Hayden, Todd A.; Holbrook, Christopher M.; Binder, Thomas; Dettmers, John M.; Cooke, Steven J.; Vandergoot, Christopher S.; Krueger, Charles C.
2016-01-01
BackgroundAdvances in acoustic telemetry technology have led to an improved understanding of the spatial ecology of many freshwater and marine fish species. Understanding the performance of acoustic receivers is necessary to distinguish between tagged fish that may have been present but not detected and from those fish that were absent from the area. In this study, two stationary acoustic transmitters were deployed 250 m apart within each of four acoustic receiver lines each containing at least 10 receivers (i.e., eight acoustic transmitters) located in Saginaw Bay and central Lake Huron for nearly 2 years to determine whether the probability of detecting an acoustic transmission varied as a function of time (i.e., season), location, and distance between acoustic transmitter and receiver. Distances between acoustic transmitters and receivers ranged from 200 m to >10 km in each line. The daily observed probability of detecting an acoustic transmission was used in simulation models to estimate the probability of detecting a moving acoustic transmitter on a line of receivers.ResultsThe probability of detecting an acoustic transmitter on a receiver 1000 m away differed by month for different receiver lines in Lake Huron and Saginaw Bay but was similar for paired acoustic transmitters deployed 250 m apart within the same line. Mean probability of detecting an acoustic transmitter at 1000 m calculated over the study period varied among acoustic transmitters 250 m apart within a line and differed among receiver lines in Lake Huron and Saginaw Bay. The simulated probability of detecting a moving acoustic transmitter on a receiver line was characterized by short periods of time with decreased detection. Although increased receiver spacing and higher fish movement rates decreased simulated detection probability, the location of the simulated receiver line in Lake Huron had the strongest effect on simulated detection probability.ConclusionsPerformance of receiver
Field-Deployable Acoustic Digital Systems for Noise Measurement
NASA Technical Reports Server (NTRS)
Shams, Qamar A.; Wright, Kenneth D.; Lunsford, Charles B.; Smith, Charlie D.
2000-01-01
Langley Research Center (LaRC) has for years been a leader in field acoustic array measurement technique. Two field-deployable digital measurement systems have been developed to support acoustic research programs at LaRC. For several years, LaRC has used the Digital Acoustic Measurement System (DAMS) for measuring the acoustic noise levels from rotorcraft and tiltrotor aircraft. Recently, a second system called Remote Acquisition and Storage System (RASS) was developed and deployed for the first time in the field along with DAMS system for the Community Noise Flight Test using the NASA LaRC-757 aircraft during April, 2000. The test was performed at Airborne Airport in Wilmington, OH to validate predicted noise reduction benefits from alternative operational procedures. The test matrix was composed of various combinations of altitude, cutback power, and aircraft weight. The DAMS digitizes the acoustic inputs at the microphone site and can be located up to 2000 feet from the van which houses the acquisition, storage and analysis equipment. Digitized data from up to 10 microphones is recorded on a Jaz disk and is analyzed post-test by microcomputer system. The RASS digitizes and stores acoustic inputs at the microphone site that can be located up to three miles from the base station and can compose a 3 mile by 3 mile array of microphones. 16-bit digitized data from the microphones is stored on removable Jaz disk and is transferred through a high speed array to a very large high speed permanent storage device. Up to 30 microphones can be utilized in the array. System control and monitoring is accomplished via Radio Frequency (RF) link. This paper will present a detailed description of both systems, along with acoustic data analysis from both systems.
Optimizing piezoelectric receivers for acoustic power transfer applications
NASA Astrophysics Data System (ADS)
Gorostiaga, M.; Wapler, M. C.; Wallrabe, U.
2018-07-01
In this paper, we aim to optimize piezoelectric plate receivers for acoustic power transfer applications by analyzing the influence of the losses and of the acoustic boundary conditions. We derive the analytic expressions of the efficiency of the receiver with the optimal electric loads attached, and analyze the maximum efficiency value and its frequency with different loss and acoustic boundary conditions. To validate the analytical expressions that we have derived, we perform experiments in water with composite transducers of different filling fractions, and see that a lower acoustic impedance mismatch can compensate the influence of large dielectric and acoustic losses to achieve a good performance. Finally, we briefly compare the advantages and drawbacks of composite transducers and pure PZT (lead zirconate titanate) plates as acoustic power receivers, and conclude that 1–3 composites can achieve similar efficiency values in low power applications due to their adjustable acoustic impedance.
Optimal Deployment of Sensor Nodes Based on Performance Surface of Underwater Acoustic Communication
Choi, Jee Woong
2017-01-01
The underwater acoustic sensor network (UWASN) is a system that exchanges data between numerous sensor nodes deployed in the sea. The UWASN uses an underwater acoustic communication technique to exchange data. Therefore, it is important to design a robust system that will function even in severely fluctuating underwater communication conditions, along with variations in the ocean environment. In this paper, a new algorithm to find the optimal deployment positions of underwater sensor nodes is proposed. The algorithm uses the communication performance surface, which is a map showing the underwater acoustic communication performance of a targeted area. A virtual force-particle swarm optimization algorithm is then used as an optimization technique to find the optimal deployment positions of the sensor nodes, using the performance surface information to estimate the communication radii of the sensor nodes in each generation. The algorithm is evaluated by comparing simulation results between two different seasons (summer and winter) for an area located off the eastern coast of Korea as the selected targeted area. PMID:29053569
Selby, Thomas H.; Hart, Kristen M.; Fujisaki, Ikuko; Smith, Brian J.; Pollock, Clayton J; Hillis-Star, Zandy M; Lundgren, Ian; Oli, Madan K.
2016-01-01
Submerged passive acoustic technology allows researchers to investigate spatial and temporal movement patterns of many marine and freshwater species. The technology uses receivers to detect and record acoustic transmissions emitted from tags attached to an individual. Acoustic signal strength naturally attenuates over distance, but numerous environmental variables also affect the probability a tag is detected. Knowledge of receiver range is crucial for designing acoustic arrays and analyzing telemetry data. Here, we present a method for testing a relatively large-scale receiver array in a dynamic Caribbean coastal environment intended for long-term monitoring of multiple species. The U.S. Geological Survey and several academic institutions in collaboration with resource management at Buck Island Reef National Monument (BIRNM), off the coast of St. Croix, recently deployed a 52 passive acoustic receiver array. We targeted 19 array-representative receivers for range-testing by submersing fixed delay interval range-testing tags at various distance intervals in each cardinal direction from a receiver for a minimum of an hour. Using a generalized linear mixed model (GLMM), we estimated the probability of detection across the array and assessed the effect of water depth, habitat, wind, temperature, and time of day on the probability of detection. The predicted probability of detection across the entire array at 100 m distance from a receiver was 58.2% (95% CI: 44.0–73.0%) and dropped to 26.0% (95% CI: 11.4–39.3%) 200 m from a receiver indicating a somewhat constrained effective detection range. Detection probability varied across habitat classes with the greatest effective detection range occurring in homogenous sand substrate and the smallest in high rugosity reef. Predicted probability of detection across BIRNM highlights potential gaps in coverage using the current array as well as limitations of passive acoustic technology within a complex coral reef
Acoustic transmitter and receiver performance in freshwater and estuarine environments
We report on the performance of passive acoustic receivers intended to detect the passage of 281 acoustically tagged migratory salmonids in two Oregon coastal watersheds. We found that ambient acoustic noise can vary considerably with location, and that “sync” pulses thought to ...
Constrained Low-Interference Relay Node Deployment for Underwater Acoustic Wireless Sensor Networks
NASA Astrophysics Data System (ADS)
Li, Deying; Li, Zheng; Ma, Wenkai; Chen, Wenping
An Underwater Acoustic Wireless Sensor Network (UA-WSN) consists of many resource-constrained Underwater Sensor Nodes (USNs), which are deployed to perform collaborative monitoring tasks over a given region. One way to preserve network connectivity while guaranteing other network QoS is to deploy some Relay Nodes (RNs) in the networks, in which RNs' function is more powerful than USNs and their cost is more expensive. This paper addresses Constrained Low-interference Relay Node Deployment (C-LRND) problem for 3-D UA-WSNs in which the RNs are placed at a subset of candidate locations to ensure connectivity between the USNs, under both the number of RNs deployed and the value of total incremental interference constraints. We first prove that it is NP-hard, then present a general approximation algorithm framework and get two polynomial time O(1)-approximation algorithms.
Scherrer, Stephen R; Rideout, Brendan P; Giorli, Giacomo; Nosal, Eva-Marie; Weng, Kevin C
2018-01-01
Passive acoustic telemetry using coded transmitter tags and stationary receivers is a popular method for tracking movements of aquatic animals. Understanding the performance of these systems is important in array design and in analysis. Close proximity detection interference (CPDI) is a condition where receivers fail to reliably detect tag transmissions. CPDI generally occurs when the tag and receiver are near one another in acoustically reverberant settings. Here we confirm transmission multipaths reflected off the environment arriving at a receiver with sufficient delay relative to the direct signal cause CPDI. We propose a ray-propagation based model to estimate the arrival of energy via multipaths to predict CPDI occurrence, and we show how deeper deployments are particularly susceptible. A series of experiments were designed to develop and validate our model. Deep (300 m) and shallow (25 m) ranging experiments were conducted using Vemco V13 acoustic tags and VR2-W receivers. Probabilistic modeling of hourly detections was used to estimate the average distance a tag could be detected. A mechanistic model for predicting the arrival time of multipaths was developed using parameters from these experiments to calculate the direct and multipath path lengths. This model was retroactively applied to the previous ranging experiments to validate CPDI observations. Two additional experiments were designed to validate predictions of CPDI with respect to combinations of deployment depth and distance. Playback of recorded tags in a tank environment was used to confirm multipaths arriving after the receiver's blanking interval cause CPDI effects. Analysis of empirical data estimated the average maximum detection radius (AMDR), the farthest distance at which 95% of tag transmissions went undetected by receivers, was between 840 and 846 m for the deep ranging experiment across all factor permutations. From these results, CPDI was estimated within a 276.5 m radius of the
Reconstructing surface wave profiles from reflected acoustic pulses using multiple receivers.
Walstead, Sean P; Deane, Grant B
2014-08-01
Surface wave shapes are determined by analyzing underwater reflected acoustic signals collected at multiple receivers. The transmitted signals are of nominal frequency 300 kHz and are reflected off surface gravity waves that are paddle-generated in a wave tank. An inverse processing algorithm reconstructs 50 surface wave shapes over a length span of 2.10 m. The inverse scheme uses a broadband forward scattering model based on Kirchhoff's diffraction formula to determine wave shapes. The surface reconstruction algorithm is self-starting in that source and receiver geometry and initial estimates of wave shape are determined from the same acoustic signals used in the inverse processing. A high speed camera provides ground-truth measurements of the surface wave field for comparison with the acoustically derived surface waves. Within Fresnel zone regions the statistical confidence of the inversely optimized surface profile exceeds that of the camera profile. Reconstructed surfaces are accurate to a resolution of about a quarter-wavelength of the acoustic pulse only within Fresnel zones associated with each source and receiver pair. Multiple isolated Fresnel zones from multiple receivers extend the spatial extent of accurate surface reconstruction while overlapping Fresnel zones increase confidence in the optimized profiles there.
Throughput Analysis on 3-Dimensional Underwater Acoustic Network with One-Hop Mobile Relay.
Zhong, Xuefeng; Chen, Fangjiong; Fan, Jiasheng; Guan, Quansheng; Ji, Fei; Yu, Hua
2018-01-16
Underwater acoustic communication network (UACN) has been considered as an essential infrastructure for ocean exploitation. Performance analysis of UACN is important in underwater acoustic network deployment and management. In this paper, we analyze the network throughput of three-dimensional randomly deployed transmitter-receiver pairs. Due to the long delay of acoustic channels, complicated networking protocols with heavy signaling overhead may not be appropriate. In this paper, we consider only one-hop or two-hop transmission, to save the signaling cost. That is, we assume the transmitter sends the data packet to the receiver by one-hop direct transmission, or by two-hop transmission via mobile relays. We derive the closed-form formulation of packet delivery rate with respect to the transmission delay and the number of transmitter-receiver pairs. The correctness of the derivation results are verified by computer simulations. Our analysis indicates how to obtain a precise tradeoff between the delay constraint and the network capacity.
Throughput Analysis on 3-Dimensional Underwater Acoustic Network with One-Hop Mobile Relay
Zhong, Xuefeng; Fan, Jiasheng; Guan, Quansheng; Ji, Fei; Yu, Hua
2018-01-01
Underwater acoustic communication network (UACN) has been considered as an essential infrastructure for ocean exploitation. Performance analysis of UACN is important in underwater acoustic network deployment and management. In this paper, we analyze the network throughput of three-dimensional randomly deployed transmitter–receiver pairs. Due to the long delay of acoustic channels, complicated networking protocols with heavy signaling overhead may not be appropriate. In this paper, we consider only one-hop or two-hop transmission, to save the signaling cost. That is, we assume the transmitter sends the data packet to the receiver by one-hop direct transmission, or by two-hop transmission via mobile relays. We derive the closed-form formulation of packet delivery rate with respect to the transmission delay and the number of transmitter–receiver pairs. The correctness of the derivation results are verified by computer simulations. Our analysis indicates how to obtain a precise tradeoff between the delay constraint and the network capacity. PMID:29337911
NASA Astrophysics Data System (ADS)
O'Boyle, Louise; Thorne, Peter; Cooke, Richard; Cohbed Team
2014-05-01
Estuaries are among some of the most important global landscapes in terms of population density, ecology and economy. Understanding the dynamics of these natural mixed sediment environments is of particular interest amid growing concerns over sea level rise, climate variations and estuarine response to these changes. Many predictors exist for bed form formation and sand transport in sandy coastal zones; however less work has been published on mixed sediments. This paper details a field study which forms part of the COHBED project aiming to increase understanding of bed forms in a biotic mixed sediment estuarine environment. The study was carried out in the Dee Estuary, in the eastern Irish Sea between England and Wales from the 21st May to 4th June 2013. A state of the art instrumentation frame, known as SEDbed, was deployed at three sites of differing sediment properties and biological makeup within the intertidal zone of the estuary. The SEDbed deployment consisted of a suite of optical and acoustic instrumentation, including an Acoustic Doppler Velocity Profiler (ADVP), Acoustic Doppler Velocimeter (ADV) and a three dimensional acoustic ripple profiler, 3D-ARP. Supplementary field samples and measurements were recorded alongside the frame during each deployment. This paper focuses on the use of new technological developments for the investigation of sediment dynamics. The hydrodynamics at each of the deployment sites are presented including centimetre resolution velocity profiles in the near bed region of the water column, obtained from the ADVP, which is presently the only autonomous field deployed coherent Doppler profiler . Based on these high resolution profiles variations in frictional velocity, bed shear stress and roughness length are calculated. Comparisons are made with theoretical models and with Reynolds stress values obtained from ADV data at a single point within the ADVP profile and from ADVP data itself. Predictions of bed roughness at each
Receiver bias and the acoustic ecology of aye-ayes (Daubentonia madagascariensis).
Ramsier, Marissa A; Dominy, Nathaniel J
2012-11-01
The aye-aye is a rare lemur from Madagascar that uses its highly specialized middle digit for percussive foraging. This acoustic behavior, also termed tap-scanning, produces dominant frequencies between 6 and 15 kHz. An enhanced auditory sensitivity to these frequencies raises the possibility that the acoustic and auditory specializations of aye-ayes have imposed constraints on the evolution of their vocal signals, especially their primary long-distance vocalization, the screech. Here we explore this concept, termed receiver bias, and suggest that the dominant frequency of the screech call (~2.7 kHz) represents an evolutionary compromise between the opposing adaptive advantages of long-distance sound propagation and enhanced detection by conspecific receivers.
Parsley, Michael J.
2009-01-01
Acoustic transmitters implanted in green sturgeon (Acipenser medirostris) captured in rivers in California were detected by acoustic receivers deployed within and around Baker Bay. The receivers were deployed at eight locations in the Bay and adjacent navigation channels of the Lower Columbia River during a period of anticipated channel dredging. Three of the transmitters detected were confirmed to have been implanted into green sturgeon in previous years; two were from the Sacramento River and one was from the Klamath River. The transmitters (fish) were within detection range of the receivers for only a short period, which is consistent with findings of earlier studies that green sturgeon make rapid and extensive intra-estuary movements.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ploskey, Gene R.; Hughes, James S.; Khan, Fenton
The purpose of this report is to document the results of the acoustic optimization study conducted at John Day Dam during January and February 2008. The goal of the study was to optimize performance of the Juvenile Salmon Acoustic Telemetry System (JSATS) by determining deployment and data acquisition methods to minimize electrical and acoustic interference from various other acoustic sampling devices. Thereby, this would allow concurrent sampling by active and passive acoustic methods during the formal evaluations of the prototype surface flow outlets at the dam during spring and summer outmigration seasons for juvenile salmonids. The objectives for the optimizationmore » study at John Day Dam were to: 1. Design and test prototypes and provide a total needs list of pipes and trolleys to deploy JSATS hydrophones on the forebay face of the powerhouse and spillway. 2. Assess the effect on mean percentage decoded of JSATS transmissions from tags arrayed in the forebay and detected on the hydrophones by comparing: turbine unit OFF vs. ON; spill bay OPEN vs. CLOSED; dual frequency identification sonar (DIDSON) and acoustic Doppler current profiler (ADCP) both OFF vs. ON at a spill bay; and, fixed-aspect hydroacoustic system OFF vs. ON at a turbine unit and a spill bay. 3. Determine the relationship between fixed-aspect hydroacoustic transmit level and mean percentage of JSATS transmissions decoded. The general approach was to use hydrophones to listen for transmissions from JSATS tags deployed in vertical arrays in a series perpendicular to the face of the dam. We used acoustic telemetry equipment manufactured by Technologic and Sonic Concepts. In addition, we assessed old and new JSATS signal detectors and decoders and two different types of hydrophone baffling. The optimization study consisted of a suite of off/on tests. The primary response variable was mean percentage of tag transmissions decoded. We found that there was no appreciable adverse effect on mean
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
Adaptive spread spectrum receiver using acoustic surface wave technology
NASA Astrophysics Data System (ADS)
Das, P.; Milstein, L. B.
1984-05-01
This technical report summarizes the results of the research we have been engaged in regarding the use of surface acoustic wave devices in direct sequence spread spectrum receivers. The heart of this research has been the use of the device as a real-time Fourier transformer. A system of this type is sometimes referred to as a compressive receiver, and our use of the system has been primarily as a means to implement a narrowband interference rejection filter. In addition, we have studied many other topics such as rapid acquisition, Hilbert transform generation, etc. and these topics are all overviewed in this report.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Weiland, Mark A.; Deng, Zhiqun; Seim, Thomas A.
2011-05-26
The U.S. Army Corps of Engineers-Portland District started development of the Juvenile Salmon Acoustic Telemetry System (JSATS), a nonproprietary technology, in 2001 to meet the needs for monitoring the survival of juvenile salmonids through the 31 federal dams in the Federal Columbia River Power System (FCRPS). Initial development focused on coded acoustic microtransmitters, and autonomous receivers that could be deployed in open reaches of the river for detection of the juvenile salmonids implanted with microtransmitters as they passed the autonomous receiver arrays. In 2006 the Pacific Northwest National Laboratory (PNNL) was tasked with development of an acoustic receiver system formore » deployment at hydropower facilities (cabled receiver) for detecting fish tagged with microtransmitters as well as tracking them in 2 or 3-dimensions as the fish passed at the facility for determining route of passage. The additional route of passage information, combined with survival estimates, is used by the dam operators and managers to make structural and operational changes at the hydropower facilities to improve survival of fish as they pass the facilities and through the FCRPS.« less
Weiland, Mark A.; Deng, Z. Daniel; Seim, Tom A.; LaMarche, Brian L.; Choi, Eric Y.; Fu, Tao; Carlson, Thomas J.; Thronas, Aaron I.; Eppard, M. Brad
2011-01-01
In 2001 the U.S. Army Corps of Engineers, Portland District (OR, USA), started developing the Juvenile Salmon Acoustic Telemetry System, a nonproprietary sensing technology, to meet the needs for monitoring the survival of juvenile salmonids through eight large hydroelectric facilities within the Federal Columbia River Power System (FCRPS). Initial development focused on coded acoustic microtransmitters and autonomous receivers that could be deployed in open reaches of the river for detection of the juvenile salmonids implanted with microtransmitters as they passed the autonomous receiver arrays. In 2006, the Pacific Northwest National Laboratory began the development of an acoustic receiver system for deployment at hydropower facilities (cabled receiver) for detecting fish tagged with microtransmitters as well as tracking them in two or three dimensions for determining route of passage and behavior as the fish passed at the facility. The additional information on route of passage, combined with survival estimates, is used by the dam operators and managers to make structural and operational changes at the hydropower facilities to improve survival of fish as they pass the facilities through the FCRPS. PMID:22163918
A MEMS Condenser Microphone-Based Intracochlear Acoustic Receiver.
Pfiffner, Flurin; Prochazka, Lukas; Peus, Dominik; Dobrev, Ivo; Dalbert, Adrian; Sim, Jae Hoon; Kesterke, Rahel; Walraevens, Joris; Harris, Francesca; Roosli, Christof; Obrist, Dominik; Huber, Alexander
2017-10-01
Intracochlear sound pressure (ICSP) measurements are limited by the small dimensions of the human inner ear and the requirements imposed by the liquid medium. A robust intracochlear acoustic receiver (ICAR) for repeated use with a simple data acquisition system that provides the required high sensitivity and small dimensions does not yet exist. The work described in this report aims to fill this gap and presents a new microelectromechanical systems (MEMS) condenser microphone (CMIC)-based ICAR concept suitable for ICSP measurements in human temporal bones. The ICAR head consisted of a passive protective diaphragm (PD) sealing the MEMS CMIC against the liquid medium, enabling insertion into the inner ear. The components of the MEMS CMIC-based ICAR were expressed by a lumped element model (LEM) and compared to the performance of successfully fabricated ICARs. Good agreement was achieved between the LEM and the measurements with different sizes of the PD. The ICSP measurements in a human cadaver temporal bone yielded data in agreement with the literature. Our results confirm that the presented MEMS CMIC-based ICAR is a promising technology for measuring ICSP in human temporal bones in the audible frequency range. A sensor for evaluation of the biomechanical hearing process by quantification of ICSP is presented. The concept has potential as an acoustic receiver in totally implantable cochlear implants.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Shahab, S.; Gray, M.; Erturk, A., E-mail: alper.erturk@me.gatech.edu
2015-03-14
Contactless powering of small electronic components has lately received growing attention for wireless applications in which battery replacement or tethered charging is undesired or simply impossible, and ambient energy harvesting is not a viable solution. As an alternative to well-studied methods of contactless energy transfer, such as the inductive coupling method, the use of ultrasonic waves transmitted and received by piezoelectric devices enables larger power transmission distances, which is critical especially for deep-implanted electronic devices. Moreover, energy transfer by means of acoustic waves is well suited in situations where no electromagnetic fields are allowed. The limited literature of ultrasonic acousticmore » energy transfer is mainly centered on proof-of-concept experiments demonstrating the feasibility of this method, lacking experimentally validated modeling efforts for the resulting multiphysics problem that couples the source and receiver dynamics with domain acoustics. In this work, we present fully coupled analytical, numerical, and experimental multiphysics investigations for ultrasonic acoustic energy transfer from a spherical wave source to a piezoelectric receiver bar that operates in the 33-mode of piezoelectricity. The fluid-loaded piezoelectric receiver under free-free mechanical boundary conditions is shunted to an electrical load for quantifying the electrical power output for a given acoustic source strength of the transmitter. The analytical acoustic-piezoelectric structure interaction modeling framework is validated experimentally, and the effects of system parameters are reported along with optimal electrical loading and frequency conditions of the receiver.« less
Coherent acoustic communication in a tidal estuary with busy shipping traffic.
van Walree, Paul A; Neasham, Jeffrey A; Schrijver, Marco C
2007-12-01
High-rate acoustic communication experiments were conducted in a dynamic estuarine environment. Two current profilers deployed in a shipping lane were interfaced with acoustic modems, which modulated and transmitted the sensor readings every 200 s over a period of four days. QPSK modulation was employed at a raw data rate of 8 kbits on a 12-kHz carrier. Two 16-element hydrophone arrays, one horizontal and one vertical, were deployed near the shore. A multichannel decision-feedback equalizer was used to demodulate the modem signals received on both arrays. Long-term statistical analysis reveals the effects of the tidal cycle, subsea unit location, attenuation by the wake of passing vessels, and high levels of ship-generated noise on the fidelity of the communication links. The use of receiver arrays enables vast improvement in the overall reliability of data delivery compared with a single-receiver system, with performance depending strongly on array orientation. The vertical array offers the best performance overall, although the horizontal array proves more robust against shipping noise. Spatial coherence estimates, variation of array aperture, and inspection of array angular responses point to adaptive beamforming and coherent combining as the chief mechanisms of array gain.
NASA Astrophysics Data System (ADS)
Harne, Ryan L.; Lynd, Danielle T.
2016-08-01
Fixed in spatial distribution, arrays of planar, electromechanical acoustic transducers cannot adapt their wave energy focusing abilities unless each transducer is externally controlled, creating challenges for the implementation and portability of such beamforming systems. Recently, planar, origami-based structural tessellations are found to facilitate great versatility in system function and properties through kinematic folding. In this research we bridge the physics of acoustics and origami-based design to discover that the simple topological reconfigurations of a Miura-ori-based acoustic array yield many orders of magnitude worth of reversible change in wave energy focusing: a potential for acoustic field morphing easily obtained through deployable, tessellated architectures. Our experimental and theoretical studies directly translate the roles of folding the tessellated array to the adaptations in spectral and spatial wave propagation sensitivities for far field energy transmission. It is shown that kinematic folding rules and flat-foldable tessellated arrays collectively provide novel solutions to the long-standing challenges of conventional, electronically-steered acoustic beamformers. While our examples consider sound radiation from the foldable array in air, linear acoustic reciprocity dictates that the findings may inspire new innovations for acoustic receivers, e.g. adaptive sound absorbers and microphone arrays, as well as concepts that include water-borne waves.
System for Manipulating Drops and Bubbles Using Acoustic Radiation Pressure
NASA Technical Reports Server (NTRS)
Oeftering, Richard C. (Inventor)
1999-01-01
The manipulation and control of drops of liquid and gas bubbles is achieved using high intensity acoustics in the form of and/or acoustic radiation pressure and acoustic streaming. generated by a controlled wave emission from a transducer. Acoustic radiation pressure is used to deploy or dispense drops into a liquid or a gas or bubbles into a liquid at zero or near zero velocity from the discharge end of a needle such as a syringe needle. Acoustic streaming is useful in manipulating the drop or bubble during or after deployment. Deployment and discharge is achieved by focusing the acoustic radiation pressure on the discharge end of the needle, and passing the acoustic waves through the fluid in the needle. through the needle will itself, or coaxially through the fluid medium surrounding the needle. Alternatively, the acoustic waves can be counter-deployed by focusing on the discharge end of the needle from a transducer axially aligned with the needle, but at a position opposite the needle, to prevent premature deployment of the drop or bubble. The acoustic radiation pressure can also be used for detecting the presence or absence of a drop or a bubble at the tip of a needle or for sensing various physical characteristics of the drop or bubble such as size or density.
Dudzinski, Kathleen M; Brown, Shani J; Lammers, Marc; Lucke, Klaus; Mann, David A; Simard, Peter; Wall, Carrie C; Rasmussen, Marianne Helene; Magnúsdóttir, Edda Elísabet; Tougaard, Jakob; Eriksen, Nina
2011-01-01
Deployment of any type of measuring device into the ocean, whether to shallow or deeper depths, is accompanied by the hope that this equipment and associated data will be recovered. The ocean is harsh on gear. Salt water corrodes. Currents, tides, surge, storms, and winds collaborate to increase the severity of the conditions that monitoring devices will endure. All ocean-related research has encountered the situations described in this paper. In collating the details of various deployment and recovery scenarios related to stationary passive acoustic monitoring use in the ocean, it is the intent of this paper to share trouble-shooting successes and failures to guide future work with this gear to monitor marine mammal, fish, and ambient (biologic and anthropogenic) sounds in the ocean-in both coastal and open waters.
NASA Technical Reports Server (NTRS)
Fink, Patrick W. (Inventor); Dobbins, Justin A. (Inventor); Lin, Greg Y. (Inventor); Chu, Andrew W. (Inventor); Scully, Robert C. (Inventor)
2006-01-01
A deployable antenna and method for using wherein the deployable antenna comprises a collapsible membrane having at least one radiating element for transmitting electromagnetic waves, receiving electromagnetic waves, or both.
Acoustic telemetry reveals large-scale migration patterns of walleye in Lake Huron
Hayden, Todd A.; Holbrook, Christopher; Fielder, David G.; Vandergoot, Christopher S.; Bergstedt, Roger A.; Dettmers, John M.; Krueger, Charles C.; Cooke, Steven J.
2014-01-01
Fish migration in large freshwater lacustrine systems such as the Laurentian Great Lakes is not well understood. The walleye (Sander vitreus) is an economically and ecologically important native fish species throughout the Great Lakes. In Lake Huron walleye has recently undergone a population expansion as a result of recovery of the primary stock, stemming from changing food web dynamics. During 2011 and 2012, we used acoustic telemetry to document the timing and spatial scale of walleye migration in Lake Huron and Saginaw Bay. Spawning walleye (n = 199) collected from a tributary of Saginaw Bay were implanted with acoustic tags and their migrations were documented using acoustic receivers (n = 140) deployed throughout U.S. nearshore waters of Lake Huron. Three migration pathways were described using multistate mark-recapture models. Models were evaluated using the Akaike Information Criterion. Fish sex did not influence migratory behavior but did affect migration rate and walleye were detected on all acoustic receiver lines. Most (95%) tagged fish migrated downstream from the riverine tagging and release location to Saginaw Bay, and 37% of these fish emigrated from Saginaw Bay into Lake Huron. Remarkably, 8% of walleye that emigrated from Saginaw Bay were detected at the acoustic receiver line located farthest from the release location more than 350 km away. Most (64%) walleye returned to the Saginaw River in 2012, presumably for spawning. Our findings reveal that fish from this stock use virtually the entirety of U.S. nearshore waters of Lake Huron.
Acoustic telemetry reveals large-scale migration patterns of walleye in Lake Huron.
Hayden, Todd A; Holbrook, Christopher M; Fielder, David G; Vandergoot, Christopher S; Bergstedt, Roger A; Dettmers, John M; Krueger, Charles C; Cooke, Steven J
2014-01-01
Fish migration in large freshwater lacustrine systems such as the Laurentian Great Lakes is not well understood. The walleye (Sander vitreus) is an economically and ecologically important native fish species throughout the Great Lakes. In Lake Huron walleye has recently undergone a population expansion as a result of recovery of the primary stock, stemming from changing food web dynamics. During 2011 and 2012, we used acoustic telemetry to document the timing and spatial scale of walleye migration in Lake Huron and Saginaw Bay. Spawning walleye (n = 199) collected from a tributary of Saginaw Bay were implanted with acoustic tags and their migrations were documented using acoustic receivers (n = 140) deployed throughout U.S. nearshore waters of Lake Huron. Three migration pathways were described using multistate mark-recapture models. Models were evaluated using the Akaike Information Criterion. Fish sex did not influence migratory behavior but did affect migration rate and walleye were detected on all acoustic receiver lines. Most (95%) tagged fish migrated downstream from the riverine tagging and release location to Saginaw Bay, and 37% of these fish emigrated from Saginaw Bay into Lake Huron. Remarkably, 8% of walleye that emigrated from Saginaw Bay were detected at the acoustic receiver line located farthest from the release location more than 350 km away. Most (64%) walleye returned to the Saginaw River in 2012, presumably for spawning. Our findings reveal that fish from this stock use virtually the entirety of U.S. nearshore waters of Lake Huron.
Otterå, H; Skilbrei, O T
2016-03-01
The detection rates of stationary acoustic transmitters deployed at three depths on two Atlantic salmon Salmo salar cage farms for c. 2 months were investigated. Deployment depth, time of day, day of the year and specific incidences at the farm substantially affected the rate of signal detection by the receiver. © 2016 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of The Fisheries Society of the British Isles.
NASA Astrophysics Data System (ADS)
Laske, Gabi; Berger, Jon; Orcutt, John; Babcock, Jeff
2014-05-01
We describe an autonomously deployable, communications gateway designed to provide long-term and near real-time data from ocean observatories. The key features of this new system are its abilities to telemeter sensor data from the seafloor to shore without cables or moorings, and to be deployed without a ship, thereby greatly reducing life-cycle costs. The free-floating surface communications gateway utilizes a Liquid Robotics wave glider comprising a surfboard-sized float towed by a tethered, submerged glider, which converts wave motion into thrust. For navigation, the wave glider is equipped with a small computer, a GPS receiver, a rudder, solar panels and batteries, and an Iridium satellite modem. Acoustic communications connect the subsea instruments and the surface gateway while communications between the gateway and land are provided by the Iridium satellite constellation. Wave gliders have demonstrated trans-oceanic range and long-term station keeping capabilities. The acoustics communications package is mounted in a shallow tow body which utilizes a WHOI micro modem and a Benthos low frequency, directional transducer. A matching modem and transducer is mounted on the ocean bottom package. Tests of the surface gateway in 4350 m of water demonstrated an acoustic efficiency of approximately 396 bits/J. For example, it has the ability to send 4 channels of compressed, 1 sample per second data from the ocean bottom to the gateway with an average power draw of approximately 0.15 W and a latency of less than 3 minutes. This gateway is used to send near real-time data from a broadband ocean bottom seismic observatory, first during short week-to-months long test deployments but will ultimately be designed for a two-year operational life. Such data from presently unobserved oceanic areas are critical for both national and international agencies in monitoring and characterizing earthquakes, tsunamis, and nuclear explosions. We present initial results from a two short
Diversity-based acoustic communication with a glider in deep water.
Song, H C; Howe, Bruce M; Brown, Michael G; Andrew, Rex K
2014-03-01
The primary use of underwater gliders is to collect oceanographic data within the water column and periodically relay the data at the surface via a satellite connection. In summer 2006, a Seaglider equipped with an acoustic recording system received transmissions from a broadband acoustic source centered at 75 Hz deployed on the bottom off Kauai, Hawaii, while moving away from the source at ranges up to ∼200 km in deep water and diving up to 1000-m depth. The transmitted signal was an m-sequence that can be treated as a binary-phase shift-keying communication signal. In this letter multiple receptions are exploited (i.e., diversity combining) to demonstrate the feasibility of using the glider as a mobile communication gateway.
Acoustic Scattering Models of Zooplankton and Microstructure
1999-09-30
1998, a remotely operated vehicle was used to deploy acoustic transducers so that the acoustic scattering by siphonophores , a gas-bearing animal, could...their high frequency acoustics systems. 4) In addition, we have identified two types of zooplankton ( siphonophores and pteropods) that have high...Benfield, P.H. Wiebe, and D. Chu, 1999. “In situ measurements of acoustic target strengths of siphonophores ,” Proceedings of the 2nd EAA
DOE Office of Scientific and Technical Information (OSTI.GOV)
Albert, Sarah; Bowman, Daniel; Rodgers, Arthur
Here, this research uses the acoustic coda phase delay method to estimate relative changes in air temperature between explosions with varying event masses and heights of burst. It also places a bound on source–receiver distance for the method. Previous studies used events with different shapes, height of bursts, and masses and recorded the acoustic codas at source–receiver distances less than 1 km. This research further explores the method using explosions that differ in mass (by up to an order of magnitude) and are placed at varying heights. Source–receiver distances also cover an area out to 7 km. Relative air temperaturemore » change estimates are compared to complementary meteorological observations. Results show that two explosions that differ by an order of magnitude cannot be used with this method because their propagation times in the near field and their fundamental frequencies are different. These differences are expressed as inaccuracies in the relative air temperature change estimates. An order of magnitude difference in mass is also shown to bias estimates higher. Small differences in height of burst do not affect the accuracy of the method. Finally, an upper bound of 1 km on source–receiver distance is provided based on the standard deviation characteristics of the estimates.« less
Albert, Sarah; Bowman, Daniel; Rodgers, Arthur; ...
2018-04-23
Here, this research uses the acoustic coda phase delay method to estimate relative changes in air temperature between explosions with varying event masses and heights of burst. It also places a bound on source–receiver distance for the method. Previous studies used events with different shapes, height of bursts, and masses and recorded the acoustic codas at source–receiver distances less than 1 km. This research further explores the method using explosions that differ in mass (by up to an order of magnitude) and are placed at varying heights. Source–receiver distances also cover an area out to 7 km. Relative air temperaturemore » change estimates are compared to complementary meteorological observations. Results show that two explosions that differ by an order of magnitude cannot be used with this method because their propagation times in the near field and their fundamental frequencies are different. These differences are expressed as inaccuracies in the relative air temperature change estimates. An order of magnitude difference in mass is also shown to bias estimates higher. Small differences in height of burst do not affect the accuracy of the method. Finally, an upper bound of 1 km on source–receiver distance is provided based on the standard deviation characteristics of the estimates.« less
Acoustic Telemetry Reveals Large-Scale Migration Patterns of Walleye in Lake Huron
Hayden, Todd A.; Holbrook, Christopher M.; Fielder, David G.; Vandergoot, Christopher S.; Bergstedt, Roger A.; Dettmers, John M.; Krueger, Charles C.; Cooke, Steven J.
2014-01-01
Fish migration in large freshwater lacustrine systems such as the Laurentian Great Lakes is not well understood. The walleye (Sander vitreus) is an economically and ecologically important native fish species throughout the Great Lakes. In Lake Huron walleye has recently undergone a population expansion as a result of recovery of the primary stock, stemming from changing food web dynamics. During 2011 and 2012, we used acoustic telemetry to document the timing and spatial scale of walleye migration in Lake Huron and Saginaw Bay. Spawning walleye (n = 199) collected from a tributary of Saginaw Bay were implanted with acoustic tags and their migrations were documented using acoustic receivers (n = 140) deployed throughout U.S. nearshore waters of Lake Huron. Three migration pathways were described using multistate mark-recapture models. Models were evaluated using the Akaike Information Criterion. Fish sex did not influence migratory behavior but did affect migration rate and walleye were detected on all acoustic receiver lines. Most (95%) tagged fish migrated downstream from the riverine tagging and release location to Saginaw Bay, and 37% of these fish emigrated from Saginaw Bay into Lake Huron. Remarkably, 8% of walleye that emigrated from Saginaw Bay were detected at the acoustic receiver line located farthest from the release location more than 350 km away. Most (64%) walleye returned to the Saginaw River in 2012, presumably for spawning. Our findings reveal that fish from this stock use virtually the entirety of U.S. nearshore waters of Lake Huron. PMID:25506913
A statistical-based approach for acoustic tomography of the atmosphere.
Kolouri, Soheil; Azimi-Sadjadi, Mahmood R; Ziemann, Astrid
2014-01-01
Acoustic travel-time tomography of the atmosphere is a nonlinear inverse problem which attempts to reconstruct temperature and wind velocity fields in the atmospheric surface layer using the dependence of sound speed on temperature and wind velocity fields along the propagation path. This paper presents a statistical-based acoustic travel-time tomography algorithm based on dual state-parameter unscented Kalman filter (UKF) which is capable of reconstructing and tracking, in time, temperature, and wind velocity fields (state variables) as well as the dynamic model parameters within a specified investigation area. An adaptive 3-D spatial-temporal autoregressive model is used to capture the state evolution in the UKF. The observations used in the dual state-parameter UKF process consist of the acoustic time of arrivals measured for every pair of transmitter/receiver nodes deployed in the investigation area. The proposed method is then applied to the data set collected at the Meteorological Observatory Lindenberg, Germany, as part of the STINHO experiment, and the reconstruction results are presented.
ERIC Educational Resources Information Center
Lee, Victoria S.; Zhou, Xiao Ping; Rahn, Douglas A., III; Wang, Emily Q.; Jiang, Jack J.
2008-01-01
Nineteen PD patients who received deep brain stimulation (DBS), 10 non-surgical (control) PD patients, and 11 non-pathologic age- and gender-matched subjects performed sustained vowel phonations. The following acoustic measures were obtained on the sustained vowel phonations: correlation dimension (D[subscript 2]), percent jitter, percent shimmer,…
Australia's continental-scale acoustic tracking database and its automated quality control process
NASA Astrophysics Data System (ADS)
Hoenner, Xavier; Huveneers, Charlie; Steckenreuter, Andre; Simpfendorfer, Colin; Tattersall, Katherine; Jaine, Fabrice; Atkins, Natalia; Babcock, Russ; Brodie, Stephanie; Burgess, Jonathan; Campbell, Hamish; Heupel, Michelle; Pasquer, Benedicte; Proctor, Roger; Taylor, Matthew D.; Udyawer, Vinay; Harcourt, Robert
2018-01-01
Our ability to predict species responses to environmental changes relies on accurate records of animal movement patterns. Continental-scale acoustic telemetry networks are increasingly being established worldwide, producing large volumes of information-rich geospatial data. During the last decade, the Integrated Marine Observing System's Animal Tracking Facility (IMOS ATF) established a permanent array of acoustic receivers around Australia. Simultaneously, IMOS developed a centralised national database to foster collaborative research across the user community and quantify individual behaviour across a broad range of taxa. Here we present the database and quality control procedures developed to collate 49.6 million valid detections from 1891 receiving stations. This dataset consists of detections for 3,777 tags deployed on 117 marine species, with distances travelled ranging from a few to thousands of kilometres. Connectivity between regions was only made possible by the joint contribution of IMOS infrastructure and researcher-funded receivers. This dataset constitutes a valuable resource facilitating meta-analysis of animal movement, distributions, and habitat use, and is important for relating species distribution shifts with environmental covariates.
Counter-narcotic acoustic buoy (CNAB)
NASA Astrophysics Data System (ADS)
Bailey, Mark E.
2004-09-01
As a means to detect drug trafficking in a maritime environment, the Counter Narcotic Acoustic Buoy is part of an inexpensive system designed to detect "Go Fast" boats and report via satellite to a designated location. A go fast boat for this evaluation is defined as any boat with twin 200 horsepower outboard engines. The buoy is designed for deployment in salt water at depths ranging from 50 to 600 feet and can be easily deployed by one or two persons. Detections are based on noise energy exceeding a preset level within a frequency band associated with the go fast boat's acoustic signature. Detection ranges have been demonstrated to greater than three nautical miles.
Oberg, Kevin A.; Duncker, James J.
1999-01-01
In 1998, a prototype 300 kHz, side-looking Acoustic Doppler Current Profiler (ADCP) was deployed in the Chicago Sanitary and Ship Canal (CSSC) at Romeoville, Illinois. Additionally, two upward-looking ADCP's were deployed in the same acoustic path as the side-looking ADCP and in the reach defined by the upstream and downstream acoustic velocity meter (AVM) paths. All three ADCP's were synchronized to the AVM clock at the gaging station so that data were sampled simultaneously. The three ADCP's were deployed for six weeks measuring flow velocities from 0.0 to 2.5 ft/s. Velocities measured by each ADCP were compared to AVM path velocities and to velocities measured by the other ADCP's.
Optimization of an acoustic telemetry array for detecting transmitter-implanted fish
Clements, S.; Jepsen, D.; Karnowski, M.; Schreck, C.B.
2005-01-01
The development of miniature acoustic transmitters and economical, robust automated receivers has enabled researchers to study the movement patterns and survival of teleosts in estuarine and ocean environments, including many species and age-classes that were previously considered too small for implantation. During 2001-2003, we optimized a receiver mooring system to minimize gear and data loss in areas where current action or wave action and acoustic noise are high. In addition, we conducted extensive tests to determine (1) the performance of a transmitter and receiver (Vemco, Ltd.) that are widely used, particularly in North America and Europe and (2) the optimal placement of receivers for recording the passage of fish past a point in a linear-flow environment. Our results suggest that in most locations the mooring system performs well with little loss of data; however, boat traffic remains a concern due to entanglement with the mooring system. We also found that the reception efficiency of the receivers depends largely on the method and location of deployment. In many cases, we observed a range of 0-100% reception efficiency (the percentage of known transmissions that are detected while the receiver is within range of the transmitter) when using a conventional method of mooring. The efficiency was improved by removal of the mounting bar and obstructions from the mooring line. ?? Copyright by the American Fisheries Society 2005.
Method and apparatus of spectro-acoustically enhanced ultrasonic detection for diagnostics
Vo-Dinh, Tuan; Norton, Stephen J.
2001-01-01
An apparatus for detecting a discontinuity in a material includes a source of electromagnetic radiation has a wavelength and an intensity sufficient to induce an enhancement in contrast between a manifestation of an acoustic property in the material and of the acoustic property in the discontinuity, as compared to when the material is not irradiated by the electromagnetic radiation. An acoustic emitter directs acoustic waves to the discontinuity in the material. The acoustic waves have a sensitivity to the acoustic property. An acoustic receiver receives the acoustic waves generated by the acoustic emitter after the acoustic waves have interacted with the material and the discontinuity. The acoustic receiver also generates a signal representative of the acoustic waves received by the acoustic receiver. A processor, in communication with the acoustic receiver and responsive to the signal generated by the acoustic receiver, is programmed to generate informational output about the discontinuity based on the signal generated by the acoustic receiver.
Van Uffelen, Lora J; Nosal, Eva-Marie; Howe, Bruce M; Carter, Glenn S; Worcester, Peter F; Dzieciuch, Matthew A; Heaney, Kevin D; Campbell, Richard L; Cross, Patrick S
2013-10-01
Four acoustic Seagliders were deployed in the Philippine Sea November 2010 to April 2011 in the vicinity of an acoustic tomography array. The gliders recorded over 2000 broadband transmissions at ranges up to 700 km from moored acoustic sources as they transited between mooring sites. The precision of glider positioning at the time of acoustic reception is important to resolve the fundamental ambiguity between position and sound speed. The Seagliders utilized GPS at the surface and a kinematic model below for positioning. The gliders were typically underwater for about 6.4 h, diving to depths of 1000 m and traveling on average 3.6 km during a dive. Measured acoustic arrival peaks were unambiguously associated with predicted ray arrivals. Statistics of travel-time offsets between received arrivals and acoustic predictions were used to estimate range uncertainty. Range (travel time) uncertainty between the source and the glider position from the kinematic model is estimated to be 639 m (426 ms) rms. Least-squares solutions for glider position estimated from acoustically derived ranges from 5 sources differed by 914 m rms from modeled positions, with estimated uncertainty of 106 m rms in horizontal position. Error analysis included 70 ms rms of uncertainty due to oceanic sound-speed variability.
Porter, Chad K; Fitamaurice, Gina; Tribble, David R; Armstrong, Adam W; Mostafa, Manal; Riddle, Mark S
2013-12-01
Though no avian influenza vaccine currently exists, development efforts have increased. Given recent reports of suboptimal vaccination rates among US military personnel, we sought to assess factors associated with a willingness to receive a hypothetical avian influenza vaccine. A self-administered questionnaire was completed by US military personnel during mid-deployment to Iraq, Afghanistan, and surrounding regions. Respondents were predominately male (86.2%), Army (72.1%), and enlisted (86.3%) with a mean age of 29.6 y. The majority (77.1%) agreed to receive an avian influenza vaccine if available. Exploratory factor analysis (EFA) identified two factors, vaccine importance and disease risk, that best described the individual perceptions and both were associated with an increased willingness to receive the hypothetical vaccine (OR: 8.2 and 1.6, respectively). Importantly, after controlling for these factors differences in the willingness to receive this hypothetical vaccine were observed across gender and branch of service. These results indicated that targeted education on vaccine safety and efficacy as well as disease risk may modify vaccination patterns in this population.
Porter, Chad K; Fitamaurice, Gina; Tribble, David R; Armstrong, Adam W; Mostafa, Manal; Riddle, Mark S
2013-01-01
Though no avian influenza vaccine currently exists, development efforts have increased. Given recent reports of suboptimal vaccination rates among US military personnel, we sought to assess factors associated with a willingness to receive a hypothetical avian influenza vaccine. A self-administered questionnaire was completed by US military personnel during mid-deployment to Iraq, Afghanistan, and surrounding regions. Respondents were predominately male (86.2%), Army (72.1%), and enlisted (86.3%) with a mean age of 29.6 y. The majority (77.1%) agreed to receive an avian influenza vaccine if available. Exploratory factor analysis (EFA) identified two factors, vaccine importance and disease risk, that best described the individual perceptions and both were associated with an increased willingness to receive the hypothetical vaccine (OR: 8.2 and 1.6, respectively). Importantly, after controlling for these factors differences in the willingness to receive this hypothetical vaccine were observed across gender and branch of service. These results indicated that targeted education on vaccine safety and efficacy as well as disease risk may modify vaccination patterns in this population. PMID:23917256
Acoustic Metadata Management and Transparent Access to Networked Oceanographic Data Sets
2015-09-30
the deployment that was analyzed. It contains a Start and End time that must lie within the timespan over which the instrument was deployed. A list...encounter – Detections record acoustic encounters. The start time denotes when the animals were first detected acoustically and the end time...systematically. Children of Detection include elements such as the Start and End times of the call, bin, or encounter, a species identifier from the
Localization with a mobile beacon in underwater acoustic sensor networks.
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.
Localization with a Mobile Beacon in Underwater Acoustic Sensor Networks
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. PMID:22778597
Guided acoustic wave inspection system
Chinn, Diane J.
2004-10-05
A system for inspecting a conduit for undesirable characteristics. A transducer system induces guided acoustic waves onto said conduit. The transducer system detects the undesirable characteristics of the conduit by receiving guided acoustic waves that contain information about the undesirable characteristics. The conduit has at least two sides and the transducer system utilizes flexural modes of propagation to provide inspection using access from only the one side of the conduit. Cracking is detected with pulse-echo testing using one transducer to both send and receive the guided acoustic waves. Thinning is detected in through-transmission testing where one transducer sends and another transducer receives the guided acoustic waves.
Large Aperture Acoustic Arrays in Support of Reverberation Studies
1990-04-01
Acoustic Reverberation Special Research Program (SRP). Approach We propose the development of several acoustic arrays in preparation for a FY92 experiment...hydrophone array to measure the directional spectrum of seafloor scattered wavefields. Approach As part of the ONT-sponsored, 1987 SVLA experiment, we...scattered energy. Approach Two methods will be described by which vertical and horizontal acoustic arrays can be deployed together for making bottom
Development of a portable passive-acoustic bedload monitoring system
USDA-ARS?s Scientific Manuscript database
A hydrophone-based passive acoustic bedload-monitoring system was designed, tested and deployed by researchers at the University of Mississippi and the National Sedimentation Laboratory in Oxford, MS. The hydrophone system was designed to be easily deployed and operated by non-experts. In addition, ...
Effects of subsampling of passive acoustic recordings on acoustic metrics.
Thomisch, Karolin; Boebel, Olaf; Zitterbart, Daniel P; Samaran, Flore; Van Parijs, Sofie; Van Opzeeland, Ilse
2015-07-01
Passive acoustic monitoring is an important tool in marine mammal studies. However, logistics and finances frequently constrain the number and servicing schedules of acoustic recorders, requiring a trade-off between deployment periods and sampling continuity, i.e., the implementation of a subsampling scheme. Optimizing such schemes to each project's specific research questions is desirable. This study investigates the impact of subsampling on the accuracy of two common metrics, acoustic presence and call rate, for different vocalization patterns (regimes) of baleen whales: (1) variable vocal activity, (2) vocalizations organized in song bouts, and (3) vocal activity with diel patterns. To this end, above metrics are compared for continuous and subsampled data subject to different sampling strategies, covering duty cycles between 50% and 2%. The results show that a reduction of the duty cycle impacts negatively on the accuracy of both acoustic presence and call rate estimates. For a given duty cycle, frequent short listening periods improve accuracy of daily acoustic presence estimates over few long listening periods. Overall, subsampling effects are most pronounced for low and/or temporally clustered vocal activity. These findings illustrate the importance of informed decisions when applying subsampling strategies to passive acoustic recordings or analyses for a given target species.
NASA Astrophysics Data System (ADS)
Jena, D. P.; Panigrahi, S. N.
2016-03-01
Requirement of designing a sophisticated digital band-pass filter in acoustic based condition monitoring has been eliminated by introducing a passive acoustic filter in the present work. So far, no one has attempted to explore the possibility of implementing passive acoustic filters in acoustic based condition monitoring as a pre-conditioner. In order to enhance the acoustic based condition monitoring, a passive acoustic band-pass filter has been designed and deployed. Towards achieving an efficient band-pass acoustic filter, a generalized design methodology has been proposed to design and optimize the desired acoustic filter using multiple filter components in series. An appropriate objective function has been identified for genetic algorithm (GA) based optimization technique with multiple design constraints. In addition, the sturdiness of the proposed method has been demonstrated in designing a band-pass filter by using an n-branch Quincke tube, a high pass filter and multiple Helmholtz resonators. The performance of the designed acoustic band-pass filter has been shown by investigating the piston-bore defect of a motor-bike using engine noise signature. On the introducing a passive acoustic filter in acoustic based condition monitoring reveals the enhancement in machine learning based fault identification practice significantly. This is also a first attempt of its own kind.
5-Beam ADCP Deployment Strategy Considerations
NASA Astrophysics Data System (ADS)
Moore, T.; Savidge, D. K.; Gargett, A.
2016-02-01
With the increasing availability of 5 beam ADCPs and expanding opportunities for their deployment within both observatory and dedicated process study settings, refinements in deployment strategies are needed.Measuring vertical velocities directly with a vertically oriented acoustic beam requires that the instrument be stably mounted and leveled within fractions of a degree. Leveled shallow water deployments to date have utilized divers to jet pipes into the sand for stability, manually mount the instruments on the pipes, and level them. Leveling has been guided by the deployed instrument's pitch and roll output, available in real-time because of the observatory settings in which the deployments occurred. To expand the range of feasible deployments to deeper, perhaps non-real-time capable settings, alternatives to diver deployment and leveling must be considered. To determine stability requirements, mooring motion (heading, pitch and roll) has been sampled at 1Hz by gimballed ADCPs at a range of instrument deployment depths, and in shrouded and unshrouded cages. Conditions under which ADCP cages resting on the bottom experience significant shifts in tilt, roll or heading are assessed using co-located wind and wave measurements. The accuracy of estimating vertical velocities using all five beams relative to a well leveled vertical single beam is assessed from archived high frequency five beam data, to explore whether easing the leveling requirement is feasible.
Acoustic Imaging of Snowpack Physical Properties
NASA Astrophysics Data System (ADS)
Kinar, N. J.; Pomeroy, J. W.
2011-12-01
Measurements of snowpack depth, density, structure and temperature have often been conducted by the use of snowpits and invasive measurement devices. Previous research has shown that acoustic waves passing through snow are capable of measuring these properties. An experimental observation device (SAS2, System for the Acoustic Sounding of Snow) was used to autonomously send audible sound waves into the top of the snowpack and to receive and process the waves reflected from the interior and bottom of the snowpack. A loudspeaker and microphone array separated by an offset distance was suspended in the air above the surface of the snowpack. Sound waves produced from a loudspeaker as frequency-swept sequences and maximum length sequences were used as source signals. Up to 24 microphones measured the audible signal from the snowpack. The signal-to-noise ratio was compared between sequences in the presence of environmental noise contributed by wind and reflections from vegetation. Beamforming algorithms were used to reject spurious reflections and to compensate for movement of the sensor assembly during the time of data collection. A custom-designed circuit with digital signal processing hardware implemented an inversion algorithm to relate the reflected sound wave data to snowpack physical properties and to create a two-dimensional image of snowpack stratigraphy. The low power consumption circuit was powered by batteries and through WiFi and Bluetooth interfaces enabled the display of processed data on a mobile device. Acoustic observations were logged to an SD card after each measurement. The SAS2 system was deployed at remote field locations in the Rocky Mountains of Alberta, Canada. Acoustic snow properties data was compared with data collected from gravimetric sampling, thermocouple arrays, radiometers and snowpit observations of density, stratigraphy and crystal structure. Aspects for further research and limitations of the acoustic sensing system are also discussed.
Acoustic Seaglider: PhilSea10 Data Analysis
2016-06-13
and (simple) Kalman filtering techniques will be explored to utilize the unique time-space sound speed sampling of the Seagliders to generate snapshots... temperature and salinity were deployed (Figure 1). General objectives of the experiment are to understand the acoustic propagation in the...an acoustic recording system (ARS) to record the moored source transmissions, as well as temperature , salinity and pressure sensors (from which
Coronado National Monument : acoustical monitoring 2010
DOT National Transportation Integrated Search
2014-04-01
During the summer (September October) of 2010, Volpe Center personnel deployed acoustic measurement system at Fort Bowie National Historic Site (FOBO) for approximately one month. The baseline data collected during this period will help park mana...
Petroglyph National Monument : acoustical monitoring 2010
DOT National Transportation Integrated Search
2013-01-01
During the summer of 2010 (August September), the Volpe Center collected baseline acoustical data at Petroglyph National Monument (PETR) at two sites deployed for approximately 30 days each. The baseline data collected during this period will hel...
Smith, Richard W.
1979-01-01
An acoustic imaging system for displaying an object viewed by a moving array of transducers as the array is pivoted about a fixed point within a given plane. A plurality of transducers are fixedly positioned and equally spaced within a laterally extending array and operatively directed to transmit and receive acoustic signals along substantially parallel transmission paths. The transducers are sequentially activated along the array to transmit and receive acoustic signals according to a preestablished sequence. Means are provided for generating output voltages for each reception of an acoustic signal, corresponding to the coordinate position of the object viewed as the array is pivoted. Receptions from each of the transducers are presented on the same display at coordinates corresponding to the actual position of the object viewed to form a plane view of the object scanned.
Ocean Variability Effects on Underwater Acoustic Communications
2007-09-30
sea surface was rougher. To recover the transmitted symbols which have been passed through the time-varying multi-path acoustic channels, a new ...B is about 6 dB higher than that during enviromental case A. Due to the large aperture and deployment range of the MPL array, the channel impulse...environmental fluctuations and the performance of coherent underwater acoustic communications presents new insights into the operational effectiveness of
Wupatki National Monument : Acoustical Monitoring 2010
DOT National Transportation Integrated Search
2013-05-01
During the summer of 2010 (July - August), the Volpe Center collected baseline acoustical data at Wupatki National Monument (WUPA) at two sites deployed for approximately 30 days at each site. The baseline data collected during this period will help ...
Tuzigoot National Monument: Acoustical Monitoring 2010
DOT National Transportation Integrated Search
2013-05-01
During the summer of 2010 (July-August), the Volpe Center collected baseline acoustical data at Tuzigoot National Monument (TUZI) at a site deployed for approximately 30 days. The baseline data collected during this period will help park managers and...
NASA Astrophysics Data System (ADS)
Matoza, R. S.; Jolly, A. D.; Fee, D.; Johnson, R.; Kilgour, G.; Christenson, B. W.; Garaebiti, E.; Iezzi, A. M.; Austin, A.; Kennedy, B.; Fitzgerald, R.; Key, N.
