all over the inner cavity to reduce the coupling loss of SAW energy to the surrounding atmosphere. As a mechanical compression force was applied to the diaphragm, the diaphragm bent, resulting in phase shifts of the reflected peaks. The phase shifts were modulated depending on the amount of mechanical compression applied. The measured reflection coefficient S11 showed good agreement with simulated results.

  20. An Ultra-Low Power and Flexible Acoustic Modem Design to Develop Energy-Efficient Underwater Sensor Networks

    PubMed Central

    Sánchez, Antonio; Blanc, Sara; Yuste, Pedro; Perles, Angel; Serrano, Juan José

    2012-01-01

    This paper is focused on the description of the physical layer of a new acoustic modem called ITACA. The modem architecture includes as a major novelty an ultra-low power asynchronous wake-up system implementation for underwater acoustic transmission that is based on a low-cost off-the-shelf RFID peripheral integrated circuit. This feature enables a reduced power dissipation of 10 μW in stand-by mode and registers very low power values during reception and transmission. The modem also incorporates clear channel assessment (CCA) to support CSMA-based medium access control (MAC) layer protocols. The design is part of a compact platform for a long-life short/medium range underwater wireless sensor network. PMID:22969324

  1. 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

  2. The Feasibility of Generalized Acoustic Sensor Operator Training. Final Report for Period February 1974-February 1975.

    ERIC Educational Resources Information Center

    Daniels, Richard W.; Alden, David G.

    The feasibility of generalized approaches to training military personnel in the use of different types of sonar/acoustic warfare systems was explored. The initial phase of the project consisted of the analysis of representative sonar and acoustic equipment to identify training areas and operator performance requirements that could be subjected to…

  3. Cheap DECAF: Density Estimation for Cetaceans from Acoustic Fixed Sensors Using Separate, Non-Linked Devices

    DTIC Science & Technology

    2011-09-30

    whale (Balaenoptera physalus) from a sparse array of ocean bottom seismometers (OBSs) will be the dataset used to develop and test a variety of density...T. Marques. 2009. Taming the Jez monster : Estimating fin whale spatial density using acoustic propagation modeling. J. Acoust. Soc. Am. 126(4):2229

  4. Indoor localization for global information service using acoustic wireless sensor network

    NASA Astrophysics Data System (ADS)

    Desai, Pratikkumar; Baine, Nicholas; Rattan, Kuldip S.

    2011-06-01

    Indoor localization with sensing capabilities is the missing link for a Geospatial Information System and sensor web. The sensor network is capable of environmental monitoring and geo-tagging sensor data. This paper presents a unique algorithm which uses fusion of Radio Signal Strength Indicator and Time Difference of Arrival for centimeter level accurate indoor localization using wireless sensor network motes. The paper also proposes the integration of various environmental sensors with wireless sensor network. The acquired sensor data can be geo-tagged with the translated global coordinates and additional sensory metadata. With the use of semantic sensor web, this sensor information can be utilized in various decision making scenarios for critical situations. The main goal of the paper is to use indoor localization assisted by sensor fusion and semantic web for first responders in emergency scenarios.

  5. Effects of internal mass distribution and its isolation on the acoustic characteristics of a submerged hull

    NASA Astrophysics Data System (ADS)

    Peters, Herwig; Kinns, Roger; Kessissoglou, Nicole

    2014-03-01

    The primary aim of machinery isolation in marine vessels is to isolate structural vibration of the onboard machinery from the hull and to reduce far-field radiation of underwater noise. A substantial proportion of the total submarine mass is on flexible mounts that isolate supported masses from the hull at frequencies above the mounting system resonant frequency. This reduces the dynamically effective mass of the hull and affects the signature of the marine vessel due to propeller excitation. A fully coupled finite element/boundary element (FE/BE) model has been developed to investigate the effect of mass distribution and isolation in a submerged hull. The finite element model of the structure includes internal structures to represent the machinery and other flexibly mounted components. Changes in the radiated sound power demonstrate the effect of machinery isolation on the acoustic signature of the submerged hull due to the external propeller forces. Results are also presented to show how the arrangement of flexible mounts for a large internal structure can influence the radiation due to machinery forces.

  6. Barrow real-time sea ice mass balance data: ingestion, processing, dissemination and archival of multi-sensor data

    NASA Astrophysics Data System (ADS)

    Grimes, J.; Mahoney, A. R.; Heinrichs, T. A.; Eicken, H.

    2012-12-01

    Sensor data can be highly variable in nature and also varied depending on the physical quantity being observed, sensor hardware and sampling parameters. The sea ice mass balance site (MBS) operated in Barrow by the University of Alaska Fairbanks (http://seaice.alaska.edu/gi/observatories/barrow_sealevel) is a multisensor platform consisting of a thermistor string, air and water temperature sensors, acoustic altimeters above and below the ice and a humidity sensor. Each sensor has a unique specification and configuration. The data from multiple sensors are combined to generate sea ice data products. For example, ice thickness is calculated from the positions of the upper and lower ice surfaces, which are determined using data from downward-looking and upward-looking acoustic altimeters above and below the ice, respectively. As a data clearinghouse, the Geographic Information Network of Alaska (GINA) processes real time data from many sources, including the Barrow MBS. Doing so requires a system that is easy to use, yet also offers the flexibility to handle data from multisensor observing platforms. In the case of the Barrow MBS, the metadata system needs to accommodate the addition of new and retirement of old sensors from year to year as well as instrument configuration changes caused by, for example, spring melt or inquisitive polar bears. We also require ease of use for both administrators and end users. Here we present the data and processing steps of using sensor data system powered by the NoSQL storage engine, MongoDB. The system has been developed to ingest, process, disseminate and archive data from the Barrow MBS. Storing sensor data in a generalized format, from many different sources, is a challenging task, especially for traditional SQL databases with a set schema. MongoDB is a NoSQL (not only SQL) database that does not require a fixed schema. There are several advantages using this model over the traditional relational database management system (RDBMS

  7. geoPebble: Combined Seismic, Acoustic, and GPS Sensor with Wireless Communications for Glaciological Applications

    NASA Astrophysics Data System (ADS)

    Anandakrishnan, S.; Burkett, P. G.; Long, B.

    2009-12-01

    Glaciologist and geophysicists study many dynamic processes in glaciated environments such as sliding, crevasse formation, and water flow. These processes generate signals that can be interpreted for fundamental parameters needed for numerical models of glacier and ice sheet flow. These signals include microearthquakes beneath glaciers and ice streams during stick-slip processes; seismically identifiable harmonic tremors associated with subglacial water flow; supraglacial lake drainage which can produce rapid uplift of the 1 m/hr. In addition, researchers use active seismic experiments to determine bed properties such as roughness and lubrication. Currently, each process requires different instrumentation and/or different field equipment to collect the data such as a GPS receiver for displacement, a passive seismic instrument for microearthquakes, and a multichannel seismic recorder for active seismic experiments. We report on the development of an instrument specifically designed for observing dynamic glaciated environments in a single platform, reducing the need for multiple field systems and reducing the cost considerably. The geoPebble wireless seismic acquisition system, designed and built at the Pennsylvania State University, comprises 4 channels of 24-bit seismic and acoustic digitizing, an L1 GPS engine, onboard data storage and an 802.15 ZigBee radio. Three of the four ADC channels are intended to be used with a 3 component seismic sensor. The fourth channel is a dedicated to an audio frequency microphone. The 1 Hz L1 GPS system is capable of horizontal position accuracy to better than 10 cm when post-processed against L1/L2 stations within 10 km. Onboard storage is achieved with a Secure Digital card where volumes now exceed 32 GB. The ZigBee radio is capable of forming a mesh network which reduces transmit and receive power requirements while maintaing communication throughout the array and provides state-of-health information as well as sufficient data

  8. Improving acoustic determinations of the Boltzmann constant with mass spectrometer measurements of the molar mass of argon

    NASA Astrophysics Data System (ADS)

    Yang, Inseok; Pitre, Laurent; Moldover, Michael R.; Zhang, Jintao; Feng, Xiaojuan; Seog Kim, Jin

    2015-10-01

    We determined accurate values of ratios among the average molar masses MAr of 9 argon samples using two completely-independent techniques: (1) mass spectrometry and (2) measured ratios of acoustic resonance frequencies. The two techniques yielded mutually consistent ratios (RMS deviation of 0.16   ×   10-6 MAr from the expected correlation) for the 9 samples of highly-purified, commercially-purchased argon with values of MAr spanning a range of 2   ×   10-6 MAr. Among the 9 argon samples, two were traceable to recent, accurate, argon-based measurements of the Boltzmann constant kB using primary acoustic gas thermometers (AGT). Additionally we determined our absolute values of MAr traceable to two, completely-independent, isotopic-reference standards; one standard was prepared gravimetrically at KRISS in 2006; the other standard was isotopically-enriched 40Ar that was used during NIST’s 1988 measurement of kB and was sent to NIM for this research. The absolute values of MAr determined using the KRISS standard have the relative standard uncertainty ur(MAr)  =  0.70   ×   10-6 (Uncertainties here are one standard uncertainty.); they agree with values of MAr determined at NIM using an AGT within the uncertainty of the comparison ur(MAr)  =  0.93   ×   10-6. If our measurements of MAr are accepted, the difference between two, recent, argon-based, AGT measurements of kB decreases from (2.77   ±   1.43)  ×  10-6 kB to (0.16   ±   1.28)  ×  10-6 kB. This decrease enables the calculation of a meaningful, weighted average value of kB with a uncertainty ur(kB)  ≈  0.6   ×   10-6.

  9. Highly sensitive room-temperature surface acoustic wave (SAW) ammonia sensors based on Co₃O₄/SiO₂ composite films.

    PubMed

    Tang, Yong-Liang; Li, Zhi-Jie; Ma, Jin-Yi; Su, Hai-Qiao; Guo, Yuan-Jun; Wang, Lu; Du, Bo; Chen, Jia-Jun; Zhou, Weilie; Yu, Qing-Kai; Zu, Xiao-Tao

    2014-09-15

    Surface acoustic wave (SAW) sensors based on Co3O4/SiO2 composite sensing films for ammonia detection were investigated at room temperature. The Co3O4/SiO2 composite films were deposited onto ST-cut quartz SAW resonators by a sol-gel method. SEM and AFM characterizations showed that the films had porous structures. The existence of SiO2 was found to enhance the ammonia sensing property of the sensor significantly. The sensor based on a Co3O4/SiO2 composite film, with 50% Co3O4 loading, which had the highest RMS value (3.72), showed the best sensing property. It exhibited a positive frequency shift of 3500 Hz to 1 ppm ammonia as well as excellent selectivity, stability and reproducibility at room temperature. Moreover, a 37% decrease in the conductance of the composite film as well as a positive frequency shift of 12,500 Hz were observed when the sensor was exposed to 20 ppm ammonia, indicating the positive frequency shift was derived from the decrease in film conductance.

  10. Acoustic Source Localization via Time Difference of Arrival Estimation for Distributed Sensor Networks Using Tera-Scale Optical Core Devices

    DOE PAGES

    Imam, Neena; Barhen, Jacob

    2009-01-01

    For real-time acoustic source localization applications, one of the primary challenges is the considerable growth in computational complexity associated with the emergence of ever larger, active or passive, distributed sensor networks. These sensors rely heavily on battery-operated system components to achieve highly functional automation in signal and information processing. In order to keep communication requirements minimal, it is desirable to perform as much processing on the receiver platforms as possible. However, the complexity of the calculations needed to achieve accurate source localization increases dramatically with the size of sensor arrays, resulting in substantial growth of computational requirements that cannot bemore » readily met with standard hardware. One option to meet this challenge builds upon the emergence of digital optical-core devices. The objective of this work was to explore the implementation of key building block algorithms used in underwater source localization on the optical-core digital processing platform recently introduced by Lenslet Inc. This demonstration of considerably faster signal processing capability should be of substantial significance to the design and innovation of future generations of distributed sensor networks.« less

  11. Acoustic emission sensor system using a chirped fiber-Bragg-grating Fabry-Perot interferometer and smart feedback control.

    PubMed

    Zhang, Qi; Zhu, Yupeng; Luo, Xiangyu; Liu, Guigen; Han, Ming

    2017-02-01

    We demonstrate a fiber-optic acoustic emission (AE) sensor system that is capable of performing AE detection, even when the sensor is experiencing large quasi-static strains. The sensor is a Fabry-Perot interferometer formed by cascaded chirped fiber-Bragg gratings (CFBGs). The reflection spectrum of the sensor features a number of narrow spectral notches equally spaced within the reflection bandwidth of the CFBG. A semiconductor laser whose wavelength can be fast tuned through current injection is used to lock the laser line to the center of a slope of a spectral notch. When the notch is knocked out of the tuning range of the laser, a neighboring notch moves into the range. Through a smart feedback control scheme, the laser is unlocked from the current spectral lock and relocked to the desired point of the new notch. The fast speed of the unlocking/relocking process (<1  ms) ensures that the AE signal is monitored without significant disruption.

  12. Flight parameter estimation using instantaneous frequency and direction of arrival measurements from a single acoustic sensor node.

    PubMed

    Lo, Kam W

    2017-03-01

    When an airborne sound source travels past a stationary ground-based acoustic sensor node in a straight line at constant altitude and constant speed that is not much less than the speed of sound in air, the movement of the source during the propagation of the signal from the source to the sensor node (commonly referred to as the "retardation effect") enables the full set of flight parameters of the source to be estimated by measuring the direction of arrival (DOA) of the signal at the sensor node over a sufficiently long period of time. This paper studies the possibility of using instantaneous frequency (IF) measurements from the sensor node to improve the precision of the flight parameter estimates when the source spectrum contains a harmonic line of constant frequency. A simplified Cramer-Rao lower bound analysis shows that the standard deviations in the estimates of the flight parameters can be reduced when IF measurements are used together with DOA measurements. Two flight parameter estimation algorithms that utilize both IF and DOA measurements are described and their performances are evaluated using both simulated data and real data.

  13. Ultrasonic condition monitoring of composite structures using a low-profile acoustic source and an embedded optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Pierce, S. Gareth; Staszewski, Wieslaw J.; Gachagan, Anthony; James, I. R.; Philip, Wayne R.; Worden, Keith; Culshaw, Brian; McNab, Alistair; Tomlinson, Geoffrey R.; Hayward, Gordon

    1997-06-01

    The purpose of this paper is to provide a concise introduction to the developments and recent findings of a BRITE-EURAM program of work (BRE2.CT94-0990 , structurally integrated system for the comprehensive evaluation of composites). The aim of the program has been to develop an acoustic/ultrasonic based structural monitoring system for composite structures using material compatible sensors. Since plate-like structures have been investigated, it has been a requirement to utilize the propagation of ultrasonic Lamb waves through the sample materials. Preliminary investigations utilized conventional piezo-electric sources coupled to the sample via perspex wedges. The Lamb waves generated by these sources were monitored using either a fully embedded or surface mounted optical fiber sensors. The system was tested with a variety of different carbon and glass fiber reinforced panels, and the interaction of the lamb waves with different defects in these materials was monitored. Conventional signal processing allowed the location of defects such as impact damage sites, delaminations and holes. Subsequent investigations have endeavored to refine the system. This paper reports the development of advanced wavelet based signal processing techniques to enhance defect visibility, the optical connectorization of composite panels, and the development of flexible low profile acoustic sources for efficient Lamb wave generation.

  14. Concepts and Development of Bio-Inspired Distributed Embedded Wired/Wireless Sensor Array Architectures for Acoustic Wave Sensing in Integrated Aerospace Vehicles

    NASA Technical Reports Server (NTRS)

    Ghoshal, Anindya; Prosser, William H.; Kirikera, Goutham; Schulz, Mark J.; Hughes, Derke J.; Orisamolu, Wally

    2003-01-01

    This paper discusses the modeling of acoustic emissions in plate structures and their sensing by embedded or surface bonded piezoelectric sensor arrays. Three different modeling efforts for acoustic emission (AE) wave generation and propagation are discussed briefly along with their advantages and disadvantages. Continuous sensors placed at right angles on a plate are being discussed as a new approach to measure and locate the source of acoustic waves. Evolutionary novel signal processing algorithms and bio-inspired distributed sensor array systems are used on large structures and integrated aerospace vehicles for AE source localization and preliminary results are presented. These systems allow for a great reduction in the amount of data that needs to be processed and also reduce the chances of false alarms from ambient noises. It is envisioned that these biomimetic sensor arrays and signal processing techniques will be useful for both wireless and wired sensor arrays for real time health monitoring of large integrated aerospace vehicles and earth fixed civil structures. The sensor array architectures can also be used with other types of sensors and for other applications.

