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.

NASA Glenn's Acoustical Testing Laboratory Awarded Accreditation by the National Voluntary Laboratory Accreditation Program

NASA Technical Reports Server (NTRS)

Akers, James C.; Cooper, Beth A.

2004-01-01

NASA Glenn Research Center's Acoustical Testing Laboratory (ATL) provides a comprehensive array of acoustical testing services, including sound pressure level, sound intensity level, and sound-power-level testing per International Standards Organization (ISO)1 3744. Since its establishment in September 2000, the ATL has provided acoustic emission testing and noise control services for a variety of customers, particularly microgravity space flight hardware that must meet International Space Station acoustic emission requirements. The ATL consists of a 23- by 27- by 20-ft (height) convertible hemi/anechoic test chamber and a separate sound-attenuating test support enclosure. The ATL employs a personal-computer-based data acquisition system that provides up to 26 channels of simultaneous data acquisition with real-time analysis (ref. 4). Specialized diagnostic tools, including a scanning sound-intensity system, allow the ATL's technical staff to support its clients' aggressive low-noise design efforts to meet the space station's acoustic emission requirement. From its inception, the ATL has pursued the goal of developing a comprehensive ISO 17025-compliant quality program that would incorporate Glenn's existing ISO 9000 quality system policies as well as ATL-specific technical policies and procedures. In March 2003, the ATL quality program was awarded accreditation by the National Voluntary Laboratory Accreditation Program (NVLAP) for sound-power-level testing in accordance with ISO 3744. The NVLAP program is administered by the National Institutes of Standards and Technology (NIST) of the U.S. Department of Commerce and provides third-party accreditation for testing and calibration laboratories. There are currently 24 NVLAP-accredited acoustical testing laboratories in the United States. NVLAP accreditation covering one or more specific testing procedures conducted in accordance with established test standards is awarded upon successful completion of an intensive onsite assessment that includes proficiency testing and documentation review. The ATL NVLAP accreditation currently applies specifically to its ISO 3744 soundpower- level determination procedure (see the photograph) and supporting ISO 17025 quality system, although all ATL operations are conducted in accordance with its quality system. The ATL staff is currently developing additional procedures to adapt this quality system to the testing of space flight hardware in accordance with International Space Station acoustic emission requirements.<

KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

Learning Vowel Categories from Maternal Speech in Gurindji Kriol

ERIC Educational Resources Information Center

Jones, Caroline; Meakins, Felicity; Muawiyath, Shujau

2012-01-01

Distributional learning is a proposal for how infants might learn early speech sound categories from acoustic input before they know many words. When categories in the input differ greatly in relative frequency and overlap in acoustic space, research in bilingual development suggests that this affects the course of development. In the present…

Acoustic levitation and manipulation for space applications

NASA Technical Reports Server (NTRS)

Wang, T. G.

1979-01-01

A wide spectrum of experiments to be performed in space in a microgravity environment require levitation and manipulation of liquid or molten samples. A novel acoustic method has been developed at JPL for controlling liquid samples without physical contacts. This method utilizes the static pressure generated by three orthogonal acoustic standing waves excited within an enclosure. Furthermore, this method will allow the sample to be rotated and/or oscillated by modifying the phase angles and/or the amplitude of the acoustic field. This technique has been proven both in our laboratory and in a microgravity environment provided by KC-135 flights. Samples placed within our chamber driven at (1,0,0), (0,1,0), and (0,0,1), modes were indeed levitated, rotated, and oscillated.

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

PubMed

Jayachandran, V; Bonilha, M W

2003-03-01

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

Soundscape of Urban Open Spaces in Hong Kong

NASA Astrophysics Data System (ADS)

Lin, Hui

This study aims to investigate the soundscape of urban open spaces in Hong Kong. Open space in densely populated cities has been considered as an important asset for urban inhabitants in that they afford opportunities for leisure, recreation and an active involvement with nature. For quite a long time, visual aesthetic was the dominant consideration in open space design and other senses were given less concern. Continuous stream of attention-demanding sounds from the noisy environment may bombard these open spaces, rendering them no longer able to satisfy the eye alone. Sound and consequently the acoustic environment are receiving increasing attention. This study used noise mapping technique supplemented by GIS spatial analysis tools to delineate quiet open spaces with traffic noise exposure less than 60 dB (A) L10, 1h and conducted field observations to determine their usages. The identified quiet open spaces are either concentrated in hilly and remote areas with low accessibility, or sporadically scattered among tall buildings. Some large urban parks and small sitting-out areas are even located in the center of the city. Larger open spaces serve group visits, such as hiking and sightseeing, while smaller ones are easily accessible to local residents for social and recreational purposes. The acoustic environment III urban open spaces varies with space and time. To characterize the acoustic quality of soundscapes in the quiet open spaces, sound walk and field recording were undertaken place in 25 selected study sites. Despite the dominance of traffic noise, soundscapes in the urban open spaces are also shaped by natural sounds. Sounds from birds and water are common and prevalent particularly in gardens and playgrounds. Soundscape approach is a human-centered point of view. How the visitors perceive and evaluate sounds and the acoustic quality has great implication for soundscape design. On-site interview of 1,610 visitors unravels human preference of individual sounds and evaluation of the acoustic quality. Sounds from bird, wind and water are most preferred, while mechanical sounds and road traffic noise are least favored. Human voice is rated in between. Brown's soundscape evaluation framework was substantiated by data collected in this study highlighting tbe importance of context and presence of wanted and unwanted sounds on subjective evaluation of the acoustic quality. Ordinal Logistic Regression models were developed with significant independent variables, including social-demographic factors, acoustic parameters, visiting habits and presence of wanted and unwanted sounds. Research findings have great implications for soundscape design of open spaces in compact cities. A properly designed open space offers a comfortable setting for relief, retreat and rejuvenation from tbe urban life. Endeavors to improve the acoustic quality in the urban open spaces will make cities more livable and sustainable.

Acoustic Measurements of Small Solid Rocket Motor

NASA Technical Reports Server (NTRS)

Vargas, Magda B.; Kenny, R. Jeremy

2010-01-01

Rocket acoustic noise can induce loads and vibration on the vehicle as well as the surrounding structures. Models have been developed to predict these acoustic loads based on scaling existing solid rocket motor data. The NASA Marshall Space Flight Center acoustics team has measured several small solid rocket motors (thrust below 150,000 lbf) to anchor prediction models. This data will provide NASA the capability to predict the acoustic environments and consequent vibro-acoustic response of larger rockets (thrust above 1,000,000 lbf) such as those planned for the NASA Constellation program. This paper presents the methods used to measure acoustic data during the static firing of small solid rocket motors and the trends found in the data.

ASTRYD: A new numerical tool for aircraft cabin and environmental noise prediction

NASA Astrophysics Data System (ADS)

Berhault, J.-P.; Venet, G.; Clerc, C.

ASTRYD is an analytical tool, developed originally for underwater applications, that computes acoustic pressure distribution around three-dimensional bodies in closed spaces like aircraft cabins. The program accepts data from measurements or other simulations, processes them in the time domain, and delivers temporal evolutions of the acoustic pressures and accelerations, as well as the radiated/diffracted pressure at arbitrary points located in the external/internal space. A typical aerospace application is prediction of acoustic load on satellites during the launching phase. An aeronautic application is engine noise distribution on a business jet body for prediction of environmental and cabin noise.

KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge as others stand by in a watercraft during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge as others stand by in a watercraft during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

Review of Progress in Acoustic Levitation

NASA Astrophysics Data System (ADS)

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

2018-04-01

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

Analytical model of the structureborne interior noise induced by a propeller wake

NASA Technical Reports Server (NTRS)

Junger, M. C.; Garrelick, J. M.; Martinez, R.; Cole, J. E., III

1984-01-01

The structure-borne contribution to the interior noise that is induced by the propeller wake acting on the wing was studied. Analytical models were developed to describe each aspect of this path including the excitation loads, the wing and fuselage structures, and the interior acoustic space. The emphasis is on examining a variety of parameters, and as a result different models were developed to examine specific parameters. The excitation loading on the wing by the propeller wake is modeled by a distribution of rotating potential vortices whose strength is related to the thrust per blade. The response of the wing to this loading is examined using beam models. A model of a beam structurally connected to a cylindrical shell with an internal acoustic fluid was developed to examine the coupling of energy from the wing to the interior space. The model of the acoustic space allows for arbitrary end conditions (e.g., rigid or vibrating end caps). Calculations are presented using these models to compare with a laboratory test configuration as well as for parameters of a prop-fan aircraft.

Vibrations and structureborne noise in space station

NASA Technical Reports Server (NTRS)

Vaicaitis, R.; Lyrintzis, C. S.; Bofilios, D. A.

1987-01-01

Analytical models were developed to predict vibrations and structureborne noise generation of cylindrical and rectangular acoustic enclosures. These models are then used to determine structural vibration levels and interior noise to random point input forces. The guidelines developed could provide preliminary information on acoustical and vibrational environments in space station habitability modules under orbital operations. The structural models include single wall monocoque shell, double wall shell, stiffened orthotropic shell, descretely stiffened flat panels, and a coupled system composed of a cantilever beam structure and a stiffened sidewall. Aluminum and fiber reinforced composite materials are considered for single and double wall shells. The end caps of the cylindrical enclosures are modeled either as single or double wall circular plates. Sound generation in the interior space is calculated by coupling the structural vibrations to the acoustic field in the enclosure. Modal methods and transfer matrix techniques are used to obtain structural vibrations. Parametric studies are performed to determine the sensitivity of interior noise environment to changes in input, geometric and structural conditions.

Noise Control in Space Shuttle Orbiter

NASA Technical Reports Server (NTRS)

Goodman, Jerry R.

2009-01-01

Acoustic limits in habitable space enclosures are required to ensure crew safety, comfort, and habitability. Noise control is implemented to ensure compliance with the acoustic requirements. The purpose of this paper is to describe problems with establishing acoustic requirements and noise control efforts, and present examples of noise control treatments and design applications used in the Space Shuttle Orbiter. Included is the need to implement the design discipline of acoustics early in the design process, and noise control throughout a program to ensure that limits are met. The use of dedicated personnel to provide expertise and oversight of acoustic requirements and noise control implementation has shown to be of value in the Space Shuttle Orbiter program. It is concluded that to achieve acceptable and safe noise levels in the crew habitable space, early resolution of acoustic requirements and implementation of effective noise control efforts are needed. Management support of established acoustic requirements and noise control efforts is essential.

Overview of NASA Glenn Seal Program

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Proctor, Margaret P.; Dunlap, Patrick H., Jr.; Delgado, Irebert; DeMange, Jeffrey J.; Daniels, Christopher C.; Lattime, Scott B.

2003-01-01

The Seal Team is divided into four primary areas. These areas include turbine engine seal development, structural seal development, acoustic seal development, and adaptive seal development. The turbine seal area focuses on high temperature, high speed shaft seals for secondary air system flow management. The structural seal area focuses on high temperature, resilient structural seals required to accommodate large structural distortions for both space- and aero-applications. Our goal in the acoustic seal project is to develop non-contacting, low leakage seals exploiting the principles of advanced acoustics. We are currently investigating a new acoustic field known as Resonant Macrosonic Synthesis (RMS) to see if we can harness the large acoustic standing pressure waves to form an effective air-barrier/seal. Our goal in the adaptive seal project is to develop advanced sealing approaches for minimizing blade-tip (shroud) or interstage seal leakage. We are planning on applying either rub-avoidance or regeneration clearance control concepts (including smart structures and materials) to promote higher turbine engine efficiency and longer service lives.

KENNEDY SPACE CENTER, FLA. - Researchers conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Researchers conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

Overview of the Acoustic Testing of the European Service Module Structural Test Article (E-STA)

NASA Technical Reports Server (NTRS)

Hughes, William; Fogt, Vince; Le Plenier, Cyprien; Duval, Francois; Durand, Jean-Francois; Staab, Lucas D.; Hozman, Aron; Mcnelis, Anne; Bittinger, Samantha; Thirkettle, Anthony;

Overview of the Acoustic Testing of the European Service Module Structural Test Article (E-STA)

NASA Technical Reports Server (NTRS)

Hughes, William; Le Plenier, Cyprien; Duval, Francois; Staab, Lucas; Hozman, Aron; Thirkettle, Anthony; Fogt, Vincent; Durand, Jean-Francois; McNelis, Anne; Bittinger, Samantha;

Acoustic interference and recognition space within a complex assemblage of dendrobatid frogs

PubMed Central

Amézquita, Adolfo; Flechas, Sandra Victoria; Lima, Albertina Pimentel; Gasser, Herbert; Hödl, Walter

2011-01-01

In species-rich assemblages of acoustically communicating animals, heterospecific sounds may constrain not only the evolution of signal traits but also the much less-studied signal-processing mechanisms that define the recognition space of a signal. To test the hypothesis that the recognition space is optimally designed, i.e., that it is narrower toward the species that represent the higher potential for acoustic interference, we studied an acoustic assemblage of 10 diurnally active frog species. We characterized their calls, estimated pairwise correlations in calling activity, and, to model the recognition spaces of five species, conducted playback experiments with 577 synthetic signals on 531 males. Acoustic co-occurrence was not related to multivariate distance in call parameters, suggesting a minor role for spectral or temporal segregation among species uttering similar calls. In most cases, the recognition space overlapped but was greater than the signal space, indicating that signal-processing traits do not act as strictly matched filters against sounds other than homospecific calls. Indeed, the range of the recognition space was strongly predicted by the acoustic distance to neighboring species in the signal space. Thus, our data provide compelling evidence of a role of heterospecific calls in evolutionarily shaping the frogs' recognition space within a complex acoustic assemblage without obvious concomitant effects on the signal. PMID:21969562

Developing better artificial bones.

PubMed

Flinn, Edward D

2003-01-01

Researchers at the Center for Commercial Applications of Combustion in Space at the Colorado School of Mines are preparing the Space-DRUMS (Dynamically Responding Ultrasonic Matrix Systems) materials processing facility for transport to the International Space Station. The Space-DRUMS uses acoustic pressure beams to maintain the position of a suspended liquid or solid. Space-DRUMS will be used to extend experiments with tricalcium phosphate in the development of artificial bone material.

Case studies of pre-engineered and manufactured sound isolation rooms for music practice and radio broadcast

NASA Astrophysics Data System (ADS)

Probst, Ron N.; Rypka, Dann

2005-09-01

Pre-engineered and manufactured sound isolation rooms were developed to ensure guaranteed sound isolation while offering the unique ability to be disassembled and relocated without loss of acoustic performance. Case studies of pre-engineered sound isolation rooms used for music practice and various radio broadcast purposes are highlighted. Three prominent universities wrestle with the challenges of growth and expansion while responding to the specialized acoustic requirements of these spaces. Reduced state funding for universities requires close examination of all options while ensuring sound isolation requirements are achieved. Changing curriculum, renovation, and new construction make pre-engineered and manufactured rooms with guaranteed acoustical performance good investments now and for the future. An added benefit is the optional integration of active acoustics to provide simulations of other spaces or venues along with the benefit of sound isolation.

Documentation of the space station/aircraft acoustic apparatus

NASA Technical Reports Server (NTRS)

Clevenson, Sherman A.

1987-01-01

This paper documents the design and construction of the Space Station/Aircraft Acoustic Apparatus (SS/AAA). Its capabilities both as a space station acoustic simulator and as an aircraft acoustic simulator are described. Also indicated are the considerations which ultimately resulted in man-rating the SS/AAA. In addition, the results of noise surveys and reverberation time and absorption coefficient measurements are included.

Acoustical Testing Laboratory Developed to Support the Low-Noise Design of Microgravity Space Flight Hardware

NASA Technical Reports Server (NTRS)

Cooper, Beth A.

2001-01-01

The NASA John H. Glenn Research Center at Lewis Field has designed and constructed an Acoustical Testing Laboratory to support the low-noise design of microgravity space flight hardware. This new laboratory will provide acoustic emissions testing and noise control services for a variety of customers, particularly for microgravity space flight hardware that must meet International Space Station limits on noise emissions. These limits have been imposed by the space station to support hearing conservation, speech communication, and safety goals as well as to prevent noise-induced vibrations that could impact microgravity research data. The Acoustical Testing Laboratory consists of a 23 by 27 by 20 ft (height) convertible hemi/anechoic chamber and separate sound-attenuating test support enclosure. Absorptive 34-in. fiberglass wedges in the test chamber provide an anechoic environment down to 100 Hz. A spring-isolated floor system affords vibration isolation above 3 Hz. These criteria, along with very low design background levels, will enable the acquisition of accurate and repeatable acoustical measurements on test articles, up to a full space station rack in size, that produce very little noise. Removable floor wedges will allow the test chamber to operate in either a hemi/anechoic or anechoic configuration, depending on the size of the test article and the specific test being conducted. The test support enclosure functions as a control room during normal operations but, alternatively, may be used as a noise-control enclosure for test articles that require the operation of noise-generating test support equipment.

Dual Mode Thin Film Bulk Acoustic Resonators (FBARs) Based on AlN, ZnO and GaN Films with Tilted c-Axis Orientation

DTIC Science & Technology

2010-01-01

TERMS MEMS , acoustic wave devices, acoustic wave sensors Qing-Ming Wang University of Pittsburgh 123 University Place University Club Pittsburgh, PA...resonators,” Proc. SPIE Vol. 6223, 62230I, Micro ( MEMS ) and Nanotechnologies for Space Applications; Thomas George, Zhong-Yang Cheng; Eds. (May...microelectromechanical resonators has been recognized as a technological challenge in the current microelectronics and MEMS development. The

Development of Sound Localization Strategies in Children with Bilateral Cochlear Implants

PubMed Central

Zheng, Yi; Godar, Shelly P.; Litovsky, Ruth Y.

2015-01-01

Localizing sounds in our environment is one of the fundamental perceptual abilities that enable humans to communicate, and to remain safe. Because the acoustic cues necessary for computing source locations consist of differences between the two ears in signal intensity and arrival time, sound localization is fairly poor when a single ear is available. In adults who become deaf and are fitted with cochlear implants (CIs) sound localization is known to improve when bilateral CIs (BiCIs) are used compared to when a single CI is used. The aim of the present study was to investigate the emergence of spatial hearing sensitivity in children who use BiCIs, with a particular focus on the development of behavioral localization patterns when stimuli are presented in free-field horizontal acoustic space. A new analysis was implemented to quantify patterns observed in children for mapping acoustic space to a spatially relevant perceptual representation. Children with normal hearing were found to distribute their responses in a manner that demonstrated high spatial sensitivity. In contrast, children with BiCIs tended to classify sound source locations to the left and right; with increased bilateral hearing experience, they developed a perceptual map of space that was better aligned with the acoustic space. The results indicate experience-dependent refinement of spatial hearing skills in children with CIs. Localization strategies appear to undergo transitions from sound source categorization strategies to more fine-grained location identification strategies. This may provide evidence for neural plasticity, with implications for training of spatial hearing ability in CI users. PMID:26288142

Development of Sound Localization Strategies in Children with Bilateral Cochlear Implants.

PubMed

Zheng, Yi; Godar, Shelly P; Litovsky, Ruth Y

2015-01-01

Localizing sounds in our environment is one of the fundamental perceptual abilities that enable humans to communicate, and to remain safe. Because the acoustic cues necessary for computing source locations consist of differences between the two ears in signal intensity and arrival time, sound localization is fairly poor when a single ear is available. In adults who become deaf and are fitted with cochlear implants (CIs) sound localization is known to improve when bilateral CIs (BiCIs) are used compared to when a single CI is used. The aim of the present study was to investigate the emergence of spatial hearing sensitivity in children who use BiCIs, with a particular focus on the development of behavioral localization patterns when stimuli are presented in free-field horizontal acoustic space. A new analysis was implemented to quantify patterns observed in children for mapping acoustic space to a spatially relevant perceptual representation. Children with normal hearing were found to distribute their responses in a manner that demonstrated high spatial sensitivity. In contrast, children with BiCIs tended to classify sound source locations to the left and right; with increased bilateral hearing experience, they developed a perceptual map of space that was better aligned with the acoustic space. The results indicate experience-dependent refinement of spatial hearing skills in children with CIs. Localization strategies appear to undergo transitions from sound source categorization strategies to more fine-grained location identification strategies. This may provide evidence for neural plasticity, with implications for training of spatial hearing ability in CI users.

14 CFR 25.856 - Thermal/Acoustic insulation materials.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Thermal/Acoustic insulation materials. 25.856 Section 25.856 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....856 Thermal/Acoustic insulation materials. (a) Thermal/acoustic insulation material installed in the...

14 CFR 25.856 - Thermal/Acoustic insulation materials.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Thermal/Acoustic insulation materials. 25.856 Section 25.856 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....856 Thermal/Acoustic insulation materials. (a) Thermal/acoustic insulation material installed in the...

14 CFR 23.856 - Thermal/acoustic insulation materials.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Thermal/acoustic insulation materials. 23.856 Section 23.856 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Construction Fire Protection § 23.856 Thermal/acoustic insulation materials. Thermal/acoustic insulation...

14 CFR 23.856 - Thermal/acoustic insulation materials.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Thermal/acoustic insulation materials. 23.856 Section 23.856 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Construction Fire Protection § 23.856 Thermal/acoustic insulation materials. Thermal/acoustic insulation...

14 CFR 23.856 - Thermal/acoustic insulation materials.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Thermal/acoustic insulation materials. 23.856 Section 23.856 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Construction Fire Protection § 23.856 Thermal/acoustic insulation materials. Thermal/acoustic insulation...

Tracking marine mammals and ships with small and large-aperture hydrophone arrays

NASA Astrophysics Data System (ADS)

Gassmann, Martin

Techniques for passive acoustic tracking in all three spatial dimensions of marine mammals and ships were developed for long-term acoustic datasets recorded continuously over months using custom-designed arrays of underwater microphones (hydrophones) with spacing ranging from meters to kilometers. From the three-dimensional tracks, the acoustical properties of toothed whales and ships, such as sound intensity and directionality, were estimated as they are needed for the passive acoustic abundance estimation of toothed whales and for a quantitative description of the contribution of ships to the underwater soundscape. In addition, the tracks of the toothed whales reveal their underwater movements and demonstrate the potential of the developed tracking techniques to investigate their natural behavior and responses to sound generated by human activity, such as from ships or military SONAR. To track the periodically emitted echolocation sounds of toothed whales in an acoustically refractive environment in the upper ocean, a propagation-model based technique was developed for a hydrophone array consisting of one vertical and two L-shaped subarrays deployed from the floating instrument platform R/P FLIP. The technique is illustrated by tracking a group of five shallow-diving killer whales showing coordinated behavior. The challenge of tracking the highly directional echolocation sounds of deep-diving (< 1 km) toothed whales, in particular Cuvier's beaked whales, was addressed by embedding volumetric small-aperture (≈ 1 m element spacing) arrays into a large-aperture (≈ 1 km element spacing) seafloor array to reduce the minimum number of required receivers from five to two. The capabilities of this technique are illustrated by tracking several groups of up to three individuals over time periods from 10 min to 33 min within an area of 20 km2 in the Southern California Bight. To track and measure the underwater radiated sound of ships, a frequency domain beamformer was implemented for a volumetric hydrophone array (< 2 m element spacing) that was coupled to an autonomous acoustic seafloor recorder. This allows for the tracking and measurement of underwater radiated sound from ships of opportunity with a single instrument deployment and without depending on track information from the automatic information system (AIS).

The Development of Voiceless Sibilant Fricatives in Putonghua-Speaking Children

ERIC Educational Resources Information Center

Li, Fangfang; Munson, Benjamin

2016-01-01

Purpose The aims of the present study are (a) to quantify the developmental sequence of fricative mastery in Putonghua-speaking children and discuss the observed pattern in relation to existing theoretical positions, and (b) to describe the acquisition of the fine-articulatory/acoustic details of fricatives in the multidimensional acoustic space.…

New approaches for automatic threedimensional source localization of acoustic emissions--Applications to concrete specimens.

PubMed

Kurz, Jochen H

2015-12-01

The task of locating a source in space by measuring travel time differences of elastic or electromagnetic waves from the source to several sensors is evident in varying fields. The new concepts of automatic acoustic emission localization presented in this article are based on developments from geodesy and seismology. A detailed description of source location determination in space is given with the focus on acoustic emission data from concrete specimens. Direct and iterative solvers are compared. A concept based on direct solvers from geodesy extended by a statistical approach is described which allows a stable source location determination even for partly erroneous onset times. The developed approach is validated with acoustic emission data from a large specimen leading to travel paths up to 1m and therefore to noisy data with errors in the determined onsets. The adaption of the algorithms from geodesy to the localization procedure of sources of elastic waves offers new possibilities concerning stability, automation and performance of localization results. Fracture processes can be assessed more accurately. Copyright © 2015 Elsevier B.V. All rights reserved.

Multimode Acoustic Research

NASA Technical Reports Server (NTRS)

Barmatz, M.

1985-01-01

There is a need for high temperature containerless processing facilities that can efficiently position and manipulate molten samples in the reduced gravity environment of space. The goal of the research is to develop sophisticated high temperature manipulation capabilities such as selection of arbitrary axes rotation and rapid sample cooling. This program will investigate new classes of acoustic levitation in rectangular, cylindrical and spherical geometries. The program tasks include calculating theoretical expressions of the acoustic forces in these geometries for the excitation of up to three acoustic modes (multimodes). These calculations are used to: (1) determine those acoustic modes that produce stable levitation, (2) isolate the levitation and rotation capabilities to produce more than one axis of rotation, and (3) develop methods to translate samples down long tube cylindrical chambers. Experimental levitators will then be constructed to verify the stable levitation and rotation predictions of the models.

Virtual auditorium concepts for exhibition halls

NASA Astrophysics Data System (ADS)

Evans, Jack; Himmel, Chad; Knight, Sarah

2002-11-01

Many communities lack good performance facilities for symphonic music, opera, dramatic and musical arts, but have basic convention, exhibition or assembly spaces. It should be possible to develop performance space environments within large multipurpose facilities that will accommodate production and presentation of dramatic arts. Concepts for moderate-cost, temporary enhancements that transform boxy spaces into more intimate, acoustically articulated venues will be presented. Acoustical criteria and design parameters will be discussed in the context of creating a virtual auditorium within the building envelope. Physical, economic, and logistical limitations affect implementation. Sound reinforcement system augmentation can supplement the room conversion. Acceptable control of reflection patterns, reverberation, and to some extent, ambient noise, may be achieved with an array of nonpermanent reflector and absorber elements. These elements can sculpture an enclosure to approach the shape and acoustic characteristics of an auditorium. Plan and section illustrations will be included.

KENNEDY SPACE CENTER, FLA. - Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

RS-88 Pad Abort Demonstrator Thrust Chamber Assembly Testing at NASA Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Farr, Rebecca A.; Sanders, Timothy M.

1990-01-01

This paper documents the effort conducted to collect hot-tire dynamic and acoustics environments data during 50,000-lb thrust lox-ethanol hot-fire rocket testing at NASA Marshall Space Flight Center (MSFC) in November-December 2003. This test program was conducted during development testing of the Boeing Rocketdyne RS-88 development engine thrust chamber assembly (TCA) in support of the Orbital Space Plane (OSP) Crew Escape System Propulsion (CESP) Program Pad Abort Demonstrator (PAD). In addition to numerous internal TCA and nozzle measurements, induced acoustics environments data were also collected. Provided here is an overview of test parameters, a discussion of the measurements, test facility systems and test operations, and a quality assessment of the data collected during this test program.

Containerless Processing Studies in the MSFC Electrostatic Levitator

NASA Technical Reports Server (NTRS)

Rogers, J. R.; SanSoucie, M. P.

2012-01-01

Levitation or containerless processing represents an important tool in materials research. Levitated specimens are free from contact with a container, which permits studies of deeply undercooled melts, and high-temperature, highly reactive materials. Containerless processing provides data for studies of thermophysical properties, phase equilibria, metastable state formation, microstructure formation, undercooling, and nucleation. Levitation techniques include: acoustic, aero-acoustic, electromagnetic, and electrostatic. In microgravity, levitation can be achieved with greatly reduced positioning forces. Microgravity also reduces the effects of buoyancy and sedimentation in melts. The European Space Agency (ESA) and the German Aerospace Center (DLR) jointly developed an electromagnetic levitator facility (MSL-EML) for containerless materials processing in space. The MSL-EML will be accommodated in the European Columbus Facility on the International Space Station (ISS). The electrostatic levitator (ESL) facility at the Marshall Space Flight Center provides support for the development of containerless processing studies for the ISS. The capabilities of the facility and recent results will be discussed.

Acoustical considerations for secondary uses of government facilities

NASA Astrophysics Data System (ADS)

Evans, Jack B.

2003-10-01

Government buildings are by their nature, public and multi-functional. Whether in meetings, presentations, documentation processing, work instructions or dispatch, speech communications are critical. Full-time occupancy facilities may require sleep or rest areas adjacent to active spaces. Rooms designed for some other primary use may be used for public assembly, receptions or meetings. In addition, environmental noise impacts to the building or from the building should be considered, especially where adjacent to hospitals, hotels, apartments or other urban sensitive land uses. Acoustical criteria and design parameters for reverberation, background noise and sound isolation should enhance speech intelligibility and privacy. This presentation looks at unusual spaces and unexpected uses of spaces with regard to room acoustics and noise control. Examples of various spaces will be discussed, including an atrium used for reception and assembly, multi-jurisdictional (911) emergency control center, frequent or long-duration use of emergency generators, renovations of historically significant buildings, and the juxtaposition of acoustically incompatible functions. Brief case histories of acoustical requirements, constraints and design solutions will be presented, including acoustical measurements, plan illustrations and photographs. Acoustical criteria for secondary functional uses of spaces will be proposed.

Capabilities, Design, Construction and Commissioning of New Vibration, Acoustic, and Electromagnetic Capabilities Added to the World's Largest Thermal Vacuum Chamber at NASA's Space Power Facility

NASA Technical Reports Server (NTRS)

Motil, Susan M.; Ludwiczak, Damian R.; Carek, Gerald A.; Sorge, Richard N.; Free, James M.; Cikanek, Harry A., III

2011-01-01

NASA s human space exploration plans developed under the Exploration System Architecture Studies in 2005 included a Crew Exploration Vehicle launched on an Ares I launch vehicle. The mass of the Crew Exploration Vehicle and trajectory of the Ares I coupled with the need to be able to abort across a large percentage of the trajectory generated unprecedented testing requirements. A future lunar lander added to projected test requirements. In 2006, the basic test plan for Orion was developed. It included several types of environment tests typical of spacecraft development programs. These included thermal-vacuum, electromagnetic interference, mechanical vibration, and acoustic tests. Because of the size of the vehicle and unprecedented acoustics, NASA conducted an extensive assessment of options for testing, and as result, chose to augment the Space Power Facility at NASA Plum Brook Station, of the John H. Glenn Research Center to provide the needed test capabilities. The augmentation included designing and building the World s highest mass capable vibration table, the highest power large acoustic chamber, and adaptation of the existing World s largest thermal vacuum chamber as a reverberant electromagnetic interference test chamber. These augmentations were accomplished from 2007 through early 2011. Acceptance testing began in Spring 2011 and will be completed in the Fall of 2011. This paper provides an overview of the capabilities, design, construction and acceptance of this extraordinary facility.

Passive Acoustic Methods for Tracking Marine Mammals Using Widely-Spaced Bottom-Mounted Hydrophones

DTIC Science & Technology

2009-09-30

HARP [Wiggins 2007] at about 400m depth on the summit of Cross Seamount , approximately 290 km south of the Hawaiian island of Oahu (dataset provided...based tracking methods developed in this project are used to support ONR award N000140910489: The ecology and acoustic behavior of minke whales in the ...N000140811142 http://www.soest.hawaii.edu/ore/faculty/nosal LONG-TERM GOALS The long-term goal of this project is to improve passive acoustic methods

The social effects of poor classroom acoustics on students and The District of Columbia Public Schools demonstration of support through mandating the ANSI Classroom Acoustics standard

NASA Astrophysics Data System (ADS)

Ellis, Donna

2002-11-01

The effects that poor acoustics have on students extend beyond the classroom. This paper is to discuss the immediate and long-term results that inadequate acoustical design in the educational setting has on academic and social development and how the District of Columbia Public Schools (DCPS) are contributing to the classroom acoustic movement. DCPS is taking a pro-active stance in educational acoustics by mandating the ANSI Draft S12.60-200X classroom acoustic standard in the transformation of ten schools a year for the next ten to fifteen years. Synthesizing the ANSI S12 standard with the DCPS Design Guidelines describes explanation of how to design for appropriate acoustics in all core-learning spaces. Examples of the existing conditions of the facilities and acoustical remediation for new and historical preservation projects will be demonstrated. In addition, experience will be shared on the International Building Code Council hearings for classroom acoustics.

Examining Acoustic and Kinematic Measures of Articulatory Working Space: Effects of Speech Intensity

ERIC Educational Resources Information Center

Whitfield, Jason A.; Dromey, Christopher; Palmer, Panika

2018-01-01

Purpose: The purpose of this study was to examine the effect of speech intensity on acoustic and kinematic vowel space measures and conduct a preliminary examination of the relationship between kinematic and acoustic vowel space metrics calculated from continuously sampled lingual marker and formant traces. Method: Young adult speakers produced 3…

Comparison of the Effects of using Tygon Tubing in Rocket Propulsion Ground Test Pressure Transducer Measurements

NASA Technical Reports Server (NTRS)

Farr, Rebecca A.; Wiley, John T.; Vitarius, Patrick

2005-01-01

This paper documents acoustics environments data collected during liquid oxygen- ethanol hot-fire rocket testing at NASA Marshall Space Flight Center in November- December 2003. The test program was conducted during development testing of the RS-88 development engine thrust chamber assembly in support of the Orbital Space Plane Crew Escape System Propulsion Program Pad Abort Demonstrator. In addition to induced environments analysis support, coincident data collected using other sensors and methods has allowed benchmarking of specific acoustics test measurement methodologies during propulsion tests. Qualitative effects on data characteristics caused by using tygon sense lines of various lengths in pressure transducer measurements is discussed here.

a Study of Ultrasonic Wave Propagation Through Parallel Arrays of Immersed Tubes

NASA Astrophysics Data System (ADS)

Cocker, R. P.; Challis, R. E.

1996-06-01

Tubular array structures are a very common component in industrial heat exchanging plant and the non-destructive testing of these arrays is essential. Acoustic methods using microphones or ultrasound are attractive but require a thorough understanding of the acoustic properties of tube arrays. This paper details the development and testing of a small-scale physical model of a tube array to verify the predictions of a theoretical model for acoustic propagation through tube arrays developed by Heckl, Mulholland, and Huang [1-5] as a basis for the consideration of small-scale physical models in the development of non-destructive testing procedures for tube arrays. Their model predicts transmission spectra for plane waves incident on an array of tubes arranged in straight rows. Relative transmission is frequency dependent with bands of high and low attenuation caused by resonances within individual tubes and between tubes in the array. As the number of rows in the array increases the relative transmission spectrum becomes more complex, with increasingly well-defined bands of high and low attenuation. Diffraction of acoustic waves with wavelengths less than the tube spacing is predicted and appears as step reductions in the transmission spectrum at frequencies corresponding to integer multiples of the tube spacing. Experiments with the physical model confirm the principle features of the theoretical treatment.

Aural localization of silent objects by active human biosonar: neural representations of virtual echo-acoustic space.

PubMed

Wallmeier, Ludwig; Kish, Daniel; Wiegrebe, Lutz; Flanagin, Virginia L

2015-03-01

Some blind humans have developed the remarkable ability to detect and localize objects through the auditory analysis of self-generated tongue clicks. These echolocation experts show a corresponding increase in 'visual' cortex activity when listening to echo-acoustic sounds. Echolocation in real-life settings involves multiple reflections as well as active sound production, neither of which has been systematically addressed. We developed a virtualization technique that allows participants to actively perform such biosonar tasks in virtual echo-acoustic space during magnetic resonance imaging (MRI). Tongue clicks, emitted in the MRI scanner, are picked up by a microphone, convolved in real time with the binaural impulse responses of a virtual space, and presented via headphones as virtual echoes. In this manner, we investigated the brain activity during active echo-acoustic localization tasks. Our data show that, in blind echolocation experts, activations in the calcarine cortex are dramatically enhanced when a single reflector is introduced into otherwise anechoic virtual space. A pattern-classification analysis revealed that, in the blind, calcarine cortex activation patterns could discriminate left-side from right-side reflectors. This was found in both blind experts, but the effect was significant for only one of them. In sighted controls, 'visual' cortex activations were insignificant, but activation patterns in the planum temporale were sufficient to discriminate left-side from right-side reflectors. Our data suggest that blind and echolocation-trained, sighted subjects may recruit different neural substrates for the same active-echolocation task. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Generation of acoustic self-bending and bottle beams by phase engineering

NASA Astrophysics Data System (ADS)

Zhang, Peng; Li, Tongcang; Zhu, Jie; Zhu, Xuefeng; Yang, Sui; Wang, Yuan; Yin, Xiaobo; Zhang, Xiang

2014-07-01

Directing acoustic waves along curved paths is critical for applications such as ultrasound imaging, surgery and acoustic cloaking. Metamaterials can direct waves by spatially varying the material properties through which the wave propagates. However, this approach is not always feasible, particularly for acoustic applications. Here we demonstrate the generation of acoustic bottle beams in homogeneous space without using metamaterials. Instead, the sound energy flows through a three-dimensional curved shell in air leaving a close-to-zero pressure region in the middle, exhibiting the capability of circumventing obstacles. By designing the initial phase, we develop a general recipe for creating self-bending wave packets, which can set acoustic beams propagating along arbitrary prescribed convex trajectories. The measured acoustic pulling force experienced by a rigid ball placed inside such a beam confirms the pressure field of the bottle. The demonstrated acoustic bottle and self-bending beams have potential applications in medical ultrasound imaging, therapeutic ultrasound, as well as acoustic levitations and isolations.

Effect of urban noise to the acoustical performance of the secondary school’s learning spaces - A case study in Batu Pahat.

NASA Astrophysics Data System (ADS)

Tong, Y. G.; Abu Bakar, H.; Mohd. Sari, K. A.; Ewon, U.; Labeni, M. N.; Fauzan, N. F. A.

2017-11-01

Classrooms and laboratories are important spaces that use for teaching and learning process in the school. Therefore, good acoustical performances of these spaces are essential to ensure the speech or message from the teacher can be delivered to the students effectively and clearly. The aims of this study is to determine the acoustical performance of the teaching and learning spaces in public school that situated near to the traffic roads. The acoustical performance of the classrooms and laboratories at Sekolah Menengah Kebangsaan Convent Batu Pahat was evaluated in this study. The reverberation time and ambient noise of these learning spaces which are the main parameters for classroom design criteria were evaluated. Field measurements were carried out inside six classrooms and four laboratories unoccupied furnished according to the international standards. The acoustical performances of the tested learning spaces were poor where the noise criteria and reverberation times inside the measured classrooms and laboratories were higher than recommended values.

Twin Jet Effects on Noise of Round and Rectangular Jets: Experiment and Model

NASA Technical Reports Server (NTRS)

Bozak, Rick

2014-01-01

Many subsonic and supersonic aircraft concepts proposed by NASA's Fundamental Aeronautics Program have asymmetric, integrated propulsion systems. The asymmetries in the exhaust of these propulsion systems create an asymmetric acoustic field. The asymmetries investigated in the current study are from twin jets and rectangular nozzles. Each effect produces its own variation of the acoustic field. An empirical model was developed to predict the acoustic field variation from round twin jets with twin jet spacing from 2.6 to 5.6, where s is the center-to-center spacing over the jet diameter. The model includes parameters to account for the effects of twin jet spacing, jet static temperature ratio, flight Mach number, frequency, and observer angle (both polar and azimuthal angles). The model was then applied to twin 2:1 and 8:1 aspect ratio nozzles to determine the impact of jet aspect ratio. For the round and rectangular jets, the use of the model reduces the average magnitude of the error over all frequencies, observation angles, and jet spacings by approximately 0.5dB when compared against the assumption of adding two jets incoherently.

Baryon acoustic oscillations in 2D. II. Redshift-space halo clustering in N-body simulations

NASA Astrophysics Data System (ADS)

Nishimichi, Takahiro; Taruya, Atsushi

2011-08-01

We measure the halo power spectrum in redshift space from cosmological N-body simulations, and test the analytical models of redshift distortions particularly focusing on the scales of baryon acoustic oscillations. Remarkably, the measured halo power spectrum in redshift space exhibits a large-scale enhancement in amplitude relative to the real-space clustering, and the effect becomes significant for the massive or highly biased halo samples. These findings cannot be simply explained by the so-called streaming model frequently used in the literature. By contrast, a physically motivated perturbation theory model developed in the previous paper reproduces the halo power spectrum very well, and the model combining a simple linear scale-dependent bias can accurately characterize the clustering anisotropies of halos in two dimensions, i.e., line-of-sight and its perpendicular directions. The results highlight the significance of nonlinear coupling between density and velocity fields associated with two competing effects of redshift distortions, i.e., Kaiser and Finger-of-God effects, and a proper account of this effect would be important in accurately characterizing the baryon acoustic oscillations in two dimensions.

Fluids and Combustion Facility Acoustic Emissions Controlled by Aggressive Low-Noise Design Process

NASA Technical Reports Server (NTRS)

Cooper, Beth A.; Young, Judith A.

2004-01-01

The Fluids and Combustion Facility (FCF) is a dual-rack microgravity research facility that is being developed by Northrop Grumman Information Technology (NGIT) for the International Space Station (ISS) at the NASA Glenn Research Center. As an on-orbit test bed, FCF will host a succession of experiments in fluid and combustion physics. The Fluids Integrated Rack (FIR) and the Combustion Integrated Rack (CIR) must meet ISS acoustic emission requirements (ref. 1), which support speech communication and hearing-loss-prevention goals for ISS crew. To meet these requirements, the NGIT acoustics team implemented an aggressive low-noise design effort that incorporated frequent acoustic emission testing for all internal noise sources, larger-scale systems, and fully integrated racks (ref. 2). Glenn's Acoustical Testing Laboratory (ref. 3) provided acoustical testing services (see the following photograph) as well as specialized acoustical engineering support as part of the low-noise design process (ref. 4).

Ares I Scale Model Acoustic Tests Instrumentation for Acoustic and Pressure Measurements

NASA Technical Reports Server (NTRS)

Vargas, Magda B.; Counter, Douglas D.

2011-01-01

The Ares I Scale Model Acoustic Test (ASMAT) was a development test performed at the Marshall Space Flight Center (MSFC) East Test Area (ETA) Test Stand 116. The test article included a 5% scale Ares I vehicle model and tower mounted on the Mobile Launcher. Acoustic and pressure data were measured by approximately 200 instruments located throughout the test article. There were four primary ASMAT instrument suites: ignition overpressure (IOP), lift-off acoustics (LOA), ground acoustics (GA), and spatial correlation (SC). Each instrumentation suite incorporated different sensor models which were selected based upon measurement requirements. These requirements included the type of measurement, exposure to the environment, instrumentation check-outs and data acquisition. The sensors were attached to the test article using different mounts and brackets dependent upon the location of the sensor. This presentation addresses the observed effect of the sensors and mounts on the acoustic and pressure measurements.

KENNEDY SPACE CENTER, FLA. - Researchers are positioned on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Researchers are positioned on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Dr. Grant Gilmore (left), Dynamac Corp., talks to another member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Dr. Grant Gilmore (left), Dynamac Corp., talks to another member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Joe Bartoszek, NASA, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Joe Bartoszek, NASA, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members take their places on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members take their places on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Dr. Grant Gilmore, Dynamac Corp., utilizes a laptop computer to explain aspects of the underwater acoustic research under way in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Dr. Grant Gilmore, Dynamac Corp., utilizes a laptop computer to explain aspects of the underwater acoustic research under way in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NFL Films music scoring stage and control room space

NASA Astrophysics Data System (ADS)

Berger, Russ; Schrag, Richard C.; Ridings, Jason J.

2003-04-01

NFL Films' new 200,000 sq. ft. corporate headquarters is home to an orchestral scoring stage used to record custom music scores to support and enhance their video productions. Part of the 90,000 sq. ft. of sound critical technical space, the music scoring stage and its associated control room are at the heart of the audio facilities. Driving the design were the owner's mandate for natural light, wood textures, and an acoustical environment that would support small rhythm sections, soloists, and a full orchestra. Being an industry leader in cutting-edge video and audio formats, the NFLF required that the technical spaces allow the latest in technology to be continually integrated into the infrastructure. Never was it more important for a project to hold true to the adage of ``designing from the inside out.'' Each audio and video space within the facility had to stand on its own with regard to user functionality, acoustical accuracy, sound isolation, noise control, and monitor presentation. A detailed look at the architectural and acoustical design challenges encountered and the solutions developed for the performance studio and the associated control room space will be discussed.

Subscale Acoustic Testing: Comparison of ALAT and ASMAT

NASA Technical Reports Server (NTRS)

Houston, Janice D.; Counter, Douglas

2014-01-01

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 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. This paper compares the acoustic measurements of two different subscale tests: the 2% Ares Liftoff Acoustic Test conducted at Stennis Space Center and the 5% Ares I Scale Model Acoustic Test conducted at Marshall Space Flight Center.

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.

Overview of the Ares I Scale Model Acoustic Test Program

NASA Technical Reports Server (NTRS)

Counter, Douglas D.; Houston, Janice D.

2011-01-01

Launch environments, such as lift-off acoustic (LOA) and ignition overpressure (IOP), are important design factors for any vehicle and are dependent upon the design of both the vehicle and the ground systems. LOA environments are used directly in the development of vehicle vibro-acoustic environments and IOP is used in the loads assessment. The NASA Constellation Program had several risks to the development of the Ares I vehicle linked to LOA. The risks included cost, schedule and technical impacts for component qualification due to high predicted vibro-acoustic environments. One solution is to mitigate the environment at the component level. However, where the environment is too severe for component survivability, reduction of the environment itself is required. The Ares I Scale Model Acoustic Test (ASMAT) program was implemented to verify the Ares I LOA and IOP environments for the vehicle and ground systems including the Mobile Launcher (ML) and tower. An additional objective was to determine the acoustic reduction for the LOA environment with an above deck water sound suppression system. ASMAT was a development test performed at the Marshall Space Flight Center (MSFC) East Test Area (ETA) Test Stand 116 (TS 116). The ASMAT program is described in this presentation.

Simulation of Shuttle launch G forces and acoustic loads using the NASA Ames Research Center 20G centrifuge

NASA Technical Reports Server (NTRS)

Shaw, T. L.; Corliss, J. M.; Gundo, D. P.; Mulenburg, G. M.; Breit, G. A.; Griffith, J. B.

1994-01-01

The high cost and long times required to develop research packages for space flight can often be offset by using ground test techniques. This paper describes a space shuttle launch and reentry simulating using the NASA Ames Research Center's 20G centrifuge facility. The combined G-forces and acoustic environment during shuttle launch and landing were simulated to evaluate the effect on a payload of laboratory rates. The launch G force and acoustic profiles are matched to actual shuttle launch data to produce the required G-forces and acoustic spectrum in the centrifuge test cab where the rats were caged on a free-swinging platform. For reentry, only G force is simulated as the aero-acoustic noise is insignificant compared to that during launch. The shuttle G-force profiles of launch and landing are achieved by programming the centrifuge drive computer to continuously adjust centrifuge rotational speed to obtain the correct launch and landing G forces. The shuttle launch acoustic environment is simulated using a high-power, low-frequency audio system. Accelerometer data from STS-56 and microphone data from STS-1 through STS-5 are used as baselines for the simulations. This paper provides a description of the test setup and the results of the simulation with recommendations for follow-on simulations.

The first radial-mode Lorentzian Landau damping of dust acoustic space-charge waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588

2016-05-15

The dispersion properties and the first radial-mode Lorentzian Landau damping of a dust acoustic space-charge wave propagating in a cylindrical waveguide dusty plasma which contains nonthermal electrons and ions are investigated by employing the normal mode analysis and the method of separation of variables. It is found that the frequency of dust acoustic space-charge wave increases as the wave number increases as well as the radius of cylindrical plasma does. However, the nonthermal property of the Lorentzian plasma is found to suppress the wave frequency of the dust acoustic space-charge wave. The Landau damping rate of the dust acoustic space-chargemore » wave is derived in a cylindrical waveguide dusty plasma. The damping of the space-charge wave is found to be enhanced as the radius of cylindrical plasma and the nonthermal property increase. The maximum Lorentzian Landau damping rate is also found in a cylindrical waveguide dusty plasma. The variation of the wave frequency and the Landau damping rate due to the nonthermal character and geometric effects are also discussed.« less

Acoustic vibration analysis for utilization of woody plant in space environment

NASA Astrophysics Data System (ADS)

Chida, Yukari; Yamashita, Masamichi; Hashimoto, Hirofumi; Sato, Seigo; Tomita-Yokotani, Kaori; Baba, Keiichi; Suzuki, Toshisada; Motohashi, Kyohei; Sakurai, Naoki; Nakagawa-izumi, Akiko

2012-07-01

We are proposing to raise woody plants for space agriculture in Mars. Space agriculture has the utilization of wood in their ecosystem. Nobody knows the real tree shape grown under space environment under the low or micro gravitational conditions such as outer environment. Angiosperm tree forms tension wood for keeping their shape. Tension wood formation is deeply related to gravity, but the details of the mechanism of its formation has not yet been clarified. For clarifying the mechanism, the space experiment in international space station, ISS is the best way to investigate about them as the first step. It is necessary to establish the easy method for crews who examine the experiments at ISS. Here, we are proposing to investigate the possibility of the acoustic vibration analysis for the experiment at ISS. Two types of Japanese cherry tree, weeping and upright types in Prunus sp., were analyzed by the acoustic vibration method. Coefficient-of-variation (CV) of sound speed was calculated by the acoustic vibration analysis. The amount of lignin and decomposed lignin were estimated by both Klason and Py-GC/MS method, respectively. The relationships of the results of acoustic vibration analysis and the inner components in tested woody materials were investigated. After the experiments, we confirm the correlation about them. Our results indicated that the acoustic vibration analysis would be useful for determining the inside composition as a nondestructive method in outer space environment.

Huygens-Fresnel Acoustic Interference and the Development of Robust Time-Averaged Patterns from Traveling Surface Acoustic Waves

NASA Astrophysics Data System (ADS)

Devendran, Citsabehsan; Collins, David J.; Ai, Ye; Neild, Adrian

2017-04-01

Periodic pattern generation using time-averaged acoustic forces conventionally requires the intersection of counterpropagating wave fields, where suspended micro-objects in a microfluidic system collect along force potential minimizing nodal or antinodal lines. Whereas this effect typically requires either multiple transducer elements or whole channel resonance, we report the generation of scalable periodic patterning positions without either of these conditions. A single propagating surface acoustic wave interacts with the proximal channel wall to produce a knife-edge effect according to the Huygens-Fresnel principle, where these cylindrically propagating waves interfere with classical wave fronts emanating from the substrate. We simulate these conditions and describe a model that accurately predicts the lateral spacing of these positions in a robust and novel approach to acoustic patterning.

Assessment of Microphone Phased Array for Measuring Launch Vehicle Lift-off Acoustics

NASA Technical Reports Server (NTRS)

Garcia, Roberto

2012-01-01

The specific purpose of the present work was to demonstrate the suitability of a microphone phased array for launch acoustics applications via participation in selected firings of the Ares I Scale Model Acoustics Test. The Ares I Scale Model Acoustics Test is a part of the discontinued Constellation Program Ares I Project, but the basic understanding gained from this test is expected to help development of the Space Launch System vehicles. Correct identification of sources not only improves the predictive ability, but provides guidance for a quieter design of the launch pad and optimization of the water suppression system. This document contains the results of the NASA Engineering and Safety Center assessment.

Measurement and Characterization of Space Shuttle Solid Rocket Motor Plume Acoustics

NASA Technical Reports Server (NTRS)

Kenny, Robert Jeremy

2009-01-01

NASA's current models to predict lift-off acoustics for launch vehicles are currently being updated using several numerical and empirical inputs. One empirical input comes from free-field acoustic data measured at three Space Shuttle Reusable Solid Rocket Motor (RSRM) static firings. The measurements were collected by a joint collaboration between NASA - Marshall Space Flight Center, Wyle Labs, and ATK Launch Systems. For the first time NASA measured large-thrust solid rocket motor plume acoustics for evaluation of both noise sources and acoustic radiation properties. Over sixty acoustic free-field measurements were taken over the three static firings to support evaluation of acoustic radiation near the rocket plume, far-field acoustic radiation patterns, plume acoustic power efficiencies, and apparent noise source locations within the plume. At approximately 67 m off nozzle centerline and 70 m downstream of the nozzle exit plan, the measured overall sound pressure level of the RSRM was 155 dB. Peak overall levels in the far field were over 140 dB at 300 m and 50-deg off of the RSRM thrust centerline. The successful collaboration has yielded valuable data that are being implemented into NASA's lift-off acoustic models, which will then be used to update predictions for Ares I and Ares V liftoff acoustic environments.