2016-12-01
Seismo-acoustic wavefields at volcanoes contain rich information on shallow magma transport and subaerial eruption processes. Acoustic wavefields from eruptions are predicted to be directional, but sampling this wavefield directivity is challenging because infrasound sensors are usually deployed on the ground surface. We attempt to overcome this observational limitation using a novel deployment of infrasound sensors on tethered balloons in tandem with a suite of dense ground-based seismo-acoustic, geochemical, and eruption imaging instrumentation. We present preliminary results from a field experiment at Yasur Volcano, Vanuatu from July 26th to August 4th 2016. Our observations include data from a temporary network of 11 broadband seismometers, 6 single infrasonic microphones, 7 small-aperture 3-element infrasound arrays, 2 infrasound sensor packages on tethered balloons, an FTIR, a FLIR, 2 scanning Flyspecs, and various visual imaging data. An introduction to the dataset and preliminary analysis of the 3D seismo-acoustic wavefield and source process will be presented. This unprecedented dataset should provide a unique window into processes operating in the shallow magma plumbing system and their relation to subaerial eruption dynamics.
Ocean acoustic reverberation tomography.
Dunn, Robert A
2015-12-01
Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., <10 km), the acoustic wave field densely samples properties of the water column over the width of the receiver array. A method, referred to as ocean acoustic reverberation tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography.
Tumacacori National Historic Park : acoustical monitoring 2010
DOT National Transportation Integrated Search
2014-11-01
During September 2010, Volpe Center personnel deployed two acoustic measurement sites at Tumaccori National Historical Park (TUMA) for approximately 30 days each. The baseline data collected during this period will help park managers and planners e...
Fort Bowie National Historic Site : acoustical monitoring
DOT National Transportation Integrated Search
2014-04-01
During the summer (September October) of 2010, Volpe Center personnel deployed acoustic measurement system at Fort Bowie National Historic Site (FOBO) for approximately one month. The baseline data collected during this period will help park mana...
Performance of an autonomously deployable telemetered deep ocean seismic observatory
NASA Astrophysics Data System (ADS)
Berger, Jonathan; Laske, Gabe; Orcutt, John; Babcock, Jeffrey
2016-04-01
We describe a transformative technology that can provide near real-time telemetry of sensor data from the ocean bottom without a moored buoy or a cable to shore. The breakthrough technology that makes this system possible is an autonomous surface vehicle called a Wave Glider developed by Liquid Robotics, which harvests wave and solar energy for motive and electrical power. For navigation, the wave glider is equipped with a small computer, a GPS receiver, a rudder, solar panels and batteries, AIS ship detection receiver, weather station, and an Iridium satellite modem. Wave gliders have demonstrated trans-oceanic range and long-term station keeping capabilities. We present results from several deployments of a prototype system that demonstrate the feasibility of this concept. The system comprises ocean bottom package (OBP) and an ocean surface gateway (OSG). Acoustic communications connect the OBP instruments with OSG while communications between the gateway and land are provided by the Iridium satellite constellation. The most recent deployment of the OBP was off the edge of the Patton Escarpment some 300 km west of San Diego in 4000 m of water. The OSG was launched about 30 km west of San Diego harbor and programmed to navigate to the site of the ocean bottom package. Arriving after 161 hours, the OSG then commenced holding station at the site for the next 68 days. Speeds over-the-ground varied with wind, wave, and surface current conditions but averaged 0.5 m/s while winds varied between 0 m/s and 17 m/s and wave heights between 0.2 m and 5.9 m. Over this period the median total data latency was 260 s and the data loss less that 0.2% when the wave glider was within 1.5 km of the central point. We have also tested a full-scale model of a towable ocean bottom package, which demonstrated that a wave glider could tow and navigate an autonomously deployable ocean bottom package. Taken together, these tests have demonstrated that the concept is viable for long
Pecos National Historic Park : acoustical monitoring 2010
DOT National Transportation Integrated Search
2013-03-01
During the summer of 2010 (August September), the Volpe Center collected baseline acoustical data at Pecos National Historical Park (PECO) at four sites deployed for approximately 30 days each. The baseline data collected during this period will ...
Wright Brothers National Memorial : acoustical monitoring 2011
DOT National Transportation Integrated Search
2014-11-01
During the winter of 2011(September - November) baseline acoustical data were collected at Wright Brothers National Memorial (WRBR) at two sites deployed for approximately 30 days each. The baseline data collected during these periods will help park ...
NASA Astrophysics Data System (ADS)
Zampolli, Mario; Haralabus, Georgios; Prior, Mark K.; Heaney, Kevin D.; Campbell, Richard
2014-05-01
Hydrophone stations of the Comprehensive Nuclear-Test-Ban Organisation (CTBTO) International Monitoring System (IMS), with the exception of one in Australia, comprise two triplets of submerged moored hydrophones, one North and one South of the island from which the respective system is deployed. Triplet distances vary approximately between 50 - 100 km from the island, with each triplet connected to the receiving shore equipment by fibre-optic submarine data cables. Once deployed, the systems relay underwater acoustic waveforms in the band 1 - 100 Hz in real time to Vienna via a shore based satellite link. The design life of hydroacoustic stations is at least 20 years, without need for any maintenance of the underwater system. The re-establishment of hydrophone monitoring station HA04 at Crozet (French Southern and Antarctic Territories) in the South-Western Indian Ocean is currently being investigated. In order to determine appropriate locations and depths for the installation of the hydrophones a number of constraints need to be taken into account and balanced against each other. The most important of these are (i) hydrophone depth in a region where the sound-speed profile is mostly upward refracting and the Sound Fixing and Ranging (SOFAR) channel is not well defined, (ii) a safe distance from the surface currents which occupy the first few hundred meters of the water column, (iii) seabed slopes that enable the safe deployment of the hydrophone mooring bases, (iv) avoidance of regions of high internal tide activity, (v) choice of locations to optimize basin and cross-basin scale acoustic coverage of each triplet and (vi) redundancy considerations so that one triplet can partially cover for the other one in case of necessity. A state-of-the-art three-dimensional (3-D) parabolic equation acoustic propagation model was used to model the propagation for a number of potential triplet locations. Criteria for short-listing candidate triplet locations were based on
Ferguson, B G
1993-12-01
The acoustic emissions from a propeller-driven aircraft are received by a microphone mounted just above ground level and then by a hydrophone located below the sea surface. The dominant feature in the output spectrum of each acoustic sensor is the spectral line corresponding to the propeller blade rate. A frequency estimation technique is applied to the acoustic data from each sensor so that the Doppler shift in the blade rate can be observed at short time intervals during the aircraft's transit overhead. For each acoustic sensor, the observed variation with time of the Doppler-shifted blade rate is compared with the variation predicted by a simple ray-theory model that assumes the atmosphere and the sea are distinct isospeed sound propagation media separated by a plane boundary. The results of the comparison are shown for an aircraft flying with a speed of about 250 kn at altitudes of 500, 700, and 1000 ft.
Fort Davis National Historic Site : acoustical monitoring
DOT National Transportation Integrated Search
2013-06-01
During the summer of 2010 (September - October 2010), the Volpe Center collected baseline acoustical data at Fort Davis National Historic Site (FODA)at two sites deployed for approximately 30 days each. The baseline data collected during this period ...
Walnut Canyon National Monument : Acoustical Monitoring 2010
DOT National Transportation Integrated Search
2013-06-01
During the summer of 2010 (July - August), the Volpe Center collected baseline acoustical data at Walnut Canyon National Monument (WACA) at a site deployed for approximately 30 days. The baseline data collected during this period will help park manag...
Big Bend National Park: Acoustical Monitoring 2010
DOT National Transportation Integrated Search
2013-06-01
During the summer of 2010 (September October 2010), the Volpe Center collected baseline acoustical data at Big Bend National Park (BIBE) at four sites deployed for approximately 30 days each. The baseline data collected during this period will he...
Montezuma Castle National Monument : acoustical monitoring 2010
DOT National Transportation Integrated Search
2013-03-01
During the summer of 2010 (July-August), the Volpe Center collected baseline acoustical data at Montezuma Castle National Monument (MOCA) at two sites deployed for approximately 30 days each. The baseline data collected during this period will help p...
Speaker verification system using acoustic data and non-acoustic data
Gable, Todd J [Walnut Creek, CA; Ng, Lawrence C [Danville, CA; Holzrichter, John F [Berkeley, CA; Burnett, Greg C [Livermore, CA
2006-03-21
A method and system for speech characterization. One embodiment includes a method for speaker verification which includes collecting data from a speaker, wherein the data comprises acoustic data and non-acoustic data. The data is used to generate a template that includes a first set of "template" parameters. The method further includes receiving a real-time identity claim from a claimant, and using acoustic data and non-acoustic data from the identity claim to generate a second set of parameters. The method further includes comparing the first set of parameters to the set of parameters to determine whether the claimant is the speaker. The first set of parameters and the second set of parameters include at least one purely non-acoustic parameter, including a non-acoustic glottal shape parameter derived from averaging multiple glottal cycle waveforms.
A new, simple electrostatic-acoustic hybrid levitator
NASA Technical Reports Server (NTRS)
Lierke, E. G.; Loeb, H.; Gross, D.
1990-01-01
Battelle has developed a hybrid levitator by combining the known single-axis acoustic standing wave levitator with a coaxial DC electric field. The resulting Coulomb forces on the charged liquid or solid sample support its weight and, together with the acoustic force, center the sample. Liquid samples with volumes approximately less than 100 micro-liters are deployed from a syringe reservoir into the acoustic pressure node. The sample is charged using a miniature high voltage power supply (approximately less than 20 kV) connected to the syringe needle. As the electric field, generated by a second miniature power supply, is increased, the acoustic intensity is reduced. The combination of both fields allows stable levitation of samples larger than either single technique could position on the ground. Decreasing the acoustic intensity reduces acoustic convection and sample deformation. Neither the electrostatic nor the acoustic field requires sample position sensing or active control. The levitator, now used for static and dynamic fluid physics investigations on the ground, can be easily modified for space operations.
ALFA MHK Biological Monitoring Stationary deployment
Horne, John
2016-10-01
Acoustic backscatter data from a WBAT operating at 70kHz deployed at PMEC-SETS from April to September of 2016. 180 pings were collected at 1Hz every two hours, as part of the Advanced Laboratory and Field Arrays (ALFA) for Marine Energy project. Data was subject to preliminary processing (noise removal, a threshold of -75dB was applied, surface turbulence and data below 0.5m from the bottom was removed).
System and method for sonic wave measurements using an acoustic beam source
Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian
2015-08-11
A method and system for investigating structure near a borehole are described herein. The method includes generating an acoustic beam by an acoustic source; directing at one or more azimuthal angles the acoustic beam towards a selected location in a vicinity of a borehole; receiving at one or more receivers an acoustic signal, the acoustic signal originating from a reflection or a refraction of the acoustic wave by a material at the selected location; and analyzing the received acoustic signal to characterize features of the material around the borehole.
Acoustic source signal and directivity for explosive sources in complex environments
NASA Astrophysics Data System (ADS)
Waxler, R.; Bonner, J. L.; Reinke, R.; Talmadge, C. L.; Kleinert, D. E.; Alberts, W.; Lennox, E.
2012-12-01
Much work has gone into characterizing the blast wave, and ultimate acoustic pulse, produced by an explosion in flat, open land. Recently, an experiment was performed to study signals produced by explosions in more complex environments, both above and below ground. Explosive charges, ranging in weight from 200 to 2000 lbs., were detonated in a variety of configurations in and around tubes and culverts as well as buried in alluvium and limestone. A large number of acoustic sensors were deployed to capture the signals from the explosions. The deployment included two concentric rings of eighteen sensors each, spaced roughly every twenty degrees at radii of 300 and 1000 meters and surrounding the explosions. These captured the acoustic source function and directivity. In addition, a network of sensors, including sensors mounted on an aerostat and elevated to 300 meters altitude, were deployed throughout the area to capture the signals as they propagated. The meteorological state was monitored with a variety of instruments including a tethersonde, radiosonde and sodar. Significant directivity was observed in the signals from many of the shots, including those from charges that were detonated underground, but not near any structure. Results from the experiment will be presented.
Petroglyph National Monument : acoustical monitoring 2010 and 2012
DOT National Transportation Integrated Search
2014-03-01
During the summer of 2010 (August September) and winter of 2012 (February April), baseline acoustical data were collected at Petroglyph National Monument (PETR) at two sites deployed for approximately 30 days each. The baseline data collected...
Acoustic Location of Lightning Using Interferometric Techniques
NASA Astrophysics Data System (ADS)
Erives, H.; Arechiga, R. O.; Stock, M.; Lapierre, J. L.; Edens, H. E.; Stringer, A.; Rison, W.; Thomas, R. J.
2013-12-01
Acoustic arrays have been used to accurately locate thunder sources in lightning flashes. The acoustic arrays located around the Magdalena mountains of central New Mexico produce locations which compare quite well with source locations provided by the New Mexico Tech Lightning Mapping Array. These arrays utilize 3 outer microphones surrounding a 4th microphone located at the center, The location is computed by band-passing the signal to remove noise, and then computing the cross correlating the outer 3 microphones with respect the center reference microphone. While this method works very well, it works best on signals with high signal to noise ratios; weaker signals are not as well located. Therefore, methods are being explored to improve the location accuracy and detection efficiency of the acoustic location systems. The signal received by acoustic arrays is strikingly similar to th signal received by radio frequency interferometers. Both acoustic location systems and radio frequency interferometers make coherent measurements of a signal arriving at a number of closely spaced antennas. And both acoustic and interferometric systems then correlate these signals between pairs of receivers to determine the direction to the source of the received signal. The primary difference between the two systems is the velocity of propagation of the emission, which is much slower for sound. Therefore, the same frequency based techniques that have been used quite successfully with radio interferometers should be applicable to acoustic based measurements as well. The results presented here are comparisons between the location results obtained with current cross correlation method and techniques developed for radio frequency interferometers applied to acoustic signals. The data were obtained during the summer 2013 storm season using multiple arrays sensitive to both infrasonic frequency and audio frequency acoustic emissions from lightning. Preliminary results show that
Acoustic velocity measurements in materials using a regenerative method
Laine, Edwin F.
1986-01-01
Acoustic energy is propagated through earth material between an electro-acoustic generator and a receiver which converts the received acoustic energy into electrical signals. A closed loop is formed by a variable gain amplifier system connected between the receiver and the generator. The gain of the amplifier system is increased until sustained oscillations are produced in the closed loop. The frequency of the oscillations is measured as an indication of the acoustic propagation velocity through the earth material. The amplifier gain is measured as an indication of the acoustic attenuation through the earth materials. The method is also applicable to the non-destructive testing of structural materials, such as steel, aluminum and concrete.
Acoustic-velocity measurements in materials using a regenerative method
Laine, E.F.
1982-09-30
Acoustic energy is propatated through earth material between an electro-acoustic generator and a receiver which converts the received acoustic energy into electrical signals. A closed loop is formed by a variable gain amplifier system connected between the receiver and the generator. The gain of the amplifier system is increased until sustained oscillations are produced in the closed loop. The frequency of the oscillations is measured as an indication of the acoustic propagation velocity through the earth material. The amplifier gain is measured as an indication of the acoustic attenuation through the earth materials. The method is also applicable to the non-destructive testing of structural materials, such as steel, aluminum and concrete.
Ocean Acoustic Tomography Mooring Design Study.
1982-04-01
mounted in RP. - RP contains its own power source. - Dead -weight anchor. - Acoustic Release is located in the RP. Configurations 1. - Top buoyancy...float is a steel sphere. icI - USS 3 x 19 jacketed wire rope is used as the tension member. - Anchor is dead -weight. - Acoustic Release is located...Receiver/Satellite Telemetry Moorings (RT) - Receiver depth 1000 - 3500 m. - Ocean depth is 5000 m. - Receiver contains its own power source. - Dead
Passive wake acoustics measurements at Denver International Airport
DOT National Transportation Integrated Search
2004-04-26
From August to September 2003, NASA conducted an extensive measurement campaign to characterize the acoustic signal of wake vortices. A large, both spatially as well as in number of elements, phased microphone array was deployed at Denver Internation...
Mount Rainier National Park : acoustical monitoring Report 2009
DOT National Transportation Integrated Search
2011-09-01
During the summer (July September 2009), baseline acoustical data were collected for approximately one month at two sites deployed by NPS personnel in Mount Rainier National Park (MORA). The purpose of the monitoring effort was to supplement prio...
Kings Mountain National Military Park : acoustical monitoring 2012
DOT National Transportation Integrated Search
2014-11-01
During the winter of 2012(November-December) baseline acoustical data were collected at Kings Mountain National Military Park (KIMO)at two sites deployed for approximately 30 days each. The baseline data collected during these periods will help park ...
Nondestructive acoustic electric field probe apparatus and method
Migliori, Albert
1982-01-01
The disclosure relates to a nondestructive acoustic electric field probe and its method of use. A source of acoustic pulses of arbitrary but selected shape is placed in an oil bath along with material to be tested across which a voltage is disposed and means for receiving acoustic pulses after they have passed through the material. The received pulses are compared with voltage changes across the material occurring while acoustic pulses pass through it and analysis is made thereof to determine preselected characteristics of the material.
Sunset Crater Volcano National Monument : Acoustical Monitoring 2010
DOT National Transportation Integrated Search
2013-05-01
During the summer of 2010 (July - August), the Volpe Center collected baseline acoustical data at Sunset Crater Volcano National Monument (SUCR) at a site deployed for approximately 30 days. The baseline data collected during this period will help pa...
Tuzigoot National Monument : acoustical monitoring 2010 and 2012
DOT National Transportation Integrated Search
2014-03-01
During the summer of 2010 (July - August) and winter of 2012 (March-April) baseline acoustical data were collected at Tuzigoot National Monument (TUZI) at a site deployed for approximately 30 days during each period. The baseline data collected durin...
Detection of impulsive sources from an aerostat-based acoustic array data collection system
NASA Astrophysics Data System (ADS)
Prather, Wayne E.; Clark, Robert C.; Strickland, Joshua; Frazier, Wm. Garth; Singleton, Jere
2009-05-01
An aerostat based acoustic array data collection system was deployed at the NATO TG-53 "Acoustic Detection of Weapon Firing" Joint Field Experiment conducted in Bourges, France during the final two weeks of June 2008. A variety of impulsive sources including mortar, artillery, gunfire, RPG, and explosive devices were fired during the test. Results from the aerostat acoustic array will be presented against the entire range of sources.
2016-12-22
in both the energy received and the travel time , both exhibiting strong 3D propagation. A paper was published on using noise correlations to estimate...3-5 Hz. 3.2. Passive Acoustic Thermometry From theoretical considerations it follows that the acoustic travel time between two sensors can be...obtained from the ambient noise field. In underwater acoustics, this travel time strongly depends on the depth and temperature and to a lesser extent
Acoustic properties of humpback whale songs.
Au, Whitlow W L; Pack, Adam A; Lammers, Marc O; Herman, Louis M; Deakos, Mark H; Andrews, Kim
2006-08-01
A vertical array of five hydrophones was used to measure the acoustic field in the vertical plane of singing humpback whales. Once a singer was located, two swimmers with snorkel gear were deployed to determine the orientation of the whale and position the boat so that the array could be deployed in front of the whale at a minimum standoff distance of at least 10 m. The spacing of the hydrophones was 7 m with the deepest hydrophone deployed at a depth of 35 m. An eight-channel TASCAM recorder with a bandwidth of 24 kHz was used to record the hydrophone signals. The location (distance and depth) of the singer was determined by computing the time of arrival differences between the hydrophone signals. The maximum source level varied between individual units in a song, with values between 151 and 173 dB re 1 microPa. One of the purposes of this study was to estimate potential sound exposure of nearby conspecifics. The acoustic field determined by considering the relative intensity of higher frequency harmonics in the signals indicated that the sounds are projected in the horizontal direction despite the singer being canted head downward anywhere from about 25 degrees to 90 degrees. High-frequency harmonics extended beyond 24 kHz, suggesting that humpback whales may have an upper frequency limit of hearing as high as 24 kHz.
Acoustic reciprocity: An extension to spherical harmonics domain.
Samarasinghe, Prasanga; Abhayapala, Thushara D; Kellermann, Walter
2017-10-01
Acoustic reciprocity is a fundamental property of acoustic wavefields that is commonly used to simplify the measurement process of many practical applications. Traditionally, the reciprocity theorem is defined between a monopole point source and a point receiver. Intuitively, it must apply to more complex transducers than monopoles. In this paper, the authors formulate the acoustic reciprocity theory in the spherical harmonics domain for directional sources and directional receivers with higher order directivity patterns.
Measurement of acoustic attenuation in South Pole ice
NASA Astrophysics Data System (ADS)
IceCube Collaboration; Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bissok, M.; Blaufuss, E.; Boersma, D. J.; Bohm, C.; Böser, S.; Botner, O.; Bradley, L.; Braun, J.; Buitink, S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; de Clercq, C.; Demirörs, L.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; Deyoung, T.; Díaz-Vélez, J. C.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Feusels, T.; Filimonov, K.; Finley, C.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Ganugapati, R.; Geisler, M.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gunasingha, R. M.; Gurtner, M.; Gustafsson, L.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Imlay, R. L.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kemming, N.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Knops, S.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kuehn, K.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Lauer, R.; Lehmann, R.; Lennarz, D.; Lünemann, J.; Madsen, J.; Majumdar, P.; Maruyama, R.; Mase, K.; Matis, H. S.; Matusik, M.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; Ono, M.; Panknin, S.; Paul, L.; Pérez de Los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Roucelle, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Sarkar, S.; Schatto, K.; Schlenstedt, S.; Schmidt, T.; Schneider, D.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sullivan, G. W.; Swillens, Q.; Taboada, I.; Tamburro, A.; Tarasova, O.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; van Santen, J.; Voigt, B.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; IceCube Collaboration
2011-01-01
Using the South Pole Acoustic Test Setup (SPATS) and a retrievable transmitter deployed in holes drilled for the IceCube experiment, we have measured the attenuation of acoustic signals by South Pole ice at depths between 190 m and 500 m. Three data sets, using different acoustic sources, have been analyzed and give consistent results. The method with the smallest systematic uncertainties yields an amplitude attenuation coefficient α = 3.20 ± 0.57 km-1 between 10 and 30 kHz, considerably larger than previous theoretical estimates. Expressed as an attenuation length, the analyses give a consistent result for λ ≡ 1/α of ˜300 m with 20% uncertainty. No significant depth or frequency dependence has been found.
Acoustic cymbal performance under hydrostatic pressure
NASA Astrophysics Data System (ADS)
Jenne, Kirk E.; Huang, Dehua; Howarth, Thomas R.
2004-05-01
Continual awareness about the need to develop light-weight, low-volume, broadband, underwater acoustic projector and receive arrays that perform consistently in diverse environments is evident in recent Navy acoustic system initiatives. Acoustic cymbals, so named for resemblance to the percussive musical instruments, are miniature flextensional transducers that may perhaps meet the performance criteria for consistent performance under hydrostatic pressure after modifications in the design. These acoustic cymbals consist of a piezoceramic disk (or ring) bonded to two opposing cymbal-shaped metal shells. Operating as mechanical transformers, the two metal shells convert the large generative force inherently within the disk's radial mode into increased volume displacement at the metal shell surface to obtain volume displacement that translates into usable source levels and/or sensitivities at sonar frequencies in a relatively broad band. The air-backed design for standard acoustic cymbal transducers presents a barrier to deepwater applications. A new acoustic cymbal design for high-pressure applications will be presented for the first time. This practical pressure compensation is designed to diminish the effects of hydrostatic pressure to maintain consistent acoustic cymbal performance. Transmit and receive performance data, determined at the Naval Undersea Warfare Center's (NUWC) Acoustic Pressure Tank Facility (APTF), is presented.
Effects of atmospheric variations on acoustic system performance
NASA Technical Reports Server (NTRS)
Nation, Robert; Lang, Stephen; Olsen, Robert; Chintawongvanich, Prasan
1993-01-01
Acoustic propagation over medium to long ranges in the atmosphere is subject to many complex, interacting effects. Of particular interest at this point is modeling low frequency (less than 500 Hz) propagation for the purpose of predicting ranges and bearing accuracies at which acoustic sources can be detected. A simple means of estimating how much of the received signal power propagated directly from the source to the receiver and how much was received by turbulent scattering was developed. The correlations between the propagation mechanism and detection thresholds, beamformer bearing estimation accuracies, and beamformer processing gain of passive acoustic signal detection systems were explored.
Cape Hatteras National Seashore acoustical monitoring 2008 and 2011
DOT National Transportation Integrated Search
2014-11-01
During the summer of 2008(May) and winter of 2011 (September-November) baseline acoustical data were collected at Cape Hatteras National Seashore at three sites deployed for approximately 30 days each. The baseline data collected during these periods...
Montezuma Castle National Monument : acoustical monitoring 2010 and 2012
DOT National Transportation Integrated Search
2014-03-01
During the summer of 2010 (July-August)and winter of 2012 (March-May) baseline acoustical data were collected at Montezuma Castle National Monument (MOCA), at two sites deployed for approximately 30 days each. The baseline data collected during these...
Rio Grande Wild and Scenic River : Acoustical Monitoring 2010
DOT National Transportation Integrated Search
2013-06-01
During the summer of 2010 (September October 2010), the Volpe Center collected baseline acoustical data at Rio Grande Wild and Scenic River (RIGR) at three sites deployed for approximately 30 days each. The baseline data collected during this per...
Measurements of humpback whale song sound levels received by a calf in association with a singer.
Chen, Jessica; Pack, Adam A; Au, Whitlow W L; Stimpert, Alison K
2016-11-01
Male humpback whales produce loud "songs" on the wintering grounds and some sing while escorting mother-calf pairs, exposing them to near-continuous sounds at close proximity. An Acousonde acoustic and movement recording tag deployed on a calf off Maui, Hawaii captured sounds produced by a singing male escort. Root-mean-square received levels ranged from 126 to 158 dB re 1 μPa. These levels represent rare direct measurements of sound to which a newly born humpback calf may be naturally exposed by a conspecific, and may provide a basis for informed decisions regarding anthropogenic sound levels projected near calves.
Reflective echo tomographic imaging using acoustic beams
Kisner, Roger; Santos-Villalobos, Hector J
2014-11-25
An inspection system includes a plurality of acoustic beamformers, where each of the plurality of acoustic beamformers including a plurality of acoustic transmitter elements. The system also includes at least one controller configured for causing each of the plurality of acoustic beamformers to generate an acoustic beam directed to a point in a volume of interest during a first time. Based on a reflected wave intensity detected at a plurality of acoustic receiver elements, an image of the volume of interest can be generated.
NASA Astrophysics Data System (ADS)
Walterscheid, R. L.; Azeem, S. I.
2017-12-01
Acoustic waves generated in the lower atmosphere may become an important source of variably in the upper atmosphere. Although they are excited with small amplitudes they are minimally subject to viscous dissipation and may reach significant amplitudes at F-region altitudes. A number of studies in the 1970s showed clear signatures in ionosonde data in the infrasonic period range attributable to thunder storm activity. We have examined Total Electron Content data from a dense network of over 4000 ground-based GPS receivers over the continental United States during an outbreak of severe weather, including tornados, over Kansas in May 2015. A sequence of GPS TEC images showed clear Traveling Ionospheric Disturbances (TIDs) in the form of concentric rings moving outward from the center of the storm region. The characteristics of the disturbance (phase speed and frequency) were consistent with acoustic waves in the infrasonic range. We have modeled the disturbance by including a tropospheric heat source representing latent heat release from a large thunderstorm. The disturbance at ionospheric altitudes resembles the observed disturbance in terms of phase speed, frequency and horizontal wavelength. We conclude that the observed TIDs in TEC were caused by an acoustic wave generated by deep convection.
Acoustic Environment of Admiralty Inlet: Broadband Noise Measurements
DOE Office of Scientific and Technical Information (OSTI.GOV)
Xu, Jinshan; Deng, Zhiqun; Martinez, Jayson J.
2011-09-30
Admiralty Inlet has been selected as a potential tidal energy site. It is located near shipping lanes, is a highly variable acoustic environment, and is frequented by the highly endangered southern resident killer whale (SRKW). Resolving environmental impacts is the first step to receiving approval to deploy tidal turbines at Admiralty Inlet. Of particular concern is the potential for blade strike or other negative interactions between the SRKW and the tidal turbine. A variety of technologies including passive and active monitoring systems are being considered as potential tools to determine the presence of SRKW in the vicinity of the turbines.more » Broadband noise level measurements are critical for the determination of design and operation specifications of all marine and hydrokinetic energy capture technologies. Acoustic environment data at the proposed site was acquired at different depths using a cabled vertical line array (VLA) with four calibrated hydrophones. The sound pressure level (SPL) power spectrum density was estimated based on the fast Fourier transform. This study describes the first broadband SPL measurements for this site at different depths with frequency ranging from 10 kHz to 480 kHz in combination with other information. To understand the SPL caused by this bedload transport, three different pressure sensors with temperature and conductivity were also assembled on the VLA to measure the conditions at the hydrophone deployment depth. The broadband SPL levels at frequency ranges of 3 kHz to 7 kHz as a function of depth were estimated. Only the hydrophone at an average depth of 40 m showed the strong dependence of SPL with distance from the bottom, which was possibly caused by the cobbles shifting on the seabed. Automatic Identification System data were also studied to understand the SPL measurements.« less
Passive metamaterial-based acoustic holograms in ultrasound energy transfer systems
NASA Astrophysics Data System (ADS)
Bakhtiari-Nejad, Marjan; Elnahhas, Ahmed; Hajj, Muhammad R.; Shahab, Shima
2018-03-01
Contactless energy transfer (CET) is a technology that is particularly relevant in applications where wired electrical contact is dangerous or impractical. Furthermore, it would enhance the development, use, and reliability of low-power sensors in applications where changing batteries is not practical or may not be a viable option. One CET method that has recently attracted interest is the ultrasonic acoustic energy transfer, which is based on the reception of acoustic waves at ultrasonic frequencies by a piezoelectric receiver. Patterning and focusing the transmitted acoustic energy in space is one of the challenges for enhancing the power transmission and locally charging sensors or devices. We use a mathematically designed passive metamaterial-based acoustic hologram to selectively power an array of piezoelectric receivers using an unfocused transmitter. The acoustic hologram is employed to create a multifocal pressure pattern in the target plane where the receivers are located inside focal regions. We conduct multiphysics simulations in which a single transmitter is used to power multiple receivers with an arbitrary two-dimensional spatial pattern via wave controlling and manipulation, using the hologram. We show that the multi-focal pressure pattern created by the passive acoustic hologram will enhance the power transmission for most receivers.
Warren, Victoria E; Marques, Tiago A; Harris, Danielle; Thomas, Len; Tyack, Peter L; Aguilar de Soto, Natacha; Hickmott, Leigh S; Johnson, Mark P
2017-03-01
Passive acoustic monitoring has become an increasingly prevalent tool for estimating density of marine mammals, such as beaked whales, which vocalize often but are difficult to survey visually. Counts of acoustic cues (e.g., vocalizations), when corrected for detection probability, can be translated into animal density estimates by applying an individual cue production rate multiplier. It is essential to understand variation in these rates to avoid biased estimates. The most direct way to measure cue production rate is with animal-mounted acoustic recorders. This study utilized data from sound recording tags deployed on Blainville's (Mesoplodon densirostris, 19 deployments) and Cuvier's (Ziphius cavirostris, 16 deployments) beaked whales, in two locations per species, to explore spatial and temporal variation in click production rates. No spatial or temporal variation was detected within the average click production rate of Blainville's beaked whales when calculated over dive cycles (including silent periods between dives); however, spatial variation was detected when averaged only over vocal periods. Cuvier's beaked whales exhibited significant spatial and temporal variation in click production rates within vocal periods and when silent periods were included. This evidence of variation emphasizes the need to utilize appropriate cue production rates when estimating density from passive acoustic data.
Segura-Garcia, Jaume; Navarro-Ruiz, Juan Miguel; Perez-Solano, Juan J; Montoya-Belmonte, Jose; Felici-Castell, Santiago; Cobos, Maximo; Torres-Aranda, Ana M
2018-02-26
Sound pleasantness or annoyance perceived in urban soundscapes is a major concern in environmental acoustics. Binaural psychoacoustic parameters are helpful to describe generic acoustic environments, as it is stated within the ISO 12913 framework. In this paper, the application of a Wireless Acoustic Sensor Network (WASN) to evaluate the spatial distribution and the evolution of urban acoustic environments is described. Two experiments are presented using an indoor and an outdoor deployment of a WASN with several nodes using an Internet of Things (IoT) environment to collect audio data and calculate meaningful parameters such as the sound pressure level, binaural loudness and binaural sharpness. A chunk of audio is recorded in each node periodically with a microphone array and the binaural rendering is conducted by exploiting the estimated directional characteristics of the incoming sound by means of DOA estimation. Each node computes the parameters in a different location and sends the values to a cloud-based broker structure that allows spatial statistical analysis through Kriging techniques. A cross-validation analysis is also performed to confirm the usefulness of the proposed system.
Montoya-Belmonte, Jose; Cobos, Maximo; Torres-Aranda, Ana M.
2018-01-01
Sound pleasantness or annoyance perceived in urban soundscapes is a major concern in environmental acoustics. Binaural psychoacoustic parameters are helpful to describe generic acoustic environments, as it is stated within the ISO 12913 framework. In this paper, the application of a Wireless Acoustic Sensor Network (WASN) to evaluate the spatial distribution and the evolution of urban acoustic environments is described. Two experiments are presented using an indoor and an outdoor deployment of a WASN with several nodes using an Internet of Things (IoT) environment to collect audio data and calculate meaningful parameters such as the sound pressure level, binaural loudness and binaural sharpness. A chunk of audio is recorded in each node periodically with a microphone array and the binaural rendering is conducted by exploiting the estimated directional characteristics of the incoming sound by means of DOA estimation. Each node computes the parameters in a different location and sends the values to a cloud-based broker structure that allows spatial statistical analysis through Kriging techniques. A cross-validation analysis is also performed to confirm the usefulness of the proposed system. PMID:29495407
NASA Astrophysics Data System (ADS)
Hamilton, Mark F.
1990-12-01
This report discusses five projects all of which involve basic theoretical research in nonlinear acoustics: (1) pulsed finite amplitude sound beams are studied with a recently developed time domain computer algorithm that solves the KZK nonlinear parabolic wave equation; (2) nonlinear acoustic wave propagation in a liquid layer is a study of harmonic generation and acoustic soliton information in a liquid between a rigid and a free surface; (3) nonlinear effects in asymmetric cylindrical sound beams is a study of source asymmetries and scattering of sound by sound at high intensity; (4) effects of absorption on the interaction of sound beams is a completed study of the role of absorption in second harmonic generation and scattering of sound by sound; and (5) parametric receiving arrays is a completed study of parametric reception in a reverberant environment.
Joint Eglin Acoustics Week 2013 Data Report
NASA Technical Reports Server (NTRS)
Conner, David A.; Stephenson, James H.; Sim, Ben W.; Watts, Michael E.; Greenwood, Eric; Smith, Charles D.
2017-01-01
Far-field acoustic measurements were obtained for the AH-64D, HH-60M and CV-22B at the Eglin AFB, Test Area C-72, in July/August 2013. The primary purpose for this flight test was to obtain a benchmark database of detailed acoustic source noise characteristics for the aircraft operating at typical mission gross weights over a range of typical mission operating conditions. Data were acquired for a range of steady-state level and descending flight conditions, hover, and a variety of unsteady maneuver conditions. Between 30 and 37 microphones were deployed during these tests. Vehicle position and state data, as well as weather data were acquired simultaneously with the acoustic data. This paper describes the test aircraft, onboard instrumentation, ground instrumentation, and the data acquired. Data from this test are available upon request and review.
Effects of acoustic deterrents on foraging bats
Johnson, Joshua B.; Ford, W. Mark; Rodrigue, Jane L.; Edwards, John W.
2012-01-01
Significant bat mortality events associated with wind energy expansion, particularly in the Appalachians, have highlighted the need for development of possible mitigation practices to reduce or prevent strike mortality. Other than increasing turbine cut-in speed, acoustic deterrents probably hold the greatest promise for reducing bat mortality. However, acoustic deterrent effectiveness and practicality has not been experimentally examined and is limited to site-specific case studies. Accordingly, we used a crossover experimental design with prior control period to show that bat activity was reduced 17.1 percent by the deployment of ultrasonic deterrents placed around gauged watershed weir ponds on the Fernow Experimental Forest in West Virginia. We caution that while our results should not be extrapolated to the scope of a typical wind energy production facility, the results warrant further research on the use of acoustic deterrents to reduce bat fatalities.
Manipulating Liquids With Acoustic Radiation Pressure Phased Arrays
NASA Technical Reports Server (NTRS)
Oeftering, Richard C.
1999-01-01
High-intensity ultrasound waves can produce the effects of "Acoustic Radiation Pressure" (ARP) and "acoustic streaming." These effects can be used to propel liquid flows and to apply forces that can be used to move or manipulate floating objects or liquid surfaces. NASA's interest in ARP includes the remote-control agitation of liquids and the manipulation of bubbles and drops in liquid experiments and propellant systems. A high level of flexibility is attained by using a high-power acoustic phased array to generate, steer, and focus a beam of acoustic waves. This is called an Acoustic Radiation Pressure Phased Array, or ARPPA. In this approach, many acoustic transducer elements emit wavelets that converge into a single beam of sound waves. Electronically coordinating the timing, or "phase shift," of the acoustic waves makes it possible to form a beam with a predefined direction and focus. Therefore, a user can direct the ARP force at almost any desired point within a liquid volume. ARPPA lets experimenters manipulate objects anywhere in a test volume. This flexibility allow it to be used for multiple purposes, such as to agitate liquids, deploy and manipulate drops or bubbles, and even suppress sloshing in spacecraft propellant tanks.
3-D acoustic waveform simulation and inversion at Yasur Volcano, Vanuatu
NASA Astrophysics Data System (ADS)
Iezzi, A. M.; Fee, D.; Matoza, R. S.; Austin, A.; Jolly, A. D.; Kim, K.; Christenson, B. W.; Johnson, R.; Kilgour, G.; Garaebiti, E.; Kennedy, B.; Fitzgerald, R.; Key, N.
2016-12-01
Acoustic waveform inversion shows promise for improved eruption characterization that may inform volcano monitoring. Well-constrained inversion can provide robust estimates of volume and mass flux, increasing our ability to monitor volcanic emissions (potentially in real-time). Previous studies have made assumptions about the multipole source mechanism, which can be thought of as the combination of pressure fluctuations from a volume change, directionality, and turbulence. This infrasound source could not be well constrained up to this time due to infrasound sensors only being deployed on Earth's surface, so the assumption of no vertical dipole component has been made. In this study we deploy a high-density seismo-acoustic network, including multiple acoustic sensors along a tethered balloon around Yasur Volcano, Vanuatu. Yasur has frequent strombolian eruptions from any one of its three active vents within a 400 m diameter crater. The third dimension (vertical) of pressure sensor coverage allows us to begin to constrain the acoustic source components in a profound way, primarily the horizontal and vertical components and their previously uncharted contributions to volcano infrasound. The deployment also has a geochemical and visual component, including FLIR, FTIR, two scanning FLYSPECs, and a variety of visual imagery. Our analysis employs Finite-Difference Time-Domain (FDTD) modeling to obtain the full 3D Green's functions for each propagation path. This method, following Kim et al. (2015), takes into account realistic topographic scattering based on a digital elevation model created using structure-from-motion techniques. We then invert for the source location and source-time function, constraining the contribution of the vertical sound radiation to the source. The final outcome of this inversion is an infrasound-derived volume flux as a function of time, which we then compare to those derived independently from geochemical techniques as well as the inversion of
Feasibility of Tracking Fish with Acoustic Transmitters in the Ice Harbor Dam Tailrace
Ingraham, John M.; Deng, Z. Daniel; Martinez, Jayson J.; Trumbo, Bradly A.; Mueller, Robert P.; Weiland, Mark A.
2014-01-01
The Juvenile Salmon Acoustic Telemetry System (JSATS) has been used at many dams but has never been deployed in the near-dam tailrace environment. The use of JSATS in the tailrace is of interest to fishery managers to evaluate downstream passage behavior of juvenile salmonids and dam approach behavior of upstream migrating adult salmon and lamprey. The acoustic noise level and detection range of JSATS were studied to determine the feasibility of deploying JSATS in the Ice Harbor Dam tailrace. The noise level measured from the powerhouse deck was less than 104 dB re 1 μPa except for the turbine outlet near the spillway, and 350 m downstream of the dam, the noise level was less than 106 dB. The measured noise levels would allow a theoretical detection range of 100 m to 350 m and 85 m to 320 m, respectively. Validation experiments showed that the detection range is 113 to 184 m using hydrophones deployed from the powerhouse deck and 148 m using hydrophones deployed 500 m downstream of the dam. PMID:24522516
Applications of surface acoustic and shallow bulk acoustic wave devices
NASA Astrophysics Data System (ADS)
Campbell, Colin K.
1989-10-01
Surface acoustic wave (SAW) device coverage includes delay lines and filters operating at selected frequencies in the range from about 10 MHz to 11 GHz; modeling with single-crystal piezoelectrics and layered structures; resonators and low-loss filters; comb filters and multiplexers; antenna duplexers; harmonic devices; chirp filters for pulse compression; coding with fixed and programmable transversal filters; Barker and quadraphase coding; adaptive filters; acoustic and acoustoelectric convolvers and correlators for radar, spread spectrum, and packet radio; acoustooptic processors for Bragg modulation and spectrum analysis; real-time Fourier-transform and cepstrum processors for radar and sonar; compressive receivers; Nyquist filters for microwave digital radio; clock-recovery filters for fiber communications; fixed-, tunable-, and multimode oscillators and frequency synthesizers; acoustic charge transport; and other SAW devices for signal processing on gallium arsenide. Shallow bulk acoustic wave device applications include gigahertz delay lines, surface-transverse-wave resonators employing energy-trapping gratings, and oscillators with enhanced performance and capability.
Broadband Acoustic Environment at a Tidal Energy Site in Puget Sound
DOE Office of Scientific and Technical Information (OSTI.GOV)
Xu, Jinshan; Deng, Zhiqun; Martinez, Jayson J.
2012-04-04
Admiralty Inlet has been selected as a potential tidal energy site. It is located near shipping lanes, is a highly variable acoustic environment, and is frequented by the endangered southern resident killer whale (SRKW). Resolving environmental impacts is the first step to receiving approval to deploy tidal turbines. Several monitoring technologies are being considered to determine the presence of SRKW near the turbines. Broadband noise level measurements are critical for determining design and operational specifications of these technologies. Acoustic environment data at the proposed site was acquired at different depths using a cabled vertical line array from three different cruisesmore » during high tidal period in February, May, and June 2011. The ambient noise level decreases approximately 25 dB re 1 μPa per octave from frequency ranges of 1 kHz to 70 kHz, and increases approximately 20 dB re 1 μPa per octave for the frequency from 70 kHz to 200 kHz. The difference of noise pressure levels in different months varies from 10 to 30 dB re 1 μPa for the frequency range below 70 kHz. Commercial shipping and ferry vessel traffic were found to be the most significant contributors to sound pressure levels for the frequency range from 100 Hz to 70 kHz, and the variation could be as high as 30 dB re 1 μPa. These noise level measurements provide the basic information for designing and evaluating both active and passive monitoring systems proposed for deploying and operating for tidal power generation alert system.« less
Two-port network analysis and modeling of a balanced armature receiver.
Kim, Noori; Allen, Jont B
2013-07-01
Models for acoustic transducers, such as loudspeakers, mastoid bone-drivers, hearing-aid receivers, etc., are critical elements in many acoustic applications. Acoustic transducers employ two-port models to convert between acoustic and electromagnetic signals. This study analyzes a widely-used commercial hearing-aid receiver ED series, manufactured by Knowles Electronics, Inc. Electromagnetic transducer modeling must consider two key elements: a semi-inductor and a gyrator. The semi-inductor accounts for electromagnetic eddy-currents, the 'skin effect' of a conductor (Vanderkooy, 1989), while the gyrator (McMillan, 1946; Tellegen, 1948) accounts for the anti-reciprocity characteristic [Lenz's law (Hunt, 1954, p. 113)]. Aside from Hunt (1954), no publications we know of have included the gyrator element in their electromagnetic transducer models. The most prevalent method of transducer modeling evokes the mobility method, an ideal transformer instead of a gyrator followed by the dual of the mechanical circuit (Beranek, 1954). The mobility approach greatly complicates the analysis. The present study proposes a novel, simplified and rigorous receiver model. Hunt's two-port parameters, the electrical impedance Ze(s), acoustic impedance Za(s) and electro-acoustic transduction coefficient Ta(s), are calculated using ABCD and impedance matrix methods (Van Valkenburg, 1964). The results from electrical input impedance measurements Zin(s), which vary with given acoustical loads, are used in the calculation (Weece and Allen, 2010). The hearing-aid receiver transducer model is designed based on energy transformation flow [electric→ mechanic→ acoustic]. The model has been verified with electrical input impedance, diaphragm velocity in vacuo, and output pressure measurements. This receiver model is suitable for designing most electromagnetic transducers and it can ultimately improve the design of hearing-aid devices by providing a simplified yet accurate, physically
Interaction of electromagnetic and acoustic waves in a stochastic atmosphere
NASA Technical Reports Server (NTRS)
Bhatnagar, N.; Peterson, A. M.
1979-01-01
In the Stanford radio acoustic sounding system (RASS) an electromagnetic signal is made to scatter from a moving acoustic pulse train. Under a Bragg-scatter condition maximum electromagnetic scattering occurs. The scattered radio signal contains temperature and wind information as a function of the acoustic-pulse position. In this investigation RASS performance is assessed in an atmosphere characterized by the presence of turbulence and mean atmospheric parameters. The only assumption made is that the electromagnetic wave is not affected by stochastic perturbations in the atmosphere. It is concluded that the received radio signal depends strongly on the intensity of turbulence for altitudes of the acoustic pulse greater than the coherence length of propagation. The effect of mean vertical wind and mean temperature on the strength of the received signal is also demonstrated to be insignificant. Mean horizontal winds, however, shift the focus of the reflected electromagnetic energy from its origin, resulting in a decrease in received signal level when a monostatic radio-frequency (RF) system is used. For a bistatic radar configuration with space diversified receiving antennas, the shifting of the acoustic pulse makes possible the remote measurement of the horizontal wind component.
Polymer coating of glass microballoons levitated in a focused acoustic field
NASA Technical Reports Server (NTRS)
Young, A. T.; Lee, M. C.; Feng, I.-A.; Elleman, D. D.; Wang, T. G.
1982-01-01
Inertial confinement fusion (ICF) glass microballoons (GMBs) levitated in a focusing radiator acoustic device can be coated with liquid materials by deploying the liquid into the levitation field with a stepped-horn atomizer. The GMB can be forced to the center of the coating liquid with a strong acoustically generated centering force. Water solutions of organic polymers, UV-curable liquid organic monomers, and paraffin waxes have been used to prepare solid coatings on the surface of GMBs using this technique.
Background Studies for Acoustic Neutrino Detection at the South Pole
NASA Technical Reports Server (NTRS)
Abbasi, R.; Abdou, Y.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.;
2011-01-01
The detection of acoustic signals from ultra-high energy neutrino interactions is a promising method to measure the flux of cosmogenic neutrinos expected on Earth. The energy threshold for this process depends strongly on the absolute noise level in the target material. The South Pole Acoustic Test Setup (SPATS), deployed in the upper part of four boreholes of the IceCube Neutrino Observatory, has monitored the noise in Antarctic ice at the geographic South Pole for more than two years down to 500m depth. The noise is very stable and Gaussian distributed. Lacking an in-situ calibration up to now, laboratory measurements have been used to estimate the absolute noise level in the 10 to 50 kHz frequency range to be smaller than 20mPa. Using a threshold trigger, sensors of the South Pole Acoustic Test Setup registered acoustic events in the IceCube detector volume and its vicinity. Acoustic signals from refreezing IceCube holes and from anthropogenic sources have been used to test the localization of acoustic events. An upper limit on the neutrino flux at energies E > 10(exp 11) GeV is derived from acoustic data taken over eight months.
Background studies for acoustic neutrino detection at the South Pole
NASA Astrophysics Data System (ADS)
Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; Benzvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brown, A. M.; Buitink, S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Daughhetee, J.; Davis, J. C.; de Clercq, C.; Demirörs, L.; Denger, T.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; Deyoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Geisler, M.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Heinen, D.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kuehn, K.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lünemann, J.; Madsen, J.; Majumdar, P.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Ono, M.; Panknin, S.; Paul, L.; Pérez de Los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schmidt, T.; Schönwald, A.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stössl, A.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Stür, M.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsk, P.
2012-01-01
The detection of acoustic signals from ultra-high energy neutrino interactions is a promising method to measure the flux of cosmogenic neutrinos expected on Earth. The energy threshold for this process depends strongly on the absolute noise level in the target material. The South Pole Acoustic Test Setup (SPATS), deployed in the upper part of four boreholes of the IceCube Neutrino Observatory, has monitored the noise in Antarctic ice at the geographic South Pole for more than two years down to 500 m depth. The noise is very stable and Gaussian distributed. Lacking an in situ calibration up to now, laboratory measurements have been used to estimate the absolute noise level in the 10-50 kHz frequency range to be smaller than 20 mPa. Using a threshold trigger, sensors of the South Pole Acoustic Test Setup registered acoustic events in the IceCube detector volume and its vicinity. Acoustic signals from refreezing IceCube holes and from anthropogenic sources have been used to test the localization of acoustic events. An upper limit on the neutrino flux at energies Eν > 1011 GeV is derived from acoustic data taken over eight months.
Mental Well-being Considerations in Preparation for Disaster Health Care: Learning From Deployment.
Mäkinen, Tytti H; Miettinen, Sari M; Kernohan, W George
2015-08-01
The mental well-being of internationally deployed disaster-relief workers has become an issue of concern. The psychological consequences for the relief worker being exposed to trauma and threats have been well documented; however, the role of pre-deployment preparation in supporting mental well-being has not received due attention, despite research indicating the need for it. This case series examines the experiences of deployed volunteers of one emergency-relief organization. The aim of this research was to identify the participants' interpretations of the appropriateness of the pre-deployment preparation they had received in light of supporting their mental well-being during and after deployment. The main research questions were: How appropriate was pre-deployment preparation in supporting mental well-being? What elements were lacking, and what else would be useful? Using a hermeneutic phenomenological approach, thematic, semi-structured interviews were conducted with six deployed volunteers of an international emergency-relief organization. Data were analyzed using content analysis. The participants in this study regarded the pre-deployment preparation they had received, on the whole, as appropriate in supporting their mental well-being. The seven main themes identified as important and supportive of mental well-being were: (1) realistic expectations, (2) team building and support, (3) self-awareness and self-care, (4) post-deployment support, (5) practical skills and creative solutions, (6) shared values and beliefs, and (7) safety and security. Specific areas identified as lacking within these themes included communication, self-care, post-deployment support, and safety and security. Themes identified as important for supporting mental well-being in this research largely were consistent with those in previous research. The generally positive experiences of the support received do not reflect results from existing research, where significant shortcomings in
Worcester, Peter F; Dzieciuch, Matthew A; Mercer, James A; Andrew, Rex K; Dushaw, Brian D; Baggeroer, Arthur B; Heaney, Kevin D; D'Spain, Gerald L; Colosi, John A; Stephen, Ralph A; Kemp, John N; Howe, Bruce M; Van Uffelen, Lora J; Wage, Kathleen E
2013-10-01
A series of experiments conducted in the Philippine Sea during 2009-2011 investigated deep-water acoustic propagation and ambient noise in this oceanographically and geologically complex region: (i) the 2009 North Pacific Acoustic Laboratory (NPAL) Pilot Study/Engineering Test, (ii) the 2010-2011 NPAL Philippine Sea Experiment, and (iii) the Ocean Bottom Seismometer Augmentation of the 2010-2011 NPAL Philippine Sea Experiment. The experimental goals included (a) understanding the impacts of fronts, eddies, and internal tides on acoustic propagation, (b) determining whether acoustic methods, together with other measurements and ocean modeling, can yield estimates of the time-evolving ocean state useful for making improved acoustic predictions, (c) improving our understanding of the physics of scattering by internal waves and spice, (d) characterizing the depth dependence and temporal variability of ambient noise, and (e) understanding the relationship between the acoustic field in the water column and the seismic field in the seafloor. In these experiments, moored and ship-suspended low-frequency acoustic sources transmitted to a newly developed distributed vertical line array receiver capable of spanning the water column in the deep ocean. The acoustic transmissions and ambient noise were also recorded by a towed hydrophone array, by acoustic Seagliders, and by ocean bottom seismometers.
Acoustic transducer in system for gas temperature measurement in gas turbine engine
DOE Office of Scientific and Technical Information (OSTI.GOV)
DeSilva, Upul P.; Claussen, Heiko
An apparatus for controlling operation of a gas turbine engine including at least one acoustic transmitter/receiver device located on a flow path boundary structure. The acoustic transmitter/receiver device includes an elongated sound passage defined by a surface of revolution having opposing first and second ends and a central axis extending between the first and second ends, an acoustic sound source located at the first end, and an acoustic receiver located within the sound passage between the first and second ends. The boundary structure includes an opening extending from outside the boundary structure to the flow path, and the second endmore » of the surface of revolution is affixed to the boundary structure at the opening for passage of acoustic signals between the sound passage and the flow path.« less
Evaluation of acoustic telemetry grids for determining aquatic animal movement and survival
Kraus, Richard T.; Holbrook, Christopher; Vandergoot, Christopher; Stewart, Taylor R.; Faust, Matthew D.; Watkinson, Douglas A.; Charles, Colin; Pegg, Mark; Enders, Eva C.; Krueger, Charles C.
2018-01-01
Acoustic telemetry studies have frequently prioritized linear configurations of hydrophone receivers, such as perpendicular from shorelines or across rivers, to detect the presence of tagged aquatic animals. This approach introduces unknown bias when receivers are stationed for convenience at geographic bottlenecks (e.g., at the mouth of an embayment or between islands) as opposed to deployments following a statistical sampling design.We evaluated two-dimensional acoustic receiver arrays (grids: receivers spread uniformly across space) as an alternative approach to provide estimates of survival, movement, and habitat use. Performance of variably-spaced receiver grids (5–25 km spacing) was evaluated by simulating (1) animal tracks as correlated random walks (speed: 0.1–0.9 m/s; turning angle standard deviation: 5–30 degrees); (2) variable tag transmission intervals along each track (nominal delay: 15–300 seconds); and (3) probability of detection of each transmission based on logistic detection range curves (midpoint: 200–1500 m). From simulations, we quantified i) time between successive detections on any receiver (detection time), ii) time between successive detections on different receivers (transit time), and iii) distance between successive detections on different receivers (transit distance).In the most restrictive detection range scenario (200 m), the 95th percentile of transit time was 3.2 days at 5 km grid spacing, 5.7 days at 7 km, and 15.2 days at 25 km; for the 1500 m detection range scenario, it was 0.1 days at 5 km, 0.5 days at 7 km, and 10.8 days at 25 km. These values represented upper bounds on the expected maximum time that an animal could go undetected. Comparison of the simulations with pilot studies on three fishes (walleye Sander vitreus, common carp Cyprinus carpio, and channel catfish Ictalurus punctatus) from two independent large lake ecosystems (lakes Erie and Winnipeg) revealed shorter detection and transit times than what
The acoustic field of singing humpback whales in the vertical plane
NASA Astrophysics Data System (ADS)
Au, Whitlow W. L.; Pack, Adam A.; Lammers, Marc O.; Herman, Louis; Andrews, Kimberly; Deakos, Mark
2003-04-01
A vertical array of five hydrophones was used to measure the acoustic field of singing humpback whales. Once a singer was located, two swimmers with snorkel gear were deployed to determine the orientation of the whale and to position the boat so that the array could be deployed in front of the whale at a minimum standoff distance of 10 m. The spacing of the hydrophones was 7 m with the deepest hydrophone deployed at depth of 35 m. An 8-channel TASCAM recorder having a bandwidth of 24 kHz was used to record the hydrophone signals. The location of the singer was determined by computing the time of arrival differences between the hydrophone signals. The maximum source level varied between individual units in a song, with values between 180 and 190 dB. The acoustic field determined by considering the relative intensity of higher frequency harmonics in the signals indicate that the sounds are projected in the horizontal direction with the singer's head canted downward 45 to 60°. High-frequency harmonics extended beyond 24 kHz, suggesting that humpback whales may have an upper frequency limit of hearing as high as 24 kHz.
Differential phase acoustic microscope for micro-NDE
NASA Technical Reports Server (NTRS)
Waters, David D.; Pusateri, T. L.; Huang, S. R.
1992-01-01
A differential phase scanning acoustic microscope (DP-SAM) was developed, fabricated, and tested in this project. This includes the acoustic lens and transducers, driving and receiving electronics, scanning stage, scanning software, and display software. This DP-SAM can produce mechanically raster-scanned acoustic microscopic images of differential phase, differential amplitude, or amplitude of the time gated returned echoes of the samples. The differential phase and differential amplitude images provide better image contrast over the conventional amplitude images. A specially designed miniature dual beam lens was used to form two foci to obtain the differential phase and amplitude information of the echoes. High image resolution (1 micron) was achieved by applying high frequency (around 1 GHz) acoustic signals to the samples and placing two foci close to each other (1 micron). Tone burst was used in this system to obtain a good estimation of the phase differences between echoes from the two adjacent foci. The system can also be used to extract the V(z) acoustic signature. Since two acoustic beams and four receiving modes are available, there are 12 possible combinations to produce an image or a V(z) scan. This provides a unique feature of this system that none of the existing acoustic microscopic systems can provide for the micro-nondestructive evaluation applications. The entire system, including the lens, electronics, and scanning control software, has made a competitive industrial product for nondestructive material inspection and evaluation and has attracted interest from existing acoustic microscope manufacturers.
Brocato, Robert W.
2016-10-04
An unpowered signal receiver and a method for signal reception detects and responds to very weak signals using pyroelectric devices as impedance transformers and/or demodulators. In some embodiments, surface acoustic wave devices (SAW) are also used. Illustrative embodiments include satellite and long distance terrestrial communications applications.
Apparatus for production of ultrapure amorphous metals utilizing acoustic cooling
NASA Technical Reports Server (NTRS)
Lee, M. C. (Inventor)
1985-01-01
Amorphous metals are produced by forming a molten unit of metal and deploying the unit into a bidirectional acoustical levitating field or by dropping the unit through a spheroidizing zone, a slow quenching zone, and a fast quenching zone in which the sphere is rapidly cooled by a bidirectional jet stream created in the standing acoustic wave field produced between a half cylindrical acoustic driver and a focal reflector or a curved driver and a reflector. The cooling rate can be further augmented first by a cryogenic liquid collar and secondly by a cryogenic liquid jacket surrounding a drop tower. The molten unit is quenched to an amorphous solid which can survive impact in a unit collector or is retrieved by a vacuum chuck.
