SEARCH · Search NASA

Results for “Sound Localization”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22

All sources NASA NTRS DOE OSTI

NASA NTRS2002

Simplify and Succeed

In the early 70's the management at the American Stock Exchange wanted a set of automated displays installed on the trading floor. The purpose of the displays was to announce to the public all changes related to the trading of equities. I had exactly three months to get the work done. Because of local building codes, I was told that the displays that met the specifications would not be available until nine months after the order was placed. This was not acceptable to the Exchange's management. The project team was in a quandary. I called a meeting to discuss the situation and develop a report explaining why we needed more time. Jokingly, I suggested, 'Why not use picket signs?' The Exchange had just gone through some painful labor negotiations. To anyone who had been involved in those negotiations, the thought of a picket sign should have sounded, I thought, like gallows humor. This was not acceptable to the Exchange's management. To my surprise, the rest of the project team took the idea seriously.

Levine, Art↗

NASA NTRS2012

In Situ Detection of Strong Langmuir Turbulence Processes in Solar Type III Radio Bursts

The high time resolution observations obtained by the WAVES experiment of the STEREO spacecraft in solar type III radio bursts show that Langmuir waves often occur as intense localized wave packets. These wave packets are characterized by short durations of only a few ms and peak intensities, which well exceed the supersonic modulational instability (MI) thresholds. These timescales and peak intensities satisfy the criterion of the solitons collapsed to spatial scales of a few hundred Debye lengths. The spectra of these wave packets consist of primary spectral peaks corresponding to beam-resonant Langmuir waves, two or more sidebands corresponding to down-shifted and up-shifted daughter Langmuir waves, and low frequency enhancements below a few hundred Hz corresponding to daughter ion sound waves. The frequencies and wave numbers of these spectral components satisfy the resonance conditions of the modulational instability (MI). Moreover, the tricoherences, computed using trispectral analysis techniques show that these spectral components are coupled to each other with a high degree of coherency as expected of the MI type of four wave interactions. The high intensities, short scale lengths, sideband spectral structures and low frequency spectral enhancements and, high levels of tricoherences amongst the spectral components of these wave packets provide unambiguous evidence for the supersonic MI and related strong turbulence processes in type III radio bursts. The implication of these observations include: (1) the MI and related strong turbulence processes often occur in type III source regions, (2) the strong turbulence processes probably play very important roles in beam stabilization as well as conversion of Langmuir waves into escaping radiation at the fundamental and second harmonic of the electron plasma frequency, fpe, and (3) the Langmuir collapse probably follows the route of MI in type III radio bursts.

Langmuir↗

NASA NTRS2024

An Annoyance Model for Urban Air Mobility Vehicle Noise in the Presence of a Masker

Proposed Urban Air Mobility (UAM) operations offer an alternative to road and rail traffic for local and regional movement of people and goods. To allow for large-scale adoption of UAM vertical takeoff and landing (VTOL) aircraft, it is critical to predict human annoyance response to the acoustic noise generated by these vehicles. We propose a model that predicts an individual’s perceived level of annoyance when presented with UAM VTOL aircraft noise in the context of a representative masking noise. The annoyance model is based on the psychoacoustic annoyance model of Fastl and Zwicker (Zwicker and Fastl, 1999), with an additional tonality term based on subjective testing of UAM sound quality (Boucher, et al., 2023). The model also predicts changes in annoyance when UAM noise is masked by a background sound, based on subjective evaluation of detection, noticeability, and annoyance of noise in the presence of a masker.

