Narrowband Data Research Articles

Three-dimensional source tracking in an uncertain environment via Bayesian marginalization

This paper develops a non-linear Bayesian marginalization approach for three-dimensional source tracking in shallow water with uncertain environmental properties. The algorithm integrates the posterior probability density via a combination of Metropolis-Hastings sampling over environmental and bearing model parameters and Gibbs sampling over source range/depth, with track constraints on source velocity applied. Marginal distributions for source range/depth and source bearing are derived, with source position uncertainties estimated from the distributions. The Viterbi algorithm is applied to obtain the most probable three-dimensional track. The approach is applied to experimental narrowband data recorded on a bottom-moored horizontal line array in the Barents Sea.

Data analysis of gravitational-wave signals from spinning neutron stars. V. A narrow-band all-sky search

We present theory and algorithms to perform an all-sky coherent search for periodic signals of gravitational waves in narrow-band data of a detector. Our search is based on a statistic, commonly called the $\mathcal{F}$-statistic, derived from the maximum-likelihood principle in Paper I of this series. We briefly review the response of a ground-based detector to the gravitational-wave signal from a rotating neuron star and the derivation of the $\mathcal{F}$-statistic. We present several algorithms to calculate efficiently this statistic. In particular our algorithms are such that one can take advantage of the speed of fast Fourier transform (FFT) in calculation of the $\mathcal{F}$-statistic. We construct a grid in the parameter space such that the nodes of the grid coincide with the Fourier frequencies. We present interpolation methods that approximately convert the two integrals in the $\mathcal{F}$-statistic into Fourier transforms so that the FFT algorithm can be applied in their evaluation. We have implemented our methods and algorithms into computer codes and we present results of the Monte Carlo simulations performed to test these codes.

Interactive free-form level-set surface-editing operators

We present a set of interactive, free-form editing operators for direct manipulation of level-set models that supports the creation and removal of surface detail. The mathematics, data structures and algorithms needed to implement numerous level-set modeling capabilities have been developed. The first component of these capabilities identifies the region-of-influence (ROI) on the surface to be modified, and the specification of user handles, i.e. a point or a curve within the ROI, that are used to control the free-form surface edits. The editing operators include pulling the level-set surface by a handle with the surface changes occurring symmetrically around the handle or within the ROI, surface offsetting and carving, deformations towards a profile curve and localized smoothing. The editing operators are implemented with specialized speed functions, which are incorporated into the level set partial differential equation (PDE). The PDE is then evolved to produce the desired model modification. The specific form of each speed function is described in detail. The operators have been combined with an OpenGL interface and the VISPACK level-set library to create a preliminary interactive level-set modeling system. VISPACK's narrow-band data structures have been extended to localize all computations and updates to optimize running time and provide interactive performance. Additional sketch-based level-set editing operators have been implemented within the system, and are described elsewhere [1]. A variety of level-set models are presented to demonstrate the effectiveness of the editing operators.

Evaluation of solution methods for radiative heat transfer in gaseous oxy-fuel combustion environments

The exact solution to radiative heat transfer in combusting flows is not possible analytically due to the complex nature of the integro-differential radiative transfer equation (RTE). Many different approximate solution methods for the solution of the RTE in multi-dimensional problems are available. In this paper, two of the principal methods, the spherical harmonics ( P 1) and the discrete ordinates method (DOM) are used to calculate radiation. The radiative properties of the gases are calculated using a non-gray gas full spectrum k-distribution method and a gray method. Analysis of the effects of numerical quadrature in the DOM and its effect on computation time is performed. Results of different radiative property methods are compared with benchmark statistical narrow band (SNB) data for both cases that simulate air combustion and oxy-fuel combustion. For both cases, results of the non-gray full spectrum k-distribution method are in good agreement with the SNB data. In the case of oxy-fuel simulations with high partial pressures of carbon dioxide, use of gray method for the radiative properties may cause errors and should be avoided.

Three-dimensional source tracking in an uncertain environment

This paper develops an approach to three-dimensional source tracking in an uncertain ocean environment using a horizontal line array (HLA). The tracking algorithm combines matched-field focalization for environmental (seabed and water column) and source-bearing model parameters with the Viterbi algorithm for range-depth estimation and includes physical constraints on source velocity. The ability to track a source despite environmental uncertainty is examined using synthetic test cases for various track geometries and with varying degrees of prior information for environmental parameters. Performance is evaluated for a range of signal-to-noise ratios in terms of the probability of estimating a track within acceptable position/depth errors. The algorithm substantially outperforms tracking with poor environmental estimates and generally obtains results close to those obtained with exact environmental knowledge. The approach is also applied to measured narrowband data recorded on a bottom-moored HLA in shallow water (the Barents Sea) and shown to successfully track both a towed submerged source and a surface ship in cases where simpler tracking algorithms failed.