Acoustic MIMO communications in a very shallow water channel
NASA Astrophysics Data System (ADS)
Zhou, Yuehai; Cao, Xiuling; Tong, Feng
2015-12-01
Underwater acoustic channels pose significant difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multiple input multiple output (MIMO) technologies in wireless communication scenarios, MIMO systems offer a potential solution by enabling multiple spatially parallel communication channels to improve communication performance as well as capacity. For MIMO acoustic communications, deep sea channels offer substantial spatial diversity among multiple channels that can be exploited to address simultaneous multipath and co-channel interference. At the same time, there are increasing requirements for high speed underwater communication in very shallow water area (for example, a depth less than 10 m). In this paper, a space-time multichannel adaptive receiver consisting of multiple decision feedback equalizers (DFE) is adopted as the receiver for a very shallow water MIMO acoustic communication system. The performance of multichannel DFE receivers with relatively small number of receiving elements are analyzed and compared with that of the multichannel time reversal receiver to evaluate the impact of limited spatial diversity on multi-channel equalization and time reversal processing. The results of sea trials in a very shallow water channel are presented to demonstrate the feasibility of very shallow water MIMO acoustic communication.
Madsen, T; Sadowa Vedtofte, M; Nordentoft, M; Ravnborg Nissen, L; Bo Andersen, S
2017-06-01
Insight on how different missions have impacted rates of mental health service (MHS) utilization is unexplored. We compared postdeployment MHS utilization in a national cohort of first-time deployed to missions in Balkan, Iraq, and Afghanistan respectively. A prospective national cohort study of 13 246 first-time deployed in the period 1996 through 2012 to missions in Balkan area, Iraq, or Afghanistan respectively. Soldiers 'MHS utilization was also compared with a 5:1 sex-, age-, and calendar year-matched never-deployed background population. Postdeployment utilization of MHS was retrieved from national coverage registers. Using Cox survival analyses, participants were followed and compared with regard to receiving three different types of psychiatric services: (i) admission to psychiatric hospital, (ii) psychiatric outpatient contact, and (iii) prescriptions of psychotropics. Utilizing of psychiatric outpatient services and psychotropics was significantly higher in first-time deployed to Iraq and Afghanistan compared with deployed to Balkan. However, the rate of postdeployment admission to psychiatric hospital did not differ between missions. Postdeployment rates of psychiatric admission and psychiatric outpatient treatment were significantly higher in Afghanistan-deployed personnel compared with the background population. Utilization of MHS differed significantly between mission areas and was highest after the latest mission to Afghanistan. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Acoustic transducer for nuclear reactor monitoring
Ahlgren, Frederic F.; Scott, Paul F.
1977-01-01
A transducer to monitor a parameter and produce an acoustic signal from which the monitored parameter can be recovered. The transducer comprises a modified Galton whistle which emits a narrow band acoustic signal having a frequency dependent upon the parameter being monitored, such as the temperature of the cooling media of a nuclear reactor. Multiple locations within a reactor are monitored simultaneously by a remote acoustic receiver by providing a plurality of transducers each designed so that the acoustic signal it emits has a frequency distinct from the frequencies of signals emitted by the other transducers, whereby each signal can be unambiguously related to a particular transducer.
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.
The Components of Good Acoustics in a High Performance School
ERIC Educational Resources Information Center
Stewart, William
2009-01-01
Acoustics has received greater importance in the learning environment in recent years. In August 2000, The Acoustical Society of America (ASA) published the study "Classroom Acoustics: A Resource for Creating Learning Environments with Desirable Listening Conditions" providing a framework for understanding the qualities, descriptors of the…
Acoustic emission monitoring system
Romrell, Delwin M.
1977-07-05
Methods and apparatus for identifying the source location of acoustic emissions generated within an acoustically conductive medium. A plurality of acoustic receivers are communicably coupled to the surface of the medium at a corresponding number of spaced locations. The differences in the reception time of the respective sensors in response to a given acoustic event are measured among various sensor combinations prescribed by the monitoring mode employed. Acoustic reception response encountered subsequent to the reception by a predetermined number of the prescribed sensor combinations are inhibited from being communicated to the processing circuitry, while the time measurements obtained from the prescribed sensor combinations are translated into a position measurement representative of the location on the surface most proximate the source of the emission. The apparatus is programmable to function in six separate and five distinct operating modes employing either two, three or four sensory locations. In its preferred arrangement the apparatus of this invention will re-initiate a monitoring interval if the predetermined number of sensors do not respond to a particular emission within a given time period.
Holtschlag, David J.; Syed, Atiq U.; Kennedy, Gregory W.
2002-01-01
Lake St. Clair is a 430 square mile lake between the state of Michigan and the province of Ontario, which forms part of the international boundary between the United States and Canada in the Great Lakes Basin. Lake St. Clair receives most of its inflow from Lake Huron through St. Clair River, which has an average flow of 182,000 cubic feet per second. The lake discharges to Detroit River, where it flows 32 miles to Lake Erie. Twelve drifting buoys were deployed on Lake St. Clair for 74 hours between August 12-15, 2002 to help investigate flow circulation patterns as part of a source water assessment study of the susceptibility of public water intakes. The buoys contained global positioning system (GPS) receivers to track their movements. Buoys were released in a transect between tethered buoys marking an 800-foot wide navigational channel in the north-central part of the lake just downstream of St. Clair River, and about 15.5 miles northeast of Detroit River. In addition, an acoustic Doppler current profiler (ADCP) was used to measure velocity profiles in a grid of 41 points that spanned the area through which the buoys drifted. Computer animations, which can be viewed through the Internet, were developed to help visualize the results of the buoy deployments and ADCP measurements.
A small long-life acoustic transmitter for studying the behavior of aquatic animals
Lu, J.; Deng, Z. D.; Li, H.; ...
2016-11-21
The lack of stronger acoustic signal, longer service life and smaller size from off-the-shelf transmitters has precluded intensive research for environmental monitoring of certain species using acoustic telemetry techniques. In this study we developed a small long-life acoustic transmitter with the length of approximately 24.2 mm, the diameter of approximately 5.0 mm, and the dry weight of approximately 0.72 g. The new transmitter can generate an acoustic signal at selectable source level between 159 and 163 dB re 1 µPa at 1 m. The new acoustic transmitter has an operation lifetime up to a year or longer at a pulsemore » rate interval of 15 seconds, and also has a signal detection range up to at least 500 meters that enhances detection probability in a quiet environment. Furthermore, the new technology makes long-term acoustic telemetry studies of small fish possible and is being deployed for long-term tracking of juvenile sturgeon.« less
A small long-life acoustic transmitter for studying the behavior of aquatic animals
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lu, J.; Deng, Z. D.; Li, H.
The lack of stronger acoustic signal, longer service life and smaller size from off-the-shelf transmitters has precluded intensive research for environmental monitoring of certain species using acoustic telemetry techniques. In this study we developed a small long-life acoustic transmitter with the length of approximately 24.2 mm, the diameter of approximately 5.0 mm, and the dry weight of approximately 0.72 g. The new transmitter can generate an acoustic signal at selectable source level between 159 and 163 dB re 1 µPa at 1 m. The new acoustic transmitter has an operation lifetime up to a year or longer at a pulsemore » rate interval of 15 seconds, and also has a signal detection range up to at least 500 meters that enhances detection probability in a quiet environment. Furthermore, the new technology makes long-term acoustic telemetry studies of small fish possible and is being deployed for long-term tracking of juvenile sturgeon.« less
Mesoscale variations in acoustic signals induced by atmospheric gravity waves.
Chunchuzov, Igor; Kulichkov, Sergey; Perepelkin, Vitaly; Ziemann, Astrid; Arnold, Klaus; Kniffka, Anke
2009-02-01
The results of acoustic tomographic monitoring of the coherent structures in the lower atmosphere and the effects of these structures on acoustic signal parameters are analyzed in the present study. From the measurements of acoustic travel time fluctuations (periods 1 min-1 h) with distant receivers, the temporal fluctuations of the effective sound speed and wind speed are retrieved along different ray paths connecting an acoustic pulse source and several receivers. By using a coherence analysis of the fluctuations near spatially distanced ray turning points, the internal wave-associated fluctuations are filtered and their spatial characteristics (coherences, horizontal phase velocities, and spatial scales) are estimated. The capability of acoustic tomography in estimating wind shear near ground is shown. A possible mechanism describing the temporal modulation of the near-ground wind field by ducted internal waves in the troposphere is proposed.
Surface acoustic wave dust deposition monitor
Fasching, G.E.; Smith, N.S. Jr.
1988-02-12
A system is disclosed for using the attenuation of surface acoustic waves to monitor real time dust deposition rates on surfaces. The system includes a signal generator, a tone-burst generator/amplifier connected to a transmitting transducer for converting electrical signals into acoustic waves. These waves are transmitted through a path defining means adjacent to a layer of dust and then, in turn, transmitted to a receiving transducer for changing the attenuated acoustic wave to electrical signals. The signals representing the attenuated acoustic waves may be amplified and used in a means for analyzing the output signals to produce an output indicative of the dust deposition rates and/or values of dust in the layer. 8 figs.
Thomas, Len; Jaramillo-Legorreta, Armando; Cardenas-Hinojosa, Gustavo; Nieto-Garcia, Edwyna; Rojas-Bracho, Lorenzo; Ver Hoef, Jay M; Moore, Jeffrey; Taylor, Barbara; Barlow, Jay; Tregenza, Nicholas
2017-11-01
The vaquita is a critically endangered species of porpoise. It produces echolocation clicks, making it a good candidate for passive acoustic monitoring. A systematic grid of sensors has been deployed for 3 months annually since 2011; results from 2016 are reported here. Statistical models (to compensate for non-uniform data loss) show an overall decline in the acoustic detection rate between 2015 and 2016 of 49% (95% credible interval 82% decline to 8% increase), and total decline between 2011 and 2016 of over 90%. Assuming the acoustic detection rate is proportional to population size, approximately 30 vaquita (95% credible interval 8-96) remained in November 2016.
Recent Langley helicopter acoustics contributions
NASA Technical Reports Server (NTRS)
Morgan, Homer G.; Pao, S. P.; Powell, C. A.
1988-01-01
The helicopter acoustics program at NASA Langley has included technology for elements of noise control ranging from sources of noise to receivers of noise. The scope of Langley contributions for about the last decade is discussed. Specifically, the resolution of two certification noise quantification issues by subjective acoustics research, the development status of the helicopter system noise prediction program ROTONET are reviewed and the highlights from research on blade rotational, broadband, and blade vortex interaction noise sources are presented. Finally, research contributions on helicopter cabin (or interior) noise control are presented. A bibliography of publications from the Langley helicopter acoustics program for the past 10 years is included.
Event identification by acoustic signature recognition
DOE Office of Scientific and Technical Information (OSTI.GOV)
Dress, W.B.; Kercel, S.W.
1995-07-01
Many events of interest to the security commnnity produce acoustic emissions that are, in principle, identifiable as to cause. Some obvious examples are gunshots, breaking glass, takeoffs and landings of small aircraft, vehicular engine noises, footsteps (high frequencies when on gravel, very low frequencies. when on soil), and voices (whispers to shouts). We are investigating wavelet-based methods to extract unique features of such events for classification and identification. We also discuss methods of classification and pattern recognition specifically tailored for acoustic signatures obtained by wavelet analysis. The paper is divided into three parts: completed work, work in progress, and futuremore » applications. The completed phase has led to the successful recognition of aircraft types on landing and takeoff. Both small aircraft (twin-engine turboprop) and large (commercial airliners) were included in the study. The project considered the design of a small, field-deployable, inexpensive device. The techniques developed during the aircraft identification phase were then adapted to a multispectral electromagnetic interference monitoring device now deployed in a nuclear power plant. This is a general-purpose wavelet analysis engine, spanning 14 octaves, and can be adapted for other specific tasks. Work in progress is focused on applying the methods previously developed to speaker identification. Some of the problems to be overcome include recognition of sounds as voice patterns and as distinct from possible background noises (e.g., music), as well as identification of the speaker from a short-duration voice sample. A generalization of the completed work and the work in progress is a device capable of classifying any number of acoustic events-particularly quasi-stationary events such as engine noises and voices and singular events such as gunshots and breaking glass. We will show examples of both kinds of events and discuss their recognition likelihood.« less
Instruments and methods acoustic televiewer logging in glacier boreholes
Morin, R.H.; Descamps, G.E.; Cecil, L.D.
2000-01-01
The acoustic televiewer is a geophysical logging instrument that is deployed in a water-filled borehole and operated while trolling. It generates a digital, magnetically oriented image of the borehole wall that is developed from the amplitudes and transit times of acoustic waves emitted from the tool and reflected at the water-wall interface. The transit-time data are also converted to radial distances, from which cross-sectional views of the borehole shape can be constructed. Because the televiewer is equipped with both a three-component magnetometer and a two-component inclinometer, the borehole's trajectory in space is continuously recorded as well. This instrument is routinely used in mining and hydrogeologic applications, but in this investigation it was deployed in two boreholes drilled into Upper Fremont Glacier, Wyoming, U.S.A. The acoustic images recorded in this glacial setting are not as clear as those typically obtained in rocks, due to a lower reflection coefficient for water and ice than for water and rock. Results indicate that the depth and orientation of features intersecting the boreholes can be determined, but that interpreting their physical nature is problematic and requires corroborating information from inspection of cores. Nevertheless, these data can provide some insight into englacial structural characteristics. Additional information derived from the cross-sectional geometry of the borehole, as well as from its trajectory, may also be useful in studies concerned with stress patterns and deformation processes.
Acoustic Manifestations of Natural versus Triggered Lightning
NASA Astrophysics Data System (ADS)
Arechiga, R. O.; Johnson, J. B.; Edens, H. E.; Rison, W.; Thomas, R. J.; Eack, K.; Eastvedt, E. M.; Aulich, G. D.; Trueblood, J.
2010-12-01
Positive leaders are rarely detected by VHF lightning detection systems; positive leader channels are usually outlined only by recoil events. Positive cloud-to-ground (CG) channels are usually not mapped. The goal of this work is to study the types of thunder produced by natural versus triggered lightning and to assess which types of thunder signals have electromagnetic activity detected by the lightning mapping array (LMA). Towards this end we are investigating the lightning detection capabilities of acoustic techniques, and comparing them with the LMA. In a previous study we used array beam forming and time of flight information to locate acoustic sources associated with lightning. Even though there was some mismatch, generally LMA and acoustic techniques saw the same phenomena. To increase the database of acoustic data from lightning, we deployed a network of three infrasound arrays (30 m aperture) during the summer of 2010 (August 3 to present) in the Magdalena mountains of New Mexico, to monitor infrasound (below 20 Hz) and audio range sources due to natural and triggered lightning. The arrays were located at a range of distances (60 to 1400 m) surrounding the triggering site, called the Kiva, used by Langmuir Laboratory to launch rockets. We have continuous acoustic measurements of lightning data from July 20 to September 18 of 2009, and from August 3 to September 1 of 2010. So far, lightning activity around the Kiva was higher during the summer of 2009. We will present acoustic data from several interesting lightning flashes including a comparison between a natural and a triggered one.
Acoustically enhanced heat exchange and drying apparatus
Bramlette, T.T.; Keller, J.O.
1987-07-10
A heat transfer drying apparatus includes an acoustically augmented heat transfer chamber for receiving material to be dried. The chamber includes a first heat transfer gas inlet, a second heat transfer gas inlet, a material inlet, and a gas outlet which also serves as a dried material and gas outlet. A non-pulsing first heat transfer gas source provides a first drying gas to the acoustically augmented heat transfer chamber through the first heat transfer gas inlet. A valveless, continuous second heat transfer gas source provides a second drying gas to the acoustically augmented heat transfer chamber through the second heat transfer gas inlet. The second drying gas also generates acoustic waves which bring about acoustical coupling with the gases in the acoustically augmented heat transfer chamber. The second drying gas itself oscillates at an acoustic frequency of approximately 180 Hz due to fluid mechanical motion in the gas. The oscillations of the second heat transfer gas coupled to the first heat transfer gas in the acoustically augmented heat transfer chamber enhance heat and mass transfer by convection within the chamber. 3 figs.
System definition study of deployable, non-metallic space structures
NASA Technical Reports Server (NTRS)
Stimler, F. J.
1984-01-01
The state of the art for nonmetallic materials and fabrication techniques suitable for future space structures are summarized. Typical subsystems and systems of interest to the space community that are reviewed include: (1) inflatable/rigidized space hangar; (2) flexible/storable acoustic barrier; (3) deployable fabric bulkhead in a space habitat; (4) extendible tunnel for soft docking; (5) deployable space recovery/re-entry systems for personnel or materials; (6) a manned habitat for a space station; (7) storage enclosures external to the space station habitat; (8) attachable work stations; and (9) safe haven structures. Performance parameters examined include micrometeoroid protection; leakage rate prediction and control; rigidization of flexible structures in the space environment; flammability and offgassing; lifetime for nonmetallic materials; crack propagation prevention; and the effects of atomic oxygen and space debris. An expandable airlock for shuttle flight experiments and potential tethered experiments from shuttle are discussed.
High-frequency shear-horizontal surface acoustic wave sensor
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.
High-frequency shear-horizontal surface acoustic wave sensor
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.
A Coaching Intervention to Promote Nutrition and Bone Health in Deployed Soldiers
2015-03-13
to Promote Nutrition and Bone Health in Deployed Soldiers 5b. GRANT NUMBER HU0001-10-1-TS15 5c. PROGRAM ELEMENT NUMBER N/A 6. AUTHOR(S...Purpose: The purpose of this study was to determine if telehealth coaching is superior to one-time nutrition and fitness education regarding...leisure activities. All soldiers received one-time nutrition and fitness education prior to deployment; Telehealth Group received health-related
Geo-Acoustic Doppler Spectroscopy: A Novel Acoustic Technique For Surveying The Seabed
NASA Astrophysics Data System (ADS)
Buckingham, Michael J.
2010-09-01
An acoustic inversion technique, known as Geo-Acoustic Doppler Spectroscopy, has recently been developed for estimating the geo-acoustic parameters of the seabed in shallow water. The technique is unusual in that it utilizes a low-flying, propeller-driven light aircraft as an acoustic source. Both the engine and propeller produce sound and, since they are rotating sources, the acoustic signature of each takes the form of a sequence of narrow-band harmonics. Although the coupling of the harmonics across the air-sea interface is inefficient, due to the large impedance mismatch between air and water, sufficient energy penetrates the sea surface to provide a useable underwater signal at sensors either in the water column or buried in the sediment. The received signals, which are significantly Doppler shifted due to the motion of the aircraft, will have experienced a number of reflections from the seabed and thus they contain information about the sediment. A geo-acoustic inversion of the Doppler-shifted modes associated with each harmonic yields an estimate of the sound speed in the sediment; and, once the sound speed has been determined, the known correlations between it and the remaining geo-acoustic parameters allow all of the latter to be computed. This inversion technique has been applied to aircraft data collected in the shallow water north of Scripps pier, returning values of the sound speed, shear speed, porosity, density and grain size that are consistent with the known properties of the sandy sediment in the channel.
Tracking sperm whales with a towed acoustic vector sensor.
Thode, Aaron; Skinner, Jeff; Scott, Pam; Roswell, Jeremy; Straley, Janice; Folkert, Kendall
2010-11-01
Passive acoustic towed linear arrays are increasingly used to detect marine mammal sounds during mobile anthropogenic activities. However, these arrays cannot resolve between signals arriving from the port or starboard without vessel course changes or multiple cable deployments, and their performance is degraded by vessel self-noise and non-acoustic mechanical vibration. In principle acoustic vector sensors can resolve these directional ambiguities, as well as flag the presence of non-acoustic contamination, provided that the vibration-sensitive sensors can be successfully integrated into compact tow modules. Here a vector sensor module attached to the end of a 800 m towed array is used to detect and localize 1813 sperm whale "clicks" off the coast of Sitka, AK. Three methods were used to identify frequency regimes relatively free of non-acoustic noise contamination, and then the active intensity (propagating energy) of the signal was computed between 4-10 kHz along three orthogonal directions, providing unambiguous bearing estimates of two sperm whales over time. These bearing estimates are consistent with those obtained via conventional methods, but the standard deviations of the vector sensor bearing estimates are twice those of the conventionally-derived bearings. The resolved ambiguities of the bearings deduced from vessel course changes match the vector sensor predictions.
Interaction of electromagnetic and acoustic waves in a stochastic atmosphere
NASA Technical Reports Server (NTRS)
Bhatnagar, N.; Frankel, M. S.; Peterson, A. M.
1977-01-01
This paper considers the interaction of electromagnetic and acoustic waves where a Radio Acoustic Sounding System (RASS) is operated in a stochastic environment characterized by turbulence, winds and mean-temperature gradients. It has been shown that for a RASS operating at acoustic frequencies below a few kilohertz propagating under typical atmospheric conditions, turbulence has little effect on the strength of the received radio signal scattered from the pulse at heights up to a few kilometers. This result implies that the received RF signal level (power) is primarily a function of sound intensity which decreases as x exp minus 2 where x is the altitude.
Acoustical standards in engineering acoustics
NASA Astrophysics Data System (ADS)
Burkhard, Mahlon D.
2004-05-01
The Engineering Acoustics Technical Committee is concerned with the evolution and improvement of acoustical techniques and apparatus, and with the promotion of new applications of acoustics. As cited in the Membership Directory and Handbook (2002), the interest areas include transducers and arrays; underwater acoustic systems; acoustical instrumentation and monitoring; applied sonics, promotion of useful effects, information gathering and transmission; audio engineering; acoustic holography and acoustic imaging; acoustic signal processing (equipment and techniques); and ultrasound and infrasound. Evident connections between engineering and standards are needs for calibration, consistent terminology, uniform presentation of data, reference levels, or design targets for product development. Thus for the acoustical engineer standards are both a tool for practices, for communication, and for comparison of his efforts with those of others. Development of many standards depends on knowledge of the way products are put together for the market place and acoustical engineers provide important input to the development of standards. Acoustical engineers and members of the Engineering Acoustics arm of the Society both benefit from and contribute to the Acoustical Standards of the Acoustical Society.
Acoustic Transmitters for Underwater Neutrino Telescopes
Ardid, Miguel; Martínez-Mora, Juan A.; Bou-Cabo, Manuel; Larosa, Giuseppina; Adrián-Martínez, Silvia; Llorens, Carlos D.
2012-01-01
In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars), high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing received signals. Secondly, a compact acoustic transmitter array has been developed for the calibration of acoustic neutrino detection systems. The array is able to mimic the signature of ultra-high-energy neutrino interaction in emission directivity and signal shape. The technique of parametric acoustic sources has been used to achieve the proposed aim. The developed compact array has practical features such as easy manageability and operation. The prototype designs and the results of different tests are described. The techniques applied for these two acoustic systems are so powerful and versatile that may be of interest in other marine applications using acoustic transmitters. PMID:22666022
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
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.
Impacts of underwater turbulence on acoustical and optical signals and their linkage.
Hou, Weilin; Jarosz, Ewa; Woods, Sarah; Goode, Wesley; Weidemann, Alan
2013-02-25
Acoustical and optical signal transmission underwater is of vital interest for both civilian and military applications. The range and signal to noise during the transmission, as a function of system and water optical properties, in terms of absorption and scattering, determines the effectiveness of deployed electro-optical (EO) technology. The impacts from turbulence have been demonstrated to affect system performance comparable to those from particles by recent studies. This paper examines the impacts from underwater turbulence on both acoustic scattering and EO imaging degradation, and establishes a framework that can be used to correlate these. It is hypothesized here that underwater turbulence would influence the acoustic scattering cross section and the optical turbulence intensity coefficient in a similar manner. Data from a recent field campaign, Skaneateles Optical Turbulence Exercise (SOTEX, July, 2010) is used to examine the above relationship. Results presented here show strong correlation between the acoustic scattering cross-sections and the intensity coefficient related to the modulation transfer function of an EO imaging system. This significant finding will pave ways to utilize long range acoustical returns to predict EO system performance.
Methods And Systems For Using Reference Images In Acoustic Image Processing
Moore, Thomas L.; Barter, Robert Henry
2005-01-04
A method and system of examining tissue are provided in which a field, including at least a portion of the tissue and one or more registration fiducials, is insonified. Scattered acoustic information, including both transmitted and reflected waves, is received from the field. A representation of the field, including both the tissue and the registration fiducials, is then derived from the received acoustic radiation.
Field performance of an acoustic scour-depth monitoring system
Mason, Jr., Robert R.; Sheppard, D. Max
1994-01-01
The Herbert C. Bonner Bridge over Oregon Inlet serves as the only land link between Bodie and Hatteras Islands, part of the Outer Banks of North Carolina. Periodic soundings over the past 30 years have documented channel migration, local scour, and deposition at several pilings that support the bridge. In September 1992, a data-collection system was installed to permit the off-site monitoring of scour at 16 bridge pilings. The system records channel-bed elevations at 15-minute intervals and transmits the data to a satellite receiver. A cellular phone connection also permits downloading and reviewing of the data as they are being collected. A digitally recording, acoustic fathometer is the main component of the system. In November 1993, current velocity, water-surface elevation, wave characteristics, and water temperature measuring instruments were also deployed at the site. Several performance problems relating to the equipment and to the harsh marine environment have not been resolved, but the system has collected and transmitted reliable scour-depth and water-level data.
Coleman, Laci S.; Ford, W. Mark; Dobony, Christopher A.; Britzke, Eric R.
2014-01-01
Concomitant with the emergence and spread of white-nose syndrome (WNS) and precipitous decline of many bat species in North America, natural resource managers need modified and/or new techniques for bat inventory and monitoring that provide robust occupancy estimates. We used Anabat acoustic detectors to determine the most efficient passive acoustic sampling design for optimizing detection probabilities of multiple bat species in a WNS-impacted environment in New York, USA. Our sampling protocol included: six acoustic stations deployed for the entire duration of monitoring as well as a 4 x 4 grid and five transects of 5-10 acoustic units that were deployed for 6-8 night sample durations surveyed during the summers of 2011-2012. We used Program PRESENCE to determine detection probability and site occupancy estimates. Overall, the grid produced the highest detection probabilities for most species because it contained the most detectors and intercepted the greatest spatial area. However, big brown bats (Eptesicus fuscus) and species not impacted by WNS were detected easily regardless of sampling array. Endangered Indiana (Myotis sodalis) and little brown (Myotis lucifugus) and tri-colored bats (Perimyotis subflavus) showed declines in detection probabilities over our study, potentially indicative of continued WNS-associated declines. Identification of species presence through efficient methodologies is vital for future conservation efforts as bat populations decline further due to WNS and other factors.
Bass, Nathan Charles; Guttridge, Tristan L.; Day, Joanna; Brown, Culum
2017-01-01
Accurately estimating contacts between animals can be critical in ecological studies such as examining social structure, predator–prey interactions or transmission of information and disease. While biotelemetry has been used successfully for such studies in terrestrial systems, it is still under development in the aquatic environment. Acoustic telemetry represents an attractive tool to investigate spatio-temporal behaviour of marine fish and has recently been suggested for monitoring underwater animal interactions. To evaluate the effectiveness of acoustic telemetry in recording interindividual contacts, we compared co-occurrence matrices deduced from three types of acoustic receivers varying in detection range in a benthic shark species. Our results demonstrate that (i) associations produced by acoustic receivers with a large detection range (i.e. Vemco VR2W) were significantly different from those produced by receivers with smaller ranges (i.e. Sonotronics miniSUR receivers and proximity loggers) and (ii) the position of individuals within their network, or centrality, also differed. These findings suggest that acoustic receivers with a large detection range may not be the best option to represent true social networks in the case of a benthic marine animal. While acoustic receivers are increasingly used by marine ecologists, we recommend users first evaluate the influence of detection range to depict accurate individual interactions before using these receivers for social or predator–prey studies. We also advocate for combining multiple receiver types depending on the ecological question being asked and the development of multi-sensor tags or testing of new automated proximity loggers, such as the Encounternet system, to improve the precision and accuracy of social and predator–prey interaction studies. PMID:28989756
Acoustic wave propagation and intensity fluctuations in shallow water 2006 experiment
NASA Astrophysics Data System (ADS)
Luo, Jing
Fluctuations of low frequency sound propagation in the presence of nonlinear internal waves during the Shallow Water 2006 experiment are analyzed. Acoustic waves and environmental data including on-board ship radar images were collected simultaneously before, during, and after a strong internal solitary wave packet passed through a source-receiver acoustic track. Analysis of the acoustic wave signals shows temporal intensity fluctuations. These fluctuations are affected by the passing internal wave and agrees well with the theory of the horizontal refraction of acoustic wave propagation in shallow water. The intensity focusing and defocusing that occurs in a fixed source-receiver configuration while internal wave packet approaches and passes the acoustic track is addressed in this thesis. Acoustic ray-mode theory is used to explain the modal evolution of broadband acoustic waves propagating in a shallow water waveguide in the presence of internal waves. Acoustic modal behavior is obtained from the data through modal decomposition algorithms applied to data collected by a vertical line array of hydrophones. Strong interference patterns are observed in the acoustic data, whose main cause is identified as the horizontal refraction referred to as the horizontal Lloyd mirror effect. To analyze this interference pattern, combined Parabolic Equation model and Vertical-mode horizontal-ray model are utilized. A semi-analytic formula for estimating the horizontal Lloyd mirror effect is developed.
NASA Technical Reports Server (NTRS)
Humphreys, William M., Jr.; Lockard, David P.; Khorrami, Mehdi R.; Culliton, William G.; McSwain, Robert G.; Ravetta, Patricio A.; Johns, Zachary
2016-01-01
A new aeroacoustic measurement capability has been developed consisting of a large channelcount, field-deployable microphone phased array suitable for airframe noise flyover measurements for a range of aircraft types and scales. The array incorporates up to 185 hardened, weather-resistant sensors suitable for outdoor use. A custom 4-mA current loop receiver circuit with temperature compensation was developed to power the sensors over extended cable lengths with minimal degradation of the signal to noise ratio and frequency response. Extensive laboratory calibrations and environmental testing of the sensors were conducted to verify the design's performance specifications. A compact data system combining sensor power, signal conditioning, and digitization was assembled for use with the array. Complementing the data system is a robust analysis system capable of near real-time presentation of beamformed and deconvolved contour plots and integrated spectra obtained from array data acquired during flyover passes. Additional instrumentation systems needed to process the array data were also assembled. These include a commercial weather station and a video monitoring / recording system. A detailed mock-up of the instrumentation suite (phased array, weather station, and data processor) was performed in the NASA Langley Acoustic Development Laboratory to vet the system performance. The first deployment of the system occurred at Finnegan Airfield at Fort A.P. Hill where the array was utilized to measure the vehicle noise from a number of sUAS (small Unmanned Aerial System) aircraft. A unique in-situ calibration method for the array microphones using a hovering aerial sound source was attempted for the first time during the deployment.
MURI: Impact of Oceanographic Variability on Acoustic Communications
2011-09-01
multiplexing ( OFDM ), multiple- input/multiple-output ( MIMO ) transmissions, and multi-user single-input/multiple-output (SIMO) communications. Lastly... MIMO - OFDM communications: Receiver design for Doppler distorted underwater acoustic channels,” Proc. Asilomar Conf. on Signals, Systems, and... MIMO ) will be of particular interest. Validating experimental data will be obtained during the ONR acoustic communications experiment in summer 2008
Heat-driven acoustic cooling engine having no moving parts
Wheatley, John C.; Swift, Gregory W.; Migliori, Albert; Hofler, Thomas J.
1989-01-01
A heat-driven acoustic cooling engine having no moving parts receives heat from a heat source. The acoustic cooling engine comprises an elongated resonant pressure vessel having first and second ends. A compressible fluid having a substantial thermal expansion coefficient and capable of supporting an acoustic standing wave is contained in the resonant pressure vessel. The heat source supplies heat to the first end of the vessel. A first heat exchanger in the vessel is spaced-apart from the first end and receives heat from the first end. A first thermodynamic element is adjacent to the first heat exchanger and converts some of the heat transmitted by the first heat exchanger into acoustic power. A second thermodynamic element has a first end located spaced-apart from the first thermodynamic element and a second end farther away from the first thermodynamic element than is its first end. The first end of the second thermodynamic element heats while its second end cools as a consequence of the acoustic power. A second heat exchanger is adjacent to and between the first and second thermodynamic elements. A heat sink outside of the vessel is thermally coupled to and receives heat from the second heat exchanger. The resonant pressure vessel can include a housing less than one-fourth wavelength in length coupled to a reservoir. The housing can include a reduced diameter portion communicating with the reservoir.
PACT - a bottom pressure based, compact deep-ocean tsunameter with acoustic surface coupling
NASA Astrophysics Data System (ADS)
Macrander, A.; Gouretski, V.; Boebel, O.
2009-04-01
The German-Indonsian Tsunami Early Warning System (GITEWS) processes a multitude of information to comprehensively and accurately evaluate the possible risks inherent to seismic events around Indonesia. Within just a few minutes, measurements of the vibration and horizontal movements off the coastal regions of Indonesia provide a clear picture of the location and intensity of a seaquake. However, not every seaquake causes a tsunami, nor is every tsunami caused by a seaquake. To avoid nerve-wrecking and costly false alarms and to protect against tsunamis caused by landslides, the oceanic sea-level must be measured directly. This goal is pursued in the GITEWS work package "ocean instrumentation", aiming at a a highest reliability and redundancy by developing a set of independent instruments, which measure the sea-level both offshore in the deep ocean and at the coast on the islands off Indonesia. Deep ocean sea-level changes less than a centimetre can be detected by pressure gauges deployed at the sea floor. Based on some of the concepts developed as part of the US DART system, a bottom pressure based, acoustically coupled tsunami detector (PACT) was developed under the auspices of the AWI in collaboration with two German SME and with support of University of Bremen and University of Rhode Island. The PACT system records ocean bottom pressure, performs on-board tsunami detection and acoustically relays the data to the surface buoy. However, employing computational powers and communication technologies of the new millennium, PACT integrates the entire sea-floor package (pressure gauge, data logger and analyzer, acoustic modem, acoustic release and relocation aids) into a single unit, i.e. a standard benthos sphere. PACT thereby reduces costs, minimizes the deployment efforts, while maximizing reliability and maintenance intervals. Several PACT systems are scheduled for their first deployment off Indonesia during 2009. In this presentation, the technical specifications
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kilcher, Levi; Thomson, Jim; Talbert, Joe
This work details a methodology for measuring hub height inflow turbulence using moored acoustic Doppler velocimiters (ADVs). This approach is motivated by the shortcomings of alternatives. For example, remote velocity measurements (i.e., from acoustic Doppler profilers) lack sufficient precision for device simulation, and rigid tower-mounted measurements are very expensive and technically challenging in the tidal environment. Moorings offer a low-cost, site-adaptable and robust deployment platform, and ADVs provide the necessary precision to accurately quantify turbulence.
Acoustic emission linear pulse holography
Collins, H. Dale; Busse, Lawrence J.; Lemon, Douglas K.
1985-01-01
Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.
Dynamic-Receive Focusing with High-Frequency Annular Arrays
NASA Astrophysics Data System (ADS)
Ketterling, J. A.; Mamou, J.; Silverman, R. H.
High-frequency ultrasound is commonly employed for ophthalmic and small-animal imaging because of the fine-resolution images it affords. Annular arrays allow improved depth of field and lateral resolution versus commonly used single-element, focused transducers. The best image quality from an annular array is achieved by using synthetic transmit-to-receive focusing while utilizing data from all transmit-to-receive element combinations. However, annular arrays must be laterally scanned to form an image and this requires one pass for each of the array elements when implementing full synthetic transmit-to-receive focusing. A dynamic-receive focusing approach permits a single pass, although at a sacrifice of depth of field and lateral resolution. A five-element, 20-MHz annular array is examined to determine the acoustic beam properties for synthetic and dynamic-receive focusing. A spatial impulse response model is used to simulate the acoustic beam properties for each focusing case and then data acquired from a human eye-bank eye are processed to demonstrate the effect of each approach on image quality.
A comparison of acoustic and visual metrics of sperm whale longline depredation.
Thode, Aaron M; Wild, Lauren; Mathias, Delphine; Straley, Janice; Lunsford, Christopher
2014-05-01
Annual federal stock assessment surveys for Alaskan sablefish also attempt to measure sperm whale depredation by quantifying visual evidence of depredation, including lip remains and damaged fish. A complementary passive acoustic method for quantifying depredation was investigated during the 2011 and 2012 survey hauls. A combination of machine-aided and human analysis counted the number of distinct “creak” sounds detected on autonomous recorders deployed during the survey, emphasizing sounds that are followed by silence (“creak-pauses”), a possible indication of prey capture. These raw counts were then adjusted for variations in background noise levels between deployments. Both a randomized Pearson correlation analysis and a generalized linear model found that noise-adjusted counts of “creak-pauses” were highly correlated with survey counts of lip remains during both years (2012: r(10) = 0.89, p = 1e-3; 2011: r(39) = 0.72, p = 4e-3) and somewhat correlated with observed sablefish damage in 2011 [r(39) = 0.37, p = 0.03], but uncorrelated with other species depredation. The acoustic depredation count was anywhere from 10% to 80% higher than the visual counts, depending on the survey year and assumptions employed. The results suggest that passive acoustics can provide upper bounds on depredation rates; however, the observed correlation breaks down whenever three or more whales are present.
Near- Source, Seismo-Acoustic Signals Accompanying a NASCAR Race at the Texas Motor Speedway
NASA Astrophysics Data System (ADS)
Stump, B. W.; Hayward, C.; Underwood, R.; Howard, J. E.; MacPhail, M. D.; Golden, P.; Endress, A.
2014-12-01
Near-source, seismo-acoustic observations provide a unique opportunity to characterize urban sources, remotely sense human activities including vehicular traffic and monitor large engineering structures. Energy separately coupled into the solid earth and atmosphere provides constraints on not only the location of these sources but also the physics of the generating process. Conditions and distances at which these observations can be made are dependent upon not only local geological conditions but also atmospheric conditions at the time of the observations. In order to address this range of topics, an empirical, seismo-acoustic study was undertaken in and around the Texas Motor Speedway in the Dallas-Ft. Worth area during the first week of April 2014 at which time a range of activities associated with a series of NASCAR races occurred. Nine, seismic sensors were deployed around the 1.5-mile track for purposes of documenting the direct-coupled seismic energy from the passage of the cars and other vehicles on the track. Six infrasound sensors were deployed on a rooftop in a rectangular array configuration designed to provide high frequency beam forming for acoustic signals. Finally, a five-element infrasound array was deployed outside the track in order to characterize how the signals propagate away from the sources in the near-source region. Signals recovered from within the track were able to track and characterize the motion of a variety of vehicles during the race weekend including individual racecars. Seismic data sampled at 1000 sps documented strong Doppler effects as the cars approached and moved away from individual sensors. There were faint seismic signals that arrived at seismic velocity but local acoustic to seismic coupling as supported by the acoustic observations generated the majority of seismic signals. Actual seismic ground motions were small as demonstrated by the dominance of regional seismic signals from a magnitude 4.0 earthquake that arrived at
Dual instrument passive acoustic monitoring of belugas in Cook Inlet, Alaska.
Castellote, Manuel; Small, Robert J; Lammers, Marc O; Jenniges, Justin J; Mondragon, Jeff; Atkinson, Shannon
2016-05-01
As part of a long-term research program, Cook Inlet beluga (Delphinapterus leucas) presence was acoustically monitored with two types of acoustic sensors utilized in tandem in moorings deployed year-round: an ecological acoustic recorder (EAR) and a cetacean and porpoise detector (C-POD). The EAR was used primarily to record the calls, whistles, and buzzes produced by belugas and killer whales (Orcinus orca). The C-POD was used to log and classify echolocation clicks from belugas, killer whales, and porpoises. This paper describes mooring packages that maximized the chances of successful long-term data collection in the particularly challenging Cook Inlet environment, and presents an analytical comparison of odontocete detections obtained by the collocated EAR and C-POD instruments from two mooring locations in the upper inlet. Results from this study illustrate a significant improvement in detecting beluga and killer whale presence when the different acoustic signals detected by EARs and C-PODs are considered together. Further, results from concurrent porpoise detections indicating prey competition and feeding interference with beluga, and porpoise displacement due to ice formation are described.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Vu, Cung Khac; Skelt, Christopher; Nihei, Kurt
A system and method for investigating rock formations outside a borehole are provided. The method includes generating a first compressional acoustic wave at a first frequency by a first acoustic source; and generating a second compressional acoustic wave at a second frequency by a second acoustic source. The first and the second acoustic sources are arranged within a localized area of the borehole. The first and the second acoustic waves intersect in an intersection volume outside the borehole. The method further includes receiving a third shear acoustic wave at a third frequency, the third shear acoustic wave returning to themore » borehole due to a non-linear mixing process in a non-linear mixing zone within the intersection volume at a receiver arranged in the borehole. The third frequency is equal to a difference between the first frequency and the second frequency.« less
Vu, Cung Khac; Nihei, Kurt; Johnson, Paul A; Guyer, Robert; Ten Cate, James A; Le Bas, Pierre-Yves; Larmat, Carene S
2014-12-30
A system and a method for investigating rock formations includes generating, by a first acoustic source, a first acoustic signal comprising a first plurality of pulses, each pulse including a first modulated signal at a central frequency; and generating, by a second acoustic source, a second acoustic signal comprising a second plurality of pulses. A receiver arranged within the borehole receives a detected signal including a signal being generated by a non-linear mixing process from the first-and-second acoustic signal in a non-linear mixing zone within the intersection volume. The method also includes-processing the received signal to extract the signal generated by the non-linear mixing process over noise or over signals generated by a linear interaction process, or both.
Acoustically enhanced heat exchange and drying apparatus
Bramlette, T. Tazwell; Keller, Jay O.
1989-01-01
A heat transfer apparatus includes a first chamber having a first heat transfer gas inlet, a second heat transfer gas inlet, and an outlet. A first heat transfer gas source provides a first gas flow to the first chamber through the first heat transfer gas inlet. A second gas flow through a second chamber connected to the side of the first chamber, generates acoustic waves which bring about acoustical coupling of the first and second gases in the acoustically augmented first chamber. The first chamber may also include a material inlet for receiving material to be dried, in which case the gas outlet serves as a dried material and gas outlet.
HYDROBS: a long-term autonomous mooring for passive acoustic monitoring
NASA Astrophysics Data System (ADS)
Hello, Y.; Royer, J. Y.; Yegikyan, M.
2017-12-01
Passive acoustics proves an effective way for monitoring the low-level seismic activity of the ocean floor and low-frequency sounds from the ocean (baleen whales, sea-state, icebergs). Networks of synchronized autonomous hydrophones have thus been commonly deployed in the world ocean to monitor large sections of mid-oceanic ridges. HYDROBS is an improved system that meet two requirements: an easy access to the data collected by the instruments together with long-term deployments - up to 4 consecutive years - reducing the need of large vessels capable of yearly mooring operations in open seas. The system has two components: a data logger, up-to-date but similar to previous systems, and three messengers, releasable on demand to collect the data. The mooring line itself is classical, with an expandable weight at the sea-bottom to maintain the mooring, an acoustic release to free the mooring line for recovery, a line adjustable to the seafloor depth, and an immerged buoy, holding the acquisition system, to maintain the sensors at a constant depth and to bring the mooring line to the surface for its recovery. The data logger is based on a low-power microprocessor, an A/D-32bit convertor sampling at 250Hz, a 10-8 real time clock and SD card storage. Lithium batteries provide 3-4 years of autonomy. Acoustic communications with the surface-ship provide control over all functionalities at deployment and a health bulletin on demand. The 3 shuttles, encapsulated in 13" glass spheres, use the same CPU board and clock as the main station. Data transfer from the data logger to the shuttles is wireless (1Mbit/s digital inductive through water). Data are duplicated once per day on shuttles N and N+1 for redundancy. Prior to their release by acoustic command, the shuttles are synchronized with the master clock. At sea-surface, shuttles (as the main unit) look for GPS time and calculate their clock drift. So, the master clock drift can be monitored over time at every shuttle release
Acoustic simulation in architecture with parallel algorithm
NASA Astrophysics Data System (ADS)
Li, Xiaohong; Zhang, Xinrong; Li, Dan
2004-03-01
In allusion to complexity of architecture environment and Real-time simulation of architecture acoustics, a parallel radiosity algorithm was developed. The distribution of sound energy in scene is solved with this method. And then the impulse response between sources and receivers at frequency segment, which are calculated with multi-process, are combined into whole frequency response. The numerical experiment shows that parallel arithmetic can improve the acoustic simulating efficiency of complex scene.
Solid Surface Wetting and the Deployment of Drops in Microgravity
NASA Technical Reports Server (NTRS)
Trinh, E. H.; Depew, J.
1994-01-01
The complete or partial deployment of liquid samples in low gravity is primarily influenced by the interfacial properties of the specific liquid and solid materials used because the overwhelming bias of the Earth gravitational acceleration is removed. This study addresses the engineering aspects of injecting and deploying drops of prescribed volume into an acoustic positioning chamber in microgravity. The specific problems of interest are the design, testing, and implementation of injector tips to be used in a simuttaneously retracting dual-injector system used in the Drop Physics Module microgravity experiment facility. Prior to release, the liquid to be deployed must be retained within a restricted area at the very end of the injectors even under dynamic stimuli due to continuous injection flow as well as to the stepped motion of the injectors, and the final released drop must have a well determined volume as well as negligible residual linear or angular momentum from the deployment process. The outcome of Earthbased short-duration low gravity experiments had been the selection of two types of injector tips which were flown as back-up parts and were successfully utilized during the USML-1 Spacelab mission. The combination of a larger contact surface, liquid pinning with a sharp edge, and selective coating of strategic tip surfaces with a non-wetting compound has allowed a significant increase in the success rate of deployment of simple and compound drops of aqueous solutions of glycerol and silicone oil. The diameter of the samples studied in the Drop Physics Module ranged between 0.3 and 2.7 cm. The tests conducted onsrbit with a manually operated small device have allowed the calibration of the volume deployed for a few drop sizes. The design for improved tips to be used during the next USML flight is based on these results.
Trade-off Analysis of Underwater Acoustic Sensor Networks
NASA Astrophysics Data System (ADS)
Tuna, G.; Das, R.
2017-09-01
In the last couple of decades, Underwater Acoustic Sensor Networks (UASNs) were started to be used for various commercial and non-commercial purposes. However, in underwater environments, there are some specific inherent constraints, such as high bit error rate, variable and large propagation delay, limited bandwidth capacity, and short-range communications, which severely degrade the performance of UASNs and limit the lifetime of underwater sensor nodes as well. Therefore, proving reliability of UASN applications poses a challenge. In this study, we try to balance energy consumption of underwater acoustic sensor networks and minimize end-to-end delay using an efficient node placement strategy. Our simulation results reveal that if the number of hops is reduced, energy consumption can be reduced. However, this increases end-to-end delay. Hence, application-specific requirements must be taken into consideration when determining a strategy for node deployment.
Reactor power system deployment and startup
NASA Technical Reports Server (NTRS)
Wetch, J. R.; Nelin, C. J.; Britt, E. J.; Klein, G.
1985-01-01
This paper addresses issues that should receive further examination in the near-term as concept selection for development of a U.S. space reactor power system is approached. The issues include: the economics, practicality and system reliability associated with transfer of nuclear spacecraft from low earth shuttle orbits to operational orbits, via chemical propulsion versus nuclear electric propulsion; possible astronaut supervised reactor and nuclear electric propulsion startup in low altitude Shuttle orbit; potential deployment methods for nuclear powered spacecraft from Shuttle; the general public safety of low altitude startup and nuclear safe and disposal orbits; the question of preferred reactor power level; and the question of frozen versus molten alkali metal coolant during launch and deployment. These issues must be considered now because they impact the SP-100 concept selection, power level selection, weight and size limits, use of deployable radiators, reliability requirements, and economics, as well as the degree of need for and the urgency of developing space reactor power systems.
Smith, Kevin B; Abrantes, Antonio A M; Larraza, Andres
2003-06-01
The shallow water acoustic communication channel is characterized by strong signal degradation caused by multipath propagation and high spatial and temporal variability of the channel conditions. At the receiver, multipath propagation causes intersymbol interference and is considered the most important of the channel distortions. This paper examines the application of time-reversal acoustic (TRA) arrays, i.e., phase-conjugated arrays (PCAs), that generate a spatio-temporal focus of acoustic energy at the receiver location, eliminating distortions introduced by channel propagation. This technique is self-adaptive and automatically compensates for environmental effects and array imperfections without the need to explicitly characterize the environment. An attempt is made to characterize the influences of a PCA design on its focusing properties with particular attention given to applications in noncoherent underwater acoustic communication systems. Due to the PCA spatial diversity focusing properties, PC arrays may have an important role in an acoustic local area network. Each array is able to simultaneously transmit different messages that will focus only at the destination receiver node.
He, Chengbing; Xi, Rui; Wang, Han; Jing, Lianyou; Shi, Wentao; Zhang, Qunfei
2017-01-01
Phase-coherent underwater acoustic (UWA) communication systems typically employ multiple hydrophones in the receiver to achieve spatial diversity gain. However, small underwater platforms can only carry a single transducer which can not provide spatial diversity gain. In this paper, we propose single-carrier with frequency domain equalization (SC-FDE) for phase-coherent synthetic aperture acoustic communications in which a virtual array is generated by the relative motion between the transmitter and the receiver. This paper presents synthetic aperture acoustic communication results using SC-FDE through data collected during a lake experiment in January 2016. The performance of two receiver algorithms is analyzed and compared, including the frequency domain equalizer (FDE) and the hybrid time frequency domain equalizer (HTFDE). The distances between the transmitter and the receiver in the experiment were about 5 km. The bit error rate (BER) and output signal-to-noise ratio (SNR) performances with different receiver elements and transmission numbers were presented. After combining multiple transmissions, error-free reception using a convolution code with a data rate of 8 kbps was demonstrated. PMID:28684683
Constrained Surface-Level Gateway Placement for Underwater Acoustic Wireless Sensor Networks
NASA Astrophysics Data System (ADS)
Li, Deying; Li, Zheng; Ma, Wenkai; Chen, Hong
One approach to guarantee the performance of underwater acoustic sensor networks is to deploy multiple Surface-level Gateways (SGs) at the surface. This paper addresses the connected (or survivable) Constrained Surface-level Gateway Placement (C-SGP) problem for 3-D underwater acoustic sensor networks. Given a set of candidate locations where SGs can be placed, our objective is to place minimum number of SGs at a subset of candidate locations such that it is connected (or 2-connected) from any USN to the base station. We propose a polynomial time approximation algorithm for the connected C-SGP problem and survivable C-SGP problem, respectively. Simulations are conducted to verify our algorithms' efficiency.
Acoustic cavitation of individual ultrasound contrast agent microbubbles confined in capillaries
NASA Astrophysics Data System (ADS)
Almaqwashi, Ali; McIntyre, David; Ammi, Azzdine
2011-10-01
Ultrasound targeted therapies mainly rely on the inertial cavitation of ultrasound contrast agent (UCA) microbubbles. Our objective is to determine the cavitation acoustic pressure threshold for the destruction of UCA microbubbles inside cellulose capillaries. Acoustic emission from individual Optison microbubbles confined inside a 200-μm diameter capillary was detected using a passive cavitation detection system. Excitation signals from a 2.25 MHz transmitter were applied to the microbubbles while their acoustic emission was detected by a broadband 15 MHz receiver. Time traces were recorded (100 MHz sampling, 12- bit), and frequency-domain analysis of the received signals was performed to characterize microbubble cavitation. The cavitation acoustic pressure threshold was found to be 1 MPa inside the capillary in comparison with ˜0.7 MPa previously reported for unconfined UCA microbubbles. This work provides a clearer understanding of the role of ultrasound contrast agent dynamics inside a capillary.
Ocean acoustic interferometry.
Brooks, Laura A; Gerstoft, Peter
2007-06-01
Ocean acoustic interferometry refers to an approach whereby signals recorded from a line of sources are used to infer the Green's function between two receivers. An approximation of the time domain Green's function is obtained by summing, over all source positions (stacking), the cross-correlations between the receivers. Within this paper a stationary phase argument is used to describe the relationship between the stacked cross-correlations from a line of vertical sources, located in the same vertical plane as two receivers, and the Green's function between the receivers. Theory and simulations demonstrate the approach and are in agreement with those of a modal based approach presented by others. Results indicate that the stacked cross-correlations can be directly related to the shaded Green's function, so long as the modal continuum of any sediment layers is negligible.
NASA Astrophysics Data System (ADS)
Hamilton, Mark F.
1989-08-01
Four projects are discussed in this annual summary report, all of which involve basic research in nonlinear acoustics: Scattering of Sound by Sound, a theoretical study of two nonconlinear Gaussian beams which interact to produce sum and difference frequency sound; Parametric Receiving Arrays, a theoretical study of parametric reception in a reverberant environment; Nonlinear Effects in Asymmetric Sound Beams, a numerical study of two dimensional finite amplitude sound fields; and Pulsed Finite Amplitude Sound Beams, a numerical time domain solution of the KZK equation.
PREDICTIVE MODELING OF ACOUSTIC SIGNALS FROM THERMOACOUSTIC POWER SENSORS (TAPS)
DOE Office of Scientific and Technical Information (OSTI.GOV)
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-powermore » 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« less
NASA Astrophysics Data System (ADS)
Eickmeier, Justin
Acoustical oceanography is one way to study the ocean, its internal layers, boundaries and all processes occurring within using underwater acoustics. Acoustical sensing techniques allows for the measurement of ocean processes from within that logistically or financially preclude traditional in-situ measurements. Acoustic signals propagate as pressure wavefronts from a source to a receiver through an ocean medium with variable physical parameters. The water column physical parameters that change acoustic wave propagation in the ocean include temperature, salinity, current, surface roughness, seafloor bathymetry, and vertical stratification over variable time scales. The impacts of short-time scale water column variability on acoustic wave propagation include coherent and incoherent surface reflections, wavefront arrival time delay, focusing or defocusing of the intensity of acoustic beams and refraction of acoustic rays. This study focuses on high-frequency broadband acoustic waves, and examines the influence of short-time scale water column variability on broadband high-frequency acoustics, wavefronts, from 7 to 28 kHz, in shallow water. Short-time scale variability is on the order of seconds to hours and the short-spatial scale variability is on the order of few centimeters. Experimental results were collected during an acoustic experiment along 100 m isobaths and data analysis was conducted using available acoustic wave propagation models. Three main topics are studied to show that acoustic waves are viable as a remote sensing tool to measure oceanographic parameters in shallow water. First, coherent surface reflections forming striation patterns, from multipath receptions, through rough surface interaction of broadband acoustic signals with the dynamic sea surface are analyzed. Matched filtered results of received acoustic waves are compared with a ray tracing numerical model using a sea surface boundary generated from measured water wave spectra at the time of
Acoustic Propagation Studies For Sperm Whale Phonation Analysis During LADC Experiments
NASA Astrophysics Data System (ADS)
Sidorovskaia, Natalia A.; Ioup, George E.; Ioup, Juliette W.; Caruthers, Jerald W.
2004-11-01
The Littoral Acoustic Demonstration Center (LADC) conducted a series of passive acoustic experiments in the Northern Gulf of Mexico and the Ligurian Sea in 2001 and 2002. Environmental and acoustic moorings were deployed in areas of large concentrations of marine mammals (mainly, sperm whales). Recordings and analysis of whale phonations are among the objectives of the project. Each mooring had a single autonomously recording hydrophone (Environmental Acoustic Recording System (EARS)) obtained from the U.S. Naval Oceanographic Office after modification to record signals up to 5,859 Hz in the Gulf of Mexico and up to 12,500 Hz in the Ligurian Sea. Self-recording environmental sensors, attached to the moorings, and concurrent environmental ship surveys provided the environmental data for the experiments. The results of acoustic simulations of long-range propagation of the broad-band (500-6,000 Hz) phonation pulses from a hypothetical whale location to the recording hydrophone in the experimental environments are presented. The utilization of the simulation results for an interpretation of the spectral features observed in whale clicks and for the development of tracking algorithms from single hydrophone recordings based on the identification of direct and surface and bottom reflected arrivals are discussed. [Research supported by ONR.
NASA Astrophysics Data System (ADS)
Beranek, Leo L.
2004-05-01
My entry into acoustics began as research assistant to Professor F. V. Hunt at Harvard University. I received my doctorate in 1940 and directed the Electro-Acoustic Laboratory at Harvard from October 1940 until September 1945. In 1947, I became a tenured associate professor at MIT, and, with Richard H. Bolt, formed the consulting firm Bolt and Beranek, that later included Robert B. Newman, becoming BBN. My most significant contributions before 1970 were design of wedge-lined anechoic chambers, systemization of noise reduction in ventilation systems, design of the world's largest muffler for the testing of supersonic jet engines at NASA's Lewis Laboratory in Cleveland, speech interference level, NC noise criterion curves, heading New York Port Authority's noise study that resulted in mufflers on jet aircraft, and steep aircraft climb procedures, and publishing books titled, Acoustical Measurements, Acoustics, Noise Reduction, Noise and Vibration Control, and Music, Acoustics and Architecture. As President of BBN, I supervised the formation of the group that built and operated the ARPANET (1969), which, when split in two (using TCP/IP protocol) became the INTERNET (1984). Since then, I have written two books on Concert Halls and Opera Houses and have consulted on four concert halls and an opera house.
On-orbit deployment anamolies: What can be done?
NASA Technical Reports Server (NTRS)
Freeman, Michael
1992-01-01
Modern communications satellites rely heavily upon deployable appendage (i.e., solar arrays, communications antennas, etc.) to perform vital functions that enable the spacecraft to effectively conduct mission objectives. Communications and telemetry antennas provide the radio-frequency link between the spacecraft and the earth ground station, permitting data to be transmitted and received from the satellite. Solar arrays serve as the principle source of electrical energy to the satellite, and re-charge internal batteries during operation. However, since satellites cannot carry back-up systems, if a solar array fails to deploy, the mission is lost. The subject of on-orbit anomalies related to the deployment of spacecraft appendage, and possible causes of such failures are examined. Topics discussed include mechanical launch loading, on-orbit thermal and solar concerns, reliability of spacecraft pyrotechnics, and practical limitations of ground-based deployment testing. Of particular significance, the article features an in-depth look at the lessons learned from the successful recovery of the Telesat Canada Anik-E2 satellite in 1991.
NASA Technical Reports Server (NTRS)
Sheplak, Mark (Inventor); Nishida, Toshikaza (Inventor); Humphreys, William M. (Inventor); Arnold, David P. (Inventor)
2006-01-01
Embodiments of the present invention described and shown in the specification aid drawings include a combination responsive to an acoustic wave that can be utilized as a dynamic pressure sensor. In one embodiment of the present invention, the combination has a substrate having a first surface and an opposite second surface, a microphone positioned on the first surface of the substrate and having an input and a first output and a second output, wherein the input receives a biased voltage, and the microphone generates an output signal responsive to the acoustic wave between the first output and the second output. The combination further has an amplifier positioned on the first surface of the substrate and having a first input and a second input and an output, wherein the first input of the amplifier is electrically coupled to the first output of the microphone and the second input of the amplifier is electrically coupled to the second output of the microphone for receiving the output sinual from the microphone. The amplifier is spaced from the microphone with a separation smaller than 0.5 mm.
Sequential Bayesian geoacoustic inversion for mobile and compact source-receiver configuration.