A Smart Sensor Web for Ocean Observation: Integrated Acoustics, Satellite Networking, and Predictive Modeling

NASA Astrophysics Data System (ADS)

Arabshahi, P.; Chao, Y.; Chien, S.; Gray, A.; Howe, B. M.; Roy, S.

2008-12-01

In many areas of Earth science, including climate change research, there is a need for near real-time integration of data from heterogeneous and spatially distributed sensors, in particular in-situ and space- based sensors. The data integration, as provided by a smart sensor web, enables numerous improvements, namely, 1) adaptive sampling for more efficient use of expensive space-based sensing assets, 2) higher fidelity information gathering from data sources through integration of complementary data sets, and 3) improved sensor calibration. The specific purpose of the smart sensor web development presented here is to provide for adaptive sampling and calibration of space-based data via in-situ data. Our ocean-observing smart sensor web presented herein is composed of both mobile and fixed underwater in-situ ocean sensing assets and Earth Observing System (EOS) satellite sensors providing larger-scale sensing. An acoustic communications network forms a critical link in the web between the in-situ and space-based sensors and facilitates adaptive sampling and calibration. After an overview of primary design challenges, we report on the development of various elements of the smart sensor web. These include (a) a cable-connected mooring system with a profiler under real-time control with inductive battery charging; (b) a glider with integrated acoustic communications and broadband receiving capability; (c) satellite sensor elements; (d) an integrated acoustic navigation and communication network; and (e) a predictive model via the Regional Ocean Modeling System (ROMS). Results from field experiments, including an upcoming one in Monterey Bay (October 2008) using live data from NASA's EO-1 mission in a semi closed-loop system, together with ocean models from ROMS, are described. Plans for future adaptive sampling demonstrations using the smart sensor web are also presented.

Acoustical consulting-Reflections on a challenging career

NASA Astrophysics Data System (ADS)

Braslau, David

2004-05-01

The acoustical consulting profession can be entered in a number of ways. The most direct approach is to obtain a degree in acoustics and join a large consulting firm immediately after graduation. Acoustical consulting can also be entered indirectly from various fields of engineering or physics which can provide a somewhat broader background. These disciplines might include, for example, structural engineering and structural dynamics, mechanics of materials, dynamic behavior of solids or geophysics. Acoustical consulting specialization can be very broad or very narrow as seen from the National Council of Acoustical Consultants capability listing. As an acoustical consultant, one must address a wide range of problems which provides both the challenges and joys of this profession. Technical capabilities and professional judgment are constantly developed from exposure to these problems and through interaction with other members of the profession. Selected case studies including sound isolation in buildings, noise and vibration from blasting, control of noise from environmental sources, acoustical design of classrooms and performing spaces, and product design demonstrate the variety of challenges faced by an acoustical consultant.

Science Enabled by Ocean Observatory Acoustics

NASA Astrophysics Data System (ADS)

Howe, B. M.; Lee, C.; Gobat, J.; Freitag, L.; Miller, J. H.; Committee, I.

2004-12-01

Ocean observatories have the potential to examine the physical, chemical, biological, and geological parameters and processes of the ocean at time and space scales previously unexplored. Acoustics provides an efficient and cost-effective means by which these parameters and processes can be measured and information can be communicated. Integrated acoustics systems providing navigation and communications for mobile platforms and conducting acoustical measurements in support of science objectives are critical and essential elements of the ocean observatories presently in the planning and implementation stages. The ORION Workshop (Puerto Rico, 4-8 January 2004) developed science themes that can be addressed utilizing ocean observatory infrastructure. The use of acoustics to sense the 3-d/volumetric ocean environment on all temporal and spatial scales was discussed in many ORION working groups. Science themes that are related to acoustics and measurements using acoustics are reviewed and tabulated, as are the related and sometimes competing requirements for passive listening, acoustic navigation and acoustic communication around observatories. Sound in the sea, brought from observatories to universities and schools via the internet, will also be a major education and outreach mechanism.

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin monitor some of the project's equipment just released into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin monitor some of the project's equipment just released into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Justin Manley, of the National Oceanic and Atmospheric Administration, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-18

KENNEDY SPACE CENTER, FLA. - Justin Manley, of the National Oceanic and Atmospheric Administration, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin retrieve some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin retrieve some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin lifts some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin lifts some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin releases some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin releases some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepare to release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepare to release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin secure some of the project's equipment back into the vessel. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin secure some of the project's equipment back into the vessel. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepares some of the project's equipment for placement in the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

NASA Image and Video Library

2003-08-19

KENNEDY SPACE CENTER, FLA. - A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepares some of the project's equipment for placement in the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

Vibrations and structureborne noise in space station

NASA Technical Reports Server (NTRS)

Vaicaitis, R.

1985-01-01

The related literature was reviewed and a preliminary analytical model was developed for simplified acoustic and structural geometries for pressurized and unpressurized space station modules. In addition to the analytical work, an experimental program on structureborne noise generation and transmission was started. A brief review of those accomplishments is given.

Space shuttle maneuvering engine reusable thrust chamber program. Task 11: Stability analyses and acoustic model testing data dump

NASA Technical Reports Server (NTRS)

Oberg, C. L.

1974-01-01

The combustion stability characteristics of engines applicable to the Space Shuttle Orbit Maneuvering System and the adequacy of acoustic cavities as a means of assuring stability in these engines were investigated. The study comprised full-scale stability rating tests, bench-scale acoustic model tests and analysis. Two series of stability rating tests were made. Acoustic model tests were made to determine the resonance characteristics and effects of acoustic cavities. Analytical studies were done to aid design of the cavity configurations to be tested and, also, to aid evaluation of the effectiveness of acoustic cavities from available test results.

Acoustic and electromagnetic wave interaction in the detection and identification of buried objects

NASA Astrophysics Data System (ADS)

Lawrence, Daniel Edward

2002-09-01

In order to facilitate the development of a hybrid acoustic and electromagnetic (EM) system for buried object detection, a number of analytical solutions and a novel numerical technique are developed to analyze the complex interaction between acoustic and EM scattering. The essence of the interaction lies in the fact that identifiable acoustic properties of an object, such as acoustic resonances, can be observed in the scattered EM Doppler spectrum. Using a perturbation approach, analytical solutions are derived for the EM scattering from infinitely long circular cylinders, both metallic and dielectric, under acoustic vibration in a homogeneous background medium. Results indicate that both the shape variation and dielectric constant contribute to the scattered EM Doppler spectrum. To model the effect of a cylinder beneath an acoustically excited half-space, a new analytical solution is presented for EM scattering from a cylinder beneath a slightly rough surface. The solution is achieved by using plane-wave expansion of the fields and an iterative technique to account for the multiple interactions between the cylinder and rough surface. Following a similar procedure, a novel solution for elastic-wave scattering from a solid cylinder embedded in a solid half-space is developed and used to calculate the surface displacement. Simulations indicate that only a finite range of spatial surface frequencies, corresponding to surface roughness on the order of the EM wavelength; affect the EM scattering from buried objects and suggest that object detection can be improved if the acoustic excitation induces surface roughness outside this range. To extend the study to non-canonical scenarios, a novel numerical approach is introduced in which time-varying impedance boundary conditions (IBCs) are used in conjunction with the method of moments (MoM) to model the EM scattering from vibrating metallic objects of arbitrary shape. It is shown that the standard IBC provides a first order solution for TM polarization, but a second order IBC is needed for TE polarization. The crucial factor in the calculation of the potentially small Doppler components is that the time-varying nature of the cylinder boundary, contained within the surface impedance expressions, can be isolated from the unperturbed terms in the scattered field.

NORSTAR Project: Norfolk public schools student team for acoustical research

NASA Technical Reports Server (NTRS)

Fortunato, Ronald C.

1987-01-01

Development of the NORSTAR (Norfolk Public Student Team for Acoustical Research) Project includes the definition, design, fabrication, testing, analysis, and publishing the results of an acoustical experiment. The student-run program is based on a space flight organization similar to the Viking Project. The experiment will measure the scattering transfer of momentum from a sound field to spheres in a liquid medium. It is hoped that the experimental results will shed light on a difficult physics problem - the difference in scattering cross section (the overall effect of the sound wave scattering) for solid spheres and hollow spheres of differing wall thicknesses.

Virtual environment display for a 3D audio room simulation

NASA Technical Reports Server (NTRS)

Chapin, William L.; Foster, Scott H.

1992-01-01

The development of a virtual environment simulation system integrating a 3D acoustic audio model with an immersive 3D visual scene is discussed. The system complements the acoustic model and is specified to: allow the listener to freely move about the space, a room of manipulable size, shape, and audio character, while interactively relocating the sound sources; reinforce the listener's feeling of telepresence in the acoustical environment with visual and proprioceptive sensations; enhance the audio with the graphic and interactive components, rather than overwhelm or reduce it; and serve as a research testbed and technology transfer demonstration. The hardware/software design of two demonstration systems, one installed and one portable, are discussed through the development of four iterative configurations.

Acoustic Parametric Array for Identifying Standoff Targets

NASA Astrophysics Data System (ADS)

Hinders, M. K.; Rudd, K. E.

2010-02-01

An integrated simulation method for investigating nonlinear sound beams and 3D acoustic scattering from any combination of complicated objects is presented. A standard finite-difference simulation method is used to model pulsed nonlinear sound propagation from a source to a scattering target via the KZK equation. Then, a parallel 3D acoustic simulation method based on the finite integration technique is used to model the acoustic wave interaction with the target. Any combination of objects and material layers can be placed into the 3D simulation space to study the resulting interaction. Several example simulations are presented to demonstrate the simulation method and 3D visualization techniques. The combined simulation method is validated by comparing experimental and simulation data and a demonstration of how this combined simulation method assisted in the development of a nonlinear acoustic concealed weapons detector is also presented.

Project Morpheus Main Engine Development and Preliminary Flight Testing

NASA Technical Reports Server (NTRS)

Morehead, Robert L.

2011-01-01

A LOX/Methane rocket engine was developed for a prototype terrestrial lander and then used to fly the lander at Johnson Space Center. The development path of this engine is outlined, including unique items such as variable acoustic damping and variable film cooling.

2003 NASA Seal/Secondary Air System Workshop. Volume 1

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M. (Editor); Hendricks, Robert C. (Editor)

2004-01-01

The following reports were included in the 2003 NASA Seal/Secondary Air System Workshop:Low Emissions Alternative Power (LEAP); Overview of NASA Glenn Seal Developments; NASA Ultra Efficient Engine Technology Project Overview; Development of Higher Temperature Abradable Seals for Industrial Gas Turbines; High Misalignment Carbon Seals for the Fan Drive Gear System Technologies; Compliant Foil Seal Investigations; Test Rig for Evaluating Active Turbine Blade Tip Clearance Control Concepts; Controls Considerations for Turbine Active Clearance Control; Non-Contacting Finger Seal Developments and Design Considerations; Effect of Flow-Induced Radial Load on Brush Seal/Rotor Contact Mechanics; Seal Developments at Flowserve Corporation; Investigations of High Pressure Acoustic Waves in Resonators With Seal-Like Features; Numerical Investigations of High Pressure Acoustic Waves in Resonators; Feltmetal Seal Material Through-Flow; "Bimodal" Nuclear Thermal Rocket (BNTR) Propulsion for Future Human Mars Exploration Missions; High Temperature Propulsion System Structural Seals for Future Space Launch Vehicles; Advanced Control Surface Seal Development for Future Space Vehicles; High Temperature Metallic Seal Development for Aero Propulsion and Gas Turbine Applications; and BrazeFoil Honeycomb.

Development of Eddy Current Techniques for the Detection of Cracking in Space Shuttle Primary Reaction Control Thrusters

NASA Technical Reports Server (NTRS)

Wincheski, Buzz A.; Simpson, John W.; Koshti, Ajay

2007-01-01

A recent identification of cracking in the Space Shuttle Primary Reaction Control System (PRCS) thrusters triggered an extensive nondestructive evaluation effort to develop techniques capable of identifying such damage on installed shuttle hardware. As a part of this effort, specially designed eddy current probes inserted into the acoustic cavity were explored for the detection of such flaws and for evaluation of the remaining material between the crack tip and acoustic cavity. The technique utilizes two orthogonal eddy current probes which are scanned under stepper motor control in the acoustic cavity to identify cracks hidden with as much as 0.060 remaining wall thickness to the cavity. As crack growth rates in this area have been determined to be very slow, such an inspection provides a large safety margin for continued operation of the critical shuttle hardware. Testing has been performed on thruster components with both actual and fabricated defects. This paper will review the design and performance of the developed eddy current inspection system. Detection of flaws as a function of remaining wall thickness will be presented along with the proposed system configuration for depot level or on-vehicle inspection capabilities.

Development of Eddy Current Technique for the Detection of Stress Corrosion Cracking in Space Shuttle Primary Reaction Control Thrusters

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Simpson, John; Koshti, Ajay

2006-01-01

A recent identification of stress corrosion cracking in the Space Shuttle Primary Reaction Control System (PRCS) thrusters triggered an extensive nondestructive evaluation effort to develop techniques capable of identifying such damage on installed shuttle hardware. As a part of this effort, specially designed eddy current probes inserted into the acoustic cavity were explored for the detection of such flaws and for evaluation of the remaining material between the crack tip and acoustic cavity. The technique utilizes two orthogonal eddy current probes which are scanned under stepper motor control in the acoustic cavity to identify cracks hidden with as much as 0.060 remaining wall thickness to the cavity. As crack growth rates in this area have been determined to be very slow, such an inspection provides a large safety margin for continued operation of the critical shuttle hardware. Testing has been performed on thruster components with both actual and fabricated defects. This paper will review the design and performance of the developed eddy current inspection system. Detection of flaws as a function of remaining wall thickness will be presented along with the proposed system configuration for depot level or on-vehicle inspection capabilities.

Modes of self-organization of diluted bubbly liquids in acoustic fields: One-dimensional theory.

PubMed

Gumerov, Nail A; Akhatov, Iskander S

2017-02-01

The paper is dedicated to mathematical modeling of self-organization of bubbly liquids in acoustic fields. A continuum model describing the two-way interaction of diluted polydisperse bubbly liquids and acoustic fields in weakly-nonlinear approximation is studied analytically and numerically in the one-dimensional case. It is shown that the regimes of self-organization of monodisperse bubbly liquids can be controlled by only a few dimensionless parameters. Two basic modes, clustering and propagating shock waves of void fraction (acoustically induced transparency), are identified and criteria for their realization in the space of parameters are proposed. A numerical method for solving of one-dimensional self-organization problems is developed. Computational results for mono- and polydisperse systems are discussed.

Consecutive Plate Acoustic Suppressor Apparatus and Methods

NASA Technical Reports Server (NTRS)

Doychak, Joseph (Inventor); Parrott, Tony L. (Inventor)

1993-01-01

An apparatus and method for suppressing acoustic noise utilizes consecutive plates, closely spaced to each other so as to exploit dissipation associated with sound propagation in narrow channels to optimize the acoustic resistance at a liner surface. The closely spaced plates can be utilized as high temperature structural materials for jet engines by constructing the plates from composite materials. Geometries of the plates, such as plate depth, shape, thickness, inter-plate spacing, arrangement, etc., can be selected to achieve bulk material-like behavior.

The Testing Behind The Test Facility: The Acoustic Design of the NASA Glenn Research Center's World-Class Reverberant Acoustic Test Facility

NASA Technical Reports Server (NTRS)

Hozman, Aron D.; Hughes, William O.; McNelis, Mark E.; McNelis, Anne M.

2011-01-01

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA's space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 cu ft in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world's known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada's acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, USA. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent on-going construction.

14 CFR 25.856 - Thermal/Acoustic insulation materials.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Thermal/Acoustic insulation materials. 25....856 Thermal/Acoustic insulation materials. (a) Thermal/acoustic insulation material installed in the.../acoustic insulation materials (including the means of fastening the materials to the fuselage) installed in...

A survey of acoustic conditions and noise levels in secondary school classrooms in England.

PubMed

Shield, Bridget; Conetta, Robert; Dockrell, Julie; Connolly, Daniel; Cox, Trevor; Mydlarz, Charles

2015-01-01

An acoustic survey of secondary schools in England has been undertaken. Room acoustic parameters and background noise levels were measured in 185 unoccupied spaces in 13 schools to provide information on the typical acoustic environment of secondary schools. The unoccupied acoustic and noise data were correlated with various physical characteristics of the spaces. Room height and the amount of glazing were related to the unoccupied reverberation time and therefore need to be controlled to reduce reverberation to suitable levels for teaching and learning. Further analysis of the unoccupied data showed that the introduction of legislation relating to school acoustics in England and Wales in 2003 approximately doubled the number of school spaces complying with current standards. Noise levels were also measured during 274 lessons to examine typical levels generated during teaching activities in secondary schools and to investigate the influence of acoustic design on working noise levels in the classroom. Comparison of unoccupied and occupied data showed that unoccupied acoustic conditions affect the noise levels occurring during lessons. They were also related to the time spent in disruption to the lessons (e.g., students talking or shouting) and so may also have an impact upon student behavior in the classroom.

Volume I. Percussion Sextet. (original Composition). Volume II. The Simulation of Acoustical Space by Means of Physical Modeling.

NASA Astrophysics Data System (ADS)

Manzara, Leonard Charles

1990-01-01

The dissertation is in two parts:. 1. Percussion Sextet. The Percussion Sextet is a one movement musical composition with a length of approximately fifteen minutes. It is for six instrumentalists, each on a number of percussion instruments. The overriding formal problem was to construct a coherent and compelling structure which fuses a diversity of musical materials and textures into a dramatic whole. Particularly important is the synthesis of opposing tendencies contained in stochastic and deterministic processes: global textures versus motivic detail, and randomness versus total control. Several compositional techniques are employed in the composition. These methods of composition will be aided, in part, by the use of artificial intelligence techniques programmed on a computer. Finally, the percussion ensemble is the ideal medium to realize the above processes since it encompasses a wide range of both pitched and unpitched timbres, and since a great variety of textures and densities can be created with a certain economy of means. 2. The simulation of acoustical space by means of physical modeling. This is a written report describing the research and development of a computer program which simulates the characteristics of acoustical space in two dimensions. With the computer program the user can simulate most conventional acoustical spaces, as well as those physically impossible to realize in the real world. The program simulates acoustical space by means of geometric modeling. This involves defining wall equations, phantom source points and wall diffusions, and then processing input files containing digital signals through the program, producing output files ready for digital to analog conversion. The user of the program is able to define wall locations and wall reflectivity and roughness characteristics, all of which can be changed over time. Sound source locations are also definable within the acoustical space and these locations can be changed independently at any rate of speed. The sounds themselves are generated from any external sound synthesis program or appropriate sampling system. Finally, listener location and orientation is also user definable and dynamic in nature. A Receive-ReBroadcast (RRB) model is used to play back the sound and is definable from two to eight channels of sound. (Abstract shortened with permission of author.).

Examination of the Structural Response of the Orion European Service Module to Reverberant and Direct Field Acoustic Testing

NASA Technical Reports Server (NTRS)

McNelis, Mark E.; Hughes, William O.; Larko, Jeffrey M.; Bittinger, Samantha A.; Le-Plenier, Cyprien; Fogt, Vincent A.; Ngan, Ivan; Thirkettle, Anthony C.; Skinner, Mitch; Larkin, Paul

2017-01-01

The NASA Orion Multi-Purpose Crew Vehicle (MPCV), comprised of the Service Module, the Crew Module, and the Launch Abort System, is the next generation human spacecraft designed and built for deep space exploration. Orion will launch on NASAs new heavy-lift rocket, the Space Launch System. The European Space Agency (ESA) is responsible for providing the propulsion sub-assembly of the Service Module to NASA, called the European Service Module (ESM). The ESM is being designed and built by Airbus Safran Launchers for ESA. Traditionally, NASA has utilized reverberant acoustic testing for qualification of spaceflight hardware. The ESM Structural Test Article (E-STA) was tested at the NASA Plum Brook Stations (PBS) Reverberant Acoustic Test Facility in April-May 2016. However, Orion is evaluating an alternative acoustic test method, using direct field acoustic excitation, for the MPCVs Service Module and Crew Module. Lockheed Martin is responsible for the Orion proof-of-concept direct field acoustic test program. The E-STA was exposed to direct field acoustic testing at NASA PBS in February 2017. This paper compares the dynamic response of the E-STA structure and its components to both the reverberant and direct field acoustic test excitations. Advantages and disadvantages of direct field acoustic test excitation method are discussed.

Efficient Processing of Acoustic Signals for High Rate Information Transmission over Sparse Underwater Channels

DTIC Science & Technology

2016-09-02

the fractionally-spaced channel estimators and the short feedforward equalizer filters . Receiver algorithm is applied to real data transmitted at 10...multichannel decision-feedback equalizer (DFE)[1]. This receiver consists of a bank of adaptive feedforwad filters , one per array element, followed by a...decision-feedback filter . It has been implemented in the prototype high-rate acoustic modem developed at the Woods Hole Oceanographic Institution, and

Acoustics

NASA Technical Reports Server (NTRS)

Goodman, Jerry R.; Grosveld, Ferdinand

2007-01-01

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

Space station interior noise analysis program

NASA Technical Reports Server (NTRS)

Stusnick, E.; Burn, M.

1987-01-01

Documentation is provided for a microcomputer program which was developed to evaluate the effect of the vibroacoustic environment on speech communication inside a space station. The program, entitled Space Station Interior Noise Analysis Program (SSINAP), combines a Statistical Energy Analysis (SEA) prediction of sound and vibration levels within the space station with a speech intelligibility model based on the Modulation Transfer Function and the Speech Transmission Index (MTF/STI). The SEA model provides an effective analysis tool for predicting the acoustic environment based on proposed space station design. The MTF/STI model provides a method for evaluating speech communication in the relatively reverberant and potentially noisy environments that are likely to occur in space stations. The combinations of these two models provides a powerful analysis tool for optimizing the acoustic design of space stations from the point of view of speech communications. The mathematical algorithms used in SSINAP are presented to implement the SEA and MTF/STI models. An appendix provides an explanation of the operation of the program along with details of the program structure and code.

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

NASA Astrophysics Data System (ADS)

Wingqvist, Gunilla

2011-06-01

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

AST Launch Vehicle Acoustics

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.

Upwelling regime off the Cabo Frio region in Brazil and impact on acoustic propagation.

PubMed

Calado, Leandro; Camargo Rodríguez, Orlando; Codato, Gabriel; Contrera Xavier, Fabio

2018-03-01

This work introduces a description of the complex upwelling regime off the Cabo Frio region in Brazil and shows that ocean modeling, based on the feature-oriented regional modeling system (FORMS) technique, can produce reliable predictions of sound speed fields for the corresponding shallow water environment. This work also shows, through the development of simulations, that the upwelling regime can be responsible for the creation of shadow coastal zones, in which the detection probability is too low for an acoustic source to be detected. The development of the FORMS technique and its validation with real data, for the particular region of coastal upwelling off Cabo Frio, reveals the possibility of a sustainable and reliable forecast system for the corresponding (variable in space and time) underwater acoustic environment.

26th Space Simulation Conference Proceedings. Environmental Testing: The Path Forward

NASA Technical Reports Server (NTRS)

Packard, Edward A.

2010-01-01

Topics covered include: A Multifunctional Space Environment Simulation Facility for Accelerated Spacecraft Materials Testing; Exposure of Spacecraft Surface Coatings in a Simulated GEO Radiation Environment; Gravity-Offloading System for Large-Displacement Ground Testing of Spacecraft Mechanisms; Microscopic Shutters Controlled by cRIO in Sounding Rocket; Application of a Physics-Based Stabilization Criterion to Flight System Thermal Testing; Upgrade of a Thermal Vacuum Chamber for 20 Kelvin Operations; A New Approach to Improve the Uniformity of Solar Simulator; A Perfect Space Simulation Storm; A Planetary Environmental Simulator/Test Facility; Collimation Mirror Segment Refurbishment inside ESA s Large Space; Space Simulation of the CBERS 3 and 4 Satellite Thermal Model in the New Brazilian 6x8m Thermal Vacuum Chamber; The Certification of Environmental Chambers for Testing Flight Hardware; Space Systems Environmental Test Facility Database (SSETFD), Website Development Status; Wallops Flight Facility: Current and Future Test Capabilities for Suborbital and Orbital Projects; Force Limited Vibration Testing of JWST NIRSpec Instrument Using Strain Gages; Investigation of Acoustic Field Uniformity in Direct Field Acoustic Testing; Recent Developments in Direct Field Acoustic Testing; Assembly, Integration and Test Centre in Malaysia: Integration between Building Construction Works and Equipment Installation; Complex Ground Support Equipment for Satellite Thermal Vacuum Test; Effect of Charging Electron Exposure on 1064nm Transmission through Bare Sapphire Optics and SiO2 over HfO2 AR-Coated Sapphire Optics; Environmental Testing Activities and Capabilities for Turkish Space Industry; Integrated Circuit Reliability Simulation in Space Environments; Micrometeoroid Impacts and Optical Scatter in Space Environment; Overcoming Unintended Consequences of Ambient Pressure Thermal Cycling Environmental Tests; Performance and Functionality Improvements to Next Generation Thermal Vacuum Control System; Robotic Lunar Lander Development Project: Three-Dimensional Dynamic Stability Testing and Analysis; Thermal Physical Properties of Thermal Coatings for Spacecraft in Wide Range of Environmental Conditions: Experimental and Theoretical Study; Molecular Contamination Generated in Thermal Vacuum Chambers; Preventing Cross Contamination of Hardware in Thermal Vacuum Chambers; Towards Validation of Particulate Transport Code; Updated Trends in Materials' Outgassing Technology; Electrical Power and Data Acquisition Setup for the CBER 3 and 4 Satellite TBT; Method of Obtaining High Resolution Intrinsic Wire Boom Damping Parameters for Multi-Body Dynamics Simulations; and Thermal Vacuum Testing with Scalable Software Developed In-House.

Modeling and analysis of secondary sources coupling for active sound field reduction in confined spaces

NASA Astrophysics Data System (ADS)

Montazeri, Allahyar; Taylor, C. James

2017-10-01

This article addresses the coupling of acoustic secondary sources in a confined space in a sound field reduction framework. By considering the coupling of sources in a rectangular enclosure, the set of coupled equations governing its acoustical behavior are solved. The model obtained in this way is used to analyze the behavior of multi-input multi-output (MIMO) active sound field control (ASC) systems, where the coupling of sources cannot be neglected. In particular, the article develops the analytical results to analyze the effect of coupling of an array of secondary sources on the sound pressure levels inside an enclosure, when an array of microphones is used to capture the acoustic characteristics of the enclosure. The results are supported by extensive numerical simulations showing how coupling of loudspeakers through acoustic modes of the enclosure will change the strength and hence the driving voltage signal applied to the secondary loudspeakers. The practical significance of this model is to provide a better insight on the performance of the sound reproduction/reduction systems in confined spaces when an array of loudspeakers and microphones are placed in a fraction of wavelength of the excitation signal to reduce/reproduce the sound field. This is of particular importance because the interaction of different sources affects their radiation impedance depending on the electromechanical properties of the loudspeakers.

LAD-C: A large area debris collector on the ISS

NASA Technical Reports Server (NTRS)

Liou, J.-C.; Giovane, F. J.; Corsaro, R. D.; Burchell, M. J.; Drolshagen, G.; Kawai, H.; Stansbery, E. G.; Tabata, M.; Westphal, A. J.; Yano, H.

2006-01-01

The Large Area Debris Collector (LAD-C) is a 10 sq m aerogel and acoustic sensor system under development by the U.S. Naval Research Laboratory (NRL) with main collaboration from the NASA Orbital Debris Program Office at Johnson Space Center, JAXA Institute of Space and Astronautical Science (ISAS), Chiba University (Japan), ESA Space Debris Office, University of California at Berkeley, and University of Kent at Canterbury (UK). The U.S. Department of Defense (DoD) Space Test Program (STP) has assumed the responsibility for having the system manifested and deployed on the International Space Station (ISS), and then having it retrieved and returned to Earth after one to two years. LAD-C will attempt to utilize the ISS as a scientific platform to characterize the near-Earth meteoroid and orbital debris environment in the size regime where little data exist. In addition to meteoroid and orbital debris sample return, the acoustic sensors will record impact time, location, signal strength, and acoustic waveform data of the largest collected samples. A good time-dependent meteoroid and orbital debris flux estimate can be derived. Analysis of the data will also enable potential source identification of some of the collected samples. This dynamical link can be combined with laboratory composition analysis of impact residuals extracted from aerogel to further our understanding of orbital debris population, and the sources of meteoroids, asteroids and comets.

The Testing Behind the Test Facility: the Acoustic Design of the NASA Glenn Research Center's World-Class Reverberant Acoustic Test Facility

NASA Technical Reports Server (NTRS)

Hughes, William O.; McNelis, Mark E.; Hozman, Aron D.; McNelis, Anne M.

2010-01-01

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC s Plum Brook Station in Sandusky, Ohio, U.S.A. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA s space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, U.S.A. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent ongoing construction.

The Testing Behind The Test Facility: The Acoustic Design of the NASA Glenn Research Center's World-Class Reverberant Acoustic Test Facility

NASA Technical Reports Server (NTRS)

Hughes, William O.; McNelis, Mark E.; McNelis, Anne M.

2011-01-01

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC?s Plum Brook Station in Sandusky, Ohio, USA. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA?s space exploration program. T he large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world?s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada?s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, USA. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic de-sign and subsequent on-going construction.

Three-dimensional broadband omnidirectional acoustic ground cloak

NASA Astrophysics Data System (ADS)

Zigoneanu, Lucian; Popa, Bogdan-Ioan; Cummer, Steven A.

2014-04-01

The control of sound propagation and reflection has always been the goal of engineers involved in the design of acoustic systems. A recent design approach based on coordinate transformations, which is applicable to many physical systems, together with the development of a new class of engineered materials called metamaterials, has opened the road to the unconstrained control of sound. However, the ideal material parameters prescribed by this methodology are complex and challenging to obtain experimentally, even using metamaterial design approaches. Not surprisingly, experimental demonstration of devices obtained using transformation acoustics is difficult, and has been implemented only in two-dimensional configurations. Here, we demonstrate the design and experimental characterization of an almost perfect three-dimensional, broadband, and, most importantly, omnidirectional acoustic device that renders a region of space three wavelengths in diameter invisible to sound.

International Space Station USOS Crew Quarters Ventilation and Acoustic Design Implementation

NASA Technical Reports Server (NTRS)

Broyan, James Lee, Jr.

2009-01-01

The International Space Station (ISS) United States Operational Segment (USOS) has four permanent rack sized ISS Crew Quarters (CQ) providing a private crewmember space. The CQ uses Node 2 cabin air for ventilation/thermal cooling, as opposed to conditioned ducted air from the ISS Temperature Humidity Control System or the ISS fluid cooling loop connections. Consequently, CQ can only increase the air flow rate to reduce the temperature delta between the cabin and the CQ interior. However, increasing airflow causes increased acoustic noise so efficient airflow distribution is an important design parameter. The CQ utilized a two fan push-pull configuration to ensure fresh air at the crewmember s head position and reduce acoustic exposure. The CQ interior needs to be below Noise Curve 40 (NC-40). The CQ ventilation ducts are open to the significantly louder Node 2 cabin aisle way which required significantly acoustic mitigation controls. The design implementation of the CQ ventilation system and acoustic mitigation are very inter-related and require consideration of crew comfort balanced with use of interior habitable volume, accommodation of fan failures, and possible crew uses that impact ventilation and acoustic performance. This paper illustrates the types of model analysis, assumptions, vehicle interactions, and trade-offs required for CQ ventilation and acoustics. Additionally, on-orbit ventilation system performance and initial crew feedback is presented. This approach is applicable to any private enclosed space that the crew will occupy.

Flow Interpretation Implications for Poro-Elastic Modeling

DTIC Science & Technology

2010-06-01

interpretation of acoustical inversions based on poro-elastic models . I. INTRODUCTION Poro-elastic models for acoustic propagation in sediments arose out of the...porous solid. ii. higher freqency range, J. Acoust . Soc. America, 28, 179– 191, 1956. [11] Bear, J., and Y. Bachmat (Eds.), Introduction to Modeling of...Flow interpretation implications for Poro-Elastic Modeling James K. Fulford Naval Research Laboratory Stennis Space Center Stennis Space Center

Ocean acoustic reverberation tomography.

PubMed

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.

Acoustic streaming in the cochlea under compressive bone conduction excitation

NASA Astrophysics Data System (ADS)

Aho, Katherine; Sunny, Megha; Nabat, Taoufik; Au, Jenny; Thompson, Charles

2012-02-01

This work examines the acoustic streaming in the cochlea. A model will be developed to examine the steady flow over a flexible boundary that is induced by compressive excitation of the cochlear capsule. A stokeslet based analysis of oscillatory flows was used to model fluid motion. The influence of evanescent modes on the pressure field is considered as the limit of the aspect ratio epsilon approaches zero. We will show a uniformly valid solution in space.

Development of the Space Debris Sensor (SDS)

NASA Technical Reports Server (NTRS)

Hamilton, Joe; Liou, J. -C.; Anz-Meador, P.; Matney, M.; Christiansen, E.

2017-01-01

Debris Resistive/Acoustic Grid Orbital Navy-NASA Sensor (DRAGONS) is an impact sensor designed to detect and characterize collisions with small orbital debris: from 50 microns to greater than 1millimeter debris size detection; Characterizes debris size, speed, direction, and density. The Space Debris Sensor (SDS) is a flight demonstration of DRAGONS on the International Space Station: Approximately 1 square meter of detection area facing the ISS velocity vector; Minimum two year mission on Columbus External Payloads Facility (EPF); Minimal obstruction from ISS hardware; Development is nearing final checkout and integration with the ISS; Current launch schedule is SpaceX13, about September 2017, or SpaceX14, about Jan 2018.

Hybrid CFD/CAA Modeling for Liftoff Acoustic Predictions

NASA Technical Reports Server (NTRS)

Strutzenberg, Louise L.; Liever, Peter A.

2011-01-01

This paper presents development efforts at the NASA Marshall Space flight Center to establish a hybrid Computational Fluid Dynamics and Computational Aero-Acoustics (CFD/CAA) simulation system for launch vehicle liftoff acoustics environment analysis. Acoustic prediction engineering tools based on empirical jet acoustic strength and directivity models or scaled historical measurements are of limited value in efforts to proactively design and optimize launch vehicles and launch facility configurations for liftoff acoustics. CFD based modeling approaches are now able to capture the important details of vehicle specific plume flow environment, identifY the noise generation sources, and allow assessment of the influence of launch pad geometric details and sound mitigation measures such as water injection. However, CFD methodologies are numerically too dissipative to accurately capture the propagation of the acoustic waves in the large CFD models. The hybrid CFD/CAA approach combines the high-fidelity CFD analysis capable of identifYing the acoustic sources with a fast and efficient Boundary Element Method (BEM) that accurately propagates the acoustic field from the source locations. The BEM approach was chosen for its ability to properly account for reflections and scattering of acoustic waves from launch pad structures. The paper will present an overview of the technology components of the CFD/CAA framework and discuss plans for demonstration and validation against test data.

Passive long range acousto-optic sensor

NASA Astrophysics Data System (ADS)

Slater, Dan

2006-08-01

Alexander Graham Bell's photophone of 1880 was a simple free space optical communication device that used the sun to illuminate a reflective acoustic diaphragm. A selenium photocell located 213 m (700 ft) away converted the acoustically modulated light beam back into sound. A variation of the photophone is presented here that uses naturally formed free space acousto-optic communications links to provide passive multichannel long range acoustic sensing. This system, called RAS (remote acoustic sensor), functions as a long range microphone with a demonstrated range in excess of 40 km (25 miles).

Rapid Speech Transmission Index predictions and auralizations of unusual instructional spaces at MIT's new Stata Center

NASA Astrophysics Data System (ADS)

Conant, David A.

2005-04-01

The Stata Center for Computer, Information and Intelligence Sciences, recently opened at the Massachusetts Institute of Technology, includes a variety of oddly-shaped seminar rooms in addition to lecture spaces of somewhat more conventional form. The architects design approach prohibited following conventional, well understood room-acoustical behavior yet MIT and the design team were keenly interested in ensuring that these spaces functioned exceptionally well, acoustically. CATT-Acoustic room modeling was employed to assess RASTI through multiple design iterations for all these spaces. Presented here are computational and descriptive results achieved for these rooms which are highly-regarded by faculty. They all sound peculiarly good, given their unusual form. In addition, binaural auralizations for selected spaces are provided.

KSC-03PD-2364

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Researchers conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

All-angle Negative Reflection with An Ultrathin Acoustic Gradient Metasurface: Floquet-Bloch Modes Perspective and Experimental Verification.

PubMed

Liu, Bingyi; Zhao, Jiajun; Xu, Xiaodong; Zhao, Wenyu; Jiang, Yongyuan

2017-10-23

Metasurface with gradient phase response offers new alternative for steering the propagation of waves. Conventional Snell's law has been revised by taking the contribution of local phase gradient into account. However, the requirement of momentum matching along the metasurface sets its nontrivial beam manipulation functionality within a limited-angle incidence. In this work, we theoretically and experimentally demonstrate that the acoustic gradient metasurface supports the negative reflection for all-angle incidence. The mode expansion theory is developed to help understand how the gradient metasurface tailors the incident beams, and the all-angle negative reflection occurs when the first negative order Floquet-Bloch mode dominates inside the metasurface slab. The coiling-up space structures are utilized to build desired acoustic gradient metasurface, and the all-angle negative reflections have been perfectly verified by experimental measurements. Our work offers the Floquet-Bloch modes perspective for qualitatively understanding the reflection behaviors of the acoustic gradient metasurface, and the all-angle negative reflection characteristic possessed by acoustic gradient metasurface could enable a new degree of the acoustic wave manipulating and be applied in the functional diffractive acoustic elements, such as the all-angle acoustic back reflector.

Acoustic Liquid Manipulation Used to Enhance Electrochemical Processes

NASA Technical Reports Server (NTRS)

Oeftering, Richard C.

2005-01-01

Working in concert with the NASA Technology Transfer and Partnership Office, the Great Lakes Industrial Technology Center, and Alchemitron Corporation of Elgin, Illinois, the NASA Glenn Research Center has applied nonlinear acoustic principles to industrial applications. High-intensity ultrasonic beam techniques employ the effects of acoustic radiation pressure and acoustic streaming to manipulate the behavior of liquids. This includes propelling liquids, moving bubbles, and ejecting liquids as droplets and fountains. Since these effects can be accomplished without mechanical pumps or moving parts, we are exploring how these techniques could be used to manipulate liquids in space applications. Some of these acoustic techniques could be used both in normal Earth gravity and in the microgravity of space.

Predicting double negativity using transmitted phase in space coiling metamaterials.

PubMed

Maurya, Santosh K; Pandey, Abhishek; Shukla, Shobha; Saxena, Sumit

2018-05-01

Metamaterials are engineered materials that offer the flexibility to manipulate the incident waves leading to exotic applications such as cloaking, extraordinary transmission, sub-wavelength imaging and negative refraction. These concepts have largely been explored in the context of electromagnetic waves. Acoustic metamaterials, similar to their optical counterparts, demonstrate anomalous effective elastic properties. Recent developments have shown that coiling up the propagation path of acoustic wave results in effective elastic response of the metamaterial beyond the natural response of its constituent materials. The effective response of metamaterials is generally evaluated using the 'S' parameter retrieval method based on amplitude of the waves. The phase of acoustic waves contains information of wave pressure and particle velocity. Here, we show using finite-element methods that phase reversal of transmitted waves may be used to predict extreme acoustic properties in space coiling metamaterials. This change is the difference in the phase of the transmitted wave with respect to the incident wave. This method is simpler when compared with the more rigorous 'S' parameter retrieval method. The inferences drawn using this method have been verified experimentally for labyrinthine metamaterials by showing negative refraction for the predicted band of frequencies.

International Space Station Crew Quarters Ventilation and Acoustic Design Implementation

NASA Technical Reports Server (NTRS)

Broyan, James L., Jr.; Cady, Scott M; Welsh, David A.

2010-01-01

The International Space Station (ISS) United States Operational Segment has four permanent rack sized ISS Crew Quarters (CQs) providing a private crew member space. The CQs use Node 2 cabin air for ventilation/thermal cooling, as opposed to conditioned ducted air-from the ISS Common Cabin Air Assembly (CCAA) or the ISS fluid cooling loop. Consequently, CQ can only increase the air flow rate to reduce the temperature delta between the cabin and the CQ interior. However, increasing airflow causes increased acoustic noise so efficient airflow distribution is an important design parameter. The CQ utilized a two fan push-pull configuration to ensure fresh air at the crew member's head position and reduce acoustic exposure. The CQ ventilation ducts are conduits to the louder Node 2 cabin aisle way which required significant acoustic mitigation controls. The CQ interior needs to be below noise criteria curve 40 (NC-40). The design implementation of the CQ ventilation system and acoustic mitigation are very inter-related and require consideration of crew comfort balanced with use of interior habitable volume, accommodation of fan failures, and possible crew uses that impact ventilation and acoustic performance. Each CQ required 13% of its total volume and approximately 6% of its total mass to reduce acoustic noise. This paper illustrates the types of model analysis, assumptions, vehicle interactions, and trade-offs required for CQ ventilation and acoustics. Additionally, on-orbit ventilation system performance and initial crew feedback is presented. This approach is applicable to any private enclosed space that the crew will occupy.

Implementation and Testing of the JANUS Standard with SSC Pacific’s Software-Defined Acoustic Modem

DTIC Science & Technology

2017-10-01

Communications Outpost (FDECO) Innovative Naval Prototype (INP) Program by the Advanced Photonic Technologies Branch (Code 55360), Space and Naval Warfare...underwater acoustic communication operations with NATO and non-NATO military and civilian maritime assets. iv ACRONYMS SPAWAR Space and Naval Warfare...the center frequency [1]. The ease of implementation and proven robustness in harsh underwater acoustic communication channels paved the way for

Vehicle Based Vector Sensor

DTIC Science & Technology

2015-09-28

buoyant underwater vehicle with an interior space in which a length of said underwater vehicle is equal to one tenth of the acoustic wavelength...underwater vehicle with an interior space in which a length of said underwater vehicle is equal to one tenth of the acoustic wavelength; an...unmanned underwater vehicle that can function as an acoustic vector sensor. (2) Description of the Prior Art [0004] It is known that a propagating

Near-resonance scattering from arrays of artificial fish swimbladders.

PubMed

Nero, R W; Feuillade, C; Thompson, C H; Love, R H

2007-01-01

The air-filled swimbladders of fish resonate like damped air bubbles, and are very efficient acoustic scatterers at low to mid frequencies (typically <20 kHz). Scattering experiments were performed on an artificial "fish school" constructed from polyethylene bubbles. A mathematical model, developed to describe near-resonance backscattering from schooling fish [J. Acoust. Soc. Am. 99, 196-208 (1996)], was used to analyze the physical behavior for three different arrays of these bubbles. The measurements gave excellent agreement with the model, showing that coupled-resonance and interference effects cause the frequency response of tightly packed arrays, with spacing corresponding to the order of a body length for fish, to differ significantly from those of more dispersed arrays. As the array spacing is increased to the equivalent of several body lengths, these effects rapidly diminish. The results of this comparison demonstrate that, at low to mid frequencies, coupled resonance and interference effects are likely in schooling fish, and need to be considered in applications of underwater acoustic methods to the study of fish populations.

Characterization of space dust using acoustic impact detection.

PubMed

Corsaro, Robert D; Giovane, Frank; Liou, Jer-Chyi; Burchell, Mark J; Cole, Michael J; Williams, Earl G; Lagakos, Nicholas; Sadilek, Albert; Anderson, Christopher R

2016-08-01

This paper describes studies leading to the development of an acoustic instrument for measuring properties of micrometeoroids and other dust particles in space. The instrument uses a pair of easily penetrated membranes separated by a known distance. Sensors located on these films detect the transient acoustic signals produced by particle impacts. The arrival times of these signals at the sensor locations are used in a simple multilateration calculation to measure the impact coordinates on each film. Particle direction and speed are found using these impact coordinates and the known membrane separations. This ability to determine particle speed, direction, and time of impact provides the information needed to assign the particle's orbit and identify its likely origin. In many cases additional particle properties can be estimated from the signal amplitudes, including approximate diameter and (for small particles) some indication of composition/morphology. Two versions of this instrument were evaluated in this study. Fiber optic displacement sensors are found advantageous when very thin membranes can be maintained in tension (solar sails, lunar surface). Piezoelectric strain sensors are preferred for thicker films without tension (long duration free flyers). The latter was selected for an upcoming installation on the International Space Station.

The Development of a Web-Based Urban Soundscape Evaluation System

NASA Astrophysics Data System (ADS)

Sudarsono, A. S.; Sarwono, J.

2018-05-01

Acoustic quality is one of the important aspects of urban design. It is usually evaluated based on how loud the urban environment is. However, this approach does not consider people’s perception of the urban acoustic environment. Therefore, a different method has been developed based on the perception of the acoustic environment using the concept of soundscape. Soundscape is defined as the acoustic environment perceived by people who are part of the environment. This approach considers the relationship between the sound source, the environment, and the people. The analysis of soundscape considers many aspects such as cultural aspects, people’s expectations, people’s experience of space, and social aspects. Soundscape affects many aspects of human life such as culture, health, and the quality of life. Urban soundscape management and planning must be integrated with the other aspect of urban design, both in the design and the improvement stages. The soundscape concept seeks to make the acoustic environment as pleasant as possible in a space with or without uncomfortable sound sources. Soundscape planning includes the design of physical features to achieve a positive perceptual outcome. It is vital to gather data regarding the relationship between humans and the components of a soundscape, e.g., sound sources, features of the physical environment, the functions of a space, and the expectation of the sound source. The data can be measured and gathered using several soundscape evaluation methods. Soundscape evaluation is usually conducted using in-situ surveys and laboratory experiments using a multi-speaker system. Although these methods have been validated and are widely used in soundscape analysis, there are some limitations in the application. The in-situ survey needs to be done at one time with many people at the same time because it is hard to replicate the acoustic environment. Conversely, the laboratory experiment does not have a problem with the repetition of the experiment. This method requires a room with a multi-speaker reproduction system. This project used a different method to analyse soundscape developed using headphones via the internet. The internet system for data gathering has been established; a website has enabled to reproduce high-quality audio and it has a system to design online questionnaires. Furthermore, the development of a virtual reality system allows the reproduction of virtual audio-visual stimulus on a website. Although the website has an established system to gather the required data, the problem is the validation of the reproduction system for soundscape analysis, which needs to be done with consideration of several factors: the suitable recording system, the effect of headphone variation, the calibration of the system, and the perception result from internet-based acoustic environment reproduction. This study aims to develop and validate a web-based urban soundscape evaluation method. By using this method, the experiment can be repeated easily and data can be gathered from many respondents. Furthermore, the simplicity of the system allows for the application by the stakeholders in urban design. The data gathered from this system is important for the design of an urban area with consideration of the acoustic aspects.

Space processing of chalcogenide glass

NASA Technical Reports Server (NTRS)

Larsen, D. C.; Ali, M. I.

1977-01-01

The manner in which the weightless, containerless nature of in-space processing can be successfully utilized to improve the quality of infrared transmitting chalcogenide glasses is determined. The technique of space processing chalcogenide glass was developed, and the process and equipment necessary to do so was defined. Earthbound processing experiments with As2S3 and G28Sb12Se60 glasses were experimented with. Incorporated into these experiments is the use of an acoustic levitation device.

Sound in ecclesiastical spaces in Cordoba. Architectural projects incorporating acoustic methodology (El sonido del espacio eclesial en Cordoba. El proyecto arquitectonico como procedimiento acustico)

NASA Astrophysics Data System (ADS)

Suarez, Rafael

2003-11-01

This thesis is concerned with the acoustic analysis of ecclesiastical spaces, and the subsequent implementation of acoustic design methodology in architectural renovations. One begins with an adequate architectural design of specific elements (shape, materials, and textures), with the intention of elimination of acoustic deficiencies that are common in such spaces. These are those deficiencies that impair good speech intelligibility and good musical audibility. The investigation is limited to churches in the province of Cordoba and to churches built after the reconquest of Spain (1236) and up until the 18th century. Selected churches are those that have undergone architectural renovations to adapt them to new uses or to make them more suitable for liturgical use. The thesis attempts to summarize the acoustic analyses and the acoustical solutions that have been implemented. The results are presented in a manner that should be useful for the adoption of a model for the functional renovation of ecclesiastical spaces. Such would allow those involved in architectural projects to specify the nature of the sound, even though somewhat intangible, within the ecclesiastical space. Thesis advisors: Jaime Navarro and Juan J. Sendra Copies of this thesis written in Spanish may be obtained by contacting the advisor, Jaime Navarro, E.T.S. de Arquitectura de Sevilla, Dpto. de Construcciones Arquitectonicas I, Av. Reina Mercedes, 2, 41012 Sevilla, Spain. E-mail address: jnavarro@us.es

Acoustic filtration and sedimentation of soot particles

NASA Astrophysics Data System (ADS)

Martin, K. M.; Ezekoye, O. A.

Removal of soot particles from a static chamber by an intense acoustic field is investigated. Combustion of a solid fuel fills a rectangular chamber with small soot particles, which sediment very slowly. The chamber is then irradiated by an intense acoustic source to produce a three dimensional standing wave field in the chamber. The acoustic excitation causes the soot particles to agglomerate, forming larger particles which sediment faster from the system. The soot also forms 1-2 cm disks, with axes parallel to the axis of the acoustic source, which are levitated by the sound field at half-wavelength spacing within the chamber. Laser extinction measurements are made to determine soot volume fractions as a function of exposure time within the chamber. The volume fraction is reduced over time by sedimentation and by particle migration to the disks. The soot disks are considered to be a novel mechanism for particle removal from the air stream, and this mechanism has been dubbed acoustic filtration. An experimental method is developed for comparing the rate of soot removal by sedimentation alone with the rate of soot removal by sedimentation and acoustic filtration. Results show that acoustic filtration increases the rate of soot removal by a factor of two over acoustically-induced sedimentation alone.

Periodic Time-Domain Nonlocal Nonreflecting Boundary Conditions for Duct Acoustics

NASA Technical Reports Server (NTRS)

Watson, Willie R.; Zorumski, William E.

1996-01-01

Periodic time-domain boundary conditions are formulated for direct numerical simulation of acoustic waves in ducts without flow. Well-developed frequency-domain boundary conditions are transformed into the time domain. The formulation is presented here in one space dimension and time; however, this formulation has an advantage in that its extension to variable-area, higher dimensional, and acoustically treated ducts is rigorous and straightforward. The boundary condition simulates a nonreflecting wave field in an infinite uniform duct and is implemented by impulse-response operators that are applied at the boundary of the computational domain. These operators are generated by convolution integrals of the corresponding frequency-domain operators. The acoustic solution is obtained by advancing the Euler equations to a periodic state with the MacCormack scheme. The MacCormack scheme utilizes the boundary condition to limit the computational space and preserve the radiation boundary condition. The success of the boundary condition is attributed to the fact that it is nonreflecting to periodic acoustic waves. In addition, transient waves can pass rapidly out of the solution domain. The boundary condition is tested for a pure tone and a multitone source in a linear setting. The effects of various initial conditions are assessed. Computational solutions with the boundary condition are consistent with the known solutions for nonreflecting wave fields in an infinite uniform duct.

Energy Efficient Engine acoustic supporting technology report

NASA Technical Reports Server (NTRS)

Lavin, S. P.; Ho, P. Y.

1985-01-01

The acoustic development of the Energy Efficient Engine combined testing and analysis using scale model rigs and an integrated Core/Low Spool demonstration engine. The scale model tests show that a cut-on blade/vane ratio fan with a large spacing (S/C = 2.3) is as quiet as a cut-off blade/vane ratio with a tighter spacing (S/C = 1.27). Scale model mixer tests show that separate flow nozzles are the noisiest, conic nozzles the quietest, with forced mixers in between. Based on projections of ICLS data the Energy Efficient Engine (E3) has FAR 36 margins of 3.7 EPNdB at approach, 4.5 EPNdB at full power takeoff, and 7.2 EPNdB at sideline conditions.

Exploration of the Maximum Entropy/Optimal Projection Approach to Control Design Synthesis for Large Space Structures.