  15. Thin-Film Air-Mass-Flow Sensor of Improved Design Developed

    NASA Technical Reports Server (NTRS)

    Fralick, Gustave C.; Wrbanek, John D.; Hwang, Danny P.

    2003-01-01

    Researchers at the NASA Glenn Research Center have developed a new air-mass-flow sensor to solve the problems of existing mass flow sensor designs. NASA's design consists of thin-film resistors in a Wheatstone bridge arrangement. The resistors are fabricated on a thin, constant-thickness airfoil to minimize disturbance to the airflow being measured. The following photograph shows one of NASA s prototype sensors. In comparison to other air-mass-flow sensor designs, NASA s thin-film sensor is much more robust than hot wires, causes less airflow disturbance than pitot tubes, is more accurate than vane anemometers, and is much simpler to operate than thermocouple rakes. NASA s thin-film air-mass-flow sensor works by converting the temperature difference seen at each leg of the thin-film Wheatstone bridge into a mass-flow rate. The following figure shows a schematic of this sensor with air flowing around it. The sensor operates as follows: current is applied to the bridge, which increases its temperature. If there is no flow, all the arms are heated equally, the bridge remains in balance, and there is no signal. If there is flow, the air passing over the upstream legs of the bridge reduces the temperature of the upstream legs and that leads to reduced electrical resistance for those legs. After the air has picked up heat from the upstream legs, it continues and passes over the downstream legs of the bridge. The heated air raises the temperature of these legs, increasing their electrical resistance. The resistance difference between the upstream and downstream legs unbalances the bridge, causing a voltage difference that can be amplified and calibrated to the airflow rate. Separate sensors mounted on the airfoil measure the temperature of the airflow, which is used to complete the calculation for the mass of air passing by the sensor. A current application for air-mass-flow sensors is as part of the intake system for an internal combustion engine. A mass-flow sensor is

  16. Center of mass detection via an active pixel sensor

    NASA Technical Reports Server (NTRS)

    Yadid-Pecht, Orly (Inventor); Minch, Brad (Inventor); Pain, Bedabrara (Inventor); Fossum, Eric (Inventor)

    2006-01-01

    An imaging system for identifying the location of the center of mass (COM) in an image. In one aspect, an imaging system includes a plurality of photosensitive elements arranged in a matrix. A center of mass circuit coupled to the photosensitive elements includes a resistive network and a normalization circuit including at least one bipolar transistor. The center of mass circuit identifies a center of mass location in the matrix and includes: a row circuit, where the row circuit identifies a center of mass row value in each row of the matrix and identifies a row intensity for each row; a horizontal circuit, where the horizontal circuit identifies a center of mass horizontal value; and a vertical circuit, where the vertical circuit identifies a center of mass vertical value. The horizontal and vertical center of mass values indicate the coordinates of the center of mass location for the image.

  17. Center of mass detection via an active pixel sensor

    NASA Technical Reports Server (NTRS)

    Yadid-Pecht, Orly (Inventor); Minch, Brad (Inventor); Pain, Bedabrata (Inventor); Fossum, Eric (Inventor)

    2005-01-01

    An imaging system for identifying the location of the center of mass (COM) in an image. In one aspect, an imaging system includes a plurality of photosensitive elements arranged in a matrix. A center of mass circuit coupled to the photosensitive elements includes a resistive network and a normalization circuit including at least one bipolar transistor. The center of mass circuit identifies a center of mass location in the matrix and includes: a row circuit, where the row circuit identifies a center of mass row value in each row of the matrix and identifies a row intensity for each row; a horizontal circuit, where the horizontal circuit identifies a center of mass horizontal value; and a vertical circuit, where the vertical circuit identifies a center of mass vertical value. The horizontal and vertical center of mass values indicate the coordinates of the center of mass location for the image.

  18. Center of mass detection via an active pixel sensor

    NASA Technical Reports Server (NTRS)

    Yadid-Pecht, Orly (Inventor); Minch, Brad (Inventor); Pain, Bedabrata (Inventor); Fossum, Eric (Inventor)

    2002-01-01

    An imaging system for identifying the location of the center of mass (COM) in an image. In one aspect, an imaging system includes a plurality of photosensitive elements arranged in a matrix. A center of mass circuit coupled to the photosensitive elements includes a resistive network and a normalization circuit including at least one bipolar transistor. The center of mass circuit identifies a center of mass location in the matrix and includes: a row circuit, where the row circuit identifies a center of mass row value in each row of the matrix and identifies a row intensity for each row; a horizontal circuit, where the horizontal circuit identifies a center of mass horizontal value; and a vertical circuit, where the vertical circuit identifies a center of mass vertical value. The horizontal and vertical center of mass values indicate the coordinates of the center of mass location for the image.

  19. Effect of film thickness and viscoelasticity on separability of vapour classes by wavelet and principal component analyses of polymer-coated surface acoustic wave sensor transients

    NASA Astrophysics Data System (ADS)

    Singh, Prashant; Yadava, R. D. S.

    2011-02-01

    The transient response of a polymer-coated surface acoustic wave (SAW) vapour sensor depends on partitioning and diffusion of vapour species into the polymer in conjunction with its thickness and viscoelastic properties. The shapes of transient signals carry information about vapour identities due to specificity of the partition coefficient and the diffusion coefficient. The analysis of transient signals therefore offers a simpler approach for vapour identification in comparison to conventional electronic nose systems that employ a broadly selective sensor array. The transient response-based methods are however not developed to a similar level of maturity as their sensor array counterparts. The main reason for this is associated with complex signal generation kinetics and polymer viscoelasticity. The latter is independent of vapour identities (assuming low concentrations) but influences sensor response through nonlinear dependences on polymer thickness and viscoelastic coefficients. In this paper, we endeavour to find out whether viscoelasticity and its manifestation through thickness dependences could be turned into an advantage for transient-based vapour identification. Using an established SAW sensor model with additive noise we analyse sensor transients by wavelet decomposition and principal component analysis (PCA) for various combinations of polymer thickness, viscoelastic storage and loss moduli and noise level. We calculate vapour class separability measures defined on the basis of scatter matrices of principal components of wavelet coefficients to determine the discrimination ability of sensor transients for various combinations of film thickness and viscoelastic parameters. The simulation experiments are performed by considering a polyisobutylene-coated SAW oscillator sensor under exposure to seven volatile organic compounds (chloroform, chlorobenzene, o-dichlorobenzene, n-heptane, toluene, n-hexane and n-octane). The film thicknesses are varied from thin

  20. Coherent optical propagation and ultrahigh resolution mass sensor based on photonic molecules optomechanics

    NASA Astrophysics Data System (ADS)

    Chen, Hua-Jun; Chen, Chang-Zhao; Li, Yang; Fang, Xian-Wen; Tang, Xu-Dong

    2017-01-01

    We theoretically demonstrate the coherent optical propagation properties based on a photonic molecules optomechanics. With choosing a suitable detuning of the pump field from optomechanical cavity resonance, both the slow- and fast-light effect of the probe field appear in the system. The coupling strength of the two cavities play a key role, which affords a quantum channel and influences the width of the transparency window. Based on the photonic molecules optomechanical system, a high resolution mass sensor is also proposed. The mass of external nanoparticles deposited onto the cavity can be measured straightforward via tracking the mechanical resonance frequency shifts due to mass changes in the probe transmission spectrum. Compared with the single-cavity optomechanics mass sensors, the mass resolution is improved significantly due to the cavity-cavity coupling. The photonic molecules optomechanics provide a new platform for on-chip applications in quantum information processing and ultrahigh resolution sensor devices.

  1. Modeling, design, fabrication and characterization of a micro Coriolis mass flow sensor

    NASA Astrophysics Data System (ADS)

    Haneveld, J.; Lammerink, T. S. J.; de Boer, M. J.; Sanders, R. G. P.; Mehendale, A.; Lötters, J. C.; Dijkstra, M.; Wiegerink, R. J.

    2010-12-01

    This paper discusses the modeling, design and realization of micromachined Coriolis mass flow sensors. A lumped element model is used to analyze and predict the sensor performance. The model is used to design a sensor for a flow range of 0-1.2 g h-1 with a maximum pressure drop of 1 bar. The sensor was realized using semi-circular channels just beneath the surface of a silicon wafer. The channels have thin silicon nitride walls to minimize the channel mass with respect to the mass of the moving fluid. Special comb-shaped electrodes are integrated on the channels for capacitive readout of the extremely small Coriolis displacements. The comb-shaped electrode design eliminates the need for multiple metal layers and sacrificial layer etching methods. Furthermore, it prevents squeezed film damping due to a thin layer of air between the capacitor electrodes. As a result, the sensor operates at atmospheric pressure with a quality factor in the order of 40 and does not require vacuum packaging like other micro Coriolis flow sensors. Measurement results using water, ethanol, white gas and argon are presented, showing that the sensor measures true mass flow. The measurement error is currently in the order of 1% of the full scale of 1.2 g h-1.

  2. Multiplexing of fiber-optic acoustic sensors in a Michelson interferometer configuration.

    PubMed

    Sun, Changsen

    2003-06-15

    A new multiplexing method demonstrating the separation of two series of geometrically arranged fiber-optic distributed sensors in a Michelson interferometer (MI) configuration has been developed. This method can acquire data from two sensors, then propagate the data into one channel, and finally separate the data by determining their working point, which is essential for some remote measurements. The working point of one sensor was deflected from the normal MI by introduction of two reference arms. The deflection was extracted electrically and employed to label the sensor. Verification with commercial piezoelectric transducers proves the efficiency of the method.

  3. Conductometric Sensor for Soot Mass Flow Detection in Exhausts of Internal Combustion Engines.

    PubMed

    Feulner, Markus; Hagen, Gunter; Müller, Andreas; Schott, Andreas; Zöllner, Christian; Brüggemann, Dieter; Moos, Ralf

    2015-11-13

    Soot sensors are required for on-board diagnostics (OBD) of automotive diesel particulate filters (DPF) to detect filter failures. Widely used for this purpose are conductometric sensors, measuring an electrical current or resistance between two electrodes. Soot particles deposit on the electrodes, which leads to an increase in current or decrease in resistance. If installed upstream of a DPF, the "engine-out" soot emissions can also be determined directly by soot sensors. Sensors were characterized in diesel engine real exhausts under varying operation conditions and with two different kinds of diesel fuel. The sensor signal was correlated to the actual soot mass and particle number, measured with an SMPS. Sensor data and soot analytics (SMPS) agreed very well, an impressing linear correlation in a double logarithmic representation was found. This behavior was even independent of the used engine settings or of the biodiesel content.

  4. Conductometric Sensor for Soot Mass Flow Detection in Exhausts of Internal Combustion Engines

    PubMed Central

    Feulner, Markus; Hagen, Gunter; Müller, Andreas; Schott, Andreas; Zöllner, Christian; Brüggemann, Dieter; Moos, Ralf

    2015-01-01

    Soot sensors are required for on-board diagnostics (OBD) of automotive diesel particulate filters (DPF) to detect filter failures. Widely used for this purpose are conductometric sensors, measuring an electrical current or resistance between two electrodes. Soot particles deposit on the electrodes, which leads to an increase in current or decrease in resistance. If installed upstream of a DPF, the “engine-out” soot emissions can also be determined directly by soot sensors. Sensors were characterized in diesel engine real exhausts under varying operation conditions and with two different kinds of diesel fuel. The sensor signal was correlated to the actual soot mass and particle number, measured with an SMPS. Sensor data and soot analytics (SMPS) agreed very well, an impressing linear correlation in a double logarithmic representation was found. This behavior was even independent of the used engine settings or of the biodiesel content. PMID:26580621

  5. A new strategy toward Internet of Things: structural health monitoring using a combined fiber optic and acoustic emission wireless sensor platform

    NASA Astrophysics Data System (ADS)

    Nguyen, A. D.; Page, C.; Wilson, C. L.

    2016-04-01

    This paper investigates a new low-power structural health monitoring (SHM) strategy where fiber Bragg grating (FBG) rosettes can be used to continuously monitor for changes in a host structure's principal strain direction, suggesting damage and thus enabling the immediate triggering of a higher power acoustic emissions (AE) sensor to provide for better characterization of the damage. Unlike traditional "always on" AE platforms, this strategy has the potential for low power, while the wireless communication between different sensor types supports the Internet of Things (IoT) approach. A combination of fiber-optic sensor rosettes for strain monitoring and a fiber-optic sensor for acoustic emissions monitoring was attached to a sample and used to monitor crack initiation. The results suggest that passive principal strain direction monitoring could be used as a damage initiation trigger for other active sensing elements such as acoustic emissions. In future work, additional AE sensors can be added to provide for damage location; and a strategy where these sensors can be powered on periodically to further establish reliability while preserving an energy efficient scheme can be incorporated.

  6. Acoustic sensor for real-time control for the inductive heating process

    DOEpatents

    Kelley, John Bruce; Lu, Wei-Yang; Zutavern, Fred J.

    2003-09-30

    Disclosed is a system and method for providing closed-loop control of the heating of a workpiece by an induction heating machine, including generating an acoustic wave in the workpiece with a pulsed laser; optically measuring displacements of the surface of the workpiece in response to the acoustic wave; calculating a sub-surface material property by analyzing the measured surface displacements; creating an error signal by comparing an attribute of the calculated sub-surface material properties with a desired attribute; and reducing the error signal below an acceptable limit by adjusting, in real-time, as often as necessary, the operation of the inductive heating machine.

  7. Using acoustic sensors to improve the efficiency of the forest value chain in Canada: a case study with laminated veneer lumber.

    PubMed

    Achim, Alexis; Paradis, Normand; Carter, Peter; Hernández, Roger E

    2011-01-01

    Engineered wood products for structural use must meet minimum strength and stiffness criteria. This represents a major challenge for the industry as the mechanical properties of the wood resource are inherently variable. We report on a case study that was conducted in a laminated veneer lumber (LVL) mill in order to test the potential of an acoustic sensor to predict structural properties of the wood resource prior to processing. A population of 266 recently harvested aspen logs were segregated into three sub-populations based on measurements of longitudinal acoustic speed in wood using a hand tool equipped with a resonance-based acoustic sensor. Each of the three sub-populations were peeled into veneer sheets and graded for stiffness with an ultrasonic device. The average ultrasonic propagation time (UPT) of each subpopulation was 418, 440 and 453 microseconds for the green, blue, and red populations, respectively. This resulted in contrasting proportions of structural veneer grades, indicating that the efficiency of the forest value chain could be improved using acoustic sensors. A linear regression analysis also showed that the dynamic modulus of elasticity (MOE) of LVL was strongly related to static MOE (R(2) = 0.83), which suggests that acoustic tools may be used for quality control during the production process.

  8. Using Acoustic Sensors to Improve the Efficiency of the Forest Value Chain in Canada: A Case Study with Laminated Veneer Lumber

    PubMed Central

    Achim, Alexis; Paradis, Normand; Carter, Peter; Hernández, Roger E.