Three-dimensional source tracking in an uncertain environment via focalization.

This paper develops an approach to three-dimensional source tracking in an uncertain ocean environment using a horizontal line array (HLA). The tracking algorithm combines matched-field focalization for environmental (seabed and water column) and source-bearing model parameters with the VITERBI algorithm for range-depth estimation, and includes physical constraints on source velocity. The ability to track a source despite environmental uncertainty is examined using synthetic test cases for various track geometries and with varying degrees of prior information for environmental parameters. Performance is evaluated for a range of signal-to-noise ratios in terms of the probability of estimating a track within acceptable position/depth errors. The algorithm substantially outperforms tracking with poor environmental estimates, and generally obtains results close to those obtained with exact environmental knowledge. The approach is also applied to measured narrowband data recorded on a bottom-moored HLA in shallow water (the Barents Sea) and shown to successfully track both a towed submerged source and a surface ship in cases where simpler tracking algorithms failed.

Deficiency of the Massachusetts Pure Tone Noise Regulation.

The Commonwealth of Massachusetts Department of Environmental Protection (MADEP) noise regulation has two parts. The first part involves overall A‐weighted noise and requires that no source of sound be greater than 10 dB above the background noise. A second part states that no pure tones are allowed. A pure tone condition is defined by the MADEP as any octave band that is greater than the adjacent bands by 3 dB. The author was involved in community noise investigation that showed the deficiency of the pure tone requirement. A suburban community complained of bothersome noise from an industrial abutter. Noise measurements were taken by other consultants which did not register as a pure tone. The author was hired by the community group to conduct measurements on their behalf. Similar octave band measurements were taken with similar results. However, measurements with finer one‐third octave band showed significant tonal activity. When compared to commercial standards for pure tones the tonal criterion was met. Further examination of narrowband data showed why the original octave band measurements were not registering pure tone conditions. The author will present his suggestion for changes to the MADEP regulation and welcomes input from others dealing with similar tonal requirements.

Photo-interpretation and remote sensing at the Faculty of Forestry and Environmental Management, UNB

Classically, remote sensing has been used as input data for land cover mapping. Through remote sensing studies at the University of New Brunswick Faculty of Forestry and Environmental Management, broader applications have been developed. These include: 1) fuel moisture mapping using optical and thermal infrared NOAA-AVHRR and MODIS images, as well as synthetic aperture radar (SAR) images (single-polarized images from ERS-1 and RADARSAT-1 and polarimetric images from RADARSAT-2); 2) determination of plant nitrogen and chlorophyll content using narrow-band hyperspectral data; and 3) imaging system applications in the wood industry. The third type of applications include: 1) mapping of internal wood features using X-ray computer tomography images, 2) monitoring of wood deformations using digital images acquired in the visible band, and 3) use of near-infrared spectroscopy to identify and sort wood by species, colour, physical properties, and surfacing/aging history. This last technology will also be used to determine lignin, cellulose and hemi-cellulose contents of wood products for value-added applications. Key words: optical, thermal infrared, radar, fuel moisture, crop nitrogen, X-ray CT images, image correlation, wood scanning, NOAA-AVHRR, MODIS, ERS-1, RADARSAT-1, radar polarimetry, RADARSAT-2

A Photometric Survey for Lyα–HeiiDual Emitters: Searching for Population III Stars in High‐Redshift Galaxies

We present a new photometric search for high-z galaxies hosting Population III (Pop III) stars based on deep intermediate-band imaging observations obtained in the Subaru Deep Field (SDF), using Suprime-Cam on the Subaru Telescope. By combining our new data with the existing broadband and narrowband data, we searched for galaxies that emit strongly in both Lyα and He II λ1640 (dual emitters) and are promising candidates for Pop III-hosting galaxies at 3.93 z 4.01 and 4.57 z 4.65. Although we found 10 dual emitters, most of them turn out to be [O II]-[O III] dual emitters or Hβ-(Hα+[N II]) dual emitters at z < 1, as inferred from their broadband colors and from the ratio of the equivalent widths. No convincing candidate Lyα-He II dual emitter of SFRPopIII 2 M☉ yr−1 was found by our photometric search in 4.03 × 105 Mpc3 in the SDF. This result disfavors low-feedback models for Pop III star clusters and implies an upper limit on the Pop III SFR density of SFRDPopIII < 5 × 10−6 M☉ yr−1 Mpc−3. This new selection method to search for Pop III-hosting galaxies should be useful in future narrowband surveys to achieve the first observational detection of Pop III-hosting galaxies at high redshifts.