DTIC Science & Technology

1985-02-01

Energy Analysis , a branch of dynamic modal analysis developed for analyzing acoustic vibration problems, its present stage of development embodies a...Maximum Entropy Stochastic Modelling and Reduced-Order Design Synthesis is a rigorous new approach to this class of problems. Inspired by Statistical

Unidirectional Wave Vector Manipulation in Two-Dimensional Space with an All Passive Acoustic Parity-Time-Symmetric Metamaterials Crystal

NASA Astrophysics Data System (ADS)

Liu, Tuo; Zhu, Xuefeng; Chen, Fei; Liang, Shanjun; Zhu, Jie

2018-03-01

Exploring the concept of non-Hermitian Hamiltonians respecting parity-time symmetry with classical wave systems is of great interest as it enables the experimental investigation of parity-time-symmetric systems through the quantum-classical analogue. Here, we demonstrate unidirectional wave vector manipulation in two-dimensional space, with an all passive acoustic parity-time-symmetric metamaterials crystal. The metamaterials crystal is constructed through interleaving groove- and holey-structured acoustic metamaterials to provide an intrinsic parity-time-symmetric potential that is two-dimensionally extended and curved, which allows the flexible manipulation of unpaired wave vectors. At the transition point from the unbroken to broken parity-time symmetry phase, the unidirectional sound focusing effect (along with reflectionless acoustic transparency in the opposite direction) is experimentally realized over the spectrum. This demonstration confirms the capability of passive acoustic systems to carry the experimental studies on general parity-time symmetry physics and further reveals the unique functionalities enabled by the judiciously tailored unidirectional wave vectors in space.

Comparative evaluation of Space Transportation System (STS)-3 flight and acoustic test random vibration response of the OSS-1 payload

NASA Technical Reports Server (NTRS)

On, F. J.

1983-01-01

A comparative evaluation of the Space Transportation System (STS)-3 flight and acoustic test random vibration response of the Office of Space Science-1 (OSS-1) payload is presented. The results provide insight into the characteristics of vibroacoustic response of pallet payload components in the payload bay during STS flights.

International Space Station USOS Crew Quarters Development

NASA Technical Reports Server (NTRS)

Broyan, James Lee, Jr.; Borrego, Melissa Ann; Bahr, Juergen F.

2008-01-01

The International Space Station (ISS) United States Operational Segment (USOS) currently provides a Temporary Sleep Station (TeSS) as crew quarters for one crewmember in the Laboratory Module. The Russian Segment provides permanent crew quarters (Kayutas) for two crewmembers in the Service Module. The TeSS provides limited electrical, communication, and ventilation functionality. A new permanent rack sized USOS ISS Crew Quarters (CQ) is being developed. Up to four CQs can be installed into the Node 2 element to increase the ISS crewmember size to six. The new CQs will provide private crewmember space with enhanced acoustic noise mitigation, integrated radiation reduction material, controllable airflow, communication equipment, redundant electrical systems, and redundant caution and warning systems. The rack sized CQ is a system with multiple crewmember restraints, adjustable lighting, controllable ventilation, and interfaces that allow each crewmember to personalize their CQ workspace. Providing an acoustically quiet and visually isolated environment, while ensuring crewmember safety, is critical for obtaining crewmember rest and comfort to enable long term crewmember performance. The numerous human factor, engineering, and program considerations during the concept, design, and prototyping are outlined in the paper.

Acoustic levitation technique for containerless processing at high temperatures in space

NASA Technical Reports Server (NTRS)

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

1988-01-01

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

Developments in the Implementation of Acoustic Droplet Ejection for Protein Crystallography.

PubMed

Wu, Ping; Noland, Cameron; Ultsch, Mark; Edwards, Bonnie; Harris, David; Mayer, Robert; Harris, Seth F

2016-02-01

Acoustic droplet ejection (ADE) enables crystallization experiments at the low-nanoliter scale, resulting in rapid vapor diffusion equilibration dynamics and efficient reagent usage in the empirical discovery of structure-enabling protein crystallization conditions. We extend our validation of this technology applied to the diverse physicochemical property space of aqueous crystallization reagents where dynamic fluid analysis coupled to ADE aids in accurate and precise dispensations. Addition of crystallization seed stocks, chemical additives, or small-molecule ligands effectively modulates crystallization, and we here provide examples in optimization of crystal morphology and diffraction quality by the acoustic delivery of ultra-small volumes of these cofactors. Additional applications are discussed, including set up of in situ proteolysis and alternate geometries of crystallization that leverage the small scale afforded by acoustic delivery. Finally, we describe parameters of a system of automation in which the acoustic liquid handler is integrated with a robotic arm, plate centrifuge, peeler, sealer, and stacks, which allows unattended high-throughput crystallization experimentation. © 2015 Society for Laboratory Automation and Screening.

Acoustical levitation for space processing. [weightless molten material manipulation

NASA Technical Reports Server (NTRS)

Wang, T. G.; Saffren, M. M.; Elleman, D. D.

1974-01-01

It is pointed out that many space-manufacturing processes will require the manipulation of weightless molten material within a container in such a way that the material does not touch the container wall. A description is given of an acoustical method which can be used for the positioning and shaping of any molten material including nonconductors such as glasses. The new approach makes use of an acoustical standing wave which is excited within an enclosure or resonator.

Various applications of Active Field Control (AFC)

NASA Astrophysics Data System (ADS)

Watanabe, Takayuki; Miyazaki, Hideo; Kishinaga, Shinji; Kawakami, Fukushi

2003-10-01

AFC is an electro-acoustic enhancement system, which has been under development at Yamaha Corporation. In this paper, several types of various AFC applications are discussed, while referring to representative projects for each application in Japan. (1) Realization of acoustics in a huge hall to classical music program, e.g., Tokyo International Forum. This venue is a multipurpose hall with approximately 5000 seats. AFC achieves loudness and reverberance equivalent to those of a hall with 2500 seats or fewer. (2) Optimization of acoustics for a variety of programs, e.g., Arkas Sasebo. AFC is used to create the optimum acoustics for each program, such as reverberance for classical concerts, acoustical support for opera singers, uniformity throughout the hall from the stage to under-balcony area, etc. (3) Control of room shape acoustical effect, e.g., Osaka Central Public Hall: In this renovation project, preservation of historically important architecture in the original form is required. AFC is installed to vary only the acoustical environment without architectural changes. (4) Assistance with crowd enthusiasm for sports entertainment, e.g., Tokyo Metropolitan Gymnasium. In this venue, which is designed as a very absorptive space for speech intelligibility, AFC is installed to enhance the atmosphere of live sports entertainment.

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.

KSC-03PD-2379

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Researchers are positioned on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2365

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2376

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Researchers are positioned on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2366

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

Self-motion facilitates echo-acoustic orientation in humans

PubMed Central

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

NASA Applications of Structural Health Monitoring Technology

NASA Technical Reports Server (NTRS)

Richards, W Lance; Madaras, Eric I.; Prosser, William H.; Studor, George

2013-01-01

This presentation provides examples of research and development that has recently or is currently being conducted at NASA, with a special emphasis on the application of structural health monitoring (SHM) of aerospace vehicles. SHM applications on several vehicle programs are highlighted, including Space Shuttle Orbiter, International Space Station, Uninhabited Aerial Vehicles, and Expandable Launch Vehicles. Examples of current and previous work are presented in the following categories: acoustic emission impact detection, multi-parameter fiber optic strain-based sensing, wireless sensor system development, and distributed leak detection.

NASA Applications of Structural Health Monitoring Technology

NASA Technical Reports Server (NTRS)

Richards, W Lance; Madaras, Eric I.; Prosser, William H.; Studor, George

2013-01-01

This presentation provides examples of research and development that has recently or is currently being conducted at NASA, with a special emphasis on the application of structural health monitoring (SHM) of aerospace vehicles. SHM applications on several vehicle programs are highlighted, including Space Shuttle Orbiter, the International Space Station, Uninhabited Aerial Vehicles, and Expendable Launch Vehicles. Examples of current and previous work are presented in the following categories: acoustic emission impact detection, multi-parameter fiber optic strain-based sensing, wireless sensor system development, and distributed leak detection.

Characterizing the audibility of sound field with diffusion in architectural spaces

NASA Astrophysics Data System (ADS)

Utami, Sentagi Sesotya

The significance of diffusion control in room acoustics is that it attempts to avoid echoes by dispersing reflections while removing less valuable sound energy. Some applications place emphasis on the enhancement of late reflections to promote a sense of envelopment, and on methods required to measure the performance of diffusers. What still remains unclear is the impact of diffusion on the audibility quality due to the geometric arrangement of architectural elements. The objective of this research is to characterize the audibility of the sound field with diffusion in architectural space. In order to address this objective, an approach utilizing various methods and new techniques relevant to room acoustics standards was applied. An array of microphones based on beam forming (i.e., an acoustic camera) was utilized for field measurements in a recording studio, classrooms, auditoriums, concert halls and sport arenas. Given the ability to combine a visual image with acoustical data, the impulse responses measured were analyzed to identify the impact of diffusive surfaces on the early, late, and reverberant sound fields. The effects of the room geometry and the proportions of the diffusive and absorptive surfaces were observed by utilizing geometrical room acoustics simulations. The degree of diffuseness in each space was measured by coherences from different measurement positions along with the acoustical conditions predicted by well-known objective parameters such as T30, EDT, C80, and C50. Noticeable differences of the auditory experience were investigated by utilizing computer-based survey techniques, including the use of an immersive virtual environment system, given the current software auralization capabilities. The results based on statistical analysis demonstrate the users' ability to localize the sound and to distinguish the intensity, clarity, and reverberation created within the virtual environment. Impact of architectural elements in diffusion control is evaluated by the design variable interaction, objectively and subjectively. Effectiveness of the diffusive surfaces is determined by the echo reduction and the sense of complete immersion in a given room acoustics volume. Application of such methodology at various stages of design provides the ability to create a better auditory experience by the users. The results based on the cases studied have contributed to the development of new acoustical treatment based on the diffusion characteristics.

Numerical Models for Sound Propagation in Long Spaces

NASA Astrophysics Data System (ADS)

Lai, Chenly Yuen Cheung

Both reverberation time and steady-state sound field are the key elements for assessing the acoustic condition in an enclosed space. They affect the noise propagation, speech intelligibility, clarity index, and definition. Since the sound field in a long space is non diffuse, classical room acoustics theory does not apply in this situation. The ray tracing technique and the image source methods are two common models to fathom both reverberation time and steady-state sound field in long enclosures nowadays. Although both models can give an accurate estimate of reverberation times and steady-state sound field directly or indirectly, they often involve time-consuming calculations. In order to simplify the acoustic consideration, a theoretical formulation has been developed for predicting both steady-state sound fields and reverberation times in street canyons. The prediction model is further developed to predict the steady-state sound field in a long enclosure. Apart from the straight long enclosure, there are other variations such as a cross junction, a long enclosure with a T-intersection, an U-turn long enclosure. In the present study, an theoretical and experimental investigations were conducted to develop formulae for predicting reverberation times and steady-state sound fields in a junction of a street canyon and in a long enclosure with T-intersection. The theoretical models are validated by comparing the numerical predictions with published experimental results. The theoretical results are also compared with precise indoor measurements and large-scale outdoor experimental results. In all of previous acoustical studies related to long enclosure, most of the studies are focused on the monopole sound source. Besides non-directional noise source, many noise sources in long enclosure are dipole like, such as train noise and fan noise. In order to study the characteristics of directional noise sources, a review of available dipole source was conducted. A dipole was constructed which was subsequent used for experimental studies. In additional, a theoretical model was developed for predicting dipole sound fields. The theoretical model can be used to study the effect of a dipole source on the speech intelligibility in long enclosures.

Correlation Results for a Mass Loaded Vehicle Panel Test Article Finite Element Models and Modal Survey Tests

NASA Technical Reports Server (NTRS)

Maasha, Rumaasha; Towner, Robert L.

2012-01-01

High-fidelity Finite Element Models (FEMs) were developed to support a recent test program at Marshall Space Flight Center (MSFC). The FEMs correspond to test articles used for a series of acoustic tests. Modal survey tests were used to validate the FEMs for five acoustic tests (a bare panel and four different mass-loaded panel configurations). An additional modal survey test was performed on the empty test fixture (orthogrid panel mounting fixture, between the reverb and anechoic chambers). Modal survey tests were used to test-validate the dynamic characteristics of FEMs used for acoustic test excitation. Modal survey testing and subsequent model correlation has validated the natural frequencies and mode shapes of the FEMs. The modal survey test results provide a basis for the analysis models used for acoustic loading response test and analysis comparisons

Effect of acoustic coupling on power-law flame acceleration in spherical confinement

NASA Astrophysics Data System (ADS)

Akkerman, V'yacheslav; Law, Chung K.

2013-01-01

A model describing acoustically-generated parametric instability in a spherical chamber is developed for quasi-one-dimensional, low-Mach number flames. We demonstrate how sound waves generated by a centrally-ignited, outwardly-propagating accelerating flamefront can be incorporated into an existing theory of self-similar flame acceleration in free space [V. Akkerman, C. K. Law, and V. Bychkov, "Self-similar accelerative propagation of expanding wrinkled flames and explosion triggering," Phys. Rev. E 83, 026305 (2011)], 10.1103/PhysRevE.83.026305. Being reflected from the chamber wall, flame-generated acoustics interact with the flamefront and the attendant hydrodynamic flamefront cellular instability. This in turn affects the subsequent flame morphology and propagation speed. It is shown that the acoustics modify the power-law flame acceleration, concomitantly facilitating or inhibiting the transition to detonation in confinement, which allows reconciliation of a discrepancy in experimental measurements of different groups.

Measured wavenumber: frequency spectrum associated with acoustic and aerodynamic wall pressure fluctuations.

PubMed

Arguillat, Blandine; Ricot, Denis; Bailly, Christophe; Robert, Gilles

2010-10-01

Direct measurements of the wavenumber-frequency spectrum of wall pressure fluctuations beneath a turbulent plane channel flow have been performed in an anechoic wind tunnel. A rotative array has been designed that allows the measurement of a complete map, 63×63 measuring points, of cross-power spectral densities over a large area. An original post-processing has been developed to separate the acoustic and the aerodynamic exciting loadings by transforming space-frequency data into wavenumber-frequency spectra. The acoustic part has also been estimated from a simple Corcos-like model including the contribution of a diffuse sound field. The measured acoustic contribution to the surface pressure fluctuations is 5% of the measured aerodynamic surface pressure fluctuations for a velocity and boundary layer thickness relevant for automotive interior noise applications. This shows that for aerodynamically induced car interior noise, both contributions to the surface pressure fluctuations on car windows have to be taken into account.

Noise transmission from a curved panel into a cylindrical enclosure: analysis of structural acoustic coupling.

PubMed

Henry, J K; Clark, R L

2001-04-01

Much of the research on sound transmission through the aircraft fuselage into the interior of aircraft has considered coupling of the entire cylinder to the acoustic modes of the enclosure. Yet, much of the work on structural acoustic control of sound radiation has focused on reducing sound radiation from individual panels into an acoustic space. Research by the authors seeks to bridge this gap by considering the transmission of sound from individual panels on the fuselage to the interior of the aircraft. As part of this research, an analytical model of a curved panel, with attached piezoelectric actuators, subjected to a static pressure load was previously developed. In the present work, the analytical model is extended to consider the coupling of a curved panel to the interior acoustics of a rigid-walled cylinder. Insight gained from an accurate analytical model of the dynamics of the noise transmission from the curved panels of the fuselage into the cylindrical enclosure of an aircraft is essential to the development of feedback control systems for the control of stochastic inputs, such as turbulent boundary layer excitation. The criteria for maximal structural acoustic coupling between the modes of the curved panel and the modes of the cylindrical enclosure are studied. For panels with aspect ratios typical of those found in aircraft, results indicate that predominately axial structural modes couple most efficiently to the acoustic modes of the enclosure. The effects of the position of the curved panel on the cylinder are also studied. Structural acoustic coupling is found to not be significantly affected by varying panel position. The impact of the findings of this study on structural acoustic control design is discussed.

Time-resolved acoustic emission tomography in the laboratory: tracking localised damage in rocks

NASA Astrophysics Data System (ADS)

Brantut, N.

2017-12-01

Over the past three decades, there has been tremendous technological developments of laboratory equipment and studies using acoustic emission and ultrasonic monitoring of rock samples during deformation. Using relatively standard seismological techniques, acoustic emissions can be detected, located in space and time, and source mechanisms can be obtained. In parallel, ultrasonic velocities can be measured routinely using standard pulse-receiver techniques.Despite these major developments, current acoustic emission and ultrasonic monitoring systems are typically used separately, and the poor spatial coverage of acoustic transducers precludes performing active 3D tomography in typical laboratory settings.Here, I present an algorithm and software package that uses both passive acoustic emission data and active ultrasonic measurements to determine acoustic emission locations together with the 3D, anisotropic P-wave structure of rock samples during deformation. The technique is analogous to local earthquake tomography, but tailored to the specificities of small scale laboratory tests. The fast marching method is employed to compute the forward problem. The acoustic emission locations and the anisotropic P-wave field are jointly inverted using the Quasi-Newton method.The method is used to track the propagation of compaction bands in a porous sandstone deformed in the ductile, cataclastic flow regime under triaxial stress conditions. Near the yield point, a compaction front forms at one end of the sample, and slowly progresses towards the other end. The front is illuminated by clusters of Acoustic Emissions, and leaves behind a heavily damaged material where the P-wave speed has dropped by up to 20%.The technique opens new possibilities to track in-situ strain localisation and damage around laboratory faults, and preliminary results on quasi-static rupture in granite will be presented.

Active suppression of acoustically induced jitter for the airborne laser

NASA Astrophysics Data System (ADS)

Glaese, Roger M.; Anderson, Eric H.; Janzen, Paul C.

2000-07-01

The Airborne Laser (ABL) system has extremely tight jitter requirements. Acoustic disturbances, such as those caused by the pressure recovery system of the high power laser, are a significant jitter source. Several technologies may be appropriate for reducing the acoustically induced jitter. The first choice for mitigation will be passive approaches, such as acoustic blankets. There is, however, some uncertainty whether these approaches will provide sufficient attenuation and there is concern about the weight of these approaches. A testbed that captured the fundamental physics of the ABL acoustically induced optical jitter problem was developed. This testbed consists of a flexure-mounted mirror exposed to an acoustic field that is generated outside a beam tube and then propagates within the tube. Both feedback and adaptive feedforward control topologies were implemented on the testbed using either of two actuators (a fast steering mirror and a secondary acoustic speaker located near the precision mirror), and a variety of sensors (microphones measuring the acoustic disturbance, accelerometers and microphones mounted on the precision optic, and an optical position sensing detector). This paper summarizes the results from these control topologies for reducing the acoustically induced jitter with some control topologies achieving in excess of 40 dB jitter reduction at a single frequency. This work was performed under an SBIR Phase I funded by the Air Force Research Laboratory Space Vehicles Directorate.

Non-blind acoustic invisibility by dual layers of homogeneous single-negative media

NASA Astrophysics Data System (ADS)

Gao, He; Zhu, Yi-Fan; Fan, Xu-Dong; Liang, Bin; Yang, Jing; Cheng, Jian-Chun

2017-02-01

Non-blind invisibility cloaks allowing the concealed object to sense the outside world have great application potentials such as in high-precision sensing or underwater camouflage. However the existing designs based on coordinate transformation techniques need complicated spatially-varying negative index or intricate multi-layered configurations, substantially increasing the difficulty in practical realization. Here we report on the non-blind acoustic invisibility for a circular object in free space with simple distribution of cloak parameters. The mechanism is that, instead of utilizing the transformation acoustics technique, we develop the analytical formulae for fast prediction of the scattering from the object and then use an evolutionary optimization to retrieve the desired cloak parameters for minimizing the scattered field. In this way, it is proven possible to break through the fundamental limit of complementary condition that must be satisfied by the effective parameters of the components in transformation acoustics-based cloaks. Numerical results show that the resulting cloak produces a non-bflind invisibility as perfect as in previous designs, but only needs two layers with homogenous single-negative parameters. With full simplification in parameter distribution and broken symmetry in complementary relationship, our scheme opens new route to free-space non-blind invisibility, taking a significant step towards real-world application of cloaking devices.

Non-blind acoustic invisibility by dual layers of homogeneous single-negative media

PubMed Central

Gao, He; Zhu, Yi-fan; Fan, Xu-dong; Liang, Bin; Yang, Jing; Cheng, Jian-Chun

2017-01-01

Non-blind invisibility cloaks allowing the concealed object to sense the outside world have great application potentials such as in high-precision sensing or underwater camouflage. However the existing designs based on coordinate transformation techniques need complicated spatially-varying negative index or intricate multi-layered configurations, substantially increasing the difficulty in practical realization. Here we report on the non-blind acoustic invisibility for a circular object in free space with simple distribution of cloak parameters. The mechanism is that, instead of utilizing the transformation acoustics technique, we develop the analytical formulae for fast prediction of the scattering from the object and then use an evolutionary optimization to retrieve the desired cloak parameters for minimizing the scattered field. In this way, it is proven possible to break through the fundamental limit of complementary condition that must be satisfied by the effective parameters of the components in transformation acoustics-based cloaks. Numerical results show that the resulting cloak produces a non-bflind invisibility as perfect as in previous designs, but only needs two layers with homogenous single-negative parameters. With full simplification in parameter distribution and broken symmetry in complementary relationship, our scheme opens new route to free-space non-blind invisibility, taking a significant step towards real-world application of cloaking devices. PMID:28195227

Volpe Center Acoustics Facility time-space-position-information system differential global positioning system user's guide, version 1.2

DOT National Transportation Integrated Search

2000-07-01

This document is a users guide for the VolpeCenter AcousticsFacilitys(VCAF)Time-Space-Position-Information : (TSPI) System. The VCAF TSPI system is a differential global positioning system (dGPS) which may be utilized : for highly accurate vehi...

Acoustic environmental accuracy requirements for response determination

NASA Technical Reports Server (NTRS)

Pettitt, M. R.

1983-01-01

A general purpose computer program was developed for the prediction of vehicle interior noise. This program, named VIN, has both modal and statistical energy analysis capabilities for structural/acoustic interaction analysis. The analytic models and their computer implementation were verified through simple test cases with well-defined experimental results. The model was also applied in a space shuttle payload bay launch acoustics prediction study. The computer program processes large and small problems with equal efficiency because all arrays are dynamically sized by program input variables at run time. A data base is built and easily accessed for design studies. The data base significantly reduces the computational costs of such studies by allowing the reuse of the still-valid calculated parameters of previous iterations.

Acoustics and Surface Pressure Measurements from Tandem Cylinder Configurations

NASA Technical Reports Server (NTRS)

Hutcheson, Florence V.; Brooks, Thomas F.; Lockard, David P.; Choudhari, Meelan M.; Stead, Daniel J.

2014-01-01

Acoustic and unsteady surface pressure measurements from two cylinders in tandem configurations were acquired to study the effect of spacing, surface trip and freestream velocity on the radiated noise. The Reynolds number ranged from 1.15x10(exp 5) to 2.17x10(exp 5), and the cylinder spacing varied between 1.435 and 3.7 cylinder diameters. The acoustic and surface pressure spectral characteristics associated with the different flow regimes produced by the cylinders' wake interference were identified. The dependence of the Strouhal number, peak Sound Pressure Level and spanwise coherence on cylinder spacing and flow velocity was examined. Directivity measurements were performed to determine how well the dipole assumption for the radiation of vortex shedding noise holds for the largest and smallest cylinder spacing tested.

Classifiers utilized to enhance acoustic based sensors to identify round types of artillery/mortar

NASA Astrophysics Data System (ADS)

Grasing, David; Desai, Sachi; Morcos, Amir

2008-04-01

Feature extraction methods based on the statistical analysis of the change in event pressure levels over a period and the level of ambient pressure excitation facilitate the development of a robust classification algorithm. The features reliably discriminates mortar and artillery variants via acoustic signals produced during the launch events. Utilizing acoustic sensors to exploit the sound waveform generated from the blast for the identification of mortar and artillery variants as type A, etcetera through analysis of the waveform. Distinct characteristics arise within the different mortar/artillery variants because varying HE mortar payloads and related charges emphasize varying size events at launch. The waveform holds various harmonic properties distinct to a given mortar/artillery variant that through advanced signal processing and data mining techniques can employed to classify a given type. The skewness and other statistical processing techniques are used to extract the predominant components from the acoustic signatures at ranges exceeding 3000m. Exploiting these techniques will help develop a feature set highly independent of range, providing discrimination based on acoustic elements of the blast wave. Highly reliable discrimination will be achieved with a feedforward neural network classifier trained on a feature space derived from the distribution of statistical coefficients, frequency spectrum, and higher frequency details found within different energy bands. The processes that are described herein extend current technologies, which emphasis acoustic sensor systems to provide such situational awareness.

Artillery/mortar type classification based on detected acoustic transients

NASA Astrophysics Data System (ADS)

Morcos, Amir; Grasing, David; Desai, Sachi

2008-04-01

Feature extraction methods based on the statistical analysis of the change in event pressure levels over a period and the level of ambient pressure excitation facilitate the development of a robust classification algorithm. The features reliably discriminates mortar and artillery variants via acoustic signals produced during the launch events. Utilizing acoustic sensors to exploit the sound waveform generated from the blast for the identification of mortar and artillery variants as type A, etcetera through analysis of the waveform. Distinct characteristics arise within the different mortar/artillery variants because varying HE mortar payloads and related charges emphasize varying size events at launch. The waveform holds various harmonic properties distinct to a given mortar/artillery variant that through advanced signal processing and data mining techniques can employed to classify a given type. The skewness and other statistical processing techniques are used to extract the predominant components from the acoustic signatures at ranges exceeding 3000m. Exploiting these techniques will help develop a feature set highly independent of range, providing discrimination based on acoustic elements of the blast wave. Highly reliable discrimination will be achieved with a feed-forward neural network classifier trained on a feature space derived from the distribution of statistical coefficients, frequency spectrum, and higher frequency details found within different energy bands. The processes that are described herein extend current technologies, which emphasis acoustic sensor systems to provide such situational awareness.

Analytical modeling of the structureborne noise path on a small twin-engine aircraft

NASA Technical Reports Server (NTRS)

Cole, J. E., III; Stokes, A. Westagard; Garrelick, J. M.; Martini, K. F.

1988-01-01

The structureborne noise path of a six passenger twin-engine aircraft is analyzed. Models of the wing and fuselage structures as well as the interior acoustic space of the cabin are developed and used to evaluate sensitivity to structural and acoustic parameters. Different modeling approaches are used to examine aspects of the structureborne path. These approaches are guided by a number of considerations including the geometry of the structures, the frequency range of interest, and the tractability of the computations. Results of these approaches are compared with experimental data.

Acoustic charge transport technology investigation for advanced development transponder

NASA Technical Reports Server (NTRS)

Kayalar, S.

1993-01-01

Acoustic charge transport (ACT) technology has provided a basis for a new family of analog signal processors, including a programmable transversal filter (PTF). Through monolithic integration of ACT delay lines with GaAs metal semiconductor field effect transistor (MESFET) digital memory and controllers, these devices significantly extend the performance of PTF's. This article introduces the basic operation of these devices and summarizes their present and future specifications. The production and testing of these devices indicate that this new technology is a promising one for future space applications.

Acoustic Shaping: Enabling Technology for a Space-Based Economy

NASA Astrophysics Data System (ADS)

Komerath, N. M.; Matos, C. A.; Coker, A.; Wanis, S.; Hausaman, J.; Ames, R. G.; Tan, X. Y.

1999-01-01

This abstract presents three points for discussion: (1) Key to the development of civilization in space, is a space-based marketplace, where the need to compete in earth-based markets is removed, along with the constraint of launch costs from Earth. (2) A body of technical results, obtained by the authors' team, indicates promise for non-contact manufacturing in space, of low-cost items required for human presence in space. This is presented along with various other techniques which hold promise. (3) The economics of starting a space-based production company are heavily dependent on the presence of a rudimentary infrastructure. A national-level investment in space-based infrastructure, would be an essential catalyst for the development of a space-based economy. Some suggestions for the beginnings of this infrastructure are repeated from the literature.

Predicting the effect of urban noise on the active space of avian vocal signals.

PubMed

Parris, Kirsten M; McCarthy, Michael A

2013-10-01

Urbanization changes the physical environment of nonhuman species but also markedly changes their acoustic environment. Urban noise interferes with acoustic communication in a range of animals, including birds, with potentially profound impacts on fitness. However, a mechanistic theory to predict which species of birds will be most affected by urban noise is lacking. We develop a mathematical model to predict the decrease in the active space of avian vocal signals after moving from quiet forest habitats to noisy urban habitats. We find that the magnitude of the decrease is largely a function of signal frequency. However, this relationship is not monotonic. A metaregression of observed increases in the frequency of birdsong in urban noise supports the model's predictions for signals with frequencies between 1.5 and 4 kHz. Using results of the metaregression and the model described above, we show that the expected gain in active space following observed frequency shifts is up to 12% and greatest for birds with signals at the lower end of this frequency range. Our generally applicable model, along with three predictions regarding the behavioral and population-level responses of birds to urban noise, represents an important step toward a theory of acoustic communication in urban habitats.

Space-Time Conservation Element and Solution Element Method Being Developed

NASA Technical Reports Server (NTRS)

Chang, Sin-Chung; Himansu, Ananda; Jorgenson, Philip C. E.; Loh, Ching-Yuen; Wang, Xiao-Yen; Yu, Sheng-Tao

1999-01-01

The engineering research and design requirements of today pose great computer-simulation challenges to engineers and scientists who are called on to analyze phenomena in continuum mechanics. The future will bring even more daunting challenges, when increasingly complex phenomena must be analyzed with increased accuracy. Traditionally used numerical simulation methods have evolved to their present state by repeated incremental extensions to broaden their scope. They are reaching the limits of their applicability and will need to be radically revised, at the very least, to meet future simulation challenges. At the NASA Lewis Research Center, researchers have been developing a new numerical framework for solving conservation laws in continuum mechanics, namely, the Space-Time Conservation Element and Solution Element Method, or the CE/SE method. This method has been built from fundamentals and is not a modification of any previously existing method. It has been designed with generality, simplicity, robustness, and accuracy as cornerstones. The CE/SE method has thus far been applied in the fields of computational fluid dynamics, computational aeroacoustics, and computational electromagnetics. Computer programs based on the CE/SE method have been developed for calculating flows in one, two, and three spatial dimensions. Results have been obtained for numerous problems and phenomena, including various shock-tube problems, ZND detonation waves, an implosion and explosion problem, shocks over a forward-facing step, a blast wave discharging from a nozzle, various acoustic waves, and shock/acoustic-wave interactions. The method can clearly resolve shock/acoustic-wave interactions, wherein the difference of the magnitude between the acoustic wave and shock could be up to six orders. In two-dimensional flows, the reflected shock is as crisp as the leading shock. CE/SE schemes are currently being used for advanced applications to jet and fan noise prediction and to chemically reacting flows.

Tutorial on architectural acoustics

NASA Astrophysics Data System (ADS)

Shaw, Neil; Talaske, Rick; Bistafa, Sylvio

2002-11-01

This tutorial is intended to provide an overview of current knowledge and practice in architectural acoustics. Topics covered will include basic concepts and history, acoustics of small rooms (small rooms for speech such as classrooms and meeting rooms, music studios, small critical listening spaces such as home theatres) and the acoustics of large rooms (larger assembly halls, auditoria, and performance halls).

Acoustic source for generating an acoustic beam

DOEpatents

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.

Detection of spatio-temporal change of ocean acoustic velocity for observing seafloor crustal deformation applying seismological methods

NASA Astrophysics Data System (ADS)

Eto, S.; Nagai, S.; Tadokoro, K.

2011-12-01

Our group has developed a system for observing seafloor crustal deformation with a combination of acoustic ranging and kinematic GPS positioning techniques. One of the effective factors to reduce estimation error of submarine benchmark in our system is modeling variation of ocean acoustic velocity. We estimated various 1-dimensional velocity models with depth under some constraints, because it is difficult to estimate 3-dimensional acoustic velocity structure including temporal change due to our simple acquisition procedure of acoustic ranging data. We, then, applied the joint hypocenter determination method in seismology [Kissling et al., 1994] to acoustic ranging data. We assume two conditions as constraints in inversion procedure as follows: 1) fixed acoustic velocity in deeper part because it is usually stable both in space and time, 2) each inverted velocity model should be decreased with depth. The following two remarkable spatio-temporal changes of acoustic velocity 1) variations of travel-time residuals at the same points within short time and 2) larger differences between residuals at the neighboring points, which are one's of travel-time from different benchmarks. The First results cannot be explained only by the effect of atmospheric condition change including heating by sunlight. To verify the residual variations mentioned as the second result, we have performed forward modeling of acoustic ranging data with velocity models added velocity anomalies. We calculate travel time by a pseudo-bending ray tracing method [Um and Thurber, 1987] to examine effects of velocity anomaly on the travel-time differences. Comparison between these residuals and travel-time difference in forward modeling, velocity anomaly bodies in shallower depth can make these anomalous residuals, which may indicate moving water bodies. We need to apply an acoustic velocity structure model with velocity anomaly(s) in acoustic ranging data analysis and/or to develop a new system with a large number of sea surface stations to detect them, which may be able to reduce error of seafloor benchmarker position.

Acoustic structure of the five perceptual dimensions of timbre in orchestral instrument tones

PubMed Central

Elliott, Taffeta M.; Hamilton, Liberty S.; Theunissen, Frédéric E.

2013-01-01

Attempts to relate the perceptual dimensions of timbre to quantitative acoustical dimensions have been tenuous, leading to claims that timbre is an emergent property, if measurable at all. Here, a three-pronged analysis shows that the timbre space of sustained instrument tones occupies 5 dimensions and that a specific combination of acoustic properties uniquely determines gestalt perception of timbre. Firstly, multidimensional scaling (MDS) of dissimilarity judgments generated a perceptual timbre space in which 5 dimensions were cross-validated and selected by traditional model comparisons. Secondly, subjects rated tones on semantic scales. A discriminant function analysis (DFA) accounting for variance of these semantic ratings across instruments and between subjects also yielded 5 significant dimensions with similar stimulus ordination. The dimensions of timbre space were then interpreted semantically by rotational and reflectional projection of the MDS solution into two DFA dimensions. Thirdly, to relate this final space to acoustical structure, the perceptual MDS coordinates of each sound were regressed with its joint spectrotemporal modulation power spectrum. Sound structures correlated significantly with distances in perceptual timbre space. Contrary to previous studies, most perceptual timbre dimensions are not the result of purely temporal or spectral features but instead depend on signature spectrotemporal patterns. PMID:23297911

Acoustics of Italian Historical Opera Houses.

PubMed

Prodi, Nicola; Pompoli, Roberto; Martellotta, Francesco; Sato, Shin-ichi

2015-08-01

Opera houses represent a large group of performance spaces characterized by great complexity and, at the same time, versatility with respect to different usage (from opera to symphonic music and ballet). This kind of building originated in Italy during the 17th century and later spread across the country and then Europe and the rest of the world, slowly evolving into modern theatre shapes. As a consequence of the changes undergone by the interior space, the original acoustic features, which likely influenced many composers, experienced important variations. Thanks to acoustic measurement campaigns inside Italian Historical Opera Houses, promoted by National and Regional Projects, the distinctive features of these spaces were investigated in comparison to modern spaces. In this work, the newly acquired data are merged with data in the literature in order to present and discuss some of the distinctive acoustic features of historical spaces as regards their original function. Moreover, specific issues such as listening in stalls and boxes and the criteria governing the preference judgment of listeners are considered. The concept and the crucial role of the balance between stage and pit sources are also discussed by means of previous literature studies.

Opportunities for the chemical industry in space, part 1

NASA Technical Reports Server (NTRS)

1984-01-01

The chemical/petrochemical industry devotes a large percentage of its gross income to research and development, with much of its R and D of a long-term nature. As the chemical industry is examined as a candidate for space investigations, it is readily apparent that research and development in the space environment may lead to attractive commercial opportunities. The advantages of low gravity manufacturing, with a particular emphasis on chemical catalysts, are presented herein specifically for the chemical industry. Research from the Skylab program and Apollo Soyuz test project is reviewed, including acoustic levitation, crystal growth, and container less melts. Space processing of composite materials, alloys, and coatings is also discussed.

Performance of an underwater acoustic volume array using time-reversal focusing

NASA Astrophysics Data System (ADS)

Root, Joseph A.; Rogers, Peter H.

2002-11-01

Time reversal permits acoustic focusing and beam forming in inhomogeneous and/or high-scattering environments. A volumetric array geometry can suppress back lobes and can fit a large, powerful array of elements into small spaces, like the free-water spaces on submarines. This research investigates applying the time-reversal method to an underwater acoustic volume array. The experiments evaluate the focusing performance of a 27-element volume array when different scattering structures are present within the volume of the array. The array is arranged in a 3 x3 x3 cubic matrix configuration with 18.75-cm vertical and horizontal element spacing. The system utilizes second-derivative Gaussian pulses to focus on a point 30 cm from the array. Results include a comparison between time-reversal focusing and standard focusing, an evaluation of the volume array's ability to suppress back lobes, and an analysis of how different scattering environments affect focal region size. Potential underwater applications for a volume array using time reversal include acoustic imaging, naval mine hunting, sonar, and underwater communications. copyright 2002 Acoustical Society of America.

Experimental investigation of acoustic self-oscillation influence on decay process for underexpanded supersonic jet in submerged space

NASA Astrophysics Data System (ADS)

Aleksandrov, V. Yu.; Arefyev, K. Yu.; Ilchenko, M. A.

2016-07-01

Intensification of mixing between the gaseous working body ejected through a jet nozzle with ambient medium is an important scientific and technical problem. Effective mixing can increase the total efficiency of power and propulsion apparatuses. The promising approach, although poorly studied, is generation of acoustic self-oscillation inside the jet nozzle: this impact might enhance the decay of a supersonic jet and improve the mixing parameters. The paper presents peculiar properties of acoustic self-excitation in jet nozzle. The paper presents results of experimental study performed for a model injector with a set of plates placed into the flow channel, enabling the excitation of acoustic self-oscillations. The study reveals the regularity of under-expanded supersonic jet decay in submerged space for different flow modes. Experimental data support the efficiency of using the jet nozzle with acoustic self-oscillation in application to the systems of gas fuel supply. Experimental results can be used for designing new power apparatuses for aviation and space industry and for process plants.

Locating arbitrarily time-dependent sound sources in three dimensional space in real time.

PubMed

Wu, Sean F; Zhu, Na

2010-08-01

This paper presents a method for locating arbitrarily time-dependent acoustic sources in a free field in real time by using only four microphones. This method is capable of handling a wide variety of acoustic signals, including broadband, narrowband, impulsive, and continuous sound over the entire audible frequency range, produced by multiple sources in three dimensional (3D) space. Locations of acoustic sources are indicated by the Cartesian coordinates. The underlying principle of this method is a hybrid approach that consists of modeling of acoustic radiation from a point source in a free field, triangulation, and de-noising to enhance the signal to noise ratio (SNR). Numerical simulations are conducted to study the impacts of SNR, microphone spacing, source distance and frequency on spatial resolution and accuracy of source localizations. Based on these results, a simple device that consists of four microphones mounted on three mutually orthogonal axes at an optimal distance, a four-channel signal conditioner, and a camera is fabricated. Experiments are conducted in different environments to assess its effectiveness in locating sources that produce arbitrarily time-dependent acoustic signals, regardless whether a sound source is stationary or moves in space, even toward behind measurement microphones. Practical limitations on this method are discussed.

An investigation of acoustic noise requirements for the Space Station centrifuge facility

NASA Technical Reports Server (NTRS)

Castellano, Timothy

1994-01-01

Acoustic noise emissions from the Space Station Freedom (SSF) centrifuge facility hardware represent a potential technical and programmatic risk to the project. The SSF program requires that no payload exceed a Noise Criterion 40 (NC-40) noise contour in any octave band between 63 Hz and 8 kHz as measured 2 feet from the equipment item. Past experience with life science experiment hardware indicates that this requirement will be difficult to meet. The crew has found noise levels on Spacelab flights to be unacceptably high. Many past Ames Spacelab life science payloads have required waivers because of excessive noise. The objectives of this study were (1) to develop an understanding of acoustic measurement theory, instruments, and technique, and (2) to characterize the noise emission of analogous Facility components and previously flown flight hardware. Test results from existing hardware were reviewed and analyzed. Measurements of the spectral and intensity characteristics of fans and other rotating machinery were performed. The literature was reviewed and contacts were made with NASA and industry organizations concerned with or performing research on noise control.

Simple Solutions for Space Station Audio Problems

NASA Technical Reports Server (NTRS)

Wood, Eric

2016-01-01

Throughout this summer, a number of different projects were supported relating to various NASA programs, including the International Space Station (ISS) and Orion. The primary project that was worked on was designing and testing an acoustic diverter which could be used on the ISS to increase sound pressure levels in Node 1, a module that does not have any Audio Terminal Units (ATUs) inside it. This acoustic diverter is not intended to be a permanent solution to providing audio to Node 1; it is simply intended to improve conditions while more permanent solutions are under development. One of the most exciting aspects of this project is that the acoustic diverter is designed to be 3D printed on the ISS, using the 3D printer that was set up earlier this year. Because of this, no new hardware needs to be sent up to the station, and no extensive hardware testing needs to be performed on the ground before sending it to the station. Instead, the 3D part file can simply be uploaded to the station's 3D printer, where the diverter will be made.

Evaluation of a multi-point method for determining acoustic impedance

NASA Technical Reports Server (NTRS)

Jones, Michael G.; Parrott, Tony L.

1988-01-01

An investigation was conducted to explore potential improvements provided by a Multi-Point Method (MPM) over the Standing Wave Method (SWM) and Two-Microphone Method (TMM) for determining acoustic impedance. A wave propagation model was developed to model the standing wave pattern in an impedance tube. The acoustic impedance of a test specimen was calculated from a best fit of this standing wave pattern to pressure measurements obtained along the impedance tube centerline. Three measurement spacing distributions were examined: uniform, random, and selective. Calculated standing wave patterns match the point pressure measurement distributions with good agreement for a reflection factor magnitude range of 0.004 to 0.999. Comparisons of results using 2, 3, 6, and 18 measurement points showed that the most consistent results are obtained when using at least 6 evenly spaced pressure measurements per half-wavelength. Also, data were acquired with broadband noise added to the discrete frequency noise and impedances were calculated using the MPM and TMM algorithms. The results indicate that the MPM will be superior to the TMM in the presence of significant broadband noise levels associated with mean flow.

SpaceX Dragon Air Circulation System

NASA Technical Reports Server (NTRS)

Hernandez, Brenda; Piatrovich, Siarhei; Prina, Mauro

2011-01-01

The Dragon capsule is a reusable vehicle being developed by Space Exploration Technologies (SpaceX) that will provide commercial cargo transportation to the International Space Station (ISS). Dragon is designed to be a habitable module while it is berthed to ISS. As such, the Dragon Environmental Control System (ECS) consists of pressure control and pressure equalization, air sampling, fire detection, illumination, and an air circulation system. The air circulation system prevents pockets of stagnant air in Dragon that can be hazardous to the ISS crew. In addition, through the inter-module duct, the air circulation system provides fresh air from ISS into Dragon. To utilize the maximum volume of Dragon for cargo packaging, the Dragon ECS air circulation system is designed around cargo rack optimization. At the same time, the air circulation system is designed to meet the National Aeronautics Space Administration (NASA) inter-module and intra-module ventilation requirements and acoustic requirements. A flight like configuration of the Dragon capsule including the air circulation system was recently assembled for testing to assess the design for inter-module and intra-module ventilation and acoustics. The testing included the Dragon capsule, and flight configuration in the pressure section with cargo racks, lockers, all of the air circulation components, and acoustic treatment. The air circulation test was also used to verify the Computational Fluid Dynamics (CFD) model of the Dragon capsule. The CFD model included the same Dragon internal geometry that was assembled for the test. This paper will describe the Dragon air circulation system design which has been verified by testing the system and with CFD analysis.

A wideband fast multipole boundary element method for half-space/plane-symmetric acoustic wave problems

NASA Astrophysics Data System (ADS)

Zheng, Chang-Jun; Chen, Hai-Bo; Chen, Lei-Lei

2013-04-01

This paper presents a novel wideband fast multipole boundary element approach to 3D half-space/plane-symmetric acoustic wave problems. The half-space fundamental solution is employed in the boundary integral equations so that the tree structure required in the fast multipole algorithm is constructed for the boundary elements in the real domain only. Moreover, a set of symmetric relations between the multipole expansion coefficients of the real and image domains are derived, and the half-space fundamental solution is modified for the purpose of applying such relations to avoid calculating, translating and saving the multipole/local expansion coefficients of the image domain. The wideband adaptive multilevel fast multipole algorithm associated with the iterative solver GMRES is employed so that the present method is accurate and efficient for both lowand high-frequency acoustic wave problems. As for exterior acoustic problems, the Burton-Miller method is adopted to tackle the fictitious eigenfrequency problem involved in the conventional boundary integral equation method. Details on the implementation of the present method are described, and numerical examples are given to demonstrate its accuracy and efficiency.

Space-coiling fractal metamaterial with multi-bandgaps on subwavelength scale

NASA Astrophysics Data System (ADS)

Man, Xianfeng; Liu, Tingting; Xia, Baizhan; Luo, Zhen; Xie, Longxiang; Liu, Jian

2018-06-01

Acoustic metamaterials are remarkably different from conventional materials, as they can flexibly manipulate and control the propagation of sound waves. Unlike the locally resonant metamaterials introduced in earlier studies, we designed an ultraslow artificial structure with a sound speed much lower than that in air. In this paper, the space-coiling approach is proposed for achieving artificial metamaterial for extremely low-frequency airborne sound. In addition, the self-similar fractal technique is utilized for designing space-coiling Mie-resonance-based metamaterials (MRMMs) to obtain a band-dispersive spectrum. The band structures of two-dimensional (2D) acoustic metamaterials with different fractal levels are illustrated using the finite element method. The low-frequency bandgap can easily be formed, and multi-bandgap properties are observed in high-level fractals. Furthermore, the designed MRMMs with higher order fractal space coiling shows a good robustness against irregular arrangement. Besides, the proposed artificial structure was found to modify and control the radiation field arbitrarily. Thus, this work provides useful guidelines for the design of acoustic filtering devices and acoustic wavefront shaping applications on the subwavelength scale.

Listening in circles. Spoken drama and the architects of sound, 1750-1830.

PubMed

Tkaczyk, Viktoria

2014-07-01

The establishment of the discipline of architectural acoustics is generally attributed to the physicist Wallace Clement Sabine, who developed the formula for reverberation time around 1900, and with it the possibility of making calculated prognoses about the acoustic potential of a particular design. If, however, we shift the perspective from the history of this discipline to the history of architectural knowledge and praxis, it becomes apparent that the topos of 'good sound' had already entered the discourse much earlier. This paper traces the Europe-wide discussion on theatre architecture between 1750 and 1830. It will be shown that the period of investigation is marked by an increasing interest in auditorium acoustics, one linked to the emergence of a bourgeois theatre culture and the growing socio-political importance of the spoken word. In the wake of this development the search among architects for new methods of acoustic research started to differ fundamentally from an analogical reasoning on the nature of sound propagation and reflection, which in part dated back to antiquity. Through their attempts to find new ways of visualising the behaviour of sound in enclosed spaces and to rethink both the materiality and the mediality of theatre auditoria, architects helped pave the way for the establishment of architectural acoustics as an academic discipline around 1900.

Demonstration of nonlinear effects in acoustic landmine experiments using a clamped-plate soil oscillator

NASA Astrophysics Data System (ADS)

Korman, Murray S.; Bond, Emilia

2005-09-01

Current nonlinear experiments involving the detection of plastic landmines using acoustic-to-seismic coupling have been developed from Sabatier's (linear) and Donskoy's (nonlinear) earlier methods. A laboratory apparatus called the soil-plate oscillator has been developed at the National Center for Physical Acoustics, and later at the U.S. Naval Academy, to model acoustic mine detection. The apparatus consists of a thick-walled cylinder filled with sifted homogeneous soil resting on a thin elastic plate that is clamped to the bottom of the column. It represents a good simplified physical model for VS 1.6 and VS 2.2 inert anti-tank plastic buried landmines. Using a loudspeaker (located over the soil) that is driven by a swept sinusoid, tuning curve experiments are performed. The vibration amplitude versus frequency is measured on a swept spectrum analyzer using an accelerometer located on the soil-air interface or under the plate. The backbone curve shows a linear decrease in peak frequency versus increasing amplitude. A two-tone test experiment is performed using two loudspeakers generating acoustic frequencies (closely spaced on either side of resonance, typically ~100 Hz). A rich vibration spectrum of combination frequency tones (along with the primaries) is observed which is characteristic of actual nonlinear detection schemes.

Detection and modelling of the ionospheric perturbation caused by a Space Shuttle launch using a network of ground-based Global Positioning System stations

NASA Astrophysics Data System (ADS)

Bowling, Timothy; Calais, Eric; Haase, Jennifer S.

2013-03-01

The exhaust plume of the Space Shuttle during its ascent triggers acoustic waves which propagate through the atmosphere and induce electron density changes at ionospheric heights which changes can be measured using ground-based Global Positioning System (GPS) phase data. Here, we use a network of GPS stations to study the acoustic wave generated by the STS-125 Space Shuttle launch on May 11, 2009. We detect the resulting changes in ionospheric electron density, with characteristics that are typical of acoustic waves triggered by explosions at or near the Earth's surface or in the atmosphere. We successfully reproduce the amplitude and timing of the observed signal using a ray-tracing model with a moving source whose amplitude is directly scaled by a physical model of the shuttle exhaust energy, acoustic propagation in a dispersive atmosphere and a simplified two-fluid model of collisions between neutral gas and free electrons in the ionosphere. The close match between observed and model waveforms validates the modelling approach. This raises the possibility of using ground-based GPS networks to estimate the acoustic energy release of explosive sources near the Earth's surface or in atmosphere, and to constrain some atmospheric acoustic parameters.

NRL Fact Book

DTIC Science & Technology

1988-05-01

interests are centered on signal processing and the physics of underwater acoustic propagation, ambient noise, and reverberation. Mr. Rojas is a member...Airborne underwater acoustics Bottom-limited acoustics Arctic underwater acoustics Propagation Noise Ambient noise measurements and modeling Spectral...Multispectral image correlation Space sensor and mission analysis CROWN" STALK Time, ms (100 ms after impactO Time-history of the . radar backscatter from a

International Space Station Acoustics - A Status Report

NASA Technical Reports Server (NTRS)

Allen, Christopher S.; Denham, Samuel A.

2011-01-01

It is important to control acoustic noise aboard the International Space Station (ISS) to provide a satisfactory environment for voice communications, crew productivity, and restful sleep, and to minimize the risk for temporary and permanent hearing loss. Acoustic monitoring is an important part of the noise control process on ISS, providing critical data for trend analysis, noise exposure analysis, validation of acoustic analysis and predictions, and to provide strong evidence for ensuring crew health and safety, thus allowing Flight Certification. To this purpose, sound level meter (SLM) measurements and acoustic noise dosimetry are routinely performed. And since the primary noise sources on ISS include the environmental control and life support system (fans and airflow) and active thermal control system (pumps and water flow), acoustic monitoring will indicate changes in hardware noise emissions that may indicate system degradation or performance issues. This paper provides the current acoustic levels in the ISS modules and sleep stations, and is an update to the status presented in 20031. Many new modules, and sleep stations have been added to the ISS since that time. In addition, noise mitigation efforts have reduced noise levels in some areas. As a result, the acoustic levels on the ISS have improved.

The European Spacelab structural design evolution

NASA Technical Reports Server (NTRS)

Thirkettle, A. J.

1982-01-01

Spacelab is a manned, reusable laboratory which is being developed for the European Space Agency (ESA). In its working mode it will fly in low earth orbit in the cargo bay of the Shuttle Transportation System (STS) Orbiter. A description is presented of the structural development of the various features of Spacelab. System requirements are considered along with structural requirements, quasi-static loads, acoustic loads, pressure loads, crash loads, ground loads, and the fatigue profile. Aspects of thermal environment generation are discussed, and questions regarding the design evolution of the pallet structure are examined. Details of pallet structure testing are reported, taking into account static strength tests, acoustic tests, the modal survey test, crash tests, and fatigue/fracture mechanics testing.