    2011-01-01

    Engineered wood products for structural use must meet minimum strength and stiffness criteria. This represents a major challenge for the industry as the mechanical properties of the wood resource are inherently variable. We report on a case study that was conducted in a laminated veneer lumber (LVL) mill in order to test the potential of an acoustic sensor to predict structural properties of the wood resource prior to processing. A population of 266 recently harvested aspen logs were segregated into three sub-populations based on measurements of longitudinal acoustic speed in wood using a hand tool equipped with a resonance-based acoustic sensor. Each of the three sub-populations were peeled into veneer sheets and graded for stiffness with an ultrasonic device. The average ultrasonic propagation time (UPT) of each subpopulation was 418, 440 and 453 microseconds for the green, blue, and red populations, respectively. This resulted in contrasting proportions of structural veneer grades, indicating that the efficiency of the forest value chain could be improved using acoustic sensors. A linear regression analysis also showed that the dynamic modulus of elasticity (MOE) of LVL was strongly related to static MOE (R2 = 0.83), which suggests that acoustic tools may be used for quality control during the production process. PMID:22163922

  9. Aluminum nitride thin film based acoustic wave sensors for biosensing applications

    NASA Astrophysics Data System (ADS)

    Xu, Jianzeng

    In recent years, SAW devices have drawn enormous interest from the analytical assay and sensing business, especially in the biosensing area where highly sensitive, cost efficient and miniaturized sensors are in urgent needs. This dissertation focuses on the development of AIN thin film based SAW devices suitable for biosensing applications. AIN thin films have been synthesized on different orientations of sapphire substrates by a plasma source molecular beam epitaxy system. Surface and structural characterization techniques have been applied to investigate the film quality and the results show that high quality c-plane AIN was epitaxially grown on both c-plane and a-plane sapphire substrates. Complete process flows have been developed for the fabrication of SAW delay line and resonator devices. Important electrical parameters such as the insertion loss, bandwidth, and impedance have been measured to assist the design optimization and derivation the phase velocity, electromechanical coupling coefficient, and temperature coefficient of frequency. On both c-plane and a-plane sapphire substrates, the SAW phase velocities (˜5700 m/s) and electromechanical coupling coefficients (˜0.3%) have been thoroughly mapped out with respect to the propagation direction and film thickness to wavelength ratio. The data are of practical importance for designing AIN-based SAW devices. A higher velocity (>6000 m/s) shear horizontal SAW mode has been discovered only at isolated propagating directions. This mode is especially suitable for aqueous biosensing due to its weak energy coupling to liquid. Much stronger response of the SH-SAW mode has been detected on the c-plane AIN on a-plane sapphire structure than on the c-plane AIN on c-plane sapphire structure, which could be attributed to large anisotropy in a-plane sapphire substrate. Linear frequency-temperature relationship has also been observed for both modes. We further quantify the mass sensitivity of the SAW and SH-SAW by

  10. Thermal Acoustic Sensor for High Pulse Energy X-ray FEL Beams

    SciTech Connect

    Smith, T.J.; Frisch, J.C.; Kraft, E.M.; Loos, J.; Bentsen, G.S.; /Rochester U.

    2011-12-13

    The pulse energy density of X-ray FELs will saturate or destroy conventional X-ray diagnostics, and the use of large beam attenuation will result in a beam that is dominated by harmonics. We present preliminary results at the LCLS from a pulse energy detector based on the thermal acoustic effect. In this type of detector an X-ray resistant material (boron carbide in this system) intercepts the beam. The pulse heating of the target material produces an acoustic pulse that can be detected with high frequency microphones to produce a signal that is linear in the absorbed energy. The thermal acoustic detector is designed to provide first- and second-order calorimetric measurement of X-ray FEL pulse energy. The first-order calorimetry is a direct temperature measurement of a target designed to absorb all or most of the FEL pulse power with minimal heat leak. The second-order measurement detects the vibration caused by the rapid thermoelastic expansion of the target material each time it absorbs a photon pulse. Both the temperature change and the amplitude of the acoustic signal are directly related to the photon pulse energy.

  11. Monolithic mass sensor fabricated using a conventional technology with attogram resolution in air conditions

    NASA Astrophysics Data System (ADS)

    Verd, J.; Uranga, A.; Abadal, G.; Teva, J.; Torres, F.; Pérez-Murano, F.; Fraxedas, J.; Esteve, J.; Barniol, N.

    2007-07-01

    Monolithic mass sensors for ultrasensitive mass detection in air conditions have been fabricated using a conventional 0.35μm complementary metal-oxide-semiconductor (CMOS) process. The mass sensors are based on electrostatically excited submicrometer scale cantilevers integrated with CMOS electronics. The devices have been calibrated obtaining an experimental sensitivity of 6×10-11g/cm2Hz equivalent to 0.9ag/Hz for locally deposited mass. Results from time-resolved mass measurements are also presented. An evaluation of the mass resolution have been performed obtaining a value of 2.4×10-17g in air conditions, resulting in an improvement of these devices from previous works in terms of sensitivity, resolution, and fabrication process complexity.

  12. Laser-induced acoustic desorption/atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Gao, Jinshan; Borton, David J; Owen, Benjamin C; Jin, Zhicheng; Hurt, Matt; Amundson, Lucas M; Madden, Jeremy T; Qian, Kuangnan; Kenttämaa, Hilkka I

    2011-03-01

    Laser-induced acoustic desorption (LIAD) was successfully coupled to a conventional atmospheric pressure chemical ionization (APCI) source in a commercial linear quadrupole ion trap mass spectrometer (LQIT). Model compounds representing a wide variety of different types, including basic nitrogen and oxygen compounds, aromatic and aliphatic compounds, as well as unsaturated and saturated hydrocarbons, were tested separately and as a mixture. These model compounds were successfully evaporated into the gas phase by using LIAD and then ionized by using APCI with different reagents. From the four APCI reagent systems tested, neat carbon disulfide provided the best results. The mixture of methanol and water produced primarily protonated molecules, as expected. However, only the most basic compounds yielded ions under these conditions. In sharp contrast, using APCI with either neat benzene or neat carbon disulfide as the reagent resulted in the ionization of all the analytes studied to predominantly yield stable molecular ions. Benzene yielded a larger fraction of protonated molecules than carbon disulfide, which is a disadvantage. A similar but minor amount of fragmentation was observed for these two reagents. When the experiment was performed without a liquid reagent (nitrogen gas was the reagent), more fragmentation was observed. Analysis of a known mixture as well as a petroleum cut was also carried out. In summary, the new experiment presented here allows the evaporation of thermally labile compounds, both polar and nonpolar, without dissociation or aggregation, and their ionization to predominantly form stable molecular ions.

  13. Laser-Induced Acoustic Desorption/Atmospheric Pressure Chemical Ionization Mass Spectrometry

    PubMed Central

    Gao, Jinshan; Borton, David J.; Owen, Benjamin C.; Jin, Zhicheng; Hurt, Matt; Amundson, Lucas M.; Madden, Jeremy T.; Qian, Kuangnan; Kenttämaa, Hilkka I.

    2010-01-01

    Laser-induced acoustic desorption (LIAD) was successfully coupled to a conventional atmospheric pressure chemical ionization (APCI) source in a linear quadrupole ion trap mass spectrometer (LQIT). Model compounds representing a wide variety of different types, including basic nitrogen and oxygen compounds, aromatic and aliphatic compounds, as well as unsaturated and saturated hydrocarbons, were tested separately and as a mixture. These model compounds were successfully evaporated into the gas phase by using LIAD and then ionized by using APCI with different reagents. Four APCI reagent systems were tested: the traditionally used mixture of methanol and water, neat benzene, neat carbon disulfide, and nitrogen gas (no liquid reagent). The mixture of methanol and water produced primarily protonated molecules, as expected. However, only the most basic compounds yielded ions under these conditions. In sharp contrast, using APCI with either neat benzene or neat carbon disulfide as the reagent resulted in the ionization of all the analytes studied to predominantly yield stable molecular ions. Benzene yielded a larger fraction of protonated molecules than carbon disulfide, which is a disadvantage. A similar amount of fragmentation was observed for these reagents. When the experiment was performed without a liquid reagent(nitrogen gas was the reagent), more fragmentation was observed. Analysis of a known mixture as well as a petroleum cut was also carried out. In summary, the new experiment presented here allows the evaporation of thermally labile compounds, both polar and nonpolar, without dissociation or aggregation, and their ionization to form stable molecular ions. PMID:21472571

  14. Multi-event waveform-retrieved distributed optical fiber acoustic sensor using dual-pulse heterodyne phase-sensitive OTDR.

    PubMed

    He, Xiangge; Xie, Shangran; Liu, Fei; Cao, Shan; Gu, Lijuan; Zheng, Xiaoping; Zhang, Min

    2017-02-01

    We demonstrate a novel type of distributed optical fiber acoustic sensor, with the ability to detect and retrieve actual temporal waveforms of multiple vibration events that occur simultaneously at different positions along the fiber. The system is realized via a dual-pulse phase-sensitive optical time-domain reflectometry, and the actual waveform is retrieved by heterodyne phase demodulation. Experimental results show that the system has a background noise level as low as 8.91×10-4  rad/√Hz with a demodulation signal-to-noise ratio of 49.17 dB at 1 kHz, and can achieve a dynamic range of ∼60  dB at 1 kHz (0.1 to 104 rad) for phase demodulation, as well as a detection frequency range from 20 Hz to 25 kHz.

  15. Primate Drum Kit: A System for Studying Acoustic Pattern Production by Non-Human Primates Using Acceleration and Strain Sensors

    PubMed Central

    Ravignani, Andrea; Olivera, Vicente Matellán; Gingras, Bruno; Hofer, Riccardo; Hernández, Carlos Rodríguez; Sonnweber, Ruth-Sophie; Fitch, W. Tecumseh

    2013-01-01

    The possibility of achieving experimentally controlled, non-vocal acoustic production in non-human primates is a key step to enable the testing of a number of hypotheses on primate behavior and cognition. However, no device or solution is currently available, with the use of sensors in non-human animals being almost exclusively devoted to applications in food industry and animal surveillance. Specifically, no device exists which simultaneously allows: (i) spontaneous production of sound or music by non-human animals via object manipulation, (ii) systematical recording of data sensed from these movements, (iii) the possibility to alter the acoustic feedback properties of the object using remote control. We present two prototypes we developed for application with chimpanzees (Pan troglodytes) which, while fulfilling the aforementioned requirements, allow to arbitrarily associate sounds to physical object movements. The prototypes differ in sensing technology, costs, intended use and construction requirements. One prototype uses four piezoelectric elements embedded between layers of Plexiglas and foam. Strain data is sent to a computer running Python through an Arduino board. A second prototype consists in a modified Wii Remote contained in a gum toy. Acceleration data is sent via Bluetooth to a computer running Max/MSP. We successfully pilot tested the first device with a group of chimpanzees. We foresee using these devices for a range of cognitive experiments. PMID:23912427

  16. Canonical Acoustics and Its Application to Surface Acoustic Wave on Acoustic Metamaterials

    NASA Astrophysics Data System (ADS)

    Shen, Jian Qi

    2016-08-01

    In a conventional formalism of acoustics, acoustic pressure p and velocity field u are used for characterizing acoustic waves propagating inside elastic/acoustic materials. We shall treat some fundamental problems relevant to acoustic wave propagation alternatively by using canonical acoustics (a more concise and compact formalism of acoustic dynamics), in which an acoustic scalar potential and an acoustic vector potential (Φ ,V), instead of the conventional acoustic field quantities such as acoustic pressure and velocity field (p,u) for characterizing acoustic waves, have been defined as the fundamental variables. The canonical formalism of the acoustic energy-momentum tensor is derived in terms of the acoustic potentials. Both the acoustic Hamiltonian density and the acoustic Lagrangian density have been defined, and based on this formulation, the acoustic wave quantization in a fluid is also developed. Such a formalism of acoustic potentials is employed to the problem of negative-mass-density assisted surface acoustic wave that is a highly localized surface bound state (an eigenstate of the acoustic wave equations). Since such a surface acoustic wave can be strongly confined to an interface between an acoustic metamaterial (e.g., fluid-solid composite structures with a negative dynamical mass density) and an ordinary material (with a positive mass density), it will give rise to an effect of acoustic field enhancement on the acoustic interface, and would have potential applications in acoustic device design for acoustic wave control.

  17. On the acoustic filtering of the pipe and sensor in a buried plastic water pipe and its effect on leak detection: an experimental investigation.

    PubMed

    Almeida, Fabrício; Brennan, Michael; Joseph, Phillip; Whitfield, Stuart; Dray, Simon; Paschoalini, Amarildo

    2014-03-20

    Acoustic techniques have been used for many years to find and locate leaks in buried water distribution systems. Hydrophones and accelerometers are typically used as sensors. Although geophones could be used as well, they are not generally used for leak detection. A simple acoustic model of the pipe and the sensors has been proposed previously by some of the authors of this paper, and their model was used to explain some of the features observed in measurements. However, simultaneous measurements of a leak using all three sensor-types in controlled conditions for plastic pipes has not been reported to-date and hence they have not yet been compared directly. This paper fills that gap in knowledge. A set of measurements was made on a bespoke buried plastic water distribution pipe test rig to validate the previously reported analytical model. There is qualitative agreement between the experimental results and the model predictions in terms of the differing filtering properties of the pipe-sensor systems. A quality measure for the data is also presented, which is the ratio of the bandwidth over which the analysis is carried out divided by the centre frequency of this bandwidth. Based on this metric, the accelerometer was found to be the best sensor to use for the test rig described in this paper. However, for a system in which the distance between the sensors is large or the attenuation factor of the system is high, then it would be advantageous to use hydrophones, even though they are invasive sensors.

  18. Position and mass determination of multiple particles using cantilever based mass sensors

    SciTech Connect

    Dohn, Soeren; Schmid, Silvan; Boisen, Anja; Amiot, Fabien

    2010-07-26

    Resonant microcantilevers are highly sensitive to added masses and have the potential to be used as mass-spectrometers. However, making the detection of individual added masses quantitative requires the position determination for each added mass. We derive expressions relating the position and mass of several added particles to the resonant frequencies of a cantilever, and an identification procedure valid for particles with different masses is proposed. The identification procedure is tested by calculating positions and mass of multiple microparticles with similar mass positioned on individual microcantilevers. Excellent agreement is observed between calculated and measured positions and calculated and theoretical masses.

  19. Cheap DECAF: Density Estimation for Cetaceans from Acoustic Fixed Sensors Using Separate, Non-Linked Devices

    DTIC Science & Technology

    2014-06-29

    Andrews have begun a new research effort with Penn State University, "Large Scale Density Estimation of Blue and Fin Whales ", funded by ONR. This...research groups that hold acoustic tag data for blue and fin whales and assist them in estimating cue rates that could be used in appropriate density...ABSTRACT Recordings of fin whales (Balaenoptera physalus) from a sparse array of Ocean Bottom Seismometers (OBSs) have been used to (1) demonstrate the use

  20. System for Multiplexing Acoustic Emission (AE) Instrumentation

    NASA Technical Reports Server (NTRS)

    Prosser, William H. (Inventor); Perey, Daniel F. (Inventor); Gorman, Michael R. (Inventor); Scales, Edgar F. (Inventor)

    2003-01-01

    An acoustic monitoring device has at least two acoustic sensors with a triggering mechanism and a multiplexing circuit. After the occurrence of a triggering event at a sensor, the multiplexing circuit allows a recording component to record acoustic emissions at adjacent sensors. The acoustic monitoring device is attached to a solid medium to detect the occurrence of damage.

  1. Fiber optic liquid mass flow sensor and method

    NASA Technical Reports Server (NTRS)

    Korman, Valentin (Inventor); Gregory, Don Allen (Inventor); Wiley, John T. (Inventor); Pedersen, Kevin W. (Inventor)

    2010-01-01

    A method and apparatus are provided for sensing the mass flow rate of a fluid flowing through a pipe. A light beam containing plural individual wavelengths is projected from one side of the pipe across the width of the pipe so as to pass through the fluid under test. Fiber optic couplers located at least two positions on the opposite side of the pipe are used to detect the light beam. A determination is then made of the relative strengths of the light beam for each wavelength at the at least two positions and based at least in part on these relative strengths, the mass flow rate of the fluid is determined.

  2. Gas sensing with surface acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Martin, S. J.; Schweizer, K. S.; Ricco, A. J.; Zipperian, T. E.

    1985-03-01

    The use of a ZnO-on-Si surface acoustic wave (SAW) resonator as a gas sensor is discussed. In particular, the sensitivity of the device to organic vapors is examined. The planar nature of the SAW device, in which the acoustic energy is confined to within roughly one acoustic wavelength of the surface, makes the device extremely sensitive to surface perturbations. This characteristic has been exploited in the construction of SAW gas sensors in which the surface wave propagation characteristics are altered by species adsorbed from the ambient gas. The porous nature of the sputtered ZnO film, in conjunction with the microbalance capability of the SAW device, gives the sensor the ability to distinguish molecules on the basis of both size and mass.

