A Bernoulli–Gaussian Binary Inversion Method for High-Frequency Electromagnetic Imaging of Metallic Reflectors

2020 ◽  
Vol 68 (4) ◽  
pp. 3184-3193 ◽  
Author(s):  
Fang-Fang Wang ◽  
Qing Huo Liu
Keyword(s):  
High Frequency ◽  
Inversion Method ◽  
Electromagnetic Imaging

scholarly journals Estimates of European emissions of methyl chloroform using a Bayesian inversion method

2014 ◽  
Vol 14 (18) ◽  
pp. 9755-9770 ◽  
Author(s):  
M. Maione ◽  
F. Graziosi ◽  
J. Arduini ◽  
F. Furlani ◽  
U. Giostra ◽  
...  
Keyword(s):  
Point Source ◽  
High Frequency ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Source Analysis ◽  
Bayesian Inversion ◽  
Inversion Method ◽  
Data Set ◽  
Methyl Chloroform

Abstract. Methyl chloroform (MCF) is a man-made chlorinated solvent contributing to the destruction of stratospheric ozone and is controlled under the "Montreal Protocol on Substances that Deplete the Ozone Layer" and its amendments, which called for its phase-out in 1996 in developed countries and 2015 in developing countries. Long-term, high-frequency observations of MCF carried out at three European sites show a constant decline in the background mixing ratios of MCF. However, we observe persistent non-negligible mixing ratio enhancements of MCF in pollution episodes, suggesting unexpectedly high ongoing emissions in Europe. In order to identify the source regions and to give an estimate of the magnitude of such emissions, we have used a Bayesian inversion method and a point source analysis, based on high-frequency long-term observations at the three European sites. The inversion identified southeastern France (SEF) as a region with enhanced MCF emissions. This estimate was confirmed by the point source analysis. We performed this analysis using an 11-year data set, from January 2002 to December 2012. Overall, emissions estimated for the European study domain decreased nearly exponentially from 1.1 Gg yr−1 in 2002 to 0.32 Gg yr−1 in 2012, of which the estimated emissions from the SEF region accounted for 0.49 Gg yr−1 in 2002 and 0.20 Gg yr−1 in 2012. The European estimates are a significant fraction of the total semi-hemisphere (30–90° N) emissions, contributing a minimum of 9.8% in 2004 and a maximum of 33.7% in 2011, of which on average 50% are from the SEF region. On the global scale, the SEF region is thus responsible for a minimum of 2.6% (in 2003) and a maximum of 10.3% (in 2009) of the global MCF emissions.

Spatial distribution of high-frequency energy radiation on the fault of the 1995 Hyogo-Ken Nanbu, Japan, earthquake (MW 6.9) on the basis of the seismogram envelope inversion

1999 ◽  
Vol 89 (1) ◽  
pp. 22-35 ◽  
Author(s):  
Hisashi Nakahara ◽  
Haruo Sato ◽  
Masakazu Ohtake ◽  
Takeshi Nishimura
Keyword(s):  
Spatial Distribution ◽  
Wave Energy ◽  
High Frequency ◽  
Fault Plane ◽  
Time Window ◽  
Source Region ◽  
Inversion Method ◽  
S Wave ◽  
Energy Radiation ◽  
Initial Rupture

Abstract We studied the generation and propagation of high-frequency (above 1 Hz) S-wave energy from the 1995 Hyogo-Ken Nanbu (Kobe), Japan, earthquake (MW 6.9) by analyzing seismogram envelopes of the mainshock and aftershocks. We first investigated the propagation characteristics of high-frequency S-wave energy in the heterogeneous lithosphere around the source region. By applying the multiple lapse time window analysis method to aftershock records, we estimated two parameters that quantitatively characterize the heterogeneity of the medium: the total scattering coefficient and the intrinsic absorption of the medium for S waves. Observed envelopes of aftershocks were well reproduced by the envelope Green functions synthesized based on the radiative transfer theory with the obtained parameters. Next, we applied the envelope inversion method to 13 strong-motion records of the mainshock. We divided the mainshock fault plane of 49 × 21 km into 21 subfaults of 7 × 7 km square and estimated the spatial distribution of the high-frequency energy radiation on that plane. The average constant rupture velocity and the duration of energy radiation for each subfault were determined by grid searching to be 3.0 km/sec and 5.0 sec, respectively. Energy radiated from the whole fault plane was estimated as 4.9 × 1014 J for 1 to 2 Hz, 3.3 × 1014 J for 2 to 4 Hz, 1.5 × 1014 J for 4 to 8 Hz, 8.9 × 1012 J for 8 to 16 Hz, and 9.8 × 1014 J in all four frequency bands. We found that strong energy was mainly radiated from three regions on the mainshock fault plane: around the initial rupture point, near the surface at Awaji Island, and a shallow portion beneath Kobe. We interpret that energetic portions were associated with rupture acceleration, a fault surface break, and rupture termination, respectively.