Carrière, Olivier; Hermand, Jean-Pierre
2012-04-01
Geoacoustic characterization of wide areas through inversion requires easily deployable configurations including free-drifting platforms, underwater gliders and autonomous vehicles, typically performing repeated transmissions during their course. In this paper, the inverse problem is formulated as sequential Bayesian filtering to take advantage of repeated transmission measurements. Nonlinear Kalman filters implement a random-walk model for geometry and environment and an acoustic propagation code in the measurement model. Data from MREA/BP07 sea trials are tested consisting of multitone and frequency-modulated signals (bands: 0.25-0.8 and 0.8-1.6 kHz) received on a shallow vertical array of four hydrophones 5-m spaced drifting over 0.7-1.6 km range. Space- and time-coherent processing are applied to the respective signal types. Kalman filter outputs are compared to a sequence of global optimizations performed independently on each received signal. For both signal types, the sequential approach is more accurate but also more efficient. Due to frequency diversity, the processing of modulated signals produces a more stable tracking. Although an extended Kalman filter provides comparable estimates of the tracked parameters, the ensemble Kalman filter is necessary to properly assess uncertainty. In spite of mild range dependence and simplified bottom model, all tracked geoacoustic parameters are consistent with high-resolution seismic profiling, core logging P-wave velocity, and previous inversion results with fixed geometries.
Nondestructive online testing method for friction stir welding using acoustic emission
NASA Astrophysics Data System (ADS)
Levikhina, Anastasiya
2017-12-01
The paper reviews the possibility of applying the method of acoustic emission for online monitoring of the friction stir welding process. It is shown that acoustic emission allows the detection of weld defects and their location in real time. The energy of an acoustic signal and the median frequency are suggested to be used as informative parameters. The method of calculating the median frequency with the use of a short time Fourier transform is applied for the identification of correlations between the defective weld structure and properties of the acoustic emission signals received during welding.
A Decade of Ocean Acoustic Measurements from R/P FLIP
NASA Astrophysics Data System (ADS)
D'Spain, G. L.
2002-12-01
Studies of the properties of low frequency acoustic fields in the ocean continue to benefit from the use of manned, stable offshore platforms such as R/P FLIP. A major benefit is providing the at-sea stability required for deployment of extremely large aperture line arrays, line arrays composed of both acoustic motion and acoustic pressure sensors, and arrays that provide measurements in all 3 spatial dimensions. In addition, FLIP provides a high-profile (25 m) observation post with 360 deg coverage for simultaneous visual observations of marine mammals. A few examples of the scientific results that have been achieved over this past decade with ocean acoustic data collected on FLIP are presented. These results include the normal mode decomposition of earthquake T phases to study their generation and water/land coupling characteristics using a 3000 m vertical aperture hydrophone array, simultaneous vertical and horizontal directional information on the underwater sound field from line arrays of hydrophones and geophones, the strange nightime chorusing behavior of fish measured by 3D array aperture, the mirage effect caused by bathymetry changes in inversions for source location in shallow water, and the diving behavior of blue whales determined from 1D recordings of their vocalizations. Presently, FLIP serves as the central data recording platform in ocean acoustic studies using AUV's.
Acoustic Emission Monitoring for Assessment of Steel Bridge Details
NASA Astrophysics Data System (ADS)
Kosnik, D. E.; Hopwood, T.; Corr, D. J.
2011-06-01
Acoustic emission (AE) testing was deployed on details of two large steel Interstate Highway bridges: one cantilever through-truss and one trapezoidal box girder bridge. Quantitative measurements of activity levels at known and suspected crack locations were made by monitoring AE under normal service loads (e.g., live traffic and wind). AE indications were used to direct application of radiography, resulting in identification of a previously unknown flaw, and to inform selection of a retrofit detail.
A compact time reversal emitter-receiver based on a leaky random cavity
Luong, Trung-Dung; Hies, Thomas; Ohl, Claus-Dieter
2016-01-01
Time reversal acoustics (TRA) has gained widespread applications for communication and measurements. In general, a scattering medium in combination with multiple transducers is needed to achieve a sufficiently large acoustical aperture. In this paper, we report an implementation for a cost-effective and compact time reversal emitter-receiver driven by a single piezoelectric element. It is based on a leaky cavity with random 3-dimensional printed surfaces. The random surfaces greatly increase the spatio-temporal focusing quality as compared to flat surfaces and allow the focus of an acoustic beam to be steered over an angle of 41°. We also demonstrate its potential use as a scanner by embedding a receiver to detect an object from its backscatter without moving the TRA emitter. PMID:27811957
NASA Astrophysics Data System (ADS)
Gurrola, H.; Pratt, K. W.; Pulliam, J.; Dunbar, J. A.
2011-12-01
In summer of 2010, 21 broadband seismographs were installed at 16-18 km spacing along a transect running from Johnson City, TX, (on the Edwards Plateau), to Matagorda Island to study the current structure of this rifted passive margin. The large magnetic anomaly that parallels the coast throughout the Gulf region moves on-shore beneath our transect such that we will be able to investigate the source of this anomaly. A second important target that will be imaged in this Balcones fault which is associated with the Ouachita front. This project is funded by a grant from the Norman Hackerman Advanced Research Program (NHARP), a biannual competition among Texas Universities to support research, and makes use of Texas Tech, Baylor, and UT Austin equipment. As a result, the deployment includes a less uniform array of seismic equipment, (10 Trillium compact seismometers and 10 Guralps; including 40Ts, 3Ts and 3ESPs), than projects supported by the IRIS PASSCAL center. Our vault construction was similar to Flexible array vaults, but Gulf Coast provides a more challenging environment for deployment than most encountered in the western US. The shallow water table and loose sediment can become almost fluid when storms deluge the area with rain. In dry periods, mud cracks near the vaults cause the vaults to tilt. As a result, even high quality, shallow seismic vaults can "float" or shift sufficiently to cause one or two components of the seismic stations to drift against their stops in days or weeks. As a result, the only data consistently available from all our stations, are vertical components. Horizontal component data from the summer of 2010 can be hit and miss due to the tilting of the vaults. These issues have been reduced in the summer of 2011 due to the drought. To address the data's shortcomings, we will average the vertical components from our stations and nearby EarthScope TA stations, (up 300 km away), to isolate the cleanest representation of the incoming P
Görges, Matthias; West, Nicholas C; Christopher, Nancy A; Koch, Jennifer L; Brodie, Sonia M; Lowlaavar, Nasim; Lauder, Gillian R; Ansermino, J Mark
2016-04-01
Respiratory depression in children receiving postoperative opioid infusions is a significant risk because of the interindividual variability in analgesic requirement. Detection of respiratory depression (or apnea) in these children may be improved with the introduction of automated acoustic respiratory rate (RR) monitoring. However, early detection of adverse events must be balanced with the risk of alarm fatigue. Our objective was to evaluate the use of acoustic RR monitoring in children receiving opioid infusions on a postsurgical ward and identify the causes of false alarm and optimal alarm thresholds. A video ethnographic study was performed using an observational, mixed methods approach. After surgery, an acoustic RR sensor was placed on the participant's neck and attached to a Rad87 monitor. The monitor was networked with paging for alarms. Vital signs data and paging notification logs were obtained from the central monitoring system. Webcam videos of the participant, infusion pump, and Rad87 monitor were recorded, stored on a secure server, and subsequently analyzed by 2 research nurses to identify the cause of the alarm, response, and effectiveness. Alarms occurring within a 90-second window were grouped into a single-alarm response opportunity. Data from 49 patients (30 females) with median age 14 (range, 4.4-18.8) years were analyzed. The 896 bedside vital sign threshold alarms resulted in 160 alarm response opportunities (44 low RR, 74 high RR, and 42 low SpO2). In 141 periods (88% of total), for which video was available, 65% of alarms were deemed effective (followed by an alarm-related action within 10 minutes). Nurses were the sole responders in 55% of effective alarms and the patient or parent in 20%. Episodes of desaturation (SpO2 < 90%) were observed in 9 patients: At the time of the SpO2 paging trigger, the RR was >10 bpm in 6 of 9 patients. Based on all RR samples observed, the default alarm thresholds, to serve as a starting point for each
NASA Astrophysics Data System (ADS)
Syed, Ahmed Rashid
Among the great physical challenges faced by the current front-end semiconductor equipment manufacturers is the accurate and repeatable surface temperature measurement of wafers during various fabrication steps. Close monitoring of temperature is essential in that it ensures desirable device characteristics to be reliably reproduced across various wafer lots. No where is the need to control temperature more pronounced than it is during Rapid Thermal Processing (RTP) which involves temperature ramp rates in excess of 200°C/s. This dissertation presents an elegant and practical approach to solve the wafer surface temperature estimation problem, in context of RTP, by deploying hardware that acquires the necessary data while preserving the integrity and purity of the wafer. In contrast to the widely used wafer-contacting (and hence contaminating) methods, such as bonded thermocouples, or environment sensitive schemes, such as light-pipes and infrared pyrometry, the proposed research explores the concept of utilizing Lamb (acoustic) waves to detect changes in wafer surface temperature, during RTP. Acoustic waves are transmitted to the wafer via an array of quartz rods that normally props the wafer inside an RTP chamber. These waves are generated using piezoelectric transducers affixed to the bases of the quartz rods. The group velocity of Lamb waves traversing the wafer surface undergoes a monotonic decrease with rise in wafer temperature. The correspondence of delay in phase of the received Lamb waves and the ambient temperature, along all direct paths between sending and receiving transducers, yields a psuedo real-time thermal image of the wafer. Although the custom built hardware-setup implements the above "proof-of-concept" scheme by transceiving acoustic signals at a single frequency, the real-world application will seek to enhance the data acquistion. rate (>1000 temperature measurements per seconds) by sending and receiving Lamb waves at multiple frequencies (by
MURI: Impact of Oceanographic Variability on Acoustic Communications
2012-09-30
ACSSC.2010.5757934 (2010). [published] [50] K. Tu, T.M. Duman, J.G. Proakis, and M. Stojanovic, “Cooperative MIMO - OFDM communications: Receiver...considered across bands of frequencies in the range 1-50 kHz. Multiple source and receiver cases ( MIMO ) will be of particular interest. Validating...Parabolic Equation (PE) acoustic models. Communication receiver design has included processors for orthogonal frequency division multiplexing ( OFDM
On Modeling Eavesdropping Attacks in Underwater Acoustic Sensor Networks †
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
Picosecond Acoustics in Single Quantum Wells of Cubic GaN /(Al ,Ga )N
NASA Astrophysics Data System (ADS)
Czerniuk, T.; Ehrlich, T.; Wecker, T.; As, D. J.; Yakovlev, D. R.; Akimov, A. V.; Bayer, M.
2017-01-01
A picosecond acoustic pulse is used to study the photoelastic interaction in single zinc-blende GaN /AlxGa1 -x N quantum wells. We use an optical time-resolved pump-probe setup and demonstrate that tuning the photon energy to the quantum well's lowest electron-hole transition makes the experiment sensitive to the quantum well only. Because of the small width, its temporal and spatial resolution allows us to track the few-picosecond-long transit of the acoustic pulse. We further deploy a model to analyze the unknown photoelastic coupling strength of the quantum well for different photon energies and find good agreement with the experiments.
Waveform inversion of acoustic waves for explosion yield estimation
Kim, K.; Rodgers, A. J.
2016-07-08
We present a new waveform inversion technique to estimate the energy of near-surface explosions using atmospheric acoustic waves. Conventional methods often employ air blast models based on a homogeneous atmosphere, where the acoustic wave propagation effects (e.g., refraction and diffraction) are not taken into account, and therefore, their accuracy decreases with increasing source-receiver distance. In this study, three-dimensional acoustic simulations are performed with a finite difference method in realistic atmospheres and topography, and the modeled acoustic Green's functions are incorporated into the waveform inversion for the acoustic source time functions. The strength of the acoustic source is related to explosionmore » yield based on a standard air blast model. The technique was applied to local explosions (<10 km) and provided reasonable yield estimates (<~30% error) in the presence of realistic topography and atmospheric structure. In conclusion, the presented method can be extended to explosions recorded at far distance provided proper meteorological specifications.« less
Waveform inversion of acoustic waves for explosion yield estimation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kim, K.; Rodgers, A. J.
We present a new waveform inversion technique to estimate the energy of near-surface explosions using atmospheric acoustic waves. Conventional methods often employ air blast models based on a homogeneous atmosphere, where the acoustic wave propagation effects (e.g., refraction and diffraction) are not taken into account, and therefore, their accuracy decreases with increasing source-receiver distance. In this study, three-dimensional acoustic simulations are performed with a finite difference method in realistic atmospheres and topography, and the modeled acoustic Green's functions are incorporated into the waveform inversion for the acoustic source time functions. The strength of the acoustic source is related to explosionmore » yield based on a standard air blast model. The technique was applied to local explosions (<10 km) and provided reasonable yield estimates (<~30% error) in the presence of realistic topography and atmospheric structure. In conclusion, the presented method can be extended to explosions recorded at far distance provided proper meteorological specifications.« less
Acoustic energy transmission in cast iron pipelines
NASA Astrophysics Data System (ADS)
Kiziroglou, Michail E.; Boyle, David E.; Wright, Steven W.; Yeatman, Eric M.
2015-12-01
In this paper we propose acoustic power transfer as a method for the remote powering of pipeline sensor nodes. A theoretical framework of acoustic power propagation in the ceramic transducers and the metal structures is drawn, based on the Mason equivalent circuit. The effect of mounting on the electrical response of piezoelectric transducers is studied experimentally. Using two identical transducer structures, power transmission of 0.33 mW through a 1 m long, 118 mm diameter cast iron pipe, with 8 mm wall thickness is demonstrated, at 1 V received voltage amplitude. A near-linear relationship between input and output voltage is observed. These results show that it is possible to deliver significant power to sensor nodes through acoustic waves in solid structures. The proposed method may enable the implementation of acoustic - powered wireless sensor nodes for structural and operation monitoring of pipeline infrastructure.
Capability 9.3 Assembly and Deployment
NASA Technical Reports Server (NTRS)
Dorsey, John
2005-01-01
Large space systems are required for a range of operational, commercial and scientific missions objectives however, current launch vehicle capacities substantially limit the size of space systems (on-orbit or planetary). Assembly and Deployment is the process of constructing a spacecraft or system from modules which may in turn have been constructed from sub-modules in a hierarchical fashion. In-situ assembly of space exploration vehicles and systems will require a broad range of operational capabilities, including: Component transfer and storage, fluid handling, construction and assembly, test and verification. Efficient execution of these functions will require supporting infrastructure, that can: Receive, store and protect (materials, components, etc.); hold and secure; position, align and control; deploy; connect/disconnect; construct; join; assemble/disassemble; dock/undock; and mate/demate.
Acoustic guide for noise-transmission testing of aircraft
NASA Technical Reports Server (NTRS)
Vaicaitis, Rimas (Inventor)
1987-01-01
Selective testing of aircraft or other vehicular components without requiring disassembly of the vehicle or components was accomplished by using a portable guide apparatus. The device consists of a broadband noise source, a guide to direct the acoustic energy, soft sealing insulation to seal the guide to the noise source and to the vehicle component, and noise measurement microphones, both outside the vehicle at the acoustic guide output and inside the vehicle to receive attenuated sound. By directing acoustic energy only to selected components of a vehicle via the acoustic guide, it is possible to test a specific component, such as a door or window, without picking up extraneous noise which may be transmitted to the vehicle interior through other components or structure. This effect is achieved because no acoustic energy strikes the vehicle exterior except at the selected component. Also, since the test component remains attached to the vehicle, component dynamics with vehicle frame are not altered.
Self-motion facilitates echo-acoustic orientation in humans
Wallmeier, Ludwig; Wiegrebe, Lutz
2014-01-01
The ability of blind humans to navigate complex environments through echolocation has received rapidly increasing scientific interest. However, technical limitations have precluded a formal quantification of the interplay between echolocation and self-motion. Here, we use a novel virtual echo-acoustic space technique to formally quantify the influence of self-motion on echo-acoustic orientation. We show that both the vestibular and proprioceptive components of self-motion contribute significantly to successful echo-acoustic orientation in humans: specifically, our results show that vestibular input induced by whole-body self-motion resolves orientation-dependent biases in echo-acoustic cues. Fast head motions, relative to the body, provide additional proprioceptive cues which allow subjects to effectively assess echo-acoustic space referenced against the body orientation. These psychophysical findings clearly demonstrate that human echolocation is well suited to drive precise locomotor adjustments. Our data shed new light on the sensory–motor interactions, and on possible optimization strategies underlying echolocation in humans. PMID:26064556
Innovative Acoustic Sensor Technologies for Leak Detection in Challenging Pipe Types
2016-12-30
consuming field surveys using sounders (listening sticks) that relied heavily upon operator skill or noise correlators that were tuned for finding leaks...installation and setup cost • Annual service fee Periodic Inspection Deployed in a “lift and shift” survey using acoustic cross- correlation ...the correlator , a zero reading is displayed and one of the sensors can be placed to evaluate the next pipe segment in the field survey . Table 2
Clinical Predictive Modeling Development and Deployment through FHIR Web Services.
Khalilia, Mohammed; Choi, Myung; Henderson, Amelia; Iyengar, Sneha; Braunstein, Mark; Sun, Jimeng
2015-01-01
Clinical predictive modeling involves two challenging tasks: model development and model deployment. In this paper we demonstrate a software architecture for developing and deploying clinical predictive models using web services via the Health Level 7 (HL7) Fast Healthcare Interoperability Resources (FHIR) standard. The services enable model development using electronic health records (EHRs) stored in OMOP CDM databases and model deployment for scoring individual patients through FHIR resources. The MIMIC2 ICU dataset and a synthetic outpatient dataset were transformed into OMOP CDM databases for predictive model development. The resulting predictive models are deployed as FHIR resources, which receive requests of patient information, perform prediction against the deployed predictive model and respond with prediction scores. To assess the practicality of this approach we evaluated the response and prediction time of the FHIR modeling web services. We found the system to be reasonably fast with one second total response time per patient prediction.
Clinical Predictive Modeling Development and Deployment through FHIR Web Services
Khalilia, Mohammed; Choi, Myung; Henderson, Amelia; Iyengar, Sneha; Braunstein, Mark; Sun, Jimeng
2015-01-01
Clinical predictive modeling involves two challenging tasks: model development and model deployment. In this paper we demonstrate a software architecture for developing and deploying clinical predictive models using web services via the Health Level 7 (HL7) Fast Healthcare Interoperability Resources (FHIR) standard. The services enable model development using electronic health records (EHRs) stored in OMOP CDM databases and model deployment for scoring individual patients through FHIR resources. The MIMIC2 ICU dataset and a synthetic outpatient dataset were transformed into OMOP CDM databases for predictive model development. The resulting predictive models are deployed as FHIR resources, which receive requests of patient information, perform prediction against the deployed predictive model and respond with prediction scores. To assess the practicality of this approach we evaluated the response and prediction time of the FHIR modeling web services. We found the system to be reasonably fast with one second total response time per patient prediction. PMID:26958207
Acoustic-sensor-based detection of damage in composite aircraft structures
NASA Astrophysics Data System (ADS)
Foote, Peter; Martin, Tony; Read, Ian
2004-03-01
Acoustic emission detection is a well-established method of locating and monitoring crack development in metal structures. The technique has been adapted to test facilities for non-destructive testing applications. Deployment as an operational or on-line automated damage detection technology in vehicles is posing greater challenges. A clear requirement of potential end-users of such systems is a level of automation capable of delivering low-level diagnosis information. The output from the system is in the form of "go", "no-go" indications of structural integrity or immediate maintenance actions. This level of automation requires significant data reduction and processing. This paper describes recent trials of acoustic emission detection technology for the diagnosis of damage in composite aerospace structures. The technology comprises low profile detection sensors using piezo electric wafers encapsulated in polymer film ad optical sensors. Sensors are bonded to the structure"s surface and enable acoustic events from the loaded structure to be located by triangulation. Instrumentation has been enveloped to capture and parameterise the sensor data in a form suitable for low-bandwidth storage and transmission.
Modelling and Order of Acoustic Transfer Functions Due to Reflections from Augmented Objects
NASA Astrophysics Data System (ADS)
Kuster, Martin; de Vries, Diemer
2006-12-01
It is commonly accepted that the sound reflections from real physical objects are much more complicated than what usually is and can be modelled by room acoustics modelling software. The main reason for this limitation is the level of detail inherent in the physical object in terms of its geometrical and acoustic properties. In the present paper, the complexity of the sound reflections from a corridor wall is investigated by modelling the corresponding acoustic transfer functions at several receiver positions in front of the wall. The complexity for different wall configurations has been examined and the changes have been achieved by altering its acoustic image. The results show that for a homogenous flat wall, the complexity is significant and for a wall including various smaller objects, the complexity is highly dependent on the position of the receiver with respect to the objects.
Gasc, Amandine; Sueur, Jérôme; Pavoine, Sandrine; Pellens, Roseli; Grandcolas, Philippe
2013-01-01
New Caledonia is a Pacific island with a unique biodiversity showing an extreme microendemism. Many species distributions observed on this island are extremely restricted, localized to mountains or rivers making biodiversity evaluation and conservation a difficult task. A rapid biodiversity assessment method based on acoustics was recently proposed. This method could help to document the unique spatial structure observed in New Caledonia. Here, this method was applied in an attempt to reveal differences among three mountain sites (Mandjélia, Koghis and Aoupinié) with similar ecological features and species richness level, but with high beta diversity according to different microendemic assemblages. In each site, several local acoustic communities were sampled with audio recorders. An automatic acoustic sampling was run on these three sites for a period of 82 successive days. Acoustic properties of animal communities were analysed without any species identification. A frequency spectral complexity index (NP) was used as an estimate of the level of acoustic activity and a frequency spectral dissimilarity index (Df) assessed acoustic differences between pairs of recordings. As expected, the index NP did not reveal significant differences in the acoustic activity level between the three sites. However, the acoustic variability estimated by the index Df, could first be explained by changes in the acoustic communities along the 24-hour cycle and second by acoustic dissimilarities between the three sites. The results support the hypothesis that global acoustic analyses can detect acoustic differences between sites with similar species richness and similar ecological context, but with different species assemblages. This study also demonstrates that global acoustic methods applied at broad spatial and temporal scales could help to assess local biodiversity in the challenging context of microendemism. The method could be deployed over large areas, and could help to compare
Gasc, Amandine; Sueur, Jérôme; Pavoine, Sandrine; Pellens, Roseli; Grandcolas, Philippe
2013-01-01
New Caledonia is a Pacific island with a unique biodiversity showing an extreme microendemism. Many species distributions observed on this island are extremely restricted, localized to mountains or rivers making biodiversity evaluation and conservation a difficult task. A rapid biodiversity assessment method based on acoustics was recently proposed. This method could help to document the unique spatial structure observed in New Caledonia. Here, this method was applied in an attempt to reveal differences among three mountain sites (Mandjélia, Koghis and Aoupinié) with similar ecological features and species richness level, but with high beta diversity according to different microendemic assemblages. In each site, several local acoustic communities were sampled with audio recorders. An automatic acoustic sampling was run on these three sites for a period of 82 successive days. Acoustic properties of animal communities were analysed without any species identification. A frequency spectral complexity index (NP) was used as an estimate of the level of acoustic activity and a frequency spectral dissimilarity index (Df ) assessed acoustic differences between pairs of recordings. As expected, the index NP did not reveal significant differences in the acoustic activity level between the three sites. However, the acoustic variability estimated by the index Df , could first be explained by changes in the acoustic communities along the 24-hour cycle and second by acoustic dissimilarities between the three sites. The results support the hypothesis that global acoustic analyses can detect acoustic differences between sites with similar species richness and similar ecological context, but with different species assemblages. This study also demonstrates that global acoustic methods applied at broad spatial and temporal scales could help to assess local biodiversity in the challenging context of microendemism. The method could be deployed over large areas, and could help to
Observation of seafloor crustal movement using the seafloor acoustic ranging on Kumano-nada
NASA Astrophysics Data System (ADS)
Osada, Y.; Kido, M.; Fujimoto, H.
2010-12-01
Along the Nankai Trough, where the Philippine Sea plate subducts under southeastern Japan with a convergence rate of about 65 mm/yr, large interplate thrust earthquakes of magnitude 8 class have occurred repeatedly with recurrence intervals of 100-200 years. About 60 years have passed since the last earthquakes happened in 1944 and 1946. Therefore it is important to monitor the tectonic activities in the Nankai Trough. Since most of the source region of the earthquakes is located beneath the ocean, an observation system is necessary in the offshore source region. We developed a seafloor acoustic ranging system to continuously monitor the seafloor crustal movement. We aim to monitor the activity in the splay faults in the rupture area of the Tonankai earthquake in the Nankai subduction zone. Slips along the active splay faults may be an important mechanism that the elastic strain caused by relative plate motion. We carried out two experiments, a short-term (one day) and a long-term (four month) experiments, to estimate the repeatability of acoustic measurements of this system. We deployed four PXPs (precision acoustic transponders) with about 600 m (M2-S1 baseline) and 920 m (M2-S2 base line) spacing in the long-term experiment. The standard deviation in acoustic measurements was about 1 cm on each baseline. In September 2008 we carried out an observation to monitor an active splay faults on Kumano-Nada prism slope. We deployed three PXPs with about 925 m (M1-S2 baseline) and 725 m (M1-S2 base line) spacing at the depth of some 2880 m. We recovered them in August 2010 to get data of acoustic measurements for 6 month and pressure measurements for 18 month. The round trip travel time shows a variation with peak-to-peak amplitude of about 1msec. We preliminarily collected the time series of round trip travel times using sound speed, which was estimated from measured temperature and pressure, and attitude data. We discuss the result of a variation of distance.
Hydroxyapatite cement cranioplasty in translabyrinthine acoustic neuroma surgery.
Arriaga, Moisês A; Chen, Douglas A
2002-05-01
Hydroxyapatite cement cranioplasty (HAC) after translabyrinthine resection of acoustic neuroma is a promising new technique for wound reconstruction. This study reviews the efficacy of HAC for the prevention of cerebrospinal fluid (CSF) leakage and the long-term wound outcomes of HAC versus abdominal fat graft (AFG) reconstruction. This retrospective study of l08 consecutive acoustic neuromas operated on by Pittsburgh Ear Associates uses chart review, telephone interview, and mail questionnaire data. Fifty-four patients received AFG dural repair, and 54 patients received HAC. Seven AFG patients (12.5%) had CSF leaks versus 2 (3.7%) of the overall group of 54 HAC patients. However, none (0%) of the 47 HAC patients had CSF leakage with current HAC techniques. HAC also produced significantly less postauricular wound depression and superior cosmetic results in comparison with AFG. Although HAC patients experienced less postoperative discomfort, wound complications requiring medical or surgical intervention were extremely uncommon in both groups. HAC offers significant CSF leakage control and long-term cosmetic and comfort advantages over AFG alone. We recommend HAC as the standard closure technique for translabyrinthine acoustic neuroma surgery.
Solid surface wetting and the deployment of drops in microgravity
NASA Technical Reports Server (NTRS)
Trinh, E. H.; Depew, J.
1994-01-01
The complete or partial deployment of liquid samples in low gravity is primarily influenced by the interfacial properties of the specific liquid and solid materials used because the overwhelming bias of the Earth gravitational acceleration is removed. This study addresses the engineering aspects of injecting and deploying drops of prescribed volume into an acoustic positioning chamber in microgravity. The specific problems of interest are the design, testing, and implementation of injector tips to be used in a simultaneously retracting dual-injector system in the Drop Physics Module microgravity experiment facility. Prior to release, the liquid to be deployed must be retained within a restricted area at the very end of the injectors under dynamic stimuli from the continuous injection flow as well as from the stepped motion of the injectors. The final released drop must have a well determined volume and negligible residual linear or angular momentum. The outcome of Earth-based short-duration low gravity experiments had been the selection of two types of injector tips which were flown as back-up parts. They were successfully utilized during the USML-1 Spacelab mission as the primary tips. The combination of a larger contact surface, liquid pinning with a sharp edge, and selective coating of strategic tip surfaces with a non-wetting compound has allowed a significant increase in the success rate of deployment of simple and compound drops of aqueous solutions of glycerol and silicone oil. The diameter of the samples studied in the Drop Physics Module range between 0.3 and 2.7 cm. The tests conducted on-orbit with a manually operated small device have allowed the calibration of the volume deployed for a few drop sizes. The design for improved tips to be used during the next USML flight is based on these results.
Sensitivity analyses of acoustic impedance inversion with full-waveform inversion
NASA Astrophysics Data System (ADS)
Yao, Gang; da Silva, Nuno V.; Wu, Di
2018-04-01
Acoustic impedance estimation has a significant importance to seismic exploration. In this paper, we use full-waveform inversion to recover the impedance from seismic data, and analyze the sensitivity of the acoustic impedance with respect to the source-receiver offset of seismic data and to the initial velocity model. We parameterize the acoustic wave equation with velocity and impedance, and demonstrate three key aspects of acoustic impedance inversion. First, short-offset data are most suitable for acoustic impedance inversion. Second, acoustic impedance inversion is more compatible with the data generated by density contrasts than velocity contrasts. Finally, acoustic impedance inversion requires the starting velocity model to be very accurate for achieving a high-quality inversion. Based upon these observations, we propose a workflow for acoustic impedance inversion as: (1) building a background velocity model with travel-time tomography or reflection waveform inversion; (2) recovering the intermediate wavelength components of the velocity model with full-waveform inversion constrained by Gardner’s relation; (3) inverting the high-resolution acoustic impedance model with short-offset data through full-waveform inversion. We verify this workflow by the synthetic tests based on the Marmousi model.
Martin, S.J.; Ricco, A.J.
1993-08-10
A chemical or intrinsic physical property sensor is described comprising: (a) a substrate; (b) an interaction region of said substrate where the presence of a chemical or physical stimulus causes a detectable change in the velocity and/or an attenuation of an acoustic wave traversing said region; and (c) a plurality of paired input and output interdigitated electrodes patterned on the surface of said substrate where each of said paired electrodes has a distinct periodicity, where each of said paired electrodes is comprised of an input and an output electrode; (d) an input signal generation means for transmitting an input signal having a distinct frequency to a specified input interdigitated electrode of said plurality so that each input electrode receives a unique input signal, whereby said electrode responds to said input signal by generating an acoustic wave of a specified frequency, thus, said plurality responds by generating a plurality of acoustic waves of different frequencies; (e) an output signal receiving means for determining an acoustic wave velocity and an amplitude of said acoustic waves at several frequencies after said waves transverses said interaction region and comparing these values to an input acoustic wave velocity and an input acoustic wave amplitude to produce values for perturbations in acoustic wave velocities and for acoustic wave attenuation as a function of frequency, where said output receiving means is individually coupled to each of said output interdigitated electrode; (f) a computer means for analyzing a data stream comprising information from said output receiving means and from said input signal generation means to differentiate a specified response due to a perturbation from a subsequent specified response due to a subsequent perturbation to determine the chemical or intrinsic physical properties desired.
Application of an ultrasonic focusing radiator for acoustic levitation of submillimeter samples
NASA Technical Reports Server (NTRS)
Lee, M. C.
1981-01-01
An acoustic apparatus has been specifically developed to handle samples of submillimeter size in a gaseous medium. This apparatus consists of an acoustic levitation device, deployment devices for small liquid and solid samples, heat sources for sample heat treatment, acoustic alignment devices, a cooling system and data-acquisition instrumentation. The levitation device includes a spherical aluminum dish of 12 in. diameter and 0.6 in. thickness, 130 pieces of PZT transducers attached to the back side of the dish and a spherical concave reflector situated in the vicinity of the center of curvature of the dish. The three lowest operating frequencies for the focusing-radiator levitation device are 75, 105 and 163 kHz, respectively. In comparison with other levitation apparatus, it possesses a large radiation pressure and a high lateral positional stability. This apparatus can be used most advantageously in the study of droplets and spherical shell systems, for instance, for fusion target applications.
A comparison of sampling methods for a standing tree acoustic device
Jerry M. Mahon, Jr.; Lewis Jordan; Lawrence R. Schimleck; Alexander Clark, III; Richard F. Daniels
2009-01-01
One method of evaluating potential product performance is the use of acoustic tools for identifying trees with high stiffness. Acoustic velocities for 100 standing loblolly pine (Pinus taeda) trees, obtained with the transmitting and receiving probes placed on the same face and opposite faces, were compared. Significant differences in velocity between the two...
Acoustic Propagation Modeling for Marine Hydro-Kinetic Applications
NASA Astrophysics Data System (ADS)
Johnson, C. N.; Johnson, E.
2014-12-01
The combination of riverine, tidal, and wave energy have the potential to supply over one third of the United States' annual electricity demand. However, in order to deploy and test prototypes, and commercial installations, marine hydrokinetic (MHK) devices must meet strict regulatory guidelines that determine the maximum amount of noise that can be generated and sets particular thresholds for determining disturbance and injury caused by noise. An accurate model for predicting the propagation of a MHK source in a real-life hydro-acoustic environment has been established. This model will help promote the growth and viability of marine, water, and hydrokinetic energy by confidently assuring federal regulations are meet and harmful impacts to marine fish and wildlife are minimal. Paracousti, a finite difference solution to the acoustic equations, was originally developed for sound propagation in atmospheric environments and has been successfully validated for a number of different geophysical activities. The three-dimensional numerical implementation is advantageous over other acoustic propagation techniques for a MHK application where the domains of interest have complex 3D interactions from the seabed, banks, and other shallow water effects. A number of different cases for hydro-acoustic environments have been validated by both analytical and numerical results from canonical and benchmark problems. This includes a variety of hydrodynamic and physical environments that may be present in a potential MHK application including shallow and deep water, sloping, and canyon type bottoms, with varying sound speed and density profiles. With the model successfully validated for hydro-acoustic environments more complex and realistic MHK sources from turbines and/or arrays can be modeled.
Heinemann, M; Larraza, A; Smith, K B
2003-06-01
The most difficult problem in shallow underwater acoustic communications is considered to be the time-varying multipath propagation because it impacts negatively on data rates. At high data rates the intersymbol interference requires adaptive algorithms on the receiver side that lead to computationally intensive and complex signal processing. A novel technique called time-reversal acoustics (TRA) can environmentally adapt the acoustic propagation effects of a complex medium in order to focus energy at a particular target range and depth. Using TRA, the multipath structure is reduced because all the propagation paths add coherently at the intended target location. This property of time-reversal acoustics suggests a potential application in the field of noncoherent acoustic communications. This work presents results of a tank scale experiment using an algorithm for rapid transmission of binary data in a complex underwater environment with the TRA approach. A simple 15-symbol code provides an example of the simplicity and feasibility of the approach. Covert coding due to the inherent scrambling induced by the environment at points other than the intended receiver is also investigated. The experiments described suggest a high potential in data rate for the time-reversal approach in underwater acoustic communications while keeping the computational complexity low.
Spacecraft on-orbit deployment anomalies - What can be done?
NASA Astrophysics Data System (ADS)
Freeman, Michael T.
1993-04-01
Modern communications satellites rely heavily upon deployable appendage (i.e. solar arrays, communications antennas, etc.) to perform vital functions that enable the spacecraft to effectively conduct mission objectives. Communications and telemetry antennas provide the radiofrequency link between the spacecraft and the earth ground station, permitting data to be transmitted and received from the satellite. Solar arrays serve as the principle source of electrical energy to the satellite, and recharge internal batteries during operation. However, since satellites cannot carry backup systems, if a solar array fails to deploy, the mission is lost. This article examines the subject of on-orbit anomalies related to the deployment of spacecraft appendage, and possible causes of such failures. Topics discussed shall include mechanical launch loading, on-orbit thermal and solar concerns, reliability of spacecraft pyrotechnics, and practical limitations of ground-based deployment testing. Of particular significance, the article will feature an in-depth look at the lessons learned from the successful recovery of the Telesat Canada Anik-E2 satellite in 1991.
Heart rate variability: Pre-deployment predictor of post-deployment PTSD symptoms
Pyne, Jeffrey M.; Constans, Joseph I.; Wiederhold, Mark D.; Gibson, Douglas P.; Kimbrell, Timothy; Kramer, Teresa L.; Pitcock, Jeffery A.; Han, Xiaotong; Williams, D. Keith; Chartrand, Don; Gevirtz, Richard N.; Spira, James; Wiederhold, Brenda K.; McCraty, Rollin; McCune, Thomas R.
2017-01-01
Heart rate variability is a physiological measure associated with autonomic nervous system activity. This study hypothesized that lower pre-deployment HRV would be associated with higher post-deployment post-traumatic stress disorder (PTSD) symptoms. Three-hundred-forty-three Army National Guard soldiers enrolled in the Warriors Achieving Resilience (WAR) study were analyzed. The primary outcome was PTSD symptom severity using the PTSD Checklist – Military version (PCL) measured at baseline, 3- and 12-month post-deployment. Heart rate variability predictor variables included: high frequency power (HF) and standard deviation of the normal cardiac inter-beat interval (SDNN). Generalized linear mixed models revealed that the pre-deployment PCL*ln(HF) interaction term was significant (p < 0.0001). Pre-deployment SDNN was not a significant predictor of post-deployment PCL. Covariates included age, pre-deployment PCL, race/ethnicity, marital status, tobacco use, childhood abuse, pre-deployment traumatic brain injury, and previous combat zone deployment. Pre-deployment heart rate variability predicts post-deployment PTSD symptoms in the context of higher pre-deployment PCL scores. PMID:27773678
Field tests of acoustic telemetry for a portable coastal observatory
Martini, M.; Butman, B.; Ware, J.; Frye, D.
2006-01-01
Long-term field tests of a low-cost acoustic telemetry system were carried out at two sites in Massachusetts Bay. At each site, an acoustic Doppler current profiler mounted on a bottom tripod was fitted with an acoustic modem to transmit data to a surface buoy; electronics mounted on the buoy relayed these data to shore via radio modem. The mooring at one site (24 m water depth) was custom-designed for the telemetry application, with a custom designed small buoy, a flexible electro-mechanical buoy to mooring joint using a molded chain connection to the buoy, quick-release electro-mechanical couplings, and dual hydrophones suspended 7 m above the bottom. The surface buoy at the second site (33 m water depth) was a U.S. Coast Guard (USCG) channel buoy fitted with telemetry electronics and clamps to hold the hydrophones. The telemetry was tested in several configurations for a period of about four years. The custom-designed buoy and mooring provided nearly error-free data transmission through the acoustic link under a variety of oceanographic conditions for 261 days at the 24 m site. The electro mechanical joint, cables and couplings required minimal servicing and were very reliable, lasting 862 days deployed before needing repairs. The acoustic communication results from the USCG buoy were poor, apparently due to the hard cobble bottom, noise from the all-steel buoy, and failure of the hydrophone assembly. Access to the USCG buoy at sea required ideal weather. ??2006 IEEE.
Non-Data Aided Doppler Shift Estimation for Underwater Acoustic Communication
2014-05-01
in underwater acoustic wireless sensor networks . We analyzed the data collected from our experiments using non-data aided (blind) techniques such as...investigated different methods for blind Doppler shift estimation and compensation for a single carrier in underwater acoustic wireless sensor ...distributed underwater sensor networks . Detailed experimental and simulated results based on second order cyclostationary features of the received signals
Acoustic communication in insect disease vectors
Vigoder, Felipe de Mello; Ritchie, Michael Gordon; Gibson, Gabriella; Peixoto, Alexandre Afranio
2013-01-01
Acoustic signalling has been extensively studied in insect species, which has led to a better understanding of sexual communication, sexual selection and modes of speciation. The significance of acoustic signals for a blood-sucking insect was first reported in the XIX century by Christopher Johnston, studying the hearing organs of mosquitoes, but has received relatively little attention in other disease vectors until recently. Acoustic signals are often associated with mating behaviour and sexual selection and changes in signalling can lead to rapid evolutionary divergence and may ultimately contribute to the process of speciation. Songs can also have implications for the success of novel methods of disease control such as determining the mating competitiveness of modified insects used for mass-release control programs. Species-specific sound “signatures” may help identify incipient species within species complexes that may be of epidemiological significance, e.g. of higher vectorial capacity, thereby enabling the application of more focussed control measures to optimise the reduction of pathogen transmission. Although the study of acoustic communication in insect vectors has been relatively limited, this review of research demonstrates their value as models for understanding both the functional and evolutionary significance of acoustic communication in insects. PMID:24473800
NASA Astrophysics Data System (ADS)
Wang, Delin
In this thesis, we develop the basics of the Passive Ocean Acoustic Waveguide Remote Sensing (POAWRS) technique for the instantaneous continental-shelf scale detection, localization and species classification of marine mammal vocalizations. POAWRS uses a large-aperture, densely sampled coherent hydrophone array system with orders of magnitude higher array gain to enhance signal-to-noise ratios (SNR) by coherent beamforming, enabling detection of underwater acoustic signals either two orders of magnitude more distant in range or lower in SNR than a single hydrophone. The ability to employ coherent spatial processing of signals with the POAWRS technology significantly improves areal coverage, enabling detection of oceanic sound sources over instantaneous wide areas spanning 100 km or more in diameter. The POAWRS approach was applied to analyze marine mammal vocalizations from diverse species received on a 160-element Office Naval Research Five Octave Research Array (ONR-FORA) deployed during their feeding season in Fall 2006 in the Gulf of Maine. The species-dependent temporal-spatial distribution of marine mammal vocalizations and correlation to the prey fish distributions have been determined. Furthermore, the probability of detection regions, source level distributions and pulse compression gains of the vocalization signals from diverse marine mammal species have been estimated. We also develop an approach for enhancing the angular resolution and improving bearing estimates of acoustic signals received on a coherent hydrophone array with multiple-nested uniformly-spaced subapertures, such as the ONR-FORA, by nonuniform array beamforming. Finally we develop a low-cost non-oil-filled towable prototype hydrophone array that consists of eight hydrophone elements with real-time data acquisition and 100 m tow cable. The approach demonstrated here will be applied in the development of a full 160 element POAWRS-type low-cost coherent hydrophone array system in the future.
Development of High Data Rate Acoustic Multiple-Input/Multiple-Output Modems
2015-09-30
communication capabilities of underwater platforms and facilitate real-time adaptive operations in the ocean. OBJECTIVES The ...signaling at the transmitter and low-complexity time reversal processing at the receiver. APPROACH Underwater acoustic (UWA) communication is useful...digital communications in shallow water environments. The advancement has direct impacts on defense appliations since underwater acoustic modems
Active Hearing Mechanisms Inspire Adaptive Amplification in an Acoustic Sensor System.
Guerreiro, Jose; Reid, Andrew; Jackson, Joseph C; Windmill, James F C
2018-06-01
Over many millions of years of evolution, nature has developed some of the most adaptable sensors and sensory systems possible, capable of sensing, conditioning and processing signals in a very power- and size-effective manner. By looking into biological sensors and systems as a source of inspiration, this paper presents the study of a bioinspired concept of signal processing at the sensor level. By exploiting a feedback control mechanism between a front-end acoustic receiver and back-end neuronal based computation, a nonlinear amplification with hysteretic behavior is created. Moreover, the transient response of the front-end acoustic receiver can also be controlled and enhanced. A theoretical model is proposed and the concept is prototyped experimentally through an embedded system setup that can provide dynamic adaptations of a sensory system comprising a MEMS microphone placed in a closed-loop feedback system. It faithfully mimics the mosquito's active hearing response as a function of the input sound intensity. This is an adaptive acoustic sensor system concept that can be exploited by sensor and system designers within acoustics and ultrasonic engineering fields.
USDOT guidance summary for connected vehicle deployments : application deployment.
DOT National Transportation Integrated Search
2016-07-01
This document provides guidance material in regards to the Application Deployment Plan for the CV Pilots DeploymentConcept Development Phase. Methods for application deployment are discussed with definitions for the successfulmanagement of each aspec...
On resonant coupling of acoustic waves and gravity waves
NASA Astrophysics Data System (ADS)
Millet, Christophe
2017-11-01
Acoustic propagation in the atmosphere is often modeled using modes that are confined within waveguides causing the sound to propagate through multiple paths to the receiver. On the other hand, direct observations in the lower stratosphere show that the gravity wave field is intermittent, and is often dominated by rather well defined large-amplitude wave packets. In the present work, we use normal modes to describe both the gravity wave field and the acoustic field. The gravity wave spectrum is obtained by launching few monochromatic waves whose properties are chosen stochastically to mimic the intermittency. Owing to the disparity of the gravity and acoustic length scales, the interactions between the gravity wave field and each of the acoustic modes can be described using a multiple-scale analysis. The appropriate amplitude evolution equation for the acoustic field involves certain random terms that can be directly related to the gravity wave sources. We will show that the cumulative effect of gravity wave breakings makes the sensitivity of ground-based acoustic signals large, in that small changes in the gravity wave parameterization can create or destroy specific acoustic features.
Design of a seismo-acoustic station for Antarctica.
Contrafatto, Danilo; Fasone, Rosario; Ferro, Angelo; Larocca, Graziano; Laudani, Giuseppe; Rapisarda, Salvatore; Scuderi, Luciano; Zuccarello, Luciano; Privitera, Eugenio; Cannata, Andrea
2018-04-01
In recent years, seismological studies in Antarctica have contributed plenty of new knowledge in many fields of earth science. Moreover, acoustic investigations are now also considered a powerful tool that provides insights for many different objectives, such as analyses of regional climate-related changes and studies of volcanic degassing and explosive activities. However, installation and maintenance of scientific instrumentation in Antarctica can be really challenging. Indeed, the instruments have to face the most extreme climate on the planet. They must be tolerant of very low temperatures and robust enough to survive strong winds. Moreover, one of the most critical tasks is powering a remote system year-round at polar latitudes. In this work, we present a novel seismo-acoustic station designed to work reliably in polar regions. To enable year-round seismo-acoustic data collection in such a remote, extreme environment, a hybrid powering system is used, integrating solar panels, a wind generator, and batteries. A power management system was specifically developed to either charge the battery bank or divert energy surplus to warm the enclosure or release the excess energy to the outside environment. Finally, due to the prohibitive environmental conditions at most Antarctic installation sites, the station was designed to be deployed quickly.
Design of a seismo-acoustic station for Antarctica
NASA Astrophysics Data System (ADS)
Contrafatto, Danilo; Fasone, Rosario; Ferro, Angelo; Larocca, Graziano; Laudani, Giuseppe; Rapisarda, Salvatore; Scuderi, Luciano; Zuccarello, Luciano; Privitera, Eugenio; Cannata, Andrea
2018-04-01
In recent years, seismological studies in Antarctica have contributed plenty of new knowledge in many fields of earth science. Moreover, acoustic investigations are now also considered a powerful tool that provides insights for many different objectives, such as analyses of regional climate-related changes and studies of volcanic degassing and explosive activities. However, installation and maintenance of scientific instrumentation in Antarctica can be really challenging. Indeed, the instruments have to face the most extreme climate on the planet. They must be tolerant of very low temperatures and robust enough to survive strong winds. Moreover, one of the most critical tasks is powering a remote system year-round at polar latitudes. In this work, we present a novel seismo-acoustic station designed to work reliably in polar regions. To enable year-round seismo-acoustic data collection in such a remote, extreme environment, a hybrid powering system is used, integrating solar panels, a wind generator, and batteries. A power management system was specifically developed to either charge the battery bank or divert energy surplus to warm the enclosure or release the excess energy to the outside environment. Finally, due to the prohibitive environmental conditions at most Antarctic installation sites, the station was designed to be deployed quickly.
USDOT guidance summary for connected vehicle deployments : deployment outreach.
DOT National Transportation Integrated Search
2016-07-01
This document provides guidance material in regards to the outreach activities in the CV Pilot Deployment ConceptDevelopment Phase and deployment outreach plan in the Deployment Phases. This guidance provides keyrequirements and references in develop...
Willatzen, M
1999-01-01
A general set of modeling equations for lossless one-dimensional multilayer ultrasound transducers is presented based on first principles. In particular, a direct relationship between ultrasound transducer results and the underlying physical principles of electroacoustics is given. As such, the model may provide better physical understanding for designers not fully versed in electrical circuits theory or in linear system analyses. The model is suitable for time-domain analysis and monofrequency design. Special attention is given to the determination of the time-dependent voltage across the receiver electrodes subject to a general voltage input, but information on any (dynamic) variable of interest is provided. The basic equations governing the dynamics of the multilayer structure acting as transmitter as well as receiver are solved by Fourier analysis and by imposing continuity of velocity and pressure between layers. Sound transmission between the two piezoelectric circuits is assumed to take place in a water bath such that the Rayleigh equation can be used to obtain the incoming pressure at the receiver aperture from the acceleration of the opposing transmitter aperture. Comparison with experimental results is possible by allowing coupling to external electric impedances. A numerical test case using a multilayered 1-MHz transducer for flow meter applications was considered and good agreement with experiments was obtained in terms of voltage signals. The transducer contains a half-wavelength stainless steel layer needed to resist corrosion, the ability to operate at temperatures in a wide range from 20 to 150 degrees Celsius, resistance to impact from flowing particles in the medium, high pressure or vacuum, and pH values up to 10 in some locations. The influence of epoxy glue and grease acoustic coupling layers-between the piezoceramics and the stainless steel layer-in the range from 1 to 70 mum was examined. It was shown that, for the same layer thickness, epoxy
Exposure to seismic survey alters blue whale acoustic communication
Di Iorio, Lucia; Clark, Christopher W.
2010-01-01
The ability to perceive biologically important sounds is critical to marine mammals, and acoustic disturbance through human-generated noise can interfere with their natural functions. Sounds from seismic surveys are intense and have peak frequency bands overlapping those used by baleen whales, but evidence of interference with baleen whale acoustic communication is sparse. Here we investigated whether blue whales (Balaenoptera musculus) changed their vocal behaviour during a seismic survey that deployed a low-medium power technology (sparker). We found that blue whales called consistently more on seismic exploration days than on non-exploration days as well as during periods within a seismic survey day when the sparker was operating. This increase was observed for the discrete, audible calls that are emitted during social encounters and feeding. This response presumably represents a compensatory behaviour to the elevated ambient noise from seismic survey operations. PMID:19776059
Micrometeoroid and Lunar Secondary Ejecta Flux Measurements: Comparison of Three Acoustic Systems
NASA Technical Reports Server (NTRS)
Corsaro, R. D.; Giovane, F.; Liou, Jer-Chyi; Burtchell, M.; Pisacane, V.; Lagakos, N.; Williams, E.; Stansbery, E.
2010-01-01
This report examines the inherent capability of three large-area acoustic sensor systems and their applicability for micrometeoroids (MM) and lunar secondary ejecta (SE) detection and characterization for future lunar exploration activities. Discussion is limited to instruments that can be fabricated and deployed with low resource requirements. Previously deployed impact detection probes typically have instrumented capture areas less than 0.2 square meters. Since the particle flux decreases rapidly with increased particle size, such small-area sensors rarely encounter particles in the size range above 50 microns, and even their sampling the population above 10 microns is typically limited. Characterizing the sparse dust population in the size range above 50 microns requires a very large-area capture instrument. However it is also important that such an instrument simultaneously measures the population of the smaller particles, so as to provide a complete instantaneous snapshot of the population. For lunar or planetary surface studies, the system constraints are significant. The instrument must be as large as possible to sample the population of the largest MM. This is needed to reliably assess the particle impact risks and to develop cost-effective shielding designs for habitats, astronauts, and critical instrument. The instrument should also have very high sensitivity to measure the flux of small and slow SE particles. is the SE environment is currently poorly characterized, and possess a contamination risk to machinery and personnel involved in exploration. Deployment also requires that the instrument add very little additional mass to the spacecraft. Three acoustic systems are being explored for this application.
Development of pre-deployment primary healthcare training for Combat Medical Technicians.
Parsons, Iain T; Rawden, M P; Wheatley, R J
2014-09-01
To develop and run a primary healthcare (PHC) refresher package to address the range of clinical presentations to Combat Medical Technicians (CMTs) on deployment and improve their confidence and capability in providing PHC for Op Herrick 18, with particular regard to the first month of deployment. A regimental level, two-and-a-half day refresher package was developed following analysis of PHC conditions most likely to be seen on Op HERRICK 18. It consisted of lectures and skill stations with written and case-based assessment phases to demonstrate effective and safe use of CMT clinical protocols on simulated patients. Internal feedback assessed the CMT's subjective understanding of each individual section. A qualitative questionnaire was used to retrospectively evaluate the package after 1 month of deployment. Immediate feedback showed that the refresher training was well received. Following the first month of deployment, CMTs who had attended the PHC refresher package felt more confident in managing PHC patients and felt they had received training for the majority of PHC conditions witnessed during their deployment in comparison with CMTs who had not. By delivering a training package acceptable to the majority of medics, we have increased the confidence and capability of CMTs in delivering PHC within the context of their protocols and prepared them for their first month of deployment. It suggests that PHC delivery can be improved by such a package and consideration should be given to formalising this into a military training qualification. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Acoustic monitoring of coastal dolphins and their response to naval mine neutralization exercises
Howe, Marian; Zang, Eden; McElligott, Megan; Engelhaupt, Amy; Munger, Lisa
2017-01-01
To investigate the potential impacts of naval mine neutralization exercises (MINEX) on odontocete cetaceans, a long-term passive acoustic monitoring study was conducted at a US Navy training range near Virginia Beach, USA. Bottom-moored acoustic recorders were deployed in 2012–2016 near the epicentre of MINEX training activity and were refurbished every 2–4 months. Recordings were analysed for the daily presence/absence of dolphins, and dolphin acoustic activity was quantified in detail for the hours and days before and after 31 MINEX training events. Dolphins occurred in the area year-round, but there was clear seasonal variability, with lower presence during winter months. Dolphins exhibited a behavioural response to underwater detonations. Dolphin acoustic activity near the training location was lower during the hours and days following detonations, suggesting that animals left the area and/or reduced their signalling. Concurrent acoustic monitoring farther away from the training area suggested that the radius of response was between 3 and 6 km. A generalized additive model indicated that the predictors that explained the greatest amount of deviance in the data were the day relative to the training event, the hour of the day and circumstances specific to each training event. PMID:29308219
Acoustic monitoring of coastal dolphins and their response to naval mine neutralization exercises.
Lammers, Marc O; Howe, Marian; Zang, Eden; McElligott, Megan; Engelhaupt, Amy; Munger, Lisa
2017-12-01
To investigate the potential impacts of naval mine neutralization exercises (MINEX) on odontocete cetaceans, a long-term passive acoustic monitoring study was conducted at a US Navy training range near Virginia Beach, USA. Bottom-moored acoustic recorders were deployed in 2012-2016 near the epicentre of MINEX training activity and were refurbished every 2-4 months. Recordings were analysed for the daily presence/absence of dolphins, and dolphin acoustic activity was quantified in detail for the hours and days before and after 31 MINEX training events. Dolphins occurred in the area year-round, but there was clear seasonal variability, with lower presence during winter months. Dolphins exhibited a behavioural response to underwater detonations. Dolphin acoustic activity near the training location was lower during the hours and days following detonations, suggesting that animals left the area and/or reduced their signalling. Concurrent acoustic monitoring farther away from the training area suggested that the radius of response was between 3 and 6 km. A generalized additive model indicated that the predictors that explained the greatest amount of deviance in the data were the day relative to the training event, the hour of the day and circumstances specific to each training event.
Analytic model for ultrasound energy receivers and their optimal electric loads
NASA Astrophysics Data System (ADS)
Gorostiaga, M.; Wapler, M. C.; Wallrabe, U.
2017-08-01
In this paper, we present an analytic model for thickness resonating plate ultrasound energy receivers, which we have derived from the piezoelectric and the wave equations and, in which we have included dielectric, viscosity and acoustic attenuation losses. Afterwards, we explore the optimal electric load predictions by the zero reflection and power maximization approaches present in the literature with different acoustic boundary conditions, and discuss their limitations. To validate our model, we compared our expressions with the KLM model solved numerically with very good agreement. Finally, we discuss the differences between the zero reflection and power maximization optimal electric loads, which start to differ as losses in the receiver increase.
Smart Acoustic Network Using Combined FSK-PSK, Adaptive Beamforming and Equalization
2002-09-30
sonar data transmission from underwater vehicle during mission. The two-year objectives for the high-reliability acoustic network using multiple... sonar laboratory) and used for acoustic networking during underwater vehicle operation. The joint adaptive coherent path beamformer method consists...broadband communications transducer, while the low noise preamplifier conditions received signals for analog to digital conversion. External user
Smart Acoustic Network Using Combined FSK-PSK, Adaptive, Beamforming and Equalization
2001-09-30
sonar data transmission from underwater vehicle during mission. The two-year objectives for the high-reliability acoustic network using multiple... sonar laboratory) and used for acoustic networking during underwater vehicle operation. The joint adaptive coherent path beamformer method consists...broadband communications transducer, while the low noise preamplifier conditions received signals for analog to digital conversion. External user
Single- and multi-channel underwater acoustic communication channel capacity: a computational study.
Hayward, Thomas J; Yang, T C
2007-09-01
Acoustic communication channel capacity determines the maximum data rate that can be supported by an acoustic channel for a given source power and source/receiver configuration. In this paper, broadband acoustic propagation modeling is applied to estimate the channel capacity for a time-invariant shallow-water waveguide for a single source-receiver pair and for vertical source and receiver arrays. Without bandwidth constraints, estimated single-input, single-output (SISO) capacities approach 10 megabitss at 1 km range, but beyond 2 km range they decay at a rate consistent with previous estimates by Peloquin and Leinhos (unpublished, 1997), which were based on a sonar equation calculation. Channel capacities subject to source bandwidth constraints are approximately 30-90% lower than for the unconstrained case, and exhibit a significant wind speed dependence. Channel capacity is investigated for single-input, multi-output (SIMO) and multi-input, multi-output (MIMO) systems, both for finite arrays and in the limit of a dense array spanning the entire water column. The limiting values of the SIMO and MIMO channel capacities for the modeled environment are found to be about four times higher and up to 200-400 times higher, respectively, than for the SISO case. Implications for underwater acoustic communication systems are discussed.
Design and Evaluation of a Scalable and Reconfigurable Multi-Platform System for Acoustic Imaging
Izquierdo, Alberto; Villacorta, Juan José; del Val Puente, Lara; Suárez, Luis
2016-01-01
This paper proposes a scalable and multi-platform framework for signal acquisition and processing, which allows for the generation of acoustic images using planar arrays of MEMS (Micro-Electro-Mechanical Systems) microphones with low development and deployment costs. Acoustic characterization of MEMS sensors was performed, and the beam pattern of a module, based on an 8 × 8 planar array and of several clusters of modules, was obtained. A flexible framework, formed by an FPGA, an embedded processor, a computer desktop, and a graphic processing unit, was defined. The processing times of the algorithms used to obtain the acoustic images, including signal processing and wideband beamforming via FFT, were evaluated in each subsystem of the framework. Based on this analysis, three frameworks are proposed, defined by the specific subsystems used and the algorithms shared. Finally, a set of acoustic images obtained from sound reflected from a person are presented as a case study in the field of biometric identification. These results reveal the feasibility of the proposed system. PMID:27727174
Acoustically induced oscillation and rotation of a large drop in space
NASA Astrophysics Data System (ADS)
Jacobi, N.; Croonquist, A. P.; Elleman, D. D.; Wang, T. G.
1982-03-01
A 2.5 cm diameter water drop was successfully deployed and manipulated in a triaxial acoustic resonance chamber during a 240 sec low-gravity SPAR rocket flight. Oscillation and rotation were induced by modulating and phase shifting the signals to the speakers. Portions of the film record were digitized and analyzed. Spectral analysis brought out the n = 2, 3, 4 free oscillation modes of the drop, its very low-frequency center-of-mass motion in the acoustic potential well, and the forced oscillation frequency. The drop boundaries were least-square fitted to general ellipses, providing eccentricities of the distorted drop. The normalized equatorial area of the rotating drop was plotted vs a rotational parameter, and was in excellent agreement with values derived from the theory of equilibrium shapes of rotating liquid drops.