KSC-03PD-2377

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members take their places on one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2384

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin retrieve some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2381

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2369

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Dr. Grant Gilmore (left), Dynamac Corp., talks to another member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

SpaceX Crew Dragon Ship

NASA Image and Video Library

2018-05-20

The SpaceX Crew Dragon spacecraft is in the anechoic chamber for electromagnetic interference testing on May 20, 2018, at NASA's Kennedy Space Center in Florida. The Crew Dragon will be shipped to the agency's Plum Brook Station test facility at Glenn Research City in Cleveland, Ohio, for testing in the Reverberant Acoustic Test Facility, the world's most powerful acoustic test chamber. Crew Dragon is being prepared for its first uncrewed test flight, targeted for August 2018.

Experimental implementation of acoustic impedance control by a 2D network of distributed smart cells

NASA Astrophysics Data System (ADS)

David, P.; Collet, M.; Cote, J.-M.

2010-03-01

New miniaturization and integration capabilities available from emerging microelectromechanical system (MEMS) technology will allow silicon-based artificial skins involving thousands of elementary actuators to be developed in the near future. Smart structures combining large arrays of elementary motion pixels are thus being studied so that fundamental properties could be dynamically adjusted. This paper investigates the acoustical capabilities of a network of distributed transducers connected with a suitable controlling strategy. The research aims at designing an integrated active interface for sound attenuation by using suitable changes of acoustical impedance. The control strategy is based on partial differential equations (PDE) and the multiscaled physics of electromechanical elements. Specific techniques based on PDE control theory have provided a simple boundary control equation able to annihilate the reflections of acoustic waves. To experimentally implement the method, the control strategy is discretized as a first order time-space operator. The obtained quasi-collocated architecture, composed of a large number of sensors and actuators, provides high robustness and stability. The experimental results demonstrate how a well controlled active skin can substantially modify sound reflectivity of the acoustical interface and reduce the propagation of acoustic waves.

Determining Transmission Loss from Measured External and Internal Acoustic Environments

NASA Technical Reports Server (NTRS)

Scogin, Tyler; Smith, A. M.

2012-01-01

An estimate of the internal acoustic environment in each internal cavity of a launch vehicle is needed to ensure survivability of Space Launch System (SLS) avionics. Currently, this is achieved by using the noise reduction database of heritage flight vehicles such as the Space Shuttle and Saturn V for liftoff and ascent flight conditions. Marshall Space Flight Center (MSFC) is conducting a series of transmission loss tests to verify and augment this method. For this test setup, an aluminum orthogrid curved panel representing 1/8th of the circumference of a section of the SLS main structure was mounted in between a reverberation chamber and an anechoic chamber. Transmission loss was measured across the panel using microphones. Data measured during this test will be used to estimate the internal acoustic environments for several of the SLS launch vehicle internal spaces.

A general radiation model for sound fields and nearfield acoustical holography in wedge propagation spaces.

PubMed

Hoffmann, Falk-Martin; Fazi, Filippo Maria; Williams, Earl G; Fontana, Simone

2017-09-01

In this work an expression for the solution of the Helmholtz equation for wedge spaces is derived. Such propagation spaces represent scenarios for many acoustical problems where a free field assumption is not eligible. The proposed sound field model is derived from the general solution of the wave equation in cylindrical coordinates, using sets of orthonormal basis functions. The latter are modified to satisfy several boundary conditions representing the reflective behaviour of wedge-shaped propagation spaces. This formulation is then used in the context of nearfield acoustical holography (NAH) and to obtain the expression of the Neumann Green function. The model and its suitability for NAH is demonstrated through both numerical simulations and measured data, where the latter was acquired for the specific case of a loudspeaker on a hemi-cylindrical rigid baffle.

A double-panel active segmented partition module using decoupled analog feedback controllers: numerical model.

PubMed

Sagers, Jason D; Leishman, Timothy W; Blotter, Jonathan D

2009-06-01

Low-frequency sound transmission has long plagued the sound isolation performance of lightweight partitions. Over the past 2 decades, researchers have investigated actively controlled structures to prevent sound transmission from a source space into a receiving space. An approach using active segmented partitions (ASPs) seeks to improve low-frequency sound isolation capabilities. An ASP is a partition which has been mechanically and acoustically segmented into a number of small individually controlled modules. This paper provides a theoretical and numerical development of a single ASP module configuration, wherein each panel of the double-panel structure is independently actuated and controlled by an analog feedback controller. A numerical model is developed to estimate frequency response functions for the purpose of controller design, to understand the effects of acoustic coupling between the panels, to predict the transmission loss of the module in both passive and active states, and to demonstrate that the proposed ASP module will produce bidirectional sound isolation.

Adaptive acoustic energy delivery to near and far fields using foldable, tessellated star transducers

NASA Astrophysics Data System (ADS)

Zou, Chengzhe; Harne, Ryan L.

2017-05-01

Methods of guiding acoustic energy arbitrarily through space have long relied on digital controls to meet performance needs. Yet, more recent attention to adaptive structures with unique spatial configurations has motivated mechanical signal processing (MSP) concepts that may not be subjected to the same functional and performance limitations as digital acoustic beamforming counterparts. The periodicity of repeatable structural reconfiguration enabled by origami-inspired tessellated architectures turns attention to foldable platforms as frameworks for MSP development. This research harnesses principles of MSP to study a tessellated, star-shaped acoustic transducer constituent that provides on-demand control of acoustic energy guiding via folding-induced shape reconfiguration. An analytical framework is established to probe the roles of mechanical and acoustic geometry on the far field directivity and near field focusing of sound energy. Following validation by experiments and verification by simulations, parametric studies are undertaken to uncover relations between constituent topology and acoustic energy delivery to arbitrary points in the free field. The adaptations enabled by folding of the star-shaped transducer reveal capability for restricting sound energy to angular regions in the far field while also introducing means to modulate sound energy by three orders-of-magnitude to locations near to the transducer surface. In addition, the modeling philosophy devised here provides a valuable approach to solve general sound radiation problems for foldable, tessellated acoustic transducer constituents of arbitrary geometry.

Acoustic emission frequency discrimination

NASA Technical Reports Server (NTRS)

Sugg, Frank E. (Inventor); Graham, Lloyd J. (Inventor)

1988-01-01

In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.

Ultrasonic Waves in Water Visualized With Schlieren Imaging

NASA Technical Reports Server (NTRS)

Juergens, Jeffrey R.

2000-01-01

The Acoustic Liquid Manipulation project at the NASA Glenn Research Center at Lewis Field is working with high-intensity ultrasound waves to produce acoustic radiation pressure and acoustic streaming. These effects can be used to propel liquid flows to manipulate floating objects and liquid surfaces. Interest in acoustic liquid manipulation has been shown in acoustically enhanced circuit board electroplating, microelectromechanical systems (MEMS), and microgravity space experiments. The current areas of work on this project include phased-array ultrasonic beam steering, acoustic intensity measurements, and schlieren imaging of the ultrasonic waves.

Theoretical vibro-acoustic modeling of acoustic noise transmission through aircraft windows

NASA Astrophysics Data System (ADS)

Aloufi, Badr; Behdinan, Kamran; Zu, Jean

2016-06-01

In this paper, a fully vibro-acoustic model for sound transmission across a multi-pane aircraft window is developed. The proposed model is efficiently applied for a set of window models to perform extensive theoretical parametric studies. The studied window configurations generally simulate the passenger window designs of modern aircraft classes which have an exterior multi-Plexiglas pane, an interior single acrylic glass pane and a dimmable glass ("smart" glass), all separated by thin air cavities. The sound transmission loss (STL) characteristics of three different models, triple-, quadruple- and quintuple-paned windows identical in size and surface density, are analyzed for improving the acoustic insulation performances. Typical results describing the influence of several system parameters, such as the thicknesses, number and spacing of the window panes, on the transmission loss are then investigated. In addition, a comparison study is carried out to evaluate the acoustic reduction capability of each window model. The STL results show that the higher frequencies sound transmission loss performance can be improved by increasing the number of window panels, however, the low frequency performance is decreased, particularly at the mass-spring resonances.

Automation of vibroacoustic data bank for random vibration criteria development. [for the space shuttle and launch vehicles

NASA Technical Reports Server (NTRS)

Ferebee, R. C.

1982-01-01

A computerized data bank system was developed for utilization of large amounts of vibration and acoustic data to formulate component random vibration design and test criteria. This system consists of a computer, graphics tablet, and a dry-silver hard copier which are all desk-top type hardware and occupy minimal space. The data bank contains data from the Saturn V and Titan III flight and static test programs. The vibration and acoustic data are stored in the form of power spectral density and one-third octave band plots over the frequency range from 20 to 2000 Hz. The data was stored by digitizing each spectral plot by tracing with the graphics tablet. The digitized data was statistically analyzed and the resulting 97.5% probability levels were stored on tape along with the appropriate structural parameters. Standard extrapolation procedures were programmed for prediction of component random vibration test criteria for new launch vehicle and payload configurations. This automated vibroacoustic data bank system greatly enhances the speed and accuracy of formulating vibration test criteria. In the future, the data bank will be expanded to include all data acquired from the space shuttle flight test program.

Acoustic plane waves incident on an oblique clamped panel in a rectangular duct

NASA Technical Reports Server (NTRS)

Unz, H.; Roskam, J.

1980-01-01

The theory of acoustic plane waves incident on an oblique clamped panel in a rectangular duct was developed from basic theoretical concepts. The coupling theory between the elastic vibrations of the panel (plate) and the oblique incident acoustic plane wave in infinite space was considered in detail, and was used for the oblique clamped panel in the rectangular duct. The partial differential equation which governs the vibrations of the clamped panel (plate) was modified by adding to it stiffness (spring) forces and damping forces. The Transmission Loss coefficient and the Noise Reduction coefficient for oblique incidence were defined and derived in detail. The resonance frequencies excited by the free vibrations of the oblique finite clamped panel (plate) were derived and calculated in detail for the present case.

A Tool Measuring Remaining Thickness of Notched Acoustic Cavities in Primary Reaction Control Thruster NDI Standards

NASA Technical Reports Server (NTRS)

Sun, Yushi; Sun, Changhong; Zhu, Harry; Wincheski, Buzz

2006-01-01

Stress corrosion cracking in the relief radius area of a space shuttle primary reaction control thruster is an issue of concern. The current approach for monitoring of potential crack growth is nondestructive inspection (NDI) of remaining thickness (RT) to the acoustic cavities using an eddy current or remote field eddy current probe. EDM manufacturers have difficulty in providing accurate RT calibration standards. Significant error in the RT values of NDI calibration standards could lead to a mistaken judgment of cracking condition of a thruster under inspection. A tool based on eddy current principle has been developed to measure the RT at each acoustic cavity of a calibration standard in order to validate that the standard meets the sample design criteria.

Nonlinear Excitation of Acoustic Modes by Large Amplitude Alfvén waves in the Large Plasma Device (LAPD)

NASA Astrophysics Data System (ADS)

Dorfman, S. E.; Carter, T. A.; Pribyl, P.; Tripathi, S.; Van Compernolle, B.; Vincena, S. T.; Sydora, R. D.

2013-12-01

Alfvén waves, a fundamental mode of magnetized plasmas, are ubiquitous in space plasmas. While the linear behavior of these waves has been extensively studied [1], non-linear effects are important in many real systems, including the solar corona and solar wind. In particular, a parametric decay process in which a large amplitude Alfvén wave decays into an ion acoustic wave and backward propagating Alfvén wave may play an important role in the coronal heating problem. Specifically, the decay of large-amplitude Alfvén waves propagating outward from the photosphere could lead to heating of the corona by the daughter ion acoustic modes [2]. As direct observational evidence of parametric decay is limited [3], laboratory experiments may play an important role in validating simple theoretical predictions and aiding in the interpretation of space measurements. Recent counter-propagating Alfvén wave experiments in the Large Plasma Device (LAPD) have recorded the first laboratory observation of the Alfvén-acoustic mode coupling at the heart of this parametric decay instability [4]. A resonance in the beat wave response produced by the two launched Alfvén waves is observed and is identified as a damped ion acoustic mode based on the measured dispersion relation. Other properties of the interaction including the spatial profile of the beat mode and response amplitude are also consistent with theoretical predictions for a three-wave interaction driven by a nonlinear ponderomotive force. Strong damping observed after the pump Alfvén waves are turned off is under investigation; a novel ion acoustic wave launcher is under development to launch the mode directly for damping studies. New experiments also aim to identify decay instabilities from a single large-amplitude Alfvén wave. In conjunction with these experiments, gyrokinetic simulation efforts are underway to scope out the relevant parameter space. [1] W. Gekelman, et. al., Phys. Plasmas 18, 055501 (2011). [2] F. Pruneti, F and M. Velli, ESA Spec. Pub. 404, 623 (1997). [3] S. R. Spangler, et. al., Phys. Plasmas 4, 846 (1997). [4] S. Dorfman and T. Carter, Phys. Rev. Lett. 110, 195001 (2013).

Vibration, acoustic, and shock design and test criteria for components on the Solid Rocket Boosters (SRB), Lightweight External Tank (LWT), and Space Shuttle Main Engines (SSME)

NASA Technical Reports Server (NTRS)

1984-01-01

The vibration, acoustics, and shock design and test criteria for components and subassemblies on the space shuttle solid rocket booster (SRB), lightweight tank (LWT), and main engines (SSME) are presented. Specifications for transportation, handling, and acceptance testing are also provided.

An assessment of the microgravity and acoustic environments in Space Station Freedom using VAPEPS

NASA Technical Reports Server (NTRS)

Bergen, Thomas F.; Scharton, Terry D.; Badilla, Gloria A.

1992-01-01

The Vibroacoustic Payload Environment Prediction System (VAPEPS) was used to predict the stationary on-orbit environments in one of the Space Station Freedom modules. The model of the module included the outer structure, equipment and payload racks, avionics, and cabin air and duct systems. Acoustic and vibratory outputs of various source classes were derived and input to the model. Initial results of analyses, performed in one-third octave frequency bands from 10 to 10,000 Hz, show that both the microgravity and acoustic environments will be exceeded in some one-third octave bands with the current SSF design. Further analyses indicate that interior acoustic level requirements will be exceeded even if the microgravity requirements are met.

Rate and Loudness Manipulations in Dysarthria: Acoustic and Perceptual Findings.

ERIC Educational Resources Information Center

Tjaden, Kris; Wilding, Gregory E.

2004-01-01

Both rate reduction and increased loudness reportedly are associated with an increase in the size of the articulatory-acoustic working space and improved acoustic distinctiveness for speakers with dysarthria. Improved intelligibility also has been reported. Few studies have directly compared rate and loudness effects for speakers with dysarthria,…

14 CFR 36.7 - Acoustical change: Transport category large airplanes and jet airplanes.

Code of Federal Regulations, 2013 CFR

2013-01-01

... airplanes and jet airplanes. 36.7 Section 36.7 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... § 36.7 Acoustical change: Transport category large airplanes and jet airplanes. (a) Applicability. This section applies to all transport category large airplanes and jet airplanes for which an acoustical change...

14 CFR 36.7 - Acoustical change: Transport category large airplanes and jet airplanes.

Code of Federal Regulations, 2014 CFR

2014-01-01

... airplanes and jet airplanes. 36.7 Section 36.7 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... § 36.7 Acoustical change: Transport category large airplanes and jet airplanes. (a) Applicability. This section applies to all transport category large airplanes and jet airplanes for which an acoustical change...

14 CFR 36.7 - Acoustical change: Transport category large airplanes and jet airplanes.

Code of Federal Regulations, 2012 CFR

2012-01-01

... airplanes and jet airplanes. 36.7 Section 36.7 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... § 36.7 Acoustical change: Transport category large airplanes and jet airplanes. (a) Applicability. This section applies to all transport category large airplanes and jet airplanes for which an acoustical change...

The formation method of the feature space for the identification of fatigued bills

NASA Astrophysics Data System (ADS)

Kang, Dongshik; Oshiro, Ayumu; Ozawa, Kenji; Mitsui, Ikugo

2014-10-01

Fatigued bills make a trouble such as the paper jam in a bill handling machine. In the discrimination of fatigued bills using an acoustic signal, the variation of an observed bill sound is considered to be one of causes in misclassification. Therefore a technique has demanded in order to make the classification of fatigued bills more efficient. In this paper, we proposed the algorithm that extracted feature quantity of bill sound from acoustic signal using the frequency difference, and carried out discrimination experiment of fatigued bill money by Support Vector Machine(SVM). The feature quantity of frequency difference can represent the frequency components of an acoustic signal is varied by the fatigued degree of bill money. The generalization performance of SVM does not depend on the size of dimensions of the feature space, even in a high dimensional feature space such as bill-acoustic signals. Furthermore, SVM can induce an optimal classifier which considers the combination of features by the virtue of polynomial kernel functions.

Studies of elasticity, sound propagation and attenuation of acoustic modes in granular media: final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makse, Hernan A.; Johnson, David L.

2014-09-03

This is the final report describing the results of DOE Grant # DE-FG02-03ER15458 with original termination date of April 31, 2013, which has been extended to April 31, 2014. The goal of this project is to develop a theoretical and experimental understanding of sound propagation, elasticity and dissipation in granular materials. The topic is relevant for the efficient production of hydrocarbon and for identifying and characterizing the underground formation for storage of either CO 2 or nuclear waste material. Furthermore, understanding the basic properties of acoustic propagation in granular media is of importance not only to the energy industry, butmore » also to the pharmaceutical, chemical and agricultural industries. We employ a set of experimental, theoretical and computational tools to develop a study of acoustics and dissipation in granular media. These include the concept effective mass of granular media, normal modes analysis, statistical mechanics frameworks and numerical simulations based on Discrete Element Methods. Effective mass measurements allow us to study the mechanisms of the elastic response and attenuation of acoustic modes in granular media. We perform experiments and simulations under varying conditions, including humidity and vacuum, and different interparticle force-laws to develop a fundamental understanding of the mechanisms of damping and acoustic propagation in granular media. A theoretical statistical approach studies the necessary phase space of configurations in pressure, volume fraction to classify granular materials.« less

The Standard Deviation of Launch Vehicle Environments

NASA Technical Reports Server (NTRS)

Yunis, Isam

2005-01-01

Statistical analysis is used in the development of the launch vehicle environments of acoustics, vibrations, and shock. The standard deviation of these environments is critical to accurate statistical extrema. However, often very little data exists to define the standard deviation and it is better to use a typical standard deviation than one derived from a few measurements. This paper uses Space Shuttle and expendable launch vehicle flight data to define a typical standard deviation for acoustics and vibrations. The results suggest that 3dB is a conservative and reasonable standard deviation for the source environment and the payload environment.

Prototype Aerogel Insulation for Melamine-Foam Substitute: Critical Space Station Express Rack Technology

NASA Technical Reports Server (NTRS)

Noever, David A.; Sibille, Laurent; Smith, David; Cronise, Raymond

1998-01-01

There is a current lack of environmentally acceptable foams to insulate Long-Duration Human Spaceflight Missions, including the experimental Express Rack for the Space Station. A recent 60-day manned test in a sealed chamber at Johnson Space Center (JSC) was nearly aborted, because of persistently high formaldehyde concentrations in the chamber. Subsequent investigation showed that the source was melamine foam (used extensively for acoustic insulation). The thermal and acoustic potential for melamine-foam substitutes is evaluated for scale-up to a silica-based foam and aerogel, which is environmentally benign for long duration space flight. These features will be discussed in reference to an aerogel prototype to: 1) assemble material strength data for various formulated aerogels, both silica and organic carbon aerogels; 2) assemble the aerogel into panels of mylar/vacuum-encapsulated rigid boards which can be molded in various shapes and rigidities; and 3) describe a process for space applications for formaldehyde-free, long duration thermal and acoustic insulators.

Ethnographic model of acoustic use of space in the southern Andes for an archaeo-musicological investigation

NASA Astrophysics Data System (ADS)

Perez de Arce, Jose

2002-11-01

Studies of ritual celebrations in central Chile conducted in the past 15 years show that the spatial component of sound is a crucial component of the whole. The sonic compositions of these rituals generate complex musical structures that the author has termed ''multi-orchestral polyphonies.'' Their origins have been documented from archaeological remains in a vast region of southern Andes (southern Peru, Bolivia, northern Argentina, north-central Chile). It consists of a combination of dance, space walk-through, spatial extension, multiple movements between listener and orchestra, and multiple relations between ritual and ambient sounds. The characteristics of these observables reveal a complex schematic relation between space and sound. This schema can be used as a valid hypothesis for the study of pre-Hispanic uses of acoustic ritual space. The acoustic features observed in this study are common in Andean ritual and, to some extent are seen in Mesoamerica as well.

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.

Acoustic-Levitation Chamber

NASA Technical Reports Server (NTRS)

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

1984-01-01

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

Theoretical analysis of the sound absorption characteristics of periodically stiffened micro-perforated plates

NASA Astrophysics Data System (ADS)

Zhou, Hai-An; Wang, Xiao-Ming; Mei, Yu-Lin

2014-10-01

The vibro-acoustic responses and sound absorption characteristics of two kinds of periodically stiffened micro-perforated plates are analyzed theoretically. The connected periodical structures of the stiffened plates can be ribs or block-like structures. Based on fundamental acoustic formulas of the micro-perforated plate of Maa and Takahashi, semi-analytical models of the vibrating stiffened plates are developed in this paper. Approaches like the space harmonicmethod, Fourier transforms and finite elementmethod (FEM) are adopted to investigate both kinds of the stiffened plates. In the present work, the vibro-acoustic responses of micro-perforated stiffened plates in the wavenumber space are expressed as functions of plate displacement amplitudes. After approximate numerical solutions of the amplitudes, the vibration equations and sound absorption coefficients of the two kinds of stiffened plates in the physical space are then derived by employing the Fourier inverse transform. In numerical examples, the effects of some physical parameters, such as the perforation ratio, incident angles and periodical distances etc., on the sound absorption performance are examined. The proposed approaches are also validated by comparing the present results with solutions of Takahashi and previous studies of stiffened plates. Numerical results indicate that the flexural vibration of the plate has a significant effect on the sound absorption coefficient in the water but has little influence in the air.

Are you a good mimic? Neuro-acoustic signatures for speech imitation ability

PubMed Central

Reiterer, Susanne M.; Hu, Xiaochen; Sumathi, T. A.; Singh, Nandini C.

2013-01-01

We investigated individual differences in speech imitation ability in late bilinguals using a neuro-acoustic approach. One hundred and thirty-eight German-English bilinguals matched on various behavioral measures were tested for “speech imitation ability” in a foreign language, Hindi, and categorized into “high” and “low ability” groups. Brain activations and speech recordings were obtained from 26 participants from the two extreme groups as they performed a functional neuroimaging experiment which required them to “imitate” sentences in three conditions: (A) German, (B) English, and (C) German with fake English accent. We used recently developed novel acoustic analysis, namely the “articulation space” as a metric to compare speech imitation abilities of the two groups. Across all three conditions, direct comparisons between the two groups, revealed brain activations (FWE corrected, p < 0.05) that were more widespread with significantly higher peak activity in the left supramarginal gyrus and postcentral areas for the low ability group. The high ability group, on the other hand showed significantly larger articulation space in all three conditions. In addition, articulation space also correlated positively with imitation ability (Pearson's r = 0.7, p < 0.01). Our results suggest that an expanded articulation space for high ability individuals allows access to a larger repertoire of sounds, thereby providing skilled imitators greater flexibility in pronunciation and language learning. PMID:24155739

A novel unsplit perfectly matched layer for the second-order acoustic wave equation.

PubMed

Ma, Youneng; Yu, Jinhua; Wang, Yuanyuan

2014-08-01

When solving acoustic field equations by using numerical approximation technique, absorbing boundary conditions (ABCs) are widely used to truncate the simulation to a finite space. The perfectly matched layer (PML) technique has exhibited excellent absorbing efficiency as an ABC for the acoustic wave equation formulated as a first-order system. However, as the PML was originally designed for the first-order equation system, it cannot be applied to the second-order equation system directly. In this article, we aim to extend the unsplit PML to the second-order equation system. We developed an efficient unsplit implementation of PML for the second-order acoustic wave equation based on an auxiliary-differential-equation (ADE) scheme. The proposed method can benefit to the use of PML in simulations based on second-order equations. Compared with the existing PMLs, it has simpler implementation and requires less extra storage. Numerical results from finite-difference time-domain models are provided to illustrate the validity of the approach. Copyright © 2014 Elsevier B.V. All rights reserved.

Acoustic plane waves normally incident on a clamped panel in a rectangular duct. [to explain noise reduction curves for reducing interior noise in aircraft

NASA Technical Reports Server (NTRS)

Unz, H.; Roskam, J.

1979-01-01

The theory of acoustic plane wave normally incident on a clamped panel in a rectangular duct is developed. The coupling theory between the elastic vibrations of the panel (plate) and the acoustic wave propagation in infinite space and in the rectangular duct is considered. The partial differential equation which governs the vibration of the panel (plate) is modified by adding to its stiffness (spring) forces and damping forces, and the fundamental resonance frequency and the attenuation factor are discussed. The noise reduction expression based on the theory is found to agree well with the corresponding experimental data of a sample aluminum panel in the mass controlled region, the damping controlled region, and the stiffness controlled region. All the frequency positions of the upward and downward resonance spikes in the sample experimental data are identified theoretically as resulting from four cross interacting major resonance phenomena: the cavity resonance, the acoustic resonance, the plate resonance, and the wooden back panel resonance.

Reducing Mission Logistics with Multipurpose Cargo Transfer Bags

NASA Technical Reports Server (NTRS)

Baccus, Shelley; Broyan, James Lee, Jr.; Borrego, Melissa

2016-01-01

The Logistics Reduction (LR) project within Advanced Exploration Systems (AES) is tasked with reducing logistical mass and repurposing logistical items. Multipurpose Cargo Transfer Bags (MCTB) have been designed such that they can serve the same purpose as a Cargo Transfer Bag (CTB), the common logistics carrying bag for the International Space Station (ISS). After use as a cargo carrier, a regular CTB becomes trash, whereas the MCTB can be unfolded into a flat panel for reuse. Concepts and potential benefits for various MCTB applications will be discussed including partitions, crew quarters, solar radiation storm shelters, acoustic blankets, and forward osmosis water processing. Acoustic MCTBs are currently in use on ISS to reduce the noise generated by the T2 treadmill, which reaches the hazard limit at high speeds. The development of the AMCTB included identification of keep-out zones, acoustic properties, deployment considerations, and structural testing. Features developed for these considerations are applicable to MCTBs for all crew outfitting applications.

Multipurpose Cargo Transfer Bags fro Reducing Exploration Mission Logistics

NASA Technical Reports Server (NTRS)

Baccus, Shelley; Broyan, James Lee, Jr.; Borrego, Melissa

2016-01-01

The Logistics Reduction (LR) project within the Advanced Exploration Systems (AES) division is tasked with reducing logistical mass and repurposing logistical items. Multipurpose Cargo Transfer Bags (MCTB) have been designed such that they can serve the same purpose as a Cargo Transfer Bag (CTB), the common logistics carrying bag for the International Space Station (ISS). After use as a cargo carrier, a regular CTB becomes trash, whereas the MCTB can be unfolded into a flat panel for reuse. Concepts and potential benefits for various MCTB applications will be discussed including partitions, crew quarters, solar radiation storm shelters, acoustic blankets, and forward osmosis water processing. Acoustic MCTBs are currently in use on ISS to reduce the noise generated by the T2 treadmill, which reaches the hazard limit at high speeds. The development of the AMCTB included identification of keep out zones, acoustic properties, deployment considerations, and structural testing. Features developed for these considerations are applicable to MCTBs for all crew outfitting applications.

Application of acoustic surface wave filter-beam lead component technology to deep space multimission hardware design

NASA Technical Reports Server (NTRS)

Kermode, A. W.; Boreham, J. F.

1974-01-01

This paper discusses the utilization of acoustic surface wave filters, beam lead components, and thin film metallized ceramic substrate technology as applied to the design of deep space, long-life, multimission transponder. The specific design to be presented is for a second mixer local oscillator module, operating at frequencies as high as 249 MHz.

Urban spaces adopted by the performing arts

NASA Astrophysics Data System (ADS)

Case, Alexander U.

2004-05-01

No celebration of acoustics in New York City would be complete without mention of the countless alternative spaces used for the perfor- mance of music, dance, and other art forms. New York's countless train stations, parks, alleys, and overpasses provide popular venues for artists to make sound. Lincoln Center and Carnegie get all the glory, but it's the streets and train stations that do all the work. This work surveys some of these alternative performance spaces and their acoustic contribution to the performance.

On the acoustics of ancient Greek and Roman theaters.

PubMed

Farnetani, Andrea; Prodi, Nicola; Pompoli, Roberto

2008-09-01

The interplay of architecture and acoustics is remarkable in ancient Greek and Roman theaters. Frequently they are nowadays lively performance spaces and the knowledge of the sound field inside them is still an issue of relevant importance. Even if the transition from Greek to Roman theaters can be described with a great architectural detail, a comprehensive and objective approach to the two types of spaces from the acoustical point of view is available at present only as a computer model study [P. Chourmouziadou and J. Kang, "Acoustic evolution of ancient Greek and Roman theaters," Appl. Acoust. 69, re (2007)]. This work addresses the same topic from the experimental point of view, and its aim is to provide a basis to the acoustical evolution from Greek to Roman theater design. First, by means of in situ and scale model measurements, the most important features of the sound field in ancient theaters are clarified and discussed. Then it has been possible to match quantitatively the role of some remarkable architectural design variables with acoustics, and it is seen how this criterion can be used effectively to define different groups of ancient theaters. Finally some more specific wave phenomena are addressed and discussed.

Numerical investigation of implementation of air-earth boundary by acoustic-elastic boundary approach

USGS Publications Warehouse

Xu, Y.; Xia, J.; Miller, R.D.

2007-01-01

The need for incorporating the traction-free condition at the air-earth boundary for finite-difference modeling of seismic wave propagation has been discussed widely. A new implementation has been developed for simulating elastic wave propagation in which the free-surface condition is replaced by an explicit acoustic-elastic boundary. Detailed comparisons of seismograms with different implementations for the air-earth boundary were undertaken using the (2,2) (the finite-difference operators are second order in time and space) and the (2,6) (second order in time and sixth order in space) standard staggered-grid (SSG) schemes. Methods used in these comparisons to define the air-earth boundary included the stress image method (SIM), the heterogeneous approach, the scheme of modifying material properties based on transversely isotropic medium approach, the acoustic-elastic boundary approach, and an analytical approach. The method proposed achieves the same or higher accuracy of modeled body waves relative to the SIM. Rayleigh waves calculated using the explicit acoustic-elastic boundary approach differ slightly from those calculated using the SIM. Numerical results indicate that when using the (2,2) SSG scheme for SIM and our new method, a spatial step of 16 points per minimum wavelength is sufficient to achieve 90% accuracy; 32 points per minimum wavelength achieves 95% accuracy in modeled Rayleigh waves. When using the (2,6) SSG scheme for the two methods, a spatial step of eight points per minimum wavelength achieves 95% accuracy in modeled Rayleigh waves. Our proposed method is physically reasonable and, based on dispersive analysis of simulated seismographs from a layered half-space model, is highly accurate. As a bonus, our proposed method is easy to program and slightly faster than the SIM. ?? 2007 Society of Exploration Geophysicists.

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

PubMed

Chen, Di; Wu, Junru

2010-01-01

It is known that there are many fine particles on the moon and Mars. Their existence may cause risk for the success of a long-term project for NASA, i.e., exploration and habitation of the moon and Mars. These dust-particles might cover the solar panels, making them fail to generate electricity, and they might also penetrate through seals on space suits, hatches, and vehicle wheels causing many incidents. The fine particles would be hazardous to human health if they were inhaled. Development of robust dust mitigation technology is urgently needed for the viable long-term exploration and habilitation of either the moon or Mars. A feasibility study to develop a dust removal technique, which may be used in space-stations or other enclosures for habitation, is reported. It is shown experimentally that the acoustic radiation force produced by a 13.8 kHz 128 dB sound-level standing wave between a 3 cm-aperture tweeter and a reflector separated by 9 cm is strong enough to overcome the van der Waals adhesive force between the dust-particles and the reflector-surface. Thus the majority of fine particles (>2 microm diameter) on a reflector-surface can be dislodged and removed by a technique combining acoustic levitation and airflow methods. The removal efficiency deteriorates for particles of less than 2 microm in size.

Development of the Space Debris Sensor (SDS)

NASA Technical Reports Server (NTRS)

Hamilton, J.; Liou, J.-C.; Anz-Meador, P. D.; Corsaro, B.; Giovane, F.; Matney, M.; Christiansen, E.

2017-01-01

The Space Debris Sensor (SDS) is a NASA experiment scheduled to fly aboard the International Space Station (ISS) starting in 2018. The SDS is the first flight demonstration of the Debris Resistive/Acoustic Grid Orbital NASA-Navy Sensor (DRAGONS) developed and matured at NASA Johnson Space Center's Orbital Debris Program Office. The DRAGONS concept combines several technologies to characterize the size, speed, direction, and density of small impacting objects. With a minimum two-year operational lifetime, SDS is anticipated to collect statistically significant information on orbital debris ranging from 50 microns to 500 microns in size. This paper describes the features of SDS and how data from the ISS mission may be used to update debris environment models. Results of hypervelocity impact testing during the development of SDS and the potential for improvement on future sensors at higher altitudes will be reviewed.

Manipulation of Liquids Using Phased Array Generation of Acoustic Radiation Pressure

NASA Technical Reports Server (NTRS)

Oeftering, Richard C. (Inventor)

2000-01-01

A phased array of piezoelectric transducers is used to control and manipulate contained as well as uncontained fluids in space and earth applications. The transducers in the phased array are individually activated while being commonly controlled to produce acoustic radiation pressure and acoustic streaming. The phased array is activated to produce a single pulse, a pulse burst or a continuous pulse to agitate, segregate or manipulate liquids and gases. The phased array generated acoustic radiation pressure is also useful in manipulating a drop, a bubble or other object immersed in a liquid. The transducers can be arranged in any number of layouts including linear single or multi- dimensional, space curved and annular arrays. The individual transducers in the array are activated by a controller, preferably driven by a computer.

LIDAR and acoustics applications to ocean productivity

NASA Technical Reports Server (NTRS)

Collins, D. J.

1982-01-01

The requirements for the submersible, the instrumentation necessary to perform these measurements, and the optical and acoustical technology required to develop the ocean color scanner instrumentation are described. The development of a second generation ocean color scanner produced the need for coincident in situ scientific measurements which examine the primary productivity of the upper ocean on time and space scales which are large compared to the environmental scales. The vertical and horizontal variability of the biota, including the relationship between chlorophyll and primary productivity, the productivity of zooplankton, and the dynamic interaction between phytoplankton and zooplankton, and between these populations and the physical environment are investigated. A towed submersible will be constructed which accommodates both an underwater LIDAR instrument and a multifrequency sonar.

KSC-03PD-2383

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin monitor some of the project's equipment just released into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2380

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepare to release some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2385

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin lifts some of the project's equipment from the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2382

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin releases some of the project's equipment into the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2378

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. A research team member aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin prepares some of the project's equipment for placement in the water. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

KSC-03PD-2386

NASA Technical Reports Server (NTRS)

2003-01-01

KENNEDY SPACE CENTER, FLA. Research team members aboard one of the watercraft being utilized to conduct underwater acoustic research in the Launch Complex 39 turn basin secure some of the project's equipment back into the vessel. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASAs Jet Propulsion Laboratory, and mobile robotic sensors from the Navys Mobile Diving and Salvage Unit.

The effect of reduced vowel working space on speech intelligibility in Mandarin-speaking young adults with cerebral palsy

NASA Astrophysics Data System (ADS)

Liu, Huei-Mei; Tsao, Feng-Ming; Kuhl, Patricia K.

2005-06-01

The purpose of this study was to examine the effect of reduced vowel working space on dysarthric talkers' speech intelligibility using both acoustic and perceptual approaches. In experiment 1, the acoustic-perceptual relationship between vowel working space area and speech intelligibility was examined in Mandarin-speaking young adults with cerebral palsy. Subjects read aloud 18 bisyllabic words containing the vowels /eye/, /aye/, and /you/ using their normal speaking rate. Each talker's words were identified by three normal listeners. The percentage of correct vowel and word identification were calculated as vowel intelligibility and word intelligibility, respectively. Results revealed that talkers with cerebral palsy exhibited smaller vowel working space areas compared to ten age-matched controls. The vowel working space area was significantly correlated with vowel intelligibility (r=0.632, p<0.005) and with word intelligibility (r=0.684, p<0.005). Experiment 2 examined whether tokens of expanded vowel working spaces were perceived as better vowel exemplars and represented with greater perceptual spaces than tokens of reduced vowel working spaces. The results of the perceptual experiment support this prediction. The distorted vowels of talkers with cerebral palsy compose a smaller acoustic space that results in shrunken intervowel perceptual distances for listeners. .

Adverse event detection (AED) system for continuously monitoring and evaluating structural health status

NASA Astrophysics Data System (ADS)

Yun, Jinsik; Ha, Dong Sam; Inman, Daniel J.; Owen, Robert B.

2011-03-01

Structural damage for spacecraft is mainly due to impacts such as collision of meteorites or space debris. We present a structural health monitoring (SHM) system for space applications, named Adverse Event Detection (AED), which integrates an acoustic sensor, an impedance-based SHM system, and a Lamb wave SHM system. With these three health-monitoring methods in place, we can determine the presence, location, and severity of damage. An acoustic sensor continuously monitors acoustic events, while the impedance-based and Lamb wave SHM systems are in sleep mode. If an acoustic sensor detects an impact, it activates the impedance-based SHM. The impedance-based system determines if the impact incurred damage. When damage is detected, it activates the Lamb wave SHM system to determine the severity and location of the damage. Further, since an acoustic sensor dissipates much less power than the two SHM systems and the two systems are activated only when there is an acoustic event, our system reduces overall power dissipation significantly. Our prototype system demonstrates the feasibility of the proposed concept.

Artillery/mortar round type classification to increase system situational awareness

NASA Astrophysics Data System (ADS)

Desai, Sachi; Grasing, David; Morcos, Amir; Hohil, Myron

2008-04-01

Feature extraction methods based on the statistical analysis of the change in event pressure levels over a period and the level of ambient pressure excitation facilitate the development of a robust classification algorithm. The features reliably discriminates mortar and artillery variants via acoustic signals produced during the launch events. Utilizing acoustic sensors to exploit the sound waveform generated from the blast for the identification of mortar and artillery variants as type A, etcetera through analysis of the waveform. Distinct characteristics arise within the different mortar/artillery variants because varying HE mortar payloads and related charges emphasize varying size events at launch. The waveform holds various harmonic properties distinct to a given mortar/artillery variant that through advanced signal processing and data mining techniques can employed to classify a given type. The skewness and other statistical processing techniques are used to extract the predominant components from the acoustic signatures at ranges exceeding 3000m. Exploiting these techniques will help develop a feature set highly independent of range, providing discrimination based on acoustic elements of the blast wave. Highly reliable discrimination will be achieved with a feedforward neural network classifier trained on a feature space derived from the distribution of statistical coefficients, frequency spectrum, and higher frequency details found within different energy bands. The processes that are described herein extend current technologies, which emphasis acoustic sensor systems to provide such situational awareness.

Tutorial on the Psychophysics and Technology of Virtual Acoustic Displays

NASA Technical Reports Server (NTRS)

Wenzel, Elizabeth M.; Null, Cynthia (Technical Monitor)

1998-01-01

Virtual acoustics, also known as 3-D sound and auralization, is the simulation of the complex acoustic field experienced by a listener within an environment. Going beyond the simple intensity panning of normal stereo techniques, the goal is to process sounds so that they appear to come from particular locations in three-dimensional space. Although loudspeaker systems are being developed, most of the recent work focuses on using headphones for playback and is the outgrowth of earlier analog techniques. For example, in binaural recording, the sound of an orchestra playing classical music is recorded through small mics in the two "ear canals" of an anthropomorphic artificial or "dummy" head placed in the audience of a concert hall. When the recorded piece is played back over headphones, the listener passively experiences the illusion of hearing the violins on the left and the cellos on the right, along with all the associated echoes, resonances, and ambience of the original environment. Current techniques use digital signal processing to synthesize the acoustical properties that people use to localize a sound source in space. Thus, they provide the flexibility of a kind of digital dummy head, allowing a more active experience in which a listener can both design and move around or interact with a simulated acoustic environment in real time. Such simulations are being developed for a variety of application areas including architectural acoustics, advanced human-computer interfaces, telepresence and virtual reality, navigation aids for the visually-impaired, and as a test bed for psychoacoustical investigations of complex spatial cues. The tutorial will review the basic psychoacoustical cues that determine human sound localization and the techniques used to measure these cues as Head-Related Transfer Functions (HRTFs) for the purpose of synthesizing virtual acoustic environments. The only conclusive test of the adequacy of such simulations is an operational one in which the localization of real and synthesized stimuli are directly compared in psychophysical studies. To this end, the results of psychophysical experiments examining the perceptual validity of the synthesis technique will be reviewed and factors that can enhance perceptual accuracy and realism will be discussed. Of particular interest is the relationship between individual differences in HRTFs and in behavior, the role of reverberant cues in reducing the perceptual errors observed with virtual sound sources, and the importance of developing perceptually valid methods of simplifying the synthesis technique. Recent attempts to implement the synthesis technique in real time systems will also be discussed and an attempt made to interpret their quoted system specifications in terms of perceptual performance. Finally, some critical research and technology development issues for the future will be outlined.

Electrochemical Processes Enhanced by Acoustic Liquid Manipulation

NASA Technical Reports Server (NTRS)

Oeftering, Richard C.

2004-01-01

Acoustic liquid manipulation is a family of techniques that employ the nonlinear acoustic effects of acoustic radiation pressure and acoustic streaming to manipulate the behavior of liquids. Researchers at the NASA Glenn Research Center are exploring new methods of manipulating liquids for a variety of space applications, and we have found that acoustic techniques may also be used in the normal Earth gravity environment to enhance the performance of existing fluid processes. Working in concert with the NASA Commercial Technology Office, the Great Lakes Industrial Technology Center, and Alchemitron Corporation (Elgin, IL), researchers at Glenn have applied nonlinear acoustic principles to industrial applications. Collaborating with Alchemitron Corporation, we have adapted the devices to create acoustic streaming in a conventional electroplating process.

Acoustic levitation methods for density measurements

NASA Technical Reports Server (NTRS)

Trinh, E. H.; Hsu, C. J.

1986-01-01

The capability of ultrasonic levitators operating in air to perform density measurements has been demonstrated. The remote determination of the density of ordinary liquids as well as low density solid metals can be carried out using levitated samples with size on the order of a few millimeters and at a frequency of 20 kHz. Two basic methods may be used. The first one is derived from a previously known technique developed for acoustic levitation in liquid media, and is based on the static equilibrium position of levitated samples in the earth's gravitational field. The second approach relies on the dynamic interaction between a levitated sample and the acoustic field. The first technique appears more accurate (1 percent uncertainty), but the latter method is directly applicable to a near gravity-free environment such as that found in space.

Translation of an Object Using Phase-Controlled Sound Sources in Acoustic Levitation

NASA Astrophysics Data System (ADS)

Matsui, Takayasu; Ohdaira, Etsuzo; Masuzawa, Nobuyoshi; Ide, Masao

1995-05-01

Acoustic levitation is used for positioning materials in the development of new materials in space where there is no gravity. This technique is applicable to materials for which electromagnetic force cannot be used. If the levitation point of the materials can be controlled freely in this application, possibilities of new applications will be extended. In this paper we report on an experimental study on controlling the levitation point of the object in an acoustic levitation system. The system fabricated and tested in this study has two sound sources with vibrating plates facing each other. Translation of the object can be achieved by controlling the phase of the energizing electrical signal for one of the sound sources. It was found that the levitation point can be moved smoothly in proportion to the phase difference between the vibrating plates.

Modal analysis and dynamic stresses for acoustically excited Shuttle insulation tiles

NASA Technical Reports Server (NTRS)

Ojalvo, I. U.; Ogilvie, P. I.

1976-01-01

The thermal protection system of the Space Shuttle consists of thousands of separate insulation tiles, of varying thicknesses, bonded to the orbiter's surface through a soft strain-isolation pad which is bonded, in turn, to the vehicle's stiffened metallic skin. A modal procedure for obtaining the acoustically induced RMS stress in these comparatively thick tiles is described. The modes employed are generated by a previously developed iterative procedure which converges rapidly for the combined system of tiles and primary structure considered. Each tile is idealized by several hundred three-dimensional finite elements and all tiles on a given panel interact dynamically. Acoustic response results from the present analyses are presented. Comparisons with other analytical results and measured modal data for a typical Shuttle panel, both with and without tiles, are made, and the agreement is good.

Aeroacoustics of Space Vehicles

NASA Technical Reports Server (NTRS)

Panda, Jayanta

2014-01-01

While for airplanes the subject of aeroacoustics is associated with community noise, for space vehicles it is associated with vibro-acoustics and structural dynamics. Surface pressure fluctuations encountered during launch and travel through lower part of the atmosphere create intense vibro-acoustics environment for the payload, electronics, navigational equipment, and a large number of subsystems. All of these components have to be designed and tested for flight-certification. This presentation will cover all three major sources encountered in manned and unmanned space vehicles: launch acoustics, ascent acoustics and abort acoustics. Launch pads employ elaborate acoustic suppression systems to mitigate the ignition pressure waves and rocket plume generated noise during the early part of the liftoff. Recently we have used large microphone arrays to identify the noise sources during liftoff and found that the standard model by Eldred and Jones (NASA SP-8072) to be grossly inadequate. As the vehicle speeds up and reaches transonic speed in relatively denser part of the atmosphere, various shock waves and flow separation events create unsteady pressure fluctuations that can lead to high vibration environment, and occasional coupling with the structural modes, which may lead to buffet. Examples of wind tunnel tests and computational simulations to optimize the outer mold line to quantify and reduce the surface pressure fluctuations will be presented. Finally, a manned space vehicle needs to be designed for crew safety during malfunctioning of the primary rocket vehicle. This brings the subject of acoustic environment during abort. For NASAs Multi-Purpose Crew Vehicle (MPCV), abort will be performed by lighting rocket motors atop the crew module. The severe aeroacoustics environments during various abort scenarios were measured for the first time by using hot helium to simulate rocket plumes in the Ames unitary plan wind tunnels. Various considerations used for the helium simulation and the final confirmation from a flight test will be presented.

Application of the Molecular Adsorber Coating Technology on the Ionospheric Connection Explorer Program

NASA Technical Reports Server (NTRS)

Abraham, Nithin S.; Hasegawa, Mark M.; Secunda, Mark S.

2016-01-01

The Molecular Adsorber Coating (MAC) is a zeolite based highly porous coating technology that was developed by NASA Goddard Space Flight Center (GSFC) to capture outgassed contaminants, such as plastics, adhesives, lubricants, silicones, epoxies, potting compounds, and other similar materials. This paper describes the use of the MAC technology to address molecular contamination concerns on NASAs Ionospheric Connection Explorer (ICON) program led by the University of California (UC) Berkeleys Space Sciences Laboratory. The sprayable paint technology was applied onto plates that were installed within the instrument cavity of ICONs Far Ultraviolet Imaging Spectrograph (FUV). However, due to the instruments particulate sensitivity, the coating surface was vibrationally cleaned through simulated acoustics to reduce the risk of particle fall-out contamination. This paper summarizes the coating application efforts on the FUV adsorber plates, the simulated laboratory acoustic level cleaning test methods, particulation characteristics, and future plans for the MAC technology.

Application of the Molecular Adsorber Coating technology on the Ionospheric Connection Explorer program

NASA Astrophysics Data System (ADS)

Abraham, Nithin S.; Hasegawa, Mark M.; Secunda, Mark S.

2016-09-01

The Molecular Adsorber Coating (MAC) is a zeolite based highly porous coating technology that was developed by NASA Goddard Space Flight Center (GSFC) to capture outgassed contaminants, such as plastics, adhesives, lubricants, silicones, epoxies, potting compounds, and other similar materials. This paper describes the use of the MAC technology to address molecular contamination concerns on NASA's Ionospheric Connection Explorer (ICON) program led by the University of California (UC) Berkeley's Space Sciences Laboratory. The sprayable paint technology was applied onto plates that were installed within the instrument cavity of ICON's Far Ultraviolet Imaging Spectrograph (FUV). However, due to the instrument's particulate sensitivity, the coating surface was vibrationally cleaned through simulated acoustics to reduce the risk of particle fall-out contamination. This paper summarizes the coating application efforts on the FUV adsorber plates, the simulated laboratory acoustic level cleaning test methods, particulation characteristics, and future plans for the MAC technology.

Acoustics Research of Propulsion Systems

NASA Technical Reports Server (NTRS)

Gao, Ximing; Houston, Janice D.

2014-01-01

The liftoff phase induces some of the highest acoustic loading over a broad frequency for a launch vehicle. These external acoustic environments are used in the prediction of the internal vibration responses of the vehicle and components. Thus, predicting these liftoff acoustic environments is critical to the design requirements of any launch vehicle but there are challenges. Present liftoff vehicle acoustic environment prediction methods utilize stationary data from previously conducted hold-down tests; i.e. static firings conducted in the 1960's, to generate 1/3 octave band Sound Pressure Level (SPL) spectra. These data sets are used to predict the liftoff acoustic environments for launch vehicles. To facilitate the accuracy and quality of acoustic loading, predictions at liftoff for future launch vehicles such as the Space Launch System (SLS), non-stationary flight data from the Ares I-X were processed in PC-Signal in two forms which included a simulated hold-down phase and the entire launch phase. In conjunction, the Prediction of Acoustic Vehicle Environments (PAVE) program was developed in MATLAB to allow for efficient predictions of sound pressure levels (SPLs) as a function of station number along the vehicle using semiempirical methods. This consisted, initially, of generating the Dimensionless Spectrum Function (DSF) and Dimensionless Source Location (DSL) curves from the Ares I-X flight data. These are then used in the MATLAB program to generate the 1/3 octave band SPL spectra. Concluding results show major differences in SPLs between the hold-down test data and the processed Ares IX flight data making the Ares I-X flight data more practical for future vehicle acoustic environment predictions.

SLS Scale Model Acoustic Test Liftoff Results and Comparisons

NASA Technical Reports Server (NTRS)

Houston, Janice; Counter, Douglas; Giacomoni, Clothilde

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 design phase 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.

An Acoustic Analysis of the Vowel Space in Young and Old Cochlear-Implant Speakers

ERIC Educational Resources Information Center

Neumeyer, Veronika; Harrington, Jonathan; Draxler, Christoph

2010-01-01

The main purpose of this study was to compare acoustically the vowel spaces of two groups of cochlear implantees (CI) with two age-matched normal hearing groups. Five young test persons (15-25 years) and five older test persons (55-70 years) with CI and two control groups of the same age with normal hearing were recorded. The speech material…

Lagrangian or Eulerian; real or Fourier? Not all approaches to large-scale structure are created equal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tassev, Svetlin, E-mail: tassev@astro.princeton.edu

We present a pedagogical systematic investigation of the accuracy of Eulerian and Lagrangian perturbation theories of large-scale structure. We show that significant differences exist between them especially when trying to model the Baryon Acoustic Oscillations (BAO). We find that the best available model of the BAO in real space is the Zel'dovich Approximation (ZA), giving an accuracy of ∼<3% at redshift of z = 0 in modelling the matter 2-pt function around the acoustic peak. All corrections to the ZA around the BAO scale are perfectly perturbative in real space. Any attempt to achieve better precision requires calibrating the theorymore » to simulations because of the need to renormalize those corrections. In contrast, theories which do not fully preserve the ZA as their solution, receive O(1) corrections around the acoustic peak in real space at z = 0, and are thus of suspicious convergence at low redshift around the BAO. As an example, we find that a similar accuracy of 3% for the acoustic peak is achieved by Eulerian Standard Perturbation Theory (SPT) at linear order only at z ≈ 4. Thus even when SPT is perturbative, one needs to include loop corrections for z∼<4 in real space. In Fourier space, all models perform similarly, and are controlled by the overdensity amplitude, thus recovering standard results. However, that comes at a price. Real space cleanly separates the BAO signal from non-linear dynamics. In contrast, Fourier space mixes signal from short mildly non-linear scales with the linear signal from the BAO to the level that non-linear contributions from short scales dominate. Therefore, one has little hope in constructing a systematic theory for the BAO in Fourier space.« less

Development and applications of nondestructive evaluation at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Whitaker, Ann F.

1990-01-01

A brief description of facility design and equipment, facility usage, and typical investigations are presented for the following: Surface Inspection Facility; Advanced Computer Tomography Inspection Station (ACTIS); NDE Data Evaluation Facility; Thermographic Test Development Facility; Radiographic Test Facility; Realtime Radiographic Test Facility; Eddy Current Research Facility; Acoustic Emission Monitoring System; Advanced Ultrasonic Test Station (AUTS); Ultrasonic Test Facility; and Computer Controlled Scanning (CONSCAN) System.