  3. Anomalous wave propagation in a one-dimensional acoustic metamaterial having simultaneously negative mass density and Young's modulus.

    PubMed

    Huang, H H; Sun, C T

    2012-10-01

    A mechanical model representing an acoustic metamaterial that exhibits simultaneously negative mass density and negative Young's modulus was proposed. Wave propagation was studied in the frequency range of double negativity. In view of positive energy flow, it was found that the phase velocity in this range is negative. This phenomenon was also observed using transient wave propagation finite-element analyses of a transient sinusoidal wave and a transient wave packet. In contrast to wave propagation in the region of positive mass and modulus, the peculiar backward wave motion in the region of double negativity was clearly displayed.

  4. Modeling and Simulation of a Spinning Spherical Test Mass for Modular Gravitational Reference Sensor

    NASA Astrophysics Data System (ADS)

    Sun, Ke-Xun; Conklin, John; Allen, Graham; Buchman, Sasha; Byer, Robert; Debra, Dan

    In a drag-free spacecraft, the spacecraft computer uses input from displacement sensors to fly at a constant distance from a free- floating test mass inside the spcaecraft. Optical sensors offer higher resolution and zero stiffness compared to capacitive sensors, but the small spot size makes them much more sensitive to test mass surface irregularities. Except for these residual geometric irregularities, the sphere is orientation invariant. Consequently, with a spherical test mass, we can eliminate electrostatic suspension for orientation control, which can cause unwanted forcing of the test mass. Spinning a sphere spectrally shifts the surface irregularities as well as the mass center offset from the geometric center out of the desired sensing band. Given that the outof-roundness and mass center offset of a sphere can be 105 larger than the desired resolution, special care must be taken to avoid aliasing spin frequency information into the science band. An analytical model for the output of a drag-free sensor using a spherical test mass including all first order contributions is developed. With this model, we evaluate systematic errors in the mass center measurement due to geometric variations which place requirements on spacecraft attitude and test mass dynamics. We also present a fast and reliable algorithm for recovering the mass center location and spin frequency of the test mass, in real-time, to picometer level from the sensor data. This algorithm involves fitting and removing the spin harmonics from the sensor output and uses the phase of the fitted harmonics to track the test mass spin frequency in real-time. A numerical simulation is developed to compared this algorithm to other possible data processing methods including a straight-forward tuned digital filter and a surface mapping algorithm. The computational complexity of each algorithm is analyzed since in there is limited CPU power on a satellite, and there is insufficient bandwidth for transmitting

  5. Dynamic Modeling Accuracy Dependence on Errors in Sensor Measurements, Mass Properties, and Aircraft Geometry

    NASA Technical Reports Server (NTRS)

    Grauer, Jared A.; Morelli, Eugene A.

    2013-01-01

    A nonlinear simulation of the NASA Generic Transport Model was used to investigate the effects of errors in sensor measurements, mass properties, and aircraft geometry on the accuracy of dynamic models identified from flight data. Measurements from a typical system identification maneuver were systematically and progressively deteriorated and then used to estimate stability and control derivatives within a Monte Carlo analysis. Based on the results, recommendations were provided for maximum allowable errors in sensor measurements, mass properties, and aircraft geometry to achieve desired levels of dynamic modeling accuracy. Results using other flight conditions, parameter estimation methods, and a full-scale F-16 nonlinear aircraft simulation were compared with these recommendations.

  6. Acoustic sensor engineering evaluation test report. [microphones for monitoring inside the space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Phillips, E. L., Jr.; Bronson, R. D.

    1976-01-01

    Two types of one-inch diameter sound pressure level sensors, which are candidates for monitoring ambient noise in the shuttle orbiter crew compartment during rest periods, were exposed to temperature, passive humidity, and vibration. One unexposed sensor of each type served as a reference unit. Except for the humidity exposures, each of the three capacitive microphones was individually tested in sequence with the essential voltage power supply and preamplifier. One unit exibited anomalous characteristics after the humidity exposure but returned to normal after being dried in an oven at 115 deg for two hours. Except for the humidity exposures, each of the three piezoelectric microphones was individually tested with a laboratory type amplifier. Two apparent failures occurred during these tests. The diaphragm on one was found ruptured after the fourth cycle of the humidity test. A second sensor showed an anomaly after the random vibration tests at which time its sensitivity was consistent at about one-half its former value.

  7. Quantitative measurement of in-plane acoustic field components using surface-mounted fiber sensors

    NASA Technical Reports Server (NTRS)

    Claus, Richard O.; Dhawan, Rajat R.; Gunther, Michael F.; Murphy, Kent A.

    1993-01-01

    Extrinsic Fabry-Perot interferometric sensors have been used to obtain calibrated, quantitative measurements of the in-plane displacement components associated with the propagation of ultrasonic elastic stress waves on the surfaces of solids. The frequency response of the sensor is determined by the internal spacing between the two reflecting fiber endface surfaces which form the Fabry-Perot cavity, a distance which is easily controlled during fabrication. With knowledge of the material properties of the solid, the out-of-plane displacement component of the wave may also be determined, giving full field data.

  8. Monitoring of temperature fatigue failure mechanism for polyvinyl alcohol fiber concrete using acoustic emission sensors.

    PubMed

    Li, Dongsheng; Cao, Hai

    2012-01-01

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

  9. Oscillating bubble as a sensor of low frequency electro-acoustic signals in electrolytes.

    PubMed

    Tankovsky, N; Baerner, K; Barey, Dooa Abdel

    2006-08-16

    Small air-bubble deformations, caused by electro-acoustic signals generated in electrolytic solutions have been detected by angle-modulation of a refracted He-Ne laser beam. The observed electromechanical resonance at low frequency, below 100 Hz, has proved to be directly related to the oscillations of characteristic ion-doped water structures when driven by an external electric field. The presence of structure-breaking or structure-making ions modifies the water structure, which varies the mechanical losses of the oscillating system and can be registered as changes in the width of the observed resonance curves.

  10. Localization of CO2 Leakage from a Circular Hole on a Flat-Surface Structure Using a Circular Acoustic Emission Sensor Array

    PubMed Central

    Cui, Xiwang; Yan, Yong; Guo, Miao; Han, Xiaojuan; Hu, Yonghui

    2016-01-01

    Leak localization is essential for the safety and maintenance of storage vessels. This study proposes a novel circular acoustic emission sensor array to realize the continuous CO2 leak localization from a circular hole on the surface of a large storage vessel in a carbon capture and storage system. Advantages of the proposed array are analyzed and compared with the common sparse arrays. Experiments were carried out on a laboratory-scale stainless steel plate and leak signals were obtained from a circular hole in the center of this flat-surface structure. In order to reduce the influence of the ambient noise and dispersion of the acoustic wave on the localization accuracy, ensemble empirical mode decomposition is deployed to extract the useful leak signal. The time differences between the signals from the adjacent sensors in the array are calculated through correlation signal processing before estimating the corresponding distance differences between the sensors. A hyperbolic positioning algorithm is used to identify the location of the circular leak hole. Results show that the circular sensor array has very good directivity toward the circular leak hole. Furthermore, an optimized method is proposed by changing the position of the circular sensor array on the flat-surface structure or adding another circular sensor array to identify the direction of the circular leak hole. Experiential results obtained on a 100 cm × 100 cm stainless steel plate demonstrate that the full-scale error in the leak localization is within 0.6%. PMID:27869765

  11. The effects of pressure sensor acoustics on airdata derived from a High-angle-of-attack Flush Airdata Sensing (HI-FADS) system

    NASA Technical Reports Server (NTRS)

    Whitmore, Stephen A.; Moes, Timothy R.

    1991-01-01

    The accuracy of a nonintrusive high angle-of-attack flush airdata sensing (HI-FADS) system was verified for quasi-steady flight conditions up to 55 deg angle of attack during the F-18 High Alpha Research Vehicle (HARV) Program. The system is a matrix of nine pressure ports arranged in annular rings on the aircraft nose. The complete airdata set is estimated using nonlinear regression. Satisfactory frequency response was verified to the system Nyquist frequency (12.5 Hz). The effects of acoustical distortions within the individual pressure sensors of the nonintrusive pressure matrix on overall system performance are addressed. To quantify these effects, a frequency-response model describing the dynamics of acoustical distortion is developed and simple design criteria are derived. The model adjusts measured HI-FADS pressure data for the acoustical distortion and quantifies the effects of internal sensor geometries on system performance. Analysis results indicate that sensor frequency response characteristics very greatly with altitude, thus it is difficult to select satisfactory sensor geometry for all altitudes. The solution used presample filtering to eliminate resonance effects, and short pneumatic tubing sections to reduce lag effects. Without presample signal conditioning the system designer must use the pneumatic transmission line to attenuate the resonances and accept the resulting altitude variability.

  12. Coupling Laser Diode Thermal Desorption with Acoustic Sample Deposition to Improve Throughput of Mass Spectrometry-Based Screening.

    PubMed

    Haarhoff, Zuzana; Wagner, Andrew; Picard, Pierre; Drexler, Dieter M; Zvyaga, Tatyana; Shou, Wilson

    2016-02-01

    The move toward label-free screening in drug discovery has increased the demand for mass spectrometry (MS)-based analysis. Here we investigated the approach of coupling acoustic sample deposition (ASD) with laser diode thermal desorption (LDTD)-tandem mass spectrometry (MS/MS). We assessed its use in a cytochrome P450 (CYP) inhibition assay, where a decrease in metabolite formation signifies CYP inhibition. Metabolite levels for 3 CYP isoforms were measured as CYP3A4-1'-OH-midazolam, CYP2D6-dextrorphan, and CYP2C9-4'-OH-diclofenac. After incubation, samples (100 nL) were acoustically deposited onto a stainless steel 384-LazWell plate, then desorbed by an infrared laser directly from the plate surface into the gas phase, ionized by atmospheric pressure chemical ionization (APCI), and analyzed by MS/MS. Using this method, we achieved a sample analysis speed of 2.14 s/well, with bioanalytical performance comparable to the current online solid-phase extraction (SPE)-based MS method. An even faster readout speed was achieved when postreaction sample multiplexing was applied, where three reaction samples, one for each CYP, were transferred into the same well of the LazWell plate. In summary, LDTD coupled with acoustic sample deposition and multiplexing significantly decreased analysis time to 0.7 s/sample, making this MS-based approach feasible to support high-throughput screening (HTS) assays.

  13. Toward a Micro-Scale Acoustic Direction-Finding Sensor with Integrated Electronic Readout

    DTIC Science & Technology

    2013-06-01

    1998. [4] A. C. Mason , M. L. Oshinsky, and R. R. Hoy, “Hyperacute directional hearing in a mi- croscale auditory system,” Nature, vol. 410, pp. 686...mechanical (MEMS) sound sensor,” Master’s thesis, Naval Postgraduate School, 2012. [35] J. D. Roth , “Integration of a high sensitivity MEMS directional

  14. On the Mutual Information of Multi-hop Acoustic Sensors Network in Underwater Wireless Communication

    DTIC Science & Technology

    2014-05-01

    experimentally measured in underwater .................................................. 33 Figure 20. Matlab simulation Set Up for multi-hop...processing. Also, we have extensively used the Matlab programming in system design and simulation of sensors placement to maximize the data rate, mutual...simulations. Bit error rate testing with Matlab is very simple, but does require some prerequisite knowledge. BER testing requires a transmitter, a receiver

  15. Monitoring and failure analysis of corroded bridge cables under fatigue loading using acoustic emission sensors.

    PubMed

    Li, Dongsheng; Ou, Jinping; Lan, Chengming; Li, Hui

    2012-01-01

    Cables play an important role in cable-stayed systems, but are vulnerable to corrosion and fatigue damage. There is a dearth of studies on the fatigue damage evolution of corroded cable. In the present study, the acoustic emission (AE) technology is adopted to monitor the fatigue damage evolution process. First, the relationship between stress and strain is determined through a tensile test for corroded and non-corroded steel wires. Results show that the mechanical performance of corroded cables is changed considerably. The AE characteristic parameters for fatigue damage are then established. AE energy cumulative parameters can accurately describe the fatigue damage evolution of corroded cables. The failure modes in each phase as well as the type of acoustic emission source are determined based on the results of scanning electron microscopy. The waveform characteristics, damage types, and frequency distribution of the corroded cable at different damage phases are collected. Finally, the number of broken wires and breakage time of the cables are determined according to the variation in the margin index.

  16. Monitoring and Failure Analysis of Corroded Bridge Cables under Fatigue Loading Using Acoustic Emission Sensors

    PubMed Central

    Li, Dongsheng; Ou, Jinping; Lan, Chengming; Li, Hui

    2012-01-01

    Cables play an important role in cable-stayed systems, but are vulnerable to corrosion and fatigue damage. There is a dearth of studies on the fatigue damage evolution of corroded cable. In the present study, the acoustic emission (AE) technology is adopted to monitor the fatigue damage evolution process. First, the relationship between stress and strain is determined through a tensile test for corroded and non-corroded steel wires. Results show that the mechanical performance of corroded cables is changed considerably. The AE characteristic parameters for fatigue damage are then established. AE energy cumulative parameters can accurately describe the fatigue damage evolution of corroded cables. The failure modes in each phase as well as the type of acoustic emission source are determined based on the results of scanning electron microscopy. The waveform characteristics, damage types, and frequency distribution of the corroded cable at different damage phases are collected. Finally, the number of broken wires and breakage time of the cables are determined according to the variation in the margin index. PMID:22666009

  17. Integration of acoustic and light sensors for marine bio-mining

    NASA Astrophysics Data System (ADS)

    Wiegand, Gordon

    2016-05-01

    Maximum diversity of life exists within the estuaries and coral reefs of the Globe. The absence of vertebrate and other land dwelling adaptations has resulted in an enormous range of complexity among invertebrates and their symbiotic biome resulting in the generation of compounds finding uses in anti-tumor and antibiotic applications. It has been widely reported that the greatest factor limiting progress in characterizing and processing new therapeutics derived from invertebrates is the lack of adequate original material. Symbiotic bacteria within specific tunicates often synthesize antitumor compounds as secondary metabolites. We describe a 3-stage protocol that utilizes acoustic and photonic analysis of large areas of marine ecosystem and life forms. We refer to this as Estuary Assessment System (EAS), which includes a multi-frequency acoustic transducer/sensing instrument mounted on our research vessel. This generates a topological map of surveyed tracks of marine locations known to be habitats of useful actinobacteria laden invertebrates. Photonic devices are used to generate image and pulse data leading to location, identification and isolation of tunicates and actinobacteria.

  18. Relative activity of cholesterol in OPPC/cholesterol/sphingomyelin mixtures measured with an acoustic sensor.

    PubMed

    Melzak, Kathryn A; Gizeli, Electra

    2009-03-01

    Acoustic devices are sensitive to the mole fraction of cholesterol present in liposomes adsorbed to the device surface as a result of the different mechanical properties of the liposomes. This fact was exploited to develop an acoustic assay to determine the relative affinity of cholesterol for different lipid mixtures. In the assay described here, the initial rate of beta-cyclodextrin-induced removal of cholesterol was measured for liposomes having a range of compositions. The initial rate of cholesterol removal was found to be directly proportional to the concentration of beta-cyclodextrin (betaCD) present over the range of 0-7.5 mg/ml (0-6.6 mM), consistent with other assays measuring the betaCD-accelerated transfer of cholesterol between liposomes. The affinity of cholesterol for 1-oleoyl-2-palmitoyl-sn-glycero-3-phosphocholine (OPPC) liposomes with a sphingomyelin mole fraction, chi(SPM), of 0.2 was found to be 1.4x higher than that for pure OPPC liposomes. For liposomes composed only of OPPC and cholesterol in varying ratios, the initial rate of cholesterol removal was determined as a function of cholesterol mole fraction (chi(C)). The initial rate of removal showed an increase at chi(C) = 0.13, consistent with phase diagrams showing the start of liquid ordered domain formation, but no such increase at chi(C) = 0.25, in contrast to the predictions of the umbrella model for OPPC/cholesterol interactions.