Noise↗

NASA NTRS2000

Possibilities of Using MARSES Instrument for Long-Term Monitoring and Subsurface Studies in Arctic and Arid Lands

The Mars Electromagnetic Sounding Experiment (MARSES) is the sounding instrument developed of searching for groundwater, water-ice or permafrost layers existing in some depth under the visible surface in the dry lands of Mars. One of the more important challenges facing natural resource managers today is how to identify, measure and monitoring the cumulative impacts of land use decisions across space and time. The secondary task is to measure the soil properties of Martian subsurface, which includes porosity, electrical resistance of the liquid phase, thermal conductivity, temperature dependence. A main task of the MARSES monitoring system is to examine changes in the subsurface properties of local areas regolith on the Martian surface on the base of the database of various soil slices in terrestrial conditions. Additional information is contained in the original extended abstract.

Ozorovich, Y. R.↗

NASA NTRS2001

Possibilities of Using MARSES Instrument for Long-Term Monitoring and Subsurface Studies in Arctic and Arid Lands

The MARSES is the sounding instrument developed of searching for groundwater, water-ice or permafrost layers existing in some depth under the visible surface in the dry lands of Mars. One of the more important challenges facing natural resource managers today is how to identify, measure and monitoring the cumulative impacts of land use decisions across space and time. The secondary task is to measure the soil properties of Martian subsurface, which includes porosity, electrical resistance of the liquid phase, thermal conductivity, temperature dependence. A main task of the MARSES monitoring system is to examine changes in the subsurface properties of local areas regolith on the Martian surface on the base of the database of various soil slices in terrestrial conditions

Ozorovich, Y. R.↗

NASA NTRS1999

Candidate-Landing Sites and Backups for the Mars Surveyor Program in the Schiaparelli. Crater Region

Our Survey area comprises the Sinus Sabeus NW quadrangle that includes most of the Schiaparelli crater and part of the Arabia SW region (3 N to 15 S Lat.) and (0 to 337.5 W long.) and covers all regions that show a potential hydrogeological link with the Schiaparelli impact structure. This area is hereafter defined as the Schiaparelli Crater Region. The Schiaparelli crater region is one of the most documented MOC targets. Up to now, MGS MOC camera took two dozen images at an average of 5m/pxl resolution that not only provide an exceptional insight on the local geology and morphology, but give also key-elements to assess landing safety criteria. In addition, the MOLA topographic profile No. 23 passes through part of the crater basin allowing the adjustment of the elevation as previously known from the Viking mission (USGS I-2125, 1991). Beyond the Mars Polar Lander mission that will land next December, the future missions (2001 APEX, 2003, and 2005) are led by a series of science objectives and engineering constraints that must be considered in order to select landing sites that will fulfill the Surveyor Program's objectives. The search for a sound and safe candidate-site (without ending up with the usual "safe but boring" or "fascinating but too risky" site) is usually limited by the data available to the investigator, by the data accuracy (e.g. poor image resolution, poor altimetry), and the lack of crucial information for science and safety that can be derived from them. The Schiaparelli region provides an exception to this recurrent pattern. We listed the preliminary constraints for landing site selection identified for the Surveyor '01 mission, in terms of safety requirements and data needed and compared them against the existing information and/or data already available for the Schiaparelli region. The engineering constraints of '03 and '05 are not designated yet but, since they are also related to atmospheric density and Lander designs, we will assume that these points will be comparable to '01. The main difference will reside in the rover design, the Rocky-7 class rover being bigger than Marie Curie ('01) will be able to overcome bigger obstacles. We listed then the main objectives of the Surveyor Program and compared them with the potential offered by the Schiaparelli Crater Region to document them. Within the survey area, the Schiaparelli impact crater is 2.5 S/343.3 W (USGS 1-1376, MC-20 NW, 1981) and occupies a significant surface area. The crater has been proposed as a potential candidate-site in the past years. The purpose of this study is to show that, not only the Schiaparelli Crater would be a high-priority target, but that the region where it is located offer several very-high potential back-up sites, all within science and engineering constraints, that make this region probably the most promising candidate area so far.