Acoustic resonances in cylinder bundles oscillating in a compressibile fluid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, W.H.; Raptis, A.C.

1984-12-01

This paper deals with an analytical study on acoustic resonances of elastic oscillations of a group of parallel, circular, thin cylinders in an unbounded volume of barotropic, compressible, inviscid fluid. The perturbed motion of the fluid is assumed due entirely to the flexural oscillations of the cylinders. The motion of the fluid disturbances is first formulated in a three-dimensional wave form and then casted into a two-dimensional Helmholtz equation for the harmonic motion in time and in axial space. The acoustic motion in the fluid and the elastic motion in the cylinders are solved simultaneously. Acoustic resonances were approximately determinedmore » from the secular (eigenvalue) equation by the method of successive iteration with the use of digital computers for a given set of the fluid properties and the cylinders' geometry and properties. Effects of the flexural wavenumber and the configuration of and the spacing between the cylinders on the acoustic resonances were thoroughly investigated.« less

Coordinated Control of Acoustical Field of View and Flight in Three-Dimensional Space for Consecutive Capture by Echolocating Bats during Natural Foraging.

PubMed

Sumiya, Miwa; Fujioka, Emyo; Motoi, Kazuya; Kondo, Masaru; Hiryu, Shizuko

2017-01-01

Echolocating bats prey upon small moving insects in the dark using sophisticated sonar techniques. The direction and directivity pattern of the ultrasound broadcast of these bats are important factors that affect their acoustical field of view, allowing us to investigate how the bats control their acoustic attention (pulse direction) for advanced flight maneuvers. The purpose of this study was to understand the behavioral strategies of acoustical sensing of wild Japanese house bats Pipistrellus abramus in three-dimensional (3D) space during consecutive capture flights. The results showed that when the bats successively captured multiple airborne insects in short time intervals (less than 1.5 s), they maintained not only the immediate prey but also the subsequent one simultaneously within the beam widths of the emitted pulses in both horizontal and vertical planes before capturing the immediate one. This suggests that echolocating bats maintain multiple prey within their acoustical field of view by a single sensing using a wide directional beam while approaching the immediate prey, instead of frequently shifting acoustic attention between multiple prey. We also numerically simulated the bats' flight trajectories when approaching two prey successively to investigate the relationship between the acoustical field of view and the prey direction for effective consecutive captures. This simulation demonstrated that acoustically viewing both the immediate and the subsequent prey simultaneously increases the success rate of capturing both prey, which is considered to be one of the basic axes of efficient route planning for consecutive capture flight. The bat's wide sonar beam can incidentally cover multiple prey while the bat forages in an area where the prey density is high. Our findings suggest that the bats then keep future targets within their acoustical field of view for effective foraging. In addition, in both the experimental results and the numerical simulations, the acoustic sensing and flights of the bats showed narrower vertical ranges than horizontal ranges. This suggests that the bats control their acoustic sensing according to different schemes in the horizontal and vertical planes according to their surroundings. These findings suggest that echolocating bats coordinate their control of the acoustical field of view and flight for consecutive captures in 3D space during natural foraging.

Coordinated Control of Acoustical Field of View and Flight in Three-Dimensional Space for Consecutive Capture by Echolocating Bats during Natural Foraging

PubMed Central

Sumiya, Miwa; Fujioka, Emyo; Motoi, Kazuya; Kondo, Masaru; Hiryu, Shizuko

2017-01-01

Echolocating bats prey upon small moving insects in the dark using sophisticated sonar techniques. The direction and directivity pattern of the ultrasound broadcast of these bats are important factors that affect their acoustical field of view, allowing us to investigate how the bats control their acoustic attention (pulse direction) for advanced flight maneuvers. The purpose of this study was to understand the behavioral strategies of acoustical sensing of wild Japanese house bats Pipistrellus abramus in three-dimensional (3D) space during consecutive capture flights. The results showed that when the bats successively captured multiple airborne insects in short time intervals (less than 1.5 s), they maintained not only the immediate prey but also the subsequent one simultaneously within the beam widths of the emitted pulses in both horizontal and vertical planes before capturing the immediate one. This suggests that echolocating bats maintain multiple prey within their acoustical field of view by a single sensing using a wide directional beam while approaching the immediate prey, instead of frequently shifting acoustic attention between multiple prey. We also numerically simulated the bats’ flight trajectories when approaching two prey successively to investigate the relationship between the acoustical field of view and the prey direction for effective consecutive captures. This simulation demonstrated that acoustically viewing both the immediate and the subsequent prey simultaneously increases the success rate of capturing both prey, which is considered to be one of the basic axes of efficient route planning for consecutive capture flight. The bat’s wide sonar beam can incidentally cover multiple prey while the bat forages in an area where the prey density is high. Our findings suggest that the bats then keep future targets within their acoustical field of view for effective foraging. In addition, in both the experimental results and the numerical simulations, the acoustic sensing and flights of the bats showed narrower vertical ranges than horizontal ranges. This suggests that the bats control their acoustic sensing according to different schemes in the horizontal and vertical planes according to their surroundings. These findings suggest that echolocating bats coordinate their control of the acoustical field of view and flight for consecutive captures in 3D space during natural foraging. PMID:28085936

Implementation of the EU Noise Directive in Process of Urban Planning in Poland

NASA Astrophysics Data System (ADS)

Kwiecień, J.; Szopińska, K.

2013-05-01

In Poland spatial planning policies are described by a system of planning documents controlled by act of Spatial Planning and Land Development of 27 March 2003. Sustainable development principle and spatial order form is the basis of spatial planning efforts. In the territory of Poland the manner of urban space management is defined by a planning document called Local Land Use Plan (LLUP). In a LLUP some issues are arranged, such as the purpose of a given area, location of public purpose investments, land development conditions. When analysing the development process of Polish cities, an obvious conclusion emerges about the lack of complex studies and researches of the environment concerning the issue of acoustic climate. The procedures of development of an LLUP involve merely a general diagnosis of an environment excluding measured values of pollution, including noise levels. The main aim of this article is to introduce the influence of acoustic climate on the urban space planning in Poland through the implementation of the provisions of Directive 2002/49/WE of the European Parliament and the Council of Europe from 25 June 2002. Moreover, in the stages of an LLUP implementations have been suggested the use of a Strategic Noise Map, being a tool for assisting the process of environmental noise level assessment in Poland.

Effects of blade-vane ratio and rotor-stator spacing of fan noise with forward velocity

NASA Astrophysics Data System (ADS)

Woodward, R. P.; Glaser, F. W.

1981-08-01

A research fan stage was acoustically tested in an anechoic wind tunnel with a 41 m/sec tunnel flow. Two stator vane numbers giving cut-on and cut-off conditions were tested at three rotor-stator spacings ranging from about 0.5 to 2.0 rotor chords. These two stators were designed for similar aerodynamic performance. Hot film anemometer turbulence measurements were made at the leading edge of the stator for each spacing. The cut-off criterion strongly controlled the fundamental tone level at all spacings. The trends with spacing of the wake defect upwash component at the stator tip showed good agreement with the corresponding cut-on acoustic tone levels.

The Effects of Inventory on Vowel Perception in French and Spanish: An MEG Study

ERIC Educational Resources Information Center

Hacquard, Valentine; Walter, Mary Ann; Marantz, Alec

2007-01-01

Production studies have shown that speakers of languages with larger phoneme inventories expand their acoustic space relative to languages with smaller inventories [Bradlow, A. (1995). A comparative acoustic study of English and Spanish vowels. "Journal of the Acoustical Society of America," 97(3), 1916-1924; Jongman, A., Fourakis, M., & Sereno,…

Synchronized LES for acoustic near-field analysis of a supersonic jet

NASA Astrophysics Data System (ADS)

S, Unnikrishnan; Gaitonde, Datta; The Ohio State University Team

2014-11-01

We develop a novel method using simultaneous, synchronized Large Eddy Simulations (LES) to examine the manner in which the plume of a supersonic jet generates the near acoustic field. Starting from a statistically stationary state, at each time-step, the first LES (Baseline) is used to obtain native perturbations, which are then localized in space, scaled to small values and injected into the second LES (Twin). At any subsequent time, the difference between the two simulations can be processed to discern how disturbances from any particular zone in the jet are modulated and filtered by the non-linear core to form the combined hydrodynamic and acoustic near field and the fully acoustic farfield. Unlike inverse techniques that use correlations between jet turbulence and far-field signals to infer causality, the current forward analysis effectively tags and tracks native perturbations as they are processed by the jet. Results are presented for a Mach 1.3 cold jet. Statistical analysis of the baseline and perturbation boost provides insight into different mechanisms of disturbance propagation, amplification, directivity, generation of intermittent wave-packet like events and the direct and indirect effect of different parts of the jet on the acoustic field. Office of Naval Research.

Acoustic Quality Levels of Mosques in Batu Pahat

NASA Astrophysics Data System (ADS)

Azizah Adnan, Nor; Nafida Raja Shahminan, Raja; Khair Ibrahim, Fawazul; Tami, Hannifah; Yusuff, M. Rizal M.; Murniwaty Samsudin, Emedya; Ismail, Isham

2018-04-01

Every Friday, Muslims has been required to perform a special prayer known as the Friday prayers which involve the delivery of a brief lecture (Khutbah). Speech intelligibility in oral communications presented by the preacher affected all the congregation and determined the level of acoustic quality in the interior of the mosque. Therefore, this study intended to assess the level of acoustic quality of three public mosques in Batu Pahat. Good acoustic quality is essential in contributing towards appreciation in prayers and increasing khusyu’ during the worship, which is closely related to the speech intelligibility corresponding to the actual function of the mosque according to Islam. Acoustic parameters measured includes noise criteria (NC), reverberation time (RT) and speech transmission index (STI), and was performed using the sound level meter and sound measurement instruments. This test is carried out through the physical observation with the consideration of space and volume design as a factor affecting acoustic parameters. Results from all 3 mosques as the showed that the acoustic quality level inside these buildings are slightly poor which is at below 0.45 coefficients based on the standard. Among the factors that influencing the low acoustical quality are location, building materials, installation of sound absorption material and the number of occupants inside the mosque. As conclusion, the acoustic quality level of a mosque is highly depends on physical factors of the mosque such as the architectural design and space volume besides other factors as been identified by this study.

Acoustics of native-American ceremonial sites in prehispanic America (Acustica en los espacios escenios rituales prehispanicos)

NASA Astrophysics Data System (ADS)

Martinez, Maria Isabel

2003-11-01

This thesis establishes a methodology that incorporates the latest procedures used in architectural acoustics for the study of open spaces of this general type, and definitions are given for the acoustic variables of interest. The ``Juego de Pelota'' (ball game) sites are the only ceremonial sites built specifically for the performance of a fertility ritual, and are ideal for the study of prehispanic architectural topographies. Analysis of the acoustic properties of such sites revealed that the topographical characteristics of the elevation profiles of these architectural structures determine the acoustic behavior of these spaces. Such profiles are classified into three basic types: (i) inclined profile, (ii) terraced profile, and (iii) mixed profile. The terraced profiles are the most efficient, and the mixed profiles are the least efficient, in regard to acoustics. The consideration of the acoustic behavior of architectural structures intended for the ``Ball Game,'' as the designs evolved over time, leads to the conclusion that acoustical sensations that contributed effectively to the characteristic mystical atmosphere of the ceremonial rituals were characteristic only of those sites constructed in the ``classical'' period. Thesis advisors: Jaime Navarro and Juan J. Sendra Copies of this thesis written in Spanish may be obtained by contacting the advisor, Jaime Navarro, E.T.S. de Arquitectura de Sevilla, Dpto. de Construcciones Arquitectonicas I, Av. Reina Mercedes, 2, 41012 Sevilla, Spain. E-mail address: jnavarro@us.es

International Space Station Acoustics - A Status Report

NASA Technical Reports Server (NTRS)

Allen, Christopher S.

2015-01-01

It is important to control acoustic noise aboard the International Space Station (ISS) to provide a satisfactory environment for voice communications, crew productivity, alarm audibility, and restful sleep, and to minimize the risk for temporary and permanent hearing loss. Acoustic monitoring is an important part of the noise control process on ISS, providing critical data for trend analysis, noise exposure analysis, validation of acoustic analyses and predictions, and to provide strong evidence for ensuring crew health and safety, thus allowing Flight Certification. To this purpose, sound level meter (SLM) measurements and acoustic noise dosimetry are routinely performed. And since the primary noise sources on ISS include the environmental control and life support system (fans and airflow) and active thermal control system (pumps and water flow), acoustic monitoring will reveal changes in hardware noise emissions that may indicate system degradation or performance issues. This paper provides the current acoustic levels in the ISS modules and sleep stations and is an update to the status presented in 2011. Since this last status report, many payloads (science experiment hardware) have been added and a significant number of quiet ventilation fans have replaced noisier fans in the Russian Segment. Also, noise mitigation efforts are planned to reduce the noise levels of the T2 treadmill and levels in Node 3, in general. As a result, the acoustic levels on the ISS continue to improve.

Method for determining waveguide temperature for acoustic transceiver used in a gas turbine engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeSilva, Upul P.; Claussen, Heiko; Ragunathan, Karthik

A method for determining waveguide temperature for at least one waveguide of a transceiver utilized for generating a temperature map. The transceiver generates an acoustic signal that travels through a measurement space in a hot gas flow path defined by a wall such as in a combustor. The method includes calculating a total time of flight for the acoustic signal and subtracting a waveguide travel time from the total time of flight to obtain a measurement space travel time. A temperature map is calculated based on the measurement space travel time. An estimated wall temperature is obtained from the temperaturemore » map. An estimated waveguide temperature is then calculated based on the estimated wall temperature wherein the estimated waveguide temperature is determined without the use of a temperature sensing device.« less

The use of a digital computer for calculation of acoustic fields of complex vibrating structures by the reciprocity principle

NASA Technical Reports Server (NTRS)

Rimskiy-Korsakov, A. V.; Belousov, Y. I.

1973-01-01

A program was compiled for calculating acoustical pressure levels, which might be created by vibrations of complex structures (an assembly of shells and rods), under the influence of a given force, for cases when these fields cannot be measured directly. The acoustical field is determined according to transition frequency and pulse characteristics of the structure in the projection mode. Projection characteristics are equal to the reception characteristics, for vibrating systems in which the reciprocity principle holds true. Characteristics in the receiving mode are calculated on the basis of experimental data on a point pulse space velocity source (input signal) and vibration response of the structure (output signal). The space velocity of a pulse source, set at a point in space r, where it is necessary to calculate the sound field of the structure p(r,t), is determined by measurements of acoustic pressure, created by a point source at a distance R. The vibration response is measured at the point where the forces F and f exciting the system should act.

Performance of an underwater acoustic volume array using time-reversal focusing.

PubMed

Root, Joseph A; Rogers, Peter H

2002-11-01

Time reversal permits acoustic focusing and beam forming in inhomogeneous and/or high-scattering environments. A volumetric array geometry can suppress back lobes and can fit a large, powerful array of elements into small spaces, like the free-water spaces on submarines. This research investigates applying the time-reversal method to an underwater acoustic volume array. The experiments evaluate the focusing performance of a 27-element volume array when different scattering structures are present within the volume of the array. The array is arranged in a 3x3x3 cubic matrix configuration with 18.75-cm vertical and horizontal element spacing. The system utilizes second-derivative Gaussian pulses to focus on a point 30 cm from the array. Results include a comparison between time-reversal focusing and standard focusing, an evaluation of the volume array's ability to suppress back lobes, and an analysis of how different scattering environments affect focal region size. Potential underwater applications for a volume array using time reversal include acoustic imaging, naval mine hunting, sonar, and underwater communications.

Characterization of Pump-Induced Acoustics in Space Launch System Main Propulsion System Liquid Hydrogen Feedline Using Airflow Test Data

NASA Technical Reports Server (NTRS)

Eberhart, C. J.; Snellgrove, L. M.; Zoladz, T. F.

2015-01-01

High intensity acoustic edgetones located upstream of the RS-25 Low Pressure Fuel Turbo Pump (LPFTP) were previously observed during Space Launch System (STS) airflow testing of a model Main Propulsion System (MPS) liquid hydrogen (LH2) feedline mated to a modified LPFTP. MPS hardware has been adapted to mitigate the problematic edgetones as part of the Space Launch System (SLS) program. A follow-on airflow test campaign has subjected the adapted hardware to tests mimicking STS-era airflow conditions, and this manuscript describes acoustic environment identification and characterization born from the latest test results. Fluid dynamics responsible for driving discrete excitations were well reproduced using legacy hardware. The modified design was found insensitive to high intensity edgetone-like discretes over the bandwidth of interest to SLS MPS unsteady environments. Rather, the natural acoustics of the test article were observed to respond in a narrowband-random/mixed discrete manner to broadband noise thought generated by the flow field. The intensity of these responses were several orders of magnitude reduced from those driven by edgetones.

Non-auditory factors affecting urban soundscape evaluation.

PubMed

Jeon, Jin Yong; Lee, Pyoung Jik; Hong, Joo Young; Cabrera, Densil

2011-12-01

The aim of this study is to characterize urban spaces, which combine landscape, acoustics, and lighting, and to investigate people's perceptions of urban soundscapes through quantitative and qualitative analyses. A general questionnaire survey and soundwalk were performed to investigate soundscape perception in urban spaces. Non-auditory factors (visual image, day lighting, and olfactory perceptions), as well as acoustic comfort, were selected as the main contexts that affect soundscape perception, and context preferences and overall impressions were evaluated using an 11-point numerical scale. For qualitative analysis, a semantic differential test was performed in the form of a social survey, and subjects were also asked to describe their impressions during a soundwalk. The results showed that urban soundscapes can be characterized by soundmarks, and soundscape perceptions are dominated by acoustic comfort, visual images, and day lighting, whereas reverberance in urban spaces does not yield consistent preference judgments. It is posited that the subjective evaluation of reverberance can be replaced by physical measurements. The categories extracted from the qualitative analysis revealed that spatial impressions such as openness and density emerged as some of the contexts of soundscape perception. © 2011 Acoustical Society of America

Measurement and Characterization of Space Shuttle Solid Rocket Motor Plume Acoustics

NASA Technical Reports Server (NTRS)

Kenny, Jeremy; Hobbs, Chris; Plotkin, Ken; Pilkey, Debbie

2009-01-01

Lift-off acoustic environments generated by the future Ares I launch vehicle are assessed by the NASA Marshall Space Flight Center (MSFC) acoustics team using several prediction tools. This acoustic environment is directly caused by the Ares I First Stage booster, powered by the five-segment Reusable Solid Rocket Motor (RSRMV). The RSRMV is a larger-thrust derivative design from the currently used Space Shuttle solid rocket motor, the Reusable Solid Rocket Motor (RSRM). Lift-off acoustics is an integral part of the composite launch vibration environment affecting the Ares launch vehicle and must be assessed to help generate hardware qualification levels and ensure structural integrity of the vehicle during launch and lift-off. Available prediction tools that use free field noise source spectrums as a starting point for generation of lift-off acoustic environments are described in the monograph NASA SP-8072: "Acoustic Loads Generated by the Propulsion System." This monograph uses a reference database for free field noise source spectrums which consist of subscale rocket motor firings, oriented in horizontal static configurations. The phrase "subscale" is appropriate, since the thrust levels of rockets in the reference database are orders of magnitude lower than the current design thrust for the Ares launch family. Thus, extrapolation is needed to extend the various reference curves to match Ares-scale acoustic levels. This extrapolation process yields a subsequent amount of uncertainty added upon the acoustic environment predictions. As the Ares launch vehicle design schedule progresses, it is important to take every opportunity to lower prediction uncertainty and subsequently increase prediction accuracy. Never before in NASA s history has plume acoustics been measured for large scale solid rocket motors. Approximately twice a year, the RSRM prime vendor, ATK Launch Systems, static fires an assembled RSRM motor in a horizontal configuration at their test facility in Utah. The remaining RSRM static firings will take place on elevated terrain, with the nozzle exit plume being mostly undeflected and the landscape allowing placement of microphones within direct line of sight to the exhaust plume. These measurements will help assess the current extrapolation process by direct comparison between subscale and full scale solid rocket motor data.

The Shock and Vibration Bulletin. Part 1: Invited Papers, Vibrations and Acoustics, Blast and Shock

NASA Technical Reports Server (NTRS)

1979-01-01

Development in the modeling and simulation of shock and vibration phenomena are considered. Predicting the noise exposure of payloads in the space shuttle, prediction for step-stress fatigue, pyrotechnique shock simulation using metal-to-metal impact, and prediction of fragment velocities and trajectories are among the topics covered.

Cool and Quiet: Partnering to Enhance the Aerodynamic and Acoustic Performance of Installed Electronics Cooling Fans: A White Paper

NASA Technical Reports Server (NTRS)

Koch, L. Danielle; VanZante, Dale E.

2006-01-01

Breathtaking images of distant planets. Spacewalks to repair a telescope in orbit. Footprints on the moon. The awesome is made possible by the mundane. Every achievement in space exploration has relied on solid, methodical advances in engineering. Space exploration fuels economic development like no other endeavor can. But which advances will make their way into our homes and businesses? And how long will it take? Answers to these questions are dependent upon industrial involvement in government sponsored research initiatives, market demands, and timing. Recognizing an opportunity is half the battle. This proposal describes the framework for a collaborative research program aimed at improving the aerodynamic and acoustic performance of electronics cooling fans. At its best, the program would involve NASA and academic researchers, as well as corporate researchers representing the Information Technology (IT) and fan manufacturing industries. The momentum of space exploration, the expertise resultant from the nation's substantial investment in turbofan noise reduction research, and the competitiveness of the IT industry are intended to be catalysts of innovation.

Response of space shuttle insulation panels to acoustic noise pressure

NASA Technical Reports Server (NTRS)

Vaicaitis, R.

1976-01-01

The response of reusable space shuttle insulation panels to random acoustic pressure fields are studied. The basic analytical approach in formulating the governing equations of motion uses a Rayleigh-Ritz technique. The input pressure field is modeled as a stationary Gaussian random process for which the cross-spectral density function is known empirically from experimental measurements. The response calculations are performed in both frequency and time domain.

Cancellation of residual spacecraft accelerations for zero-G space physics experiments

NASA Technical Reports Server (NTRS)

Stephens, J. B.

1977-01-01

The Drop Dynamics Module houses an acoustic positioning system which counteracts the effects of small accelerations of a spacecraft and thus allows long-term study of free-floating materials such as liquid drops. The acoustic positioning system provides an acoustic 'well' in the center of the experiment chamber. Data collection is by cinematographic photography. The module subsystems are discussed.

Acoustic Seaglider: PhilSea10 Data Analysis

DTIC Science & Technology

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

Experimental Study of Sound Waves in Sandy Sediment

DTIC Science & Technology

2003-05-01

parameter model ) and measurements (using a reflection ratio technique) includes derivations and measurements of acoustic imped- ances, effective densities...22 2.9 Model Used to Find Acoustic Impedance of Biot Medium . . . . . . . . . . . . . . 24 2.10 Free Body Diagram of...38] derived the complex reflection coefficient of plane acoustic waves from a poro-elastic sediment half-space. The boundary condition model is

Acoustical case studies of three green buildings

NASA Astrophysics Data System (ADS)

Siebein, Gary; Lilkendey, Robert; Skorski, Stephen

2005-04-01

Case studies of 3 green buildings with LEED certifications that required extensive acoustical retrofit work to become satisfactory work environments for their intended user groups will be used to define areas where green building design concepts and acoustical design concepts require reconciliation. Case study 1 is an office and conference center for a city environmental education agency. Large open spaces intended to collect daylight through clerestory windows provided large, reverberant volumes with few acoustic finishes that rendered them unsuitable as open office space and a conference room/auditorium. Case Study 2 describes one of the first gold LEED buildings in the southeast whose primary design concepts were so narrowly focused on thermal and lighting issues that they often worked directly against basic acoustical requirements resulting in sound levels of NC 50-55 in classrooms and faculty offices, crosstalk between classrooms and poor room acoustics. Case study 3 is an environmental education and conference center with open public areas, very high ceilings, and all reflective surfaces made from wood and other environmentally friendly materials that result in excessive loudness when the building is used by the numbers of people which it was intended to serve.

Magnetoactive Acoustic Metamaterials.

PubMed

Yu, Kunhao; Fang, Nicholas X; Huang, Guoliang; Wang, Qiming

2018-04-11

Acoustic metamaterials with negative constitutive parameters (modulus and/or mass density) have shown great potential in diverse applications ranging from sonic cloaking, abnormal refraction and superlensing, to noise canceling. In conventional acoustic metamaterials, the negative constitutive parameters are engineered via tailored structures with fixed geometries; therefore, the relationships between constitutive parameters and acoustic frequencies are typically fixed to form a 2D phase space once the structures are fabricated. Here, by means of a model system of magnetoactive lattice structures, stimuli-responsive acoustic metamaterials are demonstrated to be able to extend the 2D phase space to 3D through rapidly and repeatedly switching signs of constitutive parameters with remote magnetic fields. It is shown for the first time that effective modulus can be reversibly switched between positive and negative within controlled frequency regimes through lattice buckling modulated by theoretically predicted magnetic fields. The magnetically triggered negative-modulus and cavity-induced negative density are integrated to achieve flexible switching between single-negative and double-negative. This strategy opens promising avenues for remote, rapid, and reversible modulation of acoustic transportation, refraction, imaging, and focusing in subwavelength regimes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analogue Transformations in Physics and their Application to Acoustics

PubMed Central

García-Meca, C.; Carloni, S.; Barceló, C.; Jannes, G.; Sánchez-Dehesa, J.; Martínez, A.

2013-01-01

Transformation optics has shaped up a revolutionary electromagnetic design paradigm, enabling scientists to build astonishing devices such as invisibility cloaks. Unfortunately, the application of transformation techniques to other branches of physics is often constrained by the structure of the field equations. We develop here a complete transformation method using the idea of analogue spacetimes. The method is general and could be considered as a new paradigm for controlling waves in different branches of physics, from acoustics in quantum fluids to graphene electronics. As an application, we derive an “analogue transformation acoustics” formalism that naturally allows the use of transformations mixing space and time or involving moving fluids, both of which were impossible with the standard approach. To demonstrate the power of our method, we give explicit designs of a dynamic compressor, a spacetime cloak for acoustic waves and a carpet cloak for a moving aircraft. PMID:23774575

Calling at the highway: The spatiotemporal constraint of road noise on Pacific chorus frog communication.

PubMed

Nelson, Danielle V; Klinck, Holger; Carbaugh-Rutland, Alexander; Mathis, Codey L; Morzillo, Anita T; Garcia, Tiffany S

2017-01-01

Loss of acoustic habitat due to anthropogenic noise is a key environmental stressor for vocal amphibian species, a taxonomic group that is experiencing global population declines. The Pacific chorus frog ( Pseudacris regilla ) is the most common vocal species of the Pacific Northwest and can occupy human-dominated habitat types, including agricultural and urban wetlands. This species is exposed to anthropogenic noise, which can interfere with vocalizations during the breeding season. We hypothesized that Pacific chorus frogs would alter the spatial and temporal structure of their breeding vocalizations in response to road noise, a widespread anthropogenic stressor. We compared Pacific chorus frog call structure and ambient road noise levels along a gradient of road noise exposures in the Willamette Valley, Oregon, USA. We used both passive acoustic monitoring and directional recordings to determine source level (i.e., amplitude or volume), dominant frequency (i.e., pitch), call duration, and call rate of individual frogs and to quantify ambient road noise levels. Pacific chorus frogs were unable to change their vocalizations to compensate for road noise. A model of the active space and time ("spatiotemporal communication") over which a Pacific chorus frog vocalization could be heard revealed that in high-noise habitats, spatiotemporal communication was drastically reduced for an individual. This may have implications for the reproductive success of this species, which relies on specific call repertoires to portray relative fitness and attract mates. Using the acoustic call parameters defined by this study (frequency, source level, call rate, and call duration), we developed a simplified model of acoustic communication space-time for this species. This model can be used in combination with models that determine the insertion loss for various acoustic barriers to define the impact of anthropogenic noise on the radius of communication in threatened species. Additionally, this model can be applied to other vocal taxonomic groups provided the necessary acoustic parameters are determined, including the frequency parameters and perception thresholds. Reduction in acoustic habitat by anthropogenic noise may emerge as a compounding environmental stressor for an already sensitive taxonomic group.

Church acoustics: A state-of-the-art review after several decades of research

NASA Astrophysics Data System (ADS)

Girón, Sara; Álvarez-Morales, Lidia; Zamarreño, Teófilo

2017-12-01

This work describes and analyses the principal contributions to the acoustics of occidental Christian churches from the second half of the last century to the present day, mainly in ancient historical churches. After more than six decades of research, it seems appropriate to summarise the major pieces of work in this field, and, to this end, this paper aims to provide an up-to-date document of all the most relevant studies which describe the exhaustive investigations of acoustic characterisation in time-consuming experimental campaigns carried out by several groups of researchers in various European countries. The article presents, for the research into church acoustics developed in each country, the experimental procedures, the results, discussions, the theoretical interpretations of the sound propagation in these spaces, the subjective aspects in the listening experience, and the method of implementation of computer simulation techniques and their applications in these complex enclosures. Other contributions from Asian and American continents are also included. Findings and advances in each of these areas as well as perspectives on their future challenges are summarized and discussed in this work.

Eavesdropping on elephants

NASA Astrophysics Data System (ADS)

Payne, Katy

2004-05-01

The Elephant Listening Project is creating an acoustic monitoring program for African forest elephants, an endangered species that lives in dense forests where visual censusing is impossible. In 2002, a 21/2-month continuous recording was made on an array of autonomous recording units (ARUs) surrounding a forest clearing in the Central African Republic. Each day between 10 and 160 forest elephants (Loxodonta cyclotis), the subjects of Andrea Turkalo's 13-year demographic study, were present on the clearing. Thousands of vocalizations were recorded, most of which contained infrasonic energy. The calls were located in space using software developed in the Bioacoustics Research Program. During daylight hours simultaneous video recordings were made. GPS time-synchronization of video cameras and the ARUs made it possible to identify the elephants responsible for many calls and to examine associated circumstances and behaviors. Recordings were also made on a second acoustic array, permitting a preliminary estimate of propagation and an indication of source level for selected elephant calls. Automatic detection of elephant calls is increasing the feasibility of analyzing long acoustic recordings, and paving the way for finer-tuned analyses, with an ultimate goal of describing forest elephants' acoustic repertoire.

Experimental results for a prototype 3-D acoustic imaging system using an ultra-sparse planar array

NASA Astrophysics Data System (ADS)

Impagliazzo, John M.; Chiang, Alice M.; Broadstone, Steven R.

2002-11-01

A handheld high resolution sonar has been under development to provide Navy Divers with a 3-D acoustic imaging system for mine reconnaissance. An ultra-sparse planar array, consisting of 121 1 mm x1 mm, 2 MHz elements, was fabricated to provide 3-D acoustic images. The array was 10 cm x10 cm. A full array at this frequency with elements at half-wavelength spacing would consist of 16384 elements. The first phase of testing of the planar array was completed in September 2001 with the characterization of the array in the NUWC Acoustic Test Facility (ATF). The center frequency was 2 MHz with a 667 kHz bandwidth. A system-level technology demonstration will be conducted in July 2002 with a real-time beamformer and near real-time 3-D imaging software. The demonstration phase consists of imaging simple targets at a range of 3 m in the ATF. Experimental results obtained will be reported on. [Work supported by the Defense Applied Research Project Agency, Advance Technology Office, Dr. Theo Kooij, Program Manager.

The design and development of an automatic control system for the in-duct cancellation of spinning modes of sound. M.S. Thesis

NASA Technical Reports Server (NTRS)

Harrington, W. W.

1973-01-01

The reduction is discussed of the discrete tones generated by jet engines which is essential for jet aircraft to meet present and proposed noise standards. The discrete tones generated by the blades and vanes propagate in the inlet and exhaust duct in the form of spiraling acoustic waves, or spinning modes. The reduction of these spinning modes by the cancellation effect of the combination of two acoustic fields was investigated. The spinning mode synthesizer provided the means for effective study of this noise reduction scheme. Two sets of electrical-acoustical transducers located in an equally-spaced circular array simultaneously generate a specified spinning mode and the cancelling mode. Analysis of the wave equation for the synthesizer established the optimum cancelling array acoustic parameters for maximum sound pressure level reduction. The parameter dependence of the frequency ranges of propagation of single, specified circumferential modes generated by a single array, and of effective cancellation of the modes generated by two arrays, was determined. Substantial sound pressure level reduction was obtained for modes within these limits.

Fiber glass pulling. [in space

NASA Technical Reports Server (NTRS)

Workman, Gary L.

1987-01-01

Experiments were conducted to determine the viability of performing containerless glass fiber pulling in space. The optical transmission properties and glass-forming capabilities of the heavy metal fluorides are reviewed and the acoustic characteristics required for a molten glass levitation system are examined. The design limitations of, and necessary modifications to the acoustic levitation furnace used in the experiments are discussed in detail. Acoustic levitator force measurements were performed and a thermal map of the furnace was generated from thermocouple data. It was determined that the thermal capability of the furnace was inadequate to melt a glass sample in the center. The substitution of a 10 KW carbon monoxide laser for the original furnace heating elements resulted in improved melt heating.

Modeling the effects of wind tunnel wall absorption on the acoustic radiation characteristics of propellers

NASA Technical Reports Server (NTRS)

Baumeister, K. J.; Eversman, W.

1986-01-01

Finite element theory is used to calculate the acoustic field of a propeller in a soft walled circular wind tunnel and to compare the radiation patterns to the same propeller in free space. Parametric solutions are present for a 'Gutin' propeller for a variety of flow Mach numbers, admittance values at the wall, microphone position locations, and propeller to duct radius ratios. Wind tunnel boundary layer is not included in this analysis. For wall admittance nearly equal to the characteristic value of free space, the free field and ducted propeller models agree in pressure level and directionality. In addition, the need for experimentally mapping the acoustic field is discussed.

Modeling the effects of wind tunnel wall absorption on the acoustic radiation characteristics of propellers

NASA Technical Reports Server (NTRS)

Baumeister, K. J.; Eversman, W.

1986-01-01

Finite element theory is used to calculate the acoustic field of a propeller in a soft walled circular wind tunnel and to compare the radiation patterns to the same propeller in free space. Parametric solutions are present for a "Gutin" propeller for a variety of flow Mach numbers, admittance values at the wall, microphone position locations, and propeller to duct radius ratios. Wind tunnel boundary layer is not included in this analysis. For wall admittance nearly equal to the characteristic value of free space, the free field and ducted propeller models agree in pressure level and directionality. In addition, the need for experimentally mapping the acoustic field is discussed.

Acoustic firearm discharge detection and classification in an enclosed environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luzi, Lorenzo; Gonzalez, Eric; Bruillard, Paul

2016-05-01

Two different signal processing algorithms are described for detection and classification of acoustic signals generated by firearm discharges in small enclosed spaces. The first is based on the logarithm of the signal energy. The second is a joint entropy. The current study indicates that a system using both signal energy and joint entropy would be able to both detect weapon discharges and classify weapon type, in small spaces, with high statistical certainty.

Robotics development for the enhancement of space endeavors

NASA Astrophysics Data System (ADS)

Mauceri, A. J.; Clarke, Margaret M.

Telerobotics and robotics development activities to support NASA's goal of increasing opportunities in space commercialization and exploration are described. The Rockwell International activities center is using robotics to improve efficiency and safety in three related areas: remote control of autonomous systems, automated nondestructive evaluation of aspects of vehicle integrity, and the use of robotics in space vehicle ground reprocessing operations. In the first area, autonomous robotic control, Rockwell is using the control architecture, NASREM, as the foundation for the high level command of robotic tasks. In the second area, we have demonstrated the use of nondestructive evaluation (using acoustic excitation and lasers sensors) to evaluate the integrity of space vehicle surface material bonds, using Orbiter 102 as the test case. In the third area, Rockwell is building an automated version of the present manual tool used for Space Shuttle surface tile re-waterproofing. The tool will be integrated into an orbiter processing robot being developed by a KSC-led team.

Acoustic Emission Weld Monitoring in the 2195 Aluminum-Lithium Alloy

NASA Technical Reports Server (NTRS)

Walker, James L.

2005-01-01

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

Effect of temporary open-air markets on the sound environment and acoustic perception based on the crowd density characteristics.

PubMed

Meng, Qi; Sun, Yang; Kang, Jian

2017-12-01

The sound environment and acoustic perception of open-air markets, which are very common in high-density urban open spaces, play important roles in terms of the urban soundscape. Based on objective and subjective measurements of a typical temporary open-air market in Harbin city, China, the effects of the temporary open-air market on the sound environment and acoustic perception were studied, considering different crowd densities. It was observed that a temporary open-air market without zoning increases the sound pressure level and subjective loudness by 2.4dBA and 0.21dBA, respectively, compared to the absence of a temporary market. Different from the sound pressure level and subjective loudness, the relationship between crowd density and the perceived acoustic comfort is parabolic. Regarding the effect of a temporary open-air market with different zones on the sound environment and acoustic perception, when the crowd densities were the same, subjective loudness in the fruit and vegetable sales area was always higher than in the food sales area and the clothing sales area. In terms of acoustic comfort, with an increase in crowd density, acoustic comfort in the fruit and vegetable sales area decreased, and acoustic comfort in the food sales area and the clothing sales area exhibited a parabolic change trend of increase followed by decrease. Overall, acoustic comfort can be effectively improved by better planning temporary open-air markets in high-density urban open spaces. Copyright © 2017 Elsevier B.V. All rights reserved.

The validation and application of a rotor acoustic prediction computer program

NASA Technical Reports Server (NTRS)

Gallman, Judith M.

1990-01-01

An essential prerequisite to reducing the acoustic detectability of military rotorcraft is a better understanding of main rotor noise which is the major contributor to the overall noise. A simple, yet accurate, Rotor Acoustic Prediction Program (RAPP) was developed to advance the understanding of main rotor noise. This prediction program uses the Ffowcs Williams and Hawkings (FW-H) equation. The particular form of the FW-H equation used is well suited for the coupling of the measured blade surface pressure to the prediction of acoustic pressure. The FW-H equation is an inhomogeneous wave equation that is valid in all space and governs acoustic pressure generated by thin moving bodies. The nonhomogeneous terms describe mass displacement due to surface motion and forces due to local surface stresses, such as viscous stress and pressure distribution on the surface. This paper examines two of the four types of main rotor noise: BVI noise and low-frequency noise. Blade-vortex interaction noise occurs when a tip vortex, previously shed by a rotor blade, passes close enough to a rotor blade to cause large variations in the blade surface pressures. This event is most disturbing when it happens on the advancing side of the rotor disk. Low-frequency noise includes hover and low to moderate speed forward flight. For these flight conditions, the low frequency components of the acoustic signal dominate.

Ultrasonic acoustic levitation for fast frame rate X-ray protein crystallography at room temperature.

PubMed

Tsujino, Soichiro; Tomizaki, Takashi

2016-05-06

Increasing the data acquisition rate of X-ray diffraction images for macromolecular crystals at room temperature at synchrotrons has the potential to significantly accelerate both structural analysis of biomolecules and structure-based drug developments. Using lysozyme model crystals, we demonstrated the rapid acquisition of X-ray diffraction datasets by combining a high frame rate pixel array detector with ultrasonic acoustic levitation of protein crystals in liquid droplets. The rapid spinning of the crystal within a levitating droplet ensured an efficient sampling of the reciprocal space. The datasets were processed with a program suite developed for serial femtosecond crystallography (SFX). The structure, which was solved by molecular replacement, was found to be identical to the structure obtained by the conventional oscillation method for up to a 1.8-Å resolution limit. In particular, the absence of protein crystal damage resulting from the acoustic levitation was carefully established. These results represent a key step towards a fully automated sample handling and measurement pipeline, which has promising prospects for a high acquisition rate and high sample efficiency for room temperature X-ray crystallography.

Ultrasonic acoustic levitation for fast frame rate X-ray protein crystallography at room temperature

NASA Astrophysics Data System (ADS)

Tsujino, Soichiro; Tomizaki, Takashi

2016-05-01

Increasing the data acquisition rate of X-ray diffraction images for macromolecular crystals at room temperature at synchrotrons has the potential to significantly accelerate both structural analysis of biomolecules and structure-based drug developments. Using lysozyme model crystals, we demonstrated the rapid acquisition of X-ray diffraction datasets by combining a high frame rate pixel array detector with ultrasonic acoustic levitation of protein crystals in liquid droplets. The rapid spinning of the crystal within a levitating droplet ensured an efficient sampling of the reciprocal space. The datasets were processed with a program suite developed for serial femtosecond crystallography (SFX). The structure, which was solved by molecular replacement, was found to be identical to the structure obtained by the conventional oscillation method for up to a 1.8-Å resolution limit. In particular, the absence of protein crystal damage resulting from the acoustic levitation was carefully established. These results represent a key step towards a fully automated sample handling and measurement pipeline, which has promising prospects for a high acquisition rate and high sample efficiency for room temperature X-ray crystallography.

Ultrasonic acoustic levitation for fast frame rate X-ray protein crystallography at room temperature

PubMed Central

Tsujino, Soichiro; Tomizaki, Takashi

2016-01-01

Increasing the data acquisition rate of X-ray diffraction images for macromolecular crystals at room temperature at synchrotrons has the potential to significantly accelerate both structural analysis of biomolecules and structure-based drug developments. Using lysozyme model crystals, we demonstrated the rapid acquisition of X-ray diffraction datasets by combining a high frame rate pixel array detector with ultrasonic acoustic levitation of protein crystals in liquid droplets. The rapid spinning of the crystal within a levitating droplet ensured an efficient sampling of the reciprocal space. The datasets were processed with a program suite developed for serial femtosecond crystallography (SFX). The structure, which was solved by molecular replacement, was found to be identical to the structure obtained by the conventional oscillation method for up to a 1.8-Å resolution limit. In particular, the absence of protein crystal damage resulting from the acoustic levitation was carefully established. These results represent a key step towards a fully automated sample handling and measurement pipeline, which has promising prospects for a high acquisition rate and high sample efficiency for room temperature X-ray crystallography. PMID:27150272

Tomographic reconstruction of atmospheric turbulence with the use of time-dependent stochastic inversion.

PubMed

Vecherin, Sergey N; Ostashev, Vladimir E; Ziemann, A; Wilson, D Keith; Arnold, K; Barth, M

2007-09-01

Acoustic travel-time tomography allows one to reconstruct temperature and wind velocity fields in the atmosphere. In a recently published paper [S. Vecherin et al., J. Acoust. Soc. Am. 119, 2579 (2006)], a time-dependent stochastic inversion (TDSI) was developed for the reconstruction of these fields from travel times of sound propagation between sources and receivers in a tomography array. TDSI accounts for the correlation of temperature and wind velocity fluctuations both in space and time and therefore yields more accurate reconstruction of these fields in comparison with algebraic techniques and regular stochastic inversion. To use TDSI, one needs to estimate spatial-temporal covariance functions of temperature and wind velocity fluctuations. In this paper, these spatial-temporal covariance functions are derived for locally frozen turbulence which is a more general concept than a widely used hypothesis of frozen turbulence. The developed theory is applied to reconstruction of temperature and wind velocity fields in the acoustic tomography experiment carried out by University of Leipzig, Germany. The reconstructed temperature and velocity fields are presented and errors in reconstruction of these fields are studied.

Containerless processing of glass forming melts in space

NASA Technical Reports Server (NTRS)

Day, D. E.; Ray, C. S.

1988-01-01

The near weightlessness of a material in the reduced gravity environment of space offers the opportunity of melting and cooling glass forming compositions without a container. This reduces the heterogeneous nucleation/crystallization which usually occurs at the walls of the container, thereby, extending the range of glass forming compositions. Based primarily on this idea, containerless glass forming experiments, which used a single axis acoustic levitator/furnace (SAAL), were conducted on SPAR rocket flights, 6 and 8, and on Space Shuttle mission, STS-7 and STS-61A. The experiments on the Space Shuttle were designed to include other studies related to melt homogenization and mixing, development of techniques for preparing uncontaminated preflight samples, and simple shaping experiments.

The design of L1-norm visco-acoustic wavefield extrapolators

NASA Astrophysics Data System (ADS)

Salam, Syed Abdul; Mousa, Wail A.

2018-04-01

Explicit depth frequency-space (f - x) prestack imaging is an attractive mechanism for seismic imaging. To date, the main focus of this method was data migration assuming an acoustic medium, but until now very little work assumed visco-acoustic media. Real seismic data usually suffer from attenuation and dispersion effects. To compensate for attenuation in a visco-acoustic medium, new operators are required. We propose using the L1-norm minimization technique to design visco-acoustic f - x extrapolators. To show the accuracy and compensation of the operators, prestack depth migration is performed on the challenging Marmousi model for both acoustic and visco-acoustic datasets. The final migrated images show that the proposed L1-norm extrapolation results in practically stable and improved resolution of the images.

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 interferometric techniques have good potential for improving the lightning location accuracy and detection efficiency of acoustic arrays.

Analysis of Noise Exposure Measurements Made Onboard the International Space Station

NASA Technical Reports Server (NTRS)

Limardo, Jose G.; Allen, Christopher S.

2011-01-01

The International Space Station (ISS) is a unique workplace environment for U.S. astronauts and Russian cosmonauts to conduct research and live for a period of six months or more. Noise has been an enduring environmental physical hazard that has been a challenge for the U.S. space program since before the Apollo era. Noise exposure in ISS poses significant risks to the crewmembers, such as; hearing loss (temporary or permanent), possible disruptions of crew sleep, interference with speech intelligibility and communication, possible interference with crew task performance, and possible reduction in alarm audibility. Acoustic measurements are made aboard ISS and compared to requirements in order to assess the acoustic environment to which the crewmembers are exposed. The purpose of this paper is to describe in detail the noise exposure monitoring program as well as an assessment of the acoustic dosimeter data collected to date. The hardware currently being used for monitoring the noise exposure onboard ISS will be discussed. Acoustic data onboard ISS has been collected since the beginning of ISS (Increment 1, November 2000). Noise exposure data analysis will include acoustic dosimetry logged data from crew-worn during work and sleep periods and also fixed-location measurements from Increment 1 to present day. Noise exposure levels (8-, 16- and 24-hr), LEQ, will also be provided and discussed in this paper. Discussions related to hearing protection will also be included. Future directions and recommendations for the noise exposure monitoring program will be highlighted. This acoustic data is used to ensure a safe and healthy working and living environment for the crewmembers aboard the ISS.

Analysis of Noise Exposure Measurements Acquired Onboard the International Space Station

NASA Technical Reports Server (NTRS)

Limardo, Jose G.; Allen, Christopher S.

2011-01-01

The International Space Station (ISS) is a unique workplace environment for U.S. astronauts and Russian cosmonauts to conduct research and live for a period of six months or more. Noise has been an enduring environmental physical hazard that has been a challenge for the U.S. space program since before the Apollo era. Noise exposure in ISS poses significant risks to the crewmembers, such as; hearing loss (temporary or permanent), possible disruptions of crew sleep, interference with speech intelligibility and communication, possible interference with crew task performance, and possible reduction in alarm audibility. Acoustic measurements were made onboard ISS and compared to requirements in order to assess the acoustic environment to which the crewmembers are exposed. The purpose of this paper is to describe in detail the noise exposure monitoring program as well as an assessment of the acoustic dosimeter data collected to date. The hardware currently being used for monitoring the noise exposure onboard ISS will be discussed. Acoustic data onboard ISS has been collected since the beginning of ISS (Increment 1, November 2001). Noise exposure data analysis will include acoustic dosimetry logged data from crew-worn dosimeters during work and sleep periods and also fixed-location measurements from Increment 1 to present day. Noise exposure levels (8-, 16- and 24-hr), LEQ, will also be provided and discussed in this paper. Future directions and recommendations for the noise exposure monitoring program will be highlighted. This acoustic data is used to ensure a safe and healthy working and living environment for the crewmembers onboard the ISS.

Multi-domain boundary element method for axi-symmetric layered linear acoustic systems

NASA Astrophysics Data System (ADS)

Reiter, Paul; Ziegelwanger, Harald

2017-12-01

Homogeneous porous materials like rock wool or synthetic foam are the main tool for acoustic absorption. The conventional absorbing structure for sound-proofing consists of one or multiple absorbers placed in front of a rigid wall, with or without air-gaps in between. Various models exist to describe these so called multi-layered acoustic systems mathematically for incoming plane waves. However, there is no efficient method to calculate the sound field in a half space above a multi layered acoustic system for an incoming spherical wave. In this work, an axi-symmetric multi-domain boundary element method (BEM) for absorbing multi layered acoustic systems and incoming spherical waves is introduced. In the proposed BEM formulation, a complex wave number is used to model absorbing materials as a fluid and a coordinate transformation is introduced which simplifies singular integrals of the conventional BEM to non-singular radial and angular integrals. The radial and angular part are integrated analytically and numerically, respectively. The output of the method can be interpreted as a numerical half space Green's function for grounds consisting of layered materials.

Liquid Rocket Booster (LRB) for the Space Transportation System (STS) systems study. Appendix B: Liquid rocket booster acoustic and thermal environments

NASA Technical Reports Server (NTRS)

1989-01-01

The ascent thermal environment and propulsion acoustic sources for the Martin-Marietta Corporation designed Liquid Rocket Boosters (LRB) to be used with the Space Shuttle Orbiter and External Tank are described. Two designs were proposed: one using a pump-fed propulsion system and the other using a pressure-fed propulsion system. Both designs use LOX/RP-1 propellants, but differences in performance of the two propulsion systems produce significant differences in the proposed stage geometries, exhaust plumes, and resulting environments. The general characteristics of the two designs which are significant for environmental predictions are described. The methods of analysis and predictions for environments in acoustics, aerodynamic heating, and base heating (from exhaust plume effects) are also described. The acoustic section will compare the proposed exhaust plumes with the current SRB from the standpoint of acoustics and ignition overpressure. The sections on thermal environments will provide details of the LRB heating rates and indications of possible changes in the Orbiter and ET environments as a result of the change from SRBs to LRBs.

An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Article's Absorption During Reverberant Chamber Acoustic Testing of Spaceflight Hardware

NASA Technical Reports Server (NTRS)

Hozman, Aron D.; Hughes, William O.

2014-01-01

The exposure of a customer's aerospace test-article to a simulated acoustic launch environment is typically performed in a reverberant acoustic test chamber. The acoustic pre-test runs that will ensure that the sound pressure levels of this environment can indeed be met by a test facility are normally performed without a test-article dynamic simulator of representative acoustic absorption and size. If an acoustic test facility's available acoustic power capability becomes maximized with the test-article installed during the actual test then the customer's environment requirement may become compromised. In order to understand the risk of not achieving the customer's in-tolerance spectrum requirement with the test-article installed, an acoustic power margin evaluation as a function of frequency may be performed by the test facility. The method for this evaluation of acoustic power will be discussed in this paper. This method was recently applied at the NASA Glenn Research Center Plum Brook Station's Reverberant Acoustic Test Facility for the SpaceX Falcon 9 Payload Fairing acoustic test program.

An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Article's Absorption during Reverberant Chamber Acoustic Testing of Spaceflight Hardware

NASA Technical Reports Server (NTRS)

Hozman, Aron D.; Hughes, William O.

2014-01-01

The exposure of a customers aerospace test-article to a simulated acoustic launch environment is typically performed in a reverberant acoustic test chamber. The acoustic pre-test runs that will ensure that the sound pressure levels of this environment can indeed be met by a test facility are normally performed without a test-article dynamic simulator of representative acoustic absorption and size. If an acoustic test facilitys available acoustic power capability becomes maximized with the test-article installed during the actual test then the customers environment requirement may become compromised. In order to understand the risk of not achieving the customers in-tolerance spectrum requirement with the test-article installed, an acoustic power margin evaluation as a function of frequency may be performed by the test facility. The method for this evaluation of acoustic power will be discussed in this paper. This method was recently applied at the NASA Glenn Research Center Plum Brook Stations Reverberant Acoustic Test Facility for the SpaceX Falcon 9 Payload Fairing acoustic test program.