Method for distinguishing multiple targets using time-reversal acoustics
Berryman, James G.
2004-06-29
A method for distinguishing multiple targets using time-reversal acoustics. Time-reversal acoustics uses an iterative process to determine the optimum signal for locating a strongly reflecting target in a cluttered environment. An acoustic array sends a signal into a medium, and then receives the returned/reflected signal. This returned/reflected signal is then time-reversed and sent back into the medium again, and again, until the signal being sent and received is no longer changing. At that point, the array has isolated the largest eigenvalue/eigenvector combination and has effectively determined the location of a single target in the medium (the one that is most strongly reflecting). After the largest eigenvalue/eigenvector combination has been determined, to determine the location of other targets, instead of sending back the same signals, the method sends back these time reversed signals, but half of them will also be reversed in sign. There are various possibilities for choosing which half to do sign reversal. The most obvious choice is to reverse every other one in a linear array, or as in a checkerboard pattern in 2D. Then, a new send/receive, send-time reversed/receive iteration can proceed. Often, the first iteration in this sequence will be close to the desired signal from a second target. In some cases, orthogonalization procedures must be implemented to assure the returned signals are in fact orthogonal to the first eigenvector found.
Wireless acoustic-electric feed-through for power and signal transmission
NASA Technical Reports Server (NTRS)
Doty, Benjamin (Inventor); Badescu, Mircea (Inventor); Sherrit, Stewart (Inventor); Bao, Xiaoqi (Inventor); Bar-Cohen, Yoseph (Inventor); Chang, Zensheu (Inventor)
2011-01-01
An embodiment provides electrical energy from a source on one side of a medium to a load on the other side of the medium, the embodiment including a first piezoelectric to generate acoustic energy in response to electrical energy from the source, and a second piezoelectric to convert the received acoustic energy to electrical energy used by the load. Other embodiments are described and claimed.
New OBS network deployment offshore Ireland
NASA Astrophysics Data System (ADS)
Le Pape, Florian; Bean, Chris; Craig, David; Jousset, Philippe; Horan, Clare; Hogg, Colin; Donne, Sarah; McCann, Hannah; Möllhoff, Martin; Kirk, Henning; Ploetz, Aline
2016-04-01
With the presence of the stormy NE Atlantic, Ireland is ideally located to investigate further our understanding of ocean generated microseisms and use noise correlation methods to develop seismic imaging in marine environments as well as time-lapse monitoring. In order to study the microseismic activity offshore Ireland, 10 Broad Band Ocean Bottom Seismographs (OBSs) units including hydrophones have been deployed in January 2016 across the shelf offshore Donegal and out into the Rockall Trough. This survey represents the first Broadband passive study in this part of the NE Atlantic. The instruments will be recovered in August 2016 providing 8 months worth of data to study microseisms but also the offshore seismic activity in the area. One of the main goal of the survey is to investigate the spatial and temporal distributions of dominant microseism source regions, close to the microseism sources. Additionally we will study the coupling of seismic and acoustic signals at the sea bed and its evolution in both the deep water and continental shelf areas. Furthermore, the survey also aims to investigate further the relationship between sea state conditions (e.g. wave height, period), seafloor pressure variations and seismic data recorded on both land and seafloor. Finally, the deployed OBS network is also the first ever attempt to closely monitor local offshore earthquakes in Ireland. Ireland seismicity although relatively low can reduce slope stability and poses the possibility of triggering large offshore landslides and local tsunamis.
Folegot, Thomas; Martinelli, Giovanna; Guerrini, Piero; Stevenson, J Mark
2008-11-01
An algorithm allowing simultaneous detection and localization of multiple submerged targets crossing an acoustic tripwire based on forward scattering is described and then evaluated based upon data collected at sea. This paper quantifies the agreement between the theoretical performance and the results obtained from processing data gathered at sea for crossings at several depths and ranges. Targets crossing the acoustic field produce shadows on each side of the barrier, for specific sensors and for specific acoustic paths. In post-processing, a model is invoked to associate expected paths with the observed shadows. This process allows triangulation of the target's position inside the acoustic field. Precise localization is achieved by taking advantage of the multipath propagation structure of the received signal, together with the diversity of the source and receiver locations. Environmental robustness is demonstrated using simulations and can be explained by the use of an array of sources spatially distributed through the water column.
Ursano, Robert J; Wang, Jing; Fullerton, Carol S; Ramsawh, Holly; Gifford, Robert K; Russell, Dale; Cohen, Gregory H; Sampson, Laura; Galea, Sandro
2018-01-01
Given the greater prevalence of post-deployment mental health concerns among reservists, the higher likelihood of deploying without their regular unit, and potentially lower rates of deployment preparedness, we examined associations between deploying with or without one's regular unit (individual augmentee status, IAS), deployment preparedness, and mental health problems including post-traumatic stress disorder (PTSD), depression (MDD), and binge drinking in a nationally representative sample of Reserve Component (RC) Army and Marine-enlisted males (n = 705). A series of multivariate regressions examined the association of mental health with IAS and deployment preparedness, adjusting for demographics. To examine whether deployment preparedness varied by IAS, an IAS × deployment preparedness interaction was included. In an adjusted model, being an individual augmentee and low deployment preparedness were associated with any mental health problem (screening positive for PTSD, MDD, binge drinking, or any combination of the three). There was a significant IAS × deployment preparedness interaction. Mental health problems did not vary by preparedness among individual augmentees. Participants deploying with regular units with low-medium preparedness had greater risk for mental health problems (odds ratio [OR] = 3.69, 95% confidence interval [CI] = 1.78-7.62 and OR = 2.29, 95% CI = 1.12-4.71), than those with high preparedness. RC-enlisted male personnel who deployed without their regular unit were five times more likely to have a mental health problem, and were 61% more likely to report binge drinking. Additionally, those with lower levels of deployment preparedness were up to three times more likely to have a mental health problem and up to six times more likely to report PTSD. The current investigation found that both IAS and deployment preparedness were associated with negative mental health outcomes in a large representative sample of previously deployed RC
2015-09-30
an AUV mounted acoustic source, 2) moored multi-element SHRU acoustic receiver arrays, 3) a shipboard acoustic resonator, 4) fish-attraction...devices (FAD’s), 5) a three- AUV fish-field mapping effort (employing sidescan sonar plus optics) and 6) ScanFish, ADCP, and moored sensor oceanographic...The acoustic model has been further refined. To obtain a better estimate of source positions, the navigation data of the source AUV (Snoopy) was
Acoustically Driven Fluid and Particle Motion in Confined and Leaky Systems
NASA Astrophysics Data System (ADS)
Barnkob, Rune; Nama, Nitesh; Ren, Liqiang; Huang, Tony Jun; Costanzo, Francesco; Kähler, Christian J.
2018-01-01
The acoustic motion of fluids and particles in confined and acoustically leaky systems is receiving increasing attention for its use in medicine and biotechnology. A number of contradicting physical and numerical models currently exist, but their validity is uncertain due to the unavailability of hard-to-access experimental data for validation. We provide experimental benchmarking data by measuring 3D particle trajectories and demonstrate that the particle trajectories can be described numerically without any fitting parameter by a reduced-fluid model with leaky impedance-wall conditions. The results reveal the hitherto unknown existence of a pseudo-standing wave that drives the acoustic streaming as well as the acoustic radiation force on suspended particles.
Passive Wake Acoustics Measurements at Denver International Airport
NASA Technical Reports Server (NTRS)
Wang, Frank Y.; Wassaf, Hadi; Dougherty, Robert P.; Clark, Kevin; Gulsrud, Andrew; Fenichel, Neil; Bryant, Wayne H.
2004-01-01
From August to September 2003, NASA conducted an extensive measurement campaign to characterize the acoustic signal of wake vortices. A large, both spatially as well as in number of elements, phased microphone array was deployed at Denver International Airport for this effort. This paper will briefly describe the program background, the microphone array, as well as the supporting ground-truth and meteorological sensor suite. Sample results to date are then presented and discussed. It is seen that, in the frequency range processed so far, wake noise is generated predominantly from a very confined area around the cores.
Acoustic microscope surface inspection system and method
Khuri-Yakub, Butrus T.; Parent, Philippe; Reinholdtsen, Paul A.
1991-01-01
An acoustic microscope surface inspection system and method in which pulses of high frequency electrical energy are applied to a transducer which forms and focuses acoustic energy onto a selected location on the surface of an object and receives energy from the location and generates electrical pulses. The phase of the high frequency electrical signal pulses are stepped with respected to the phase of a reference signal at said location. An output signal is generated which is indicative of the surface of said selected location. The object is scanned to provide output signals representative of the surface at a plurality of surface locations.
Assessing the acoustical climate of underground stations.
Nowicka, Elzbieta
2007-01-01
Designing a proper acoustical environment--indispensable to speech recognition--in long enclosures is difficult. Although there is some literature on the acoustical conditions in underground stations, there is still little information about methods that make estimation of correct reverberation conditions possible. This paper discusses the assessment of the reverberation conditions of underground stations. A comparison of the measurements of reverberation time in Warsaw's underground stations with calculated data proves there are divergences between measured and calculated early decay time values, especially for long source-receiver distances. Rapid speech transmission index values for measured stations are also presented.
APL - North Pacific Acoustic Laboratory
2011-09-01
including marine mammals ) measurements in the NE Pacific Ocean. The Laboratory consists of the legacy SOSUS hydrophone receiver network in the...exposure in the marine environment. Philippine Sea- Ambient noise levels measured during the 2010-2011 Philippine Sea experiment on the Scripps...sound speed perturbations and the characteristics of the ambient acoustic noise field. Scattering and diffraction resulting from internal waves and
Thode, Aaron; Straley, Janice; Tiemann, Christopher O; Folkert, Kendall; O'Connell, Victoria
2007-08-01
Sperm whales (Physeter macrocephalus) have learned to remove fish from demersal longline gear deployments off the eastern Gulf of Alaska, and are often observed to arrive at a site after a haul begins, suggesting a response to potential acoustic cues like fishing-gear strum, hydraulic winch tones, and propeller cavitation. Passive acoustic recorders attached to anchorlines have permitted continuous monitoring of the ambient noise environment before and during fishing hauls. Timing and tracking analyses of sperm whale acoustic activity during three encounters indicate that cavitation arising from changes in ship propeller speeds is associated with interruptions in nearby sperm whale dive cycles and changes in acoustically derived positions. This conclusion has been tested by cycling a vessel engine and noting the arrival of whales by the vessel, even when the vessel is not next to fishing gear. No evidence of response from activation of ship hydraulics or fishing gear strum has been found to date.
NASA Astrophysics Data System (ADS)
Gaura, Elena; Roedig, Utz; Brusey, James
2010-12-01
modalities and (iv) system solutions with high end-user added value and cost benefits. The common thread is deployment and deployment evaluation. In particular, satisfaction of application requirements, involvement of the end-user in the design and deployment process, satisfactory system performance and user acceptance are concerns addressed in many of the contributions. The contributions form a valuable set, which help to identify the priorities for research in this burgeoning area: Robust, reliable and efficient data collection in embedded wireless multi-hop networks are essential elements in creating a true deploy-and-forget user experience. Maintaining full connectivity within a WSN, in a real world environment populated by other WSNs, WiFi networks or Bluetooth devices that constitute sources of interference is a key element in any application, but more so for those that are safety-critical, such as disaster response. Awareness of the effects of wireless channel, physical position and line-of-sight on received signal strength in real-world, outdoor environments will shape the design of many outdoor applications. Thus, the quantification of such effects is valuable knowledge for designers. Sensors' failure detection, scalability and commercialization are common challenges in many long-term monitoring applications; transferable solutions are evidenced here in the context of pollutant detection and water quality. Innovative, alternative thinking is often needed to achieve the desired long-lived networks when power-hungry sensors are foreseen components; in some instances, the very problems of wireless technology, such as RF irregularity, can be transformed into advantages. The importance of an iterative design and evaluation methodology—from analysis to simulation to real-life deployment—should be well understood by all WSN developers. The value of this is highlighted in the context of a challenging WPAN video-surveillance application based on a novel Nomadic Access
Range-dependence of acoustic channel with traveling sinusoidal surface wave.
Choo, Youngmin; Seong, Woojae; Lee, Keunhwa
2014-04-01
Range-dependence of time-varying acoustic channels caused by a traveling surface wave is investigated through water tank experiments and acoustic propagation analysis schemes. As the surface wave travels, surface reflected signals fluctuate and the fluctuation varies with source-receiver horizontal range. Amplitude fluctuations of surface reflected signals increase with increasing horizontal range whereas the opposite occurs in delay fluctuations. The scattered pressure field at a fixed time shows strong dependence on the receiver position because of caustics and shadow zones formed by the surface. The Doppler shifts of surface reflected signals also depend on the horizontal range. Comparison between measurement data and model results indicates the Doppler shift relies on the delay fluctuation under current experimental conditions.
DOT National Transportation Integrated Search
2016-08-04
This document is the Task 7 Application Deployment Plan deliverable for the New York City Connected Vehicle Pilot Deployment. It describes the process that the deployment team will follow to acquire and test the connected vehicle safety applications....
Diversity of acoustic tracheal system and its role for directional hearing in crickets
2013-01-01
Background Sound localization in small insects can be a challenging task due to physical constraints in deriving sufficiently large interaural intensity differences (IIDs) between both ears. In crickets, sound source localization is achieved by a complex type of pressure difference receiver consisting of four potential sound inputs. Sound acts on the external side of two tympana but additionally reaches the internal tympanal surface via two external sound entrances. Conduction of internal sound is realized by the anatomical arrangement of connecting trachea. A key structure is a trachea coupling both ears which is characterized by an enlarged part in its midline (i.e., the acoustic vesicle) accompanied with a thin membrane (septum). This facilitates directional sensitivity despite an unfavorable relationship between wavelength of sound and body size. Here we studied the morphological differences of the acoustic tracheal system in 40 cricket species (Gryllidae, Mogoplistidae) and species of outgroup taxa (Gryllotalpidae, Rhaphidophoridae, Gryllacrididae) of the suborder Ensifera comprising hearing and non hearing species. Results We found a surprisingly high variation of acoustic tracheal systems and almost all investigated species using intraspecific acoustic communication were characterized by an acoustic vesicle associated with a medial septum. The relative size of the acoustic vesicle - a structure most crucial for deriving high IIDs - implies an important role for sound localization. Most remarkable in this respect was the size difference of the acoustic vesicle between species; those with a more unfavorable ratio of body size to sound wavelength tend to exhibit a larger acoustic vesicle. On the other hand, secondary loss of acoustic signaling was nearly exclusively associated with the absence of both acoustic vesicle and septum. Conclusion The high diversity of acoustic tracheal morphology observed between species might reflect different steps in the evolution
Design and first tests of an acoustic positioning and detection system for KM3NeT
NASA Astrophysics Data System (ADS)
Simeone, F.; Ameli, F.; Ardid, M.; Bertin, V.; Bonori, M.; Bou-Cabo, M.; Calì, C.; D'Amico, A.; Giovanetti, G.; Imbesi, M.; Keller, P.; Larosa, G.; Llorens, C. D.; Masullo, R.; Randazzo, N.; Riccobene, G.; Speziale, F.; Viola, S.; KM3NeT Consortium
2012-01-01
In a deep-sea neutrino telescope it is mandatory to locate the position of the optical sensors with a precision of about 10 cm. To achieve this requirement, an innovative Acoustic Positioning System (APS) has been designed in the frame work of the KM3NeT neutrino telescope. The system will also be able to provide an acoustic guide during the deployment of the telescope’s components and seafloor infrastructures (junction boxes, cables, etc.). A prototype of the system based on the successful acoustic systems of ANTARES and NEMO is being developed. It will consist of an array of hydrophones and a network of acoustic transceivers forming the Long Baseline. All sensors are connected to the telescope data acquisition system and are in phase and synchronised with the telescope master clock. Data from the acoustic sensors, continuously sampled at 192 kHz, will be sent to shore where signal recognition and analysis will be carried out. The design and first tests of the system elements will be presented. This new APS is expected to have better precision compared to the systems used in ANTARES and NEMO, and can also be used as a real-time monitor of acoustic sources and environmental noise in deep sea.
2014-08-01
Service women in the U.S. Armed Forces face unique challenges that may lead to or exacerbate gynecologic disorders - particularly during deployment. This report documented that approximately one in 10 military women who served in Southwest/Central Asia were diagnosed with a gynecologic disorder at least once during deployment. In addition, gynecologic disorders accounted for approximately one of every 20 medical evacuations of female service members from the war zone. A majority of clinically significant gynecologic disorder cases were attributable to irregular menstruation/bleeding or unspecified inflammation or pain of the female genital organs. Incidence rates of gynecologic disorder diagnoses were higher among black, non-Hispanic service women, among younger women, and among those in the Army and in motor transport and communications/intelligence occupations. Approximately 50% of gynecologic disorder cases had received gynecologic care within 6 months prior to deployment and nearly 90% had received care within 2 years of deployment. Despite pre-deployment care, it is apparent from this report that service women need continuous access to gynecologic care during deployment, particularly if conditions during deployment lead to and exacerbate gynecologic disorders.
Identifying individual sperm whales acoustically using self-organizing maps
NASA Astrophysics Data System (ADS)
Ioup, Juliette W.; Ioup, George E.
2005-09-01
The Littoral Acoustic Demonstration Center (LADC) is a consortium at Stennis Space Center comprising the University of New Orleans, the University of Southern Mississippi, the Naval Research Laboratory, and the University of Louisiana at Lafayette. LADC deployed three Environmental Acoustic Recording System (EARS) buoys in the northern Gulf of Mexico during the summer of 2001 to study ambient noise and marine mammals. Each LADC EARS was an autonomous, self-recording buoy capable of 36 days of continuous recording of a single channel at an 11.7-kHz sampling rate (bandwidth to 5859 Hz). The hydrophone selected for this analysis was approximately 50 m from the bottom in a water depth of 800 m on the continental slope off the Mississippi River delta. This paper contains recent analysis results for sperm whale codas recorded during a 3-min period. Results are presented for the identification of individual sperm whales from their codas, using the acoustic properties of the clicks within each coda. The recorded time series, the Fourier transform magnitude, and the wavelet transform coefficients are each used separately with a self-organizing map procedure for 43 codas. All show the codas as coming from four or five individual whales. [Research supported by ONR.
Resonant acoustic transducer and driver system for a well drilling string communication system
Chanson, Gary J.; Nicolson, Alexander M.
1981-01-01
The acoustic data communication system includes an acoustic transmitter and receiver wherein low frequency acoustic waves, propagating in relatively loss free manner in well drilling string piping, are efficiently coupled to the drill string and propagate at levels competitive with the levels of noise generated by drilling machinery also present in the drill string. The transmitting transducer incorporates a mass-spring piezoelectric transmitter and amplifier combination that permits self-oscillating resonant operation in the desired low frequency range.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Harding, Samuel F.; Sellar, Brian; Richmond, Marshall C.
An array of single-beam acoustic Doppler profilers has been developed for the high resolution measurement of three-dimensional tidal flow velocities and subsequently tested in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use divergent acoustic beams emanating from a single instrument. This is achieved using geometrically convergent acoustic beams creating a sample volume at the focal point of 0.03 m3. Away from the focal point, the array is also able to simultaneously reconstruct three-dimensional velocity components in a profile throughout the watermore » column, and is referred to herein as a convergent-beam acoustic Doppler profiler (C-ADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational commercial-scale Alstom 1MW DeepGen-IV Tidal Turbine deployed at the European Marine Energy Center, Orkney Isles, UK. This proof-of-concept paper outlines the C-ADP system configuration and comparison to measurements provided by co-installed reference instrumentation.« less
Ecological Insights from Pelagic Habitats Acquired Using Active Acoustic Techniques.
Benoit-Bird, Kelly J; Lawson, Gareth L
2016-01-01
Marine pelagic ecosystems present fascinating opportunities for ecological investigation but pose important methodological challenges for sampling. Active acoustic techniques involve producing sound and receiving signals from organisms and other water column sources, offering the benefit of high spatial and temporal resolution and, via integration into different platforms, the ability to make measurements spanning a range of spatial and temporal scales. As a consequence, a variety of questions concerning the ecology of pelagic systems lend themselves to active acoustics, ranging from organism-level investigations and physiological responses to the environment to ecosystem-level studies and climate. As technologies and data analysis methods have matured, the use of acoustics in ecological studies has grown rapidly. We explore the continued role of active acoustics in addressing questions concerning life in the ocean, highlight creative applications to key ecological themes ranging from physiology and behavior to biogeography and climate, and discuss emerging avenues where acoustics can help determine how pelagic ecosystems function.
Method of Adjusting Acoustic Impedances for Impedance-Tunable Acoustic Segments
NASA Technical Reports Server (NTRS)
Jones, Kennie H (Inventor); Nark, Douglas M. (Inventor); Jones, Michael G. (Inventor); Parrott, Tony L. (Inventor); Lodding, Kenneth N. (Inventor)
2012-01-01
A method is provided for making localized decisions and taking localized actions to achieve a global solution. In an embodiment of the present invention, acoustic impedances for impedance-tunable acoustic segments are adjusted. A first acoustic segment through an N-th acoustic segment are defined. To start the process, the first acoustic segment is designated as a leader and a noise-reducing impedance is determined therefor. This is accomplished using (i) one or more metrics associated with the acoustic wave at the leader, and (ii) the metric(s) associated with the acoustic wave at the N-th acoustic segment. The leader, the N-th acoustic segment, and each of the acoustic segments exclusive of the leader and the N-th acoustic segment, are tuned to the noise-reducing impedance. The current leader is then excluded from subsequent processing steps. The designation of leader is then given one of the remaining acoustic segments, and the process is repeated for each of the acoustic segments through an (N-1)-th one of the acoustic segments.
Pre-deployment Year Mental Health Diagnoses and Treatment in Deployed Army Women
Adams, Rachel Sayko; Mohr, Beth A.; Jeffery, Diana D.; Funk, Wendy; Williams, Thomas V.; Larson, Mary Jo
2016-01-01
We estimated the prevalence of select mental health diagnoses (MHDX) and mental health treatment (MHT), and identified characteristics associated with MHT during the pre-deployment year (365 days before deployment) in active duty Army women (N = 14,633) who returned from Iraq or Afghanistan deployments in FY2010. Pre-deployment year prevalence estimates were: 26.2 % for any select MHDX and 18.1 % for any MHT. Army women who had physical injuries since FY2002 or any behavioral health treatment between FY2002 and the pre-deployment year had increased odds of pre-deployment year MHT. During the pre-deployment year, a substantial percentage of Army women had MHDX and at least one MHT encounter or stay. Future research should determine if pre-deployment MHDX among Army women reflect vulnerability to future MHDX, or if pre-deployment MHT results in protection from chronic symptoms. PMID:27368233
Pre-deployment Year Mental Health Diagnoses and Treatment in Deployed Army Women.
Wooten, Nikki R; Adams, Rachel Sayko; Mohr, Beth A; Jeffery, Diana D; Funk, Wendy; Williams, Thomas V; Larson, Mary Jo
2017-07-01
We estimated the prevalence of select mental health diagnoses (MHDX) and mental health treatment (MHT), and identified characteristics associated with MHT during the pre-deployment year (365 days before deployment) in active duty Army women (N = 14,633) who returned from Iraq or Afghanistan deployments in FY2010. Pre-deployment year prevalence estimates were: 26.2 % for any select MHDX and 18.1 % for any MHT. Army women who had physical injuries since FY2002 or any behavioral health treatment between FY2002 and the pre-deployment year had increased odds of pre-deployment year MHT. During the pre-deployment year, a substantial percentage of Army women had MHDX and at least one MHT encounter or stay. Future research should determine if pre-deployment MHDX among Army women reflect vulnerability to future MHDX, or if pre-deployment MHT results in protection from chronic symptoms.
Passive acoustic records of two vigorous bubble-plume methane seeps on the Oregon continental margin
NASA Astrophysics Data System (ADS)
Dziak, R. P.; Matsumoto, H.; Merle, S. G.; Embley, R. W.; Baumberger, T.; Hammond, S. R.
2016-12-01
We present preliminary analysis of the acoustic records of two bubble-plume methane seeps recorded by an autonomous hydrophone deployed during the E/V Nautilus expedition (NA072) in June 2016. The goal of the NA072 expedition was to use the Simrad 302 as a survey tool to map bubble plumes at a regional scale along the Oregon and northern California margins, followed by in situ investigation of bubble-plume sites using the ROV Hercules. The exploration carried out during NA072 resulted in the discovery of hundreds of new individual methane seep sites in water depths ranging from 125 to 1725 m depth. A Greenridge Acousonde 3B™ hydrophone was deployed via ROV within two vigorous bubble-plume sites. Despite persistent ship and ROV propeller noise, the acoustic signature of the bubble-plume can be seen in the hydrophone record as a broadband (0.5 - 4.5 kHz) series of short duration ( 0.2-0.5 msec) pulses that occur in clusters of dozens of pulses lasting 2-3 secs. Previous studies of the passive acoustics of seep bubble-plumes indicate sound is generated during bubble formation, where detachment of the gas bubble from the end of a tube or conduit causes the bubble to oscillate, producing sound. The peak frequency f (the zeroth oscillatory mode) and the bubble equivalent spherical radius r for a given pressure P are: f = (2πr)-1 [(3γP/ρ)]1/2 where γ is the ratio of gas specific heat at constant pressure to constant volume and ρ is the water density (Leifer and Tang, 2006). Thus the frequency of a bubble's oscillation is proportional to the bubble's volume, and therefore it may be possible to use our acoustic data to obtain an estimate of the volume of methane being released at these seafloor plume sites.
Translational illusion of acoustic sources by transformation acoustics.
Sun, Fei; Li, Shichao; He, Sailing
2017-09-01
An acoustic illusion of creating a translated acoustic source is designed by utilizing transformation acoustics. An acoustic source shifter (ASS) composed of layered acoustic metamaterials is designed to achieve such an illusion. A practical example where the ASS is made with naturally available materials is also given. Numerical simulations verify the performance of the proposed device. The designed ASS may have some applications in, e.g., anti-sonar detection.
Joint Estimation of Source Range and Depth Using a Bottom-Deployed Vertical Line Array in Deep Water
Li, Hui; Yang, Kunde; Duan, Rui; Lei, Zhixiong
2017-01-01
This paper presents a joint estimation method of source range and depth using a bottom-deployed vertical line array (VLA). The method utilizes the information on the arrival angle of direct (D) path in space domain and the interference characteristic of D and surface-reflected (SR) paths in frequency domain. The former is related to a ray tracing technique to backpropagate the rays and produces an ambiguity surface of source range. The latter utilizes Lloyd’s mirror principle to obtain an ambiguity surface of source depth. The acoustic transmission duct is the well-known reliable acoustic path (RAP). The ambiguity surface of the combined estimation is a dimensionless ad hoc function. Numerical efficiency and experimental verification show that the proposed method is a good candidate for initial coarse estimation of source position. PMID:28590442
REVEAL: Receiver Exploiting Variability in Estimated Acoustic Levels
2013-08-07
water . Several structures have been or are being investigated. In shallow water , passive sonar context, the characteristics of received signals are...source, particularly in shallow water . Several structures have been or are being investigated. In shallow water , passive sonar context, the... dynamic and variable in time and space, a statistical approach is necessary. WORK COMPLETED In a shallow water waveguide, where the distance
The seasonal occupancy and diel behaviour of Antarctic sperm whales revealed by acoustic monitoring.
Miller, Brian S; Miller, Elanor J
2018-04-03
The seasonal occupancy and diel behaviour of sperm whales (Physeter macrocephalus) was investigated using data from long-term acoustic recorders deployed off east Antarctica. An automated method for investigating acoustic presence of sperm whales was developed, characterised, and applied to multi-year acoustic datasets at three locations. Instead of focusing on the acoustic properties of detected clicks, the method relied solely on the inter-click-interval (ICI) for determining presence within an hour-long recording. Parameters for our classifier were informed by knowledge of typical vocal behaviour of sperm whales. Sperm whales were detected predominantly from Dec-Feb, occasionally in Nov, Mar, Apr, and May, but never in the Austral winter or early spring months. Ice cover was found to have a statistically significant negative effect on sperm whale presence. In ice-free months sperm whales were detected more often during daylight hours and were seldom detected at night, and this effect was also statistically significant. Seasonal presence at the three east Antarctic recording sites were in accord with what has been inferred from 20th century whale catches off western Antarctica and from stomach contents of whales caught off South Africa.
Golden Gate National Recreation Area : acoustical monitoring 2007/2008
DOT National Transportation Integrated Search
2011-03-01
In 2007, the Natural Sounds Program (NPS) received a technical assistance request to collect baseline acoustical data at Golden Gate National Recreation Area (GGNRA). During the summer (June September 2007) and winter (January February 2008),...
2011-09-30
channel interference mitigation for underwater acoustic MIMO - OFDM . 3) Turbo equalization for OFDM modulated physical layer network coding. 4) Blind CFO...Underwater Acoustic MIMO - OFDM . MIMO - OFDM has been actively studied for high data rate communications over the bandwidthlimited underwater acoustic...with the cochannel interference (CCI) due to parallel transmissions in MIMO - OFDM . Our proposed receiver has the following components: 1
Turgut, Altan; Orr, Marshall; Pasewark, Bruce
2007-05-01
Waveguide invariant theory is used to describe the frequency shifts of constant acoustic intensity level curves in broadband signal spectrograms measured at the New Jersey Shelf during the winter of 2003. The broadband signals (270-330 Hz) were transmitted from a fixed source and received at three fixed receivers, located at 10, 20, and 30 km range along a cross-shelf propagation track. The constant acoustic intensity level curves of the received signals indicate regular frequency shifts that can be well predicted by the change in water depth observed through tens of tidal cycles. A second pattern of frequency shifts is observed at only 30 km range where significant variability of slope-water intrusion was measured. An excellent agreement between observed frequency shifts of the constant acoustic intensity levels and those predicted by the change in tide height and slope water elevations suggests the capability of long-term acoustic monitoring of tide and slope water intrusions in winter conditions.
A Unified Approach to Passive and Active Ocean Acoustic Waveguide Remote Sensing
2012-09-30
acoustic sensing reveals humpback whale behavior synchronous with herring spawning processes and sonar had no effect on humpback song ,” submitted to...source and receiver arrays to enable instantaneous continental-shelf scale imaging and continuous monitoring of fish and whale populations. Acoustic...Preliminary analysis shows that humpback whale behavior is synchronous with peak annual Atlantic herring spawning processes in the Gulf of
Acoustic multipath arrivals in the horizontal plane due to approaching nonlinear internal waves.
Badiey, Mohsen; Katsnelson, Boris G; Lin, Ying-Tsong; Lynch, James F
2011-04-01
Simultaneous measurements of acoustic wave transmissions and a nonlinear internal wave packet approaching an along-shelf acoustic path during the Shallow Water 2006 experiment are reported. The incoming internal wave packet acts as a moving frontal layer reflecting (or refracting) sound in the horizontal plane. Received acoustic signals are filtered into acoustic normal mode arrivals. It is shown that a horizontal multipath interference is produced. This has previously been called a horizontal Lloyd's mirror. The interference between the direct path and the refracted path depends on the mode number and frequency of the acoustic signal. A mechanism for the multipath interference is shown. Preliminary modeling results of this dynamic interaction using vertical modes and horizontal parabolic equation models are in good agreement with the observed data.
Acoustic microscope surface inspection system and method
Khuri-Yakub, B.T.; Parent, P.; Reinholdtsen, P.A.
1991-02-26
An acoustic microscope surface inspection system and method are described in which pulses of high frequency electrical energy are applied to a transducer which forms and focuses acoustic energy onto a selected location on the surface of an object and receives energy from the location and generates electrical pulses. The phase of the high frequency electrical signal pulses are stepped with respect to the phase of a reference signal at said location. An output signal is generated which is indicative of the surface of said selected location. The object is scanned to provide output signals representative of the surface at a plurality of surface locations. 7 figures.
Characterizing the cavitation development and acoustic spectrum in various liquids.
Tzanakis, I; Lebon, G S B; Eskin, D G; Pericleous, K A
2017-01-01
A bespoke cavitometer that measures acoustic spectrum and is capable of operating in a range of temperatures (up to 750°C) was used to study the cavitation behaviour in three transparent liquids and in molten aluminium. To relate these acoustic measurements to cavitation development, the dynamics of the cavitation bubble structures was observed in three Newtonian, optically transparent liquids with significantly different physical properties: water, ethanol, and glycerine. Each liquid was treated at 20kHz with a piezoelectric ultrasonic transducer coupled to a titanium sonotrode with a tip diameter of 40mm. Two different transducer power levels were deployed: 50% and 100%, with the maximum power corresponding to a peak-to-peak amplitude of 17μm. The cavitation structures and the flow patterns were filmed with a digital camera. To investigate the effect of distance from the ultrasound source on the cavitation intensity, acoustic emissions were measured with the cavitometer at two points: below the sonotrode and near the edge of the experimental vessel. The behaviour of the three tested liquids was very different, implying that their physical parameters played a decisive role in the establishment of the cavitation regime. Non dimensional analysis revealed that water shares the closest cavitation behaviour with liquid aluminium and can therefore be used as its physical analogue in cavitation studies; this similarity was also confirmed when comparing the measured acoustic spectra of water and liquid aluminium. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.
Arifler, Dogu; Arifler, Dizem
2017-04-01
For biomedical applications of nanonetworks, employing molecular communication for information transport is advantageous over nano-electromagnetic communication: molecular communication is potentially biocompatible and inherently energy-efficient. Recently, several studies have modeled receivers in diffusion-based molecular communication systems as "perfectly monitoring" or "perfectly absorbing" spheres based on idealized descriptions of chemoreception. In this paper, we focus on perfectly absorbing receivers and present methods to improve the accuracy of simulation procedures that are used to analyze these receivers. We employ schemes available from the chemical physics and biophysics literature and outline a Monte Carlo simulation algorithm that accounts for the possibility of molecule absorption during discrete time steps, leading to a more accurate analysis of absorption probabilities. Unlike most existing studies that consider a single receiver, this paper analyzes absorption probabilities for multiple receivers deterministically or randomly deployed in a region. For random deployments, the ultimate absorption probabilities as a function of transmitter-receiver distance are shown to fit well to power laws; the exponents derived become more negative as the number of receivers increases up to a limit beyond which no additional receivers can be "packed" in the deployment region. This paper is expected to impact the design of molecular nanonetworks with multiple absorbing receivers.
Passive acoustic monitoring to detect spawning in large-bodied catostomids
Straight, Carrie A.; Freeman, Byron J.; Freeman, Mary C.
2014-01-01
Documenting timing, locations, and intensity of spawning can provide valuable information for conservation and management of imperiled fishes. However, deep, turbid or turbulent water, or occurrence of spawning at night, can severely limit direct observations. We have developed and tested the use of passive acoustics to detect distinctive acoustic signatures associated with spawning events of two large-bodied catostomid species (River Redhorse Moxostoma carinatum and Robust Redhorse Moxostoma robustum) in river systems in north Georgia. We deployed a hydrophone with a recording unit at four different locations on four different dates when we could both record and observe spawning activity. Recordings captured 494 spawning events that we acoustically characterized using dominant frequency, 95% frequency, relative power, and duration. We similarly characterized 46 randomly selected ambient river noises. Dominant frequency did not differ between redhorse species and ranged from 172.3 to 14,987.1 Hz. Duration of spawning events ranged from 0.65 to 11.07 s, River Redhorse having longer durations than Robust Redhorse. Observed spawning events had significantly higher dominant and 95% frequencies than ambient river noises. We additionally tested software designed to automate acoustic detection. The automated detection configurations correctly identified 80–82% of known spawning events, and falsely indentified spawns 6–7% of the time when none occurred. These rates were combined over all recordings; rates were more variable among individual recordings. Longer spawning events were more likely to be detected. Combined with sufficient visual observations to ascertain species identities and to estimate detection error rates, passive acoustic recording provides a useful tool to study spawning frequency of large-bodied fishes that displace gravel during egg deposition, including several species of imperiled catostomids.
Array Receivers and Sound Sources for Three Dimensional Shallow Water Acoustic Field Experiments
2016-12-06
upgrade included improving the SHRU clocks by utilizing chip- scale atomic clocks (CSAC), enlarging battery packs to extend the operation duration, and...instrument upgrade included improving the SHRU clocks by utilizing chip-scale atomic clocks (CSAC), enlarging battery packs to extend the operation...Changing the deployment configuration to use dual pressure housings to augment the alkaline primary battery payload to achieve the one-year duration
Phased Array Focusing for Acoustic Wireless Power Transfer.
Tseng, Victor Farm-Guoo; Bedair, Sarah S; Lazarus, Nathan
2018-01-01
Wireless power transfer (WPT) through acoustic waves can achieve higher efficiencies than inductive coupling when the distance is above several times the transducer size. This paper demonstrates the use of ultrasonic phased arrays to focus power to receivers at arbitrary locations to increase the power transfer efficiency. Using a phased array consisting of 37 elements at a distance nearly 5 times the receiver transducer diameter, a factor of 2.6 increase in efficiency was achieved when compared to a case equivalent to a single large transducer with the same peak efficiency distance. The array has a total diameter of 7 cm, and transmits through air at 40 kHz to a 1.1-cm diameter receiver, achieving a peak overall efficiency of 4% at a distance of 5 cm. By adjusting the focal distance, the efficiency can also be maintained relatively constant at distances up to 9 cm. Numerical models were developed and shown to closely match the experimental energy transfer behavior; modeling results indicate that the efficiency can be further doubled by increasing the number of elements. For comparison, an inductive WPT system was also built with the diameters of the transmitting and receiving coils equivalent to the dimensions of the transmitting ultrasonic phased array and receiver transducer, and the acoustic WPT system achieved higher efficiencies than the inductive WPT system when the transmit-to-receive distance is above 5 cm. In addition, beam angle steering was demonstrated by using a simplified seven-element 1-D array, achieving power transfer less dependent on receiver placement.
2013-09-30
underwater acoustic communication technologies for autonomous distributed underwater networks, through innovative signal processing, coding, and navigation...in real enviroments , an offshore testbed has been developed to conduct field experimetns. The testbed consists of four nodes and has been deployed...Leadership by the Connecticut Technology Council. Dr. Zhaohui Wang joined the faculty of the Department of Electrical and Computer Engineering at
NASA Astrophysics Data System (ADS)
Krynkin, A.; Dolcetti, G.; Hunting, S.
2017-02-01
Accurate reconstruction of the surface roughness is of high importance to various areas of science and engineering. One important application of this technology is for remote monitoring of open channel flows through observing its dynamic surface roughness. In this paper a novel airborne acoustic method of roughness reconstruction is proposed and tested with a static rigid rough surface. This method is based on the acoustic holography principle and Kirchhoff approximation which make use of acoustic pressure data collected at multiple receiver points spread along an arch. The Tikhonov regularisation and generalised cross validation technique are used to solve the underdetermined system of equations for the acoustic pressures. The experimental data are collected above a roughness created with a 3D printer. For the given surface, it is shown that the proposed method works well with the various number of receiver positions. In this paper, the tested ratios between the number of surface points at which the surface elevation can be reconstructed and number of receiver positions are 2.5, 5, and 7.5. It is shown that, in a region comparable with the projected size of the main directivity lobe, the method is able to reconstruct the spatial spectrum density of the actual surface elevation with the accuracy of 20%.
Krynkin, A; Dolcetti, G; Hunting, S
2017-02-01
Accurate reconstruction of the surface roughness is of high importance to various areas of science and engineering. One important application of this technology is for remote monitoring of open channel flows through observing its dynamic surface roughness. In this paper a novel airborne acoustic method of roughness reconstruction is proposed and tested with a static rigid rough surface. This method is based on the acoustic holography principle and Kirchhoff approximation which make use of acoustic pressure data collected at multiple receiver points spread along an arch. The Tikhonov regularisation and generalised cross validation technique are used to solve the underdetermined system of equations for the acoustic pressures. The experimental data are collected above a roughness created with a 3D printer. For the given surface, it is shown that the proposed method works well with the various number of receiver positions. In this paper, the tested ratios between the number of surface points at which the surface elevation can be reconstructed and number of receiver positions are 2.5, 5, and 7.5. It is shown that, in a region comparable with the projected size of the main directivity lobe, the method is able to reconstruct the spatial spectrum density of the actual surface elevation with the accuracy of 20%.
Carrier frequency offset estimation for an acoustic-electric channel using 16 QAM modulation
NASA Astrophysics Data System (ADS)
Cunningham, Michael T.; Anderson, Leonard A.; Wilt, Kyle R.; Chakraborty, Soumya; Saulnier, Gary J.; Scarton, Henry A.
2016-05-01
Acoustic-electric channels can be used to send data through metallic barriers, enabling communications where electromagnetic signals are ineffective. This paper considers an acoustic-electric channel that is formed by mounting piezoelectric transducers on metallic barriers that are separated by a thin water layer. The transducers are coupled to the barriers using epoxy and the barriers are positioned to axially-align the PZTs, maximizing energy transfer efficiency. The electrical signals are converted by the transmitting transducers into acoustic waves, which propagate through the elastic walls and water medium to the receiving transducers. The reverberation of the acoustic signals in these channels can produce multipath distortion with a significant delay spread that introduces inter-symbol interference (ISI) into the received signal. While the multipath effects can be severe, the channel does not change rapidly which makes equalization easier. Here we implement a 16-QAM system on this channel, including a method for obtaining accurate carrier frequency offset (CFO) estimates in the presence of the quasi-static multipath propagation. A raised-power approach is considered but found to suffer from excessive data noise resulting from the ISI. An alternative approach that utilizes a pilot tone burst at the start of a data packet is used for CFO estimation and found to be effective. The autocorrelation method is used to estimate the frequency of the received burst. A real-time prototype of the 16 QAM system that uses a Texas Instruments MSP430 microcontroller-based transmitter and a personal computer-based receiver is presented along with performance results.
Accurate positioning based on acoustic and optical sensors
NASA Astrophysics Data System (ADS)
Cai, Kerong; Deng, Jiahao; Guo, Hualing
2009-11-01
Unattended laser target designator (ULTD) was designed to partly take the place of conventional LTDs for accurate positioning and laser marking. Analyzed the precision, accuracy and errors of acoustic sensor array, the requirements of laser generator, and the technology of image analysis and tracking, the major system modules were determined. The target's classification, velocity and position can be measured by sensors, and then coded laser beam will be emitted intelligently to mark the excellent position at the excellent time. The conclusion shows that, ULTD can not only avoid security threats, be deployed massively, and accomplish battle damage assessment (BDA), but also be fit for information-based warfare.
Gewirtz, Abigail H.; McMorris, Barbara J.; Hanson, Sheila; Davis, Laurel
2014-01-01
Almost nothing is known about the family and individual adjustment of military mothers who have deployed to the conflicts in Iraq or Afghanistan (Operations Iraqi and Enduring Freedom, and Operation New Dawn; OIF, OEF, OND), constituting a gap in psychologists’ knowledge about how best to help this population. We report baseline data on maternal, child, parenting, and couple adjustment for mothers in 181 families in which a parent deployed to OIF/OEF/OND. Among this sample, 34 mothers had deployed at least once, and 147 mothers had experienced the deployment of a male spouse/partner. Mothers completed self-report questionnaires assessing past year adverse life events, war experiences (for deployed mothers only), posttraumatic stress disorder (PTSD) and depression symptoms, difficulties in emotion regulation, parenting, couple adjustment, and child functioning. Mothers who had deployed reported greater distress than non-deployed mothers (higher scores on measures of PTSD and depression symptoms), and slightly more past year adverse events. A moderate number of war experiences (combat and post-battle aftermath events) were reported, consistent with previous studies of women in current and prior conflicts. However, no differences were found between the two groups on measures of couple adjustment, parenting, or child functioning. Results are discussed in terms of the dearth of knowledge about deployed mothers, and implications for psychologists serving military families. PMID:25663739
Self-Deployable Membrane Structures
NASA Technical Reports Server (NTRS)
Sokolowski, Witold M.; Willis, Paul B.; Tan, Seng C.
2010-01-01
Currently existing approaches for deployment of large, ultra-lightweight gossamer structures in space rely typically upon electromechanical mechanisms and mechanically expandable or inflatable booms for deployment and to maintain them in a fully deployed, operational configuration. These support structures, with the associated deployment mechanisms, launch restraints, inflation systems, and controls, can comprise more than 90 percent of the total mass budget. In addition, they significantly increase the stowage volume, cost, and complexity. A CHEM (cold hibernated elastic memory) membrane structure without any deployable mechanism and support booms/structure is deployed by using shape memory and elastic recovery. The use of CHEM micro-foams reinforced with carbon nanotubes is considered for thin-membrane structure applications. In this advanced structural concept, the CHEM membrane structure is warmed up to allow packaging and stowing prior to launch, and then cooled to induce hibernation of the internal restoring forces. In space, the membrane remembers its original shape and size when warmed up. After the internal restoring forces deploy the structure, it is then cooled to achieve rigidization. For this type of structure, the solar radiation could be utilized as the heat energy used for deployment and space ambient temperature for rigidization. The overall simplicity of the CHEM self-deployable membrane is one of its greatest assets. In present approaches to space-deployable structures, the stow age and deployment are difficult and challenging, and introduce a significant risk, heavy mass, and high cost. Simple procedures provided by CHEM membrane greatly simplify the overall end-to-end process for designing, fabricating, deploying, and rigidizing large structures. The CHEM membrane avoids the complexities associated with other methods for deploying and rigidizing structures by eliminating deployable booms, deployment mechanisms, and inflation and control systems
Analytic Formulation and Numerical Implementation of an Acoustic Pressure Gradient Prediction
NASA Technical Reports Server (NTRS)
Lee, Seongkyu; Brentner, Kenneth S.; Farassat, Fereidoun
2007-01-01
The scattering of rotor noise is an area that has received little attention over the years, yet the limited work that has been done has shown that both the directivity and intensity of the acoustic field may be significantly modified by the presence of scattering bodies. One of the inputs needed to compute the scattered acoustic field is the acoustic pressure gradient on a scattering surface. Two new analytical formulations of the acoustic pressure gradient have been developed and implemented in the PSU-WOPWOP rotor noise prediction code. These formulations are presented in this paper. The first formulation is derived by taking the gradient of Farassat's retarded-time Formulation 1A. Although this formulation is relatively simple, it requires numerical time differentiation of the acoustic integrals. In the second formulation, the time differentiation is taken inside the integrals analytically. The acoustic pressure gradient predicted by these new formulations is validated through comparison with the acoustic pressure gradient determined by a purely numerical approach for two model rotors. The agreement between analytic formulations and numerical method is excellent for both stationary and moving observers case.
Effects of Various Architectural Parameters on Six Room Acoustical Measures in Auditoria.
NASA Astrophysics Data System (ADS)
Chiang, Wei-Hwa
The effects of architectural parameters on six room acoustical measures were investigated by means of correlation analyses, factor analyses and multiple regression analyses based on data taken in twenty halls. Architectural parameters were used to estimate acoustical measures taken at individual locations within each room as well as the averages and standard deviations of all measured values in the rooms. The six acoustical measures were Early Decay Time (EDT10), Clarity Index (C80), Overall Level (G), Bass Ratio based on Early Decay Time (BR(EDT)), Treble Ratio based on Early Decay Time (TR(EDT)), and Early Inter-aural Cross Correlation (IACC80). A comprehensive method of quantifying various architectural characteristics of rooms was developed to define a large number of architectural parameters that were hypothesized to effect the acoustical measurements made in the rooms. This study quantitatively confirmed many of the principles used in the design of concert halls and auditoria. Three groups of room architectural parameters such as the parameters associated with the depth of diffusing surfaces were significantly correlated with the hall standard deviations of most of the acoustical measures. Significant differences of statistical relations among architectural parameters and receiver specific acoustical measures were found between a group of music halls and a group of lecture halls. For example, architectural parameters such as the relative distance from the receiver to the overhead ceiling increased the percentage of the variance of acoustical measures that was explained by Barron's revised theory from approximately 70% to 80% only when data were taken in the group of music halls. This study revealed the major architectural parameters which have strong relations with individual acoustical measures forming the basis for a more quantitative method for advancing the theoretical design of concert halls and other auditoria. The results of this study provide
3D acoustic atmospheric tomography
NASA Astrophysics Data System (ADS)
Rogers, Kevin; Finn, Anthony
2014-10-01
This paper presents a method for tomographically reconstructing spatially varying 3D atmospheric temperature profiles and wind velocity fields based. Measurements of the acoustic signature measured onboard a small Unmanned Aerial Vehicle (UAV) are compared to ground-based observations of the same signals. The frequency-shifted signal variations are then used to estimate the acoustic propagation delay between the UAV and the ground microphones, which are also affected by atmospheric temperature and wind speed vectors along each sound ray path. The wind and temperature profiles are modelled as the weighted sum of Radial Basis Functions (RBFs), which also allow local meteorological measurements made at the UAV and ground receivers to supplement any acoustic observations. Tomography is used to provide a full 3D reconstruction/visualisation of the observed atmosphere. The technique offers observational mobility under direct user control and the capacity to monitor hazardous atmospheric environments, otherwise not justifiable on the basis of cost or risk. This paper summarises the tomographic technique and reports on the results of simulations and initial field trials. The technique has practical applications for atmospheric research, sound propagation studies, boundary layer meteorology, air pollution measurements, analysis of wind shear, and wind farm surveys.
Multi reflection of Lamb wave emission in an acoustic waveguide sensor.
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.
Multi Reflection of Lamb Wave Emission in an Acoustic Waveguide Sensor
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
Imaging and detection of mines from acoustic measurements
NASA Astrophysics Data System (ADS)
Witten, Alan J.; DiMarzio, Charles A.; Li, Wen; McKnight, Stephen W.
1999-08-01
A laboratory-scale acoustic experiment is described where a buried target, a hockey puck cut in half, is shallowly buried in a sand box. To avoid the need for source and receiver coupling to the host sand, an acoustic wave is generated in the subsurface by a pulsed laser suspended above the air-sand interface. Similarly, an airborne microphone is suspended above this interface and moved in unison with the laser. After some pre-processing of the data, reflections for the target, although weak, could clearly be identified. While the existence and location of the target can be determined by inspection of the data, its unique shape can not. Since target discrimination is important in mine detection, a 3D imaging algorithm was applied to the acquired acoustic data. This algorithm yielded a reconstructed image where the shape of the target was resolved.
NASA Astrophysics Data System (ADS)
Solé, Marta; Sigray, Peter; Lenoir, Marc; van der Schaar, Mike; Lalander, Emilia; André, Michel
2017-04-01
Recent findings on cephalopods in laboratory conditions showed that exposure to artificial noise had a direct consequence on the statocyst, sensory organs, which are responsible for their equilibrium and movements in the water column. The question remained about the contribution of the consequent near-field particle motion influence from the tank walls, to the triggering of the trauma. Offshore noise controlled exposure experiments (CEE) on common cuttlefish (Sepia officinalis), were conducted at three different depths and distances from the source and particle motion and sound pressure measurements were performed at each location. Scanning electron microscopy (SEM) revealed injuries in statocysts, which severity was quantified and found to be proportional to the distance to the transducer. These findings are the first evidence of cephalopods sensitivity to anthropogenic noise sources in their natural habitat. From the measured received power spectrum of the sweep, it was possible to determine that the animals were exposed at levels ranging from 139 to 142 dB re 1 μPa2 and from 139 to 141 dB re 1 μPa2, at 1/3 octave bands centred at 315 Hz and 400 Hz, respectively. These results could therefore be considered a coherent threshold estimation of noise levels that can trigger acoustic trauma in cephalopods.
NASA Astrophysics Data System (ADS)
Girard, L.; Beutel, J.; Gruber, S.; Hunziker, J.; Lim, R.; Weber, S.
2012-06-01
We present a custom acoustic emission (AE) monitoring system designed to perform long-term measurements on high-alpine rock-walls. AE monitoring is a common technique for characterizing damage evolution in solid materials. The system is based on a two-channel AE sensor node (AE-node) integrated into a Wireless Sensor Network (WSN) customized for operation in harsh environments. This wireless architecture offers flexibility in the deployment of AE-nodes at any position of the rock-wall that needs to be monitored, within a range of a few hundred meters from a core station connected to the internet. The system achieves near real-time data delivery and allows the user to remotely control the AE detection threshold. In order to protect AE sensors and capture acoustic signals from specific depths of the rock-wall, a special casing was developed. The monitoring system is completed by two probes that measure rock temperature and liquid water content, both probes being also integrated into the WSN. We report a first deployment of the monitoring system on a rock-wall at Jungfraujoch, 3500 m a.s.l., Switzerland. While this first deployment of the monitoring system aims to support fundamental research on processes that damage rock under cold climate, the system could serve a number of other applications, including rock-fall hazard surveillance or structural monitoring of concrete structures.
NASA Astrophysics Data System (ADS)
Girard, L.; Beutel, J.; Gruber, S.; Hunziker, J.; Lim, R.; Weber, S.
2012-11-01
We present a custom acoustic emission (AE) monitoring system designed to perform long-term measurements on high-alpine rock walls. AE monitoring is a common technique for characterizing damage evolution in solid materials. The system is based on a two-channel AE sensor node (AE-node) integrated into a wireless sensor network (WSN) customized for operation in harsh environments. This wireless architecture offers flexibility in the deployment of AE-nodes at any position of the rock wall that needs to be monitored, within a range of a few hundred meters from a core station connected to the internet. The system achieves near real-time data delivery and allows the user to remotely control the AE detection threshold. In order to protect AE sensors and capture acoustic signals from specific depths of the rock wall, a special casing was developed. The monitoring system is completed by two probes that measure rock temperature and liquid water content, both probes being also integrated into the WSN. We report a first deployment of the monitoring system on a rock wall at Jungfraujoch, 3500 m a.s.l., Switzerland. While this first deployment of the monitoring system aims to support fundamental research on processes that damage rock under cold climate, the system could serve a number of other applications, including rock fall hazard surveillance or structural monitoring of concrete structures.
Acoustic emission based damage localization in composites structures using Bayesian identification
NASA Astrophysics Data System (ADS)
Kundu, A.; Eaton, M. J.; Al-Jumali, S.; Sikdar, S.; Pullin, R.
2017-05-01
Acoustic emission based damage detection in composite structures is based on detection of ultra high frequency packets of acoustic waves emitted from damage sources (such as fibre breakage, fatigue fracture, amongst others) with a network of distributed sensors. This non-destructive monitoring scheme requires solving an inverse problem where the measured signals are linked back to the location of the source. This in turn enables rapid deployment of mitigative measures. The presence of significant amount of uncertainty associated with the operating conditions and measurements makes the problem of damage identification quite challenging. The uncertainties stem from the fact that the measured signals are affected by the irregular geometries, manufacturing imprecision, imperfect boundary conditions, existing damages/structural degradation, amongst others. This work aims to tackle these uncertainties within a framework of automated probabilistic damage detection. The method trains a probabilistic model of the parametrized input and output model of the acoustic emission system with experimental data to give probabilistic descriptors of damage locations. A response surface modelling the acoustic emission as a function of parametrized damage signals collected from sensors would be calibrated with a training dataset using Bayesian inference. This is used to deduce damage locations in the online monitoring phase. During online monitoring, the spatially correlated time data is utilized in conjunction with the calibrated acoustic emissions model to infer the probabilistic description of the acoustic emission source within a hierarchical Bayesian inference framework. The methodology is tested on a composite structure consisting of carbon fibre panel with stiffeners and damage source behaviour has been experimentally simulated using standard H-N sources. The methodology presented in this study would be applicable in the current form to structural damage detection under varying
Deployment simulation of a deployable reflector for earth science application
NASA Astrophysics Data System (ADS)
Wang, Xiaokai; Fang, Houfei; Cai, Bei; Ma, Xiaofei
2015-10-01
A novel mission concept namely NEXRAD-In-Space (NIS) has been developed for monitoring hurricanes, cyclones and other severe storms from a geostationary orbit. It requires a space deployable 35-meter diameter Ka-band (35 GHz) reflector. NIS can measure hurricane precipitation intensity, dynamics and its life cycle. These information is necessary for predicting the track, intensity, rain rate and hurricane-induced floods. To meet the requirements of the radar system, a Membrane Shell Reflector Segment (MSRS) reflector technology has been developed and several technologies have been evaluated. However, the deployment analysis of this large size and high-precision reflector has not been investigated. For a pre-studies, a scaled tetrahedral truss reflector with spring driving deployment system has been made and tested, deployment dynamics analysis of this scaled reflector has been performed using ADAMS to understand its deployment dynamic behaviors. Eliminating the redundant constraints in the reflector system with a large number of moving parts is a challenging issue. A primitive joint and flexible struts were introduced to the analytical model and they can effectively eliminate over constraints of the model. By using a high-speed camera and a force transducer, a deployment experiment of a single-bay tetrahedral module has been conducted. With the tested results, an optimization process has been performed by using the parameter optimization module of ADAMS to obtain the parameters of the analytical model. These parameters were incorporated to the analytical model of the whole reflector. It is observed from the analysis results that the deployment process of the reflector with a fixed boundary experiences three stages. These stages are rapid deployment stage, slow deployment stage and impact stage. The insight of the force peak distributions of the reflector can help the optimization design of the structure.
Ponce de León, Beatriz; Andersen, Søren; Karstoft, Karen-Inge; Elklit, Ask
2018-01-01
ABSTRACT Objective: This study investigated whether pre-deployment dissociation was associated with previously identified post-traumatic stress disorder (PTSD) symptom trajectories from before to 2.5 years after military deployment. Furthermore, it examined whether the tendency to dissociate, pre-deployment personality factors, conceptualized by the Big Five model, and previous trauma represented independent risk factors for post-deployment PTSD symptoms. Method: This prospective study included the entire team of 743 soldiers from the Danish Contingent of the International Security Assistance Force 7 deployed to Afghanistan in 2009. Data consisted of self-report measures and were collected six times: before deployment; during deployment; and 1–3 weeks, 2 months, 7 months and 2.5 years after homecoming. Results: The findings indicate significant associations between pre-deployment dissociation and six PTSD trajectories (p < 0.001, η2 = 0.120). Based on mean differences in dissociation for the six trajectories, two main groups emerged: a group with high dissociation scores at pre-deployment, which had moderate PTSD symptom levels at pre-deployment and fluctuated over time; and a group with low dissociation scores at pre-deployment, which had low initial PTSD symptom levels and diverged over time. Our study also confirmed previous findings of a positive association between neuroticism and dissociation (r = 0.31, p < 0.001). This suggests that negative emotionality may be a vulnerability that enhances dissociative experiences, although a causal link cannot be concluded from the findings. Finally, pre-deployment dissociation, pre-deployment neuroticism and a history of traumatic events, as independent factors, were significant predictors of post-deployment PTSD (p < 0.001, R2 = 0.158). Conclusions: The study emphasizes the multiplicity of factors involved in the development of PTSD, and group differences in dissociative symptoms support the
NASA Astrophysics Data System (ADS)
Anderson, J.; Johnson, J. B.; Arechiga, R. O.; Edens, H. E.; Thomas, R. J.