Cabrol, Nathalie A.↗

NASA NTRS2006

Analysis of Acoustic Modeling and Sound Propagation in Aircraft Noise Prediction

An analysis has been performed of measured and predicted aircraft noise levels around Denver International Airport. A detailed examination was made of 90 straight-out departures that yielded good measurements on multiple monitors. Predictions were made with INM 5, INM 6 and the simulation model NMSIM. Predictions were consistently lower than measurements, less so for the simulation model than for the integrated models. Lateral directivity ("installation effect") patterns were seen which are consistent with other recent measurements. Atmospheric absorption was determined to be a significant factor in the underprediction. Calculations of atmospheric attenuation were made over a full year of upper air data at seven locations across the United States. It was found that temperature/humidity effects could cause variations of up to +/-4 dB, depending on season, for the sites examined. It was concluded that local temperature and humidity should be accounted for in aircraft noise modeling.

Plotkin, Kenneth J.↗

NASA NTRS1992

SAGE II stratospheric density and temperature retrieval experiment

This paper describes a stratospheric density and temperature retrieval experiment based on the solar occultation measurement of the Stratospheric Aerosol and Gas Experiment (SAGE II). The entire retrieval analysis involves two inversion steps: the vertical structure inversion, which derives the profile of local atmospheric extinction from SAGE II limb optical depth data, and the species inversion, which inverts the concentration of air molecules, aerosols, ozone, and nitrogen dioxide from the derived atmospheric extinction at five SAGE II short wavelengths (0.385, 0.448, 0.453, 0.525, and 0.600 microns). The derived density profile is then used to infer the temperature distribution, assuming that the atmosphere is in hydrostatic equilibrium and obeys the ideal gas law. The temperature profiles retrieved from the SAGE II observations are compared with near-coincident, in both time and space, French Rayleigh lidar and NASA Wallops Flight Facility rocket datasonde soundings as well as the National Meteorological Center (NMC) data analyses. The results indicate that the mean SAGE II temperature agrees with the mean lidar measurements to within 2 C at altitudes from 30.5 to 52.5 km. The SAGE II and datasonde observations agree to within about 4 C in approximately the same altitude region.

Wang, Pi-Huan↗

NASA NTRS2008

Using Hyperspectral Imagery to Identify Turfgrass Stresses

The use of a form of remote sensing to aid in the management of large turfgrass fields (e.g. golf courses) has been proposed. A turfgrass field of interest would be surveyed in sunlight by use of an airborne hyperspectral imaging system, then the raw observational data would be preprocessed into hyperspectral reflectance image data. These data would be further processed to identify turfgrass stresses, to determine the spatial distributions of those stresses, and to generate maps showing the spatial distributions. Until now, chemicals and water have often been applied, variously, (1) indiscriminately to an entire turfgrass field without regard to localization of specific stresses or (2) to visible and possibly localized signs of stress for example, browning, damage from traffic, or conspicuous growth of weeds. Indiscriminate application is uneconomical and environmentally unsound; the amounts of water and chemicals consumed could be insufficient in some areas and excessive in most areas, and excess chemicals can leak into the environment. In cases in which developing stresses do not show visible signs at first, it could be more economical and effective to take corrective action before visible signs appear. By enabling early identification of specific stresses and their locations, the proposed method would provide guidance for planning more effective, more economical, and more environmentally sound turfgrass-management practices, including application of chemicals and water, aeration, and mowing. The underlying concept of using hyperspectral imagery to generate stress maps as guides to efficient management of vegetation in large fields is not new; it has been applied in the growth of crops to be harvested. What is new here is the effort to develop an algorithm that processes hyperspectral reflectance data into spectral indices specific to stresses in turfgrass. The development effort has included a study in which small turfgrass plots that were, variously, healthy or subjected to a variety of controlled stresses were observed by use of a hand-held spectroradiometer. The spectroradiometer readings in the wavelength range from 350 to 1,000 nm were processed to extract hyperspectral reflectance data, which, in turn, were analyzed to find correlations with the controlled stresses. Several indices were found to be correlated with drought stress and to be potentially useful for identifying drought stress before visible symptoms appear.