  19. A microcantilever-based silver ion sensor using DNA-functionalized gold nanoparticles as mass amplifier.

    PubMed

    You, Juneseok; Song, Yeongjin; Park, Chanho; Jang, Kuewhan; Na, Sungsoo

    2017-04-13

    Silver ions have been used to sterilize many products, however, it has recently been demonstrated that silver ions can be toxic. This toxicity has been researched over many years with the lethal concentration at 10 μM. Silver ions can accumulate through the food chain, causing serious health problems in species. Hence, there is a need for a commercially available silver ion sensor, with high detection sensitivity. In this work, we develop an ultra-sensitive silver ion sensor platform, using cytosine-based DNA and gold nanoparticle as the mass amplifier. We achieve a lower detection limit for silver ions of 10 pM; this detection limit is one million times lower than the toxic concentration. Using our sensor platform we examine highly selective characteristics of other typical ions in water from natural sources. Furthermore, our sensor platform is able to detect silver ions in a real practical sample of commercially available drinking water. Our sensor platform, which we have termed a 'MAIS' (Mass Amplifier Ion Sensor), with the simple detection procedure, high sensitivity, selectivity and real practical applicability has shown potential as an early toxicity assessment of silver ions for the environment.

  20. Multi-cavity coupling acoustic metamaterials with low-frequency broad band gaps based on negative mass density

    NASA Astrophysics Data System (ADS)

    Yang, Chuanhui; Wu, Jiu Hui; Cao, Songhua; Jing, Li

    2016-08-01

    This paper studies a novel kind of low-frequency broadband acoustic metamaterials with small size based on the mechanisms of negative mass density and multi-cavity coupling. The structure consists of a closed resonant cavity and an open resonant cavity, which can be equivalent to a homogeneous medium with effective negative mass density in a certain frequency range by using the parameter inversion method. The negative mass density makes the anti-resonance area increased, which results in broadened band gaps greatly. Owing to the multi-cavity coupling mechanism, the local resonances of the lower frequency mainly occur in the closed cavity, while the local resonances of the higher frequency mainly in the open cavity. Upon the interaction between the negative mass density and the multi-cavity coupling, there exists two broad band gaps in the range of 0-1800 Hz, i.e. the first-order band gap from 195 Hz to 660 Hz with the bandwidth of 465 Hz and the second-order band gap from 1157 Hz to 1663 Hz with the bandwidth of 506 Hz. The acoustic metamaterials with small size presented in this paper could provide a new approach to reduce the low-frequency broadband noises.

  1. A Geometric Modelling Approach to Determining the Best Sensing Coverage for 3-Dimensional Acoustic Target Tracking in Wireless Sensor Networks

    PubMed Central

    Pashazadeh, Saeid; Sharifi, Mohsen

    2009-01-01

    Existing 3-dimensional acoustic target tracking methods that use wired/wireless networked sensor nodes to track targets based on four sensing coverage do not always compute the feasible spatio-temporal information of target objects. To investigate this discrepancy in a formal setting, we propose a geometric model of the target tracking problem alongside its equivalent geometric dual model that is easier to solve. We then study and prove some properties of dual model by exploiting its relationship with algebra. Based on these properties, we propose a four coverage axis line method based on four sensing coverage and prove that four sensing coverage always yields two dual correct answers; usually one of them is infeasible. By showing that the feasible answer can be only sometimes identified by using a simple time test method such as the one proposed by ourselves, we prove that four sensing coverage fails to always yield the feasible spatio-temporal information of a target object. We further prove that five sensing coverage always gives the feasible position of a target object under certain conditions that are discussed in this paper. We propose three extensions to four coverage axis line method, namely, five coverage extent point method, five coverage extended axis lines method, and five coverage redundant axis lines method. Computation and time complexities of all four proposed methods are equal in the worst cases as well as on average being equal to Θ(1) each. Proposed methods and proved facts about capabilities of sensing coverage degree in this paper can be used in all other methods of acoustic target tracking like Bayesian filtering methods. PMID:22423198

  2. Sensoring Fusion Data from the Optic and Acoustic Emissions of Electric Arcs in the GMAW-S Process for Welding Quality Assessment

    PubMed Central

    Alfaro, Sadek Crisóstomo Absi; Cayo, Eber Huanca

    2012-01-01

    The present study shows the relationship between welding quality and optical-acoustic emissions from electric arcs, during welding runs, in the GMAW-S process. Bead on plate welding tests was carried out with pre-set parameters chosen from manufacturing standards. During the welding runs interferences were induced on the welding path using paint, grease or gas faults. In each welding run arc voltage, welding current, infrared and acoustic emission values were acquired and parameters such as arc power, acoustic peaks rate and infrared radiation rate computed. Data fusion algorithms were developed by assessing known welding quality parameters from arc emissions. These algorithms have showed better responses when they are based on more than just one sensor. Finally, it was concluded that there is a close relation between arc emissions and quality in welding and it can be measured from arc emissions sensing and data fusion algorithms. PMID:22969330

  3. Sensoring fusion data from the optic and acoustic emissions of electric arcs in the GMAW-S process for welding quality assessment.

    PubMed

    Alfaro, Sadek Crisóstomo Absi; Cayo, Eber Huanca

    2012-01-01

    The present study shows the relationship between welding quality and optical-acoustic emissions from electric arcs, during welding runs, in the GMAW-S process. Bead on plate welding tests was carried out with pre-set parameters chosen from manufacturing standards. During the welding runs interferences were induced on the welding path using paint, grease or gas faults. In each welding run arc voltage, welding current, infrared and acoustic emission values were acquired and parameters such as arc power, acoustic peaks rate and infrared radiation rate computed. Data fusion algorithms were developed by assessing known welding quality parameters from arc emissions. These algorithms have showed better responses when they are based on more than just one sensor. Finally, it was concluded that there is a close relation between arc emissions and quality in welding and it can be measured from arc emissions sensing and data fusion algorithms.

  4. Applications of signal multiplexing in fiber optic-based acoustic and seismic sensors

    NASA Astrophysics Data System (ADS)

    Costley, R. D.; Folks, William R.; Kirkendall, Clay K.; Galan-Comas, Gustavo; Smith, Eric W.; Parker, Michael W.; Hathaway, Kent K.

    2016-05-01

    Fiber optic systems are deployed in a variety of settings as strain sensors to locate small disturbances along the length of the optical fiber cable, which is often tens of kilometers long. This technology has the advantages of low cost and design simplicity, as the sensor is its own source of telemetry and may be easily repaired or replaced. One of the limitations of current technology is noise from optical backscatter events in the fiber resulting in a degraded signal in individual spatial zones leading to signal fading. Detection within these zones along the length of the fiber is then obscured. Signal multiplexing may be used to increase sensitivity and signal-to-noise ratio and reduce signal fading. In such an architecture, multiple channels are multiplexed together and transmitted along the fiber. In this article, we report on results from two different systems that were tested using such techniques. Results are then compared with a single channel system.

  5. Acoustic wave (AW) based moisture sensor for use with corrosive gases

    DOEpatents

    Pfeifer, K.B.; Frye, G.C.; Schneider, T.W.

    1996-11-05

    Moisture corrosive gas stream is measured as a function of the difference in resonant frequencies between two acoustic wave (AW) devices, each with a film which accepts at least one of the components of the gas stream. One AW is located in the gas stream while the other is located outside the gas stream but in the same thermal environment. In one embodiment, the film is a hydrophilic material such as SiO{sub 2}. In another embodiment, the SiO{sub 2} is covered with another film which is impermeable to the corrosive gas, such that the AW device in the gas stream measures only the water vapor. In yet another embodiment, the film comprises polyethylene oxide which is hydrophobic and measures only the partial pressure of the corrosive gas. Other embodiments allow for compensation of drift in the system. 8 figs.

  6. Acoustic wave (AW) based moisture sensor for use with corrosive gases

    DOEpatents

    Pfeifer, Kent B.; Frye, Gregory C.; Schneider, Thomas W.

    1996-01-01

    Moisture corrosive gas stream is measured as a function of the difference in resonant frequencies between two acoustic wave (AW) devices, each with a film which accepts at least one of the components of the gas stream. One AW is located in the gas stream while the other is located outside the gas stream but in the same thermal environment. In one embodiment, the film is a hydrophilic material such as SiO.sub.2. In another embodiment, the SiO.sub.2 is covered with another film which is impermeable to the corrosive gas, such that the AW device in the gas stream measures only the water vapor. In yet another embodiment, the film comprises polyethylene oxide which is hydrophobic and measures only the partial pressure of the corrosive gas. Other embodiments allow for compensation of drift in the system.

  7. Time-Efficient High-Rate Data Flooding in One-Dimensional Acoustic Underwater Sensor Networks

    PubMed Central

    Kwon, Jae Kyun; Seo, Bo-Min; Yun, Kyungsu; Cho, Ho-Shin

    2015-01-01

    Because underwater communication environments have poor characteristics, such as severe attenuation, large propagation delays and narrow bandwidths, data is normally transmitted at low rates through acoustic waves. On the other hand, as high traffic has recently been required in diverse areas, high rate transmission has become necessary. In this paper, transmission/reception timing schemes that maximize the time axis use efficiency to improve the resource efficiency for high rate transmission are proposed. The excellence of the proposed scheme is identified by examining the power distributions by node, rate bounds, power levels depending on the rates and number of nodes, and network split gains through mathematical analysis and numerical results. In addition, the simulation results show that the proposed scheme outperforms the existing packet train method. PMID:26528983

  8. Graphene-like nano-sheets for surface acoustic wave gas sensor applications

    NASA Astrophysics Data System (ADS)

    Arsat, R.; Breedon, M.; Shafiei, M.; Spizziri, P. G.; Gilje, S.; Kaner, R. B.; Kalantar-zadeh, K.; Wlodarski, W.

    2009-01-01

    The gas sensing properties of graphene-like nano-sheets deposited on 36° YX lithium tantalate (LiTaO 3) surface acoustic wave (SAW) transducers are reported. The thin graphene-like nano-sheets were produced via the reduction of graphite oxide which was deposited on SAW interdigitated transducers (IDTs). Their sensing performance was assessed towards hydrogen (H 2) and carbon monoxide (CO) in a synthetic air carrier gas at room temperature (25 °C) and 40 °C. Raman and X-ray photoelectron spectroscopy (XPS) revealed that the deposited graphite oxide (GO) was not completely reduced creating small, graphitic nanocrystals ˜2.7 nm in size.

  9. Localization with Sparse Acoustic Sensor Network Using UAVs as Information-Seeking Data Mules

    DTIC Science & Technology

    2013-05-01

    effects of environmental phenomena. Categories and Subject Descriptors: C.2 [ Computer -Communication Networks]: Network Architecture and Design; C.3...of California, Santa Barbara, CA 93106- 9560. c©2013 Association for Computing Machinery. ACM acknowledges that this contribution was authored or co...both time-of-arrival and angle- of-arrival measurements. A novel “minimal sensor subsets” approach results in a dramatic reduction in computation

  10. Long-term Acoustic Real-Time Sensor for Polar Areas (LARA)

    DTIC Science & Technology

    2013-09-30

    Volcano and the Middle Valley Ridge segment in the northeast Pacific Ocean. Both areas have seafloor volcanic eruptions forecast for the near future...Sensor for Polar Areas (LARA) for real-time monitoring of marine mammals, ambient noise levels, seismic activities (e.g., eruption of undersea volcanoes...LARA technology will be useful for real-time monitoring of deep-ocean seismic and volcanic activity (e.g., Dziak et al., 2011) - especially in areas

  11. Multiple Event Localization in a Sparse Acoustic Sensor Network Using UAVs as Data Mules

    DTIC Science & Technology

    2012-12-01

    a Microhard radio to forward the ToAs to the mule-UAV. Two Procerus Unicorn UAVs were used with different payloads. The imaging- UAV was equipped...particularly useful when the regions overlap. We present results from a field test in Section IV and conclude in Section V. II. MULTIPLE EVENT LOCALIZATION...Path taken by mule-UAV during tests . The desired path was sent to autopilot via square waypoints. The sensors and communication regions are

  12. Protecting Secure Facilities From Underground Intrusion Using Seismic/Acoustic Sensor Arrays

    DTIC Science & Technology

    2009-08-01

    reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of...centered on data collection from a tunnel the team dug at the interface of the compact-ed silt layers and the unconsolidated coarse sand layer. The sensor...array was placed at right angles to the tunnel and data collected over several days.6 This data was used to populate the computer algorithms and

  13. Multi-sensor Oceanographic Correlations for Pacific Hake Acoustic Survey Improvement

    NASA Astrophysics Data System (ADS)

    Brozen, M.; Hillyer, N.; Holt, B.; Armstrong, E. M.

    2010-12-01

    North Pacific hake (Merluccius productus), the most abundant groundfish along the Pacific coast of northwestern America, are an essential source of income for the coastal region from southern California to British Columbia, Canada. However, hake abundance and distribution are highly variable among years, exhibiting variance in both the north-south and east-west distribution as seen in the results from biannual acoustic surveys. This project is part of a larger undertaking, ultimately focused on the prediction of hake distribution to improve the distribution of survey effort and precision of stock assessments in the future. Four remotely sensed oceanographic variables are examined as a first step in improving our understanding the relationship between the intensity of coastal upwelling and other ocean dynamics, and the north-south summer hake distribution. Sea surface height, wind vectors, chlorophyll - a concentrations, and sea surface temperature were acquired from several satellites, including AVHRR, SeaWifs, TOPEX/Poseidon, Jason-1, Jason-2, SSM/I, ASMR-E, and QuikScat. Data were aligned to the same spatial and temporal resolution, and these re-gridded data were then analyzed using empirical orthogonal functions (EOFs). EOFs were used as a spatio-temporally compact representation of the data and to reduce the co-variability of the multiple time series in the dataset. The EOF results were plotted and acoustic survey results were overlaid to understand differences between regions. Although this pilot project used data from only a single year (2007), it demonstrated a methodology for reducing dimensionality of linearly related satellite variables that can used in future applications, and provided insight into multi-dimensional ocean characteristics important for hake distribution.

  14. Modeling, design, packing and experimental analysis of liquid-phase shear-horizontal surface acoustic wave sensors

    NASA Astrophysics Data System (ADS)

    Pollard, Thomas B

    Recent advances in microbiology, computational capabilities, and microelectromechanical-system fabrication techniques permit modeling, design, and fabrication of low-cost, miniature, sensitive and selective liquid-phase sensors and lab-on-a-chip systems. Such devices are expected to replace expensive, time-consuming, and bulky laboratory-based testing equipment. Potential applications for devices include: fluid characterization for material science and industry; chemical analysis in medicine and pharmacology; study of biological processes; food analysis; chemical kinetics analysis; and environmental monitoring. When combined with liquid-phase packaging, sensors based on surface-acoustic-wave (SAW) technology are considered strong candidates. For this reason such devices are focused on in this work; emphasis placed on device modeling and packaging for liquid-phase operation. Regarding modeling, topics considered include mode excitation efficiency of transducers; mode sensitivity based on guiding structure materials/geometries; and use of new piezoelectric materials. On packaging, topics considered include package interfacing with SAW devices, and minimization of packaging effects on device performance. In this work novel numerical models are theoretically developed and implemented to study propagation and transduction characteristics of sensor designs using wave/constitutive equations, Green's functions, and boundary/finite element methods. Using developed simulation tools that consider finite-thickness of all device electrodes, transduction efficiency for SAW transducers with neighboring uniform or periodic guiding electrodes is reported for the first time. Results indicate finite electrode thickness strongly affects efficiency. Using dense electrodes, efficiency is shown to approach 92% and 100% for uniform and periodic electrode guiding, respectively; yielding improved sensor detection limits. A numerical sensitivity analysis is presented targeting viscosity

  15. Temperature-stabilized silicon-based surface-acoustic-wave gas sensors for the detection of solvent vapors

    NASA Astrophysics Data System (ADS)

    Bender, Stefan; Mokwa, W.