2011-12-01
We use radio frequency (VHF) pulse locations mapped with the New Mexico Tech Lightning Mapping Array (LMA) to study the distribution of thunder sources in lightning channels. A least squares inversion is used to fit channel acoustic energy radiation with broadband (0.01 to 500 Hz) acoustic recordings using microphones deployed local (< 10 km) to the lightning. We model the thunder (acoustic) source as a superposition of line segments connecting the LMA VHF pulses. An optimum branching algorithm is used to reconstruct conductive channels delineated by VHF sources, which we discretize as a superposition of finely-spaced (0.25 m) acoustic point sources. We consider total radiated thunder as a weighted superposition of acoustic waves from individual channels, each with a constant current along its length that is presumed to be proportional to acoustic energy density radiated per unit length. Merged channels are considered as a linear sum of current-carrying branches and radiate proportionally greater acoustic energy. Synthetic energy time series for a given microphone location are calculated for each independent channel. We then use a non-negative least squares inversion to solve for channel energy densities to match the energy time series determined from broadband acoustic recordings across a 4-station microphone network. Events analyzed by this method have so far included 300-1000 VHF sources, and correlations as high as 0.5 between synthetic and recorded thunder energy were obtained, despite the presence of wind noise and 10-30 m uncertainty in VHF source locations.
Fundamentals of Acoustics. Psychoacoustics and Hearing. Acoustical Measurements
NASA Technical Reports Server (NTRS)
Begault, Durand R.; Ahumada, Al (Technical Monitor)
1997-01-01
These are 3 chapters that will appear in a book titled "Building Acoustical Design", edited by Charles Salter. They are designed to introduce the reader to fundamental concepts of acoustics, particularly as they relate to the built environment. "Fundamentals of Acoustics" reviews basic concepts of sound waveform frequency, pressure, and phase. "Psychoacoustics and Hearing" discusses the human interpretation sound pressure as loudness, particularly as a function of frequency. "Acoustic Measurements" gives a simple overview of the time and frequency weightings for sound pressure measurements that are used in acoustical work.
Modal processing for acoustic communications in shallow water experiment.
Morozov, Andrey K; Preisig, James C; Papp, Joseph
2008-09-01
Acoustical array data from the Shallow Water Acoustics experiment was processed to show the feasibility of broadband mode decomposition as a preprocessing method to reduce the effective channel delay spread and concentrate received signal energy in a small number of independent channels. The data were collected by a vertical array designed at the Woods Hole Oceanographic Institution. Phase-shift Keying (PSK) m-sequence modulated signals with different carrier frequencies were transmitted at a distance 19.2 km from the array. Even during a strong internal waves activity a low bit error rate was achieved.
Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO
NASA Technical Reports Server (NTRS)
Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.
2011-01-01
Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This paper employees the Multilevel Fast Multipole Method (MLFMM) feature of a commercial electromagnetic tool to model the fairing electromagnetic environment in the presence of an internal transmitter. This work is an extension of the perfect electric conductor model that was used to represent the bare aluminum internal fairing cavity. This fairing model includes typical acoustic blanketing commonly used in vehicle fairings. Representative material models within FEKO were successfully used to simulate the test case.
Environmental Fluctuations and Acoustic Data Communications
2015-09-30
July 2011 along with subsequent analysis of the experiment data. KAM11 Experiment (2011) A shallow water acoustic communications experiment...packet and packet-to-packet variability. Algorithm Design and Experiment Data Analysis Communication receiver algorithm design for shallow water is...exhibited substantial daily oceanographic variability. Analysis of the KAM11 experiment data this past year has focused on fixed source transmissions
Joint Acoustic Propagation Experiment (JAPE)
NASA Technical Reports Server (NTRS)
Carnes, Benny L.; Olsen, Robert O.; Kennedy, Bruce W.
1993-01-01
The Joint Acoustic Propagation Experiment (JAPE), performed under the auspices of NATO and the Acoustics Working Group, was conducted at White Sands Missile Range, New Mexico, USA, during the period 11-28 Jul. 1991. JAPE consisted of 220 trials using various acoustic sources including speakers, propane cannon, various types of military vehicles, helicopters, a 155mm howitzer, and static high explosives. Of primary importance to the performance of these tests was the intensive characterization of the atmosphere before and during the trials. Because of the wide range of interests on the part of the participants, JAPE was organized in such a manner to provide a broad cross section of test configurations. These included short and long range propagation from fixed and moving vehicles, terrain masking, and vehicle detection. A number of independent trials were also performed by individual participating agencies using the assets available during JAPE. These tests, while not documented in this report, provided substantial and important data to those groups. Perhaps the most significant feature of JAPE is the establishment of a permanent data base which can be used by not only the participants but by others interested in acoustics. A follow-on test was performed by NASA LaRC during the period 19-29 Aug. 1991 at the same location. These trials consisted of 59 overflights of supersonic aircraft in order to establish the relationship between atmospheric turbulence and the received sonic boom energy at the surface.
Acoustic source for generating an acoustic beam
Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian
2016-05-31
An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.
Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors
NASA Technical Reports Server (NTRS)
Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)
1995-01-01
An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.
Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors
NASA Technical Reports Server (NTRS)
Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)
1994-01-01
An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.
Dispersion and Input Control Capability in European Large Size Reverberant Acoustic Chambers
NASA Astrophysics Data System (ADS)
Yarza, A.; Lopez, J.; Ozores, E.
2012-07-01
The acoustic test in reverberant chamber is one of the load cases to be proved during the environmental test campaign that demonstrates the capability of a space- unit to survive the launch phase. The crucial requirement for the large size structures is often the survival of the acoustic vibration test, and can be defined as the design driver load case in many circumstances. In addition, the commercial market demands lighter structures as an objective to reduce costs. For an efficient optimisation of the product it is very important to have powerful structural analysis tools in order to obtain knowledge of the structural needs and to refine existing methods for the prediction of structural loads experienced during acoustic testing. In the same line, as part of the contributors involved in the test it is important to acquire knowledge of the characteristics of the reverberant chamber itself and the behaviour of the fluid. With this purpose, EADS CASA Espacio (ECE) has used the measured data of the parameters of the fluid extracted from test of the deployable reflectors validated in the past five years, with the final objective to improve and optimise the capability to face up the acoustic test. In this paper experimental data extracted from acoustic tests performed to space-units are presented. Information related to two European large size acoustic chambers are used. The pressure field inside the acoustic chamber has been post-processed with the objective to study the behaviour of the fluid during the test. The diffuseness of the pressure field and the control capability of the acoustic profile are parameters to be considered as contributors for the design of the structures. The homogeneity of the microphones’ measurements is taken into account to describe the dispersion of the pressure inside the reverberant chamber along the frequency domain. Upon of that, the capability of the facilities to control the input profile is analysed from a statistical point of view
North Pacific Acoustic Laboratory and Deep Water Acoustics
2015-09-30
range acoustic systems, whether for acoustic surveillance, communication, or remote sensing of the ocean interior . The data from the NPAL network, and...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. North Pacific Acoustic Laboratory and Deep Water... Acoustics PI James A. Mercer Applied Physics Laboratory, University of Washington 1013 NE 40th Street Seattle, WA 98105 phone: (206) 543-1361 fax
TRIMETHYLTIN DISRUPTS ACOUSTIC STARTLE RESPONDING IN ADULT RATS
Trimethyltin (TMT) is a limbic-system toxicant which also produces sensory dysfunction in adult animals. In the present experiment, the authors examined the effects of TMT on the acoustic startle response. Adult male, Long-Evans rats (N=12/dose) received a single i.p. injection o...
Transducer Design Experiments for Ground-Penetrating Acoustic Systems
1996-03-19
subsurface imaging experiments have utilized a source (Tx) and receiver (Rx) configuration in which signals produced by a transmitter at the soil surface...development in the field of acoustic subsurface imaging are as follows. First, a transmitter designed to minimize the emission of surface waves, while
Heenehan, Heather L; Tyne, Julian A; Bejder, Lars; Van Parijs, Sofie M; Johnston, David W
2016-07-01
Effective decision making to protect coastally associated dolphins relies on monitoring the presence of animals in areas that are critical to their survival. Hawaiian spinner dolphins forage at night and rest during the day in shallow bays. Due to their predictable presence, they are targeted by dolphin-tourism. In this study, comparisons of presence were made between passive acoustic monitoring (PAM) and vessel-based visual surveys in Hawaiian spinner dolphin resting bays. DSG-Ocean passive acoustic recording devices were deployed in four bays along the Kona Coast of Hawai'i Island between January 8, 2011 and August 30, 2012. The devices sampled at 80 kHz, making 30-s recordings every four minutes. Overall, dolphins were acoustically detected on 37.1% to 89.6% of recording days depending on the bay. Vessel-based visual surveys overlapped with the PAM surveys on 202 days across the four bays. No significant differences were found between visual and acoustic detections suggesting acoustic surveys can be used as a proxy for visual surveys. Given the need to monitor dolphin presence across sites, PAM is the most suitable and efficient tool for monitoring long-term presence/absence. Concomitant photo-identification surveys are necessary to address changes in abundance over time.
Evaluation of multiple-frequency, active and passive acoustics as surrogates for bedload transport
Wood, Molly S.; Fosness, Ryan L.; Pachman, Gregory; Lorang, Mark; Tonolla, Diego
2015-01-01
The use of multiple-frequency, active acoustics through deployment of acoustic Doppler current profilers (ADCPs) shows potential for estimating bedload in selected grain size categories. The U.S. Geological Survey (USGS), in cooperation with the University of Montana (UM), evaluated the use of multiple-frequency, active and passive acoustics as surrogates for bedload transport during a pilot study on the Kootenai River, Idaho, May 17-18, 2012. Four ADCPs with frequencies ranging from 600 to 2000 kHz were used to measure apparent moving bed velocities at 20 stations across the river in conjunction with physical bedload samples. Additionally, UM scientists measured the sound frequencies of moving particles with two hydrophones, considered passive acoustics, along longitudinal transects in the study reach. Some patterns emerged in the preliminary analysis which show promise for future studies. Statistically significant relations were successfully developed between apparent moving bed velocities measured by ADCPs with frequencies 1000 and 1200 kHz and bedload in 0.5 to 2.0 mm grain size categories. The 600 kHz ADCP seemed somewhat sensitive to the movement of gravel bedload in the size range 8.0 to 31.5 mm, but the relation was not statistically significant. The passive hydrophone surveys corroborated the sample results and could be used to map spatial variability in bedload transport and to select a measurement cross-section with moving bedload for active acoustic surveys and physical samples.
NASA Astrophysics Data System (ADS)
Iezzi, A. M.; Fee, D.; Matoza, R. S.; Jolly, A. D.; Kim, K.; Christenson, B. W.; Johnson, R.; Kilgour, G.; Garaebiti, E.; Austin, A.; Kennedy, B.; Fitzgerald, R.; Gomez, C.; Key, N.
2017-12-01
Well-constrained acoustic waveform inversion can provide robust estimates of erupted volume and mass flux, increasing our ability to monitor volcanic emissions (potentially in real-time). Previous studies have made assumptions about the multipole source mechanism, which can be represented as the combination of pressure fluctuations from a volume change, directionality, and turbulence. The vertical dipole has not been addressed due to ground-based recording limitations. In this study we deployed a high-density seismo-acoustic network around Yasur Volcano, Vanuatu, including multiple acoustic sensors along a tethered balloon that was moved every 15-60 minutes. Yasur has frequent strombolian eruptions every 1-4 minutes from any one of three active vents within a 400 m diameter crater. Our experiment captured several explosions from each vent at 38 tether locations covering 200 in azimuth and a take-off range of 50 (Jolly et. al., in review). Additionally, FLIR, FTIR, and a variety of visual imagery were collected during the deployment to aid in the seismo-acoustic interpretations. The third dimension (vertical) of pressure sensor coverage allows us to more completely constrain the acoustic source. Our analysis employs Finite-Difference Time-Domain (FDTD) modeling to obtain the full 3-D Green's functions for each propagation path. This method, following Kim et al. (2015), takes into account realistic topographic scattering based on a high-resolution digital elevation model created using structure-from-motion techniques. We then invert for the source location and multipole source-time function using a grid-search approach. We perform this inversion for multiple events from vents A and C to examine the source characteristics of the vents, including an infrasound-derived volume flux as a function of time. These volumes fluxes are then compared to those derived independently from geochemical and seismic inversion techniques. Jolly, A., Matoza, R., Fee, D., Kennedy, B
Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.
Xie, Yangbo; Wang, Wenqi; Chen, Huanyang; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A
2014-11-24
Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications.
Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing
NASA Technical Reports Server (NTRS)
Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.
2009-01-01
Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in
To Become Senders, Songbirds Must be Receivers First.
Rodríguez-Saltos, Carlos Antonio
2017-10-01
Courtship signals are attractive; in other words, receivers are motivated to approach courtship signals. Though the concept of a receiver is commonly associated in the literature with that of a mate seeker, young songbirds that are learning to sing by imitating conspecifics are also receivers. Juvenile songbirds are attracted to conspecific songs, which has been shown by juveniles working to hear song in operant chambers. The mechanisms explaining this attraction are poorly understood. Here, I review studies that hint at the mechanisms by which conspecific song becomes attractive. In at least some species, juveniles imitate individuals with which they have a strong social bond, such as the father. Such cases suggest that social reward plays a role in the process of song becoming attractive. In addition, experiments using birds reared in isolation from conspecific song have shown that juveniles imitate songs that have acoustic features that are typically found in conspecific song. Those studies suggest that such features are attractive to juveniles regardless of their social experience. The relative contributions of social reward and species-typical acoustic features to the attractiveness of a song can be determined using methods such as operant conditioning. For example, juvenile songbirds can be given control over the playback of songs that differ in a given attribute, such as acoustic similarity to the song of the father. The juveniles will frequently elicit playback of the songs that are attractive to them. Investigating the mechanisms that contribute to the attractiveness of conspecific song to learners will broaden our understanding of the evolution of song as a courtship signal, because the preferences of learners may ultimately determine what will be sung to potential mates. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.
Lightning Location Using Acoustic Signals
NASA Astrophysics Data System (ADS)
Badillo, E.; Arechiga, R. O.; Thomas, R. J.
2013-05-01
In the summer of 2011 and 2012 a network of acoustic arrays was deployed in the Magdalena mountains of central New Mexico to locate lightning flashes. A Times-Correlation (TC) ray-tracing-based-technique was developed in order to obtain the location of lightning flashes near the network. The TC technique, locates acoustic sources from lightning. It was developed to complement the lightning location of RF sources detected by the Lightning Mapping Array (LMA) developed at Langmuir Laboratory, in New Mexico Tech. The network consisted of four arrays with four microphones each. The microphones on each array were placed in a triangular configuration with one of the microphones in the center of the array. The distance between the central microphone and the rest of them was about 30 m. The distance between centers of the arrays ranged from 500 m to 1500 m. The TC technique uses times of arrival (TOA) of acoustic waves to trace back the location of thunder sources. In order to obtain the times of arrival, the signals were filtered in a frequency band of 2 to 20 hertz and cross-correlated. Once the times of arrival were obtained, the Levenberg-Marquardt algorithm was applied to locate the spatial coordinates (x,y, and z) of thunder sources. Two techniques were used and contrasted to compute the accuracy of the TC method: Nearest-Neighbors (NN), between acoustic and LMA located sources, and standard deviation from the curvature matrix of the system as a measure of dispersion of the results. For the best case scenario, a triggered lightning event, the TC method applied with four microphones, located sources with a median error of 152 m and 142.9 m using nearest-neighbors and standard deviation respectively.; Results of the TC method in the lightning event recorded at 18:47:35 UTC, August 6, 2012. Black dots represent the results computed. Light color dots represent the LMA data for the same event. The results were obtained with the MGTM station (four channels). This figure
Shelf-Scale Mapping of Fish Distribution Using Active and Passive Acoustics
NASA Astrophysics Data System (ADS)
Wall, Carrie C.
managers in determining critical spawning times and areas. Over 403,000 acoustic recordings were made across an approximately 39,000 km2 area on the WFS during periods throughout 2008 to 2011 using stationary passive acoustic recorders and hydrophone-integrated gliders. A custom MySQL database with a portal to MATLAB was developed to catalogue and process the large acoustic dataset stored on a server. Analyses of these data determined the daily, seasonal and spatial patterns of red grouper as well as toadfish and several unconfirmed fish species termed: 100 Hz Pulsing, 6 kHz Sound, 300 Hz FM Harmonic, and 365 Hz Harmonic. Red grouper sound production was correlated to sunrise and sunset, and was primarily recorded in water 15 to 93 m deep, with increased calling within known hard bottom areas and in Steamboat Lumps Marine Reserve. Analyses of high-resolution multibeam bathymetry collected in a portion of the reserve in 2006 and 2009 allowed detailed documentation and characterization of holes excavated by red grouper. Comparisons of the spatially overlapping datasets suggested holes are constructed and maintained over time, and provided evidence towards an increase in spawning habitat usage. High rates of sound production recorded from stationary recorders and a glider deployment were correlated to high hole density in Steamboat Lumps. This research demonstrates the utility of coupling passive acoustic data with high-resolution bathymetric data to verify the occupation of suspected male territory (holes) and to provide a more complete understanding of effective spawning habitat. Annual peaks in calling (July and August, and November and December) did not correspond to spawning peaks (March -- May); however, passive acoustic monitoring was established as an effective tool to identify areas of potential spawning activity by recording the presence of red grouper. Sounds produced by other species of fish were recorded in the passive acoustic dataset. The distribution of
Extreme Low Frequency Acoustic Measurement System
NASA Technical Reports Server (NTRS)
Shams, Qamar A. (Inventor); Zuckerwar, Allan J. (Inventor)
2017-01-01
The present invention is an extremely low frequency (ELF) microphone and acoustic measurement system capable of infrasound detection in a portable and easily deployable form factor. In one embodiment of the invention, an extremely low frequency electret microphone comprises a membrane, a backplate, and a backchamber. The backchamber is sealed to allow substantially no air exchange between the backchamber and outside the microphone. Compliance of the membrane may be less than ambient air compliance. The backplate may define a plurality of holes and a slot may be defined between an outer diameter of the backplate and an inner wall of the microphone. The locations and sizes of the holes, the size of the slot, and the volume of the backchamber may be selected such that membrane motion is substantially critically damped.
Extreme low frequency acoustic measurement system
NASA Technical Reports Server (NTRS)
Shams, Qamar A. (Inventor); Zuckerwar, Allan J. (Inventor)
2013-01-01
The present invention is an extremely low frequency (ELF) microphone and acoustic measurement system capable of infrasound detection in a portable and easily deployable form factor. In one embodiment of the invention, an extremely low frequency electret microphone comprises a membrane, a backplate, and a backchamber. The backchamber is sealed to allow substantially no air exchange between the backchamber and outside the microphone. Compliance of the membrane may be less than ambient air compliance. The backplate may define a plurality of holes and a slot may be defined between an outer diameter of the backplate and an inner wall of the microphone. The locations and sizes of the holes, the size of the slot, and the volume of the backchamber may be selected such that membrane motion is substantially critically damped.
NASA Astrophysics Data System (ADS)
Kim, Hansoo; Kang, Donhyug; Jung, Seung Won
2018-03-01
The overgrowth of phytoplankton leads to negative effects such as harmful algal blooms (HABs, also called red tides) in marine environments. The HAB species Cochlodinium polykrikoides ( C. polykrikoides) appears frequently in Korea during summer. In this study, we developed a real-time acoustic detection and remote-control system to detect red tides using an ultrasonic digital sensor. In the laboratory, the acoustic signals increased as the number of cells increased. At the same time, for field application, we deployed the system near the southern coast of Korea, where red tides frequently occurred in summer seasons 2013-2015. The system developed here detected red tides in situ, with a good correlation between the acoustic signals and C. polykrikoides populations. These results suggest that it may be useful for early detection of red tides.
NASA Astrophysics Data System (ADS)
Otsuka, Keisuke; Wang, Yinan; Makihara, Kanjuro
2017-11-01
In future, wings will be deployed in the span direction during flight. The deployment system improves flight ability and saves storage space in the airplane. For the safe design of the wing, the deployment motion needs to be simulated. In the simulation, the structural flexibility and aerodynamic unsteadiness should be considered because they may lead to undesirable phenomena such as a residual vibration after the deployment or a flutter during the deployment. In this study, the deployment motion is simulated in the time domain by using a nonlinear folding wing model based on multibody dynamics, absolute nodal coordinate formulation, and two-dimensional aerodynamics with strip theory. We investigate the effect of the structural flexibility and aerodynamic unsteadiness on the time-domain deployment simulation.
NASA Astrophysics Data System (ADS)
Bollard, Paul; Des Jardins, Stephen
2005-09-01
Prior to the construction of La Provence Restaurant in Roseville, California in 2004, the owner, Stephen Des Jardins, traveled with his cook, architect, and engineer to the Provence Region of France to study the cuisine, architecture, and acoustics of the local restaurants. This information was incorporated into the design, construction, and operation of his restaurant, with acoustical design assistance provided by the author, Paul Bollard. The result of the owner's painstaking attention to detail is a restaurant which has received very positive reviews for its architecture, quality of food, service, and acoustic ambience. This paper documents the measures included in the construction of the restaurant to ensure that the building acoustics enhance the dining experience, rather than detract from it. Photographs of acoustic treatments are included, as are reverberation time (RT60) test results and ambient noise level measurement results.
Preparedness Evaluation of French Military Orthopedic Surgeons Before Deployment.
Choufani, Camille; Barbier, Olivier; Mayet, Aurélie; Rigal, Sylvain; Mathieu, Laurent
2018-06-13
A deployed military orthopedic surgeon is a trauma surgeon working in austere conditions. The first aim of this study was to analyze the current activity of French military orthopedic surgeons in the field and to identify the differences of the combat zone with their daily practice. The second aim was to assess the adequacy of the preparedness they received before their deployment and to identify additional needs that could be addressed in future training. An evaluation survey was sent to all French military orthopedic surgeons deployed in theaters of operations between 2004 and 2014. An analogic visual scale of 10 was used to evaluate their surgical activity abroad and prior training. A total of 55 surgeons, with a median deployment number of 7, were included in this study after they answered the survey. Debridement and external fixation were the most common orthopedic procedures. The practice of general surgery was mostly concerned with vascular and abdominal injuries as part of damage control procedures. Median scores were ranked at seven for surgical preparedness, five for physical readiness, and three for mental preparedness. There was a significant inverse relationship between the number of missions performed and the evaluation of surgical preparedness. The higher they perceived their mental preparedness, the better they estimated their surgical preparedness. In the French Army, deployed orthopedic surgeons perform general surgical activity. Their initial training must be adapted to this constraint and enhanced by continuing medical education.
Abbot, Ted A; Premus, Vincent E; Abbot, Philip A; Mayer, Owen A
2012-09-01
This paper presents recent experimental results and a discussion of system enhancements made to the real-time autonomous humpback whale detector-classifier algorithm first presented by Abbot et al. [J. Acoust. Soc. Am. 127, 2894-2903 (2010)]. In February 2010, a second-generation system was deployed in an experiment conducted off of leeward Kauai during which 26 h of humpback vocalizations were recorded via sonobuoy and processed in real time. These data have been analyzed along with 40 h of humpbacks-absent data collected from the same location during July-August 2009. The extensive whales-absent data set in particular has enabled the quantification of system false alarm rates and the measurement of receiver operating characteristic curves. The performance impact of three enhancements incorporated into the second-generation system are discussed, including (1) a method to eliminate redundancy in the kernel library, (2) increased use of contextual analysis, and (3) the augmentation of the training data with more recent humpback vocalizations. It will be shown that the performance of the real-time system was improved to yield a probability of correct classification of 0.93 and a probability of false alarm of 0.004 over the 66 h of independent test data.
Van Uffelen, Lora J; Worcester, Peter F; Dzieciuch, Matthew A; Rudnick, Daniel L; Colosi, John A
2010-04-01
Deep acoustic shadow-zone arrivals observed in the late 1990s in the North Pacific Ocean reveal significant acoustic energy penetrating the geometric shadow. Comparisons of acoustic data obtained from vertical line arrays deployed in conjunction with 250-Hz acoustic sources at ranges of 500 and 1000 km from June to November 2004 in the North Pacific, with simulations incorporating scattering consistent with the Garrett-Munk internal-wave spectrum, are able to describe both the energy contained in and vertical extent of deep shadow-zone arrivals. Incoherent monthly averages of acoustic timefronts indicate that lower cusps associated with acoustic rays with shallow upper turning points (UTPs), where sound-speed structure is most variable and seasonally dependent, deepen from June to October as the summer thermocline develops. Surface-reflected rays, or those with near-surface UTPs, exhibit less scattering due to internal waves than in later months when the UTP deepens. Data collected in November exhibit dramatically more vertical extension than previous months. The depth to which timefronts extend is a complex combination of deterministic changes in the depths of the lower cusps as the range-average profiles evolve with seasonal change and of the amount of scattering, which depends on the mean vertical gradients at the depths of the UTPs.
Directional Reflective Surface Formed via Gradient-Impeding Acoustic Meta-Surfaces
Song, Kyungjun; Kim, Jedo; Hur, Shin; Kwak, Jun-Hyuk; Lee, Seong-Hyun; Kim, Taesung
2016-01-01
Artificially designed acoustic meta-surfaces have the ability to manipulate sound energy to an extraordinary extent. Here, we report on a new type of directional reflective surface consisting of an array of sub-wavelength Helmholtz resonators with varying internal coiled path lengths, which induce a reflection phase gradient along a planar acoustic meta-surface. The acoustically reshaped reflective surface created by the gradient-impeding meta-surface yields a distinct focal line similar to a parabolic cylinder antenna, and is used for directive sound beamforming. Focused beam steering can be also obtained by repositioning the source (or receiver) off axis, i.e., displaced from the focal line. Besides flat reflective surfaces, complex surfaces such as convex or conformal shapes may be used for sound beamforming, thus facilitating easy application in sound reinforcement systems. Therefore, directional reflective surfaces have promising applications in fields such as acoustic imaging, sonic weaponry, and underwater communication. PMID:27562634
NASA Astrophysics Data System (ADS)
Bishop, Steven S.; Moore, Timothy R.; Gugino, Peter; Smith, Brett; Kirkwood, Kathryn P.; Korman, Murray S.
2018-04-01
High Bandwidth Acoustic Detection System (HBADS) is an emerging active acoustic sensor technology undergoing study by the US Army's Night Vision and Electronic Sensors Directorate. Mounted on a commercial all-terrain type vehicle, it uses a single source pulse chirp while moving and a new array (two rows each containing eight microphones) mounted horizontally and oriented in a side scan mode. Experiments are performed with this synthetic aperture air acoustic (SAA) array to image canonical ground targets in clutter or foliage. A commercial audio speaker transmits a linear FM chirp having an effective frequency range of 2 kHz to 15 kHz. The system includes an inertial navigation system using two differential GPS antennas, an inertial measurement unit and a wheel coder. A web camera is mounted midway between the two horizontal microphone arrays and a meteorological unit acquires ambient, temperature, pressure and humidity information. A data acquisition system is central to the system's operation, which is controlled by a laptop computer. Recent experiments include imaging canonical targets located on the ground in a grassy field and similar targets camouflaged by natural vegetation along the side of a road. A recent modification involves implementing SAA stripmap mode interferometry for computing the reflectance of targets placed along the ground. Typical strip map SAA parameters are chirp pulse = 10 or 40 ms, slant range resolution c/(2*BW) = 0.013 m, microphone diameter D = 0.022 m, azimuthal resolution (D/2) = 0.01, air sound speed c ≍ 340 m/s and maximum vehicle speed ≍ 2 m/s.
Time Reversal Acoustic Communication Using Filtered Multitone Modulation
Sun, Lin; Chen, Baowei; Li, Haisen; Zhou, Tian; Li, Ruo
2015-01-01
The multipath spread in underwater acoustic channels is severe and, therefore, when the symbol rate of the time reversal (TR) acoustic communication using single-carrier (SC) modulation is high, the large intersymbol interference (ISI) span caused by multipath reduces the performance of the TR process and needs to be removed using the long adaptive equalizer as the post-processor. In this paper, a TR acoustic communication method using filtered multitone (FMT) modulation is proposed in order to reduce the residual ISI in the processed signal using TR. In the proposed method, FMT modulation is exploited to modulate information symbols onto separate subcarriers with high spectral containment and TR technique, as well as adaptive equalization is adopted at the receiver to suppress ISI and noise. The performance of the proposed method is assessed through simulation and real data from a trial in an experimental pool. The proposed method was compared with the TR acoustic communication using SC modulation with the same spectral efficiency. Results demonstrate that the proposed method can improve the performance of the TR process and reduce the computational complexity of adaptive equalization for post-process. PMID:26393586
Time Reversal Acoustic Communication Using Filtered Multitone Modulation.
Sun, Lin; Chen, Baowei; Li, Haisen; Zhou, Tian; Li, Ruo
2015-09-17
The multipath spread in underwater acoustic channels is severe and, therefore, when the symbol rate of the time reversal (TR) acoustic communication using single-carrier (SC) modulation is high, the large intersymbol interference (ISI) span caused by multipath reduces the performance of the TR process and needs to be removed using the long adaptive equalizer as the post-processor. In this paper, a TR acoustic communication method using filtered multitone (FMT) modulation is proposed in order to reduce the residual ISI in the processed signal using TR. In the proposed method, FMT modulation is exploited to modulate information symbols onto separate subcarriers with high spectral containment and TR technique, as well as adaptive equalization is adopted at the receiver to suppress ISI and noise. The performance of the proposed method is assessed through simulation and real data from a trial in an experimental pool. The proposed method was compared with the TR acoustic communication using SC modulation with the same spectral efficiency. Results demonstrate that the proposed method can improve the performance of the TR process and reduce the computational complexity of adaptive equalization for post-process.
Thin-film sparse boundary array design for passive acoustic mapping during ultrasound therapy.
Coviello, Christian M; Kozick, Richard J; Hurrell, Andrew; Smith, Penny Probert; Coussios, Constantin-C
2012-10-01
A new 2-D hydrophone array for ultrasound therapy monitoring is presented, along with a novel algorithm for passive acoustic mapping using a sparse weighted aperture. The array is constructed using existing polyvinylidene fluoride (PVDF) ultrasound sensor technology, and is utilized for its broadband characteristics and its high receive sensitivity. For most 2-D arrays, high-resolution imagery is desired, which requires a large aperture at the cost of a large number of elements. The proposed array's geometry is sparse, with elements only on the boundary of the rectangular aperture. The missing information from the interior is filled in using linear imaging techniques. After receiving acoustic emissions during ultrasound therapy, this algorithm applies an apodization to the sparse aperture to limit side lobes and then reconstructs acoustic activity with high spatiotemporal resolution. Experiments show verification of the theoretical point spread function, and cavitation maps in agar phantoms correspond closely to predicted areas, showing the validity of the array and methodology.
Petersen, T.
2007-01-01
In summer 2003, a Chaparral Model 2 microphone was deployed at Shishaldin Volcano, Aleutian Islands, Alaska. The pressure sensor was co-located with a short-period seismometer on the volcano’s north flank at a distance of 6.62 km from the active summit vent. The seismo-acoustic data exhibit a correlation between impulsive acoustic signals (1–2 Pa) and long-period (LP, 1–2 Hz) earthquakes. Since it last erupted in 1999, Shishaldin has been characterized by sustained seismicity consisting of many hundreds to two thousand LP events per day. The activity is accompanied by up to ∼200 m high discrete gas puffs exiting the small summit vent, but no significant eruptive activity has been confirmed. The acoustic waveforms possess similarity throughout the data set (July 2003–November 2004) indicating a repetitive source mechanism. The simplicity of the acoustic waveforms, the impulsive onsets with relatively short (∼10–20 s) gradually decaying codas and the waveform similarities suggest that the acoustic pulses are generated at the fluid–air interface within an open-vent system. SO2 measurements have revealed a low SO2 flux, suggesting a hydrothermal system with magmatic gases leaking through. This hypothesis is supported by the steady-state nature of Shishaldin’s volcanic system since 1999. Time delays between the seismic LP and infrasound onsets were acquired from a representative day of seismo-acoustic data. A simple model was used to estimate source depths. The short seismo-acoustic delay times have revealed that the seismic and acoustic sources are co-located at a depth of 240±200 m below the crater rim. This shallow depth is confirmed by resonance of the upper portion of the open conduit, which produces standing waves with f=0.3 Hz in the acoustic waveform codas. The infrasound data has allowed us to relate Shishaldin’s LP earthquakes to degassing explosions, created by gas volume ruptures from a fluid–air interface.
NW-MILO Acoustic Data Collection
DOE Office of Scientific and Technical Information (OSTI.GOV)
Matzner, Shari; Myers, Joshua R.; Maxwell, Adam R.
2010-02-17
There is an enduring requirement to improve our ability to detect potential threats and discriminate these from the legitimate commercial and recreational activity ongoing in the nearshore/littoral portion of the maritime domain. The Northwest Maritime Information and Littoral Operations (NW-MILO) Program at PNNL’s Coastal Security Institute in Sequim, Washington is establishing a methodology to detect and classify these threats - in part through developing a better understanding of acoustic signatures in a near-shore environment. The purpose of the acoustic data collection described here is to investigate the acoustic signatures of small vessels. The data is being recorded continuously, 24 hoursmore » a day, along with radar track data and imagery. The recording began in August 2008, and to date the data contains tens of thousands of signals from small vessels recorded in a variety of environmental conditions. The quantity and variety of this data collection, with the supporting imagery and radar track data, makes it particularly useful for the development of robust acoustic signature models and advanced algorithms for signal classification and information extraction. The underwater acoustic sensing system is part of a multi-modal sensing system that is operating near the mouth of Sequim Bay. Sequim Bay opens onto the Straight of Juan de Fuca, which contains part of the border between the U.S. and Canada. Table 1 lists the specific components used for the NW-MILO system. The acoustic sensor is a hydrophone permanently deployed at a mean depth of about 3 meters. In addition to a hydrophone, the other sensors in the system are a marine radar, an electro-optical (EO) camera and an infra-red (IR) camera. The radar is integrated with a vessel tracking system (VTS) that provides position, speed and heading information. The data from all the sensors is recorded and saved to a central server. The data has been validated in terms of its usability for characterizing the
Solé, Marta; Sigray, Peter; Lenoir, Marc; van der Schaar, Mike; Lalander, Emilia; André, Michel
2017-01-01
Recent findings on cephalopods in laboratory conditions showed that exposure to artificial noise had a direct consequence on the statocyst, sensory organs, which are responsible for their equilibrium and movements in the water column. The question remained about the contribution of the consequent near-field particle motion influence from the tank walls, to the triggering of the trauma. Offshore noise controlled exposure experiments (CEE) on common cuttlefish (Sepia officinalis), were conducted at three different depths and distances from the source and particle motion and sound pressure measurements were performed at each location. Scanning electron microscopy (SEM) revealed injuries in statocysts, which severity was quantified and found to be proportional to the distance to the transducer. These findings are the first evidence of cephalopods sensitivity to anthropogenic noise sources in their natural habitat. From the measured received power spectrum of the sweep, it was possible to determine that the animals were exposed at levels ranging from 139 to 142 dB re 1 μPa2 and from 139 to 141 dB re 1 μPa2, at 1/3 octave bands centred at 315 Hz and 400 Hz, respectively. These results could therefore be considered a coherent threshold estimation of noise levels that can trigger acoustic trauma in cephalopods. PMID:28378762
Large-region acoustic source mapping using a movable array and sparse covariance fitting.
Zhao, Shengkui; Tuna, Cagdas; Nguyen, Thi Ngoc Tho; Jones, Douglas L
2017-01-01
Large-region acoustic source mapping is important for city-scale noise monitoring. Approaches using a single-position measurement scheme to scan large regions using small arrays cannot provide clean acoustic source maps, while deploying large arrays spanning the entire region of interest is prohibitively expensive. A multiple-position measurement scheme is applied to scan large regions at multiple spatial positions using a movable array of small size. Based on the multiple-position measurement scheme, a sparse-constrained multiple-position vectorized covariance matrix fitting approach is presented. In the proposed approach, the overall sample covariance matrix of the incoherent virtual array is first estimated using the multiple-position array data and then vectorized using the Khatri-Rao (KR) product. A linear model is then constructed for fitting the vectorized covariance matrix and a sparse-constrained reconstruction algorithm is proposed for recovering source powers from the model. The user parameter settings are discussed. The proposed approach is tested on a 30 m × 40 m region and a 60 m × 40 m region using simulated and measured data. Much cleaner acoustic source maps and lower sound pressure level errors are obtained compared to the beamforming approaches and the previous sparse approach [Zhao, Tuna, Nguyen, and Jones, Proc. IEEE Intl. Conf. on Acoustics, Speech and Signal Processing (ICASSP) (2016)].
The Nature of Exhibits About Acoustics in Science and Technology Centres
NASA Astrophysics Data System (ADS)
Afonso, Ana S.; Gilbert, John K.
2008-11-01
This is a study of the opportunities currently provided by interactive science and technology centres for visitors’ engagement in the field of acoustics. E-mails, requesting a description of exhibits on acoustics (sound and hearing) in use, were sent to members of staff of interactive science and technology centres around the world as well as to companies that design and sell exhibits. Eighty-seven descriptions of distinctive interactive exhibits were received and analysed. Results show that: there are few analogy-based exhibits concerning the more complex aspects of acoustics; narratives involving visitors’ everyday lives, that might provide continuity between and beyond the situations presented by exhibits, are not generally provided; science is emphasised at the expense of technology; the risks, benefits and ethical implications of relevant technological artefacts are rarely mentioned; the majority of the exhibits are concerned with the fields of fundamental acoustics, hearing, and psychoacoustics. It is suggested that interactive science and technology centres need to rethink the design of exhibits about acoustics if their mission includes some appreciation of this important branch of science and technology.
Limousin, Denis; Streiff, Réjane; Courtois, Brigitte; Dupuy, Virginie; Alem, Sylvain; Greenfield, Michael D.
2012-01-01
Models of indirect (genetic) benefits sexual selection predict linkage disequilibria between genes that influence male traits and female preferences, owing to non-random mate choice or physical linkage. Such linkage disequilibria can accelerate the evolution of traits and preferences to exaggerated levels. Both theory and recent empirical findings on species recognition suggest that such linkage disequilibria may result from physical linkage or pleiotropy, but very little work has addressed this possibility within the context of sexual selection. We studied the genetic architecture of sexually selected traits by analyzing signals and preferences in an acoustic moth, Achroia grisella, in which males attract females with a train of ultrasound pulses and females prefer loud songs and a fast pulse rhythm. Both male signal characters and female preferences are repeatable and heritable traits. Moreover, female choice is based largely on male song, while males do not appear to provide direct benefits at mating. Thus, some genetic correlation between song and preference traits is expected. We employed a standard crossing design between inbred lines and used AFLP markers to build a linkage map for this species and locate quantitative trait loci (QTL) that influence male song and female preference. Our analyses mostly revealed QTLs of moderate strength that influence various male signal and female receiver traits, but one QTL was found that exerts a major influence on the pulse-pair rate of male song, a critical trait in female attraction. However, we found no evidence of specific co-localization of QTLs influencing male signal and female receiver traits on the same linkage groups. This finding suggests that the sexual selection process would proceed at a modest rate in A. grisella and that evolution toward exaggerated character states may be tempered. We suggest that this equilibrium state may be more the norm than the exception among animal species. PMID:22957082
Acoustic enhancement for photo detecting devices
Thundat, Thomas G; Senesac, Lawrence R; Van Neste, Charles W
2013-02-19
Provided are improvements to photo detecting devices and methods for enhancing the sensitivity of photo detecting devices. A photo detecting device generates an electronic signal in response to a received light pulse. An electro-mechanical acoustic resonator, electrically coupled to the photo detecting device, damps the electronic signal and increases the signal noise ratio (SNR) of the electronic signal. Increased photo detector standoff distances and sensitivities will result.
Acoustic Propagation Modeling in Shallow Water
1996-10-01
Oceanography La Jolla, California 92093-0701 (Received April 15, 1996) This paper provides references for the Navy’s existing databases . Various...a compilation of many aspects of high-frequency (OAML) contains a description of Navy models and acoustics. databases . The Navy’s use of shallow...become significant because the propagation path may involve many tens of bounces. A description of a reflectivity database is (b) Geometry for the
NASA Astrophysics Data System (ADS)
Cho, Young Y.; Chang, Cheng-Chung; Wang, Lihong V.; Zou, Jun
2015-03-01
To achieve real-time photoacoustic tomography (PAT), massive transducer arrays and data acquisition (DAQ) electronics are needed to receive the PA signals simultaneously, which results in complex and high-cost ultrasound receiver systems. To address this issue, we have developed a new PA data acquisition approach using acoustic time delay. Optical fibers were used as parallel acoustic delay lines (PADLs) to create different time delays in multiple channels of PA signals. This makes the PA signals reach a single-element transducer at different times. As a result, they can be properly received by single-channel DAQ electronics. However, due to their small diameter and fragility, using optical fiber as acoustic delay lines poses a number of challenges in the design, construction and packaging of the PADLs, thereby limiting their performances and use in real imaging applications. In this paper, we report the development of new silicon PADLs, which are directly made from silicon wafers using advanced micromachining technologies. The silicon PADLs have very low acoustic attenuation and distortion. A linear array of 16 silicon PADLs were assembled into a handheld package with one common input port and one common output port. To demonstrate its real-time PAT capability, the silicon PADL array (with its output port interfaced with a single-element transducer) was used to receive 16 channels of PA signals simultaneously from a tissue-mimicking optical phantom sample. The reconstructed PA image matches well with the imaging target. Therefore, the silicon PADL array can provide a 16× reduction in the ultrasound DAQ channels for real-time PAT.
Hanson, M Bradley; Emmons, Candice K; Ward, Eric J; Nystuen, Jeffrey A; Lammers, Marc O
2013-11-01
Using moored autonomous acoustic recorders to detect and record the vocalizations of social odonotocetes to determine their occurrence patterns is a non-invasive tool in the study of these species in remote locations. Acoustic recorders were deployed in seven locations on the continental shelf of the U.S. west coast from Cape Flattery, WA to Pt. Reyes, CA to detect and record endangered southern resident killer whales between January and June of 2006-2011. Detection rates of these whales were greater in 2009 and 2011 than in 2006-2008, were most common in the month of March, and occurred with the greatest frequency off the Columbia River and Westport, which was likely related to the presence of their most commonly consumed prey, Chinook salmon. The observed patterns of annual and monthly killer whale occurrence may be related to run strength and run timing, respectively, for spring Chinook returning to the Columbia River, the largest run in this region at this time of year. Acoustic recorders provided a unique, long-term, dataset that will be important to inform future consideration of Critical Habitat designation for this U.S. Endangered Species Act listed species.
Bai, Mingsian R; Wen, Jheng-Ciang; Hsu, Hoshen; Hua, Yi-Hsin; Hsieh, Yu-Hao
2014-10-01
A sound reconstruction system is proposed for audio reproduction with extended sweet spot and reduced reflections. An equivalent source method (ESM)-based sound field synthesis (SFS) approach, with the aid of dark zone minimization is adopted in the study. Conventional SFS that is based on the free-field assumption suffers from synthesis error due to boundary reflections. To tackle the problem, the proposed system utilizes convex optimization in designing array filters with both reproduction performance and acoustic contrast taken into consideration. Control points are deployed in the dark zone to minimize the reflections from the walls. Two approaches are employed to constrain the pressure and velocity in the dark zone. Pressure matching error (PME) and acoustic contrast (AC) are used as performance measures in simulations and experiments for a rectangular loudspeaker array. Perceptual Evaluation of Audio Quality (PEAQ) is also used to assess the audio reproduction quality. The results show that the pressure-constrained (PC) method yields better acoustic contrast, but poorer reproduction performance than the pressure-velocity constrained (PVC) method. A subjective listening test also indicates that the PVC method is the preferred method in a live room.
Martin, Stephen J.; Ricco, Antonio J.
1993-01-01
A chemical sensor (1) includes two or more pairs of interdigital electrodes (10) having different periodicities. Each pair is comprised of a first electrode (10a) and a second electrode (10b). The electrodes are patterned on a surface of a piezoelectric substrate (12). Each pair of electrodes may launch and receive various acoustic waves (AW), including a surface acoustic wave (SAW), and may also launch and receive several acoustic plate modes (APMs). The frequencies associated with each are functions of the transducer periodicity as well as the velocity of the particular AW in the chosen substrate material. An AW interaction region (13) exists between each pair of electrodes. Circuitry (20, 40) is used to launch, receive, and monitor the propagation characteristics of the AWs and may be configured in an intermittent measurement fashion or in a continuous measurement fashion. Perturbations to the AW velocity and attenuation are recorded at several frequencies and provide the sensor response.
NASA Astrophysics Data System (ADS)
Meredith, Roger W.; Kennedy, E. Ted; Malley, Dexter; Fisher, Robert A.; Brown, Robert; Stanic, Steve
2004-11-01
This paper is part of a series of papers describing acoustic coherence and fluctuations measurements made by the Naval Research Laboratory in the Gulf of Mexico near Panama City Beach, FL during June 2003. This paper presents low frequency (1-10 kHz) buried hydrophone measurements and preliminary results for two source-receiver ranges with grazing angles less than two degrees (realtive to the direct-path to the seafloor at the receiver location). Results focus on fluctuations after acoustic penetration into the sediment. These fluctuations are correlated with environmental influences.
NASA Astrophysics Data System (ADS)
Gallin, Louis-Jonardan; Farges, Thomas; Marchiano, Régis; Coulouvrat, François; Defer, Eric; Rison, William; Schulz, Wolfgang; Nuret, Mathieu
2016-04-01
In the framework of the European Hydrological Cycle in the Mediterranean Experiment project, a field campaign devoted to the study of electrical activity during storms took place in the south of France in 2012. An acoustic station composed of four microphones and four microbarometers was deployed within the coverage of a Lightning Mapping Array network. On the 26 October 2012, a thunderstorm passed just over the acoustic station. Fifty-six natural thunder events, due to cloud-to-ground and intracloud flashes, were recorded. This paper studies the acoustic reconstruction, in the low frequency range from 1 to 40 Hz, of the recorded flashes and their comparison with detections from electromagnetic networks. Concurrent detections from the European Cooperation for Lightning Detection lightning location system were also used. Some case studies show clearly that acoustic signal from thunder comes from the return stroke but also from the horizontal discharges which occur inside the clouds. The huge amount of observation data leads to a statistical analysis of lightning discharges acoustically recorded. Especially, the distributions of altitudes of reconstructed acoustic detections are explored in detail. The impact of the distance to the source on these distributions is established. The capacity of the acoustic method to describe precisely the lower part of nearby cloud-to-ground discharges, where the Lightning Mapping Array network is not effective, is also highlighted.
2015-02-11
A similar risk-based approach may be appropriate for deploying military personnel. e) If DoD were to consider implementing a large- scale pre...quality of existing spirometry programs prior to considering a larger scale pre-deployment effort. Identifying an accelerated decrease in spirometry...baseline spirometry on a wider scale . e) Conduct pre-deployment baseline spirometry if there is a significant risk of exposure to a pulmonary hazard based
NASA Astrophysics Data System (ADS)
Osada, Y.; Kido, M.; Ito, Y.; Iinuma, T.; Fujimoto, H.; Hino, R.
2014-12-01
Seafloor geodetic data, i.e. GPS/acoustic measurement and continuous seafloor pressure monitoring, brought important evidences showing that the 2011 Tohoku-oki earthquake (Mw 9.0) caused huge (> 50 m) coseismic slip near the Japan Trench. The postseismic behavior of the large slipped area is required to clarify to understand why large amount seismic slip could occur there. We started making direct-path acoustic ranging across the trench axis to reveal the convergence rate between the subducting Pacific and overriding continental plates. We expect the change of the baseline length across the trench axis, the plate boundary, reflects the slip rate at the shallow megathrust, which is difficult to estimate only from other geodetic observations largely affected by intraplate deformation caused by the postseismic viscoelastic relaxation process. To this end, we developed an ultra-deep seafloor acoustic ranging system. Our previous ranging systems have been designed to measure baseline length ~ 1 km and to be deployed up to 7,000 m water-depth (Osada et al., 2008, 2012). In order to realize the measurement across the Japan Trench, we improved this system to enhance range of acoustic ranging as well as operational depth of instruments. The improved system was designed to allow acoustic ranging up to 3 km and to be durable under the high-pressure equivalent to water depth of 9,000 m. In May 2013, we carried out a test deployment of the new ranging system. The system is composed of three seafloor instruments equipped with precision transponder (PXPs). Two of the PXPs were set on the landward slope of the Japan Trench, where large coseismic slip happened in 2011. Another PXP was deployed on the seaward side of the trench so that the baseline change associated with the slip on the plate boundary fault, if any, can be detected. Continuous records of baseline lengths were successfully obtained for four months. The repeatability of the distance measurements was about 20 mm for
Acoustic Modeling for Aqua Ventus I off Monhegan Island, ME
DOE Office of Scientific and Technical Information (OSTI.GOV)
Whiting, Jonathan M.; Hanna, Luke A.; DeChello, Nicole L.
2013-10-31
The DeepCwind consortium, led by the University of Maine, was awarded funding under the US Department of Energy’s Offshore Wind Advanced Technology Demonstration Program to develop two floating offshore wind turbines in the Gulf of Maine equipped with Goldwind 6 MW direct drive turbines, as the Aqua Ventus I project. The Goldwind turbines have a hub height of 100 m. The turbines will be deployed in Maine State waters, approximately 2.9 miles off Monhegan Island; Monhegan Island is located roughly 10 miles off the coast of Maine. In order to site and permit the offshore turbines, the acoustic output mustmore » be evaluated to ensure that the sound will not disturb residents on Monhegan Island, nor input sufficient sound levels into the nearby ocean to disturb marine mammals. This initial assessment of the acoustic output focuses on the sound of the turbines in air by modeling the assumed sound source level, applying a sound propagation model, and taking into account the distance from shore.« less
NASA Astrophysics Data System (ADS)
Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile
2015-03-01
The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.
Basic tasks for improving spectral-acoustic forecasting of dynamic phenomena in coal mines
NASA Astrophysics Data System (ADS)
Shadrin, A. V.; Kontrimas, A. A.
2017-09-01
A number of tasks for improving the spectral-acoustic method for forecasting dynamic phenomena and controlling stress condition in coalmines is considered. They are: considering the influence of a gas factor on the danger indicator, dependence of a relative pressure coefficient on the distance between the source and the receiver of the probing acoustic signal, correct selection of operating frequencies, the importance of developing the techniques for defining the critical value of the outburst danger index The influence of the rock mass stress condition ahead of the preliminary opening face on the relative pressure coefficient defined for installing the sound receiver in the wall of the opening behind the opening face is also justified in the article.
Acoustic sensors using microstructures tunable with energy other than acoustic energy
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.
Acoustic sensors using microstructures tunable with energy other than acoustic energy
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.
NASA Astrophysics Data System (ADS)
Gedamke, Jason; Robinson, Sarah M.
2010-05-01
A large scale, systematic, acoustic survey for whales and seals in eastern Antarctic waters was conducted in January-February 2006. During the BROKE-West survey of Southern Ocean waters between 30 and 80° E longitude, an acoustic survey was conducted to complement a traditional visual survey for marine mammal occurrence and distribution. As part of the survey, 145 DIFAR sonobuoys were deployed every 30' of latitude on north-south transects, and prior to CTD stations on the initial east-west transect. Underwater sound was analyzed for 70 minute samples from each sonobuoy. Blue whales were the most commonly recorded species, identified at 55 of the sonobuoy deployment sites. Other species recorded include: sperm (46 sites), fin (14), humpback (2), and sei (3) whales, and leopard (11) and Ross (17) seals. Large numbers of blue and sperm whales, and all Ross seals were detected on the westernmost two transects, which were the only transects of the survey with relatively extensive sea ice remaining off the continental shelf. Large numbers of blue whales were also detected in the more eastern waters of the survey off the Prydz Bay region, while two detections of pygmy blue whales represent the farthest south these whales have been recorded. Of the relatively few fin whale detections, most occurred in more northerly waters. Fin whale vocalizations from this region were distinctly different than those recorded elsewhere around Antarctica suggesting acoustic recordings may be useful to delineate regional or stock boundaries of this species. Previously undescribed sounds were attributed to Ross seals. Acoustic detections of these and leopard seal sounds indicate these animals venture further from their traditionally described distributions, with vocalizing leopard seals occurring much further north than might be expected. Overall, the results of the sonobuoy survey provide a measure of each species' relative spatial distribution over the survey area based on acoustic
2010-12-01
suggestions for reducing this burden to Department of Defense, Washington Headquarters Services , Directorate for Information Operations and Reports...NEAR THE NORTHERN EDGE RANGE. Recovery LONG-TERM MONITORING OF BLUE AND FIN WHALE ACOUSTIC SIGNALS FROM THE NORTH PACIFIC 1994-2009: COMPARISON OF...to poor weather conditions that precluded deployments near the shelf break. 4 Recovery All three moorings were safely recovered on
Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R
2016-01-07
The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium.
Psychiatric History, Deployments, and Potential Impacts of Mental Health Care in a Combat Theater.
Varga, Colleen M; Haibach, Michael A; Rowan, Anderson B; Haibach, Jeffrey P
2018-01-01
Increasing numbers of U.S. service members access mental health care while deployed and at home station. Multiple deployments carry with them a higher risk of exposure to combat as well as the impact of cumulative stressors associated with separation from family, hostile environments, and high operations tempo. However, mental health care resources continue to be underutilized, potentially because of higher levels of stigma regarding mental health care and concerns about career impact among service members. Some studies indicate that service members who have previously sought mental health care are likely to continue to do so proactively as needed. This study examined the associations between prior deployments, prior mental health treatment, and subsequent career-impacting recommendations (e.g., duty limitations and medical evacuation) among deployed service members seeking mental health care. Materials and. This study is a retrospective review of clinical records from three U.S. military Combat and Operational Stress Control units in Afghanistan. Data were drawn from the mental health records of 1,639 Army service members presenting for outpatient mental health services while deployed in Afghanistan from years 2006 to 2008. In an unadjusted logistic regression model, service members with at least one prior deployment had a 38% greater odds (odds ratio [OR] = 1.38, 95% confidence interval [95% CI] 1.06, 1.80; p < 0.05) of receiving career-impacting recommendations than those without a prior deployment. However, after adjusting for demographics (age, gender, marital status, rank, and military status), there was no association between prior deployments and career-impacting recommendations (OR = 1.06, 95% CI 0.78, 1.43; p = 0.716). In the second unadjusted model, service members with prior mental health treatment had a 57% lower odds (OR = 0.43, 95% CI 0.34, 0.56; p < 0.001) of receiving career-impacting recommendations than those without prior mental health treatment
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.
Zhang, Yingqiu; Xu, Qiang; Alós, Josep; Liu, Hui; Xu, Qinzeng; Yang, Hongsheng
2015-01-01
The recent miniaturization of acoustic tracking devices has allowed fishery managers and scientists to collect spatial and temporal data for sustainable fishery management. The spatial and temporal dimensions of fish behavior (movement and/or vertical migrations) are particularly relevant for rockfishes (Sebastes spp.) because most rockfish species are long-lived and have high site fidelity, increasing their vulnerability to overexploitation. In this study, we describe the short-term (with a tracking period of up to 46 d) spatial behavior, as determined by acoustic tracking, of the black rockfish Sebastes schlegelii, a species subject to overexploitation in the Yellow Sea of China. The average residence index (the ratio of detected days to the total period from release to the last detection) in the study area was 0.92 ± 0.13, and most of the tagged fish were detected by only one region of the acoustic receiver array, suggesting relatively high site fidelity to the study area. Acoustic tracking also suggested that this species is more frequently detected during the day than at night in our study area. However, the diel detection periodicity (24 h) was only evident for certain periods of the tracking time, as revealed by a continuous wavelet transform. The habitat selection index of tagged S. schlegelii suggested that S. schlegelii preferred natural reefs, mixed sand/artificial reef bottoms and mixed bottoms of boulder, cobble, gravel and artificial reefs. The preference of this species for the artificial reefs that were recently deployed in the study area suggests that artificial seascapes may be effective management tools to attract individuals. The vertical movement of tagged S. schlegelii was mostly characterized by bottom dwelling behavior, and there was high individual variability in the vertical migration pattern. Our results have important implications for S. schlegelii catchability, the implementation of marine protected areas, and the identification of key
Gibbs, Deborah A; Clinton-Sherrod, A Monique; Johnson, Ruby E
2012-10-01
Deployment represents a significant potential strain on military families. The impact of postdeployment stresses may be increased if family coping resources are diminished by returning service members' physical injuries, mental health issues, or substance abuse. This article examines the health and mental health correlates of self-reported concerns regarding interpersonal conflict among married soldiers following return from deployment and the likelihood that soldiers acknowledging such concerns are referred to counseling services. Among 20,166 married Army soldiers completing Post-Deployment Health Reassessments, 18% reported having experienced serious interpersonal conflict with their spouse, family members, close friends, or coworkers. Results indicate that interpersonal conflict was more common among those who reported health problems, depression, post-traumatic stress disorder, and alcohol abuse. Among soldiers reporting interpersonal conflict and not already receiving services, 11% were referred to service. Findings support the need to communicate with soldiers and their spouses about the availability of services following return from deployment and to continue efforts to reduce stigma associated with seeking treatment.
Acoustic Green's function extraction in the ocean
NASA Astrophysics Data System (ADS)
Zang, Xiaoqin
data were collected in a 100-meter deep coastal ocean environment and a 600-meter deep ocean environment. In the coastal ocean environment, the collected noise data were processed by coherently stacking five days of cross-correlation functions between pairs of hydrophones separated by 5 km, 10 km and 15 km, respectively. NCF waveforms were modeled using the KRAKEN normal mode model, with the difference between the NCFs and the acoustic GFs quantified by a weighting function. Through waveform inversion of NCFs, an optimal geoacoustic model was obtained by minimizing the two-norm misfit between the simulation and the measurement. Using a simulated time-reversal mirror, the extracted GF was back propagated from the receiver location to the virtual source, and a strong focus was found in the vicinity of the source, which provides additional support for the optimality of the aforementioned geoacoustic model. With the extracted GF, dispersion in experimental shallow water environment was visualized in the time-frequency representation. Normal modes of GFs were separated using the time-warping transformation. By separating the modes in the frequency domain of the time-warped signal, we isolated modal arrivals and reconstructed the NCF by summing up the isolated modes, thereby significantly improving the signal-to-noise ratio of NCFs. Finally, these reconstructed NCFs were employed to estimate the depth-averaged current speed in the Florida Straits, based on an effective sound speed approximation. In the mid-deep ocean environment, the noise data were processed using the same noise interferometry method, but the obtained NCFs were not as good as those in the coastal ocean environment. Several highly possible reasons of the difference in the noise interferometry performance were investigated and discussed. The first one is the noise source composition, which is different in the spectrograms of noise records in two environments. The second is strong ocean current variability
NASA Astrophysics Data System (ADS)
Ramos, António L. L.; Holm, Sverre; Gudvangen, Sigmund; Otterlei, Ragnvald
2013-06-01
Counter sniper systems rely on the detection and parameter estimation of the shockwave and the muzzle blast in order to determine the sniper location. In real-world situations, these acoustical signals can be disturbed by natural phenomena like weather and climate conditions, multipath propagation effect, and background noise. While some of these issues have received some attention in recent publications with application to gunshot acoustics, the multipath propagation phenomenon whose effect can not be neglected, specially in urban environments, has not yet been discussed in details in the technical literature in the same context. Propagating sound waves can be reflected at the boundaries in the vicinity of sound sources or receivers, whenever there is a difference in acoustical impedance between the reflective material and the air. Therefore, the received signal can be composed of a direct-path signal plus N scaled delayed copies of that signal. This paper presents a discussion on the multipath propagation effect and its impact on the performance and reliability of sniper positioning systems. In our formulation, propagation models for both the shockwave and the muzzle blast are considered and analyzed. Conclusions following the theoretical analysis of the problem are fully supported by actual gunshots acoustical signatures.