Hutto, Kendall↗

NASA NTRS2009

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

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

Tian, Jialin↗

NASA NTRS2002

Photoevaporation of Clumps in Photodissociation Regions

We present the results of an investigation of the effects of Far Ultraviolet (FUV) radiation (6.0eV < hv < 13.6eV) from hot early type OB stars on clumps in star-forming molecular clouds. Clumps in FUV-illuminated regions (or photodissociation regions or PDRs) undergo external heating and photodissociation as they are exposed to the FUV field, resulting in a loss of cold, molecular lump mass as it is converted to warm atomic gas. The heating, if rapid, creates strong photoevaporative mass flows off the clump surfaces, and drives shocks into the clumps, compressing them to high densities. The clumps lose mass on relatively short timescales. The evolution of an individual clump is found to be sensitive to three dimensionless parameters: Nc0, the ratio of the initial column density of the clump to the column N(0) approx. 10(exp 21) cm(exp -2) of a warm FUV-heated surface region; upsilon, the ratio of the sound speed in the heated surface to that in the cold clump material: and t(FUV)t(c), the ratio of the "turn-on time" t(FUV) of the heating flux on a clump to its initial sound crossing-time t(c). The evolution also depends on whether a confining interclump medium exists, or whether the interclump region has negligible pressure, as is the case for turbulence-generated clumps. In this paper, we use spherical 1-D numerical hydrodynamic models as well as approximate analytical models to study the dependence of clump photoevaporation on the physical parameters of the clump, and to derive the dynamical evolution, mass loss rates and photoevaporative timescales of a clump for a variety of astrophysical situations. Turbulent clumps evolve so that their column densities are equal to a critical value determined by the local FUV field, and typically have short photo evaporation timescales, approx. 10(exp 4-5) years for a 1 M(solar mass) clump in a typical star-forming region (Nc0 = 10, upsilon = 10). Clumps with insufficient magnetic pressure support, and in strong FUV fields may be driven to collapse by the compressional effect of converging shock waves. We also estimate the rocket effect on photoevaporating clumps and find that it is significant only for the smallest clumps, with sizes much less than the extent of the PDR itself. Clumps that are confined by all interclump medium may either get completely photoevaporated, or may preserve a shielded core with a warm, dissociated, protective shell that, absorbs the incident FUV flux. We compare our results with observations of some well studied PDRs: the Orion Bar, M17SW NGC 2023 and the Rosette Nebula. The data are consistent with both interpretations of clump origin. turbulence and pressure confinement, with a slight indication for favouring the turbulent model for clumps over pressure-confined

Gorti, Uma↗

NASA NTRS1982

Large sounding rockets as a base for probing the distant magnetosphere

The Echo program's use of large sounding rockets to inject electron beams into the outer trapping region where the earth's plasma sheet interacts with the inner magnetosphere is discussed. The beams pass through the plasma sheet and the trapping region, reflect at the southern hemisphere conjugate point and return to the vicinity of the rocket where they are detected and analyzed for acceleration and diffusion processes which may also be responsible for the radiation belts. The motion of electron beams in the magnetosphere is discussed from the standpoint of single particle motion, and the trajectories of electrons injected with known energy, known angle between the electron velocity vector and the local magnetic field vector, and known position are examined. The interaction between the rocket motion and the electron drift motion is described, and the advantages and drawbacks of beam detection by optical methods and by throwaway detectors are compared. Planned Echo experiments using the Space Shuttle are discussed

Winckler, J. R.↗

NASA NTRS1994

Zero potential vorticity envelopes for the zonal-mean velocity of the Venus/Titan atmospheres