Vowel change across three age groups of speakers in three regional varieties of American English

PubMed Central

Jacewicz, Ewa; Fox, Robert A.; Salmons, Joseph

2011-01-01

This acoustic study examines sound (vowel) change in apparent time across three successive generations of 123 adult female speakers ranging in age from 20 to 65 years old, representing three regional varieties of American English, typical of western North Carolina, central Ohio and southeastern Wisconsin. A set of acoustic measures characterized the dynamic nature of formant trajectories, the amount of spectral change over the course of vowel duration and the position of the spectral centroid. The study found a set of systematic changes to /I, ε, æ/ including positional changes in the acoustic space (mostly lowering of the vowels) and significant variation in formant dynamics (increased monophthongization). This common sound change is evident in both emphatic (articulated clearly) and nonemphatic (casual) productions and occurs regardless of dialect-specific vowel dispersions in the vowel space. The cross-generational and cross-dialectal patterns of variation found here support an earlier report by Jacewicz, Fox, and Salmons (2011) which found this recent development in these three dialect regions in isolated citation-form words. While confirming the new North American Shift in different styles of production, the study underscores the importance of addressing the stress-related variation in vowel production in a careful and valid assessment of sound change. PMID:22125350

Mortar and artillery variants classification by exploiting characteristics of the acoustic signature

NASA Astrophysics Data System (ADS)

Hohil, Myron E.; Grasing, David; Desai, Sachi; Morcos, Amir

2007-10-01

Feature extraction methods based on the discrete wavelet transform and multiresolution analysis facilitate the development of a robust classification algorithm that reliably discriminates mortar and artillery variants via acoustic signals produced during the launch/impact events. Utilizing acoustic sensors to exploit the sound waveform generated from the blast for the identification of mortar and artillery variants. Distinct characteristics arise within the different mortar variants because varying HE mortar payloads and related charges emphasize concussive and shrapnel effects upon impact employing varying magnitude explosions. The different mortar variants are characterized by variations in the resulting waveform of the event. The waveform holds various harmonic properties distinct to a given mortar/artillery variant that through advanced signal processing techniques can employed to classify a given set. The DWT and other readily available signal processing techniques will be used to extract the predominant components of these characteristics from the acoustic signatures at ranges exceeding 2km. Exploiting these techniques will help develop a feature set highly independent of range, providing discrimination based on acoustic elements of the blast wave. Highly reliable discrimination will be achieved with a feed-forward neural network classifier trained on a feature space derived from the distribution of wavelet coefficients, frequency spectrum, and higher frequency details found within different levels of the multiresolution decomposition. The process that will be described herein extends current technologies, which emphasis multi modal sensor fusion suites to provide such situational awareness. A two fold problem of energy consumption and line of sight arise with the multi modal sensor suites. The process described within will exploit the acoustic properties of the event to provide variant classification as added situational awareness to the solider.

Development of the Space Debris Sensor

NASA Technical Reports Server (NTRS)

Hamilton, J.; Liou, J.-C.; Anz-Meador, P. D.; Corsaro, B.; Giovane, F.; Matney, M.; Christiansen, E.

2017-01-01

The Space Debris Sensor (SDS) is a NASA experiment scheduled to fly aboard the International Space Station (ISS) starting in 2017. The SDS is the first flight demonstration of the Debris Resistive/Acoustic Grid Orbital NASA-Navy Sensor (DRAGONS) developed and matured by the NASA Orbital Debris Program Office. The DRAGONS concept combines several technologies to characterize the size, speed, direction, and density of small impacting objects. With a minimum two-year operational lifetime, SDS is anticipated to collect statistically significant information on orbital debris ranging from 50 micron to 500 micron in size. This paper describes the SDS features and how data from the ISS mission may be used to update debris environment models. Results of hypervelocity impact testing during the development of SDS and the potential for improvement on future sensors at higher altitudes will be reviewed.

Acoustic Emission Detection of Impact Damage on Space Shuttle Structures

NASA Technical Reports Server (NTRS)

Prosser, William H.; Gorman, Michael R.; Madaras, Eric I.

2004-01-01

The loss of the Space Shuttle Columbia as a result of impact damage from foam debris during ascent has led NASA to investigate the feasibility of on-board impact detection technologies. AE sensing has been utilized to monitor a wide variety of impact conditions on Space Shuttle components ranging from insulating foam and ablator materials, and ice at ascent velocities to simulated hypervelocity micrometeoroid and orbital debris impacts. Impact testing has been performed on both reinforced carbon composite leading edge materials as well as Shuttle tile materials on representative aluminum wing structures. Results of these impact tests will be presented with a focus on the acoustic emission sensor responses to these impact conditions. These tests have demonstrated the potential of employing an on-board Shuttle impact detection system. We will describe the present plans for implementation of an initial, very low frequency acoustic impact sensing system using pre-existing flight qualified hardware. The details of an accompanying flight measurement system to assess the Shuttle s acoustic background noise environment as a function of frequency will be described. The background noise assessment is being performed to optimize the frequency range of sensing for a planned future upgrade to the initial impact sensing system.

Observation of self-excited acoustic vortices in defect-mediated dust acoustic wave turbulence.

PubMed

Tsai, Ya-Yi; I, Lin

2014-07-01

Using the self-excited dust acoustic wave as a platform, we demonstrate experimental observation of self-excited fluctuating acoustic vortex pairs with ± 1 topological charges through spontaneous waveform undulation in defect-mediated turbulence for three-dimensional traveling nonlinear longitudinal waves. The acoustic vortex pair has helical waveforms with opposite chirality around the low-density hole filament pair in xyt space (the xy plane is the plane normal to the wave propagation direction). It is generated through ruptures of sequential crest surfaces and reconnections with their trailing ruptured crest surfaces. The initial rupture is originated from the amplitude reduction induced by the formation of the kinked wave crest strip with strong stretching through the undulation instability. Increasing rupture causes the separation of the acoustic vortex pair after generation. A similar reverse process is followed for the acoustic vortex annihilating with the opposite-charged acoustic vortex from the same or another pair generation.

3-D Sound for Virtual Reality and Multimedia

NASA Technical Reports Server (NTRS)

Begault, Durand R.; Trejo, Leonard J. (Technical Monitor)

2000-01-01

Technology and applications for the rendering of virtual acoustic spaces are reviewed. Chapter 1 deals with acoustics and psychoacoustics. Chapters 2 and 3 cover cues to spatial hearing and review psychoacoustic literature. Chapter 4 covers signal processing and systems overviews of 3-D sound systems. Chapter 5 covers applications to computer workstations, communication systems, aeronautics and space, and sonic arts. Chapter 6 lists resources. This TM is a reprint of the 1994 book from Academic Press.

Digital servo control of random sound test excitation. [in reverberant acoustic chamber

NASA Technical Reports Server (NTRS)

Nakich, R. B. (Inventor)

1974-01-01

A digital servocontrol system for random noise excitation of a test object in a reverberant acoustic chamber employs a plurality of sensors spaced in the sound field to produce signals in separate channels which are decorrelated and averaged. The average signal is divided into a plurality of adjacent frequency bands cyclically sampled by a time division multiplex system, converted into digital form, and compared to a predetermined spectrum value stored in digital form. The results of the comparisons are used to control a time-shared up-down counter to develop gain control signals for the respective frequency bands in the spectrum of random sound energy picked up by the microphones.

NASA Rat Acoustic Tolerance Test 1994-1995

NASA Technical Reports Server (NTRS)

Holley, Daniel C.; Mele, Gary D.; Naidu, Sujata

1996-01-01

The major objective of this Cooperative Agreement was to develop a noise level specification for laboratory rats in the Centrifuge Facility Specimen Chambers (Space Station Biological Research Project), and to validate the specification for 3 noise octave bands: center frequencies 8 kHz, 16, kHz, and 32 kHz. This has been accomplished. Objective measures were used to verify that the chronic noise exposure was not harmful to the animals from physiological and behavioral perspectives. These measures were defined in the Stress Assessment Battery Validation for the Rat Acoustic Tolerance Test. In addition, the effects of the chronic noise exposure on rat hearing was assessed by the Brainstem Auditory Evoked Potential Method (BAER).

Modal content of noise generated by a coaxial jet in a pipe

NASA Technical Reports Server (NTRS)

Kerschen, E. J.; Johnston, J. P.

1978-01-01

Noise generated by air flow through a coaxial obstruction in a long, straight pipe was investigated with concentration on the modal characteristics of the noise field inside the pipe and downstream of the restriction. Two measurement techniques were developed for separation of the noise into the acoustic duct modes. The instantaneous mode separation technique uses four microphones, equally spaced in the circumferential direction, at the same axial location. The time-averaged mode separation technique uses three microphones mounted at the same axial location. A matrix operation on time-averaged data produces the modal pressure levels. This technique requires the restrictive assumption that the acoustic modes are uncorrelated with each other. The measured modal pressure spectra were converted to modal power spectra and integrated over the frequency range 200-6000 Hz. The acoustic efficiency levels (acoustic power normalized by jet kinetic energy flow), when plotted vs. jet Mach number, showed a strong dependence on the ratio of restriction diameter to pipe diameter. The acoustic energy flow analyses based on the thermodynamic energy equation and on the results of Mohring both resulted in orthogonality properties for the eigenfunctions of the radial mode shape equation. These orthogonality relationships involve the eigenvalues and derivatives of the radial mode shape functions.

Infrasound from ground to space

NASA Astrophysics Data System (ADS)

Bowman, Daniel Charles

Acoustic detector networks are usually located on the Earth's surface. However, these networks suffer from shortcomings such as poor detection range and pervasive wind noise. An alternative is to deploy acoustic sensors on high altitude balloons. In theory, such platforms can resolve signals arriving from great distances, acquire others that never reach the surface at all, and avoid wind noise entirely. This dissertation focuses on scientific advances, instrumentation, and analytical techniques resulting from the development of such sensor arrays. Results from infrasound microphones deployed on balloon flights in the middle stratosphere are described, and acoustic sources such as the ocean microbarom and building ventilation systems are discussed. Electromagnetic noise originating from the balloon, flight system, and other payloads is shown to be a pervasive issue. An experiment investigating acoustic sensor calibration at low pressures is presented, and implications for high altitude recording are considered. Outstanding challenges and opportunities in sound measurement using sensors embedded in the free atmosphere are outlined. Acoustic signals from field scale explosions designed to emulate volcanic eruptions are described, and their generation mechanisms modeled. Wave forms recorded on sensors suspended from tethered helium balloons are compared with those detected on ground stations during the experiment. Finally, the Hilbert-Huang transform, a high time resolution spectral analysis method for nonstationary and nonlinear time series, is presented.

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.

Mesh-type acoustic vector sensor

NASA Astrophysics Data System (ADS)

Zalalutdinov, M. K.; Photiadis, D. M.; Szymczak, W. G.; McMahon, J. W.; Bucaro, J. A.; Houston, B. H.

2017-07-01

Motivated by the predictions of a theoretical model developed to describe the acoustic flow force exerted on closely spaced nano-fibers in a viscous medium, we have demonstrated a novel concept for a particle velocity-based directional acoustic sensor. The central element of the concept exploits the acoustically induced normal displacement of a fine mesh as a measure of the collinear projection of the particle velocity in the sound wave. The key observations are (i) the acoustically induced flow force on an individual fiber within the mesh is nearly independent of the fiber diameter and (ii) the mesh-flow interaction can be well-described theoretically by a nearest neighbor coupling approximation. Scaling arguments based on these two observations indicate that the refinement of the mesh down to the nanoscale leads to significant improvements in performance. The combination of the two dimensional nature of the mesh together with the nanoscale dimensions provides a dramatic gain in the total length of fiber exposed to the flow, leading to a sensitivity enhancement by orders of magnitude. We describe the fabrication of a prototype mesh sensor equipped with optical readout. Preliminary measurements carried out over a considerable bandwidth together with the results of numerical simulations are in good agreement with the theory, thus providing a proof of concept.

Acoustical heat pumping engine

DOEpatents

Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

1983-08-16

The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium.

Acoustical heat pumping engine

DOEpatents

Wheatley, J.C.; Swift, G.W.; Migliori, A.

1983-08-16

The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium. 2 figs.

Lateral attenuation of aircraft sound levels over an acoustically hard water surface : Logan Airport study

DOT National Transportation Integrated Search

2000-05-01

The National Aeronautics and Space Administration (NASA), Langley Research Center (LaRC), sponsored the Acoustics Facility at the United States Department of Transportation's John A. Volpe National Transportation Systems Center (Volpe Center) and the...

Vibrations and structureborne noise in space station

NASA Technical Reports Server (NTRS)

Vaicaitis, R.

1985-01-01

Theoretical models were developed capable of predicting structural response and noise transmission to random point mechanical loads. Fiber reinforced composite and aluminum materials were considered. Cylindrical shells and circular plates were taken as typical representatives of structural components for space station habitability modules. Analytical formulations include double wall and single wall constructions. Pressurized and unpressurized models were considered. Parametric studies were conducted to determine the effect on structural response and noise transmission due to fiber orientation, point load location, damping in the core and the main load carrying structure, pressurization, interior acoustic absorption, etc. These analytical models could serve as preliminary tools for assessing noise related problems, for space station applications.

Multi-Source Fusion for Explosive Hazard Detection in Forward Looking Sensors

DTIC Science & Technology

2016-12-01

include; (1) Investigating (a) thermal, (b) synthetic aperture acoustics ( SAA ) and (c) voxel space Radar for buried and side threat attacks. (2...detection. (3) With respect to SAA , we developed new approaches in the time and frequency domains for analyzing signature of concealed targets (called...Fraz). We also developed a method to extract a multi-spectral signature from SAA and deep learning was used on limited training and class imbalance

Underexpanded Screeching Jets From Circular, Rectangular, and Elliptic Nozzles

NASA Technical Reports Server (NTRS)

Panda, J.; Raman, G.; Zaman, K. B. M. Q.

2004-01-01

The screech frequency and amplitude, the shock spacing, the hydrodynamic-acoustic standing wave spacing, and the convective velocity of large organized structures are measured in the nominal Mach number range of 1.1 less than or = Mj less that or = l0.9 for supersonic, underexpanded jets exhausting from a circular, a rectangular and an elliptic nozzle. This provides a carefully measured data set useful in comparing the importance of various physical parameters in the screech generation process. The hydrodynamic-acoustic standing wave is formed between the potential pressure field of large turbulent structures and the acoustic pressure field of the screech sound. It has been demonstrated earlier that in the currently available screech frequency prediction models replacement of the shock spacing by the standing wave spacing provides an exact expression. In view of this newly found evidence, a comparison is made between the average standing wavelength and the average shock spacing. It is found that there exists a small, yet important, difference, which is dependent on the azimuthal screech mode. For example, in the flapping modes of circular, rectangular, and elliptic jets, the standing wavelength is slightly longer than the shock spacing, while for the helical screech mode in a circular jet the opposite is true. This difference accounts for the departure of the existing models from predicting the exact screech frequency. Another important parameter, necessary in screech prediction, is the convective velocity of the large organized structures. It is demonstrated that the presence of the hydrodynamic-acoustic standing wave, even inside the jet shear layer, becomes a significant source of error in the convective velocity data obtained using the conventional methods. However, a new relationship, using the standing wavelength and screech frequency is shown to provide more accurate results.

Recent Stirling Conversion Technology Developments and Operational Measurements at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Oriti, Salvatore M.; Schifer, Nicholas A.

2010-01-01

In support of the Advanced Stirling Radioisotope Generator (ASRG) project and other potential applications, NASA Glenn Research Center (GRC) has initiated convertor technology development efforts in the areas of acoustic emission, electromagnetic field mitigation, thermoacoustic Stirling conversion, and multiple-cylinder alpha arrangements of Stirling machines. The acoustic emission measurement effort was developed as a health monitoring metric for several Stirling convertors undergoing life testing. While accelerometers have been used in the past to monitor dynamic signature, the acoustic sensors were chosen to monitor cycle events, such gas bearing operation. Several electromagnetic interference (EMI) experiments were performed on a pair of Advanced Stirling Convertors (ASC). These tests demonstrated that a simple bucking coil was capable of reducing the alternating current (ac) magnetic field below the ASRG system specification. The thermoacoustic Stirling concept eliminates the displacer typically found in Stirling machines by making use of the pressure oscillations of a traveling acoustic wave. A 100 W-class thermoacoustic Stirling prototype manufactured by Northrop Grumman Space and Technology was received and tested. Another thermoacoustic prototype designed and fabricated by Sunpower, Inc., will be tested in the near future. A four cylinder free piston alpha prototype convertor was received from Sunpower, Inc. and has been tested at GRC. This hardware was used as a proof of concept to validate thermodynamic models and demonstrate stable operation of multiple-cylinder free-piston Stirling conversion. This paper will discuss each of these activities and the results they produced.

Graphical Acoustic Liner Design and Analysis Tool

NASA Technical Reports Server (NTRS)

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

2016-01-01

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

A study to define an in-flight dynamics measurement and data applications program for space shuttle payloads

NASA Technical Reports Server (NTRS)

Rader, W. P.; Barrett, S.; Payne, K. R.

1975-01-01

Data measurement and interpretation techniques were defined for application to the first few space shuttle flights, so that the dynamic environment could be sufficiently well established to be used to reduce the cost of future payloads through more efficient design and environmental test techniques. It was concluded that: (1) initial payloads must be given comprehensive instrumentation coverage to obtain detailed definition of acoustics, vibration, and interface loads, (2) analytical models of selected initial payloads must be developed and verified by modal surveys and flight measurements, (3) acoustic tests should be performed on initial payloads to establish realistic test criteria for components and experiments in order to minimize unrealistic failures and retest requirements, (4) permanent data banks should be set up to establish statistical confidence in the data to be used, (5) a more unified design/test specification philosophy is needed, (6) additional work is needed to establish a practical testing technique for simulation of vehicle transients.

Spectra analysis of nonuniform FBG-based acousto-optic modulator by using Fourier mode coupling theory.

PubMed

Liu, Chao; Pei, Li; Li, Zhuoxuan; Ning, Tigang; Yu, Shaowei; Kang, Zexin

2013-05-10

Fourier mode coupling theory was first employed in the spectral analysis of several nonuniform fiber Bragg grating (FBG)-based acousto-optic modulators (NU-FBG-AOMs) with the effects of Gaussian-apodization (GA), phase shift (PS), and linear chirp (LC). Because of the accuracy and simplicity of the algorithm applied in this model, the modulation performances of these modulators can be acquired effectively and efficiently. Based on the model, the reflected spectra of these modulators were simulated under various acoustic frequencies and acoustically induced strains. The simulation results of the GA-FBG-AOM and PS-FBG-AOM showed that the wavelength spacing between the primary reflection peak and the secondary reflection peak is proportional to the acoustic frequency, and the reflectivity of reflection peaks depends on the acoustically induced strains. But for the LC-FBG-AOM, the wavelength spacing between the neighboring reflection peaks increased linearly and inversely with the acoustic frequency, and the extinction ratio of each peak relates to the acoustically induced strain. These numerical analysis results, which were effectively used in the designs and fabrications of these NU-FBG-AOMs, can broaden the AOM-based application scope and shed light on the performance optimization of optical wavelength-division multiplex system.

Virtual Acoustics: Evaluation of Psychoacoustic Parameters

NASA Technical Reports Server (NTRS)

Begault, Durand R.; Null, Cynthia H. (Technical Monitor)

1997-01-01

Current virtual acoustic displays for teleconferencing and virtual reality are usually limited to very simple or non-existent renderings of reverberation, a fundamental part of the acoustic environmental context that is encountered in day-to-day hearing. Several research efforts have produced results that suggest that environmental cues dramatically improve perceptual performance within virtual acoustic displays, and that is possible to manipulate signal processing parameters to effectively reproduce important aspects of virtual acoustic perception in real-time. However, the computational resources for rendering reverberation remain formidable. Our efforts at NASA Ames have been focused using a several perceptual threshold metrics, to determine how various "trade-offs" might be made in real-time acoustic rendering. This includes both original work and confirmation of existing data that was obtained in real rather than virtual environments. The talk will consider the importance of using individualized versus generalized pinnae cues (the "Head-Related Transfer Function"); the use of head movement cues; threshold data for early reflections and late reverberation; and consideration of the necessary accuracy for measuring and rendering octave-band absorption characteristics of various wall surfaces. In addition, a consideration of the analysis-synthesis of the reverberation within "everyday spaces" (offices, conference rooms) will be contrasted to the commonly used paradigm of concert hall spaces.

Comments on ``intimacy'' and ITDG concepts in musical performing spaces

NASA Astrophysics Data System (ADS)

Beranek, Leo L.

2004-05-01

The word ``intimacy'' as related to the initial-time-delay gap (ITDG) measured in halls for musical performance was born in 1961. Of two concert spaces, one was successful acoustically and the other much less so. The halls had the same number of seats and reverberation times, the principal difference being their ITDG's. To many, the hall with larger ITDG sounded arena-like and thus not ``intimate.'' The effect of differing ITDGs appears in three of the author's books (Wiley, New York, 1962), (Acoustical Soc. of America, Melville, NY, 1996), and (Springer-Verlag, NY, 2003), with the conclusion that ITDG is an important parameter affecting the acoustical quality of concert halls and opera houses. The question is whether the word ``intimacy,'' used in an acoustical sense, should be synonymous with ITDG. Barron (Spon, London, 1993) defines, ``Intimacy refers to the degree of identification between the listener and the performance, whether the listener feels acoustically involved or detached from the music.'' He found from jury subjective judgments that there was little correlation between ITDG and the word ``intimacy.'' This paper presents the author's present thinking on the usefulness of the word ``intimacy'' in acoustics of halls for music, and discusses experiences with the visual effect on ``intimacy.''

Effect of diffusive and nondiffusive surfaces combinations on sound diffusion

NASA Astrophysics Data System (ADS)

Shafieian, Masoume; Kashani, Farokh Hodjat

2010-05-01

One of room acoustic goals, especially in small to medium rooms, is sound diffusion in low frequencies, which have been the subject of lots of researches. Sound diffusion is a very important consideration in acoustics because it minimizes the coherent reflections that cause problems. It also tends to make an enclosed space sound larger than it is. Diffusion is an excellent alternative or complement to sound absorption in acoustic treatment because it doesn’t really remove much energy, which means it can be used to effectively reduce reflections while still leaving an ambient or live sounding space. Distribution of diffusive and nondiffusive surfaces on room walls affect sound diffusion in room, but the amount, combination, and location of these surfaces are still the matter of question. This paper investigates effects of these issues on room acoustic frequency response in different parts of the room with different source-receiver locations. Room acoustic model based on wave method is used (implemented) which is very accurate and convenient for low frequencies in such rooms. Different distributions of acoustic surfaces on room walls have been introduced to the model and room frequency response results are calculated. For the purpose of comparison, some measurements results are presented. Finally for more smooth frequency response in small and medium rooms, some suggestions are made.

Methane gas hydrate effect on sediment acoustic and strength properties

USGS Publications Warehouse

Winters, W.J.; Waite, W.F.; Mason, D.H.; Gilbert, L.Y.; Pecher, I.A.

2007-01-01

To improve our understanding of the interaction of methane gas hydrate with host sediment, we studied: (1) the effects of gas hydrate and ice on acoustic velocity in different sediment types, (2) effect of different hydrate formation mechanisms on measured acoustic properties (3) dependence of shear strength on pore space contents, and (4) pore pressure effects during undrained shear.A wide range in acoustic p-wave velocities (Vp) were measured in coarse-grained sediment for different pore space occupants. Vp ranged from less than 1 km/s for gas-charged sediment to 1.77–1.94 km/s for water-saturated sediment, 2.91–4.00 km/s for sediment with varying degrees of hydrate saturation, and 3.88–4.33 km/s for frozen sediment. Vp measured in fine-grained sediment containing gas hydrate was substantially lower (1.97 km/s). Acoustic models based on measured Vp indicate that hydrate which formed in high gas flux environments can cement coarse-grained sediment, whereas hydrate formed from methane dissolved in the pore fluid may not.The presence of gas hydrate and other solid pore-filling material, such as ice, increased the sediment shear strength. The magnitude of that increase is related to the amount of hydrate in the pore space and cementation characteristics between the hydrate and sediment grains. We have found, that for consolidation stresses associated with the upper several hundred meters of sub-bottom depth, pore pressures decreased during shear in coarse-grained sediment containing gas hydrate, whereas pore pressure in fine-grained sediment typically increased during shear. The presence of free gas in pore spaces damped pore pressure response during shear and reduced the strengthening effect of gas hydrate in sands.

Two stage low noise advanced technology fan. 1: Aerodynamic, structural, and acoustic design

NASA Technical Reports Server (NTRS)

Messenger, H. E.; Ruschak, J. T.; Sofrin, T. G.

1974-01-01

A two-stage fan was designed to reduce noise 20 db below current requirements. The first-stage rotor has a design tip speed of 365.8 m/sec and a hub/tip ratio of 0.4. The fan was designed to deliver a pressure ratio of 1.9 with an adiabatic efficiency of 85.3 percent at a specific inlet corrected flow of 209.2kg/sec/sq m. Noise reduction devices include acoustically treated casing walls, a flowpath exit acoustic splitter, a translating centerbody sonic inlet device, widely spaced blade rows, and the proper ratio of blades and vanes. Multiple-circular-arc rotor airfoils, resettable stators, split outer casings, and capability to go to close blade-row spacing are also included.

Gust Acoustics Computation with a Space-Time CE/SE Parallel 3D Solver

NASA Technical Reports Server (NTRS)

Wang, X. Y.; Himansu, A.; Chang, S. C.; Jorgenson, P. C. E.; Reddy, D. R. (Technical Monitor)

2002-01-01

The benchmark Problem 2 in Category 3 of the Third Computational Aero-Acoustics (CAA) Workshop is solved using the space-time conservation element and solution element (CE/SE) method. This problem concerns the unsteady response of an isolated finite-span swept flat-plate airfoil bounded by two parallel walls to an incident gust. The acoustic field generated by the interaction of the gust with the flat-plate airfoil is computed by solving the 3D (three-dimensional) Euler equations in the time domain using a parallel version of a 3D CE/SE solver. The effect of the gust orientation on the far-field directivity is studied. Numerical solutions are presented and compared with analytical solutions, showing a reasonable agreement.

Preliminary vibration, acoustic, and shock design and test criteria for components on the SRB, ET, and SSME

NASA Technical Reports Server (NTRS)

1976-01-01

Specifications for vibration, acoustic and shock design for components and subassemblies on the External Tank (ET), Solid Rocket Booster (SRB), and Space Shuttle Main Engine (SSME). Included are vibration, acoustic, shock, transportation, handling, and acceptance test requirements and procedures. The space shuttle ET, SRB, and SSME have been divided into zones and subzones. Zones are designated primarily to assist in determining the applicable specifications. A subzone (General Specification) is available for use when the location of the component is known but component design and weight are not well defined. When the location, weight, and mounting configuration of the component are known, specifications for appropriate subzone weight ranges are available. Criteria for some specific components are also presented.

Of drops and bubbles - The technology of space processing

NASA Technical Reports Server (NTRS)

Subramanian, R. Shankar

1984-01-01

It is possible to manipulate a large, molten mass of material, such as a glass, aboard an orbital platform using acoustic fields. Attention is presently given to the problem of bubble removal from such a melt; it is desirable to make small bubbles coalesce into larger ones through floating melt rotation, to create an artificial convective field in which the bubbles will move centripetally to the axis of rotation. Computer models of bubble migration have been developed in order to define the operational conditions required aboard such experiment platforms as the Space Shuttle Orbiter.

Evaluation of acoustic testing techniques for spacecraft systems

NASA Technical Reports Server (NTRS)

Cockburn, J. A.

1971-01-01

External acoustic environments, structural responses, noise reductions, and the internal acoustic environments have been predicted for a typical shroud/spacecraft system during lift-off and various critical stages of flight. Spacecraft responses caused by energy transmission from the shroud via mechanical and acoustic paths have been compared and the importance of the mechanical path has been evaluated. Theoretical predictions have been compared extensively with available laboratory and in-flight measurements. Equivalent laboratory acoustic fields for simulation of shroud response during the various phases of flight have been derived and compared in detail. Techniques for varying the time-space correlations of laboratory acoustic fields have been examined, together with methods for varying the time and spatial distribution of acoustic amplitudes. Possible acoustic testing configurations for shroud/spacecraft systems have been suggested and trade-off considerations have been reviewed. The problem of simulating the acoustic environments versus simulating the structural responses has been considered and techniques for testing without the shroud installed have been discussed.

Study for identification of Beneficial Uses of Space (BUS). Volume 2: Technical report. Book 1: Sections 1 through 4. [with emphasis on space manufacturing and product development

NASA Technical Reports Server (NTRS)

1973-01-01

Consolidated information is presented for the study whose purpose was to identify products, processes, and services to be produced in future spacecraft environments for direct utilization on earth. Discussion of methodology for selecting from among potential space processing approaches, definition of requirements for experiments and tests needed to acquire sufficient knowledge for proof testing of selected processes, formulation of research and development schedules to achieve proof testing, and documentation of the decision processes involved in the programs are presented. Technology and programmatics are reported for the following select studies: (1) surface acoustic wave components; (2) transparent oxides; (3) high purity tungsten X-ray targets; and (4) high specificity isoenzymes.

Structural Dynamic Assessment of the GN2 Piping System for NASA's New and Powerful Reverberant Acoustic Test Facility

NASA Technical Reports Server (NTRS)

McNelis, Mark E.; Staab, Lucas D.; Akers, James C.; Hughes, William O.; Chang, Li C.; Hozman, Aron D.; Henry, Michael W.

2012-01-01

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has led the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA from 2007 to 2011. SAIC-Benham has completed construction of a new reverberant acoustic test facility to support the future testing needs of NASA's space exploration program and commercial customers. The large Reverberant Acoustic Test Facility (RATF) is approximately 101,000 cubic feet in volume and was designed to operate at a maximum empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. Initial checkout acoustic testing was performed on March 2011 by SAIC-Benham at test levels up to 161 dB OASPL. During testing, several branches of the gaseous nitrogen (GN2) piping system, which supply the fluid to the noise generating acoustic modulators, failed at their T-junctions connecting the 12 in. supply line to their respective 4 in. branch lines. The problem was initially detected when the oxygen sensors in the horn room indicated a lower than expected oxygen level from which was inferred GN2 leaks in the piping system. In subsequent follow up inspections, cracks were identified in the failed T-junction connections through non-destructive evaluation testing. Through structural dynamic modeling of the piping system, the root cause of the T-junction connection failures was determined. The structural dynamic assessment identified several possible corrective design improvements to the horn room piping system. The effectiveness of the chosen design repairs were subsequently evaluated in September 2011 during acoustic verification testing to 161 dB OASPL.

Structural Dynamic Assessment of the GN2 Piping System for NASA's New and Powerful Reverberant Acoustic Test Facility

NASA Technical Reports Server (NTRS)

McNelis, Mark E.; Staab, Lucas D.; Akers, James C.; Hughes, WIlliam O.; Chang, Li, C.; Hozman, Aron D.; Henry, Michael W.

2012-01-01

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has led the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA from 2007-2011. SAIC-Benham has completed construction of a new reverberant acoustic test facility to support the future testing needs of NASA's space exploration program and commercial customers. The large Reverberant Acoustic Test Facility (RATF) is approximately 101,000 cu ft in volume and was designed to operate at a maximum empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world's known active reverberant acoustic test facilities. Initial checkout acoustic testing was performed on March 2011 by SAIC-Benham at test levels up to 161 dB OASPL. During testing, several branches of the gaseous nitrogen (GN2) piping system, which supply the fluid to the noise generating acoustic modulators, failed at their "t-junctions" connecting the 12 inch supply line to their respective 4 inch branch lines. The problem was initially detected when the oxygen sensors in the horn room indicated a lower than expected oxygen level from which was inferred GN2 leaks in the piping system. In subsequent follow up inspections, cracks were identified in the failed "t-junction" connections through non-destructive evaluation testing . Through structural dynamic modeling of the piping system, the root cause of the "t-junction" connection failures was determined. The structural dynamic assessment identified several possible corrective design improvements to the horn room piping system. The effectiveness of the chosen design repairs were subsequently evaluated in September 2011 during acoustic verification testing to 161 dB OASPL.

Wake Shield Facility Modal Survey Test in Vibration Acoustic Test Facility

NASA Image and Video Library

1991-10-09

Astronaut Ronald M. Sega stands beside the University of Houston's Wake Shield Facility before it undergoes a Modal Survey Test in the Vibration and Acoustic Test Facility Building 49, prior to being flown on space shuttle mission STS-60.

Bifurcation of space-charge wave in a plasma waveguide including the wake potential effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr

The wake potential effects on the propagation of the space-charge dust ion-acoustic wave are investigated in a cylindrically bounded dusty plasma with the ion flow. The results show that the wake potential would generate the double frequency modes in a cylindrically bounded dusty plasma. It is found that the upper mode of the wave frequency with the root of higher-order is smaller than that with the root of lower-order in intermediate wave number domains. However, the lower mode of the scaled wave frequency with the root of higher-order is found to be greater than that with the root of lower-order.more » It is found that the influence in the order of the root of the Bessel function on the wave frequency of the space-charge dust-ion-acoustic wave in a cylindrically confined dusty plasma decreases with an increase in the propagation wave number. It is also found that the double frequency modes increase with increasing Mach number due to the ion flow in a cylindrical dusty plasma. In addition, it is found that the upper mode of the group velocity decreases with an increase in the scaled radius of the plasma cylinder. However, it is shown that the lower mode of the scaled group velocity of the space-charge dust ion acoustic wave increases with an increase in the radius of the plasma cylinder. The variation of the space-charge dust-ion-acoustic wave due to the wake potential and geometric effects is also discussed.« less

Design and Calibration of an Electrodynamic Driver for the Space Thermoacoustic Refrigerator

DTIC Science & Technology

1989-06-01

University, 1982 Submitted in partial fulfillment of the requirements for the degree of MAST£et OF SCIENCE IN ENGINEERING ACOUSTICS from the NAVAL...A5oustickAcademic Committee Gordon E. Schacher Dean of Science and Engineering ii ABSTRACT The objective of the STAR project is to test and space qualify a...definition of the subject matter to the study of heat engines in which a net 1 heat transport in some gaseous medium is related to the acoustic

Space Shuttle Orbiter audio subsystem. [to communication and tracking system

NASA Technical Reports Server (NTRS)

Stewart, C. H.

1978-01-01

The selection of the audio multiplex control configuration for the Space Shuttle Orbiter audio subsystem is discussed and special attention is given to the evaluation criteria of cost, weight and complexity. The specifications and design of the subsystem are described and detail is given to configurations of the audio terminal and audio central control unit (ATU, ACCU). The audio input from the ACCU, at a signal level of -12.2 to 14.8 dBV, nominal range, at 1 kHz, was found to have balanced source impedance and a balanced local impedance of 6000 + or - 600 ohms at 1 kHz, dc isolated. The Lyndon B. Johnson Space Center (JSC) electroacoustic test laboratory, an audio engineering facility consisting of a collection of acoustic test chambers, analyzed problems of speaker and headset performance, multiplexed control data coupled with audio channels, and the Orbiter cabin acoustic effects on the operational performance of voice communications. This system allows technical management and project engineering to address key constraining issues, such as identifying design deficiencies of the headset interface unit and the assessment of the Orbiter cabin performance of voice communications, which affect the subsystem development.

Space Launch System Scale Model Acoustic Test Ignition Overpressure Testing

NASA Technical Reports Server (NTRS)

Nance, Donald K.; Liever, Peter A.

2015-01-01

The overpressure phenomenon is a transient fluid dynamic event occurring during rocket propulsion system ignition. This phenomenon results from fluid compression of the accelerating plume gas, subsequent rarefaction, and subsequent propagation from the exhaust trench and duct holes. The high-amplitude unsteady fluid-dynamic perturbations can adversely affect the vehicle and surrounding structure. Commonly known as ignition overpressure (IOP), this is an important design-to environment for the Space Launch System (SLS) that NASA is currently developing. Subscale testing is useful in validating and verifying the IOP environment. This was one of the objectives of the Scale Model Acoustic Test (SMAT), conducted at Marshall Space Flight Center (MSFC). The test data quantifies the effectiveness of the SLS IOP suppression system and improves the analytical models used to predict the SLS IOP environments. The reduction and analysis of the data gathered during the SMAT IOP test series requires identification and characterization of multiple dynamic events and scaling of the event waveforms to provide the most accurate comparisons to determine the effectiveness of the IOP suppression systems. The identification and characterization of the overpressure events, the waveform scaling, the computation of the IOP suppression system knockdown factors, and preliminary comparisons to the analytical models are discussed.

Experimental and theoretical study of Rayleigh-Lamb wave propagation

NASA Technical Reports Server (NTRS)

Rogers, Wayne P.; Datta, Subhendu K.; Ju, T. H.

1990-01-01

Many space structures, such as the Space Station Freedom, contain critical thin-walled components. The structural integrity of thin-walled plates and shells can be monitored effectively using acoustic emission and ultrasonic testing in the Rayleigh-Lamb wave frequency range. A new PVDF piezoelectric sensor has been developed that is well suited to remote, inservice nondestructive evaluation of space structures. In the present study the new sensor was used to investigate Rayleigh-Lamb wave propagation in a plate. The experimental apparatus consisted of a glass plate (2.3 m x 25.4 mm x 5.6 mm) with PVDF sensor (3 mm diam.) mounted at various positions along its length. A steel ball impact served as a simulated acoustic emission source, producing surface waves, shear waves and longitudinal waves with dominant frequencies between 1 kHz and 200 kHz. The experimental time domain wave-forms were compared with theoretical predictions of the wave propagation in the plate. The model uses an analytical solution for the Green's function and the measured response at a single position to predict response at any other position in the plate. Close agreement was found between the experimental and theoretical results.

Space Launch System Scale Model Acoustic Test Ignition Overpressure Testing

NASA Technical Reports Server (NTRS)

Nance, Donald; Liever, Peter; Nielsen, Tanner

2015-01-01

The overpressure phenomenon is a transient fluid dynamic event occurring during rocket propulsion system ignition. This phenomenon results from fluid compression of the accelerating plume gas, subsequent rarefaction, and subsequent propagation from the exhaust trench and duct holes. The high-amplitude unsteady fluid-dynamic perturbations can adversely affect the vehicle and surrounding structure. Commonly known as ignition overpressure (IOP), this is an important design-to environment for the Space Launch System (SLS) that NASA is currently developing. Subscale testing is useful in validating and verifying the IOP environment. This was one of the objectives of the Scale Model Acoustic Test, conducted at Marshall Space Flight Center. The test data quantifies the effectiveness of the SLS IOP suppression system and improves the analytical models used to predict the SLS IOP environments. The reduction and analysis of the data gathered during the SMAT IOP test series requires identification and characterization of multiple dynamic events and scaling of the event waveforms to provide the most accurate comparisons to determine the effectiveness of the IOP suppression systems. The identification and characterization of the overpressure events, the waveform scaling, the computation of the IOP suppression system knockdown factors, and preliminary comparisons to the analytical models are discussed.

Gas hydrate saturation from acoustic impedance and resistivity logs in the shenhu area, south china sea

USGS Publications Warehouse

Wang, X.; Wu, S.; Lee, M.; Guo, Y.; Yang, S.; Liang, J.

2011-01-01

During the China's first gas hydrate drilling expedition -1 (GMGS-1), gas hydrate was discovered in layers ranging from 10 to 25 m above the base of gas hydrate stability zone in the Shenhu area, South China Sea. Water chemistry, electrical resistivity logs, and acoustic impedance were used to estimate gas hydrate saturations. Gas hydrate saturations estimated from the chloride concentrations range from 0 to 43% of the pore space. The higher gas hydrate saturations were present in the depth from 152 to 177 m at site SH7 and from 190 to 225 m at site SH2, respectively. Gas hydrate saturations estimated from the resistivity using Archie equation have similar trends to those from chloride concentrations. To examine the variability of gas hydrate saturations away from the wells, acoustic impedances calculated from the 3 D seismic data using constrained sparse inversion method were used. Well logs acquired at site SH7 were incorporated into the inversion by establishing a relation between the water-filled porosity, calculated using gas hydrate saturations estimated from the resistivity logs, and the acoustic impedance, calculated from density and velocity logs. Gas hydrate saturations estimated from acoustic impedance of seismic data are ???10-23% of the pore space and are comparable to those estimated from the well logs. The uncertainties in estimated gas hydrate saturations from seismic acoustic impedances were mainly from uncertainties associated with inverted acoustic impedance, the empirical relation between the water-filled porosities and acoustic impedances, and assumed background resistivity. ?? 2011 Elsevier Ltd.

Benefits of Swept and Leaned Stators for Fan Noise Reduction

NASA Technical Reports Server (NTRS)

Woodward, Richard P.; Elliott, David M.; Hughes, Christopher E.; Berton, Jeffrey J.

1998-01-01

An advanced high bypass ratio fan model was tested in the NASA Lewis Research Center 9 x 15-Foot Low Speed Wind Tunnel. The primary focus of this test was to quantify the acoustic benefits and aerodynamic performance of sweep and lean in stator vane design. Three stator sets were used for this test series. A conventional radial stator was tested at two rotor-stator axial spacings. Additional stator sets incorporating sweep + lean, and sweep only were also tested. The hub axial location for the swept + lean, and sweep only stators corresponded to the location of the radial stator at the upstream rotor-stator spacing, while the tip axial location of these modified stators corresponded to the radial stator axial position at the downstream position. The acoustic results show significant reductions in both rotor-stator interaction noise and broadband noise beyond what could be achieved through increased axial spacing of the conventional, radial stator. Theoretical application of these results to acoustically quantify a fictitious 2-engine aircraft and flight path suggested that about 3 Effective Perceived Noise (EPN) dB could be achieved through incorporation of these modified stators. This reduction would represent a significant portion of the 6 EPNdB noise goal of the current NASA Advanced Subsonic Technology (AST) initiative relative to that of 1992 technology levels. A secondary result of this fan test was to demonstrate the ability of an acoustic barrier wall to block aft-radiated fan noise in the wind tunnel, thus revealing the acoustic structure of the residual inlet-radiated noise. This technology should prove valuable toward better understanding inlet liner design, or wherever it is desirable to eliminate aft-radiated noise from the fan acoustic signature.

Verification tests of durable TPS concepts

NASA Technical Reports Server (NTRS)

Shideler, J. L.; Webb, G. L.; Pittman, C. M.

1984-01-01

Titanium multiwall, superalloy honeycomb, and Advanced Carbon-carbon (ACC) multipost Thermal Protection System (TPS) concepts are being developed to provide durable protection for surfaces of future space transportation systems. Verification tests including thermal, vibration, acoustic, water absorption, lightning strike, and aerothermal tests are described. Preliminary results indicate that the three TPS concepts are viable up to a surface temperature in excess of 2300 F.

Applications of active adaptive noise control to jet engines

NASA Technical Reports Server (NTRS)

Shoureshi, Rahmat; Brackney, Larry

1993-01-01

During phase 2 research on the application of active noise control to jet engines, the development of multiple-input/multiple-output (MIMO) active adaptive noise control algorithms and acoustic/controls models for turbofan engines were considered. Specific goals for this research phase included: (1) implementation of a MIMO adaptive minimum variance active noise controller; and (2) turbofan engine model development. A minimum variance control law for adaptive active noise control has been developed, simulated, and implemented for single-input/single-output (SISO) systems. Since acoustic systems tend to be distributed, multiple sensors, and actuators are more appropriate. As such, the SISO minimum variance controller was extended to the MIMO case. Simulation and experimental results are presented. A state-space model of a simplified gas turbine engine is developed using the bond graph technique. The model retains important system behavior, yet is of low enough order to be useful for controller design. Expansion of the model to include multiple stages and spools is also discussed.

Virtual environment display for a 3D audio room simulation

NASA Astrophysics Data System (ADS)

Chapin, William L.; Foster, Scott

1992-06-01

Recent developments in virtual 3D audio and synthetic aural environments have produced a complex acoustical room simulation. The acoustical simulation models a room with walls, ceiling, and floor of selected sound reflecting/absorbing characteristics and unlimited independent localizable sound sources. This non-visual acoustic simulation, implemented with 4 audio ConvolvotronsTM by Crystal River Engineering and coupled to the listener with a Poihemus IsotrakTM, tracking the listener's head position and orientation, and stereo headphones returning binaural sound, is quite compelling to most listeners with eyes closed. This immersive effect should be reinforced when properly integrated into a full, multi-sensory virtual environment presentation. This paper discusses the design of an interactive, visual virtual environment, complementing the acoustic model and specified to: 1) allow the listener to freely move about the space, a room of manipulable size, shape, and audio character, while interactively relocating the sound sources; 2) reinforce the listener's feeling of telepresence into the acoustical environment with visual and proprioceptive sensations; 3) enhance the audio with the graphic and interactive components, rather than overwhelm or reduce it; and 4) serve as a research testbed and technology transfer demonstration. The hardware/software design of two demonstration systems, one installed and one portable, are discussed through the development of four iterative configurations. The installed system implements a head-coupled, wide-angle, stereo-optic tracker/viewer and multi-computer simulation control. The portable demonstration system implements a head-mounted wide-angle, stereo-optic display, separate head and pointer electro-magnetic position trackers, a heterogeneous parallel graphics processing system, and object oriented C++ program code.

Finite Difference Modeling of Wave Progpagation in Acoustic TiltedTI Media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Linbin; Rector III, James W.; Hoversten, G. Michael

2005-03-21

Based on an acoustic assumption (shear wave velocity is zero) and a dispersion relation, we derive an acoustic wave equation for P-waves in tilted transversely isotropic (TTI) media (transversely isotropic media with a tilted symmetry axis). This equation has fewer parameters than an elastic wave equation in TTI media and yields an accurate description of P-wave traveltimes and spreading-related attenuation. Our TTI acoustic wave equation is a fourth-order equation in time and space. We demonstrate that the acoustic approximation allows the presence of shear waves in the solution. The substantial differences in traveltime and amplitude between data created using VTImore » and TTI assumptions is illustrated in examples.« less

Acoustic metric of the compressible draining bathtub

NASA Astrophysics Data System (ADS)

Cherubini, C.; Filippi, S.

2011-10-01

The draining bathtub flow, a cornerstone in the theory of acoustic black holes, is here extended to the case of exact solutions for compressible nonviscous flows characterized by a polytropic equation of state. Investigating the analytical configurations obtained for selected values of the polytropic index, it is found that each of them becomes nonphysical at the so called limiting circle. By studying the null geodesics structure of the corresponding acoustic line elements, it is shown that such a geometrical locus coincides with the acoustic event horizon. This region is characterized also by an infinite value of space-time curvature, so the acoustic analogy breaks down there. Possible applications for artificial and natural vortices are finally discussed.

Acoustic controlled rotation and orientation

NASA Technical Reports Server (NTRS)

Barmatz, Martin B. (Inventor); Allen, James L. (Inventor)

1989-01-01

Acoustic energy is applied to a pair of locations spaced about a chamber, to control rotation of an object levitated in the chamber. Two acoustic transducers applying energy of a single acoustic mode, one at each location, can (one or both) serve to levitate the object in three dimensions as well as control its rotation. Slow rotation is achieved by initially establishing a large phase difference and/or pressure ratio of the acoustic waves, which is sufficient to turn the object by more than 45 deg, which is immediately followed by reducing the phase difference and/or pressure ratio to maintain slow rotation. A small phase difference and/or pressure ratio enables control of the angular orientation of the object without rotating it. The sphericity of an object can be measured by its response to the acoustic energy.

Tool for Movable Ceiling

NASA Technical Reports Server (NTRS)

1976-01-01

The Bendix Corp., with the help of NASA's Kennedy Space Center, developed a tool to equalize tensions in the 150 cables of the ceiling. This inexpensive tool used in concert halls was developed first for elevator and crane cables used to lift heavy space vehicles. University of Akron's performing arts hall has been developed to shrink and expand to accommodate audiences as large as 3,000 and as small as 900. Once the hall has been sound tuned, various positions of this ingenious ceiling and related acoustic curtains may be called into play immediately by pushing buttons on a control console programmed previously. With the touch of a finger before an event, a technician may condition the hall for chamber music, symphony, or theater.

A digital control system for high level acoustic noise generation

NASA Technical Reports Server (NTRS)

Lee, John P.; Bosco, Jerry H.

1986-01-01

As part of the modernization of the Acoustic Test Facility at Lockheed Missiles and Space Company, Sunnyvale, a digital acoustic control system was designed and built. The requirements imposed by Lockheed on the control system and the degree to which those requirements were met are discussed. Acceptance test results as well as some of the features of the digital control system not found in traditional manual control systems are discussed.

NASA LeRC's Acoustic Fill Effect Test Program and Results

NASA Technical Reports Server (NTRS)

Hughes, William O.; Mcnelis, Mark E.; Manning, Jerome E.

1994-01-01

NASA Lewis Research Center, in conjunction with General Dynamics Space Systems Division, has performed a test program to investigate the acoustic fill effect for an unblanketed payload fairing for a variety of payload simulators. This paper will discuss this test program and fill factor test data, and make comparisons with theoretical predictions. This paper will also address the NASA acoustic fill effect standard which was verified from the test data analysis.

Scale Model Experiments on Sound Propagation From a Mach 2.5 Cold Nitrogen Jet Flowing Through a Rigid-Walled Duct With a J-Deflector

NASA Technical Reports Server (NTRS)

Kandula, Max; Vu, Bruce

2003-01-01

The Launch Systems Testbed (LST) represents the evolution of vibroacoustics research and development work performed at NASA John F. Kennedy Space Center (KSC) over the last 15 years. The LST is located at the Launch Equipment Test Facility (LETF) in the KSC industrial complex. The LETF is operated by Sierra Lobo, Inc., as a member of University-Affiliated Technology Development Contract (USTDC) to KSC Spaceport and Engineering and Technology Directorate (YA), with ASRC Aerospace Corporation as a the prime contractor. Trajectory Simulation Mechanism (TSM) is a major component of the LST, developed specifically to simulate nonstationary acoustic loads on launch pad structures, vehicles, and payloads. TSM enhances the capabilities within LST for simulating launch environments of future vehicles. The scaled launch environments will be used to predict the full-scale launch environment via an appropriate scaling procedure. Air Force Research Laboratory (AFRL) has tasked NASA KSC to perform a basic technology test program in support of developing a low-cost clean pad (incorporating passive mitigation techniques) for future launch vehicles. The overall goal of the program is to develop innovative launch exhaust management systems, which effectively reduce launch acoustic environment with innovative duct designs, while eliminating traditional sound suppression water systems. Passive techniques, such as nontraditional duct geometries, resonators, and diffusers, etc., will be investigated. The overall goals are to advance innovative concepts for a clean pad while developing ideas to reduce transmitted sound via investigation and modeling of jet exhaust acoustic and flow field characteristics. The series of tests outlined in this report represent baseline tests and are geared towards defining the acoustic load environment on the TSM pad for open and closed duct configurations. This report summarizes the cold jet acoustic testing for Mach 2.5 supersonic nitrogen jet issuing from a nozzle with 1-inch exit diameter. Acoustic data, including spectral sound power and Overall Sound Pressure Level (OASPL), are obtained both for a free jet and with the jet flowing through a rigid-walled duct with a J-deflector. The relative performance of closed duct and open duct is evaluated. The results show that the closed duct is superior to the partially open duct, and results in about 3-decibel (dB) noise reduction (near the duct axis) relative to the free jet. The location of the nozzle exit plane (NEP) relative to the duct inlet plane (DIP) has a significant effect on the acoustic field. The results suggest that the location of NEP at 10 inches above the DIP results in reduced acoustic loads relative to 5 inches above the duct inlet and 1 inch into the duct inlet.

Broadband acoustic focusing by Airy-like beams based on acoustic metasurfaces

NASA Astrophysics Data System (ADS)

Chen, Di-Chao; Zhu, Xing-Feng; Wei, Qi; Wu, Da-Jian; Liu, Xiao-Jun

2018-01-01

An acoustic metasurface (AM) composed of space-coiling subunits is proposed to generate acoustic Airy-like beams (ALBs) by manipulating the transmitted acoustic phase. The self-accelerating, self-healing, and non-diffracting features of ALBs are demonstrated using finite element simulations. We further employ two symmetrical AMs to realize two symmetrical ALBs, resulting in highly efficient acoustic focusing. At the working frequency, the focal intensity can reach roughly 20 times that of the incident wave. It is found that the highly efficient acoustic focusing can circumvent obstacles in the propagating path and can be maintained in a broad frequency bandwidth. In addition, simply changing the separation between the two AMs can modulate the focal length of the proposed AM lens. ALBs generated by AMs and the corresponding AM lens may benefit applications in medical ultrasound imaging, biomedical therapy, and particle trapping and manipulation.

Space vehicle acoustics prediction improvement for payloads. [space shuttle

NASA Technical Reports Server (NTRS)

Dandridge, R. E.

1979-01-01

The modal analysis method was extensively modified for the prediction of space vehicle noise reduction in the shuttle payload enclosure, and this program was adapted to the IBM 360 computer. The predicted noise reduction levels for two test cases were compared with experimental results to determine the validity of the analytical model for predicting space vehicle payload noise environments in the 10 Hz one-third octave band regime. The prediction approach for the two test cases generally gave reasonable magnitudes and trends when compared with the measured noise reduction spectra. The discrepancies in the predictions could be corrected primarily by improved modeling of the vehicle structural walls and of the enclosed acoustic space to obtain a more accurate assessment of normal modes. Techniques for improving and expandng the noise prediction for a payload environment are also suggested.