    1998-12-01

    In the current paper a dual-delay-line- and a resonator- device based on CMOS-silicon-technology is presented. As a piezoelectric layer ZnO is used. The layer was deposited at room temperature in a RF magnetron sputter process. Using x- ray diffraction it could be shown that the crystals are mostly oriented with the c-axis (hexagonal structure) perpendicular to the surface which is necessary to conduct surface acoustic waves. Pt electrodes were designed for frequencies between 140 and 600 MHz and were deposited on top using a lift-off-process. A poly-silicon heating resistor was integrated as a sublayer for controlling and changing of the temperature of the SAW-device for studying the influence of temperature on the mass sensitive layer. A Pt thin film resistance served for temperature measurement. The performance of the devices were compared to standard quartz based SAWs.

  16. Selective Surface Acoustic Wave-Based Organophosphorus Sensor Employing a Host-Guest Self-Assembly Monolayer of β-Cyclodextrin Derivative

    PubMed Central

    Pan, Yong; Mu, Ning; Shao, Shengyu; Yang, Liu; Wang, Wen; Xie, Xiao; He, Shitang

    2015-01-01

    Self-assembly and molecular imprinting technologies are very attractive technologies for the development of artificial recognition systems and provide chemical recognition based on need and not happenstance. In this paper, we employed a β-cyclodextrin derivative surface acoustic wave (SAW) chemical sensor for detecting the chemical warfare agents (CWAs) sarin (O-Isoprophyl methylphosphonofluoridate, GB). Using sarin acid (isoprophyl hydrogen methylphosphonate) as an imprinting template, mono[6-deoxy-6-[(mercaptodecamethylene)thio

  17. Acoustic biosensors

    PubMed Central

    Fogel, Ronen; Seshia, Ashwin A.

    2016-01-01

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. PMID:27365040

  18. Acoustic biosensors.

    PubMed

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

    2016-06-30

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

  19. Mass and Force Sensing of an Adsorbate on a Beam Resonator Sensor

    PubMed Central

    Zhang, Yin; Zhao, Ya-Pu

    2015-01-01

    The mass sensing superiority of a micro-/nano-mechanical resonator sensor over conventional mass spectrometry has been, or at least is being firmly established. Because the sensing mechanism of a mechanical resonator sensor is the shifts of resonant frequencies, how to link the shifts of resonant frequencies with the material properties of an analyte formulates an inverse problem. Besides the analyte/adsorbate mass, many other factors, such as position and axial force, can also cause the shifts of resonant frequencies. The in situ measurement of the adsorbate position and axial force is extremely difficult if not impossible, especially when an adsorbate is as small as a molecule or an atom. Extra instruments are also required. In this study, an inverse problem of using three resonant frequencies to determine the mass, position and axial force is formulated and solved. The accuracy of the inverse problem solving method is demonstrated, and how the method can be used in the real application of a nanomechanical resonator is also discussed. Solving the inverse problem is helpful to the development and application of a mechanical resonator sensor for two reasons: reducing extra experimental equipment and achieving better mass sensing by considering more factors. PMID:26115457

  20. Semen quality detection using time of flight and acoustic wave sensors

    SciTech Connect

    Newton, M. I.; Evans, C. R.; Simons, J. J.; Hughes, D. C.

    2007-04-09

    The authors report a real-time technique for assessing the number of motile sperm in a semen sample. The time of flight technique uses a flow channel with detection at the end of the channel using quartz crystal microbalances. Data presented suggest that a simple rigid mass model may be used in interpreting the change in resonant frequency using an effective mass for the sperm.

  1. Sensor apparatus

    DOEpatents

    Deason, Vance A [Idaho Falls, ID; Telschow, Kenneth L [Idaho Falls, ID

    2009-12-22

    A sensor apparatus and method for detecting an environmental factor is shown that includes an acoustic device that has a characteristic resonant vibrational frequency and mode pattern when exposed to a source of acoustic energy and, futher, when exposed to an environmental factor, produces a different resonant vibrational frequency and/or mode pattern when exposed to the same source of acoustic energy.

  2. Underwater Acoustic Wireless Sensor Networks: Advances and Future Trends in Physical, MAC and Routing Layers

    PubMed Central

    Climent, Salvador; Sanchez, Antonio; Capella, Juan Vicente; Meratnia, Nirvana; Serrano, Juan Jose

    2014-01-01

    This survey aims to provide a comprehensive overview of the current research on underwater wireless sensor networks, focusing on the lower layers of the communication stack, and envisions future trends and challenges. It analyzes the current state-of-the-art on the physical, medium access control and routing layers. It summarizes their security threads and surveys the currently proposed studies. Current envisioned niches for further advances in underwater networks research range from efficient, low-power algorithms and modulations to intelligent, energy-aware routing and medium access control protocols. PMID:24399155

  3. Rapid determination of floral aroma compounds of lilac blossom by fast gas chromatography combined with surface acoustic wave sensor.

    PubMed

    Oh, Se Yeon; Shin, Hyun Du; Kim, Sung Jean; Hong, Jongki

    2008-03-07

    A novel analytical method using fast gas chromatography combined with surface acoustic wave sensor (GC/SAW) has been developed for the detection of volatile aroma compounds emanated from lilac blossom (Syringa species: Syringa vulgaris variginata and Syringa dilatata). GC/SAW could detect and quantify various fragrance emitted from lilac blossom, enabling to provide fragrance pattern analysis results. The fragrance pattern analysis could easily characterize the delicate differences in aromas caused by the substantial difference of chemical composition according to different color and shape of petals. Moreover, the method validation of GC/SAW was performed for the purpose of volatile floral actual aroma analysis, achieving a high reproducibility and excellent sensitivity. From the validation results, GC/SAW could serve as an alternative analytical technique for the analysis of volatile floral actual aroma of lilac. In addition, headspace solid-phase microextraction (HS-SPME) GC-MS was employed to further confirm the identification of fragrances emitted from lilac blossom and compared to GC/SAW.

  4. Hybrid organic/inorganic copolymers with strongly hydrogen-bond acidic properties for acoustic wave and optical sensors

    SciTech Connect

    Grate, J.W.; Kaganove, S.N.; Patrash, S.J.

    1997-05-01

    Hybrid organic/inorganic polymers have been prepared incorporating fluoroalkyl-substituted bisphenol groups linked using oligosiloxane spacers. These hydrogen-bond acidic materials have glass-to-rubber transition temperatures below room temperature and are excellent sorbents for basic vapors. The physical properties such as viscosity and refractive index can be tuned by varying the length of the oligosiloxane spacers and the molecular weight. In addition, the materials are easily cross-linked to yield solid elastomers. The potential use of these materials for chemical sensing has been demonstrated by applying them to surface acoustic wave devices as thin films and detecting the hydrogen-bond basic vapor dimethyl methylphosphonate with high sensitivity. It has also been demonstrated that one of these materials with suitable viscosity and refractive index can be used to clad silica optical fibers; the cladding was applied to freshly drawn fiber using a fiber drawing tower. These fibers have potential as evanescent wave optical fiber sensors. 38 refs., 2 figs.

  5. On the Acoustic Filtering of the Pipe and Sensor in a Buried Plastic Water Pipe and its Effect on Leak Detection: An Experimental Investigation

    PubMed Central

    Almeida, Fabrício; Brennan, Michael; Joseph, Phillip; Whitfield, Stuart; Dray, Simon; Paschoalini, Amarildo

    2014-01-01

    Acoustic techniques have been used for many years to find and locate leaks in buried water distribution systems. Hydrophones and accelerometers are typically used as sensors. Although geophones could be used as well, they are not generally used for leak detection. A simple acoustic model of the pipe and the sensors has been proposed previously by some of the authors of this paper, and their model was used to explain some of the features observed in measurements. However, simultaneous measurements of a leak using all three sensor-types in controlled conditions for plastic pipes has not been reported to-date and hence they have not yet been compared directly. This paper fills that gap in knowledge. A set of measurements was made on a bespoke buried plastic water distribution pipe test rig to validate the previously reported analytical model. There is qualitative agreement between the experimental results and the model predictions in terms of the differing filtering properties of the pipe-sensor systems. A quality measure for the data is also presented, which is the ratio of the bandwidth over which the analysis is carried out divided by the centre frequency of this bandwidth. Based on this metric, the accelerometer was found to be the best sensor to use for the test rig described in this paper. However, for a system in which the distance between the sensors is large or the attenuation factor of the system is high, then it would be advantageous to use hydrophones, even though they are invasive sensors. PMID:24658622

  6. High-frequency acoustic sensors for operation in a gaseous medium. Final report

    SciTech Connect

    Kino, G.S.

    1990-12-31

    Photothermal microscopy is a technique for measuring thermal properties on a small scale by using focused laser beams as heat sources and as temperature probes. Typically used for nondestructive evaluation (NDE) of materials, its main advantage is its ability to measure types of flaws that are not visible optically or acoustically. Because of the optical nature of photothermal microscopy, sub-micron resolutions can be obtained in many of these thermal measurements. The greatest limitation of these systems is their relatively poor signal-to-noise ratios and, consequently, slow imaging speeds. To circumvent this problem, a variety of approaches to the detection of thermal waves has been pursued in recent years. This thesis compares the relative merits of a common class of techniques that rely on direct observation of physical changes in the heated sample, including a novel approach to interferometric measurement of the thermal expansion. It is found that the optimum approach depends not only on the physical properties of the sample being studies, but also upon the resolution of the experiment and the damage threshold of the specimen. Finally, this dissertation describes the applications of photothermal microscopy to the study of the anisotropic thermal properties of the new high-{Tc} superconductors. By adding a high-vacuum cryostat to the microscope, the authors have been able to study the influence of the superconducting transition on the thermal conductivity. The measurements of the anisotropic thermal conductivity demonstrate that the heat flow along the superconducting planes is enhanced below the transition, and that no such enhancement exists in the non-superconducting direction. Material examined was Bi-Ca-Sr-Cu-O.

  7. Dual-mode thin film bulk acoustic wave resonators for parallel sensing of temperature and mass loading.

    PubMed

    García-Gancedo, L; Pedrós, J; Zhao, X B; Ashley, G M; Flewitt, A J; Milne, W I; Ford, C J B; Lu, J R; Luo, J K

    2012-01-01

    Thin film bulk acoustic wave resonator (FBAR) devices supporting simultaneously multiple resonance modes have been designed for gravimetric sensing. The mechanism for dual-mode generation within a single device has been discussed, and theoretical calculations based on finite element analysis allowed the fabrication of FBARs whose resonance modes have opposite reactions to temperature changes; one of the modes exhibiting a positive frequency shift for a rise of temperature whilst the other mode exhibits a negative shift. Both modes exhibit negative frequency shift for a mass load and hence by monitoring simultaneously both modes it is possible to distinguish whether a change in the resonance frequency is due to a mass load or temperature variation (or a combination of both), avoiding false positive/negative responses in gravimetric sensing without the need of additional reference devices or complex electronics.

  8. Acoustic dose and acoustic dose-rate.

    PubMed

    Duck, Francis

    2009-10-01

    Acoustic dose is defined as the energy deposited by absorption of an acoustic wave per unit mass of the medium supporting the wave. Expressions for acoustic dose and acoustic dose-rate are given for plane-wave conditions, including temporal and frequency dependencies of energy deposition. The relationship between the acoustic dose-rate and the resulting temperature increase is explored, as is the relationship between acoustic dose-rate and radiation force. Energy transfer from the wave to the medium by means of acoustic cavitation is considered, and an approach is proposed in principle that could allow cavitation to be included within the proposed definitions of acoustic dose and acoustic dose-rate.

  9. Dependence of Dynamic Modeling Accuracy on Sensor Measurements, Mass Properties, and Aircraft Geometry

    NASA Technical Reports Server (NTRS)

    Grauer, Jared A.; Morelli, Eugene A.

    2013-01-01

    The NASA Generic Transport Model (GTM) nonlinear simulation was used to investigate the effects of errors in sensor measurements, mass properties, and aircraft geometry on the accuracy of identified parameters in mathematical models describing the flight dynamics and determined from flight data. Measurements from a typical flight condition and system identification maneuver were systematically and progressively deteriorated by introducing noise, resolution errors, and bias errors. The data were then used to estimate nondimensional stability and control derivatives within a Monte Carlo simulation. Based on these results, recommendations are provided for maximum allowable errors in sensor measurements, mass properties, and aircraft geometry to achieve desired levels of dynamic modeling accuracy. Results using additional flight conditions and parameter estimation methods, as well as a nonlinear flight simulation of the General Dynamics F-16 aircraft, were compared with these recommendations

  10. Optical mass gauge sensor having an energy per unit area of illumination detection

    NASA Technical Reports Server (NTRS)

    Justak, John F. (Inventor)

    2000-01-01

    An optical mass gauge sensor is disclosed comprising a vessel having an interior surface which reflects radiant energy at a wavelength at least partially absorbed by a fluid contained within the vessel, an illuminating device for introducing radiant energy at such wavelength into the vessel interior, and, a detector for measuring the energy per unit area of illumination within the vessel created by the radiant energy which is not absorbed by the fluid.

  11. Acoustics- Version 1.0

    SciTech Connect

    2012-09-13

    This package contains modules that model acoustic sensors and acoustic sources (hearable) in Umbra. It is typically used to represent hearing in characters within Umbra. Typically, the acoustic sensors detect acoustic sources at a given point; however, it also contains the capability to detect bullet cracks by detecting the sound along the bullet path that is closest to the sensor. A memory module, acoustic memory, represents remembered sounds within a given character. Over time, the sounds are removed, as a character forgets what it has heard.

  12. Simultaneous Moisture Content and Mass Flow Measurements in Wood Chip Flows Using Coupled Dielectric and Impact Sensors.

    PubMed

    Pan, Pengmin; McDonald, Timothy; Fulton, John; Via, Brian; Hung, John

    2016-12-23

    An 8-electrode capacitance tomography (ECT) sensor was built and used to measure moisture content (MC) and mass flow of pine chip flows. The device was capable of directly measuring total water quantity in a sample but was sensitive to both dry matter and moisture, and therefore required a second measurement of mass flow to calculate MC. Two means of calculating the mass flow were used: the first being an impact sensor to measure total mass flow, and the second a volumetric approach based on measuring total area occupied by wood in images generated using the capacitance sensor's tomographic mode. Tests were made on 109 groups of wood chips ranging in moisture content from 14% to 120% (dry basis) and wet weight of 280 to 1100 g. Sixty groups were randomly selected as a calibration set, and the remaining were used for validation of the sensor's performance. For the combined capacitance/force transducer system, root mean square errors of prediction (RMSEP) for wet mass flow and moisture content were 13.42% and 16.61%, respectively. RMSEP using the combined volumetric mass flow/capacitance sensor for dry mass flow and moisture content were 22.89% and 24.16%, respectively. Either of the approaches was concluded to be feasible for prediction of moisture content in pine chip flows, but combining the impact and capacitance sensors was easier to implement. In situations where flows could not be impeded, however, the tomographic approach would likely be more useful.

  13. Magnetoelastic sensors for remote query environmental monitoring

    NASA Astrophysics Data System (ADS)

    Grimes, C. A.; Ong, K. G.; Loiselle, K.; Stoyanov, P. G.; Kouzoudis, D.; Liu, Y.; Tong, C.; Tefiku, F.

    1999-10-01

    Magnetoelastic thin film sensors can be considered the magnetic analog of surface acoustic wave sensors, with the characteristic resonant frequency of the magnetoelastic sensor changing in response to different environmental parameters. We report on the application of magnetoelastic sensors for remote query measurement of pressure, temperature, liquid viscosity and, in combination with a glucose-responding mass-changing polymer, glucose concentrations. The advantage of using magnetoelastic sensors is that no direct physical connections, such as wires or cables, are required to obtain sensor information allowing the sensor to be monitored from inside sealed containers. Furthermore since it is the frequency response of the sensor that is monitored, rather than the amplitude, the relative orientation of the sensor with respect to the query field is unimportant.