The diagnostic analysis of numerical simulations of the Venus/Titan wind regime reveals an overlooked constraint upon the latitudinal structure of their zonal-mean angular momentum. The numerical experiments, as well as the limited planetary observations, are approximately consistent with the hypothesis that within the latitudes bounded by the wind maxima the total Ertel potential vorticity associated with the zonal-mean motion is approximately well mixed with respect to the neutral equatorial value for a stable circulation. The implied latitudinal profile of angular momentum is of the form M equal to or less than M(sub e)(cos lambda)(exp 2/Ri), where lambda is the latitude and Ri the local Richardson number, generally intermediate between the two extremes of uniform angular momentum (Ri approaches infinity) and uniform angular velocity (Ri = 1). The full range of angular momentum profile variation appears to be realized within the observed meridional - vertical structure of the Venus atmosphere, at least crudely approaching the implied relationship between stratification and zonal velocity there. While not itself indicative of a particular eddy mechanism or specific to atmospheric superrotation, the zero potential vorticity (ZPV) constraint represents a limiting bound for the eddy - mean flow adjustment of a neutrally stable baroclinic circulation and may be usefully applied to the diagnostic analysis of future remote sounding and in situ measurements from planetary spacecraft.

Allison, Michael↗

NASA NTRS1974

Further evidence for an interstellar source of nighttime He I 584 A radiation

The intensity of He I, 584 A radiation in the night sky was measured from a sounding rocket at altitudes between 160 and 217 km. The results obtained confirm previous measurements of this radiation. The observed intensity and spatial variations can be entirely accounted for by resonance scattering of solar 584 A radiation from interstellar helium. The best fit to the observations in this case is obtained with an interstellar helium model in which the bulk velocity of the gas is 5 km/sec, the temperature is 10,000 K, and the helium number density is 0.032 per cu cm. Even if a geocoronal scattering component is present, the data can be used to set a lower limit to the temperature of the local interstellar medium of 1,500 (plus or minus 500) K, assuming a normal interstellar helium abundance.

Paresce, F.↗

NASA NTRS1995

Emission line signatures of anisotropic turbulence in accretion disks

We investigate observable effects of anisotropic turbulence on the velocity profiles and eclipse behavior of emission lines from accretion disks. Turbulence expands the local line broadening profile, enhancing the surface brightness of saturated emission lines. Anisotropic turbulence produces anisotropic emission in such lines. The effects become observable when the turbulence exceeds the thermal velocity. Each term in the velocity-velocity correlation matrix produces a distinctive azimuthal pattern of enhanced emission-line surface brightness on the face of the accretion disk. These patterns express themselves as changes in the observable shapes of the disk's emission lines. The best place to look for turbulence effects is in saturated emission lines of heavy elements such as Ca, Mg, and Fe, which have a smaller thermal velocity at a given sound speed and at moderate inclination (60-70 degrees), since the Keplerian shear broadening dominates at higher inclinations.

Horne, Keith↗

NASA NTRSDate not supplied

How Well Satellite Remote Sensing Can Inform Surface Level Ozone Production Sensitivity to Precursor Trace Gas Emissions?

Surface-level ozone (O3) pollution mitigation strategies rely on a clear understanding of the atmospheric chemical processes involving O3, NOx (nitric oxide (NO) + nitrogen dioxide (NO2)) and volatile organic compounds (VOCs). A robust spatiotemporal classification of O3 photochemical regimes with relative chemical sensitivity of local O3 formation to emission reductions of NOx (NOx-limited regime) versus VOCs (radical-limited regime) is required to design anthropogenic emission reduction policies in order to improve surface air quality. Numerous studies found that the ratio of satellite-retrieved Vertical Column Densities (VCDs) of formaldehyde (HCHO) to NO2 can diagnose O3 production sensitivity. However, uncertainty still remains about the accuracy of such estimates using satellite-based retrievals. This study conducts an investigation to identify how well satellite data can inform surface-level O3 sensitivity by validating satellite-based estimates against aircraft-based retrievals taken during the Long Island Sound Tropospheric Ozone Study (LISTOS-2018) and Ozone Water-Land Environmental Transition Study (OWLETS-2) field campaigns. For this study, we use HCHO and NO2 retrievals from the Ozone Monitoring Instrument (OMI) onboard the Aura satellite, and high spatiotemporal resolution TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor (S5P) satellite. The Community Multiscale Air Quality (CMAQ) modelling system is used to provide trace gas vertical profiles to recalculate air mass factor for deriving consistent satellite-based VCDs. To demonstrate the ability of satellites to diagnose O3 production regimes, we validate satellite-derived O3 sensitivity regimes, along with the OMI and TROPOMI products applied, using HCHO and NO2 retrievals from the aircraft-based instruments: Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) spectrometer and Geostationary Coastal and Air Pollution Events Airborne Simulator (GCAS) instruments deployed during the LISTOS-2018 and OWLETS-2 campaigns. The results of this work will advance our fundamental knowledge of the spatiotemporal evolution of the complex O3-NOx-VOC chemistry, and will advance our understanding about the quality of remote-sensing, suborbital, and satellite data for accurately observing surface-level O3 production sensitivity.