Articulatory-acoustic vowel space: application to clear speech in individuals with Parkinson's disease.

PubMed

Whitfield, Jason A; Goberman, Alexander M

2014-01-01

Individuals with Parkinson disease (PD) often exhibit decreased range of movement secondary to the disease process, which has been shown to affect articulatory movements. A number of investigations have failed to find statistically significant differences between control and disordered groups, and between speaking conditions, using traditional vowel space area measures. The purpose of the current investigation was to evaluate both between-group (PD versus control) and within-group (habitual versus clear) differences in articulatory function using a novel vowel space measure, the articulatory-acoustic vowel space (AAVS). The novel AAVS is calculated from continuously sampled formant trajectories of connected speech. In the current study, habitual and clear speech samples from twelve individuals with PD along with habitual control speech samples from ten neurologically healthy adults were collected and acoustically analyzed. In addition, a group of listeners completed perceptual rating of speech clarity for all samples. Individuals with PD were perceived to exhibit decreased speech clarity compared to controls. Similarly, the novel AAVS measure was significantly lower in individuals with PD. In addition, the AAVS measure significantly tracked changes between the habitual and clear conditions that were confirmed by perceptual ratings. In the current study, the novel AAVS measure is shown to be sensitive to disease-related group differences and within-person changes in articulatory function of individuals with PD. Additionally, these data confirm that individuals with PD can modulate the speech motor system to increase articulatory range of motion and speech clarity when given a simple prompt. The reader will be able to (i) describe articulatory behavior observed in the speech of individuals with Parkinson disease; (ii) describe traditional measures of vowel space area and how they relate to articulation; (iii) describe a novel measure of vowel space, the articulatory-acoustic vowel space and its relationship to articulation and the perception of speech clarity. Copyright © 2014 Elsevier Inc. All rights reserved.

Acoustic Source Localization in Aircraft Interiors Using Microphone Array Technologies

NASA Technical Reports Server (NTRS)

Sklanka, Bernard J.; Tuss, Joel R.; Buehrle, Ralph D.; Klos, Jacob; Williams, Earl G.; Valdivia, Nicolas

2006-01-01

Using three microphone array configurations at two aircraft body stations on a Boeing 777-300ER flight test, the acoustic radiation characteristics of the sidewall and outboard floor system are investigated by experimental measurement. Analysis of the experimental data is performed using sound intensity calculations for closely spaced microphones, PATCH Inverse Boundary Element Nearfield Acoustic Holography, and Spherical Nearfield Acoustic Holography. Each method is compared assessing strengths and weaknesses, evaluating source identification capability for both broadband and narrowband sources, evaluating sources during transient and steady-state conditions, and quantifying field reconstruction continuity using multiple array positions.

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.

Hawking radiation and classical tunneling: A ray phase space approach

NASA Astrophysics Data System (ADS)

Tracy, E. R.; Zhigunov, D.

2016-01-01

Acoustic waves in fluids undergoing the transition from sub- to supersonic flow satisfy governing equations similar to those for light waves in the immediate vicinity of a black hole event horizon. This acoustic analogy has been used by Unruh and others as a conceptual model for "Hawking radiation." Here, we use variational methods, originally introduced by Brizard for the study of linearized MHD, and ray phase space methods, to analyze linearized acoustics in the presence of background flows. The variational formulation endows the evolution equations with natural Hermitian and symplectic structures that prove useful for later analysis. We derive a 2 × 2 normal form governing the wave evolution in the vicinity of the "event horizon." This shows that the acoustic model can be reduced locally (in ray phase space) to a standard (scalar) tunneling process weakly coupled to a unidirectional non-dispersive wave (the "incoming wave"). Given the normal form, the Hawking "thermal spectrum" can be derived by invoking standard tunneling theory, but only by ignoring the coupling to the incoming wave. Deriving the normal form requires a novel extension of the modular ray-based theory used previously to study tunneling and mode conversion in plasmas. We also discuss how ray phase space methods can be used to change representation, which brings the problem into a form where the wave functions are less singular than in the usual formulation, a fact that might prove useful in numerical studies.

Development and Validation of an Interactive Liner Design and Impedance Modeling Tool

NASA Technical Reports Server (NTRS)

Howerton, Brian M.; Jones, Michael G.; Buckley, James L.

2012-01-01

The Interactive Liner Impedance Analysis and Design (ILIAD) tool is a LabVIEW-based software package used to design the composite surface impedance of a series of small-diameter quarter-wavelength resonators incorporating variable depth and sharp bends. Such structures are useful for packaging broadband acoustic liners into constrained spaces for turbofan engine noise control applications. ILIAD s graphical user interface allows the acoustic channel geometry to be drawn in the liner volume while the surface impedance and absorption coefficient calculations are updated in real-time. A one-dimensional transmission line model serves as the basis for the impedance calculation and can be applied to many liner configurations. Experimentally, tonal and broadband acoustic data were acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3000 Hz at 120 and 140 dB SPL. Normalized impedance spectra were measured using the Two-Microphone Method for the various combinations of channel configurations. Comparisons between the computed and measured impedances show excellent agreement for broadband liners comprised of multiple, variable-depth channels. The software can be used to design arrays of resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment.

The binaural performance of a cross-talk cancellation system with matched or mismatched setup and playback acoustics

PubMed Central

Akeroyd, Michael A.; Chambers, John; Bullock, David; Palmer, Alan R.; Summerfield, A. Quentin; Nelson, Philip A.; Gatehouse, Stuart

2013-01-01

Cross-talk cancellation is a method for synthesising virtual auditory space using loudspeakers. One implementation is the “Optimal Source Distribution” technique [T. Takeuchi and P. Nelson, J. Acoust. Soc. Am. 112, 2786-2797 (2002)], in which the audio bandwidth is split across three pairs of loudspeakers, placed at azimuths of ±90°, ±15°, and ±3°, conveying low, mid and high frequencies, respectively. A computational simulation of this system was developed and verified against measurements made on an acoustic system using a manikin. Both the acoustic system and the simulation gave a wideband average cancellation of almost 25 dB. The simulation showed that when there was a mismatch between the head-related transfer functions used to set up the system and those of the final listener, the cancellation was reduced to an average of 13 dB. Moreover, in this case the binaural ITDs and ILDs delivered by the simulation of the OSD system often differed from the target values. It is concluded that only when the OSD system is set up with “matched” head-related transfer functions can it deliver accurate binaural cues. PMID:17348528

Numerical Simulation of the Self-Oscillations of the Vocal Folds and of the Resulting Acoustic Phenomena in the Vocal Tract

NASA Astrophysics Data System (ADS)

Švancara, P.; Horáček, J.; Švec, J. G.

The study presents a three-dimensional (3D) finite element (FE) model of the flow-induced self-oscillation of the human vocal folds in interaction with acoustics of simplified vocal tract models. The 3D vocal tract models of the acoustic spaces shaped for simulation of phonation of Czech vowels [a:], [i:] and [u:] were created by converting the data from the magnetic resonance images (MRI). For modelling of the fluid-structure interaction, explicit coupling scheme with separated solvers for fluid and structure domain was utilized. The FE model comprises vocal folds pretension before starting phonation, large deformations of the vocal fold tissue, vocal-fold collisions, fluid-structure interaction, morphing the fluid mesh according to the vocal-fold motion (Arbitrary Lagrangian-Eulerian approach), unsteady viscous compressible airflow described by the Navier-Stokes equations and airflow separation. The developed FE model enables to study the relationship between flow-induced vibrations of the vocal folds and acoustic wave propagation in the vocal tract and can also be used to simulate for example pathological changes in the vocal fold tissue and their influence on the voice production.

The binaural performance of a cross-talk cancellation system with matched or mismatched setup and playback acoustics.

PubMed

Akeroyd, Michael A; Chambers, John; Bullock, David; Palmer, Alan R; Summerfield, A Quentin; Nelson, Philip A; Gatehouse, Stuart

2007-02-01

Cross-talk cancellation is a method for synthesizing virtual auditory space using loudspeakers. One implementation is the "Optimal Source Distribution" technique [T. Takeuchi and P. Nelson, J. Acoust. Soc. Am. 112, 2786-2797 (2002)], in which the audio bandwidth is split across three pairs of loudspeakers, placed at azimuths of +/-90 degrees, +/-15 degrees, and +/-3 degrees, conveying low, mid, and high frequencies, respectively. A computational simulation of this system was developed and verified against measurements made on an acoustic system using a manikin. Both the acoustic system and the simulation gave a wideband average cancellation of almost 25 dB. The simulation showed that when there was a mismatch between the head-related transfer functions used to set up the system and those of the final listener, the cancellation was reduced to an average of 13 dB. Moreover, in this case the binaural interaural time differences and interaural level differences delivered by the simulation of the optimal source distribution (OSD) system often differed from the target values. It is concluded that only when the OSD system is set up with "matched" head-related transfer functions can it deliver accurate binaural cues.

Extinction cross-section cancellation of a cylindrical radiating active source near a rigid corner and acoustic invisibility

NASA Astrophysics Data System (ADS)

Mitri, F. G.

2017-11-01

Active cloaking in its basic form requires that the extinction cross-section (or energy efficiency) from a radiating body vanishes. In this analysis, this physical effect is demonstrated for an active cylindrically radiating acoustic source in a non-viscous fluid, undergoing periodic axisymmetric harmonic vibrations near a rigid corner (i.e., quarter-space). The rigorous multipole expansion method in cylindrical coordinates, the method of images, and the addition theorem of cylindrical wave functions are used to derive closed-form mathematical expressions for the radiating, amplification, and extinction cross-sections of the active source. Numerical computations are performed assuming monopole and dipole modal oscillations of the circular source. The results reveal some of the situations where the extinction energy efficiency factor of the active source vanishes depending on its size and location with respect to the rigid corner, thus, achieving total invisibility. Moreover, the extinction energy efficiency factor varies between positive or negative values. These effects also occur for higher-order modal oscillations of the active source. The results find potential applications in the development of acoustic cloaking devices and invisibility in underwater acoustics or other areas.

From prosodic structure to acoustic saliency: A fMRI investigation of speech rate, clarity, and emphasis

NASA Astrophysics Data System (ADS)

Golfinopoulos, Elisa

Acoustic variability in fluent speech can arise at many stages in speech production planning and execution. For example, at the phonological encoding stage, the grouping of phonemes into syllables determines which segments are coarticulated and, by consequence, segment-level acoustic variation. Likewise phonetic encoding, which determines the spatiotemporal extent of articulatory gestures, will affect the acoustic detail of segments. Functional magnetic resonance imaging (fMRI) was used to measure brain activity of fluent adult speakers in four speaking conditions: fast, normal, clear, and emphatic (or stressed) speech. These speech manner changes typically result in acoustic variations that do not change the lexical or semantic identity of productions but do affect the acoustic saliency of phonemes, syllables and/or words. Acoustic responses recorded inside the scanner were assessed quantitatively using eight acoustic measures and sentence duration was used as a covariate of non-interest in the neuroimaging analysis. Compared to normal speech, emphatic speech was characterized acoustically by a greater difference between stressed and unstressed vowels in intensity, duration, and fundamental frequency, and neurally by increased activity in right middle premotor cortex and supplementary motor area, and bilateral primary sensorimotor cortex. These findings are consistent with right-lateralized motor planning of prosodic variation in emphatic speech. Clear speech involved an increase in average vowel and sentence durations and average vowel spacing, along with increased activity in left middle premotor cortex and bilateral primary sensorimotor cortex. These findings are consistent with an increased reliance on feedforward control, resulting in hyper-articulation, under clear as compared to normal speech. Fast speech was characterized acoustically by reduced sentence duration and average vowel spacing, and neurally by increased activity in left anterior frontal operculum and posterior dorsal inferior frontal gyms pars opercularis -- regions thought to be involved in sequencing and phrase-level structural processing. Taken together these findings identify the acoustic and neural correlates of adjusting speech manner and underscore the different processing stages that can contribute to acoustic variability in fluent sentence production.

Effects of sound source directivity on auralizations

NASA Astrophysics Data System (ADS)

Sheets, Nathan W.; Wang, Lily M.

2002-05-01

Auralization, the process of rendering audible the sound field in a simulated space, is a useful tool in the design of acoustically sensitive spaces. The auralization depends on the calculation of an impulse response between a source and a receiver which have certain directional behavior. Many auralizations created to date have used omnidirectional sources; the effects of source directivity on auralizations is a relatively unexplored area. To examine if and how the directivity of a sound source affects the acoustical results obtained from a room, we used directivity data for three sources in a room acoustic modeling program called Odeon. The three sources are: violin, piano, and human voice. The results from using directional data are compared to those obtained using omnidirectional source behavior, both through objective measure calculations and subjective listening tests.

Effect of sound-related activities on human behaviours and acoustic comfort in urban open spaces.

PubMed

Meng, Qi; Kang, Jian

2016-12-15

Human activities are important to landscape design and urban planning; however, the effect of sound-related activities on human behaviours and acoustic comfort has not been considered. The objective of this study is to explore how human behaviours and acoustic comfort in urban open spaces can be changed by sound-related activities. On-site measurements were performed at a case study site in Harbin, China, and an acoustic comfort survey was simultaneously conducted. In terms of effect of sound activities on human behaviours, music-related activities caused 5.1-21.5% of persons who pass by the area to stand and watch the activity, while there was a little effect on the number of persons who performed excises during the activity. Human activities generally have little effect on the behaviour of pedestrians when only 1 to 3 persons are involved in the activities, while a deep effect on the behaviour of pedestrians is noted when >6 persons are involved in the activities. In terms of effect of activities on acoustic comfort, music-related activities can increase the sound level from 10.8 to 16.4dBA, while human activities such RS and PC can increase the sound level from 9.6 to 12.8dBA; however, they lead to very different acoustic comfort. The acoustic comfort of persons can differ with activities, for example the acoustic comfort of persons who stand watch can increase by music-related activities, while the acoustic comfort of persons who sit and watch can decrease by human sound-related activities. Some sound-related activities can show opposite trend of acoustic comfort between visitors and citizens. Persons with higher income prefer music sound-related activities, while those with lower income prefer human sound-related activities. Copyright © 2016 Elsevier B.V. All rights reserved.

Analytical trade study of the STS payload environment. [design analysis and cost estimates for noise reduction devices for space shuttle orbiter payloads

NASA Technical Reports Server (NTRS)

Rader, W. P.; Barrett, S.; Raratono, J.; Payne, K. R.

1976-01-01

The current predicted acoustic environment for the shuttle orbiter payload bay will produce random vibration environments for payload components and subsystems which potentially will result in design, weight and cost penalties if means of protecting the payloads are not developed. Results are presented of a study to develop, through design and cost effectiveness trade studies, conceptual noise suppression device designs for space shuttle payloads. The impact of noise suppression on environmental levels and associated test costs, and on test philosophy for the various payload classes is considered with the ultimate goal of reducing payload test costs. Conclusions and recommendations are presented.

Spatial Attention Modulates the Precedence Effect

ERIC Educational Resources Information Center

London, Sam; Bishop, Christopher W.; Miller, Lee M.

2012-01-01

Communication and navigation in real environments rely heavily on the ability to distinguish objects in acoustic space. However, auditory spatial information is often corrupted by conflicting cues and noise such as acoustic reflections. Fortunately the brain can apply mechanisms at multiple levels to emphasize target information and mitigate such…

Hear and Now

ERIC Educational Resources Information Center

McKeon, Michael; Berry, Lincoln

2006-01-01

Classrooms often get the short shrift when it comes to designing a space that allows for optimum hearing conditions for students and speaking conditions for teachers. Over the last few years, increasing concern from state regulators and facility designers has focused greater attention on improving acoustics. The main acoustical issues to consider…

Designing a Secondary Music Suite.

ERIC Educational Resources Information Center

Smedstad, Mike

1998-01-01

Discusses four factors in designing a school music room that satisfies student, teacher, and school needs. Explores acoustics in terms of cubic volume, room shape, sound isolation, acoustical treatment, and mechanical systems. Also examines the floorplan for space, traffic control, and access to related areas. Concluding comments address equipment…

Utilization of the k-space Computational Method to Design an Intracavitary Transrectal Ultrasound Phased Array Applicator for Hyperthermia Treatment of Prostate Cancer

NASA Astrophysics Data System (ADS)

Al-Bataineh, Osama M.; Collins, Christopher M.; Sparrow, Victor W.; Keolian, Robert M.; Smith, Nadine Barrie

2006-05-01

This research utilizes the k-space computational method to design an intracavitary probe for hyperthermia treatment of prostate cancer. A three-dimensional (3D) photographical prostate model, utilizing imaging data from the Visible Human Project®, was the basis for inhomogeneous acoustical model development. The acoustical model accounted for sound speed, density, and absorption variations. The k-space computational method was used to simulate ultrasound wave propagation of the designed phased array through the acoustical model. To insure the uniformity and spread of the pressure in the length of the array, and the steering and focusing capability in the width of the array, the equal-sized elements of the phased array were 1 × 14 mm. The anatomical measurements of the prostate were used to predict the final phased array specifications (4 × 20 planar array, 1.2 MHz, element size = 1 × 14 mm, array size = 56 × 20 mm). Good agreement between the exposimetry and the k-space results was achieved. As an example, the -3 dB distances of the focal volume were differing by 9.1% in the propagation direction for k-space prostate simulation and exposimetry results. Temperature simulations indicated that the rectal wall temperature was elevated less than 2°C during hyperthermia treatment. Steering and focusing ability of the designed probe, in both azimuth and propagation directions, were found to span the entire prostate volume with minimal grating lobes (-10 dB reduction from the main lobe) and least heat damage to the rectal wall. Evaluations of the probe included ex vivo and in vivo controlled experiments to deliver the required thermal dose to the targeted tissue. With a desired temperature plateau of 43.0°C, the MRI temperature results at the steady state were 42.9 ± 0.38°C and 43.1 ± 0.80°C for ex vivo and in vivo experiments, respectively. Unlike conventional computational methods, the k-space method provides a powerful tool to predict pressure wavefield and temperature rise in sophisticated, large scale, 3D, inhomogeneous and coarse grid models.

Resonant capacitive MEMS acoustic emission transducers

NASA Astrophysics Data System (ADS)

Ozevin, D.; Greve, D. W.; Oppenheim, I. J.; Pessiki, S. P.

2006-12-01

We describe resonant capacitive MEMS transducers developed for use as acoustic emission (AE) detectors, fabricated in the commercial three-layer polysilicon surface micromachining process (MUMPs). The 1 cm square device contains six independent transducers in the frequency range between 100 and 500 kHz, and a seventh transducer at 1 MHz. Each transducer is a parallel plate capacitor with one plate free to vibrate, thereby causing a capacitance change which creates an output signal in the form of a current under a dc bias voltage. With the geometric proportions we employed, each transducer responds with two distinct resonant frequencies. In our design the etch hole spacing was chosen to limit squeeze film damping and thereby produce an underdamped vibration when operated at atmospheric pressure. Characterization experiments obtained by capacitance and admittance measurements are presented, and transducer responses to physically simulated AE source are discussed. Finally, we report our use of the device to detect acoustic emissions associated with crack initiation and growth in weld metal.

Root finding in the complex plane for seismo-acoustic propagation scenarios with Green's function solutions.

PubMed

McCollom, Brittany A; Collis, Jon M

2014-09-01

A normal mode solution to the ocean acoustic problem of the Pekeris waveguide with an elastic bottom using a Green's function formulation for a compressional wave point source is considered. Analytic solutions to these types of waveguide propagation problems are strongly dependent on the eigenvalues of the problem; these eigenvalues represent horizontal wavenumbers, corresponding to propagating modes of energy. The eigenvalues arise as singularities in the inverse Hankel transform integral and are specified by roots to a characteristic equation. These roots manifest themselves as poles in the inverse transform integral and can be both subtle and difficult to determine. Following methods previously developed [S. Ivansson et al., J. Sound Vib. 161 (1993)], a root finding routine has been implemented using the argument principle. Using the roots to the characteristic equation in the Green's function formulation, full-field solutions are calculated for scenarios where an acoustic source lies in either the water column or elastic half space. Solutions are benchmarked against laboratory data and existing numerical solutions.

Non-Contact Temperature Requirements (NCTM) for drop and bubble physics

NASA Technical Reports Server (NTRS)

Hmelo, Anthony B.; Wang, Taylor G.

1989-01-01

Many of the materials research experiments to be conducted in the Space Processing program require a non-contaminating method of manipulating and controlling weightless molten materials. In these experiments, the melt is positioned and formed within a container without physically contacting the container's wall. An acoustic method, which was developed by Professor Taylor G. Wang before coming to Vanderbilt University from the Jet Propulsion Laboratory, has demonstrated the capability of positioning and manipulating room temperature samples. This was accomplished in an earth-based laboratory with a zero-gravity environment of short duration. However, many important facets of high temperature containerless processing technology have not been established yet, nor can they be established from the room temperature studies, because the details of the interaction between an acoustic field an a molten sample are largely unknown. Drop dynamics, bubble dynamics, coalescence behavior of drops and bubbles, electromagnetic and acoustic levitation methods applied to molten metals, and thermal streaming are among the topics discussed.

Interacting Multiscale Acoustic Vortices as Coherent Excitations in Dust Acoustic Wave Turbulence

NASA Astrophysics Data System (ADS)

Lin, Po-Cheng; I, Lin

2018-03-01

In this work, using three-dimensional intermittent dust acoustic wave turbulence in a dusty plasma as a platform and multidimensional empirical mode decomposition into different-scale modes in the 2 +1 D spatiotemporal space, we demonstrate the experimental observation of the interacting multiscale acoustic vortices, winding around wormlike amplitude hole filaments coinciding with defect filaments, as the basic coherent excitations for acoustic-type wave turbulence. For different decomposed modes, the self-similar rescaled stretched exponential lifetime histograms of amplitude hole filaments, and the self-similar power spectra of dust density fluctuations, indicate that similar dynamical rules are followed over a wide range of scales. In addition to the intermode acoustic vortex pair generation, propagation, or annihilation, the intra- and intermode interactions of acoustic vortices with the same or opposite helicity, their entanglement and synchronization, are found to be the key dynamical processes in acoustic wave turbulence, akin to the interacting multiscale vortices around wormlike cores observed in hydrodynamic turbulence.

Development of a Laboratory for Improving Communication between Air Traffic Controllers and Pilots

NASA Technical Reports Server (NTRS)

Brammer, Anthony

2003-01-01

Runway incursions and other surface incidents are known to be significant threats to aviation safety and efficiency. Though the number of near mid-air collisions in U.S. air space has remained unchanged during the last five years, the number of runway incursions has increased and they are almost all due to human error. The three most common factors contributing to air traffic controller and pilot error in airport operations include two that involve failed auditory communication. This project addressed the problems of auditory communication in air traffic control from an acoustical standpoint, by establishing an acoustics laboratory designed for this purpose and initiating research into selected topics that show promise for improving voice communications between air traffic controllers and pilots.

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.

The Effects of Sediment Properties on Low Frequency Acoustic Propagation

DTIC Science & Technology

2014-09-30

identified in task (a). c. Understanding the effect of ocean acidification on acoustic propagation. The PIs (Miller and Potty) are trying to get funding...the half-space. The properties of the sediment used in the model calculation are shown in the top panel. b. Effect of Ocean Acidification on...Acoustic Propagation: One of the consequences of increasing atmospheric CO2 is ocean acidification . The reduction in pH is a direct result of increased

Flow visualization of acoustic levitation experiment

NASA Technical Reports Server (NTRS)

Baroth, ED

1987-01-01

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

Acoustic Multipurpose Cargo Transfer Bag

NASA Technical Reports Server (NTRS)

Baccus, Shelley

2015-01-01

The Logistics Reduction (LR) project within the Advanced Exploration Systems (AES) program is tasked with reducing logistical mass and repurposing logistical items. Multipurpose Cargo Transfer Bags (MCTB) are designed to be the same external volume as a regular cargo transfer bag, the common logistics carrier for the International Space Station. After use as a cargo bag, the MCTB can be unzipped and unfolded to be reused. This Acoustic MCTBs transform into acoustic blankets after the initial logistics carrying objective is complete.

Heat-driven acoustic cooling engine having no moving parts

DOEpatents

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.

KSC-03pd1385

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - A team onboard the Liberty Star, the NASA Space Shuttle support ship operated by United Space Alliance, get ready to lower underwater research equipment into the water. An undersea expedition is underway to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. The equipment includes an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1384

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - Underwater research equipment is prepared for immersion from the Liberty Star, the NASA Space Shuttle support ship operated by United Space Alliance. It is being used on an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. The equipment includes an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

Optical information processing at NASA Ames Research Center

NASA Technical Reports Server (NTRS)

Reid, Max B.; Bualat, Maria G.; Cho, Young C.; Downie, John D.; Gary, Charles K.; Ma, Paul W.; Ozcan, Meric; Pryor, Anna H.; Spirkovska, Lilly

1993-01-01

The combination of analog optical processors with digital electronic systems offers the potential of tera-OPS computational performance, while often requiring less power and weight relative to all-digital systems. NASA is working to develop and demonstrate optical processing techniques for on-board, real time science and mission applications. Current research areas and applications under investigation include optical matrix processing for space structure vibration control and the analysis of Space Shuttle Main Engine plume spectra, optical correlation-based autonomous vision for robotic vehicles, analog computation for robotic path planning, free-space optical interconnections for information transfer within digital electronic computers, and multiplexed arrays of fiber optic interferometric sensors for acoustic and vibration measurements.

3D reconstruction and spatial auralization of the "Painted Dolmen" of Antelas

NASA Astrophysics Data System (ADS)

Dias, Paulo; Campos, Guilherme; Santos, Vítor; Casaleiro, Ricardo; Seco, Ricardo; Sousa Santos, Beatriz

2008-02-01

This paper presents preliminary results on the development of a 3D audiovisual model of the Anta Pintada (painted dolmen) of Antelas, a Neolithic chamber tomb located in Oliveira de Frades and listed as Portuguese national monument. The final aim of the project is to create a highly accurate Virtual Reality (VR) model of this unique archaeological site, capable of providing not only visual but also acoustic immersion based on its actual geometry and physical properties. The project started in May 2006 with in situ data acquisition. The 3D geometry of the chamber was captured using a Laser Range Finder. In order to combine the different scans into a complete 3D visual model, reconstruction software based on the Iterative Closest Point (ICP) algorithm was developed using the Visualization Toolkit (VTK). This software computes the boundaries of the room on a 3D uniform grid and populates its interior with "free-space nodes", through an iterative algorithm operating like a torchlight illuminating a dark room. The envelope of the resulting set of "free-space nodes" is used to generate a 3D iso-surface approximating the interior shape of the chamber. Each polygon of this surface is then assigned the acoustic absorption coefficient of the corresponding boundary material. A 3D audiovisual model operating in real-time was developed for a VR Environment comprising head-mounted display (HMD) I-glasses SVGAPro, an orientation sensor (tracker) InterTrax 2 with 3 Degrees Of Freedom (3DOF) and stereo headphones. The auralisation software is based on a geometric model. This constitutes a first approach, since geometric acoustics have well-known limitations in rooms with irregular surfaces. The immediate advantage lies in their inherent computational efficiency, which allows real-time operation. The program computes the early reflections forming the initial part of the chamber's impulse response (IR), which carry the most significant cues for source localisation. These early reflections are processed through Head Related Transfer Functions (HRTF) updated in real-time according to the orientation of the user's head, so that sound waves appear to come from the correct location in space, in agreement with the visual scene. The late-reverberation tail of the IR is generated by an algorithm designed to match the reverberation time of the chamber, calculated from the actual acoustic absorption coefficients of its surfaces. The sound output to the headphones is obtained by convolving the IR with anechoic recordings of the virtual audio source.

Cerebellar interaction with the acoustic reflex.

PubMed

Jastreboff, P J

1981-01-01

The involvement of the cerebellar vermis in the acoustic reflex was analyzed in 12 cats, decerebrated or in pentobarbital anesthesia. Anatomical data suggested the existence of a connection of lobules VIII with the ventral cochlear nucleus. Single cell recording and evoked potential techniques demonstrated the existence of the acoustic projection to lobulus VIII. Electrical stimulation of this area changed the tension of the middle ear muscle and caused evoked potential responses in the caudal part of the ventral cochlear nucleus. Electrical stimulation of the motor nucleus of the facial nerve evoked a slow wave in the recording taken from the surrounding of the cochlear round window. A hypothesis is proposed which postulates the involvement of the acoustic reflex in space localization of acoustic stimuli and the action of cerebellar vermis in order to assure the stability and plasticity of the acoustic reflex arc.

Vowel Development in an Emergent Mandarin-English Bilingual Child: A Longitudinal Study

ERIC Educational Resources Information Center

Yang, Jing; Fox, Robert A.; Jacewicz, Ewa

2015-01-01

This longitudinal case study documents the emergence of bilingualism in a young monolingual Mandarin boy on the basis of an acoustic analysis of his vowel productions recorded via a picture-naming task over 20 months following his enrollment in an all-English (L2) preschool at the age of 3;7. The study examined (1) his initial L2 vowel space, (2)…

14 CFR 36.11 - Acoustical change: Helicopters.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Acoustical change: Helicopters. 36.11...: Helicopters. This section applies to all helicopters in the primary, normal, transport, and restricted... appendix H of this part, or, for helicopters having a maximum certificated takeoff weight of not more than...

14 CFR 36.11 - Acoustical change: Helicopters.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Acoustical change: Helicopters. 36.11...: Helicopters. This section applies to all helicopters in the primary, normal, transport, and restricted... appendix H of this part, or, for helicopters having a maximum certificated takeoff weight of not more than...

14 CFR 36.11 - Acoustical change: Helicopters.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Acoustical change: Helicopters. 36.11...: Helicopters. This section applies to all helicopters in the primary, normal, transport, and restricted... appendix H of this part, or, for helicopters having a maximum certificated takeoff weight of not more than...

14 CFR 36.11 - Acoustical change: Helicopters.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Acoustical change: Helicopters. 36.11...: Helicopters. This section applies to all helicopters in the primary, normal, transport, and restricted... appendix H of this part, or, for helicopters having a maximum certificated takeoff weight of not more than...

14 CFR 36.11 - Acoustical change: Helicopters.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Acoustical change: Helicopters. 36.11...: Helicopters. This section applies to all helicopters in the primary, normal, transport, and restricted... appendix H of this part, or, for helicopters having a maximum certificated takeoff weight of not more than...

14 CFR 36.9 - Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category...

Code of Federal Regulations, 2013 CFR

2013-01-01

... airplanes and propeller-driven commuter category airplanes. 36.9 Section 36.9 Aeronautics and Space FEDERAL... AIRWORTHINESS CERTIFICATION General § 36.9 Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes. For propeller-driven small airplanes in the primary, normal, utility...

14 CFR 36.9 - Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category...

Code of Federal Regulations, 2012 CFR

2012-01-01

... airplanes and propeller-driven commuter category airplanes. 36.9 Section 36.9 Aeronautics and Space FEDERAL... AIRWORTHINESS CERTIFICATION General § 36.9 Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes. For propeller-driven small airplanes in the primary, normal, utility...

14 CFR 36.9 - Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category...

Code of Federal Regulations, 2011 CFR

2011-01-01

... airplanes and propeller-driven commuter category airplanes. 36.9 Section 36.9 Aeronautics and Space FEDERAL... AIRWORTHINESS CERTIFICATION General § 36.9 Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes. For propeller-driven small airplanes in the primary, normal, utility...

14 CFR 36.9 - Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category...

Code of Federal Regulations, 2014 CFR

2014-01-01

... airplanes and propeller-driven commuter category airplanes. 36.9 Section 36.9 Aeronautics and Space FEDERAL... AIRWORTHINESS CERTIFICATION General § 36.9 Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes. For propeller-driven small airplanes in the primary, normal, utility...

Sound, Noise, and Vibration Control.

ERIC Educational Resources Information Center

Yerges, Lyle F.

This working guide on the principles and techniques of controlling acoustical environment is discussed in the light of human, environmental and building needs. The nature of sound and its variables are defined. The acoustical environment and its many materials, spaces and functional requirements are described, with specific methods for planning,…

14 CFR 36.9 - Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category...

Code of Federal Regulations, 2010 CFR

2010-01-01

... airplanes and propeller-driven commuter category airplanes. 36.9 Section 36.9 Aeronautics and Space FEDERAL... AIRWORTHINESS CERTIFICATION General § 36.9 Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes. For propeller-driven small airplanes in the primary, normal, utility...

Composite load spectra for select space propulsion structural components

NASA Technical Reports Server (NTRS)

Newell, J. F.; Kurth, R. E.; Ho, H.

1991-01-01

The objective of this program is to develop generic load models with multiple levels of progressive sophistication to simulate the composite (combined) load spectra that are induced in space propulsion system components, representative of Space Shuttle Main Engines (SSME), such as transfer ducts, turbine blades, and liquid oxygen posts and system ducting. The first approach will consist of using state of the art probabilistic methods to describe the individual loading conditions and combinations of these loading conditions to synthesize the composite load spectra simulation. The second approach will consist of developing coupled models for composite load spectra simulation which combine the deterministic models for composite load dynamic, acoustic, high pressure, and high rotational speed, etc., load simulation using statistically varying coefficients. These coefficients will then be determined using advanced probabilistic simulation methods with and without strategically selected experimental data.

An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Articles Absorption During Reverberant Chamber Acoustic Testing of Spaceflight Hardware

NASA Technical Reports Server (NTRS)

Hozman, Aron D.; Hughes, William O.

2014-01-01

It is important to realize that some test-articles may have significant sound absorption that may challenge the acoustic power capabilities of a test facility. Therefore, to mitigate this risk of not being able to meet the customers target spectrum, it is prudent to demonstrate early-on an increased acoustic power capability which compensates for this test-article absorption. This paper describes a concise method to reduce this risk when testing aerospace test-articles which have significant absorption. This method was successfully applied during the SpaceX Falcon 9 Payload Fairing acoustic test program at the NASA Glenn Research Center Plum Brook Stations RATF.

High-Resolution Genuinely Multidimensional Solution of Conservation Laws by the Space-Time Conservation Element and Solution Element Method

NASA Technical Reports Server (NTRS)

Himansu, Ananda; Chang, Sin-Chung; Yu, Sheng-Tao; Wang, Xiao-Yen; Loh, Ching-Yuen; Jorgenson, Philip C. E.

1999-01-01

In this overview paper, we review the basic principles of the method of space-time conservation element and solution element for solving the conservation laws in one and two spatial dimensions. The present method is developed on the basis of local and global flux conservation in a space-time domain, in which space and time are treated in a unified manner. In contrast to the modern upwind schemes, the approach here does not use the Riemann solver and the reconstruction procedure as the building blocks. The drawbacks of the upwind approach, such as the difficulty of rationally extending the 1D scalar approach to systems of equations and particularly to multiple dimensions is here contrasted with the uniformity and ease of generalization of the Conservation Element and Solution Element (CE/SE) 1D scalar schemes to systems of equations and to multiple spatial dimensions. The assured compatibility with the simplest type of unstructured meshes, and the uniquely simple nonreflecting boundary conditions of the present method are also discussed. The present approach has yielded high-resolution shocks, rarefaction waves, acoustic waves, vortices, ZND detonation waves, and shock/acoustic waves/vortices interactions. Moreover, since no directional splitting is employed, numerical resolution of two-dimensional calculations is comparable to that of the one-dimensional calculations. Some sample applications displaying the strengths and broad applicability of the CE/SE method are reviewed.

Generalization of von Neumann analysis for a model of two discrete half-spaces: The acoustic case

USGS Publications Warehouse

Haney, M.M.

2007-01-01

Evaluating the performance of finite-difference algorithms typically uses a technique known as von Neumann analysis. For a given algorithm, application of the technique yields both a dispersion relation valid for the discrete time-space grid and a mathematical condition for stability. In practice, a major shortcoming of conventional von Neumann analysis is that it can be applied only to an idealized numerical model - that of an infinite, homogeneous whole space. Experience has shown that numerical instabilities often arise in finite-difference simulations of wave propagation at interfaces with strong material contrasts. These interface instabilities occur even though the conventional von Neumann stability criterion may be satisfied at each point of the numerical model. To address this issue, I generalize von Neumann analysis for a model of two half-spaces. I perform the analysis for the case of acoustic wave propagation using a standard staggered-grid finite-difference numerical scheme. By deriving expressions for the discrete reflection and transmission coefficients, I study under what conditions the discrete reflection and transmission coefficients become unbounded. I find that instabilities encountered in numerical modeling near interfaces with strong material contrasts are linked to these cases and develop a modified stability criterion that takes into account the resulting instabilities. I test and verify the stability criterion by executing a finite-difference algorithm under conditions predicted to be stable and unstable. ?? 2007 Society of Exploration Geophysicists.

Anisotropic spectra of acoustic type turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuznetsov, E.; P.N. Lebedev Physical Institute, 53 Leninsky Ave., 119991 Moscow; Krasnoselskikh, V.

2008-06-15

The problem of spectra for acoustic type of turbulence generated by shocks being randomly distributed in space is considered. It is shown that for turbulence with a weak anisotropy, such spectra have the same dependence in k-space as the Kadomtsev-Petviashvili spectrum: E(k){approx}k{sup -2}. However, the frequency spectrum has always the falling {approx}{omega}{sup -2}, independent of anisotropy. In the strong anisotropic case the energy distribution relative to wave vectors takes anisotropic dependence, forming in the large-k region spectra of the jet type.

Pressure Oscillations and Structural Vibrations in Space Shuttle RSRM and ETM-3 Motors

NASA Technical Reports Server (NTRS)

Mason, D. R.; Morstadt, R. A.; Cannon, S. M.; Gross, E. G.; Nielsen, D. B.

2004-01-01

The complex interactions between internal motor pressure oscillations resulting from vortex shedding, the motor's internal acoustic modes, and the motor's structural vibration modes were assessed for the Space Shuttle four-segment booster Reusable Solid Rocket Motor and for the five-segment engineering test motor ETM-3. Two approaches were applied 1) a predictive procedure based on numerically solving modal representations of a solid rocket motor s acoustic equations of motion and 2) a computational fluid dynamics two-dimensional axi-symmetric large eddy simulation at discrete motor burn times.

Analyzing panel acoustic contributions toward the sound field inside the passenger compartment of a full-size automobile.

PubMed

Wu, Sean F; Moondra, Manmohan; Beniwal, Ravi

2015-04-01

The Helmholtz equation least squares (HELS)-based nearfield acoustical holography (NAH) is utilized to analyze panel acoustic contributions toward the acoustic field inside the interior region of an automobile. Specifically, the acoustic power flows from individual panels are reconstructed, and relative contributions to sound pressure level and spectrum at any point of interest are calculated. Results demonstrate that by correlating the acoustic power flows from individual panels to the field acoustic pressure, one can correctly locate the panel allowing the most acoustic energy transmission into the vehicle interior. The panel on which the surface acoustic pressure amplitude is the highest should not be used as indicative of the panel responsible for the sound field in the vehicle passenger compartment. Another significant advantage of this HELS-based NAH is that measurements of the input data only need to be taken once by using a conformal array of microphones in the near field, and ranking of panel acoustic contributions to any field point can be readily performed. The transfer functions between individual panels of any vibrating structure to the acoustic pressure anywhere in space are calculated not measured, thus significantly reducing the time and effort involved in panel acoustic contributions analyses.

Estimating Noise Levels In An Enclosed Space

NASA Technical Reports Server (NTRS)

Azzi, Elias

1995-01-01

GEGS Acoustic Analysis Program (GAAP) developed to compute composite profile of noise in Spacelab module on basis of data on noise produced by equipment, data on locations of equipment, and equipment-operating schedules. Impetus for development of GAAP provided by noise that generated in Spacelab Module during SLS-1 mission because of concurrent operation of many pieces of experimental and subsystem equipment. Although originally intended specifically to help compute noise in Spacelab, also applicable to any region with multiple sources of noise. Written in FORTRAN 77.

High temperature polyimide foams for shuttle upper surface thermal insulation

NASA Technical Reports Server (NTRS)

Ball, G. L., III; Leffingwell, J. W.; Salyer, I. O.; Werkmeister, D. W.

1974-01-01

Polyimide foams developed by Monsanto Company were examined for use as upper surface space shuttle thermal insulation. It was found that postcured polyimide foams having a density of 64 kg/cu m (4 lb/cu ft) had acceptable physical properties up to and exceeding 700 K (800 F). Physical tests included cyclic heating and cooling in vacuum, weight and dimensional stability, mechanical strength and impact resistance, acoustic loading and thermal conductivity. Molding and newly developed postcuring procedures were defined.

The ecological and evolutionary consequences of noise-induced acoustic habitat loss

NASA Astrophysics Data System (ADS)

Tennessen, Jennifer Beissinger

Anthropogenic threats are facilitating rapid environmental change and exerting novel pressures on the integrity of ecological patterns and processes. Currently, habitat loss is the leading factor contributing to global biodiversity loss. Noise created by human activities is nearly ubiquitous in terrestrial and marine systems, and causes acoustic habitat loss by interfering with species' abilities to freely send and receive critical acoustic biological information. My dissertation investigates how novel sounds from human activities affect ecological and evolutionary processes in space and time in marine and terrestrial systems, and how species may cope with this emerging novel pressure. Using species from both marine and terrestrial systems, I present results from a theoretical investigation, and four acoustic playback experiments combining laboratory studies and field trials, that reveal a range of eco-evolutionary consequences of noiseinduced acoustic habitat loss. First, I use sound propagation modeling to assess how marine shipping noise reduces communication space between mother-calf pairs of North Atlantic right whales (Eubalaena glacialis ), an important unit of an endangered species. I show that shipping noise poses significant challenges for mother-calf pairs, but that vocal compensation strategies can substantially improve communication space. Next, in a series of acoustic playback experiments I show that road traffic noise impairs breeding migration behavior and physiology of wood frogs (Lithobates sylvaticus ). This work reveals the first evidence that traffic noise elicits a physiological stress response and suppresses production of antimicrobial peptides (a component of the innate immune response) in anurans. Further, wood frogs from populations with a history of inhabiting noisy sites mounted reduced physiological stress responses to continuous traffic noise exposure. This research using wood frogs suggests that chronic traffic noise exposure has negative physiological consequences, and that populations have adapted over short timescales to minimize the detrimental impacts of this novel pressure. Finally, I present results from a field acoustic playback experiment that show that noise from the invasive Cuban treefrog (Osteopilus septentrionalis ) differentially affects the vocal behavior of native anurans, with those with more similar calls being disproportionally more affected. Green treefrogs (Hyla cinerea) shortened their calls, called louder, and maintained call spacing (e.g. continued actively calling) during noise stimuli whereas pine woods treefrogs (H. femoralis) did not modify vocal behavior in response to any noise stimuli. Collectively, the results of these investigations (1) provide insight into the extent of noise-induced acoustic habitat loss in space and time, (2) reveal fitness-relevant individual- and population-level consequences of this form of habitat loss, and (3) show resiliency within ecological systems through the individual- and population-level responses to this novel pressure over short time-scales. These findings advance the field by illustrating how the spatiotemporal extent of anthropogenic noise impacts important ecological processes, and by demonstrating the resiliency of some species in responding rapidly to novel pressures.

Methods utilized in evaluating the profitability of commercial space processing

NASA Technical Reports Server (NTRS)

Bloom, H. L.; Schmitt, P. T.

1976-01-01

Profitability analysis is applied to commercial space processing on the basis of business concept definition and assessment and the relationship between ground and space functions. Throughput analysis is demonstrated by analysis of the space manufacturing of surface acoustic wave devices. The paper describes a financial analysis model for space processing and provides key profitability measures for space processed isoenzymes.

Automation of Space Inventory Management

NASA Technical Reports Server (NTRS)

Fink, Patrick W.; Ngo, Phong; Wagner, Raymond; Barton, Richard; Gifford, Kevin

2009-01-01

This viewgraph presentation describes the utilization of automated space-based inventory management through handheld RFID readers and BioNet Middleware. The contents include: 1) Space-Based INventory Management; 2) Real-Time RFID Location and Tracking; 3) Surface Acoustic Wave (SAW) RFID; and 4) BioNet Middleware.

Sports & Noise: How Much Is Too Much?

ERIC Educational Resources Information Center

Penman, Kenneth A.; And Others

1977-01-01

Acoustical studies in seven different spaces in the four buildings of the WSU athletic complex measured noise levels and sound reverberation rates. The spaces measured were far noisier and more reverberant than quality educational spaces should be. Suggestions are made for improvement. (Author/MLF)

Laser-speckle-visibility acoustic spectroscopy in soft turbid media.

PubMed

Wintzenrieth, Frédéric; Cohen-Addad, Sylvie; Le Merrer, Marie; Höhler, Reinhard

2014-01-01

We image the evolution in space and time of an acoustic wave propagating along the surface of turbid soft matter by shining coherent light on the sample. The wave locally modulates the speckle interference pattern of the backscattered light, which is recorded using a camera. We show both experimentally and theoretically how the temporal and spatial correlations in this pattern can be analyzed to obtain the acoustic wavelength and attenuation length. The technique is validated using shear waves propagating in aqueous foam. It may be applied to other kinds of acoustic waves in different forms of turbid soft matter such as biological tissues, pastes, or concentrated emulsions.

Laser-speckle-visibility acoustic spectroscopy in soft turbid media

NASA Astrophysics Data System (ADS)

Wintzenrieth, Frédéric; Cohen-Addad, Sylvie; Le Merrer, Marie; Höhler, Reinhard

2014-01-01

We image the evolution in space and time of an acoustic wave propagating along the surface of turbid soft matter by shining coherent light on the sample. The wave locally modulates the speckle interference pattern of the backscattered light, which is recorded using a camera. We show both experimentally and theoretically how the temporal and spatial correlations in this pattern can be analyzed to obtain the acoustic wavelength and attenuation length. The technique is validated using shear waves propagating in aqueous foam. It may be applied to other kinds of acoustic waves in different forms of turbid soft matter such as biological tissues, pastes, or concentrated emulsions.

Capacitive acoustic wave detector and method of using same

NASA Technical Reports Server (NTRS)

Yost, William T. (Inventor)

1994-01-01

A capacitor having two substantially parallel conductive faces is acoustically coupled to a conductive sample end such that the sample face is one end of the capacitor. A non-contacting dielectric may serve as a spacer between the two conductive plates. The formed capacitor is connected to an LC oscillator circuit such as a Hartley oscillator circuit producing an output frequency which is a function of the capacitor spacing. This capacitance oscillates as the sample end coating is oscillated by an acoustic wave generated in the sample by a transmitting transducer. The electrical output can serve as an absolute indicator of acoustic wave displacement.

Frequency-Based Spatial Correlation Assessments of the Ares I Subscale Acoustic Model Test Firings

NASA Technical Reports Server (NTRS)

Kenny, R. Jeremy; Houston, J.

2012-01-01

The Marshall Space Flight Center has performed a series of test firings to simulate and understand the acoustic environments generated for the Ares I liftoff profiles. Part of the instrumentation package had special sensor groups to assess the acoustic field spatial correlation features for the various test configurations. The spatial correlation characteristics were evaluated for all of the test firings, inclusive of understanding the diffuse to propagating wave amplitude ratios, the acoustic wave decays, and the incident angle of propagating waves across the sensor groups. These parameters were evaluated across the measured frequency spectra and the associated uncertainties for each parameter were estimated.

1KW Power Transmission Using Wireless Acoustic-Electric Feed-Through (WAEF)

NASA Technical Reports Server (NTRS)

Sherrit, S.; Bao, X.; Badescu, M.; Aldrich, J.; Bar-Cohen, Y.; Biederman, W.

2008-01-01

A variety of space applications require the delivery of power into sealed structures. Since the structural integrity can be degraded by holes for cabling we present an alternative method of delivering power and information using stress waves to the internal space of a sealed structure. One particular application of this technology is in sample return missions where it is critical to preserve the sample integrity and to prevent earth contamination. Therefore, the container has to be hermetically sealed and the integrity of the seal must be monitored in order to insure to a high degree of reliability the integrity of the sample return vessel. In this study we investigated the use of piezoelectric acoustic-electric power feed-through devices to transfer electric power wirelessly through a solid wall by using elastic or acoustic waves. The technology is applicable to a range of space and terrestrial applications where power is required by electronic equipment inside sealed containers, vacuum or pressure vessels, etc., where holes in the wall are prohibitive or may result in significant structural performance degradation or unnecessarily complex designs. To meet requirements of higher power applications, the feasibility to transfer kilowatts level power was investigated. Pre-stressed longitudinal piezoelectric feed-through devices were analyzed by finite element models and an equivalent circuit model was developed to predict the power transfer characteristics to different electric loads. Based on the results of the analysis a prototype device was designed, fabricated and a demonstration of the transmission of electric power up to 1.068-kW was successfully conducted. Efficiencies in the 80-90% range were also demonstrated and methods to increase the efficiency further are currently being considered.

Saturn systems holddown acoustic efficiency and normalized acoustic power spectrum.

NASA Technical Reports Server (NTRS)

Gilbert, D. W.

1972-01-01

Saturn systems field acoustic data are used to derive mid- and far-field prediction parameters for rocket engine noise. The data were obtained during Saturn vehicle launches at the Kennedy Space Center. The data base is a sorted set of acoustic data measured during the period 1961 through 1971 for Saturn system launches SA-1 through AS-509. The model assumes hemispherical radiation from a simple source located at the intersection of the longitudinal axis of each booster and the engine exit plane. The model parameters are evaluated only during vehicle holddown. The acoustic normalized power spectrum and efficiency for each system are isolated as a composite from the data using linear numerical methods. The specific definitions of each allows separation. The resulting power spectra are nondimensionalized as a function of rocket engine parameters. The nondimensional Saturn system acoustic spectrum and efficiencies are compared as a function of Strouhal number with power spectra from other systems.

Liquid-assisted tunable metasurface for simultaneous manipulation of surface elastic and acoustic waves

NASA Astrophysics Data System (ADS)

Yuan, Si-Min; Ma, Tian-Xue; Chen, A.-Li; Wang, Yue-Sheng

2018-03-01

A tunable and multi-functional one-dimensional metasurface, which is formed by engraving periodic semi-ellipse grooves on the surface of an aluminum half-space, is proposed in this paper. One characteristic of the metasurface is the manipulation of multi-physical fields, i.e. it could be utilized to manipulate surface elastic and acoustic waves simultaneously. The dispersion curves of the elastic and acoustic waves can be effectively tuned by adding liquids into the grooves. Based on the tunability different applications can be realized by adding different volumes of different liquids into the grooves. As an example, simultaneous rainbow trapping of the surface elastic and acoustic waves is demonstrated in the metasurface. Moreover, a resonant cavity where the elastic and acoustic waves are highly confined is reported. The proposed metasurface paves the way to the design of multi-functional devices for simultaneous control of elastic and acoustic waves.

Prediction of Acoustic Loads Generated by Propulsion Systems

NASA Technical Reports Server (NTRS)

Perez, Linamaria; Allgood, Daniel C.

2011-01-01

NASA Stennis Space Center is one of the nation's premier facilities for conducting large-scale rocket engine testing. As liquid rocket engines vary in size, so do the acoustic loads that they produce. When these acoustic loads reach very high levels they may cause damages both to humans and to actual structures surrounding the testing area. To prevent these damages, prediction tools are used to estimate the spectral content and levels of the acoustics being generated by the rocket engine plumes and model their propagation through the surrounding atmosphere. Prior to the current work, two different acoustic prediction tools were being implemented at Stennis Space Center, each having their own advantages and disadvantages depending on the application. Therefore, a new prediction tool was created, using NASA SP-8072 handbook as a guide, which would replicate the same prediction methods as the previous codes, but eliminate any of the drawbacks the individual codes had. Aside from replicating the previous modeling capability in a single framework, additional modeling functions were added thereby expanding the current modeling capability. To verify that the new code could reproduce the same predictions as the previous codes, two verification test cases were defined. These verification test cases also served as validation cases as the predicted results were compared to actual test data.

Acoustic Modal Patterns and Striations (AMPS) experiment G-325, Norfolk Public Schools

NASA Technical Reports Server (NTRS)

Young, Joy W.

1995-01-01

This paper will describe how high school students with the guidance of volunteer mentors were able to successfully complete an acoustics space experiment. Some of the NORSTAR program strategies used to effectively accomplish this goal will be discussed. The experiment and present status of results will be explained.

Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mbuli, L. N.; Maharaj, S. K.; Department of Physics, University of the Western Cape

We examine the characteristics of fast electron-acoustic solitons in a four-component unmagnetised plasma model consisting of cool, warm, and hot electrons, and cool ions. We retain the inertia and pressure for all the plasma species by assuming adiabatic fluid behaviour for all the species. By using the Sagdeev pseudo-potential technique, the allowable Mach number ranges for fast electron-acoustic solitary waves are explored and discussed. It is found that the cool and warm electron number densities determine the polarity switch of the fast electron-acoustic solitons which are limited by either the occurrence of fast electron-acoustic double layers or warm and hotmore » electron number density becoming unreal. For the first time in the study of solitons, we report on the coexistence of fast electron-acoustic solitons, in addition to the regular fast electron-acoustic solitons and double layers in our multi-species plasma model. Our results are applied to the generation of broadband electrostatic noise in the dayside auroral region.« less

Bioeffects due to acoustic droplet vaporization

NASA Astrophysics Data System (ADS)

Bull, Joseph

2015-11-01

Encapsulated micro- and nano-droplets can be vaporized via ultrasound, a process termed acoustic droplet vaporization. Our interest is primarily motivated by a developmental gas embolotherapy technique for cancer treatment. In this methodology, infarction of tumors is induced by selectively formed vascular gas bubbles that arise from the acoustic vaporization of vascular microdroplets. Additionally, the microdroplets may be used as vehicles for localized drug delivery, with or without flow occlusion. In this talk, we examine the dynamics of acoustic droplet vaporization through experiments and theoretical/computational fluid mechanics models, and investigate the bioeffects of acoustic droplet vaporization on endothelial cells and in vivo. Early timescale vaporization events, including phase change, are directly visualized using ultra-high speed imaging, and the influence of acoustic parameters on droplet/bubble dynamics is discussed. Acoustic and fluid mechanics parameters affecting the severity of endothelial cell bioeffects are explored. These findings suggest parameter spaces for which bioeffects may be reduced or enhanced, depending on the objective of the therapy. This work was supported by NIH grant R01EB006476.

Application of the wavenumber jump condition to the normal and oblique interaction of a plane acoustic wave and a plane shock

NASA Technical Reports Server (NTRS)

Kleinstein, G. G.; Gunzburger, M. D.

1977-01-01

The kinematics of normal and oblique interactions between a plane acoustic wave and a plane shock wave are investigated separately using an approach whereby the shock is considered as a sharp discontinuity surface separating two half-spaces, so that the dispersion relation on either side of the shock and the wavenumber jump condition across a discontinuity surface completely specify the kinematics of the problem in the whole space independently of the acoustic-field dynamics. The normal interaction is analyzed for a stationary shock, and the spectral change of the incident wave is investigated. The normal interaction is then examined for the case of a shock wave traveling into an ambient region where an acoustic disturbance is propagating in the opposite direction. Detailed attention is given to the consequences of the existence of a critical shock speed above which the frequency of the transmitted wave becomes negative. Finally, the oblique interaction with a fixed shock is considered, and the existence and nature of the transmitted wave is investigated, particularly as a function of the angle of incidence.

5 Percent Ares I Scale Model Acoustic Test: Overpressure Characterization and Analysis

NASA Technical Reports Server (NTRS)

Alvord, David; Casiano, Matthew; McDaniels, Dave

2011-01-01

During the ignition of a ducted solid rocket motor (SRM), rapid expansion of injected hot gases from the motor into a confined volume causes the development of a steep fronted wave. This low frequency transient wave propagates outward from the exhaust duct, impinging the vehicle and ground structures. An unsuppressed overpressure wave can potentially cause modal excitation in the structures and vehicle, subsequently leading to damage. This presentation details the ignition transient f indings from the 5% Ares I Scale Model Acoustic Test (ASMAT). The primary events of the ignition transient environment induced by the SRM are the ignition overpressure (IOP), duct overpressure (DOP), and source overpressure (SOP). The resulting observations include successful knockdown of the IOP environment through use of a Space Shuttle derived IOP suppression system, a potential load applied to the vehicle stemming from instantaneous asymmetrical IOP and DOP wave impingement, and launch complex geometric influences on the environment. The results are scaled to a full-scale Ares I equivalent and compared with heritage data including Ares I-X and both suppressed and unsuppressed Space Shuttle IOP environments.

Modeling nonlinear ultrasound propagation in heterogeneous media with power law absorption using a k-space pseudospectral method.

PubMed

Treeby, Bradley E; Jaros, Jiri; Rendell, Alistair P; Cox, B T

2012-06-01

The simulation of nonlinear ultrasound propagation through tissue realistic media has a wide range of practical applications. However, this is a computationally difficult problem due to the large size of the computational domain compared to the acoustic wavelength. Here, the k-space pseudospectral method is used to reduce the number of grid points required per wavelength for accurate simulations. The model is based on coupled first-order acoustic equations valid for nonlinear wave propagation in heterogeneous media with power law absorption. These are derived from the equations of fluid mechanics and include a pressure-density relation that incorporates the effects of nonlinearity, power law absorption, and medium heterogeneities. The additional terms accounting for convective nonlinearity and power law absorption are expressed as spatial gradients making them efficient to numerically encode. The governing equations are then discretized using a k-space pseudospectral technique in which the spatial gradients are computed using the Fourier-collocation method. This increases the accuracy of the gradient calculation and thus relaxes the requirement for dense computational grids compared to conventional finite difference methods. The accuracy and utility of the developed model is demonstrated via several numerical experiments, including the 3D simulation of the beam pattern from a clinical ultrasound probe.

Combustion Dynamics and Stability Modeling of a Liquid Oxygen/RP-2 Oxygen-Rich Staged Combustion Preburner and Thrust Chamber Assembly with Gas-Centered Swirl Coaxial Injector Elements

NASA Technical Reports Server (NTRS)

Casiano, M. J.; Kenny, R. J.; Protz, C. S.; Garcia, C. P.; Simpson, S. P.; Elmore, J. L.; Fischbach, S. R.; Giacomoni, C. B.; Hulka, J. R.

2016-01-01

The Combustion Stability Tool Development (CSTD) project, funded by the Air Force Space and Missile Systems Center, began in March 2015 supporting a renewed interest in the development of a liquid oxygen/hydrocarbon, oxygen-rich combustion engine. The project encompasses the design, assembly, and hot-fire testing of the NASA Marshall Space Flight Center 40-klbf Integrated Test Rig (MITR). The test rig models a staged-combustion configuration by combining an oxygen-rich preburner (ORPB), to generate hot gas, with a thrust chamber assembly (TCA) using gas-centered swirl coaxial injector elements. There are five separately designed interchangeable injectors in the TCA that each contain 19- or 27- injector elements. A companion paper in this JANNAF conference describes the design characteristics, rationale, and fabrication issues for all the injectors. The data acquired from a heavily instrumented rig encompasses several injectors, several operating points, and stability bomb tests. Another companion paper in this JANNAF conference describes this test program in detail. In this paper, dynamic data from the hot-fire testing is characterized and used to identify the responses in the ORPB and TCA. A brief review of damping metrics are discussed and applied as a measure of stability margin for damped acoustic modes. Chug and longitudinal combustion stability models and predictions are described which includes new dynamic models for compressible flow through an orifice and a modification to incorporate a third feed line for inclusion of the fuel-film coolant. Flow-acoustics finite element modeling is used to investigate the anticipated TCA acoustics, the effects of injector element length on stability margin, and the potential use of an ORPB orifice trip ring for improving longitudinal stability margin.

A theoretical prediction of the acoustic pressure generated by turbulence-flame front interactions

NASA Technical Reports Server (NTRS)

Huff, R. G.

1984-01-01

The equations of momentum annd continuity are combined and linearized yielding the one dimensional nonhomogeneous acoustic wave equation. Three terms in the non-homogeneous equation act as acoustic sources and are taken to be forcing functions acting on the homogeneous wave equation. The three source terms are: fluctuating entropy, turbulence gradients, and turbulence-flame interactions. Each source term is discussed. The turbulence-flame interaction source is used as the basis for computing the source acoustic pressure from the Fourier transformed wave equation. Pressure fluctuations created in turbopump gas generators and turbines may act as a forcing function for turbine and propellant tube vibrations in Earth to orbit space propulsion systems and could reduce their life expectancy. A preliminary assessment of the acoustic pressure fluctuations in such systems is presented.

A theoretical prediction of the acoustic pressure generated by turbulence-flame front interactions

NASA Technical Reports Server (NTRS)

Huff, R. G.

1984-01-01

The equations of momentum and continuity are combined and linearized yielding the one dimensional nonhomogeneous acoustic wave equation. Three terms in the non-homogeneous equation act as acoustic sources and are taken to be forcing functions acting on the homogeneous wave equation. The three source terms are: fluctuating entropy, turbulence gradients, and turbulence-flame interactions. Each source term is discussed. The turbulence-flame interaction source is used as the basis for computing the source acoustic pressure from the Fourier transformed wave equation. Pressure fluctuations created in turbopump gas generators and turbines may act as a forcing function for turbine and propellant tube vibrations in earth to orbit space propulsion systems and could reduce their life expectancy. A preliminary assessment of the acoustic pressure fluctuations in such systems is presented.

Method and apparatus for separating mixtures of gases using an acoustic wave

DOEpatents

Geller, Drew A.; Swift, Gregory W.; Backhaus, Scott N.

2004-05-11

A thermoacoustic device separates a mixture of gases. An elongated duct is provided with first and second ends and has a length that is greater than the wavelength of sound in the mixture of gases at a selected frequency, and a diameter that is greater than a thermal penetration depth in the mixture of gases. A first acoustic source is located at the first end of the duct to generate acoustic power at the selected frequency. A plurality of side branch acoustic sources are spaced along the length of the duct and are configured to introduce acoustic power into the mixture of gases so that a first gas is concentrated at the first end of the duct and a second gas is concentrated at the second end of the duct.

Acoustic imaging system

DOEpatents

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.

Subjective scaling of spatial room acoustic parameters influenced by visual environmental cues

PubMed Central

Valente, Daniel L.; Braasch, Jonas

2010-01-01

Although there have been numerous studies investigating subjective spatial impression in rooms, only a few of those studies have addressed the influence of visual cues on the judgment of auditory measures. In the psychophysical study presented here, video footage of five solo music∕speech performers was shown for four different listening positions within a general-purpose space. The videos were presented in addition to the acoustic signals, which were auralized using binaural room impulse responses (BRIR) that were recorded in the same general-purpose space. The participants were asked to adjust the direct-to-reverberant energy ratio (D∕R ratio) of the BRIR according to their expectation considering the visual cues. They were also directed to rate the apparent source width (ASW) and listener envelopment (LEV) for each condition. Visual cues generated by changing the sound-source position in the multi-purpose space, as well as the makeup of the sound stimuli affected the judgment of spatial impression. Participants also scaled the direct-to-reverberant energy ratio with greater direct sound energy than was measured in the acoustical environment. PMID:20968367

Investigation of Twin Jet Aeroacoustic Properties in the Presence of a Hybrid Wing Body Shield

NASA Technical Reports Server (NTRS)

Doty, Michael J.

2012-01-01

In preparation for upcoming wind tunnel acoustic experiments of a Hybrid Wing Body (HWB) vehicle with two jet engine simulator units, a series of twin jet aeroacoustic investigations were conducted leading to increased understanding and risk mitigation. A previously existing twin jet nozzle system and a fabricated HWB aft deck fuselage are combined for a 1.9% model scale study of jet nozzle spacing and jet cant angle effects, elevon deflection into the jet plume, and acoustic shielding by the fuselage body. Linear and phased array microphone measurements are made, and data processing includes the use of DAMAS (Deconvolution Approach for the Mapping of Acoustic Sources). Closely-spaced twin jets with a 5 inward cant angle exhibit reduced noise levels compared to their parallel flow counterparts at similar and larger nozzle spacings. A 40 elevon deflection into the twin jet plume, which is required for HWB ground rotation, can significantly increase upstream noise levels (more than 5 dB OASPL) with only minimal increases in the downstream direction. Lastly, DAMAS processing can successfully measure the noise source distribution of multiple shielded jet sources.

On the generation of double layers from ion- and electron-acoustic instabilities

NASA Astrophysics Data System (ADS)

Fu, Xiangrong; Cowee, Misa M.; Gary, S. Peter; Winske, Dan

2016-03-01

A plasma double layer (DL) is a nonlinear electrostatic structure that carries a uni-polar electric field parallel to the background magnetic field due to local charge separation. Past studies showed that DLs observed in space plasmas are mostly associated with the ion acoustic instability. Recent Van Allen Probes observations of parallel electric field structures traveling much faster than the ion acoustic speed have motivated a computational study to test the hypothesis that a new type of DLs—electron acoustic DLs—generated from the electron acoustic instability are responsible for these electric fields. Nonlinear particle-in-cell simulations yield negative results, i.e., the hypothetical electron acoustic DLs cannot be formed in a way similar to ion acoustic DLs. Linear theory analysis and the simulations show that the frequencies of electron acoustic waves are too high for ions to respond and maintain charge separation required by DLs. However, our results do show that local density perturbations in a two-electron-component plasma can result in unipolar-like electric field structures that propagate at the electron thermal speed, suggesting another potential explanation for the observations.

RECENT DEVELOPMENTS IN HYDROLOGIC INSTRUMENTATION.

USGS Publications Warehouse

Latkovich, Vito J.

1985-01-01

The availability of space-age materials and implementation of state-of-the-art electronics is making possible the recent developments of hydrologic instrumentation. Material developments include: Synthetic-fiber sounding and tag lines; fiberglass wading rod; polymer (plastic) sheaves, pulleys and sampler components; and polymer (plastic) bucket wheels for current meters. These materials are very cost effective and efficient. Electromechanical and electronic developments and applications include: adaptable data acquisition system; downhole sampler for hazardous substances; current-meter digitizer; hydraulic power/drive system for discharge measurements and water-quality sampling; non-contact water-level sensors; minimum data recorder; acoustic velocity meters, and automated current meter discharge-measurement system.

Articulatory changes in muscle tension dysphonia: evidence of vowel space expansion following manual circumlaryngeal therapy.

PubMed

Roy, Nelson; Nissen, Shawn L; Dromey, Christopher; Sapir, Shimon

2009-01-01

In a preliminary study, we documented significant changes in formant transitions associated with successful manual circumlaryngeal treatment (MCT) of muscle tension dysphonia (MTD), suggesting improvement in speech articulation. The present study explores further the effects of MTD on vowel articulation by means of additional vowel acoustic measures. Pre- and post-treatment audio recordings of 111 women with MTD were analyzed acoustically using two measures: vowel space area (VSA) and vowel articulation index (VAI), constructed using the first (F1) and second (F2) formants of 4 point vowels/ a, i, ae, u/, extracted from eight words within a standard reading passage. Pairwise t-tests revealed significant increases in both VSA and VAI, confirming that successful treatment of MTD is associated with vowel space expansion. Although MTD is considered a voice disorder, its treatment with MCT appears to positively affect vocal tract dynamics. While the precise mechanism underlying vowel space expansion remains unknown, improvements may be related to lowering of the larynx, expanding oropharyngeal space, and improving articulatory movements. The reader will be able to: (1) describe possible articulatory changes associated with successful treatment of muscle tension dysphonia; (2) describe two acoustic methods to assess vowel centralization and decentralization, and; (3) understand the basis for viewing muscle tension dysphonia as a disorder not solely confined to the larynx.

ATK Launch Vehicle (ALV-X1) Liftoff Acoustic Environments: Prediction vs. Measurement

NASA Technical Reports Server (NTRS)

Houston, Janice; Counter, Douglas; Kenny, Jeremy; Murphy, John

2009-01-01

The ATK Launch Vehicle (ALV-X1) provided an opportunity to measure liftoff acoustic noise data. NASA Marshall Space Flight Center (MSFC) engineers were interested in the ALV-X1 launch because the First Stage motor and launch pad conditions, including a relativity short deflector ducting, provide a potential analogue to future Ares I launches. This paper presents the measured liftoff acoustics on the vehicle and tower. Those measured results are compared to predictions based upon the method described in NASA SP-8072 "Acoustic Loads Generated by the Propulsion System" and the Vehicle Acoustic Environment Prediction Program (VAEPP) which was developed by MSFC acoustics engineers. One-third octave band sound pressure levels will be presented. This data is useful for the ALV-X1 in validating the pre-launch environments and loads predictions. Additionally, the ALV-X1 liftoff data can be scaled to define liftoff environments for the NASA Constellation program Ares vehicles. Vehicle liftoff noise is caused by the supersonic jet flow interaction with surrounding atmosphere or more simply, jet noise. As the vehicle's First Stage motor is ignited, an acoustic noise field is generated by the exhaust. This noise field persists due to the supersonic jet noise and reflections from the launch pad and tower, then changes as the vehicle begins to liftoff from the launch pad. Depending on launch pad and adjacent tower configurations, the liftoff noise is generally very high near the nozzle exit and decreases rapidly away from the nozzle. The liftoff acoustic time range of interest is typically 0 to 20 seconds after ignition. The exhaust plume thermo-fluid mechanics generates sound at approx.10 Hz to 20 kHz. Liftoff acoustic noise is usually the most severe dynamic environment for a launch vehicle or payload in the mid to high frequency range (approx.50 to 2000 Hz). This noise environment can induce high-level vibrations along the external surfaces of the vehicle and surrounding launch facility structures. The acoustic pressure fluctuations will induce severe vibrations in relatively large lightweight structures. Consequently, there is the potential for failure of the structure or attached electrical components. Due to these potential failures, the liftoff acoustic noise is one of the noise source inputs used to determine the vibro-acoustic qualification environment for a launch vehicle and its components.

Vessel noise cuts down communication space for vocalizing fish and marine mammals.

PubMed

Putland, Rosalyn L; Merchant, Nathan D; Farcas, Adrian; Radford, Craig A

2018-04-01

Anthropogenic noise across the world's oceans threatens the ability of vocalizing marine species to communicate. Some species vocalize at key life stages or whilst foraging, and disruption to the acoustic habitat at these times could lead to adverse consequences at the population level. To investigate the risk of these impacts, we investigated the effect of vessel noise on the communication space of the Bryde's whale Balaenoptera edeni, an endangered species which vocalizes at low frequencies, and bigeye Pempheris adspersa, a nocturnal fish species which uses contact calls to maintain group cohesion while foraging. By combining long-term acoustic monitoring data with AIS vessel-tracking data and acoustic propagation modelling, the impact of vessel noise on their communication space was determined. Routine vessel passages cut down communication space by up to 61.5% for bigeyes and 87.4% for Bryde's whales. This influence of vessel noise on communication space exceeded natural variability for between 3.9 and 18.9% of the monitoring period. Additionally, during the closest point of approach of a large commercial vessel, <10 km from the listening station, the communication space of both species was reduced by a maximum of 99% compared to the ambient soundscape. These results suggest that vessel noise reduces communication space beyond the evolutionary context of these species and may have chronic effects on these populations. To combat this risk, we propose the application or extension of ship speed restrictions in ecologically significant areas, since our results indicate a reduction in sound source levels for vessels transiting at lower speeds. © 2017 John Wiley & Sons Ltd.

NDE of the space shuttle orbiter thermal protection system: Phase 2 final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tow, D.M.; Barna, B.A.; Rodriguez, J.G.

1989-03-01

Research continued on the development of a nondestructive evaluation technique for inspecting bonds on the space shuttle orbiter thermal protection system tiles. The approach taken uses a noncontacting laser sensor to measure the vibrational response of bonded tiles to acoustical excitation. Laboratory work concentrated on investigating the dynamic response of ''acreage'' tiles, i.e., tiles covering the underside of the orbiter, all approximately square. A number of promising unbond signatures have been identified in the time and frequency domain response. Field tests were conducted to study environmental effects on the techniques being developed. The ambient motion of the orbiter was foundmore » to be larger than expected, necessitating modifications to current techniques. 2 refs., 21 figs., 1 tab.« less

Two Heat-Transfer Improvements for Gas Liquefiers

NASA Technical Reports Server (NTRS)

Martin, Jerry L.

2005-01-01

Two improvements in heat-transfer design have been investigated with a view toward increasing the efficiency of refrigerators used to liquefy gases. The improvements could contribute to the development of relatively inexpensive, portable oxygen liquefiers for medical use. A description of the heat-transfer problem in a pulse-tube refrigerator is prerequisite to a meaningful description of the first improvement. In a pulse-tube refrigerator in particular, one of in-line configuration heat must be rejected from two locations: an aftercooler (where most of the heat is rejected) and a warm heat exchanger (where a small fraction of the total input power must be rejected as heat). Rejection of heat from the warm heat exchanger can be problematic because this heat exchanger is usually inside a vacuum vessel. When an acoustic-inertance tube is used to provide a phase shift needed in the pulse-tube cooling cycle, another problem arises: Inasmuch as the acoustic power in the acoustic-inertance tube is dissipated over the entire length of the tube, the gas in the tube must be warmer than the warm heat exchanger in order to reject heat at the warm heat exchanger. This is disadvantageous because the increase in viscosity with temperature causes an undesired increase in dissipation of acoustic energy and an undesired decrease in the achievable phase shift. Consequently, the overall performance of the pulse-tube refrigerator decreases with increasing temperature in the acoustic-inertance tube. In the first improvement, the acoustic-inertance tube is made to serve as the warm heat exchanger and to operate in an approximately isothermal condition at a lower temperature, thereby increasing the achievable phase shift and the overall performance of the refrigerator. This is accomplished by placing the acoustic-inertance tube inside another tube and pumping a cooling fluid (e.g., water) in the annular space between the tubes. Another benefit of this improvement is added flexibility of design to locate the warm heat-rejection components outside the vacuum vessel. The second improvement is the development of a compact radial-flow condenser characterized by a very high heat transfer coefficient and a small pressure drop.

Computational Analyses in Support of Sub-scale Diffuser Testing for the A-3 Facility. Part 3; Aero-Acoustic Analyses and Experimental Validation

NASA Technical Reports Server (NTRS)

Allgood, Daniel C.; Graham, Jason S.; McVay, Greg P.; Langford, Lester L.

2008-01-01

A unique assessment of acoustic similarity scaling laws and acoustic analogy methodologies in predicting the far-field acoustic signature from a sub-scale altitude rocket test facility at the NASA Stennis Space Center was performed. A directional, point-source similarity analysis was implemented for predicting the acoustic far-field. In this approach, experimental acoustic data obtained from "similar" rocket engine tests were appropriately scaled using key geometric and dynamic parameters. The accuracy of this engineering-level method is discussed by comparing the predictions with acoustic far-field measurements obtained. In addition, a CFD solver was coupled with a Lilley's acoustic analogy formulation to determine the improvement of using a physics-based methodology over an experimental correlation approach. In the current work, steady-state Reynolds-averaged Navier-Stokes calculations were used to model the internal flow of the rocket engine and altitude diffuser. These internal flow simulations provided the necessary realistic input conditions for external plume simulations. The CFD plume simulations were then used to provide the spatial turbulent noise source distributions in the acoustic analogy calculations. Preliminary findings of these studies will be discussed.

A binaural Web-based tour of the acoustics of Troy Music Hall

NASA Astrophysics Data System (ADS)

Torres, Rendell R.; Cooney, James; Shimizu, Yasushi

2004-05-01

For classical music to become more widely enjoyed, it must sound exciting. We hypothesize that if people could hear examples of truly exciting acoustics, classical music would be perceived less as a rarefied delicacy and more as a viscerally engaging listening experience. The Troy Savings Bank Music Hall in Troy, New York, is a legendary 1200-seat concert hall famous for its acoustics. Such landmarks are commonly documented architecturally but with few attempts to document their acoustics in a way that it is listenable. Thus, the goal is to capture and sonically disseminate the hall's acoustics through a Web-based acoustical tour, where one can click on various seats to hear binaural auralizations of different instruments and see corresponding views of the stage. The hope is that these auralizations will not only sonically document the acoustics of the hall but also tantalize even geographically distant listeners with binaural samples of how exciting music can be in excellent acoustics. The fun and challenges of devising (let alone standardizing) such an auralization-based system of documentation will be discussed, and a demonstration given. This process can be applied to other historically and acoustically significant spaces. [Work supported by the National Endowment for the Arts.

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

NASA Astrophysics Data System (ADS)

Trujillo, Blaine; Zagrai, Andrei

2016-04-01

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

The Space-Time Conservative Schemes for Large-Scale, Time-Accurate Flow Simulations with Tetrahedral Meshes

NASA Technical Reports Server (NTRS)

Venkatachari, Balaji Shankar; Streett, Craig L.; Chang, Chau-Lyan; Friedlander, David J.; Wang, Xiao-Yen; Chang, Sin-Chung

2016-01-01

Despite decades of development of unstructured mesh methods, high-fidelity time-accurate simulations are still predominantly carried out on structured, or unstructured hexahedral meshes by using high-order finite-difference, weighted essentially non-oscillatory (WENO), or hybrid schemes formed by their combinations. In this work, the space-time conservation element solution element (CESE) method is used to simulate several flow problems including supersonic jet/shock interaction and its impact on launch vehicle acoustics, and direct numerical simulations of turbulent flows using tetrahedral meshes. This paper provides a status report for the continuing development of the space-time conservation element solution element (CESE) numerical and software framework under the Revolutionary Computational Aerosciences (RCA) project. Solution accuracy and large-scale parallel performance of the numerical framework is assessed with the goal of providing a viable paradigm for future high-fidelity flow physics simulations.

Active vibration and noise control of vibro-acoustic system by using PID controller

NASA Astrophysics Data System (ADS)

Li, Yunlong; Wang, Xiaojun; Huang, Ren; Qiu, Zhiping

2015-07-01

Active control simulation of the acoustic and vibration response of a vibro-acoustic cavity of an airplane based on a PID controller is presented. A full numerical vibro-acoustic model is developed by using an Eulerian model, which is a coupled model based on the finite element formulation. The reduced order model, which is used to design the closed-loop control system, is obtained by the combination of modal expansion and variable substitution. Some physical experiments are made to validate and update the full-order and the reduced-order numerical models. Optimization of the actuator placement is employed in order to get an effective closed-loop control system. For the controller design, an iterative method is used to determine the optimal parameters of the PID controller. The process is illustrated by the design of an active noise and vibration control system for a cavity structure. The numerical and experimental results show that a PID-based active control system can effectively suppress the noise inside the cavity using a sound pressure signal as the controller input. It is also possible to control the noise by suppressing the vibration of the structure using the structural displacement signal as the controller input. For an airplane cavity structure, considering the issue of space-saving, the latter is more suitable.

Acoustic Emission Analysis Applet (AEAA) Software

NASA Technical Reports Server (NTRS)

Nichols, Charles T.; Roth, Don J.

2013-01-01

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

Surface response of a viscoelastic medium to subsurface acoustic sources with application to medical diagnosis

NASA Astrophysics Data System (ADS)

Royston, Thomas J.; Yazicioglu, Yigit; Loth, Francis

2003-02-01

The response at the surface of an isotropic viscoelastic medium to buried fundamental acoustic sources is studied theoretically, computationally and experimentally. Finite and infinitesimal monopole and dipole sources within the low audible frequency range (40-400 Hz) are considered. Analytical and numerical integral solutions that account for compression, shear and surface wave response to the buried sources are formulated and compared with numerical finite element simulations and experimental studies on finite dimension phantom models. It is found that at low audible frequencies, compression and shear wave propagation from point sources can both be significant, with shear wave effects becoming less significant as frequency increases. Additionally, it is shown that simple closed-form analytical approximations based on an infinite medium model agree well with numerically obtained ``exact'' half-space solutions for the frequency range and material of interest in this study. The focus here is on developing a better understanding of how biological soft tissue affects the transmission of vibro-acoustic energy from biological acoustic sources below the skin surface, whose typical spectral content is in the low audible frequency range. Examples include sound radiated from pulmonary, gastro-intestinal and cardiovascular system functions, such as breath sounds, bowel sounds and vascular bruits, respectively.

Nighttime foraging by deep diving echolocating odontocetes off the Hawaiian islands of Kauai and Ni'ihau as determined by passive acoustic monitors.

PubMed

Au, Whitlow W L; Giorli, Giacomo; Chen, Jessica; Copeland, Adrienne; Lammers, Marc; Richlen, Michael; Jarvis, Susan; Morrissey, Ronald; Moretti, David; Klinck, Holger

2013-05-01

Remote autonomous ecological acoustic recorders (EARs) were deployed in deep waters at five locations around the island of Kauai and one in waters off Ni'ihau in the main Hawaiian island chain. The EARs were moored to the bottom at depths between 400 and 800 m. The data acquisition sampling rate was 80 kHz and acoustic signals were recorded for 30 s every 5 min to conserve battery power and disk space. The acoustic data were analyzed with the M3R (Marine Mammal Monitoring on Navy Ranges) software, an energy-ratio-mapping algorithm developed at Oregon State University and custom MATLAB programs. A variety of deep diving odontocetes, including pilot whales, Risso's dolphins, sperm whales, spinner and pan-tropical spotted dolphins, and beaked whales were detected at all sites. Foraging activity typically began to increase after dusk, peaked in the middle of the night and began to decrease toward dawn. Between 70% and 84% of biosonar clicks were detected at night. At present it is not clear why some of the known deep diving species, such as sperm whales and beaked whales, concentrate their foraging efforts at night.

A k-space method for acoustic propagation using coupled first-order equations in three dimensions.

PubMed

Tillett, Jason C; Daoud, Mohammad I; Lacefield, James C; Waag, Robert C

2009-09-01

A previously described two-dimensional k-space method for large-scale calculation of acoustic wave propagation in tissues is extended to three dimensions. The three-dimensional method contains all of the two-dimensional method features that allow accurate and stable calculation of propagation. These features are spectral calculation of spatial derivatives, temporal correction that produces exact propagation in a homogeneous medium, staggered spatial and temporal grids, and a perfectly matched boundary layer. Spectral evaluation of spatial derivatives is accomplished using a fast Fourier transform in three dimensions. This computational bottleneck requires all-to-all communication; execution time in a parallel implementation is therefore sensitive to node interconnect latency and bandwidth. Accuracy of the three-dimensional method is evaluated through comparisons with exact solutions for media having spherical inhomogeneities. Large-scale calculations in three dimensions were performed by distributing the nearly 50 variables per voxel that are used to implement the method over a cluster of computers. Two computer clusters used to evaluate method accuracy are compared. Comparisons of k-space calculations with exact methods including absorption highlight the need to model accurately the medium dispersion relationships, especially in large-scale media. Accurately modeled media allow the k-space method to calculate acoustic propagation in tissues over hundreds of wavelengths.

The effect of helicopter main rotor blade phasing and spacing on performance, blade loads, and acoustics

NASA Technical Reports Server (NTRS)

Gangwani, S. T.

1976-01-01

The performance, blade loads, and acoustic characteristics of a variable geometry rotor (VGR) system in forward flight and in a pullup maneuver were determined by the use of existing analytical programs. The investigation considered the independent effects of vertical separation of two three-bladed rotor systems as well as the effects of azimuthal spacing between the blades of the two rotors. The computations were done to determine the effects of these parameters on the performance, blade loads, and acoustic characteristics at two advance ratios in steady-state level flight and for two different g pullups at one advance ratio. To evaluate the potential benefits of the VGR concept in forward flight and pullup maneuvers, the results were compared as to performance, oscillatory blade loadings, vibratory forces transmitted to the fixed fuselage, and the rotor noise characteristics of the various VGR configurations with those of the conventional six-bladed rotor system.

Using VAPEPS for noise control on Space Station Freedom

NASA Technical Reports Server (NTRS)

Badilla, Gloria; Bergen, Thomas; Scharton, Terry

1991-01-01

Noise environmental control is an important design consideration for Space Station Freedom (SSF), both for crew safety and productivity. Acoustic noise requirements are established to eliminate fatigue and potential hearing loss by crew members from long-term exposure and to facilitate speech communication. VAPEPS (VibroAcoustic Payload Environment Prediction System) is currently being applied to SSF for prediction of the on-orbit noise and vibration environments induced in the 50 to 10,000 Hz frequency range. Various sources such as fans, pumps, centrifuges, exercise equipment, and other mechanical devices are used in the analysis. The predictions will be used in design tradeoff studies and to provide confidence that requirements will be met. Preliminary predictions show that the required levels will be exceeded unless substantial noise control measures are incorporated in the SSF design. Predicted levels for an SSF design without acoustic control treatments exceed requirements by 25 dB in some one-third octave frequency bands.

Acoustic scattering from a finite cylindrical shell with evenly spaced stiffeners: Experimental investigation

NASA Astrophysics Data System (ADS)

Liétard, R.; Décultot, D.; Maze, G.; Tran-van-Nhieu, M.

2005-10-01

The influence of evenly spaced ribs (internal rings) on the acoustic scattering from a finite cylindrical shell is examined over the dimensionless frequency range 1

Acoustic Flame Suppression Mechanics in a Microgravity Environment

NASA Astrophysics Data System (ADS)

Beisner, Eryn; Wiggins, Nathanial David; Yue, Kwok-Bun; Rosales, Miguel; Penny, Jeremy; Lockridge, Jarrett; Page, Ryan; Smith, Alexander; Guerrero, Leslie

2015-06-01

The following paper deals with acoustic flame suppression mechanics in a microgravity environment with measurements taken from an Arduino-based sensor system and validation of the technique. A Zippo lighter is ignited in microgravity and then displaced from the base of the flame and suppressed using surface interactions with single tone acoustic waves to extinguished the flame. The analysis of data collected shows that the acoustic flame suppression measurementtechniques are effective to finding qualitative differences in extinguishing in microgravity and normal gravity. Further, the results suggest that the suppression may be more effective in a microgravity environment than in a normal (1g) environment and may be a viable method of extinguishing fires during space flight.

Preliminary characterization of a one-axis acoustic system. [acoustic levitation for space processing

NASA Technical Reports Server (NTRS)

Oran, W. A.; Reiss, D. A.; Berge, L. H.; Parker, H. W.

1979-01-01

The acoustic fields and levitation forces produced along the axis of a single-axis resonance system were measured. The system consisted of a St. Clair generator and a planar reflector. The levitation force was measured for bodies of various sizes and geometries (i.e., spheres, cylinders, and discs). The force was found to be roughly proportional to the volume of the body until the characteristic body radius reaches approximately 2/k (k = wave number). The acoustic pressures along the axis were modeled using Huygens principle and a method of imaging to approximate multiple reflections. The modeled pressures were found to be in reasonable agreement with those measured with a calibrated microphone.

Fan Database and Web-tool for Choosing Quieter Spaceflight Fans

NASA Technical Reports Server (NTRS)

Allen, Christopher S.; Burnside, Nathan J.

2007-01-01

One critical aspect of designing spaceflight hardware is the selection of fans to provide the necessary cooling. And with efforts to minimize cost and the tendancy to be conservative with the amount of cooling provided, it is easy to choose an overpowered fan. One impact of this is that the fan uses more energy than is necessary. But, the more significant impact is that the hardware produces much more acoustic noise than if an optimal fan was chosen. Choosing the right fan for a specific hardware application is no simple task. It requires knowledge of cooling requirements and various fan performance characteristics as well as knowledge of the aerodynamic losses of the hardware in which the fan is to be installed. Knowledge of the acoustic emissions of each fan as a function of operating condition is also required in order to choose a quieter fan for a given design point. The purpose of this paper is to describe a database and design-tool that have been developed to aid spaceflight hardware developers in choosing a fan for their application that is based on aerodynamic performance and reduced acoustic emissions as well. This web-based-tool provides a limited amount of fan-data, provides a method for selecting a fan based on its projected operating point, and also provides a method for comparing and contrasting aerodynamic performance and acoustic data from different fans. Drill-down techniques are used to display details of the spectral noise characteristics of the fan at specific operation conditions. The fan aerodynamic and acoustic data were acquired at Ames Research Center in the Experimental Aero-Physics Branch's Anechoic Chamber. Acoustic data were acquired according to ANSI Standard S12.11-1987, "Method for the Measurement of Noise Emitted by Small Air-Moving Devices." One significant improvement made to this technique included automation that allows for a significant increase in flow-rate resolution. The web-tool was developed at Johnson Space Center and is based on the web-development application, SEQUEL, which includes graphics and drill-down capabilities. This paper will describe the type and amount of data taken for the fans and will give examples of this data. This paper will also describe the data-tool and gives examples of how it can be used to choose quieter fans for use in spaceflight hardware.

Nonminimal Einstein-Yang-Mills-Higgs theory: Associated, color, and color-acoustic metrics for the Wu-Yang monopole model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balakin, A. B.; Zayats, A. E.; Dehnen, H.

2007-12-15

We discuss a nonminimal Einstein-Yang-Mills-Higgs model with uniaxial anisotropy in the group space associated with the Higgs field. We apply this theory to the problem of propagation of color and color-acoustic waves in the gravitational background related to the nonminimal regular Wu-Yang monopole.

Formant Centralization Ratio: A Proposal for a New Acoustic Measure of Dysarthric Speech

ERIC Educational Resources Information Center

Sapir, Shimon; Ramig, Lorraine O.; Spielman, Jennifer L.; Fox, Cynthia

2010-01-01

Purpose: The vowel space area (VSA) has been used as an acoustic metric of dysarthric speech, but with varying degrees of success. In this study, the authors aimed to test an alternative metric to the VSA--the "formant centralization ratio" (FCR), which is hypothesized to more effectively differentiate dysarthric from healthy speech and register…

Analysis of laryngeal amyloidosis using high speed digital phonoscopy and acoustics (Conference Presentation)

NASA Astrophysics Data System (ADS)

Blanco, Matthew; Cruz, Raul M.; Izdebski, Krzysztof; Yan, Yuling

2017-02-01

Amyloidosis is an unknown pathogenic process in which abnormally folded proteins are deposited in the extracellular space as macroscopic aggregates. Laryngeal deposits of these proteins are extremely rare, but primarily cause dysphonia in patients. High Speed Digital Phonoscopy (HSDP) was used to capture the kinematics of vocal folds in a patient with laryngeal amyloidosis. Acoustic data was also recorded and both HSDP and acoustics were processed using custom Vocalizer® software to help elucidate the physiological impact of amyloids in the larynx, especially in regards to effects on the voice.

Oblique incidence sound absorption of porous materials covered by perforated metal and exposed to tangential airflow

NASA Technical Reports Server (NTRS)

Soderman, Paul T.

1982-01-01

The purpose of this study was to evaluate several acoustic linings that are candidate designs for the Ames 40- by 80-Foot Wind Tunnel test section. The acoustic treatment will be used to reduce wall reflections from aircraft model noise sources. The goal is not simply to attenuate sound propagating down the duct, but rather to create a semi-anechoic space in a windy environment by absorbing at least 80% of the incident acoustic energy over a wide frequency range, if possible.

Developing a system for blind acoustic source localization and separation

NASA Astrophysics Data System (ADS)

Kulkarni, Raghavendra

This dissertation presents innovate methodologies for locating, extracting, and separating multiple incoherent sound sources in three-dimensional (3D) space; and applications of the time reversal (TR) algorithm to pinpoint the hyper active neural activities inside the brain auditory structure that are correlated to the tinnitus pathology. Specifically, an acoustic modeling based method is developed for locating arbitrary and incoherent sound sources in 3D space in real time by using a minimal number of microphones, and the Point Source Separation (PSS) method is developed for extracting target signals from directly measured mixed signals. Combining these two approaches leads to a novel technology known as Blind Sources Localization and Separation (BSLS) that enables one to locate multiple incoherent sound signals in 3D space and separate original individual sources simultaneously, based on the directly measured mixed signals. These technologies have been validated through numerical simulations and experiments conducted in various non-ideal environments where there are non-negligible, unspecified sound reflections and reverberation as well as interferences from random background noise. Another innovation presented in this dissertation is concerned with applications of the TR algorithm to pinpoint the exact locations of hyper-active neurons in the brain auditory structure that are directly correlated to the tinnitus perception. Benchmark tests conducted on normal rats have confirmed the localization results provided by the TR algorithm. Results demonstrate that the spatial resolution of this source localization can be as high as the micrometer level. This high precision localization may lead to a paradigm shift in tinnitus diagnosis, which may in turn produce a more cost-effective treatment for tinnitus than any of the existing ones.

Theoretical Acoustic Absorber Design Approach for LOX/LCH4 Pintle Injector Rocket Engines

NASA Astrophysics Data System (ADS)

Candelaria, Jonathan

Liquid rocket engines, or LREs, have served a key role in space exploration efforts. One current effort involves the utilization of liquid oxygen (LOX) and liquid methane (LCH4) LREs to explore Mars with in-situ resource utilization for propellant production. This on-site production of propellant will allow for greater payload allocation instead of fuel to travel to the Mars surface, and refueling of propellants to travel back to Earth. More useable mass yields a greater benefit to cost ratio. The University of Texas at El Paso's (UTEP) Center for Space Exploration and Technology Research Center (cSETR) aims to further advance these methane propulsion systems with the development of two liquid methane - liquid oxygen propellant combination rocket engines. The design of rocket engines, specifically liquid rocket engines, is complex in that many variables are present that must be taken into consideration in the design. A problem that occurs in almost every rocket engine development program is combustion instability, or oscillatory combustion. It can result in the destruction of the rocket, subsequent destruction of the vehicle and compromise the mission. These combustion oscillations can vary in frequency from 100 to 20,000 Hz or more, with varying effects, and occur from different coupling phenomena. It is important to understand the effects of combustion instability, its physical manifestations, how to identify the instabilities, and how to mitigate or dampen them. Linear theory methods have been developed to provide a mathematical understanding of the low- to mid-range instabilities. Nonlinear theory is more complex and difficult to analyze mathematically, therefore no general analytical method that yields a solution exists. With limited resources, time, and the advice of our NASA mentors, a data driven experimental approach utilizing quarter wave acoustic dampener cavities was designed. This thesis outlines the methodology behind the design of an acoustic dampening system for a 500 lbf and a 2000 lbf throttleable liquid oxygen liquid methane pintle injector rocket engine.

Children's Acoustic and Linguistic Adaptations to Peers With Hearing Impairment.

PubMed

Granlund, Sonia; Hazan, Valerie; Mahon, Merle

2018-05-17

This study aims to examine the clear speaking strategies used by older children when interacting with a peer with hearing loss, focusing on both acoustic and linguistic adaptations in speech. The Grid task, a problem-solving task developed to elicit spontaneous interactive speech, was used to obtain a range of global acoustic and linguistic measures. Eighteen 9- to 14-year-old children with normal hearing (NH) performed the task in pairs, once with a friend with NH and once with a friend with a hearing impairment (HI). In HI-directed speech, children increased their fundamental frequency range and midfrequency intensity, decreased the number of words per phrase, and expanded their vowel space area by increasing F1 and F2 range, relative to NH-directed speech. However, participants did not appear to make changes to their articulation rate, the lexical frequency of content words, or lexical diversity when talking to their friend with HI compared with their friend with NH. Older children show evidence of listener-oriented adaptations to their speech production; although their speech production systems are still developing, they are able to make speech adaptations to benefit the needs of a peer with HI, even without being given a specific instruction to do so. https://doi.org/10.23641/asha.6118817.

Reflected wavefront manipulation based on ultrathin planar acoustic metasurfaces

PubMed Central

Li, Yong; Liang, Bin; Gu, Zhong-ming; Zou, Xin-ye; Cheng, Jian-chun

2013-01-01

The introduction of metasurfaces has renewed the Snell's law and opened up new degrees of freedom to tailor the optical wavefront at will. Here, we theoretically demonstrate that the generalized Snell's law can be achieved for reflected acoustic waves based on ultrathin planar acoustic metasurfaces. The metasurfaces are constructed with eight units of a solid structure to provide discrete phase shifts covering the full 2π span with steps of π/4 by coiling up the space. By careful selection of the phase profiles in the transverse direction of the metasurfaces, some fascinating wavefront engineering phenomena are demonstrated, such as anomalous reflections, conversion of propagating waves into surface waves, planar aberration-free lens and nondiffracting Bessel beam generated by planar acoustic axicon. Our results could open up a new avenue for acoustic wavefront engineering and manipulations. PMID:23986034

Dynamic loads on twin jet exhaust nozzles due to shock noise

NASA Technical Reports Server (NTRS)

Norum, T. D.; Shearin, J. G.

1986-01-01

Acoustic near field data were collected with model single and twin jet nozzles to determine if closely spaced nozzles produce higher acoustic loading than do single nozzles. The tests were spurred by structural failure of the B-1 exhaust nozzle external flaps and similar damage on the F-15. The test was performed using two 5/8 in. ID pipes machined and placed side-by-side to mimic B-1 nozzles. A microphone mounted on the internozzle fairing measured acoustic levels near the nozzle exit plane. The nozzles oscillated significantly more than did a single nozzle over a wide range of nozzle pressure ratios. Acoustic levels in the dual jets exceeded single jet noise by as much as 20 dB, making acoustic resonance a definite candidate for structural damage in the twin jet configuration.

Aircraft wake vortex measurements at Denver International Airport

DOT National Transportation Integrated Search

2004-05-10

Airport capacity is constrained, in part, by spacing requirements associated with the wake vortex hazard. NASA's Wake Vortex Avoidance Project has a goal to establish the feasibility of reducing this spacing while maintaining safety. Passive acoustic...

Open cycle traveling wave thermoacoustics: mean temperature difference at the regenerator interface.

PubMed

Weiland, Nathan T; Zinn, Ben T

2003-11-01

In an open cycle traveling wave thermoacoustic engine, the hot heat exchanger is replaced by a steady flow of hot gas into the regenerator to provide the thermal energy input to the engine. The steady-state operation of such a device requires that a potentially large mean temperature difference exist between the incoming gas and the solid material at the regenerator's hot side, due in part to isentropic gas oscillations in the open space adjacent to the regenerator. The magnitude of this temperature difference will have a significant effect on the efficiencies of these open cycle devices. To help assess the feasibility of such thermoacoustic engines, a numerical model is developed that predicts the dependence of the mean temperature difference upon the important design and operating parameters of the open cycle thermoacoustic engine, including the acoustic pressure, mean mass flow rate, acoustic phase angles, and conductive heat loss. Using this model, it is also shown that the temperature difference at the regenerator interface is approximately proportional to the sum of the acoustic power output and the conductive heat loss at this location.

Hierarchical Assembly of Tungsten Spheres and Epoxy Composites in Three-Dimensional Graphene Foam and Its Enhanced Acoustic Performance as a Backing Material.

PubMed

Qiu, Yunfeng; Liu, Jingjing; Lu, Yue; Zhang, Rui; Cao, Wenwu; Hu, PingAn

2016-07-20

Backing materials play important role in enhancing the acoustic performance of an ultrasonic transducer. Most backing materials prepared by conventional methods failed to show both high acoustic impedance and attenuation, which however determine the bandwidth and axial resolution of acoustic transducer, respectively. In the present work, taking advantage of the structural feature of 3D graphene foam as a confined space for dense packing of tungsten spheres with the assistance of centrifugal force, the desired structural requirement for high impedance is obtained. Meanwhile, superior thermal conductivity of graphene contributes to the acoustic attenuation via the conversion of acoustic waves to thermal energy. The tight contact between tungstate spheres, epoxy matrix, or graphene makes the acoustic wave depleted easily for the absence of air barrier. The as-prepared 3DG/W80 wt %/epoxy film in 1 mm, prepared using ∼41 μm W spheres in diameter, not only displays acoustic impedance of 13.05 ± 0.11 MRayl but also illustrates acoustic attenuation of 110.15 ± 1.23 dB/cm MHz. Additionally, the composite film exhibits a high acoustic absorption coefficient, which is 94.4% at 1 MHz and 100% at 3 MHz, respectively. Present composite film outperforms most of the reported backing materials consisting of metal fillers/polymer blending in terms of the acoustic impedance and attenuation.

Research pressure instrumentation for NASA Space Shuttle main engine, modification no. 5

NASA Technical Reports Server (NTRS)

Anderson, P. J.; Nussbaum, P.; Gustafson, G.

1984-01-01

The objective of the research project described is to define and demonstrate methods to advance the state of the art of pressure sensors for the space shuttle main engine (SSME). Silicon piezoresistive technology was utilized in completing tasks: generation and testing of three transducer design concepts for solid state applications; silicon resistor characterization at cryogenic temperatures; experimental chip mounting characterization; frequency response optimization and prototype design and fabrication. Excellent silicon sensor performance was demonstrated at liquid nitrogen temperature. A silicon resistor ion implant dose was customized for SSME temperature requirements. A basic acoustic modeling software program was developed as a design tool to evaluate frequency response characteristics.

Acoustic Source Bearing Estimation (ASBE) computer program development

NASA Technical Reports Server (NTRS)

Wiese, Michael R.

1987-01-01

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

Influence of Architectural Features and Styles on Various Acoustical Measures in Churches

NASA Astrophysics Data System (ADS)

Carvalho, Antonio Pedro Oliveira De.

This work reports on acoustical field measurements made in a major survey of 41 Catholic churches in Portugal that were built in the last 14 centuries. A series of monaural and binaural acoustical measurements was taken at multiple source/receiver positions in each church using the impulse response with noise burst method. The acoustical measures were Reverberation Time (RT), Early Decay Time (EDT), Clarity (C80), Definition (D), Center Time (TS), Loudness (L), Bass Ratios based on the Reverberation Time and Loudness rm (BR_-RT and rm BR_-L), Rapid Speech Transmission Index (RASTI), and the binaural Coherence (COH). The scope of this research is to investigate how the acoustical performance of Catholic churches relates to their architectural features and to determine simple formulas to predict acoustical measures by the use of elementary architectural parameters. Prediction equations were defined among the acoustical measures to estimate values at individual locations within each room as well as the mean values in each church. Best fits with rm R^2~0.9 were not uncommon among many of the measures. Within and interchurch differences in the data for the acoustical measures were also analyzed. The variations of RT and EDT were identified as much smaller than the variations of the other measures. The churches tested were grouped in eight architectural styles, and the effect of their evolution through time on these acoustical measures was investigated. Statistically significant differences were found regarding some architectural styles that can be traced to historical changes in Church history, especially to the Reformation period. Prediction equations were defined to estimate mean acoustical measures by the use of fifteen simple architectural parameters. The use of the Sabine and Eyring reverberation time equations was tested. The effect of coupled spaces was analyzed, and a new algorithm for the application of the Sabine equation was developed, achieving an average of 16% in the differences between the predicted and real RTs. Using binaural measurements and subjective information collected in these churches, BACH (Binaural Acoustical CoHerence), a new binaural measure, is presented. A linear correlation coefficient near 0.7 was found between BACH and the subjective quality ratings, supporting the hypothesis that it can be useful in predicting the quality of music in churches. In conclusion, this study revealed important acoustical and architectural parameters and their relations, providing the basic information to predict several acoustical measures in churches at early stages of design or without the need of measurements in the real buildings.

ACOSS Eleven (Active Control of Space Structures). Volume 1.

DTIC Science & Technology

1983-07-01

Dr. Keto Soosaar (617) 258-2575 Project Engineer: Richard Carman (315) 330-3148 Approved for public release; distribution unlimited This research was...the Department of Defense and monitored by the Rome Air Development Center. The program manager is Dr. Keto Soosaar and the project leader for...Scharf, "Covariant Invariant Digital Filters," IEEE Trans. Acoust., Speech, Signal Proc., Vol. ASSP-25, No. 2, April 1977, pp. 143 -151. 55 h

Noise Transmission Studies of an Advanced Grid-Stiffened Composite Fairing

DTIC Science & Technology

2007-10-01

increase in blanket thickness and weight [7]. The evolved expendable launch vehicle (EELV) programs have conducted research to ensure that their launch...uses an aluminum fairing that is 4 to 5 m in diameter. The Atlas V 500 and heavy lift vehicles use a fairing designed and built by Contraves , which...builds the Ariane V launch vehicle for the European Space Agency. Contraves developed an innovative acoustic blanket for fairing noise reduction that

Cicadas impact bird communication in a noisy tropical rainforest

PubMed Central

Hall, Robert; Ray, William; Beck, Angela; Zook, James

2015-01-01

Many animals communicate through acoustic signaling, and “acoustic space” may be viewed as a limited resource that organisms compete for. If acoustic signals overlap, the information in them is masked, so there should be selection toward strategies that reduce signal overlap. The extent to which animals are able to partition acoustic space in acoustically diverse habitats such as tropical forests is poorly known. Here, we demonstrate that a single cicada species plays a major role in the frequency and timing of acoustic communication in a neotropical wet forest bird community. Using an automated acoustic monitor, we found that cicadas vary the timing of their signals throughout the day and that the frequency range and timing of bird vocalizations closely track these signals. Birds significantly avoid temporal overlap with cicadas by reducing and often shutting down vocalizations at the onset of cicada signals that utilize the same frequency range. When birds do vocalize at the same time as cicadas, the vocalizations primarily occur at nonoverlapping frequencies with cicada signals. Our results greatly improve our understanding of the community dynamics of acoustic signaling and reveal how patterns in biotic noise shape the frequency and timing of bird vocalizations in tropical forests. PMID:26023277