  14. Improvement of optical and acoustical technologies for the protection: Project IMOTEP: Network of heterogeneous sensor types for the protection of camps or mobile troops

    NASA Astrophysics Data System (ADS)

    Hengy, Sébastien; Laurenzis, Martin; Zimpfer, Véronique; Schneider, Armin

    2014-10-01

    Snipers have emerged as a major threat to troops in recent conflicts. To reduce this menace, the objective of the French- German Research Institute of Saint Louis (ISL) research project "IMOTEP" is to improve the detection of snipers on the battlefield. Our basic approach is to combine several sources of information for a fast and appropriate reaction when an unusual signal (e.g. a flash or a shot) is detected. The project includes several technologies developed at ISL: acoustical detection, fusion of distributed sensor network data, active imaging and 3D audio communication. The protection of camps, convoys or dismounted soldiers rests on a distributed acoustical sensor network that detects and localizes sniper attacks. An early estimation of the threat position is transmitted through a network to an active imaging system in order to confirm and refine this position by 3D imaging. The refined position is then sent to the control center which generates an alert message that displays the threat position using two formats: a tactical map and a 3D audio signal. In addition, the camp is protected by an ad-hoc sensor network used for intruder detection.

  15. Analysis of binary mixtures of aqueous aromatic hydrocarbons with low-phase-noise shear-horizontal surface acoustic wave sensors using multielectrode transducer designs.

    PubMed

    Bender, Florian; Mohler, Rachel E; Ricco, Antonio J; Josse, Fabien

    2014-11-18

    The present work investigates a compact sensor system that provides rapid, real-time, in situ measurements of the identities and concentrations of aromatic hydrocarbons at parts-per-billion concentrations in water through the combined use of kinetic and thermodynamic response parameters. The system uses shear-horizontal surface acoustic wave (SH-SAW) sensors operating directly in the liquid phase. The 103 MHz SAW sensors are coated with thin sorbent polymer films to provide the appropriate limits of detection as well as partial selectivity for the analytes of interest, the BTEX compounds (benzene, toluene, ethylbenzene, and xylenes), which are common indicators of fuel and oil accidental releases in groundwater. Particular emphasis is placed on benzene, a known carcinogen and the most challenging BTEX analyte with regard to both regulated levels and its solubility properties. To demonstrate the identification and quantification of individual compounds in multicomponent aqueous samples, responses to binary mixtures of benzene with toluene as well as ethylbenzene were characterized at concentrations below 1 ppm (1 mg/L). The use of both thermodynamic and kinetic (i.e., steady-state and transient) responses from a single polymer-coated SH-SAW sensor enabled identification and quantification of the two BTEX compounds in binary mixtures in aqueous solution. The signal-to-noise ratio was improved, resulting in lower limits of detection and improved identification at low concentrations, by designing and implementing a type of multielectrode transducer pattern, not previously reported for chemical sensor applications. The design significantly reduces signal distortion and root-mean-square (RMS) phase noise by minimizing acoustic wave reflections from electrode edges, thus enabling limits of detection for BTEX analytes of 9-83 ppb (calculated from RMS noise); concentrations of benzene in water as low as ~100 ppb were measured directly. Reliable quantification of BTEX

  16. Fast surface acoustic wave-matrix-assisted laser desorption ionization mass spectrometry of cell response from islets of Langerhans.

    PubMed

    Bllaci, Loreta; Kjellström, Sven; Eliasson, Lena; Friend, James R; Yeo, Leslie Y; Nilsson, Staffan

    2013-03-05

    A desire for higher speed and performance in molecular profiling analysis at a reduced cost is driving a trend in miniaturization and simplification of procedures. Here we report the use of a surface acoustic wave (SAW) atomizer for fast sample handling in matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) peptide and protein profiling of Islets of Langerhans, for future type 2 diabetes (T2D) studies. Here the SAW atomizer was used for ultrasound (acoustic) extraction of insulin and other peptide hormones released from freshly prepared islets, stimulated directly on a membrane. A high energy propagating SAW atomizes the membrane-bound liquid into approximately 2 μm diameter droplets, rich in cell-released molecules. Besides acting as a sample carrier, the membrane provides a purification step by entrapping cell clusters and other impurities within its fibers. A new SAW-based sample-matrix deposition method for MALDI MS was developed and characterized by a strong insulin signal, and a limit of detection (LOD) lower than 100 amol was achieved. Our results support previous work reporting the SAW atomizer as a fast and inexpensive tool for ultrasound, membrane-based sample extraction. When interfaced with MALDI MS, the SAW atomizer constitutes a valuable tool for rapid cell studies. Other biomedical applications of SAW-MALDI MS are currently being developed, aiming at fast profiling of biofluids. The membrane sampling is a simplistic and noninvasive collection method of limited volume biofluids such as the gingival fluid and the tearfilm.

  17. Using a fibre-optic cable as Distributed Acoustic Sensor for Vertical Seismic Profiling - Overview of various field tests

    NASA Astrophysics Data System (ADS)

    Götz, Julia; Lüth, Stefan; Henninges, Jan; Reinsch, Thomas

    2015-04-01

    Fibre-optic Distributed Acoustic Sensing (DAS) or Distributed Vibration Sensing (DVS) is a technology, where an optical fibre cable is used as a sensor for acoustic signals. An ambient seismic wavefield, which is coupled by friction or pressure to the optical fibre, induces dynamic strain changes along the cable. The DAS/DVS technology offers the possibility to record an optoelectronic signal which is linearly related to the time dependent local strain. The DAS/DVS technology is based on the established technique of phase-sensitive optical time-domain reflectometry (phi-OTDR). Coherent laser pulses are launched into the fibre to monitor changes in the resulting elastic Rayleigh backscatter with time. Dynamic strain changes lead to small displacements of the scattering elements (non-uniformities within the glass structure of the optical fibre), and therefore to variations of the relative phases of the backscattered photons. The fibre behaves as a series of interferometers whose output is sensitive to small changes of the strain at any point along its length. To record the ground motion not only in space but also in time, snapshots of the wavefield are created by repeatedly firing laser pulses into the fibre at sampling frequencies much higher than seismic frequencies. DAS/DVS is used e.g. for continuous monitoring of pipelines, roads or borders and for production monitoring from within the wellbore. Within the last years, the DAS/DVS technology was further developed to record seismic data. We focus on the recording of Vertical Seismic Profiling (VSP) data with DAS/DVS and present an overview of various field tests published between 2011 and 2014. Here, especially CO2 storage pilot sites provided the opportunity to test this new technology for geophysical reservoir monitoring. DAS/DVS-VSP time-lapse measurements have been published for the Quest CO2 storage site in Canada. The DAS/DVS technology was also tested at the CO2 storage sites in Rousse (France), Citronelle

  18. Mass flux response comparisons of a 200-MHz surface acoustic wave (SAW) resonator microbalance to a 15-MHz thermoelectric quartz crystal microbalance (TQCM) in a high-vacuum environment

    NASA Astrophysics Data System (ADS)

    Wallace, Donald A.; Bowers, William D.

    1994-10-01

    Using a 200 MHz Surface Acoustic Wave (SAW) resonator device as a high-vacuum molecular deposition microbalance, similar to a bulk quartz crystal microbalance (QCM), and an often-used 15 MHz thermoelectric QCM (TQCM), a comparison of various parameters was made during a high-vacuum outgassing experiment. The source of molecular outgassing was a bright aluminum foil which was cooled to liquid nitrogen temperature and alternately, to ambient temperature. The two sensors, the SAW QCM and the TQCM were placed next to each other and viewed only the aluminum foil. In this high-vacuum environment, a comparison between various parameters, i.e., mass sensitivity, long term drift rate, stability, thermal effects and dynamic range of the SAW and the TQCM, was obtained.

  19. Biofilm dynamics characterization using a novel DO-MEA sensor: mass transport and biokinetics.

    PubMed

    Guimerà, Xavier; Moya, Ana; Dorado, Antonio David; Villa, Rosa; Gabriel, David; Gabriel, Gemma; Gamisans, Xavier

    2015-01-01

    Biodegradation process modeling is an essential tool for the optimization of biotechnologies related to gaseous pollutant treatment. In these technologies, the predominant role of biofilm, particularly under conditions of no mass transfer limitations, results in a need to determine what processes are occurring within the same. By measuring the interior of the biofilms, an increased knowledge of mass transport and biodegradation processes may be attained. This information is useful in order to develop more reliable models that take biofilm heterogeneity into account. In this study, a new methodology, based on a novel dissolved oxygen (DO) and mass transport microelectronic array (MEA) sensor, is presented in order to characterize a biofilm. Utilizing the MEA sensor, designed to obtain DO and diffusivity profiles with a single measurement, it was possible to obtain distributions of oxygen diffusivity and biokinetic parameters along a biofilm grown in a flat plate bioreactor (FPB). The results obtained for oxygen diffusivity, estimated from oxygenation profiles and direct measurements, revealed that changes in its distribution were reduced when increasing the liquid flow rate. It was also possible to observe the effect of biofilm heterogeneity through biokinetic parameters, estimated using the DO profiles. Biokinetic parameters, including maximum specific growth rate, the Monod half-saturation coefficient of oxygen, and the maintenance coefficient for oxygen which showed a marked variation across the biofilm, suggest that a tool that considers the heterogeneity of biofilms is essential for the optimization of biotechnologies.

  20. Estimation of Center of Mass Trajectory using Wearable Sensors during Golf Swing.

    PubMed

    Najafi, Bijan; Lee-Eng, Jacqueline; Wrobel, James S; Goebel, Ruben

    2015-06-01

    This study suggests a wearable sensor technology to estimate center of mass (CoM) trajectory during a golf swing. Groups of 3, 4, and 18 participants were recruited, respectively, for the purpose of three validation studies. Study 1 examined the accuracy of the system to estimate a 3D body segment angle compared to a camera-based motion analyzer (Vicon®). Study 2 assessed the accuracy of three simplified CoM trajectory models. Finally, Study 3 assessed the accuracy of the proposed CoM model during multiple golf swings. A relatively high agreement was observed between wearable sensors and the reference (Vicon®) for angle measurement (r > 0.99, random error <1.2° (1.5%) for anterior-posterior; <0.9° (2%) for medial-lateral; and <3.6° (2.5%) for internal-external direction). The two-link model yielded a better agreement with the reference system compared to one-link model (r > 0.93 v. r = 0.52, respectively). On the same note, the proposed two-link model estimated CoM trajectory during golf swing with relatively good accuracy (r > 0.9, A-P random error <1cm (7.7%) and <2cm (10.4%) for M-L). The proposed system appears to accurately quantify the kinematics of CoM trajectory as a surrogate of dynamic postural control during an athlete's movement and its portability, makes it feasible to fit the competitive environment without restricting surface type. Key pointsThis study demonstrates that wearable technology based on inertial sensors are accurate to estimate center of mass trajectory in complex athletic task (e.g., golf swing)This study suggests that two-link model of human body provides optimum tradeoff between accuracy and minimum number of sensor module for estimation of center of mass trajectory in particular during fast movements.Wearable technologies based on inertial sensors are viable option for assessing dynamic postural control in complex task outside of gait laboratory and constraints of cameras, surface, and base of support.

  1. Estimation of Center of Mass Trajectory using Wearable Sensors during Golf Swing

    PubMed Central

    Najafi, Bijan; Lee-Eng, Jacqueline; Wrobel, James S.; Goebel, Ruben

    2015-01-01

    This study suggests a wearable sensor technology to estimate center of mass (CoM) trajectory during a golf swing. Groups of 3, 4, and 18 participants were recruited, respectively, for the purpose of three validation studies. Study 1 examined the accuracy of the system to estimate a 3D body segment angle compared to a camera-based motion analyzer (Vicon®). Study 2 assessed the accuracy of three simplified CoM trajectory models. Finally, Study 3 assessed the accuracy of the proposed CoM model during multiple golf swings. A relatively high agreement was observed between wearable sensors and the reference (Vicon®) for angle measurement (r > 0.99, random error <1.2° (1.5%) for anterior-posterior; <0.9° (2%) for medial-lateral; and <3.6° (2.5%) for internal-external direction). The two-link model yielded a better agreement with the reference system compared to one-link model (r > 0.93 v. r = 0.52, respectively). On the same note, the proposed two-link model estimated CoM trajectory during golf swing with relatively good accuracy (r > 0.9, A-P random error <1cm (7.7%) and <2cm (10.4%) for M-L). The proposed system appears to accurately quantify the kinematics of CoM trajectory as a surrogate of dynamic postural control during an athlete’s movement and its portability, makes it feasible to fit the competitive environment without restricting surface type. Key points This study demonstrates that wearable technology based on inertial sensors are accurate to estimate center of mass trajectory in complex athletic task (e.g., golf swing) This study suggests that two-link model of human body provides optimum tradeoff between accuracy and minimum number of sensor module for estimation of center of mass trajectory in particular during fast movements. Wearable technologies based on inertial sensors are viable option for assessing dynamic postural control in complex task outside of gait laboratory and constraints of cameras, surface, and base of support. PMID:25983585

  2. Phase Velocity and Full-Waveform Analysis of Co-located Distributed Acoustic Sensing (DAS) Channels and Geophone Sensor

    NASA Astrophysics Data System (ADS)

    Parker, L.; Mellors, R. J.; Thurber, C. H.; Wang, H. F.; Zeng, X.

    2015-12-01

    A 762-meter Distributed Acoustic Sensing (DAS) array with a channel spacing of one meter was deployed at the Garner Valley Downhole Array in Southern California. The array was approximately rectangular with dimensions of 180 meters by 80 meters. The array also included two subdiagonals within the rectangle along which three-component geophones were co-located. Several active sources were deployed, including a 45-kN, swept-frequency, shear-mass shaker, which produced strong Rayleigh waves across the array. Both DAS and geophone traces were filtered in 2-Hz steps between 4 and 20 Hz to obtain phase velocities as a function of frequency from fitting the moveout of travel times over distances of 35 meters or longer. As an alternative to this traditional means of finding phase velocity, it is theoretically possible to find the Rayleigh-wave phase velocity at each point of co-location as the ratio of DAS and geophone responses, because DAS is sensitive to ground strain and geophones are sensitive to ground velocity, after suitable corrections for instrument response (Mikumo & Aki, 1964). The concept was tested in WPP, a seismic wave propagation program, by first validating and then using a 3D synthetic, full-waveform seismic model to simulate the effect of increased levels of noise and uncertainty as data go from ideal to more realistic. The results obtained from this study provide a better understanding of the DAS response and its potential for being combined with traditional seismometers for obtaining phase velocity at a single location. This analysis is part of the PoroTomo project (Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology, http://geoscience.wisc.edu/feigl/porotomo).

  3. Bridged single-walled carbon nanotube-based atomic-scale mass sensors

    NASA Astrophysics Data System (ADS)

    Ali-Akbari, H. R.; Shaat, M.; Abdelkefi, A.

    2016-08-01

    The potentials of carbon nanotubes (CNTs) as mechanical resonators for atomic-scale mass sensing are presented. To this aim, a nonlocal continuum-based model is proposed to study the dynamic behavior of bridged single-walled carbon nanotube-based mass nanosensors. The carbon nanotube (CNT) is considered as an elastic Euler-Bernoulli beam with von Kármán type geometric nonlinearity. Eringen's nonlocal elastic field theory is utilized to model the interatomic long-range interactions within the structure of the CNT. This developed model accounts for the arbitrary position of the deposited atomic-mass. The natural frequencies and associated mode shapes are determined based on an eigenvalue problem analysis. An atom of xenon (Xe) is first considered as a specific case where the results show that the natural frequencies and mode shapes of the CNT are strongly dependent on the location of the deposited Xe and the nonlocal parameter of the CNT. It is also indicated that the first vibrational mode is the most sensitive when the mass is deposited at the middle of a single-walled carbon nanotube. However, when deposited in other locations, it is demonstrated that the second or third vibrational modes may be more sensitive. To investigate the sensitivity of bridged single-walled CNTs as mass sensors, different noble gases are considered, namely Xe, argon (Ar), and helium (He). It is shown that the sensitivity of the single-walled CNT to the Ar and He gases is much lower than the Xe gas due to the significant decrease in their masses. The derived model and performed analysis are so needed for mass sensing applications and particularly when the detected mass is randomly deposited.