Post deployment care for returning combat veterans.
Spelman, Juliette F; Hunt, Stephen C; Seal, Karen H; Burgo-Black, A Lucile
2012-09-01
Since September 11, 2001, 2.4 million military personnel have deployed to Iraq and Afghanistan. To date, roughly 1.44 million have separated from the military and approximately 772,000 of these veterans have used VA health care. Combat deployments impact the physical, psychological, and social health of veterans. Given that many veterans are receiving care from non-VA providers, it is important that all community health care workers be familiar with the unique health care needs of this patient population, which include injuries associated with blast exposures (including mild traumatic brain injury), as well as a variety of mental health conditions, such as post-traumatic stress disorder. Other important health concerns are chronic musculoskeletal pain, medically unexplained symptoms, sequelae of environmental exposures, depression, suicide, substance abuse, sleep disturbances, and impairments in family, occupational and social functioning. Elevated rates of hypertension and tobacco use remind us that deployment may result not only in immediate impacts on health, but also increase risk for chronic disease, contributing to a growing public health burden. This paper provides a comprehensive review of these health concerns and offers practical management guidelines for primary care providers. In light of relationships between physical, psychological and psychosocial concerns in this population, we recommend an interdisciplinary approach to care directed toward mitigating the long-term health impacts of combat.
Real-time reporting of baleen whale passive acoustic detections from ocean gliders.
Baumgartner, Mark F; Fratantoni, David M; Hurst, Thomas P; Brown, Moira W; Cole, Tim V N; Van Parijs, Sofie M; Johnson, Mark
2013-09-01
In the past decade, much progress has been made in real-time passive acoustic monitoring of marine mammal occurrence and distribution from autonomous platforms (e.g., gliders, floats, buoys), but current systems focus primarily on a single call type produced by a single species, often from a single location. A hardware and software system was developed to detect, classify, and report 14 call types produced by 4 species of baleen whales in real time from ocean gliders. During a 3-week deployment in the central Gulf of Maine in late November and early December 2012, two gliders reported over 25,000 acoustic detections attributed to fin, humpback, sei, and right whales. The overall false detection rate for individual calls was 14%, and for right, humpback, and fin whales, false predictions of occurrence during 15-min reporting periods were 5% or less. Transmitted pitch tracks--compact representations of sounds--allowed unambiguous identification of both humpback and fin whale song. Of the ten cases when whales were sighted during aerial or shipboard surveys and a glider was within 20 km of the sighting location, nine were accompanied by real-time acoustic detections of the same species by the glider within ±12 h of the sighting time.
Surface Acoustic Wave Tag-Based Coherence Multiplexing
NASA Technical Reports Server (NTRS)
Youngquist, Robert C. (Inventor); Malocha, Donald (Inventor); Saldanha, Nancy (Inventor)
2016-01-01
A surface acoustic wave (SAW)-based coherence multiplexing system includes SAW tags each including a SAW transducer, a first SAW reflector positioned a first distance from the SAW transducer and a second SAW reflector positioned a second distance from the SAW transducer. A transceiver including a wireless transmitter has a signal source providing a source signal and circuitry for transmitting interrogation pulses including a first and a second interrogation pulse toward the SAW tags, and a wireless receiver for receiving and processing response signals from the SAW tags. The receiver receives scrambled signals including a convolution of the wideband interrogation pulses with response signals from the SAW tags and includes a computing device which implements an algorithm that correlates the interrogation pulses or the source signal before transmitting against the scrambled signals to generate tag responses for each of the SAW tags.
NASA Astrophysics Data System (ADS)
Liu, Yang; D'Angelo, Ralph M.; Sinha, Bikash K.; Zeroug, Smaine
2017-02-01
Modeling and understanding the complex elastic-wave physics prevalent in solid-fluid cylindrically-layered structures is of importance in many NDE fields, and most pertinently in the domain of well integrity evaluation of cased holes in the oil and gas industry. Current sonic measurements provide viable techniques for well integrity evaluation yet their practical effectiveness is hampered by the current lack of knowledge of acoustic wave fields particularly in complicated cased-hole geometry where for instance two or more nested steel strings are present in the borehole. In this article, we propose and implement a Sweeping Frequency Finite Element Method (SFFEM) for acoustic guided waves simulation in complex geometries that include double steel strings cemented to each other and to the formation and where the strings may be non-concentric. Transient dynamic finite element models are constructed with sweeping frequency signals being applied as the excitation sources. The sources and receivers disposition simulate current sonic measurement tools deployed in the oilfield. Synthetic wavetrains are recorded and processed with modified matrix pencil method to isolate both the dispersive and non-dispersive propagating guided wave modes. Scaled experiments of fluid-filled double strings with dimensions mimicking the real ones encountered in the field have also been carried out to generate reference data. A comparison of the experimental and numerical results indicates that the SFFEM is capable of accurately reproducing the rich and intricate higher-order multiple wave fields observed experimentally in the fluid-filled double string geometries.
Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO
NASA Technical Reports Server (NTRS)
Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.
2011-01-01
Evaluating the impact of radio frequency transmission in vehicle fairings is important to electromagnetically sensitive spacecraft. This study employs the multilevel fast multipole method (MLFMM) from a commercial electromagnetic tool, FEKO, to model the fairing electromagnetic environment in the presence of an internal transmitter with improved accuracy over industry applied techniques. This fairing model includes material properties representative of acoustic blanketing commonly used in vehicles. Equivalent surface material models within FEKO were successfully applied to simulate the test case. Finally, a simplified model is presented using Nicholson Ross Weir derived blanket material properties. These properties are implemented with the coated metal option to reduce the model to one layer within the accuracy of the original three layer simulation.
Passive acoustic monitoring of Cook Inlet beluga whales (Delphinapterus leucas).
Lammers, Marc O; Castellote, Manuel; Small, Robert J; Atkinson, Shannon; Jenniges, Justin; Rosinski, Anne; Oswald, Julie N; Garner, Chris
2013-09-01
The endangered beluga whale (Delphinapterus leucas) population in Cook Inlet, AK faces threats from a variety of anthropogenic factors, including coastal development, oil and gas exploration, vessel traffic, and military activities. To address existing gaps in understanding about the occurrence of belugas in Cook Inlet, a project was developed to use passive acoustic monitoring to document the year-round distribution of belugas, as well as killer whales (Orcinus orca), which prey on belugas. Beginning in June 2009, ten moorings were deployed throughout the Inlet and refurbished every two to eight months. Despite challenging conditions consisting of strong tidal currents carrying debris and seasonal ice cover, 83% of mooring deployments were successfully recovered. Noise from water flow, vessel traffic, and/or industrial activities was present at several sites, potentially masking some signals. However, belugas were successfully detected at multiple locations. Detections were relatively common in the upper inlet and less common or absent at middle and lower inlet locations. Killer whale signals were also recorded. Some seasonal variability in the occurrence of both belugas and killer whales was evident.
Acoustic energy harvesting based on a planar acoustic metamaterial
NASA Astrophysics Data System (ADS)
Qi, Shuibao; Oudich, Mourad; Li, Yong; Assouar, Badreddine
2016-06-01
We theoretically report on an innovative and practical acoustic energy harvester based on a defected acoustic metamaterial (AMM) with piezoelectric material. The idea is to create suitable resonant defects in an AMM to confine the strain energy originating from an acoustic incidence. This scavenged energy is converted into electrical energy by attaching a structured piezoelectric material into the defect area of the AMM. We show an acoustic energy harvester based on a meta-structure capable of producing electrical power from an acoustic pressure. Numerical simulations are provided to analyze and elucidate the principles and the performances of the proposed system. A maximum output voltage of 1.3 V and a power density of 0.54 μW/cm3 are obtained at a frequency of 2257.5 Hz. The proposed concept should have broad applications on energy harvesting as well as on low-frequency sound isolation, since this system acts as both acoustic insulator and energy harvester.
Two-dimensional arbitrarily shaped acoustic cloaks composed of homogeneous parts
NASA Astrophysics Data System (ADS)
Li, Qi; Vipperman, Jeffrey S.
2017-10-01
Acoustic cloaking is an important application of acoustic metamaterials. Although the topic has received much attention, there are a number of areas where contributions are needed. In this paper, a design method for producing acoustic cloaks with arbitrary shapes that are composed of homogeneous parts is presented. The cloak is divided into sections, each of which, in turn, is further divided into two parts, followed by the application of transformation acoustics to derive the required properties for cloaking. With the proposed mapping relations, the properties of each part of the cloak are anisotropic but homogeneous, which can be realized using two alternating layers of homogeneous and isotropic materials. A hexagonal and an irregular cloak are presented as design examples. The full wave simulations using COMSOL Multiphysics finite element software show that the cloaks function well at reducing reflections and shadows. The variation of the cloak properties is investigated as a function of three important geometric parameters used in the transformations. A balance can be found between cloaking performance and materials properties that are physically realizable.
Evidence for acoustic communication among bottom foraging humpback whales
Parks, Susan E.; Cusano, Dana A.; Stimpert, Alison K.; Weinrich, Mason T.; Friedlaender, Ari S.; Wiley, David N.
2014-01-01
Humpback whales (Megaptera novaeangliae), a mysticete with a cosmopolitan distribution, demonstrate marked behavioural plasticity. Recent studies show evidence of social learning in the transmission of specific population level traits ranging from complex singing to stereotyped prey capturing behaviour. Humpback whales have been observed to employ group foraging techniques, however details on how individuals coordinate behaviour in these groups is challenging to obtain. This study investigates the role of a novel broadband patterned pulsed sound produced by humpback whales engaged in bottom-feeding behaviours, referred to here as a ‘paired burst' sound. Data collected from 56 archival acoustic tag deployments were investigated to determine the functional significance of these signals. Paired burst sound production was associated exclusively with bottom feeding under low-light conditions, predominantly with evidence of associated conspecifics nearby suggesting that the sound likely serves either as a communicative signal to conspecifics, a signal to affect prey behaviour, or possibly both. This study provides additional evidence for individual variation and phenotypic plasticity of foraging behaviours in humpback whales and provides important evidence for the use of acoustic signals among foraging individuals in this species. PMID:25512188
Evidence for acoustic communication among bottom foraging humpback whales.
Parks, Susan E; Cusano, Dana A; Stimpert, Alison K; Weinrich, Mason T; Friedlaender, Ari S; Wiley, David N
2014-12-16
Humpback whales (Megaptera novaeangliae), a mysticete with a cosmopolitan distribution, demonstrate marked behavioural plasticity. Recent studies show evidence of social learning in the transmission of specific population level traits ranging from complex singing to stereotyped prey capturing behaviour. Humpback whales have been observed to employ group foraging techniques, however details on how individuals coordinate behaviour in these groups is challenging to obtain. This study investigates the role of a novel broadband patterned pulsed sound produced by humpback whales engaged in bottom-feeding behaviours, referred to here as a 'paired burst' sound. Data collected from 56 archival acoustic tag deployments were investigated to determine the functional significance of these signals. Paired burst sound production was associated exclusively with bottom feeding under low-light conditions, predominantly with evidence of associated conspecifics nearby suggesting that the sound likely serves either as a communicative signal to conspecifics, a signal to affect prey behaviour, or possibly both. This study provides additional evidence for individual variation and phenotypic plasticity of foraging behaviours in humpback whales and provides important evidence for the use of acoustic signals among foraging individuals in this species.
Panel acoustic contribution analysis.
Wu, Sean F; Natarajan, Logesh Kumar
2013-02-01
Formulations are derived to analyze the relative panel acoustic contributions of a vibrating structure. The essence of this analysis is to correlate the acoustic power flow from each panel to the radiated acoustic pressure at any field point. The acoustic power is obtained by integrating the normal component of the surface acoustic intensity, which is the product of the surface acoustic pressure and normal surface velocity reconstructed by using the Helmholtz equation least squares based nearfield acoustical holography, over each panel. The significance of this methodology is that it enables one to analyze and rank relative acoustic contributions of individual panels of a complex vibrating structure to acoustic radiation anywhere in the field based on a single set of the acoustic pressures measured in the near field. Moreover, this approach is valid for both interior and exterior regions. Examples of using this method to analyze and rank the relative acoustic contributions of a scaled vehicle cabin are demonstrated.
Deployable Soft Composite Structures.
Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon
2016-02-19
Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel.
Deployable Soft Composite Structures
Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon
2016-01-01
Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel. PMID:26892762
Underwater Acoustic Transponders Tracking While Mapping With A Multibeam Echo-Sounder
NASA Astrophysics Data System (ADS)
de Moustier, C. P.; Franzheim, A.; Testa, W.; Burns, J. M.; Foy, R.
2010-12-01
A 160 kHz multibeam echo-sounder was used to interrogate and receive the replies from custom-built miniature underwater acoustic transponders attached to the carapace of king crabs in Womens Bay, Alaska. This new application of multibeam echo-sounders combines acoustic tracking and mapping, thus providing environmental context to the tracking information. Each transponder replies with its own coded sequence that stands out from other echoes received by the sonar. Range and bearing of the replies from multiple transponders can be obtained in a single sonar ping. The king crab experiment was done in 25-35 m of water depth, and the system was successfully tested without animals at 190 m depth. Work supported by NOAA's Undersea Research Program Grant G4768, with field work support from NOAA-NMFS/AFSC/RACE and Electronic Navigation Ltd.
NASA Astrophysics Data System (ADS)
Mante, Pierre-Adrien; Stoumpos, Constantinos C.; Kanatzidis, Mercouri G.; Yartsev, Arkady
2017-02-01
Despite the great amount of attention CH3NH3PbI3 has received for its solar cell application, intrinsic properties of this material are still largely unknown. Mobility of charges is a quintessential property in this aspect; however, there is still no clear understanding of electron transport, as reported values span over three orders of magnitude. Here we develop a method to measure the electron and hole deformation potentials using coherent acoustic phonons generated by femtosecond laser pulses. We apply this method to characterize a CH3NH3PbI3 single crystal. We measure the acoustic phonon properties and characterize electron-acoustic phonon scattering. Then, using the deformation potential theory, we calculate the carrier intrinsic mobility and compare it to the reported experimental and theoretical values. Our results reveal high electron and hole mobilities of 2,800 and 9,400 cm2 V-1 s-1, respectively. Comparison with literature values of mobility demonstrates the potential role played by polarons in charge transport in CH3NH3PbI3.
Mante, Pierre-Adrien; Stoumpos, Constantinos C.; Kanatzidis, Mercouri G.; ...
2017-02-08
The intrinsic properties of CH 3NH 3PbI 3 are still largely unknown in spite of the great amount of attention it has received for its solar cell application. Mobility of charges is a quintessential property in this aspect; however, there is still no clear understanding of electron transport, as reported values span over three orders of magnitude. Here we develop a method to measure the electron and hole deformation potentials using coherent acoustic phonons generated by femtosecond laser pulses. Furthermore, we apply this method to characterize a CH 3NH 3PbI 3 single crystal.We measure the acoustic phonon properties and characterizemore » electron-acoustic phonon scattering. Then, using the deformation potential theory, we calculate the carrier intrinsic mobility and compare it to the reported experimental and theoretical values. These results reveal high electron and hole mobilities of 2,800 and 9,400 cm 2V -1 s -1 , respectively. Comparison with literature values of mobility demonstrates the potential role played by polarons in charge transport in CH 3NH 3PbI 3.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Mante, Pierre-Adrien; Stoumpos, Constantinos C.; Kanatzidis, Mercouri G.
The intrinsic properties of CH 3NH 3PbI 3 are still largely unknown in spite of the great amount of attention it has received for its solar cell application. Mobility of charges is a quintessential property in this aspect; however, there is still no clear understanding of electron transport, as reported values span over three orders of magnitude. Here we develop a method to measure the electron and hole deformation potentials using coherent acoustic phonons generated by femtosecond laser pulses. Furthermore, we apply this method to characterize a CH 3NH 3PbI 3 single crystal.We measure the acoustic phonon properties and characterizemore » electron-acoustic phonon scattering. Then, using the deformation potential theory, we calculate the carrier intrinsic mobility and compare it to the reported experimental and theoretical values. These results reveal high electron and hole mobilities of 2,800 and 9,400 cm 2V -1 s -1 , respectively. Comparison with literature values of mobility demonstrates the potential role played by polarons in charge transport in CH 3NH 3PbI 3.« less
Is dust acoustic wave a new plasma acoustic mode?
DOE Office of Scientific and Technical Information (OSTI.GOV)
Dwivedi, C.B.
1997-09-01
In this Brief Communication, the claim of the novelty of the dust acoustic wave in a dusty plasma within the constant dust charge model is questioned. Conceptual lacunas behind the claim have been highlighted and appropriate physical arguments have been forwarded against the claim. It is demonstrated that the so-called dust acoustic wave could better be termed as a general acoustic fluctuation response with a dominant characteristic feature of the acoustic-like mode (ALM) fluctuation response reported by Dwivedi {ital et al.} [J. Plasma Phys. {bold 41}, 219 (1989)]. It is suggested that both correct and more usable nomenclature of themore » ALM should be the so-called acoustic mode. {copyright} {ital 1997 American Institute of Physics.}« less
Towards deployable meta-implants.
Bobbert, F S L; Janbaz, S; Zadpoor, A A
2018-06-07
Meta-biomaterials exhibit unprecedented or rare combinations of properties not usually found in nature. Such unusual mechanical, mass transport, and biological properties could be used to develop novel categories of orthopedic implants with superior performance, otherwise known as meta-implants. Here, we use bi-stable elements working on the basis of snap-through instability to design deployable meta-implants. Deployable meta-implants are compact in their retracted state, allowing them to be brought to the surgical site with minimum invasiveness. Once in place, they are deployed to take their full-size load-bearing shape. We designed five types of meta-implants by arranging bi-stable elements in such a way to obtain a radially-deployable structure, three types of auxetic structures, and an axially-deployable structure. The intermediate stable conditions ( i.e. multi-stability features), deployment force, and stiffness of the meta-implants were found to be strongly dependent on the geometrical parameters of the bi-stable elements as well as on their arrangement.
Prediction of Acoustic Environments from Horizontal Rocket Firings
NASA Technical Reports Server (NTRS)
Giacomoni, Clothilde
2014-01-01
highly directional noise radiation. Tam3 has proposed a model to predict the acoustic environment due to jets and while it works extremely well for jets, it was found to be inappropriate for rockets8. A model to predict the acoustic environment due to a launch vehicle in the far-field which incorporates concepts from both Eldred and Tam was created. This was done using five sets of horizontally fired rocket data, obtained between 2008 and 2012. Three of these rockets use solid propellant and two use liquid propellant. Through scaling analysis, it is shown that liquid and solid rocket motors exhibit similar spectra at similar amplitudes. This model is accurate for these five data sets within 5 dB of the measured data for receiver angles of 30deg to 160deg (with respect to the downstream exhaust centerline). The model uses the following vehicle parameters: nozzle exit diameter and velocity, radial distance from source to receiver, receiver angle, mass flow rate, and acoustic efficiency.
Stimpert, A. K.; DeRuiter, S. L.; Southall, B. L.; Moretti, D. J.; Falcone, E. A.; Goldbogen, J. A.; Friedlaender, A.; Schorr, G. S.; Calambokidis, J.
2014-01-01
Beaked whales are hypothesized to be particularly sensitive to anthropogenic noise, based on previous strandings and limited experimental and observational data. However, few species have been studied in detail. We describe the underwater behavior of a Baird's beaked whale (Berardius bairdii) from the first deployment of a multi-sensor acoustic tag on this species. The animal exhibited shallow (23 ± 15 m max depth), intermediate (324 ± 49 m), and deep (1138 ± 243 m) dives. Echolocation clicks were produced with a mean inter-click interval of approximately 300 ms and peak frequency of 25 kHz. Two deep dives included presumed foraging behavior, with echolocation pulsed sounds (presumed prey capture attempts) associated with increased maneuvering, and sustained inverted swimming during the bottom phase of the dive. A controlled exposure to simulated mid-frequency active sonar (3.5–4 kHz) was conducted 4 hours after tag deployment, and within 3 minutes of exposure onset, the tagged whale increased swim speed and body movement, and continued to show unusual dive behavior for each of its next three dives, one of each type. These are the first data on the acoustic foraging behavior in this largest beaked whale species, and the first experimental demonstration of a response to simulated sonar. PMID:25391309
Bouk, Safdar Hussain; Ahmed, Syed Hassan; Park, Kyung-Joon; Eun, Yongsoon
2017-09-26
Underwater Acoustic Sensor Network (UASN) comes with intrinsic constraints because it is deployed in the aquatic environment and uses the acoustic signals to communicate. The examples of those constraints are long propagation delay, very limited bandwidth, high energy cost for transmission, very high signal attenuation, costly deployment and battery replacement, and so forth. Therefore, the routing schemes for UASN must take into account those characteristics to achieve energy fairness, avoid energy holes, and improve the network lifetime. The depth based forwarding schemes in literature use node's depth information to forward data towards the sink. They minimize the data packet duplication by employing the holding time strategy. However, to avoid void holes in the network, they use two hop node proximity information. In this paper, we propose the Energy and Depth variance-based Opportunistic Void avoidance (EDOVE) scheme to gain energy balancing and void avoidance in the network. EDOVE considers not only the depth parameter, but also the normalized residual energy of the one-hop nodes and the normalized depth variance of the second hop neighbors. Hence, it avoids the void regions as well as balances the network energy and increases the network lifetime. The simulation results show that the EDOVE gains more than 15 % packet delivery ratio, propagates 50 % less copies of data packet, consumes less energy, and has more lifetime than the state of the art forwarding schemes.
A deployable .015 inch diameter wire antenna
NASA Technical Reports Server (NTRS)
Dibiasi, L.
1979-01-01
This mechanism was developed to dispense a small diameter wire which serves as a receiving antenna for electric field measurements on an Earth orbiting satellite. The antenna is deployed radially from a spinning satellite. A brushless dc motor drives a storage spool to dispense the wire at a controlled rate. Centrifugal force, acting on a mass attached to the end of the wire, keeps the wire in the radial position. The mechanism design, testing, and performance characteristics are discussed. Finally, operational data of the mechanism while in orbit are presented.
NASA Technical Reports Server (NTRS)
Steinetz, Bruce M. (Inventor)
2006-01-01
The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.
NASA Technical Reports Server (NTRS)
Steinetz, Bruce M. (Inventor)
2006-01-01
The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.
Whitten, Pamela; Holtz, Bree; Laplante, Carolyn; Alverson, Dale; Krupinski, Elizabeth
2010-12-01
the goal of this study was to provide an independent and objective evaluation of the implementation of the Federal Communications Commission's Rural Health Care Pilot Program. thirty-nine of the programs that were provided funding through this program were interviewed and asked about their project deployment, network planning, and the involvement of their state in implementation. RESULTS showed that programs recruited project team members from a variety of fields to fulfill different roles. Network partners were often chosen because they were stakeholders in the outcome of the project and because they had a past working relationship with the grant-receiving programs. In terms of deployment, many programs had made progress in filling out necessary paperwork and were tracking milestones, but had experienced changes since first receiving funding, such as losing participants. Additionally, many encountered challenges that inhibited deployment, such as coping with rule fluctuations. Many of the programs received support from their respective state governments in project development, often through matching funds, but few states were involved in the actual management of projects. as rural healthcare facilities often lack the information technology infrastructure compared with many urban facilities, it is important to understand the implementation process for programs such as the Rural Health Care Pilot Program and to examine what contributes to progress, stagnation, or disintegration. Although the programs reported some success, almost all had encountered challenges that inhibited implementation. A follow-up study is planned to further investigate deployment and determine the implications of Federal Communications Commission funding.
NASA Technical Reports Server (NTRS)
Shafer, Michael W.; Gallon, John C.; Rivellini, Tommaso P.
2011-01-01
The landing scheme for NASA's next-generation Mars rover will encompass a novel landing technique (see figure). The rover will be lowered from a rocket-powered descent stage and then placed onto the surface while hanging from three bridles. Communication between the rover and descent stage will be maintained through an electrical umbilical cable, which will be deployed in parallel with structural bridles. The -inch (13-mm) umbilical cable contains a Kevlar rope core, around which wires are wrapped to create a cable. This cable is helically coiled between two concentric truncated cones. It is deployed by pulling one end of the cable from the cone. A retractable mechanism maintains tension on the cable after deployment. A break-tie tethers the umbilical end attached to the rover even after the cable is cut after touchdown. This break-tie allows the descent stage to develop some velocity away from the rover prior to the cable releasing from the rover deck, then breaks away once the cable is fully extended. The descent stage pulls the cable up so that recontact is not made. The packaging and deployment technique can store a long length of cable in a relatively small volume while maintaining compliance with the minimum bend radius requirement for the cable being deployed. While the packaging technique could be implemented without the use of break-ties, they were needed in this design due to the vibratory environment and the retraction required by the cable. The break-ties used created a series of load-spikes in the deployment signature. The load spikes during the deployment of the initial three coils of umbilical showed no increase between the different temperature trials. The cold deployment did show an increased load requirement for cable extraction in the region where no break-ties were used. This increase in cable drag was superimposed on the loads required to rupture the last set of break-ties, and as such, these loads saw significant increase when compared to
High-acoustic-impedance tantalum oxide layers for insulating acoustic reflectors.
Capilla, Jose; Olivares, Jimena; Clement, Marta; Sangrador, Jesús; Iborra, Enrique; Devos, Arnaud
2012-03-01
This work describes the assessment of the acoustic properties of sputtered tantalum oxide films intended for use as high-impedance films of acoustic reflectors for solidly mounted resonators operating in the gigahertz frequency range. The films are grown by sputtering a metallic tantalum target under different oxygen and argon gas mixtures, total pressures, pulsed dc powers, and substrate biases. The structural properties of the films are assessed through infrared absorption spectroscopy and X-ray diffraction measurements. Their acoustic impedance is assessed by deriving the mass density from X-ray reflectometry measurements and the acoustic velocity from picosecond acoustic spectroscopy and the analysis of the frequency response of the test resonators.
Long-term measurements of acoustic background noise in very deep sea
NASA Astrophysics Data System (ADS)
Riccobene, G.; NEMO Collaboration
2009-06-01
The NEMO (NEutrino Mediterranean Observatory) Collaboration installed, 25 km E offshore the port of Catania (Sicily) at 2000 m depth, an underwater laboratory to perform long-term tests of prototypes and new technologies for an underwater high energy neutrino km-scale detector in the Mediterranean Sea. In this framework the Collaboration deployed and successfully operated for about two years, starting from January 2005, an experimental apparatus for on-line monitoring of deep-sea noise. The station was equipped with four hydrophones and it is operational in the range 30 Hz-43 kHz. This interval of frequencies matches the range suitable for the proposed acoustic detection technique of high energy neutrinos. Hydrophone signals were digitized underwater at 96 kHz sampling frequency and 24 bits resolution. The stored data library, consisting of more than 2000 h of recordings, is a unique tool to model underwater acoustic noise at large depth, to characterize its variations as a function of environmental parameters, biological sources and human activities (ship traffic, etc.), and to determine the presence of cetaceans in the area.
NASA Astrophysics Data System (ADS)
Lynch, J. F.; Gross, T. F.; Sherwood, C. R.; Irish, J. D.; Brumley, B. H.
1997-04-01
During the 1988-1989 Sediment Transport Events on Shelves and Slopes (STRESS) experiment, a 1-MHz acoustic backscatter system (ABSS), deployed in 90 m of water off the California coast measured vertical profiles of suspended sediment concentration from 1.5 to (nominally) 26 meters above bottom (m.a.b.). An 8-week-long time series was obtained, showing major sediment transport events (storms) in late December and early January. Comparison of the acoustics measurements from 1.5 m.a.b. are made with optical backscatter system (OBS) concentration estimates lower in the boundary layer (0.25 m.a.b.). Correlations between ABSS and OBS concentration measurements and the boundary layer forcing functions (waves, currents, and their non-linear interaction) provided a variety of insights into the nature of the sediment transport of the STRESS site. Transport rates and integrated transport are seen to be dominated by the largest storm events.
NASA Technical Reports Server (NTRS)
Shaffer, Joe R.; Headley, David E.
1993-01-01
Compact storable components expand to create large shelter. Fully deployed structure provides large, unobstructed bay. Deployed trusses support wall and roof blankets. Provides temporary cover for vehicles, people, and materials. Terrestrial version used as garage, hangar, or large tent.
Acoustic Wave Guiding by Reconfigurable Tessellated Arrays
NASA Astrophysics Data System (ADS)
Zou, Chengzhe; Lynd, Danielle T.; Harne, Ryan L.
2018-01-01
The reconfiguration of origami tessellations is a prime vehicle to harness for adapting system properties governed by a structural form. While the knowledge of mechanical property changes associated with origami tessellation folding has been extensively built up, the opportunities to integrate other physics into a framework of tessellated, adaptive structures remain to be fully exploited. Acoustics appears to be a prime domain to marry with origami science. Specifically, deep technical analogies are revealed between wave-guiding properties achieved via digital methods that virtually reposition array elements and the actual repositioning of facets by folding origami-inspired tessellations. Here we capitalize on this analogy to investigate acoustic arrays established upon facet layouts of origami-inspired tessellations. We show that a concept of reconfigurable tessellated arrays may guide waves more effectively than traditional digitally phased arrays using fewer transducer elements. Moreover, we show that the refinement of tessellated arrays trends to the ideal case of classical wave radiators or receivers grounded in principles of geometrical acoustics. By linear wave physics shared among myriad scientific disciplines and across orders of magnitude in length scale, these discoveries may cultivate numerous opportunities for wave-guiding adaptive structures inspired by low-dimensional origami tessellations.
Deployment-related Respiratory Issues.
Morris, Michael J; Rawlins, Frederic A; Forbes, Damon A; Skabelund, Andrew J; Lucero, Pedro F
2016-01-01
Military deployment to Southwest Asia since 2003 in support of Operations Enduring Freedom/Iraqi Freedom/New Dawn has presented unique challenges from a pulmonary perspective. Various airborne hazards in the deployed environment include suspended geologic dusts, burn pit smoke, vehicle exhaust emissions, industrial air pollution, and isolated exposure incidents. These exposures may give rise to both acute respiratory symptoms and in some instances development of chronic lung disease. While increased respiratory symptoms during deployment are well documented, there is limited data on whether inhalation of airborne particulate matter is causally related to an increase in either common or unique pulmonary diseases. While disease processes such as acute eosinophilic pneumonia and exacerbation of preexisting asthma have been adequately documented, there is significant controversy surrounding the potential effects of deployment exposures and development of rare pulmonary disorders such as constrictive bronchiolitis. The role of smoking and related disorders has yet to be defined. This article presents the current evidence for deployment-related respiratory symptoms and ongoing Department of Defense studies. Further, it also provides general recommendations for evaluating pulmonary health in the deployed military population.
Fiber-optic hydrophone array for acoustic surveillance in the littoral
NASA Astrophysics Data System (ADS)
Hill, David; Nash, Phillip
2005-05-01
We describe a fibre-optic hydrophone array system architecture that can be tailored to meet the underwater acoustic surveillance requirements of the military, counter terrorist and customs authorities in protecting ports and harbours, offshore production facilities or coastal approaches. Physically the fibre-optic hydrophone array is in the form of a lightweight cable, enabling rapid deployment from a small vessel. Based upon an optical architecture of time and wavelength multiplexed interferometric hydrophones, the array is comprised of a series of hydrophone sub-arrays. Using multiple sub-arrays, extended perimeters many tens of kilometres in length can be monitored. Interrogated via a long (~50km) optical fibre data link, the acoustic date is processed using the latest open architecture sonar processing platform, ensuring that acoustic targets below, on and above the surface are detected, tracked and classified. Results obtained from an at sea trial of a 96-channel hydrophone array are given, showing the passive detection and tracking of a diver, small surface craft and big ocean going ships beyond the horizon. Furthermore, we describe how the OptaMarine fibre-optic hydrophone array fits into an integrated multi-layered approach to port and harbour security consisting of active sonar for diver detection and hull imaging, as well as thermal imaging and CCTV for surface monitoring. Finally, we briefly describe a complimentary land perimeter intruder detection system consisting of an array of fibre optic accelerometers.
Bottom Interaction in Long Range Acoustic Propagation
2006-09-30
Pacific Ocean utilizing controlled sources and vertical and horizontal receiver arrays . Broadband sources are considered with typical center...The LOAPEX (Long-range Ocean Acoustic Propagation Experiment) vertical line arrays (VLA) are described on page 1 of the LOAPEX cruise report: " The...hydrophone arrays on the two combined VLAs covered most of the 5-km water column. We refer to one of the VLAs as the deep VLA (DVLA), located at
Carter, S. P.; Loew, B.; Allen, E. S.; Osborne, L.; Stanley, S. M.; Markman, H. J.
2015-01-01
Military spouses often have concerns regarding the impact of their communication on soldiers during deployment. However, literature is mixed regarding how communication between soldiers and spouses may impact soldiers’ self-reported work functioning during deployment, suggesting the need to evaluate moderating factors. In the current study, three relationship factors (marital satisfaction, conflictual communication, and proportion of conversation focused on problems) were tested as moderators of communication frequency and negative marriage-to-work spillover for soldiers. Whereas the three relationship factors were independently related to negative spillover, none significantly moderated the relationship between communication frequency and spillover. The overall pattern of results suggests that (a) lower marital satisfaction, a focus on problems during communication, and conflictual communication are each strongly linked to spillover for deployed soldiers, and (b) military couples may be self-restricting deployment communication frequency when experiencing less marital satisfaction and higher rates of negative communication. Implications for communication during deployment are discussed. PMID:26236093
Deployment hinge using wraparound strips
NASA Technical Reports Server (NTRS)
Blanc, Eric
1992-01-01
Aerospatiale developed a new appendage deployment concept called AMEDE (French acronym for improvement of deployment mechanisms) with a view toward increased simplicity and functional reliability. This new concept, applicable to the deployment of any type of spaceborne appendage (in particular to solar arrays), enables deployment without synchronization or speed regulation devices. On the other hand, it requires the use of hinges with low driving or resistive torques. The AMEDE concept is compared with the conventional deployment concept. The conceptual and functional principles for the ADELE hinge are presented, as well as the hinges' main characteristics. The development status of both the AMEDE concept and the ADELE (French acronym for deployment hinge using wraparound strips) hinge are addressed.
NASA Technical Reports Server (NTRS)
Kolaini, Ali R.; Doty, Benjamin; Chang, Zensheu
2012-01-01
Loudspeakers have been used for acoustic qualification of spacecraft, reflectors, solar panels, and other acoustically responsive structures for more than a decade. Limited measurements from some of the recent speaker tests used to qualify flight hardware have indicated significant spatial variation of the acoustic field within the test volume. Also structural responses have been reported to differ when similar tests were performed using reverberant chambers. To address the impact of non-uniform acoustic field on structural responses, a series of acoustic tests were performed using a flat panel and a 3-ft cylinder exposed to the field controlled by speakers and repeated in a reverberant chamber. The speaker testing was performed using multi-input-single-output (MISO) and multi-input-multi-output (MIMO) control schemes with and without the test articles. In this paper the spatial variation of the acoustic field due to acoustic standing waves and their impacts on the structural responses in RAT and DFAT (both using MISO and MIMO controls for DFAT) are discussed in some detail.
Deng, Z. Daniel; Weiland, Mark A.; Fu, Tao; Seim, Tom A.; LaMarche, Brian L.; Choi, Eric Y.; Carlson, Thomas J.; Eppard, M. Brad
2011-01-01
In Part 1 of this paper, we presented the engineering design and instrumentation of the Juvenile Salmon Acoustic Telemetry System (JSATS) cabled system, a nonproprietary sensing technology developed by the U.S. Army Corps of Engineers, Portland District (Oregon, USA) to meet the needs for monitoring the survival of juvenile salmonids through the hydroelectric facilities within the Federal Columbia River Power System. Here in Part 2, we describe how the JSATS cabled system was employed as a reference sensor network for detecting and tracking juvenile salmon. Time-of-arrival data for valid detections on four hydrophones were used to solve for the three-dimensional (3D) position of fish surgically implanted with JSATS acoustic transmitters. Validation tests demonstrated high accuracy of 3D tracking up to 100 m upstream from the John Day Dam spillway. The along-dam component, used for assigning the route of fish passage, had the highest accuracy; the median errors ranged from 0.02 to 0.22 m, and root mean square errors ranged from 0.07 to 0.56 m at distances up to 100 m. For the 2008 case study at John Day Dam, the range for 3D tracking was more than 100 m upstream of the dam face where hydrophones were deployed, and detection and tracking probabilities of fish tagged with JSATS acoustic transmitters were higher than 98%. JSATS cabled systems have been successfully deployed on several major dams to acquire information for salmon protection and for development of more “fish-friendly” hydroelectric facilities. PMID:22163919
DOE Office of Scientific and Technical Information (OSTI.GOV)
Deng, Zhiqun; Weiland, Mark A.; Fu, Tao
2011-05-26
In Part 1 of this paper [1], we presented the engineering design and instrumentation of the Juvenile Salmon Acoustic Telemetry System (JSATS) cabled system, a nonproprietary technology developed by the U.S. Army Corps of Engineers, Portland District, to meet the needs for monitoring the survival of juvenile salmonids through the 31 dams in the Federal Columbia River Power System. Here in Part 2, we describe how the JSATS cabled system was employed as a reference sensor network for detecting and tracking juvenile salmon. Time-of-arrival data for valid detections on four hydrophones were used to solve for the three-dimensional (3D) positionmore » of fish surgically implanted with JSATS acoustic transmitters. Validation tests demonstrated high accuracy of 3D tracking up to 100 m from the John Day Dam spillway. The along-dam component, used for assigning the route of fish passage, had the highest accuracy; the median errors ranged from 0.06 to 0.22 m, and root mean square errors ranged from 0.05 to 0.56 m at distances up to 100 m. For the case study at John Day Dam during 2008, the range for 3D tracking was more than 100 m upstream of the dam face where hydrophones were deployed, and detection and tracking probabilities of fish tagged with JSATS acoustic transmitters were higher than 98%. JSATS cabled systems have been successfully deployed on several major dams to acquire information for salmon protection and for development of more “fish-friendly” hydroelectric facilities.« less
Cetacean population density estimation from single fixed sensors using passive acoustics.
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. © 2011 Acoustical Society of America
Vanhille, Christian; Campos-Pozuelo, Cleofé
2014-01-01
The benefits derived from the development of acoustic transistors which act as switches or amplifiers have been reported in the literature. Here we propose a model of acoustic switch. We theoretically demonstrate that the device works: the input signal is totally restored at the output when the switch is on whereas the output signal nulls when the switch is off. The switch, on or off, depends on a secondary acoustic field capable to manipulate the main acoustic field. The model relies on the attenuation effect of many oscillating bubbles on the main travelling wave in the liquid, as well as on the capacity of the secondary acoustic wave to move the bubbles. This model evidences the concept of acoustic switch (transistor) with 100% efficiency. Copyright © 2013 Elsevier B.V. All rights reserved.
DOT National Transportation Integrated Search
2014-05-01
This document is a summary of all responses the USDOT received from the Connected Vehicle Pilot Deployment Programs Request for Information (RFI) Notice put out by the Federal Highway Administration on 03/12/2014.
Acoustic tweezers via sub-time-of-flight regime surface acoustic waves.
Collins, David J; Devendran, Citsabehsan; Ma, Zhichao; Ng, Jia Wei; Neild, Adrian; Ai, Ye
2016-07-01
Micrometer-scale acoustic waves are highly useful for refined optomechanical and acoustofluidic manipulation, where these fields are spatially localized along the transducer aperture but not along the acoustic propagation direction. In the case of acoustic tweezers, such a conventional acoustic standing wave results in particle and cell patterning across the entire width of a microfluidic channel, preventing selective trapping. We demonstrate the use of nanosecond-scale pulsed surface acoustic waves (SAWs) with a pulse period that is less than the time of flight between opposing transducers to generate localized time-averaged patterning regions while using conventional electrode structures. These nodal positions can be readily and arbitrarily positioned in two dimensions and within the patterning region itself through the imposition of pulse delays, frequency modulation, and phase shifts. This straightforward concept adds new spatial dimensions to which acoustic fields can be localized in SAW applications in a manner analogous to optical tweezers, including spatially selective acoustic tweezers and optical waveguides.
RAEGE Project Update: Yebes Observatory Broadband Receiver Ready for VGOS
NASA Astrophysics Data System (ADS)
IGN Yebes Observatory staff
2016-12-01
An update of the deployment and activities at the Spanish/Portuguese RAEGE project (``Atlantic Network of Geodynamical and Space Stations'') is presented. While regular observations with the Yebes radio telescope are on-going, technological developments about receivers for VGOS are progressing at the Yebes laboratories.
SAW correlator spread spectrum receiver
Brocato, Robert W
2014-04-01
A surface acoustic wave (SAW) correlator spread-spectrum (SS) receiver is disclosed which utilizes a first demodulation stage with a chip length n and a second demodulation stage with a chip length m to decode a transmitted SS signal having a code length l=n.times.m which can be very long (e.g. up to 2000 chips or more). The first demodulation stage utilizes a pair of SAW correlators which demodulate the SS signal to generate an appropriate code sequence at an intermediate frequency which can then be fed into the second demodulation stage which can be formed from another SAW correlator, or by a digital correlator. A compound SAW correlator comprising two input transducers and a single output transducer is also disclosed which can be used to form the SAW correlator SS receiver, or for use in processing long code length signals.
2006-08-11
thermo luminescent dosimeter ( TLD badge)) are required for performing specific tasks in a safe manner while deployed, personnel must be trained on the...monitoring devices (e.g., thermo luminescent dosimeter ( TLD badge)) as required by occupational specialty of personnel. (E4.A1.1.5.) 5.5.8 X X...assigned, attached, on temporary duty, or temporary additional duty to deployed units. Report the data electronically to the DMDC (at the SECRET level
High frequency acoustic propagation under variable sea surfaces
NASA Astrophysics Data System (ADS)
Senne, Joseph
This dissertation examines the effects of rough sea surfaces and sub-surface bubbles on high frequency acoustic transmissions. Owing to the strong attenuation of electromagnetic waves in seawater, acoustic waves are used in the underwater realm much in the same way that electromagnetic waves are used in the atmosphere. The transmission and reception of acoustic waves in the underwater environment is important for a variety of fields including navigation, ocean observation, and real-time communications. Rough sea surfaces and sub-surface bubbles alter the acoustic signals that are received not only in the near-surface water column, but also at depth. This dissertation demonstrates that surface roughness and sub-surface bubbles notably affect acoustic transmissions with frequency ranges typical of underwater communications systems (10-50 kHz). The influence of rough surfaces on acoustic transmissions is determined by modeling forward propagation subject to sea surface dynamics that vary with time scales of less than a second to tens of seconds. A time-evolving rough sea surface model is combined with a rough surface formulation of a parabolic equation model for predicting time-varying acoustic fields. Linear surface waves are generated from surface wave spectra, and evolved in time using a Runge-Kutta integration technique. This evolving, range-dependent surface information is combined with other environmental parameters and fed into the acoustic model, giving an approximation of the time-varying acoustic field. The wide-angle parabolic equation model manages the rough sea surfaces by molding them into the boundary conditions for calculations of the near-surface acoustic field. The influence of sub-surface bubbles on acoustic transmissions is determined by modeling the population of bubbles near the surface and using those populations to approximate the effective changes in sound speed and attenuation. Both range-dependent and range-independent bubble models are
Propulsive Small Expendable Deployer System (ProSEDS)
NASA Technical Reports Server (NTRS)
Ballance, Judy; Johnson, Les; Rogacki, John R. (Technical Monitor)
2000-01-01
The Propulsive Small Expendable Deployer System (ProSEDS) space experiment will demonstrate the use of an electrodynamic tether propulsion system to generate thrust in space by decreasing the orbital altitude of a Delta II Expendable Launch Vehicle (ELV) second stage. ProSEDS, which is planned to fly in 2001, will use the flight proven Small Expendable Deployer System (SEDS) to deploy a tether (5km bare wire plus 10 km spectra or dyneema) from a Delta II second stage to achieve approximately 0.4N drag thrust. ProSEDS will utilize the tether-generated current to provide limited spacecraft power. The ProSEDs instrumentation includes a Langmuir probe and Differential Ion Flux Probe, which will determine the characteristics of the ambient ionospheric plasma. Two Global Positioning System (GPS) receivers will be used (one on the Delta and one on the endmass) to help determine tether dynamics and to limit transmitter operations to occasions when the spacecraft is over selected ground stations, The flight experiment is a precursor to the more ambitious electrodynamic tether upper stage demonstration mission, which will be capable of orbit raising, lowering and inclination changes-all using electrodynamic thrust. An immediate application of ProSEDS technology is for the deorbit of spent satellites for orbital debris mitigation. In addition to the use of this technology to provide orbit transfer and debris mitigation it may also be an attractive option for future missions to Jupiter and any other planetary body with a magnetosphere.
Acoustic levitation of an object larger than the acoustic wavelength.
Andrade, Marco A B; Okina, Fábio T A; Bernassau, Anne L; Adamowski, Julio C
2017-06-01
Levitation and manipulation of objects by sound waves have a wide range of applications in chemistry, biology, material sciences, and engineering. However, the current acoustic levitation techniques are mainly restricted to particles that are much smaller than the acoustic wavelength. In this work, it is shown that acoustic standing waves can be employed to stably levitate an object much larger than the acoustic wavelength in air. The levitation of a large slightly curved object weighting 2.3 g is demonstrated by using a device formed by two 25 kHz ultrasonic Langevin transducers connected to an aluminum plate. The sound wave emitted by the device provides a vertical acoustic radiation force to counteract gravity and a lateral restoring force that ensure horizontal stability to the levitated object. In order to understand the levitation stability, a numerical model based on the finite element method is used to determine the acoustic radiation force that acts on the object.
ACOUSTICS IN ARCHITECTURAL DESIGN, AN ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS.
ERIC Educational Resources Information Center
DOELLE, LESLIE L.
THE PURPOSE OF THIS ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS WAS--(1) TO COMPILE A CLASSIFIED BIBLIOGRAPHY, INCLUDING MOST OF THOSE PUBLICATIONS ON ARCHITECTURAL ACOUSTICS, PUBLISHED IN ENGLISH, FRENCH, AND GERMAN WHICH CAN SUPPLY A USEFUL AND UP-TO-DATE SOURCE OF INFORMATION FOR THOSE ENCOUNTERING ANY ARCHITECTURAL-ACOUSTIC DESIGN…
Comparison between diffuse infrared and acoustic transmission over the human skull.
Wang, Q; Reganti, N; Yoshioka, Y; Howell, M; Clement, G T
2015-01-01
Skull-induced distortion and attenuation present a challenge to both transcranial imaging and therapy. Whereas therapeutic procedures have been successful in offsetting aberration using from prior CTs, this approach impractical for imaging. In effort to provide a simplified means for aberration correction, we have been investigating the use of diffuse infrared light as an indicator of acoustic properties. Infrared wavelengths were specifically selected for tissue penetration; however this preliminary study was performed through bone alone via a transmission mode to facilitate comparison with acoustic measurements. The inner surface of a half human skull, cut along the sagittal midline, was illuminated using an infrared heat lamp and images of the outer surface were acquired with an IR-sensitive camera. A range of source angles were acquired and averaged to eliminate source bias. Acoustic measurement were likewise obtained over the surface with a source (1MHz, 12.7mm-diam) oriented parallel to the skull surface and hydrophone receiver (1mm PVDF). Preliminary results reveal a positive correlation between sound speed and optical intensity, whereas poor correlation is observed between acoustic amplitude and optical intensity.
Won, Tae-Hee; Park, Sung-Joon
2012-01-01
For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication.
Three small deployed satellites
2012-10-04
ISS033-E-009282 (4 Oct. 2012) --- Several tiny satellites are featured in this image photographed by an Expedition 33 crew member on the International Space Station. The satellites were released outside the Kibo laboratory using a Small Satellite Orbital Deployer attached to the Japanese module’s robotic arm on Oct. 4, 2012. Japan Aerospace Exploration Agency astronaut Aki Hoshide, flight engineer, set up the satellite deployment gear inside the lab and placed it in the Kibo airlock. The Japanese robotic arm then grappled the deployment system and its satellites from the airlock for deployment. Earth’s horizon and the blackness of space provide the backdrop for the scene.
NASA Technical Reports Server (NTRS)
Houston, Janice; Counter, D.; Giacomoni, D.
2015-01-01
The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible pre-launch test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments and to determine the acoustic reduction with an above deck water sound suppression system. The SMAT was conducted at Marshall Space Flight Center and the test article included a 5% scale SLS vehicle model, tower and Mobile Launcher. Acoustic and pressure data were measured by approximately 250 instruments. The SMAT liftoff acoustic results are presented, findings are discussed and a comparison is shown to the Ares I Scale Model Acoustic Test (ASMAT) results.
Moore, Tyler M; Risbrough, Victoria B; Baker, Dewleen G; Larson, Gerald E; Glenn, Daniel E; Nievergelt, Caroline M; Maihofer, Adam; Port, Allison M; Jackson, Chad T; Ruparel, Kosha; Gur, Ruben C
2017-12-01
The Marine Resiliency Study-II examined changes in symptomatology across a deployment cycle to Afghanistan. U.S. Servicemembers (N = 1041) received clinical testing at two time points either bracketing a deployment (855) or not (186). Factor analyses were used to generate summary and change scores from Time 1 to Time 2. A between-subject design was used to examine changes across the deployment cycle with deployment (low-trauma, high-trauma, and non-deployed) and social support (low vs. high) as the grouping variables. Insomnia increased post-deployment regardless of deployment trauma (std. effect for high-trauma and low-trauma = 0.39 and 0.26, respectively). Only the high-trauma group showed increased PTSD symptoms and non-perspective-taking (std. effect = 0.40 and 0.30, respectively), while low-trauma showed decreased anxiety symptoms after deployment (std. effect = -0.17). These associations also depend on social support, with std. effects ranging from -0.22 to 0.51. When the groups were compared, the high-trauma deployed group showed significantly worse PTSD and non-perspective-taking than all other groups. Similar to studies in other military divisions, increased clinical symptoms were associated with high deployment stress in active duty Servicemembers, and social support shows promise as a moderator of said association. Copyright © 2017 Elsevier Ltd. All rights reserved.
... Cerebellopontine angle tumor; Angle tumor; Hearing loss - acoustic; Tinnitus - acoustic ... that makes it hard to hear conversations Ringing ( tinnitus ) in the affected ear Less common symptoms include: ...
Marandet, Christian; Roux, Philippe; Nicolas, Barbara; Mars, Jérôme
2011-01-01
This study demonstrates experimentally at the laboratory scale the detection and localization of a wavelength-sized target in a shallow ultrasonic waveguide between two source-receiver arrays at 3 MHz. In the framework of the acoustic barrier problem, at the 1/1000 scale, the waveguide represents a 1.1-km-long, 52-m-deep ocean acoustic channel in the kilohertz frequency range. The two coplanar arrays record in the time-domain the transfer matrix of the waveguide between each pair of source-receiver transducers. Invoking the reciprocity principle, a time-domain double-beamforming algorithm is simultaneously performed on the source and receiver arrays. This array processing projects the multireverberated acoustic echoes into an equivalent set of eigenrays, which are defined by their launch and arrival angles. Comparison is made between the intensity of each eigenray without and with a target for detection in the waveguide. Localization is performed through tomography inversion of the acoustic impedance of the target, using all of the eigenrays extracted from double beamforming. The use of the diffraction-based sensitivity kernel for each eigenray provides both the localization and the signature of the target. Experimental results are shown in the presence of surface waves, and methodological issues are discussed for detection and localization.
EnEx-RANGE - Robust autonomous Acoustic Navigation in Glacial icE
NASA Astrophysics Data System (ADS)
Heinen, Dirk; Eliseev, Dmitry; Henke, Christoph; Jeschke, Sabina; Linder, Peter; Reuter, Sebastian; Schönitz, Sebastian; Scholz, Franziska; Weinstock, Lars Steffen; Wickmann, Stefan; Wiebusch, Christopher; Zierke, Simon
2017-03-01
Within the Enceladus Explorer Initiative of the DLR Space Administration navigation technologies for a future space mission are in development. Those technologies are the basis for the search for extraterrestrial life on the Saturn moon Enceladus. An autonomous melting probe, the EnEx probe, aims to extract a liquid sample from a water reservoir below the icy crust. A first EnEx probe was developed and demonstrated in a terrestrial scenario at the Bloodfalls, Taylor Glacier, Antarctica in November 2014. To enable navigation in glacier ice two acoustic systems were integrated into the probe in addition to conventional navigation technologies. The first acoustic system determines the position of the probe during the run based on propagation times of acoustic signals from emitters at reference positions at the glacier surface to receivers in the probe. The second system provides information about the forefield of the probe. It is based on sonographic principles with phased array technology integrated in the probe's melting head. Information about obstacles or sampling regions in the probe's forefield can be acquired. The development of both systems is now continued in the project EnEx-RANGE. The emitters of the localization system are replaced by a network of intelligent acoustic enabled melting probes. These localize each other by means of acoustic signals and create the reference system for the EnEx probe. This presentation includes the discussion of the intelligent acoustic network, the acoustic navigation systems of the EnEx probe and results of terrestrial tests.
Double negative acoustic metastructure for attenuation of acoustic emissions
NASA Astrophysics Data System (ADS)
Kumar, Sanjay; Bhushan, Pulak; Prakash, Om; Bhattacharya, Shantanu
2018-03-01
Acoustic metamaterials hold great potential for attenuation of low frequency acoustic emissions. However, a fundamental challenge is achieving high transmission loss over a broad frequency range. In this work, we report a double negative acoustic metastructure for absorption of low frequency acoustic emissions in an aircraft. This is achieved by utilizing a periodic array of hexagonal cells interconnected with a neck and mounted with an elastic membrane on both ends. An average transmission loss of 56 dB under 500 Hz and an overall absorption of over 48% have been realized experimentally. The negative mass density is derived from the dipolar resonances created as a result of the in-phase movement of the membranes. Further, the negative bulk modulus is ascribed to the combined effect of out-of-phase acceleration of the membranes and the Helmholtz resonator. The proposed metastructure enables absorption of low frequency acoustic emissions with improved functionality that is highly desirable for varied applications.
AURP: An AUV-Aided Underwater Routing Protocol for Underwater Acoustic Sensor Networks
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
AURP: an AUV-aided underwater routing protocol for underwater acoustic sensor networks.
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.
Reducing the dimensions of acoustic devices using anti-acoustic-null media
NASA Astrophysics Data System (ADS)
Li, Borui; Sun, Fei; He, Sailing
2018-02-01
An anti-acoustic-null medium (anti-ANM), a special homogeneous medium with anisotropic mass density, is designed by transformation acoustics (TA). Anti-ANM can greatly compress acoustic space along the direction of its main axis, where the size compression ratio is extremely large. This special feature can be utilized to reduce the geometric dimensions of classic acoustic devices. For example, the height of a parabolic acoustic reflector can be greatly reduced. We also design a brass-air structure on the basis of the effective medium theory to materialize the anti-ANM in a broadband frequency range. Numerical simulations verify the performance of the proposed anti-ANM.
North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea
2016-06-21
the "Special Issue on Deep-water Ocean Acoustics" in the Journal of the Acoustical Society of America (Vol. 134, No . 4, Pt. 2 of 2 , October20 13...also listed. Fourteen (14) of these publications appeared in the " Special Issue on Deep-water Ocean Acoustics" in the Journal of the Acoustical
NASA Astrophysics Data System (ADS)
Kang, Jian
2004-05-01
Much attention has been paid to acoustic spaces such as concert halls and recording studios, whereas research on nonacoustic buildings/spaces has been rather limited, especially from the viewpoint of acoustic comfort. In this research a series of case studies has been carried out on this topic, considering various spaces including shopping mall atrium spaces, library reading rooms, football stadia, swimming spaces, churches, dining spaces, as well as urban open public spaces. The studies focus on the relationships between objective acoustic indices such as sound pressure level and reverberation time and perceptions of acoustic comfort. The results show that the acoustic atmosphere is an important consideration in such spaces and the evaluation of acoustic comfort may vary considerably even if the objective acoustic indices are the same. It is suggested that current guidelines and technical regulations are insufficient in terms of acoustic design of these spaces, and the relationships established from the case studies between objective and subjective aspects would be useful for developing further design guidelines. [Work supported partly by the British Academy.
Evaluation of micro-GPS receivers for tracking small-bodied mammals
Shipley, Lisa A.; Forbey, Jennifer S.; Olsoy, Peter J.
2017-01-01
GPS telemetry markedly enhances the temporal and spatial resolution of animal location data, and recent advances in micro-GPS receivers permit their deployment on small mammals. One such technological advance, snapshot technology, allows for improved battery life by reducing the time to first fix via postponing recovery of satellite ephemeris (satellite location) data and processing of locations. However, no previous work has employed snapshot technology for small, terrestrial mammals. We evaluated performance of two types of micro-GPS (< 20 g) receivers (traditional and snapshot) on a small, semi-fossorial lagomorph, the pygmy rabbit (Brachylagus idahoensis), to understand how GPS errors might influence fine-scale assessments of space use and habitat selection. During stationary tests, microtopography (i.e., burrows) and satellite geometry had the largest influence on GPS fix success rate (FSR) and location error (LE). There was no difference between FSR while animals wore the GPS collars above ground (determined via light sensors) and FSR generated during stationary, above-ground trials, suggesting that animal behavior other than burrowing did not markedly influence micro-GPS errors. In our study, traditional micro-GPS receivers demonstrated similar FSR and LE to snapshot receivers, however, snapshot receivers operated inconsistently due to battery and software failures. In contrast, the initial traditional receivers deployed on animals experienced some breakages, but a modified collar design consistently functioned as expected. If such problems were resolved, snapshot technology could reduce the tradeoff between fix interval and battery life that occurs with traditional micro-GPS receivers. Our results suggest that micro-GPS receivers are capable of addressing questions about space use and resource selection by small mammals, but that additional techniques might be needed to identify use of habitat structures (e.g., burrows, tree cavities, rock crevices) that
Stanistreet, Joy E; Risch, Denise; Van Parijs, Sofie M
2013-01-01
Passive acoustic tracking provides an unobtrusive method of studying the movement of sound-producing animals in the marine environment where traditional tracking methods may be costly or infeasible. We used passive acoustic tracking to characterize the fine-scale movements of singing humpback whales (Megaptera novaeangliae) on a northwest Atlantic feeding ground. Male humpback whales produce complex songs, a phenomenon that is well documented in tropical regions during the winter breeding season, but also occurs at higher latitudes during other times of year. Acoustic recordings were made throughout 2009 using an array of autonomous recording units deployed in the Stellwagen Bank National Marine Sanctuary. Song was recorded during spring and fall, and individual singing whales were localized and tracked throughout the array using a correlation sum estimation method on the time-synchronized recordings. Tracks were constructed for forty-three song sessions, revealing a high level of variation in movement patterns in both the spring and fall seasons, ranging from slow meandering to faster directional movement. Tracks were 30 min to 8 h in duration, and singers traveled distances ranging from 0.9 to 20.1 km. Mean swimming speed was 2.06 km/h (SD 0.95). Patterns and rates of movement indicated that most singers were actively swimming. In one case, two singers were tracked simultaneously, revealing a potential acoustic interaction. Our results provide a first description of the movements of singers on a northwest Atlantic feeding ground, and demonstrate the utility of passive acoustic tracking for studying the fine-scale movements of cetaceans within the behavioral context of their calls. These methods have further applications for conservation and management purposes, particularly by enhancing our ability to estimate cetacean densities using passive acoustic monitoring.