Satellite↗

NASA NTRS1995

Acoustic wave propagation in the solar atmosphere 1. Rediscussion of the linearized theory including nonstationary solutions

The normal dispersion analysis for linear adiabatic wave propagation in stratified atmospheres adopts a real frequency and solves for the complex vertical wavenumber. We show that an exponentially stratified atmosphere does not have any spatially bounded normal modes for real frequencies. The usual treatment involves a representation where the imaginary part of the vertical wavenumber yields a rho(sup -1/2) dependence of the velocity amplitude which diverges as the absolute value of z approaches infinity. This solution includes a cutoff frequency below which acoustic modes cannot propagate. The standard dispersion analysis is a local representation of the wave behavior in both space and time but which is assumed to represent the motion throughout - infinity is less than t is less than infinity and 0 is less than infinity. However, any solution which has a purely sinusoidal time dependence extends through this full domain and is divergent due to the rho(sup -1/2) dependence. We show that a proper description is in terms of a near field of a boundary piston which is driven arbitrarily as a function of space and time. The atmosphere which responds to this piston is a semi-infinite layer which has an initially constant sound speed but which has the usual gravitational stratification. In a restricted domain of space and time above this boundary, the wavelike behavior of the medium may be described by frequencies and vertical wavenumbers which are both complex. When both parameters are allowed to have imaginary components, a new range of solutions is found for which there is virtually no cutoff frequency. We show that vertical energy propagation can take place through the solar atmosphere as a result of oscillations below the nominal cutoff frequency. Previously, the largest amplitude oscillations which generally have low frequencies were dropped from the calculation of energy flux becuase their frequencies are below the cutoff frequency. This new family of near-field waves permits these modes to carry energy vertically outward and raises the possibility that the largest amplitude 5 minute oscillations play a substantial role in the transport of acoustic energy to the chromosphere.

Wang, Zhengzhi↗

NASA NTRS1999

Mars Electromagnetic Sounding Experiment: MARSES

The MARSES is the sounding instrument developed of searching for water, water-ice or permafrost layers existing in some depth under the visible surface of Mars. There are many evidences that water once was abundant on Mars. There are stream lined islands formed by flowing water, flow patterns reminiscent of wadis in Earth deserts, and outflow channels thought to have been formed by sudden outrush of subterranean water. The secondary task is to measure the soil properties of the subsurface of Mars, which include porosity, electrical resistance of the liquid phase, thermal conductivity, temperature dependence. A main task of the MARSES system is to examine changes in subsurface properties of local areas regolith on the martian surface, and to relate them to optical images and other remote sensing data in order to understand the nature of different terrain forms. The dryed up regions of Martian frozen rocks is considered to have been developing during more than 3.5 bln years, so the upper layer boundary of permafrost can serve as an indicator reflecting the course of martian paleoclimate evolution. Additional information is contained in the original extended abstract.

Ozorovich, Y. R.↗