  4. Acoustic Source Localization via Time Difference of Arrival Estimation for Distributed Sensor Networks using Tera-scale Optical-Core Devices

    SciTech Connect

    Imam, Neena; Barhen, Jacob

    2009-01-01

    For real-time acoustic source localization applications, one of the primary challenges is the considerable growth in computational complexity associated with the emergence of ever larger, active or passive, distributed sensor networks. These sensors rely heavily on battery-operated system components to achieve highly functional automation in signal and information processing. In order to keep communication requirements minimal, it is desirable to perform as much processing on the receiver platforms as possible. However, the complexity of the calculations needed to achieve accurate source localization increases dramatically with the size of sensor arrays, resulting in substantial growth of computational requirements that cannot be readily met with standard hardware. One option to meet this challenge builds upon the emergence of digital optical-core devices. The objective of this work was to explore the implementation of key building block algorithms used in underwater source localization on the optical-core digital processing platform recently introduced by Lenslet Inc. This demonstration of considerably faster signal processing capability should be of substantial significance to the design and innovation of future generations of distributed sensor networks.

  5. Chemical discrimination in turbulent gas mixtures with MOX sensors validated by gas chromatography-mass spectrometry.

    PubMed

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-10-16

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance.

  6. Experimental investigation on mass flow rate measurements using fibre Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Thekkethil, S. R.; Thomas, R. J.; Neumann, H.; Ramalingam, R.

    2017-02-01

    Flow measurement and control of cryogens is one of the major requirements of systems such as superconductor magnets for fusion reactors, MRI magnets etc. They can act as an early diagnostic tool for detection of any faults and ensure correct distribution of cooling load while also accessing thermal performance of the devices. Fibre Bragg Grating (FBG) sensors provide compact and accurate measurement systems which have added advantages such as immunity towards electrical and magnetic interference, low attenuation losses and remote sensing. This paper summarizes the initial experimental investigations and calibration of a novel FBG based mass flow meter. This design utilizes the viscous drag due to the flow to induce a bending strain on the fibre. The strain experienced by the fibre will be proportional to the flowrate and can be measured in terms of Bragg wavelength shift. The flowmeter is initially tested at atmospheric conditions using helium. The results are summarized and the performance parameters of the sensor are estimated. The results were also compared to a numerical model and further results for liquid helium is also reported. An overall sensitivity of 29 pm.(g.s-1)-1 was obtained for a helium flow, with a resolution of 0.2 g.s-1. A hysteresis error of 8 pm was also observed during load-unload cycles. The sensor is suitable for further tests using cryogens.

  7. D Capturing Performances of Low-Cost Range Sensors for Mass-Market Applications

    NASA Astrophysics Data System (ADS)

    Guidi, G.; Gonizzi, S.; Micoli, L.

    2016-06-01

    Since the advent of the first Kinect as motion controller device for the Microsoft XBOX platform (November 2010), several similar active and low-cost range sensing devices have been introduced on the mass-market for several purposes, including gesture based interfaces, 3D multimedia interaction, robot navigation, finger tracking, 3D body scanning for garment design and proximity sensors for automotive. However, given their capability to generate a real time stream of range images, these has been used in some projects also as general purpose range devices, with performances that for some applications might be satisfying. This paper shows the working principle of the various devices, analyzing them in terms of systematic errors and random errors for exploring the applicability of them in standard 3D capturing problems. Five actual devices have been tested featuring three different technologies: i) Kinect V1 by Microsoft, Structure Sensor by Occipital, and Xtion PRO by ASUS, all based on different implementations of the Primesense sensor; ii) F200 by Intel/Creative, implementing the Realsense pattern projection technology; Kinect V2 by Microsoft, equipped with the Canesta TOF Camera. A critical analysis of the results tries first of all to compare them, and secondarily to focus the range of applications for which such devices could actually work as a viable solution.

  8. Miniature Biomimetic Acoustic Sensors

    DTIC Science & Technology

    1999-08-01

    Toronto M5S 3G4, Canada *Center for Computational Astrobiology NASA Ames Research Center Moffett Field, CA 1 New appointment: DARPA (MEMS program...internal gas flows have already been computed at the Center for Computational Astrobiology (NASA Ames) • A JPL-Ames collaborative effort is in place to

  9. Development and evaluation of virtual refrigerant mass flow sensors for fault detection and diagnostics

    SciTech Connect

    Kim, Woohyun; Braun, J.

    2016-03-05

    Refrigerant mass flow rate is an important measurement for monitoring equipment performance and enabling fault detection and diagnostics. However, a traditional mass flow meter is expensive to purchase and install. A virtual refrigerant mass flow sensor (VRMF) uses a mathematical model to estimate flow rate using low-cost measurements and can potentially be implemented at low cost. This study evaluates three VRMFs for estimating refrigerant mass flow rate. The first model uses a compressor map that relates refrigerant flow rate to measurements of inlet and outlet pressure, and inlet temperature measurements. The second model uses an energy-balance method on the compressor that uses a compressor map for power consumption, which is relatively independent of compressor faults that influence mass flow rate. The third model is developed using an empirical correlation for an electronic expansion valve (EEV) based on an orifice equation. The three VRMFs are shown to work well in estimating refrigerant mass flow rate for various systems under fault-free conditions with less than 5% RMS error. Each of the three mass flow rate estimates can be utilized to diagnose and track the following faults: 1) loss of compressor performance, 2) fouled condenser or evaporator filter, 3) faulty expansion device, respectively. For example, a compressor refrigerant flow map model only provides an accurate estimation when the compressor operates normally. When a compressor is not delivering the expected flow due to a leaky suction or discharge valve or other internal fault, the energy-balance or EEV model can provide accurate flow estimates. In this paper, the flow differences provide an indication of loss of compressor performance and can be used for fault detection and diagnostics.

  10. Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocity.

    PubMed

    Bugbee, B; Monje, O; Tanner, B

    1996-01-01

    Here we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature.

  11. Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocity

    NASA Technical Reports Server (NTRS)

    Bugbee, B.; Monje, O.; Tanner, B.

    1996-01-01

    Here we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature.

  12. Cryogenic Flow Sensor

    NASA Technical Reports Server (NTRS)

    Justak, John

    2010-01-01

    An acousto-optic cryogenic flow sensor (CFS) determines mass flow of cryogens for spacecraft propellant management. The CFS operates unobtrusively in a high-pressure, high-flowrate cryogenic environment to provide measurements for fluid quality as well as mass flow rate. Experimental hardware uses an optical plane-of-light (POL) to detect the onset of two-phase flow, and the presence of particles in the flow of water. Acousto-optic devices are used in laser equipment for electronic control of the intensity and position of the laser beam. Acousto-optic interaction occurs in all optical media when an acoustic wave and a laser beam are present. When an acoustic wave is launched into the optical medium, it generates a refractive index wave that behaves like a sinusoidal grating. An incident laser beam passing through this grating will diffract the laser beam into several orders. Its angular position is linearly proportional to the acoustic frequency, so that the higher the frequency, the larger the diffracted angle. If the acoustic wave is traveling in a moving fluid, the fluid velocity will affect the frequency of the traveling wave, relative to a stationary sensor. This frequency shift changes the angle of diffraction, hence, fluid velocity can be determined from the diffraction angle. The CFS acoustic Bragg grating data test indicates that it is capable of accurately determining flow from 0 to 10 meters per second. The same sensor can be used in flow velocities exceeding 100 m/s. The POL module has successfully determined the onset of two-phase flow, and can distinguish vapor bubbles from debris.

  13. Simultaneous Moisture Content and Mass Flow Measurements in Wood Chip Flows Using Coupled Dielectric and Impact Sensors

    PubMed Central

    Pan, Pengmin; McDonald, Timothy; Fulton, John; Via, Brian; Hung, John

    2016-01-01

    An 8-electrode capacitance tomography (ECT) sensor was built and used to measure moisture content (MC) and mass flow of pine chip flows. The device was capable of directly measuring total water quantity in a sample but was sensitive to both dry matter and moisture, and therefore required a second measurement of mass flow to calculate MC. Two means of calculating the mass flow were used: the first being an impact sensor to measure total mass flow, and the second a volumetric approach based on measuring total area occupied by wood in images generated using the capacitance sensor’s tomographic mode. Tests were made on 109 groups of wood chips ranging in moisture content from 14% to 120% (dry basis) and wet weight of 280 to 1100 g. Sixty groups were randomly selected as a calibration set, and the remaining were used for validation of the sensor’s performance. For the combined capacitance/force transducer system, root mean square errors of prediction (RMSEP) for wet mass flow and moisture content were 13.42% and 16.61%, respectively. RMSEP using the combined volumetric mass flow/capacitance sensor for dry mass flow and moisture content were 22.89% and 24.16%, respectively. Either of the approaches was concluded to be feasible for prediction of moisture content in pine chip flows, but combining the impact and capacitance sensors was easier to implement. In situations where flows could not be impeded, however, the tomographic approach would likely be more useful. PMID:28025536

  14. Acoustic neuroma

    MedlinePlus

    Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor; Hearing loss - acoustic; Tinnitus - acoustic ... Acoustic neuromas have been linked with the genetic disorder neurofibromatosis type 2 (NF2). Acoustic neuromas are uncommon.

  15. DLP/DSP-based optical 3D sensors for the mass market in industrial metrology and life sciences

    NASA Astrophysics Data System (ADS)

    Frankowski, G.; Hainich, R.

    2011-03-01

    GFM has developed and constructed DLP-based optical 3D measuring devices based on structured light illumination. Over the years the devices have been used in industrial metrology and life sciences for different 3D measuring tasks. This lecture will discuss integration of DLP Pico technology and DSP technology from Texas Instruments for mass market optical 3D sensors. In comparison to existing mass market laser triangulation sensors, the new 3D sensors provide a full-field measurement of up to a million points in less than a second. The lecture will further discuss different fields of application and advantages of the new generation of 3D sensors for: OEM application in industrial measuring and inspection; 3D metrology in industry, life sciences and biometrics, and industrial image processing.

  16. Effect of mass loading on ionic polymer metal composite actuators and sensors

    NASA Astrophysics Data System (ADS)

    Sakthi Swarrup, J.; Ganguli, Ranjan

    2015-04-01

    Ionic polymer metal composites (IPMC) actuator for flapping insect scale wing is advantageous due to its low mass, high deflection and simple actuation mechanism. Some of the factors that affect the actuation of IPMC are the amount of hydration in the polymer membrane and the environmental conditions such as temperature, humidity etc. In structural design, the attachment of wing on the IPMC actuators is an important concern as the attached wing increases the mass of actuators thereby affecting the parameters like displacement, stiffness and resonant frequencies. Such IPMC actuators have to produce sufficient actuation force and frequency to lift and flap the attached wing. Therefore, it is relevant to study the influence of attachment of wing on the actuator parameters (displacement, resonant frequency, block force and stiffness) and performance of the actuators. This paper is divided into two parts; the first part deals with the modeling of the IPMC actuators for its effect on the level of water uptake and temperature using energy based method. The modeling method adapted is validated with the experimental procedure used to actuate the IPMC. The second part deals with the experimental analysis of IPMC actuation at dry, wet and in water conditions. The effect of end mass loading on the performance of 20 Hz, high frequency actuator (HFA) and 8.7 Hz, low frequency IPMC actuators (LFA) and sensors is studied. The IPMC actuators are attached with IPMC flapping wing at its free end and performance analysis on the attached wing is also carried out.

  17. A multi-physical model for charge and mass transport in a flexible ionic polymer sensor

    NASA Astrophysics Data System (ADS)

    Zhu, Zicai; Asaka, Kinji; Takagi, Kentaro; Aabloo, Alvo; Horiuchi, Tetsuya

    2016-04-01

    An ionic polymer material can generate electrical potential and function as a bio-sensor under a non-uniform deformation. Ionic polymer-metal composite (IPMC) is a typical flexible ionic polymer sensor material. A multi-physical sensing model is presented at first based on the same physical equations in the physical model for IPMC actuator we obtained before. Under an applied bending deformation, water and cation migrate to the direction of outside electrode immediately. Redistribution of cations causes an electrical potential difference between two electrodes. The cation migration is strongly restrained by the generated electrical potential. And the migrated cations will move back to the inner electrode under the concentration diffusion effect and lead to a relaxation of electrical potential. In the whole sensing process, transport and redistribution of charge and mass are revealed along the thickness direction by numerical analysis. The sensing process is a revised physical process of the actuation, however, the transport properties are quite different from those of the later. And the effective dielectric constant of IPMC, which is related to the morphology of the electrode-ionic polymer interface, is proved to have little relation with the sensing amplitude. All the conclusions are significant for ionic polymer sensing material design.

  18. PDMAA Hydrogel Coated U-Bend Humidity Sensor Suited for Mass-Production

    PubMed Central

    Kelb, Christian; Körner, Martin; Prucker, Oswald; Rühe, Jürgen; Reithmeier, Eduard; Roth, Bernhard

    2017-01-01

    We present a full-polymer respiratory monitoring device suited for application in environments with strong magnetic fields (e.g., during an MRI measurement). The sensor is based on the well-known evanescent field method and consists of a 1 mm plastic optical fiber with a bent region where the cladding is removed and the fiber is coated with poly-dimethylacrylamide (PDMAA). The combination of materials allows for a mass-production of the device by spray-coating and enables integration in disposable medical devices like oxygen masks, which we demonstrate here. We also present results of the application of an autocorrelation-based algorithm for respiratory frequency determination that is relevant for real applications of the device. PMID:28273849

  19. High-resolution, high-linearity temperature sensor using surface acoustic wave device based on LiNbO3/SiO2/Si substrate

    NASA Astrophysics Data System (ADS)

    Tian, Xiang-Guang; Liu, Heng; Tao, Lu-Qi; Yang, Yi; Jiang, Hanjun; Ren, Tian-Ling

    2016-09-01

    A high-resolution and high-linearity surface acoustic wave (SAW) temperature sensor, consisting of a SAW resonator device fabricated on novel X-cut LiNbO3/SiO2/Si piezoelectric substrate and a resonance frequency readout chip using standard 180 nm CMOS technology, is presented for the first time. High temperature performance substrate LiNbO3/SiO2/Si is prepared mainly by ion implantation and wafer bonding at first. RF SAW device with resonance frequency near 900 MHz is designed and fabricated on the substrate. Traditional probe method using network analyzer and the readout chip method are both implemented to characterize the fabricated SAW device. Further measurement of temperature using resonance frequency shift of SAW device demonstrates the feasibility of the combined system as a portable SAW temperature sensor. The obtained frequency-temperature relation of the fabricated device is almost linear. The frequency resolution of the readout chip is 733 Hz and the corresponding temperature accuracy is 0.016 ° C. Resolution of the sensor in this work is superior to most of the commercial temperature measurement sensors. Theory analysis and finite element simulation are also presented to prove the mechanism and validity of using SAW device for temperature detection applications. We conclude that the high-linearity frequency-temperature relation is achieved by the offset between high-order coefficients of LiNbO3 and SiO2 with opposite signs. This work offers the possibility of temperature measuring in ultra-high precision sensing and control applications.

  20. System enhancements of Mesoscale Analysis and Space Sensor (MASS) computer system

    NASA Technical Reports Server (NTRS)

    Hickey, J. S.; Karitani, S.

    1985-01-01

    The interactive information processing for the mesoscale analysis and space sensor (MASS) program is reported. The development and implementation of new spaceborne remote sensing technology to observe and measure atmospheric processes is described. The space measurements and conventional observational data are processed together to gain an improved understanding of the mesoscale structure and dynamical evolution of the atmosphere relative to cloud development and precipitation processes. A Research Computer System consisting of three primary computers was developed (HP-1000F, Perkin-Elmer 3250, and Harris/6) which provides a wide range of capabilities for processing and displaying interactively large volumes of remote sensing data. The development of a MASS data base management and analysis system on the HP-1000F computer and extending these capabilities by integration with the Perkin-Elmer and Harris/6 computers using the MSFC's Apple III microcomputer workstations is described. The objectives are: to design hardware enhancements for computer integration and to provide data conversion and transfer between machines.