Observational Search for Population III Stars in High-Redshift Galaxies

AbstractIn this contribution we present our new photometric search for high-z galaxies hosting Population III (PopIII) stars based on deep intermediate-band imaging observations, by using Supreme-Cam on the Subaru Telescope. By combining our new data with the existing broad-band and narrow-band data in the target field, we searched for galaxies which emit strongly both in Lyα and in Heiiλ1640 (“dual emitters”) that are promising candidates for PopIII-hosting galaxies, at 4 ≲ z ≲ 5. Although we found 10 “dual emitters”, most of them turn out to be [Oii]-[Oiii] dual emitters or Hβ-Hα dual emitters at z &lt; 1, as inferred from their broad-band colors and from the ratio of the equivalent widths. No convincing candidate of Lyα-Heii dual emitter with SFRPopIII ≳ 2M⊙ yr−1 was found. This result disfavors low feedback models for PopIII star clusters, and implies an upper limit of the PopIII SFR density of SFRDPopIII &lt; 5 × 10−6M⊙ yr−1 Mpc−3. This new selection method to search for PopIII-hosting galaxies should be useful in future surveys for the first observational detection of PopIII-hosting galaxies at high redshift.

Geoacoustic uncertainties in matched‐field inversions of ship‐noise data

This paper applies geoacoustic inversion to ship‐noise data recorded on a horizontal array deployed on the seafloor in an experiment conducted by FFI in the Barents Sea. A Bayesian matched‐field inversion method is employed which quantifies geoacoustic uncertainties and allows for quantitative comparisons of results from different data sets. Estimates of sediment parameters and their uncertainties were obtained by inversions of low‐frequency narrowband data from a quiet research ship at source‐array ranges of 1‐6 km and different orientations with respect to the array, as well as from a merchant ship at ranges of 6‐8 km. Multiple, independent data segments are included in the inversion and shown to significantly reduce geoacoustic parameter uncertainties. The effect of the state of prior information on the ship track (e.g., well known or unknown) on geoacoustic information content is also examined. Estimates of the sound‐speed profile and density of sediment are compared with results from inversion of data from a towed controlled‐source, and with reference values from other geophysical data collected in the area.

Experimental confirmation of negative dispersion and Bayesian inversion of multimode propagation in a bone‐mimicking phantom

Previously we demonstrated using numerical simulations that negative dispersion observed in bone can result from the interference of two propagating modes, each of which exhibits positive dispersion, consistent with the Kramers‐Kronig predictions. [J. Acoust. Soc. Am. 120, EL55‐61 (2006)] One goal of the present study was to demonstrate this negative dispersion experimentally using the simplest example of a bone‐mimicking phantom that is capable of producing two such interfering modes. An additional goal was to establish that, with the experimental data serving as input to a Bayesian approach to the inverse problem [J. Acoust. Soc. Am. 121, EL8‐15 (2007)], reliable estimates of the underlying properties of the bone‐mimicking phantom could be obtained from the measured signals. The phantom consisted of a flat and parallel PlexiglasTM plate into which a step discontinuity was milled. The phase velocity and attenuation coefficient (3 to 7 MHz) of the phantom were measured with a 0.25‐inch piezoelectric receiver and calculated using both broadband and narrowband data. Negative dispersion was observed at specific spatial locations near the step where the attenuation coefficient rose approximately linearly with frequency. Results demonstrate that interference between modes can result in negative dispersion and that Bayesian inversion can yield underlying material properties.