Stanistreet, Joy E.; Risch, Denise; Van Parijs, Sofie M.
2013-01-01
Passive acoustic tracking provides an unobtrusive method of studying the movement of sound-producing animals in the marine environment where traditional tracking methods may be costly or infeasible. We used passive acoustic tracking to characterize the fine-scale movements of singing humpback whales (Megaptera novaeangliae) on a northwest Atlantic feeding ground. Male humpback whales produce complex songs, a phenomenon that is well documented in tropical regions during the winter breeding season, but also occurs at higher latitudes during other times of year. Acoustic recordings were made throughout 2009 using an array of autonomous recording units deployed in the Stellwagen Bank National Marine Sanctuary. Song was recorded during spring and fall, and individual singing whales were localized and tracked throughout the array using a correlation sum estimation method on the time-synchronized recordings. Tracks were constructed for forty-three song sessions, revealing a high level of variation in movement patterns in both the spring and fall seasons, ranging from slow meandering to faster directional movement. Tracks were 30 min to 8 h in duration, and singers traveled distances ranging from 0.9 to 20.1 km. Mean swimming speed was 2.06 km/h (SD 0.95). Patterns and rates of movement indicated that most singers were actively swimming. In one case, two singers were tracked simultaneously, revealing a potential acoustic interaction. Our results provide a first description of the movements of singers on a northwest Atlantic feeding ground, and demonstrate the utility of passive acoustic tracking for studying the fine-scale movements of cetaceans within the behavioral context of their calls. These methods have further applications for conservation and management purposes, particularly by enhancing our ability to estimate cetacean densities using passive acoustic monitoring. PMID:23593447
NASA Astrophysics Data System (ADS)
Murgan, I.; Candel, I.; Ioana, C.; Digulescu, A.; Bunea, F.; Ciocan, G. D.; Anghel, A.; Vasile, G.
2016-11-01
In this paper, we present a novel approach to non-intrusive flow velocity profiling technique using multi-element sensor array and wide-band signal's processing methods. Conventional techniques for the measurements of the flow velocity profiles are usually based on intrusive instruments (current meters, acoustic Doppler profilers, Pitot tubes, etc.) that take punctual velocity readings. Although very efficient, these choices are limited in terms of practical cases of applications especially when non-intrusive measurements techniques are required and/or a spatial accuracy of the velocity profiling is required This is due to factors related to hydraulic machinery down time, the often long time duration needed to explore the entire section area, the frequent cumbersome number of devices that needs to be handled simultaneously, or the impossibility to perform intrusive tests. In the case of non-intrusive flow profiling methods based on acoustic techniques, previous methods concentrated on using a large number of acoustic transducers placed around the measured section. Although feasible, this approach presents several major drawbacks such as a complicated signal timing, transmission, acquisition and recording system, resulting in a relative high cost of operation. In addition, because of the geometrical constraints, a desired number of sensors may not be installed. Recent results in acoustic flow metering based on wide band signals and adaptive beamforming proved that it is possible to achieve flow velocity profiles using less acoustic transducers. In a normal acoustic time of flight path the transducers are both emitters and receivers, sequentially changing their roles. In the new configuration, proposed in this paper, two new receivers are added on each side. Since the beam angles of each acoustic transducer are wide enough the newly added transducers can receive the transmitted signals and additional time of flight estimation can be done. Thus, several flow
High-acceleration cable deployment
NASA Technical Reports Server (NTRS)
Barns, C. E.; Canning, T. N.; Gin, B.; King, R. W.; Murphy, J. P.
1980-01-01
Prototype high-acceleration umbilical-cable deployment allows electrical communication between above-ground instrumentation and ballistic projectile below surface. Cable deployment is made up of forebody and afterbody. Foreboy can be separated from afterbody by rocket, or they can be fired as unit at target that stops afterbody on impact (forebody would continue, deploying cable). Similar design could be used in study of sea ice and in other surface-penetration studies.
NASA Astrophysics Data System (ADS)
Wenzel, Elizabeth M.; Fisher, Scott S.; Stone, Philip K.; Foster, Scott H.
1991-03-01
The real time acoustic display capabilities are described which were developed for the Virtual Environment Workstation (VIEW) Project at NASA-Ames. The acoustic display is capable of generating localized acoustic cues in real time over headphones. An auditory symbology, a related collection of representational auditory 'objects' or 'icons', can be designed using ACE (Auditory Cue Editor), which links both discrete and continuously varying acoustic parameters with information or events in the display. During a given display scenario, the symbology can be dynamically coordinated in real time with 3-D visual objects, speech, and gestural displays. The types of displays feasible with the system range from simple warnings and alarms to the acoustic representation of multidimensional data or events.
NASA Technical Reports Server (NTRS)
Wenzel, Elizabeth M.; Fisher, Scott S.; Stone, Philip K.; Foster, Scott H.
1991-01-01
The real time acoustic display capabilities are described which were developed for the Virtual Environment Workstation (VIEW) Project at NASA-Ames. The acoustic display is capable of generating localized acoustic cues in real time over headphones. An auditory symbology, a related collection of representational auditory 'objects' or 'icons', can be designed using ACE (Auditory Cue Editor), which links both discrete and continuously varying acoustic parameters with information or events in the display. During a given display scenario, the symbology can be dynamically coordinated in real time with 3-D visual objects, speech, and gestural displays. The types of displays feasible with the system range from simple warnings and alarms to the acoustic representation of multidimensional data or events.
Simulation of Acoustics for Ares I Scale Model Acoustic Tests
NASA Technical Reports Server (NTRS)
Putnam, Gabriel; Strutzenberg, Louise L.
2011-01-01
The Ares I Scale Model Acoustics Test (ASMAT) is a series of live-fire tests of scaled rocket motors meant to simulate the conditions of the Ares I launch configuration. These tests have provided a well documented set of high fidelity acoustic measurements useful for validation including data taken over a range of test conditions and containing phenomena like Ignition Over-Pressure and water suppression of acoustics. To take advantage of this data, a digital representation of the ASMAT test setup has been constructed and test firings of the motor have been simulated using the Loci/CHEM computational fluid dynamics software. Results from ASMAT simulations with the rocket in both held down and elevated configurations, as well as with and without water suppression have been compared to acoustic data collected from similar live-fire tests. Results of acoustic comparisons have shown good correlation with the amplitude and temporal shape of pressure features and reasonable spectral accuracy up to approximately 1000 Hz. Major plume and acoustic features have been well captured including the plume shock structure, the igniter pulse transient, and the ignition overpressure.
Polusny, Melissa A; Kumpula, Mandy J; Meis, Laura A; Erbes, Christopher R; Arbisi, Paul A; Murdoch, Maureen; Thuras, Paul; Kehle-Forbes, Shannon M; Johnson, Alexandria K
2014-02-01
Although women in the military are exposed to combat and its aftermath, little is known about whether combat as well as pre-deployment risk/protective factors differentially predict post-deployment PTSD symptoms among women compared to men. The current study assesses the influence of combat-related stressors and pre-deployment risk/protective factors on women's risk of developing PTSD symptoms following deployment relative to men's risk. Participants were 801 US National Guard Soldiers (712 men, 89 women) deployed to Iraq or Afghanistan who completed measures of potential risk/protective factors and PTSD symptoms one month before deployment (Time 1) and measures of deployment-related stressors and PTSD symptoms about 2-3 months after returning from deployment (Time 2). Men reported greater exposure to combat situations than women, while women reported greater sexual stressors during deployment than men. Exposure to the aftermath of combat (e.g., witnessing injured/dying people) did not differ by gender. At Time 2, women reported more severe PTSD symptoms and higher rates of probable PTSD than did men. Gender remained a predictor of higher PTSD symptoms after accounting for pre-deployment symptoms, prior interpersonal victimization, and combat related stressors. Gender moderated the association between several risk factors (combat-related stressors, prior interpersonal victimization, lack of unit support and pre-deployment concerns about life/family disruptions) and post-deployment PTSD symptoms. Elevated PTSD symptoms among female service members were not explained simply by gender differences in pre-deployment or deployment-related risk factors. Combat related stressors, prior interpersonal victimization, and pre-deployment concerns about life and family disruptions during deployment were differentially associated with greater post-deployment PTSD symptoms for women than men. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.
Deployable geodesic truss structure
NASA Technical Reports Server (NTRS)
Mikulas, Martin M., Jr. (Inventor); Rhodes, Marvin D. (Inventor); Simonton, J. Wayne (Inventor)
1987-01-01
A deployable geodesic truss structure which can be deployed from a stowed state to an erected state is described. The truss structure includes a series of bays, each bay having sets of battens connected by longitudinal cross members which give the bay its axial and torsional stiffness. The cross members are hinged at their mid point by a joint so that the cross members are foldable for deployment or collapsing. The bays are deployed and stabilized by actuator means connected between the mid point joints of the cross members. Hinged longerons may be provided to also connect the sets of battens and to collapse for stowing with the rest of the truss structure.
Three small deployed satellites
2012-10-04
ISS033-E-009286 (4 Oct. 2012) --- Several tiny satellites are featured in this image photographed by an Expedition 33 crew member on the International Space Station. The satellites were released outside the Kibo laboratory using a Small Satellite Orbital Deployer attached to the Japanese module’s robotic arm on Oct. 4, 2012. Japan Aerospace Exploration Agency astronaut Aki Hoshide, flight engineer, set up the satellite deployment gear inside the lab and placed it in the Kibo airlock. The Japanese robotic arm then grappled the deployment system and its satellites from the airlock for deployment. A portion of the station’s solar array panels and a blue and white part of Earth provide the backdrop for the scene.
Three small deployed satellites
2012-10-04
ISS033-E-009285 (4 Oct. 2012) --- Several tiny satellites are featured in this image photographed by an Expedition 33 crew member on the International Space Station. The satellites were released outside the Kibo laboratory using a Small Satellite Orbital Deployer attached to the Japanese module’s robotic arm on Oct. 4, 2012. Japan Aerospace Exploration Agency astronaut Aki Hoshide, flight engineer, set up the satellite deployment gear inside the lab and placed it in the Kibo airlock. The Japanese robotic arm then grappled the deployment system and its satellites from the airlock for deployment. A portion of the station’s solar array panels and a blue and white part of Earth provide the backdrop for the scene.
The 30 GHz communications satellite low noise receiver
NASA Technical Reports Server (NTRS)
Steffek, L. J.; Smith, D. W.
1983-01-01
A Ka-band low noise front end in proof of concept (POC) model form for ultimate spaceborne communications receiver deployment was developed. The low noise receiver consists of a 27.5 to 30.0 GHz image enhanced mixer integrated with a 3.7 to 6.2 GHz FET low noise IF amplifier and driven by a self contained 23.8 GHz phase locked local oscillator source. The measured level of receiver performance over the 27.3 to 30.0 GHz RF/3.7 to 6.2 GHz IF band includes 5.5 to 6.5 dB (typ) SSB noise figure, 20.5 + or - 1.5 dB conversion gain and +23 dBm minimum third order two tone intermodulation output intercept point.
Performance Evaluation of a Biometric System Based on Acoustic Images
Izquierdo-Fuente, Alberto; del Val, Lara; Jiménez, María I.; Villacorta, Juan J.
2011-01-01
An acoustic electronic scanning array for acquiring images from a person using a biometric application is developed. Based on pulse-echo techniques, multifrequency acoustic images are obtained for a set of positions of a person (front, front with arms outstretched, back and side). Two Uniform Linear Arrays (ULA) with 15 λ/2-equispaced sensors have been employed, using different spatial apertures in order to reduce sidelobe levels. Working frequencies have been designed on the basis of the main lobe width, the grating lobe levels and the frequency responses of people and sensors. For a case-study with 10 people, the acoustic profiles, formed by all images acquired, are evaluated and compared in a mean square error sense. Finally, system performance, using False Match Rate (FMR)/False Non-Match Rate (FNMR) parameters and the Receiver Operating Characteristic (ROC) curve, is evaluated. On the basis of the obtained results, this system could be used for biometric applications. PMID:22163708
Discriminating silt-and-clay from suspended-sand in rivers using side-looking acoustic profilers
Wright, Scott A.; Topping, David J.; Williams, Cory A.
2010-01-01
techniques rely on measurements of ancillary properties that correlate with suspended-sediment concentration and particle size and thus require the collection of traditional samples for calibration. Through in situ deployments, these methods can provide the high temporal resolution that cannot be achieved through traditional sampling. Here we focus on the evaluation of acoustic profiling techniques (e.g. acoustic-Doppler sideways-looking profilers, or ADPs). One major advantage of acoustic profiling is the ability to concurrently measure water velocity (using Doppler-shift methods) and suspended-sediment concentration such that suspended-sediment flux can be directly computed using data from a single instrument. Acoustic-Doppler profilers have become popular for measuring water velocity and discharge in rivers, through both moving-boat operations and from fixed deployments such as bank-mounted sideways-looking instruments (Hirsch and Costa, 2004, Muste et al., 2007). The method presented herein is most suited to sideways-looking applications as a complement to the "index velocity" technique, whereby an index velocity from a sideways-looking instrument is related to the cross-section average velocity (determined from moving-boat discharge measurements) as a means for developing a continuous water-discharge record (Ruhl and Simpson, 2005). Topping et al. (2007) presented a method for discriminating silt-and-clay from suspended sand, using single frequency ADPs. This method takes advantage of the relations among acoustic backscatter, sediment-induced acoustic attenuation, suspended-sediment concentration (SSC), and particle size distribution (PSD). Backscatter is the amount of sound scattered back and received at the transducer while sediment-induced attenuation is the amount of sound scattered in other directions and absorbed by the sediment particles. Both of these parameters can be measured with an ADP, and their different dependencies on SSC and PSD allow for the
NASA Astrophysics Data System (ADS)
Gallin, L.; Coulouvrat, F.; Farges, T.; Marchiano, R.; Defer, E.; Rison, W.; Schulz, W.; Nuret, M.
2013-12-01
The goal is to study the transformation of the thunder (amplitude, spectrum) during its travel from the lightning channel towards a detector (microphone, microbarometer), considering propagation distances of less than 50 km and complex local meteorological properties. Inside the European HyMeX project, the SOP1 campaign (2012) took place from September 2012 to November 2012 in South of France. An acoustic station (center: 4.39° E, 44.08° N) composed of a microphone array placed inside a microbarometer array was installed by CEA near city of Uzès. It was located in the center of an LMA network coming with two slow antennas. This network was deployed in France for the first time by the New Mexico Tech and LERMA laboratory. The detections from the European lightning location system EUCLID complete this dataset. During the SOP1 period several storms passed over the station. The post-processings of the records point out days with interesting thunderstorms. Especially during the 26th of October 2012 in the evening (around 8 pm) a thunderstorm passed just over the acoustic station. Not too many lightning strokes are detected by EUCLID, the corresponding flashes are then well characterized by the LMA network. Slow antennas present good electric field measurements. The acoustic records have excellent quality. We present for some selected flashes a comparative study of the different measurements (LMA, slow antenna, EUCLID, microphones, microbarometers): focusing on amplitude and spectrum of the thunder waveforms, and on propagation effects due to the meteorological conditions. To quantify the impact of these meteorological conditions on the propagating thunder (from the lightning sources to the acoustic array), a code named Flhoward is used [Dagrau et al., J. Acoust. Soc. Am., 130, 20-32, 2011][Coulouvrat, Wave Motion, 49, 50--63, 2012]. It is designed to simulate the nonlinear propagation of acoustic shock waves through a realistic atmosphere model (including temperature
Ferguson, B G; Lo, K W
2000-10-01
Flight parameter estimation methods for an airborne acoustic source can be divided into two categories, depending on whether the narrow-band lines or the broadband component of the received signal spectrum is processed to estimate the flight parameters. This paper provides a common framework for the formulation and test of two flight parameter estimation methods: one narrow band, the other broadband. The performances of the two methods are evaluated by applying them to the same acoustic data set, which is recorded by a planar array of passive acoustic sensors during multiple transits of a turboprop fixed-wing aircraft and two types of rotary-wing aircraft. The narrow-band method, which is based on a kinematic model that assumes the source travels in a straight line at constant speed and altitude, requires time-frequency analysis of the acoustic signal received by a single sensor during each aircraft transit. The broadband method is based on the same kinematic model, but requires observing the temporal variation of the differential time of arrival of the acoustic signal at each pair of sensors that comprises the planar array. Generalized cross correlation of each pair of sensor outputs using a cross-spectral phase transform prefilter provides instantaneous estimates of the differential times of arrival of the signal as the acoustic wavefront traverses the array.
Improving Passive Time Reversal Underwater Acoustic Communications Using Subarray Processing.
He, Chengbing; Jing, Lianyou; Xi, Rui; Li, Qinyuan; Zhang, Qunfei
2017-04-24
Multichannel receivers are usually employed in high-rate underwater acoustic communication to achieve spatial diversity. In the context of multichannel underwater acoustic communications, passive time reversal (TR) combined with a single-channel adaptive decision feedback equalizer (TR-DFE) is a low-complexity solution to achieve both spatial and temporal focusing. In this paper, we present a novel receiver structure to combine passive time reversal with a low-order multichannel adaptive decision feedback equalizer (TR-MC-DFE) to improve the performance of the conventional TR-DFE. First, the proposed method divides the whole received array into several subarrays. Second, we conduct passive time reversal processing in each subarray. Third, the multiple subarray outputs are equalized with a low-order multichannel DFE. We also investigated different channel estimation methods, including least squares (LS), orthogonal matching pursuit (OMP), and improved proportionate normalized least mean squares (IPNLMS). The bit error rate (BER) and output signal-to-noise ratio (SNR) performances of the receiver algorithms are evaluated using simulation and real data collected in a lake experiment. The source-receiver range is 7.4 km, and the data rate with quadrature phase shift keying (QPSK) signal is 8 kbits/s. The uncoded BER of the single input multiple output (SIMO) systems varies between 1 × 10 - 1 and 2 × 10 - 2 for the conventional TR-DFE, and between 1 × 10 - 2 and 1 × 10 - 3 for the proposed TR-MC-DFE when eight hydrophones are utilized. Compared to conventional TR-DFE, the average output SNR of the experimental data is enhanced by 3 dB.
Effects of ocean thermocline variability on noncoherent underwater acoustic communications.
Siderius, Martin; Porter, Michael B; Hursky, Paul; McDonald, Vincent
2007-04-01
The performance of acoustic modems in the ocean is strongly affected by the ocean environment. A storm can drive up the ambient noise levels, eliminate a thermocline by wind mixing, and whip up violent waves and thereby break up the acoustic mirror formed by the ocean surface. The combined effects of these and other processes on modem performance are not well understood. The authors have been conducting experiments to study these environmental effects on various modulation schemes. Here the focus is on the role of the thermocline on a widely used modulation scheme (frequency-shift keying). Using data from a recent experiment conducted in 100-m-deep water off the coast of Kauai, HI, frequency-shift-key modulation performance is shown to be strongly affected by diurnal cycles in the thermocline. There is dramatic variation in performance (measured by bit error rates) between receivers in the surface duct and receivers in the thermocline. To interpret the performance variations in a quantitative way, a precise metric is introduced based on a signal-to-interference-noise ratio that encompasses both the ambient noise and intersymbol interference. Further, it will be shown that differences in the fading statistics for receivers in and out of the thermocline explain the differences in modem performance.
NASA Technical Reports Server (NTRS)
Carroll, Joseph A.; Alexander, Charles M.
1993-01-01
Design concept promises speed, control, and reliability. Scheme for deploying tether provides for fast, free, and snagless payout and fast, dependable braking. Developed for small, expendable tethers in outer space, scheme also useful in laying transoceanic cables, deploying guidance wires to torpedoes and missiles, paying out rescue lines from ship to ship via rockets, deploying antenna wires, releasing communication and power cables to sonobuoys and expendable bathythermographs, and in reeling out lines from fishing rods.
Inhaled beclomethasone dipropionate improves acoustic measures of voice in patients with asthma.
Balter, M S; Adams, S G; Chapman, K R
2001-12-01
Inhaled corticosteroids have the potential to produce upper-airway side effects such as hoarseness. As new compounds and delivery devices are developed and compared, it is difficult to quantify their adverse upper-airway effects. We undertook the following study to test the ability of an acoustic analysis technique to quantify changes in vocal function in steroid-naive patients with asthma who receive inhaled beclomethasone dipropionate (BDP), 1,000 microg/d for 4 months. Patients self-administered one of four regimens of inhaled BDP. Group 1 patients received one 250-microg puff qid via metered-dose inhaler (MDI); group 2 patients received one 250-microg puff qid via MDI with a holding chamber; group 3 patients received two 250-microg puffs bid via MDI; and group 4 patients received two 250-microg puffs bid via MDI with a holding chamber. A smaller cohort of nonsmoking asthmatic patients was managed without steroid intervention for 4 months. At baseline and again at 8 weeks and 16 weeks after the initiation of BDP treatment, patients underwent spirometry and methacholine challenge. At baseline and again at 2, 4, 8, 12, and 16 weeks, patients underwent voice recording for analysis of voice parameters. The recorded vowels were low-pass filtered (10 KHz), digitized (22 KHz), and analyzed by software to obtain two acoustic measures: (1) jitter, the cycle-to-cycle variation in the time period of the voice signal; and (2) shimmer, the cycle-to-cycle variation in voice signal amplitude. We recruited 77 patients for randomization to inhaled steroid therapy and 10 patients who continued to receive only occasional inhaled bronchodilator therapy. In all active treatment groups, FEV(1), FVC, and provocative concentration of methacholine causing a 20% fall in FEV(1) improved significantly after BDP treatment. Mean jitter scores, a measurement of variation in voice pitch, were not significantly influenced by BDP treatment. However, mean shimmer scores, a reflection of
Eun, Yongsoon
2017-01-01
Underwater Acoustic Sensor Network (UASN) comes with intrinsic constraints because it is deployed in the aquatic environment and uses the acoustic signals to communicate. The examples of those constraints are long propagation delay, very limited bandwidth, high energy cost for transmission, very high signal attenuation, costly deployment and battery replacement, and so forth. Therefore, the routing schemes for UASN must take into account those characteristics to achieve energy fairness, avoid energy holes, and improve the network lifetime. The depth based forwarding schemes in literature use node’s depth information to forward data towards the sink. They minimize the data packet duplication by employing the holding time strategy. However, to avoid void holes in the network, they use two hop node proximity information. In this paper, we propose the Energy and Depth variance-based Opportunistic Void avoidance (EDOVE) scheme to gain energy balancing and void avoidance in the network. EDOVE considers not only the depth parameter, but also the normalized residual energy of the one-hop nodes and the normalized depth variance of the second hop neighbors. Hence, it avoids the void regions as well as balances the network energy and increases the network lifetime. The simulation results show that the EDOVE gains more than 15% packet delivery ratio, propagates 50% less copies of data packet, consumes less energy, and has more lifetime than the state of the art forwarding schemes. PMID:28954395
Acoustic wave filter based on periodically poled lithium niobate.
Courjon, Emilie; Bassignot, Florent; Ulliac, Gwenn; Benchabane, Sarah; Ballandras, Sylvain
2012-09-01
Solutions for the development of compact RF passive transducers as an alternative to standard surface or bulk acoustic wave devices are receiving increasing interest. This article presents results on the development of an acoustic band-pass filter based on periodically poled ferroelectric domains in lithium niobate. The fabrication of periodically poled transducers (PPTs) operating in the range of 20 to 650 MHz has been achieved on 3-in (76.2-mm) 500-μm-thick wafers. This kind of transducer is able to excite elliptical as well as longitudinal modes, yielding phase velocities of about 3800 and 6500 ms(-1), respectively. A new type of acoustic band-pass filter is proposed, based on the use of PPTs instead of the SAWs excited by classical interdigital transducers. The design and the fabrication of such a filter are presented, as well as experimental measurements of its electrical response and transfer function. The feasibility of such a PPT-based filter is thereby demonstrated and the limitations of this method are discussed.
Deep seafloor arrivals in long range ocean acoustic propagation.
Stephen, Ralph A; Bolmer, S Thompson; Udovydchenkov, Ilya A; Worcester, Peter F; Dzieciuch, Matthew A; Andrew, Rex K; Mercer, James A; Colosi, John A; Howe, Bruce M
2013-10-01
Ocean bottom seismometer observations at 5000 m depth during the long-range ocean acoustic propagation experiment in the North Pacific in 2004 show robust, coherent, late arrivals that are not readily explained by ocean acoustic propagation models. These "deep seafloor" arrivals are the largest amplitude arrivals on the vertical particle velocity channel for ranges from 500 to 3200 km. The travel times for six (of 16 observed) deep seafloor arrivals correspond to the sea surface reflection of an out-of-plane diffraction from a seamount that protrudes to about 4100 m depth and is about 18 km from the receivers. This out-of-plane bottom-diffracted surface-reflected energy is observed on the deep vertical line array about 35 dB below the peak amplitude arrivals and was previously misinterpreted as in-plane bottom-reflected surface-reflected energy. The structure of these arrivals from 500 to 3200 km range is remarkably robust. The bottom-diffracted surface-reflected mechanism provides a means for acoustic signals and noise from distant sources to appear with significant strength on the deep seafloor.
NASA Astrophysics Data System (ADS)
Wang, Wenqi; Xie, Yangbo; Popa, Bogdan-Ioan; Cummer, Steven A.
2016-11-01
Acoustic metasurfaces provide useful wavefront shaping capabilities, such as beam steering, acoustic focusing, and asymmetric transmission, in a compact structure. Most acoustic metasurfaces described in the literature are transmissive devices and focus their performance on steering sound beam of the fundamental diffractive order. In addition, the range of incident angles studied is usually below the critical incidence predicted by generalized Snell's law of reflection. In this work, we comprehensively analyze the wave interaction with a generic periodic phase-modulating structure in order to predict the behavior of all diffractive orders, especially for cases beyond critical incidence. Under the guidance of the presented analysis, a broadband reflective metasurface is designed based on an expanded library of labyrinthine acoustic metamaterials. Various local and nonlocal wavefront shaping properties are experimentally demonstrated, and enhanced absorption of higher order diffractive waves is experimentally shown for the first time. The proposed methodology provides an accurate approach for predicting practical diffracted wave behaviors and opens a new perspective for the study of acoustic periodic structures. The designed metasurface extends the functionalities of acoustic metasurfaces and paves the way for the design of thin planar reflective structures for broadband acoustic wave manipulation and extraordinary absorption.
Battlefield decision aid for acoustical ground sensors with interface to meteorological data sources
NASA Astrophysics Data System (ADS)
Wilson, D. Keith; Noble, John M.; VanAartsen, Bruce H.; Szeto, Gregory L.
2001-08-01
The performance of acoustical ground sensors depends heavily on the local atmospheric and terrain conditions. This paper describes a prototype physics-based decision aid, called the Acoustic Battlefield Aid (ABFA), for predicting these environ-mental effects. ABFA integrates advanced models for acoustic propagation, atmospheric structure, and array signal process-ing into a convenient graphical user interface. The propagation calculations are performed in the frequency domain on user-definable target spectra. The solution method involves a parabolic approximation to the wave equation combined with a ter-rain diffraction model. Sensor performance is characterized with Cramer-Rao lower bounds (CRLBs). The CRLB calcula-tions include randomization of signal energy and wavefront orientation resulting from atmospheric turbulence. Available performance characterizations include signal-to-noise ratio, probability of detection, direction-finding accuracy for isolated receiving arrays, and location-finding accuracy for networked receiving arrays. A suite of integrated tools allows users to create new target descriptions from standard digitized audio files and to design new sensor array layouts. These tools option-ally interface with the ARL Database/Automatic Target Recognition (ATR) Laboratory, providing access to an extensive library of target signatures. ABFA also includes a Java-based capability for network access of near real-time data from sur-face weather stations or forecasts from the Army's Integrated Meteorological System. As an example, the detection footprint of an acoustical sensor, as it evolves over a 13-hour period, is calculated.
Validation of Essential Acoustic Parameters for Highly Urgent In-Vehicle Collision Warnings.
Lewis, Bridget A; Eisert, Jesse L; Baldwin, Carryl L
2018-03-01
Objective The aim of this study was to validate the importance of key acoustic criteria for use as in-vehicle forward collision warning (FCW) systems. Background Despite recent advances in vehicle safety, automobile crashes remain one of the leading causes of death. As automation allows for more control of noncritical functions by the vehicle, the potential for disengagement and distraction from the driving task also increases. It is, therefore, as important as ever that in-vehicle safety-critical interfaces are intuitive and unambiguous, promoting effective collision avoidance responses upon first exposure even under divided-attention conditions. Method The current study used a driving simulator to assess the effectiveness of two warnings, one that met all essential acoustic parameters, one that met only some essential parameters, and a no-warning control in the context of a lead vehicle-following task in conjunction with a cognitive distractor task and collision event. Results Participants receiving an FCW comprising five essential acoustic components had improved collision avoidance responses relative to a no-warning condition and an FCW missing essential elements on their first exposure. Responses to a consistently good warning (GMU Prime) improved with subsequent exposures, whereas continued exposure to the less optimal FCW (GMU Sub-Prime) resulted in poorer performance even relative to receiving no warning at all. Conclusions This study provides support for previous warning design studies and for the validity of five key acoustic parameters essential for the design of effective in-vehicle FCWs. Application Results from this study have implications for the design of auditory FCWs and in-vehicle display design.
Rutz, Gary L.; Sholtis, Matthew D.; Adams, Noah S.; Beeman, John W.
2014-01-01
Acoustic telemetry equipment was installed at three sites in the Willamette River during October 2012 to test the effectiveness of using the Juvenile Salmon Acoustic Telemetry System to monitor the movements of fish in a high-flow, high-velocity riverine environment. Hydrophones installed on concrete blocks were placed on the bottom of the river, and data cables were run from the hydrophones to shore where they were attached to anchor points. Under relatively low-flow conditions (less than approximately 10,000 cubic feet per second) the monitoring system remained in place and could be used to detect tagged fish as they traveled downstream during their seaward migration. At river discharge over approximately 10,000 cubic feet per second, the hydrophones were damaged and cables were lost because of the large volume of woody debris in the river and the increase in water velocity. Damage at two of the sites was sufficient to prevent data collection. A limited amount of data was collected from the equipment at the third site. Site selection and deployment strategies were re-evaluated, and an alternate deployment methodology was designed for implementation in 2013.
Baker, Laurie L.; Jonsen, Ian D.; Mills Flemming, Joanna E.; Lidgard, Damian C.; Bowen, William D.; Iverson, Sara J.; Webber, Dale M.
2014-01-01
Understanding the nature of inter-specific and conspecific interactions in the ocean is challenging because direct observation is usually impossible. The development of dual transmitter/receivers, Vemco Mobile Transceivers (VMT), and satellite-linked (e.g. GPS) tags provides a unique opportunity to better understand between and within species interactions in space and time. Quantifying the uncertainty associated with detecting a tagged animal, particularly under varying field conditions, is vital for making accurate biological inferences when using VMTs. We evaluated the detection efficiency of VMTs deployed on grey seals, Halichoerus grypus, off Sable Island (NS, Canada) in relation to environmental characteristics and seal behaviour using generalized linear models (GLM) to explore both post-processed detection data and summarized raw VMT data. When considering only post-processed detection data, only about half of expected detections were recorded at best even when two VMT-tagged seals were estimated to be within 50–200 m of one another. At a separation of 400 m, only about 15% of expected detections were recorded. In contrast, when incomplete transmissions from the summarized raw data were also considered, the ratio of complete transmission to complete and incomplete transmissions was about 70% for distances ranging from 50–1000 m, with a minimum of around 40% at 600 m and a maximum of about 85% at 50 m. Distance between seals, wind stress, and depth were the most important predictors of detection efficiency. Access to the raw VMT data allowed us to focus on the physical and environmental factors that limit a transceiver’s ability to resolve a transmitter’s identity. PMID:24892286
Experimentally-Based Ocean Acoustic Propagation and Coherence Studies
2013-09-30
degradation and/or exploitation of available sonic information. OBJECTIVES An objective is to quantify and explain underwater sound fluctuation...focusing did not entirely match the data because of terrain uncertainty. The paper further notes that a rapid drop-off of received sound level from the...covariance functions of complex demodulated signals. The array gain is defined as the signal to noise ratio for coherently added (beam steered) acoustic
Propulsive Small Expendable Deployer System (ProSEDS)
NASA Technical Reports Server (NTRS)
Curtis, Leslie; Johnson, Les; Brown, Norman S. (Technical Monitor)
2002-01-01
The Propulsive Small Expendable Deployer System (ProSEDS) space experiment will demonstrate the use of an electrodynamic tether propulsion system to generate thrust in space by decreasing the orbital altitude of a Delta 11 Expendable Launch Vehicle second stage. ProSEDS, which is planned on an Air Force GPS Satellite replacement mission in June 2002, will use the flight proven Small Expendable Deployer System (SEDS) to deploy a tether (5 km bare wire plus 10 km non-conducting Dyneema) from a Delta 11 second stage to achieve approx. 0.4N drag thrust. ProSEDS will utilize the tether-generated current to provide limited spacecraft power. The ProSEDS instrumentation includes Langmuir probes and Differential Ion Flux Probes, which will determine the characteristics of the ambient ionospheric plasma. Two Global Positioning System (GPS) receivers will be used (one on the Delta and one on the endmass) to help determine tether dynamics and to limit transmitter operations to occasions when the spacecraft is over selected ground stations. The flight experiment is a precursor to the more ambitious electrodynamic tether upper stage demonstration mission, which will be capable of orbit raising, lowering and inclination changes-all using electrodynamic thrust. An immediate application of ProSEDS technology is for the removal of spent satellites for orbital debris mitigation. In addition to the use of this technology to provide orbit transfer and debris mitigation it may also be an attractive option for future missions to Jupiter and any other planetary body with a magnetosphere.
An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...
Sexual Hearing: The influence of sex hormones on acoustic communication in frogs
Arch, Victoria S.; Narins, Peter M.
2009-01-01
The majority of anuran amphibians (frogs and toads) use acoustic communication to mediate sexual behavior and reproduction. Generally, females find and select their mates using acoustic cues provided by males in the form of conspicuous advertisement calls. In these species, vocal signal production and reception are intimately tied to successful reproduction. Research with anurans has demonstrated that acoustic communication is modulated by reproductive hormones, including gonadal steroids and peptide neuromodulators. Most of these studies have focused on the ways in which hormonal systems influence vocal signal production; however, here we will concentrate on a growing body of literature that examines hormonal modulation of call reception. This literature suggests that reproductive hormones contribute to the coordination of reproductive behaviors between signaler and receiver by modulating sensitivity and spectral filtering of the anuran auditory system. It has become evident that the hormonal systems that influence reproductive behaviors are highly conserved among vertebrate taxa, thus studying the endocrine and neuromodulatory bases of acoustic communication in frogs and toads can lead to insights of broader applicability to hormonal modulation of vertebrate sensory physiology and behavior. PMID:19272318
NASA Astrophysics Data System (ADS)
Taddeucci, J.; Del Bello, E.; Scarlato, P.; Ricci, T.; Andronico, D.; Kueppers, U.; Cannata, A.; Sesterhenn, J.; Spina, L.
2015-12-01
Seismic and acoustic surveillance is routinely performed at several persistent activity volcanoes worldwide. However, interpretation of the signals associated with explosive activity is still equivocal, due to both source variability and the intrinsically limited information carried by the waves. Comparison and cross-correlation of the geophysical quantities with other information in general and visual recording in particular is therefore actively sought. At Etna (Italy) in July 2014, short-lived Strombolian explosions ejected bomb- to lapilli-sized, molten pyroclasts at a remarkably repeatable time interval of about two seconds, offering a rare occasion to systematically investigate the seismic and acoustic fields radiated by this common volcanic source. We deployed FAMoUS (FAst, MUltiparametric Setup for the study of explosive activity) at 260 meters from the vents, recording more than 60 explosions in thermal and visible high-speed videos (50 to 500 frames per second) and broadband seismic and acoustic instruments (1 to 10000 Hz for the acoustic and from 0.01 to 30 Hz for the seismic). Analysis of this dataset highlights nonlinear relationships between the exit velocity and mass of ejecta and the amplitude and frequency of the acoustic signals. It also allows comparing different methods to estimate source depth, and to validate existing theory on the coupling of airwaves with ground motion.
NASA Technical Reports Server (NTRS)
Lee, M. C.; Wang, T. G. (Inventor)
1983-01-01
An acoustic levitation system is described, with single acoustic source and a small reflector to stably levitate a small object while the object is processed as by coating or heating it. The system includes a concave acoustic source which has locations on opposite sides of its axis that vibrate towards and away from a focal point to generate a converging acoustic field. A small reflector is located near the focal point, and preferably slightly beyond it, to create an intense acoustic field that stably supports a small object near the reflector. The reflector is located about one-half wavelength from the focal point and is concavely curved to a radius of curvature (L) of about one-half the wavelength, to stably support an object one-quarter wavelength (N) from the reflector.
Holtschlag, David J.; Aichele, Steve A.
2002-01-01
Detroit River is a connecting channel on the Great Lakes waterway that joins Lake St. Clair with Lake Erie. The river forms part of the international boundary between the United States and Canada in southeastern Michigan and southern Ontario. Drifting buoys were deployed on Detroit River to help investigate flow characteristics of four selected reaches as part of a source water assessment study of public water intakes. The drifting buoys contained global positioning system (GPS) receivers to help track their movements following their deployment. In some deployments, buoys were released across a transect at approximately uniform intervals to better understand flow patterns. In other deployments, buoys were released in clusters to investigate turbulent dispersion characteristics. Computer animations of buoy movements, which can be viewed through the Internet, are developed to help visualize the results of the buoy deployments.
2013-11-19
ISS038-E-003874 (19 Nov. 2013) --- Three nanosatellites, known as Cubesats, are deployed from a Small Satellite Orbital Deployer (SSOD) attached to the Kibo laboratory's robotic arm at 7:10 a.m. (EST) on Nov. 19, 2013. Japan Aerospace Exploration Agency astronaut Koichi Wakata, Expedition 38 flight engineer, monitored the satellite deployment while operating the Japanese robotic arm from inside Kibo. The Cubesats were delivered to the International Space Station Aug. 9, aboard Japan's fourth H-II Transfer Vehicle, Kounotori-4.
Acoustic evaluation of wood quality in standing trees. Part I, Acoustic wave behavior
Xiping Wang; Robert J. Ross; Peter Carter
2007-01-01
Acoustic wave velocities in standing trees or live softwood species were measured by the time-of-flight (TOF) method. Tree velocities were compared with acoustic velocities measured in corresponding butt logs through a resonance acoustic method. The experimental data showed a skewed relationship between tree and log acoustic measurements. For most trees tested,...
Allen, R W; Harnsberger, H R; Shelton, C; King, B; Bell, D A; Miller, R; Parkin, J L; Apfelbaum, R I; Parker, D
1996-08-01
To determine whether unenhanced high-resolution T2-weighted fast spin-echo MR imaging provides an acceptable and less expensive alternative to contrast-enhanced conventional T1-weighted spin-echo MR techniques in the diagnosis of acoustic schwannoma. We reviewed in a blinded fashion the records of 25 patients with pathologically documented acoustic schwannoma and of 25 control subjects, all of whom had undergone both enhanced conventional spin-echo MR imaging and unenhanced fast spin-echo MR imaging of the cerebellopontine angle/internal auditory canal region. The patients were imaged with the use of a quadrature head receiver coil for the conventional spin-echo sequences and dual 3-inch phased-array receiver coils for the fast spin-echo sequences. The size of the acoustic schwannomas ranged from 2 to 40 mm in maximum dimension. The mean maximum diameter was 12 mm, and 12 neoplasms were less than 10 mm in diameter. Acoustic schwannoma was correctly diagnosed on 98% of the fast spin-echo images and on 100% of the enhanced conventional spin-echo images. Statistical analysis of the data using the kappa coefficient demonstrated agreement beyond chance between these two imaging techniques for the diagnosis of acoustic schwannoma. There is no statistically significant difference in the sensitivity and specificity of unenhanced high-resolution fast spin-echo imaging and enhance T1-weighted conventional spin-echo imaging in the detection of acoustic schwannoma. We believe that the unenhanced high-resolution fast spin-echo technique provides a cost-effective method for the diagnosis of acoustic schwannoma.
NASA Astrophysics Data System (ADS)
Cho, Y.; Chang, C.-C.; Wang, L. V.; Zou, J.
2016-02-01
This paper reports the development of a new 16-channel parallel acoustic delay line (PADL) array for real-time photoacoustic tomography (PAT). The PADLs were directly fabricated from single-crystalline silicon substrates using deep reactive ion etching. Compared with other acoustic delay lines (e.g., optical fibers), the micromachined silicon PADLs offer higher acoustic transmission efficiency, smaller form factor, easier assembly, and mass production capability. To demonstrate its real-time photoacoustic imaging capability, the silicon PADL array was interfaced with one single-element ultrasonic transducer followed by one channel of data acquisition electronics to receive 16 channels of photoacoustic signals simultaneously. A PAT image of an optically-absorbing target embedded in an optically-scattering phantom was reconstructed, which matched well with the actual size of the imaged target. Because the silicon PADL array allows a signal-to-channel reduction ratio of 16:1, it could significantly simplify the design and construction of ultrasonic receivers for real-time PAT.
Method and apparatus for detecting internal structures of bulk objects using acoustic imaging
Deason, Vance A.; Telschow, Kenneth L.
2002-01-01
Apparatus for producing an acoustic image of an object according to the present invention may comprise an excitation source for vibrating the object to produce at least one acoustic wave therein. The acoustic wave results in the formation of at least one surface displacement on the surface of the object. A light source produces an optical object wavefront and an optical reference wavefront and directs the optical object wavefront toward the surface of the object to produce a modulated optical object wavefront. A modulator operatively associated with the optical reference wavefront modulates the optical reference wavefront in synchronization with the acoustic wave to produce a modulated optical reference wavefront. A sensing medium positioned to receive the modulated optical object wavefront and the modulated optical reference wavefront combines the modulated optical object and reference wavefronts to produce an image related to the surface displacement on the surface of the object. A detector detects the image related to the surface displacement produced by the sensing medium. A processing system operatively associated with the detector constructs an acoustic image of interior features of the object based on the phase and amplitude of the surface displacement on the surface of the object.
NASA Astrophysics Data System (ADS)
Kuttruff, Heinrich; Mommertz, Eckard
The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.
Deployable reflector structure
NASA Technical Reports Server (NTRS)
Mikulas, Martin, Jr. (Inventor); Hoberman, Charles (Inventor)
1993-01-01
A deployable reflector structure is presented. The structure has a number of movable reflector panels pivotably supported on rigid arms. Several such arms are pivotably connected to a central structure. The arm can move in starburst fashion from a packaged stage, where all arms are vertical, to a deployed stage, where all arms are horizontal. All of the movable reflector panels are maintained at a predetermined angle to an axis of the reflector structure when the arms are pivoted. The reflector panels are stacked tightly on top of each other in the packaged state of the reflector structure. Simple mechanisms are used for avoiding interference between panels on different arms in the packaged stage and for fitting the movable panels together like tiles in the deployed stage.
Acoustic scaling: A re-evaluation of the acoustic model of Manchester Studio 7
NASA Astrophysics Data System (ADS)
Walker, R.
1984-12-01
The reasons for the reconstruction and re-evaluation of the acoustic scale mode of a large music studio are discussed. The design and construction of the model using mechanical and structural considerations rather than purely acoustic absorption criteria is described and the results obtained are given. The results confirm that structural elements within the studio gave rise to unexpected and unwanted low-frequency acoustic absorption. The results also show that at least for the relatively well understood mechanisms of sound energy absorption physical modelling of the structural and internal components gives an acoustically accurate scale model, within the usual tolerances of acoustic design. The poor reliability of measurements of acoustic absorption coefficients, is well illustrated. The conclusion is reached that such acoustic scale modelling is a valid and, for large scale projects, financially justifiable technique for predicting fundamental acoustic effects. It is not appropriate for the prediction of fine details because such small details are unlikely to be reproduced exactly at a different size without extensive measurements of the material's performance at both scales.
JEMRMS Small Satellite Deployment Observation
2012-10-04
ISS033-E-009334 (4 Oct. 2012) --- Several tiny satellites are featured in this image photographed by an Expedition 33 crew member on the International Space Station. The satellites were released outside the Kibo laboratory using a Small Satellite Orbital Deployer attached to the Japanese module’s robotic arm on Oct. 4, 2012. Japan Aerospace Exploration Agency astronaut Aki Hoshide, flight engineer, set up the satellite deployment gear inside the lab and placed it in the Kibo airlock. The Japanese robotic arm then grappled the deployment system and its satellites from the airlock for deployment.
JEMRMS Small Satellite Deployment Observation
2012-10-04
ISS033-E-009458 (4 Oct. 2012) --- Several tiny satellites are featured in this image photographed by an Expedition 33 crew member on the International Space Station. The satellites were released outside the Kibo laboratory using a Small Satellite Orbital Deployer attached to the Japanese module’s robotic arm on Oct. 4, 2012. Japan Aerospace Exploration Agency astronaut Aki Hoshide, flight engineer, set up the satellite deployment gear inside the lab and placed it in the Kibo airlock. The Japanese robotic arm then grappled the deployment system and its satellites from the airlock for deployment.
NASA Technical Reports Server (NTRS)
Hughes, William O.; McNelis, Anne M.; McNelis, Mark E.
2014-01-01
The external acoustic liftoff levels predicted for NASA's future heavy lift launch vehicles are expected to be significantly higher than the environment created by today's commercial launch vehicles. This creates a need to develop an improved acoustic attenuation system for future NASA payload fairings. NASA Glenn Research Center initiated an acoustic test series to characterize the acoustic performance of melamine foam, with and without various acoustic enhancements. This testing was denoted as NEMFAT, which stands for NESC Enhanced Melamine Foam Acoustic Test, and is the subject of this paper. Both absorption and transmission loss testing of numerous foam configurations were performed at the Riverbank Acoustical Laboratory in July 2013. The NEMFAT test data provides an initial acoustic characterization and database of melamine foam for NASA. Because of its acoustic performance and lighter mass relative to fiberglass blankets, melamine foam is being strongly considered for use in the acoustic attenuation systems of NASA's future launch vehicles.
Deployment dynamics and control of large-scale flexible solar array system with deployable mast
NASA Astrophysics Data System (ADS)
Li, Hai-Quan; Liu, Xiao-Feng; Guo, Shao-Jing; Cai, Guo-Ping
2016-10-01
In this paper, deployment dynamics and control of large-scale flexible solar array system with deployable mast are investigated. The adopted solar array system is introduced firstly, including system configuration, deployable mast and solar arrays with several mechanisms. Then dynamic equation of the solar array system is established by the Jourdain velocity variation principle and a method for dynamics with topology changes is introduced. In addition, a PD controller with disturbance estimation is designed to eliminate the drift of spacecraft mainbody. Finally the validity of the dynamic model is verified through a comparison with ADAMS software and the deployment process and dynamic behavior of the system are studied in detail. Simulation results indicate that the proposed model is effective to describe the deployment dynamics of the large-scale flexible solar arrays and the proposed controller is practical to eliminate the drift of spacecraft mainbody.
Min, Hosik
2018-03-01
This study is to examine the effect of student veteran status on abusive relationships, namely, emotional, physical, and sexual abuse. In addition, this study divided student veterans into two groups, deployed and un-deployed veterans, to see whether two groups demonstrate different results on abusive relationships. Logistic regression models were employed as a statistical strategy using the 2011-2014 American College Health Association National College Health Assessment II (ACHA-NCHA-II) data. The results found that deployed veterans were more likely to experience physical abuse, while un-deployed veterans were more likely to experience emotional abuse. Student veterans did not show any significant relationship with sexual abuse regardless deployment experience. It would be appropriate to consider the results of this study to address abusive relationships among student veterans, which help them to not only adjust college life but also succeed in careers and have healthy family relationships.
2013-11-19
ISS038-E-003870 (19 Nov. 2013) --- Three nanosatellites, known as Cubesats, are deployed from a Small Satellite Orbital Deployer (SSOD) attached to the Kibo laboratory’s robotic arm at 7:10 a.m. (EST) on Nov. 19, 2013. Japan Aerospace Exploration Agency astronaut Koichi Wakata, Expedition 38 flight engineer, monitored the satellite deployment while operating the Japanese robotic arm from inside Kibo. The Cubesats were delivered to the International Space Station Aug. 9, aboard Japan’s fourth H-II Transfer Vehicle, Kounotori-4.
2013-11-19
ISS038-E-003869 (19 Nov. 2013) --- Three nanosatellites, known as Cubesats, are deployed from a Small Satellite Orbital Deployer (SSOD) attached to the Kibo laboratory’s robotic arm at 7:10 a.m. (EST) on Nov. 19, 2013. Japan Aerospace Exploration Agency astronaut Koichi Wakata, Expedition 38 flight engineer, monitored the satellite deployment while operating the Japanese robotic arm from inside Kibo. The Cubesats were delivered to the International Space Station Aug. 9, aboard Japan’s fourth H-II Transfer Vehicle, Kounotori-4.
2013-11-19
ISS038-E-003871 (19 Nov. 2013) --- Three nanosatellites, known as Cubesats, are deployed from a Small Satellite Orbital Deployer (SSOD) attached to the Kibo laboratory’s robotic arm at 7:10 a.m. (EST) on Nov. 19, 2013. Japan Aerospace Exploration Agency astronaut Koichi Wakata, Expedition 38 flight engineer, monitored the satellite deployment while operating the Japanese robotic arm from inside Kibo. The Cubesats were delivered to the International Space Station Aug. 9, aboard Japan’s fourth H-II Transfer Vehicle, Kounotori-4.
2013-11-19
ISS038-E-003872 (19 Nov. 2013) --- Three nanosatellites, known as Cubesats, are deployed from a Small Satellite Orbital Deployer (SSOD) attached to the Kibo laboratory’s robotic arm at 7:10 a.m. (EST) on Nov. 19, 2013. Japan Aerospace Exploration Agency astronaut Koichi Wakata, Expedition 38 flight engineer, monitored the satellite deployment while operating the Japanese robotic arm from inside Kibo. The Cubesats were delivered to the International Space Station Aug. 9, aboard Japan’s fourth H-II Transfer Vehicle, Kounotori-4.
NASA Technical Reports Server (NTRS)
Cuschieri, J. M.
1992-01-01
The mobility power flow approach that was previously applied in the derivation of expressions for the vibrational power flow between coupled plate substructures forming an L configuration and subjected to mechanical loading is generalized. Using the generalized expressions, both point and distributed mechanical loads on one or both of the plates can be considered. The generalized approach is extended to deal with acoustic excitation of one of the plate substructures. In this case, the forces (acoustic pressures) acting on the structure are dependent on the response of the structure because of the scattered pressure component. The interaction between the plate structure and the acoustic fluid leads to the derivation of a corrected mode shape for the plates' normal surface velocity and also for the structure mobility functions. The determination of the scattered pressure components in the expressions for the power flow represents an additional component in the power flow balance for the source plate and the receiver plate. This component represents the radiated acoustical power from the plate structure. For a number of coupled plate substrates, the acoustic pressure generated by one substructure will interact with the motion of another substructure. That is, in the case of the L-shaped plate, acoustic interaction exists between the two plate substructures due to the generation of the acoustic waves by each of the substructures. An approach to deal with this phenomena is described.
Energy Harvesting Hybrid Acoustic-Optical Underwater Wireless Sensor Networks Localization.
Saeed, Nasir; Celik, Abdulkadir; Al-Naffouri, Tareq Y; Alouini, Mohamed-Slim
2017-12-26
Underwater wireless technologies demand to transmit at higher data rate for ocean exploration. Currently, large coverage is achieved by acoustic sensor networks with low data rate, high cost, high latency, high power consumption, and negative impact on marine mammals. Meanwhile, optical communication for underwater networks has the advantage of the higher data rate albeit for limited communication distances. Moreover, energy consumption is another major problem for underwater sensor networks, due to limited battery power and difficulty in replacing or recharging the battery of a sensor node. The ultimate solution to this problem is to add energy harvesting capability to the acoustic-optical sensor nodes. Localization of underwater sensor networks is of utmost importance because the data collected from underwater sensor nodes is useful only if the location of the nodes is known. Therefore, a novel localization technique for energy harvesting hybrid acoustic-optical underwater wireless sensor networks (AO-UWSNs) is proposed. AO-UWSN employs optical communication for higher data rate at a short transmission distance and employs acoustic communication for low data rate and long transmission distance. A hybrid received signal strength (RSS) based localization technique is proposed to localize the nodes in AO-UWSNs. The proposed technique combines the noisy RSS based measurements from acoustic communication and optical communication and estimates the final locations of acoustic-optical sensor nodes. A weighted multiple observations paradigm is proposed for hybrid estimated distances to suppress the noisy observations and give more importance to the accurate observations. Furthermore, the closed form solution for Cramer-Rao lower bound (CRLB) is derived for localization accuracy of the proposed technique.
Energy Harvesting Hybrid Acoustic-Optical Underwater Wireless Sensor Networks Localization
Saeed, Nasir; Celik, Abdulkadir; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim
2017-01-01
Underwater wireless technologies demand to transmit at higher data rate for ocean exploration. Currently, large coverage is achieved by acoustic sensor networks with low data rate, high cost, high latency, high power consumption, and negative impact on marine mammals. Meanwhile, optical communication for underwater networks has the advantage of the higher data rate albeit for limited communication distances. Moreover, energy consumption is another major problem for underwater sensor networks, due to limited battery power and difficulty in replacing or recharging the battery of a sensor node. The ultimate solution to this problem is to add energy harvesting capability to the acoustic-optical sensor nodes. Localization of underwater sensor networks is of utmost importance because the data collected from underwater sensor nodes is useful only if the location of the nodes is known. Therefore, a novel localization technique for energy harvesting hybrid acoustic-optical underwater wireless sensor networks (AO-UWSNs) is proposed. AO-UWSN employs optical communication for higher data rate at a short transmission distance and employs acoustic communication for low data rate and long transmission distance. A hybrid received signal strength (RSS) based localization technique is proposed to localize the nodes in AO-UWSNs. The proposed technique combines the noisy RSS based measurements from acoustic communication and optical communication and estimates the final locations of acoustic-optical sensor nodes. A weighted multiple observations paradigm is proposed for hybrid estimated distances to suppress the noisy observations and give more importance to the accurate observations. Furthermore, the closed form solution for Cramer-Rao lower bound (CRLB) is derived for localization accuracy of the proposed technique. PMID:29278405
Piezoelectric transducer design for a miniaturized injectable acoustic transmitter
DOE Office of Scientific and Technical Information (OSTI.GOV)
Li, Huidong; Jung, Ki Won; Deng, Zhiqun D.
Acoustic telemetry has been an important tool in the last 20 years for studying fish survival and migration behaviors during and after dam passage. This technology uses implantable acoustic transmitters as tags to three-dimensionally track the movement of fish. However, the relatively large weights and sizes of commercially available transmitters limit the populations of fish that could be studied. The surgical implantation procedures required may also injure fish and also incur a significant amount of labor. Therefore, a smaller, lighter, and injectable tag was needed, and similar or better acoustic performance and service life over that provided by existing commercialmore » tags was desired. To develop such a small transmitter, a number of technical challenges, including design optimization of the piezoelectric transducer, needed to be overcome. The goal of our efforts to optimize the transducer focused on improving the average source level in the 180° range in which the transmitter was facing the receiving hydrophone, so as to increase the transmitter’s detection probability. This paper reports the techniques that were explored and developed to achieve this goal. We found that a novel off-center tube transducer improved the average source level of the front half of the transducer by 1.5 dB. An acoustic reflector attached to the back of the transducer also improved the source level by 3 dB when the transducer was pointed toward the receiving hydrophone, although the source level on the sides of the transducer was reduced. We found that too small a gap between the transducer and the component placed behind it resulted in distortion of the beam pattern. To overcome that issue, we connected a tuning inductor in series with the transducer to help optimize the source level. Furthermore, the findings and techniques developed in this work contributed to the successful development and implementation of a new injectable transmitter.« less
Piezoelectric transducer design for a miniaturized injectable acoustic transmitter
Li, Huidong; Jung, Ki Won; Deng, Zhiqun D.
2015-10-07
Acoustic telemetry has been an important tool in the last 20 years for studying fish survival and migration behaviors during and after dam passage. This technology uses implantable acoustic transmitters as tags to three-dimensionally track the movement of fish. However, the relatively large weights and sizes of commercially available transmitters limit the populations of fish that could be studied. The surgical implantation procedures required may also injure fish and also incur a significant amount of labor. Therefore, a smaller, lighter, and injectable tag was needed, and similar or better acoustic performance and service life over that provided by existing commercialmore » tags was desired. To develop such a small transmitter, a number of technical challenges, including design optimization of the piezoelectric transducer, needed to be overcome. The goal of our efforts to optimize the transducer focused on improving the average source level in the 180° range in which the transmitter was facing the receiving hydrophone, so as to increase the transmitter’s detection probability. This paper reports the techniques that were explored and developed to achieve this goal. We found that a novel off-center tube transducer improved the average source level of the front half of the transducer by 1.5 dB. An acoustic reflector attached to the back of the transducer also improved the source level by 3 dB when the transducer was pointed toward the receiving hydrophone, although the source level on the sides of the transducer was reduced. We found that too small a gap between the transducer and the component placed behind it resulted in distortion of the beam pattern. To overcome that issue, we connected a tuning inductor in series with the transducer to help optimize the source level. Furthermore, the findings and techniques developed in this work contributed to the successful development and implementation of a new injectable transmitter.« less
2013-01-01
Background Physical and mental function are strong indicators of disability and mortality. OEF/OIF Veterans returning from deployment have been found to have poorer function than soldiers who have not deployed; however the reasons for this are unknown. Methods A prospective cohort of 790 soldiers was assessed both pre- and immediately after deployment to determine predictors of physical and mental function after war. Results On average, OEF/OIF Veterans showed significant declines in both physical (t=6.65, p<.0001) and mental function (t=7.11, p<.0001). After controlling for pre-deployment function, poorer physical function after deployment was associated with older age, more physical symptoms, blunted systolic blood pressure reactivity and being injured. After controlling for pre-deployment function, poorer mental function after deployment was associated with younger age, lower social desirability, lower social support, greater physical symptoms and greater PTSD symptoms. Conclusions Combat deployment was associated with an immediate decline in both mental and physical function. The relationship of combat deployment to function is complex and influenced by demographic, psychosocial, physiological and experiential factors. Social support and physical symptoms emerged as potentially modifiable factors. PMID:23631419