Negative dispersion in bone: The role of interference in measurements of the apparent phase velocity of two temporally overlapping signals

In this study the attenuation coefficient and dispersion (frequency dependence of phase velocity) are measured using a phase sensitive (piezoelectric) receiver in a phantom in which two temporally overlapping signals are detected, analogous to the fast and slow waves typically found in measurements of cancellous bone. The phantom consisted of a flat and parallel Plexiglas plate into which a step discontinuity was milled. The phase velocity and attenuation coefficient of the plate were measured using both broadband and narrowband data and were calculated using standard magnitude and phase spectroscopy techniques. The observed frequency dependence of the phase velocity and attenuation coefficient exhibit significant changes in their frequency dependences as the interrogating ultrasonic field is translated across the step discontinuity of the plate. Negative dispersion is observed at specific spatial locations of the plate at which the attenuation coefficient rises linearly with frequency, a behavior analogous to that of bone measurements reported in the literature. For all sites investigated, broadband and narrowband data (3-7 MHz) demonstrate excellent consistency. Evidence suggests that the interference between the two signals simultaneously reaching the phase sensitive piezoelectric receiver is responsible for this negative dispersion.

Spatially Explicit Estimation of Leaf Area Index Using EO-1 Hyperion and Landsat ETM+ Data: Implications of Spectral Bandwidth and Shortwave Infrared Data on Prediction Accuracy in a Tropical Montane Environment

This study evaluated the utility of narrowband (EO-1 Hyperion) and broadband (Landsat ETM+) remote sensing data for the estimation of leaf area index (LAI) in a tropical environment in Sulawesi, Indonesia. LAI was inferred from canopy gap fraction measurements taken in natural tropical forest and cocoa plantations. Single and multiple spectral bands and spectral indices were used as predictor variables in reduced major axis (RMA) and ordinary least squares (OLS) regression models. The predictive power of most regression models was notably higher when employing narrowband data instead of broadband data. Highly significant relationships between LAI and spectral reflectance were observed near the red-edge region and in most shortwave infrared (SWIR) bands. In contrast to most near-infrared (NIR) narrow bands, the correlation between SWIR reflectance and LAI was not confounded when including both vegetation types and did not suffer from saturation. The results demonstrate that leaf area index of a challenging tropical environment can be estimated with satisfactory accuracy from hyperspectral remote sensing data.

An investigation of the capabilities of a short hydrophone array towed by an ocean glider

During the Shallow Water Experiment (SW06) a Webb Slocum glider, deployed by Rutgers University, demonstrated that gliders are promising vehicles for towing short acoustic arrays. The gliders saw-tooth trajectory allows for sampling the water column at varying depths and ranges. Further, the glider provides a low-speed platform, allowing for a flow-noise free towed array, which is ideal for the processing of low level signals. One attractive application for glider-towed arrays is target tracking. By using the passive synthetic aperture effect, coupled with a near-field model for the signal, the coordinates of an acoustic source can be estimated using a Kalman filter, but without the necessity of the maneuver normally required by bearings-only tracking. This is possible since the large aperture traced out by the glider permits wavefront curvature to be exploited for range estimation. Using synthetic narrowband data, it is shown that the range and bearing of a low-level acoustic source can be estimated without changing the gliders course. The algorithm is based on an Unscented Kalman Filter. Also, an approach for the broadband problem is outlined. [Work sponsored by the Office of Naval Research.]

Bayesian geoacoustic inversion of ship-noise data from a bottom-moored horizontal line array

This paper presents results from matched-field geoacoustic inversion of low-frequency (40–150 Hz) ship-noise data recorded on a horizontal array deployed at the seafloor. Data are taken from an experiment conducted by FFI in shallow waters of the Barents Sea. Estimates of sediment parameters were obtained by inversions of narrowband data from a relatively quiet surface ship at source-array ranges of 1–6 km. The fast Gibbs sampler was used to estimate posterior probability densities of model parameters. Estimates of sound speed and density of quaternary sediment are compared with results from inversion of data from a towed source collected along the same track, and with reference values from other geophysical data collected in the area.

Out-of-core and compressed level set methods

This article presents a generic framework for the representation and deformation of level set surfaces at extreme resolutions. The framework is composed of two modules that each utilize optimized and application specific algorithms: 1) A fastout-of-coredata management scheme that allows for resolutions of the deforming geometry limited only by the available disk space as opposed to memory, and 2) compact and fastcompressionstrategies that reduce both offline storage requirements and online memory footprints during simulation. Out-of-core and compression techniques have been applied to a wide range of computer graphics problems in recent years, but this article is the first to apply it in the context of level set and fluidsimulations. Our framework is generic and flexible in the sense that the two modules can transparently be integrated, separately or in any combination, into existing level set and fluid simulation software based on recently proposed narrow band data structures like the DT-Grid of Nielsen and Museth [2006] and the H-RLE of Houston et al [2006]. The framework can be applied to narrow band signed distances, fluid velocities, scalar fields, particle properties as well as standard graphics attributes like colors, texture coordinates, normals, displacements etc. In fact, our framework is applicable to a large body of computer graphics problems that involve sequential or random access to very large co-dimension one (level set) and zero (e.g. fluid) data sets. We demonstrate this with several applications, including fluid simulations interacting with large boundaries (≈ 15003), surface deformations (≈ 20483), the solution of partial differential equations on large surfaces (≈ 40963) and mesh-to-level set scan conversions of resolutions up to ≈ 350003(7 billion voxels in the narrow band). Our out-of-core framework is shown to be several times faster than current state-of-the-art level set data structures relying on OS paging. In particular we show sustained throughput (grid points/sec) for gigabyte sized level sets as high as 65% of state-of-the-art throughput for in-core simulations. We also demonstrate that our compression techniques out-perform state-of-the-art compression algorithms for narrow bands.

Using in‐situ measurements to evaluate the new RapidEye™ satellite series for prediction of wheat nitrogen status

This study assessed whether vegetation indices derived from broadband RapidEye™ data containing the red edge region (690–730 nm) equal those computed from narrow band data in predicting nitrogen (N) status of spring wheat (Triticum aestivum L.). Various single and combined indices were computed from in‐situ spectroradiometer data and simulated RapidEye™ data. A new, combined index derived from the Modified Chlorophyll Absorption Ratio Index (MCARI) and the second Modified Triangular Vegetation Index (MTVI2) in ratio obtained the best regression relationships with chlorophyll meter values (Minolta Soil Plant Analysis Development (SPAD) 502 chlorophyll meter) and flag leaf N. For SPAD, r 2 values ranged from 0.45 to 0.69 (p<0.01) for narrow bands and from 0.35 and 0.77 (p<0.01) for broad bands. For leaf N, r 2 values ranged from 0.41 to 0.68 (p<0.01) for narrow bands and 0.37 to 0.56 (p<0.01) for broad bands. These results are sufficiently promising to suggest that MCARI/MTVI2 employing broadband RapidEye™ data is useful for predicting wheat N status.

Brief summary on the status of my 2007 activities

Tashkent International Heliophysical Year (IHY) station is a member of Atmospheric Weather Electromagnetic System for Observation, Modeling and Education (AWESOME) network being operated globally to study the ionosphere and the magnetosphere with the help of electromagnetic waves in Very Low Frequency (VLF) band. Regular monitoring of the D- and F-layers of ionosphere over Central Asia territory is being performed on the permanent basis starting year 2008. We have studied VLF amplitude anomalies related to the EQs occurred in 2008–2009 years with magnitude more than 5 on the path way from the VLF transmitters to the Tashkent station assuming that propagation of VLF ground-based transmitters signals can be perturbed by EQ preparation detectable from the ground-based measurements in the VLF bands. For analyzing narrowband data we have used the nighttime fluctuation (NF) method paying attention to the data obtained during the local nighttime (20:00 LT–04:00 LT) in Tashkent where the VLF receiver is operating. The mean nighttime amplitude (or trend) and nighttime fluctuation are found to increase significantly before the EQ occurred on the path way from the transmitters to the receiver. The obtained results have revealed an agreement with VLF amplitude anomalies observed in Tashkent VLF station during the strong EQs occurred on the path way from the transmitters to the receiver. Some results are presented to show the probing potentiality of VLF waves to predict short term EQs with high magnitude.

Image-Processing Techniques for the Creation of Presentation-Quality Astronomical Images

The quality of modern astronomical data and the agility of current image-processing software enable the visualization of data in a way that exceeds the traditional definition of an astronomical image. Two developments in particular have led to a fundamental change in how astronomical images can be assembled. First, the availability of high-quality multiwavelength and narrowband data allow for images that do not correspond to the wavelength sensitivity of the human eye, thereby introducing ambiguity in the usage and interpretation of color. Second, many image-processing software packages now use a layering metaphor that allows for any number of astronomical data sets to be combined into a color image. With this technique, images with as many as eight data sets have been produced. Each data set is intensity-scaled and colorized independently, creating an immense parameter space that can be used to assemble the image. Since such images are intended for data visualization, scaling and color schemes must be chosen that best illustrate the science. A practical guide is presented on how to use the layering metaphor to generate publication-ready astronomical images from as many data sets as desired. A methodology is also given on how to use intensity scaling, color, and composition to create contrasts in an image that highlight the scientific detail. Examples of image creation are discussed.