scholarly journals European emissions of HCFC-22 based on eleven years of high frequency atmospheric measurements and a Bayesian inversion method

2015 ◽  
Vol 112 ◽  
pp. 196-207 ◽  
Author(s):  
F. Graziosi ◽  
J. Arduini ◽  
F. Furlani ◽  
U. Giostra ◽  
L.J.M. Kuijpers ◽  
...  
Keyword(s):  
High Frequency ◽  
Bayesian Inversion ◽  
Inversion Method ◽  
Atmospheric Measurements

Imaging a hydrate-related cold vent offshore Vancouver Island from deep-towed multichannel seismic data

Geophysics ◽  
2009 ◽  
Vol 74 (2) ◽  
pp. B23-B36 ◽  
Author(s):  
Tao He ◽  
George D. Spence ◽  
Warren T. Wood ◽  
Michael Riedel ◽  
Roy D. Hyndman
Keyword(s):  
High Frequency ◽  
Seismic Velocity ◽  
Vancouver Island ◽  
Inversion Method ◽  
Acoustic Image ◽  
Near Surface ◽  
High Reflectivity ◽  
Redundant Data ◽  
Integrated Ocean Drilling Program ◽  
Cold Vent

The Bullseye vent, an approximately [Formula: see text]-diameter deep-sea, hydrate-related cold vent on the midslope offshore Vancouver Island, was imaged in a high-resolution multichannel survey by the Deep-towed Acoustics and Geophysics System (DTAGS) The structure was drilled by the Integrated Ocean Drilling Program at site U1328. Towed about [Formula: see text] above the seafloor, the high-frequency [Formula: see text] DTAGS system provides a high vertical and lateral resolution image. The major problems in imaging with DTAGS data are nonlinear variations of the source depths and receiver locations. The high-frequency, short-wavelength data require very accurate positioning of source and receivers for stacking and velocity analyses. New routines were developed for optimal processing, including receiver cable geometry estimation from node depths, direct arrivals and sea-surface reflections using a genetic algorithm inversion method, and acoustic image stitching based on relative source positioning bycrosscorrelating redundant data between two adjacent shots. Semblance seismic velocity analysis was applied to common-reflection-point bins of the corrected data. The processed images resolve many subvertical zones of low seismic reflectivity and fine details of subseafloor sediment structure. At the Bullseye vent, where a [Formula: see text]-thick near-surface massive hydrate layer was drilled at U1328, the images resolve the upper part of the layer as a dipping high-reflectivity zone, likely corresponding to a fracture zone. Velocity analyses were not possible in the vent structure but were obtained [Formula: see text] to either side. Normal velocities are in the upper [Formula: see text], but over the interval from [Formula: see text] below the seafloor at the northeast side, the velocities are higher than the average normal slope sediment velocity of approximately [Formula: see text]. These high velocities are probably related to the high reflectivity zone and to the bottom portion of the massive hydrate detected by resistivity measurements in the upper [Formula: see text] at U1328.

Stochastic inversion of prestack seismic data using fractal-based initial models

Geophysics ◽  
2010 ◽  
Vol 75 (3) ◽  
pp. R47-R59 ◽  
Author(s):  
R. P. Srivastava ◽  
M. K. Sen
Keyword(s):  
Seismic Data ◽  
High Frequency ◽  
Fractal Theory ◽  
Well Logs ◽  
Inversion Method ◽  
Frequency Variation ◽  
Well Log ◽  
Statistical Parameters ◽  
Stochastic Inversion ◽  
Frequency Variations

In general, inversion algorithms rely on good starting models to produce realistic earth models. A new method, based on a fractional Gaussian distribution derived from the statistical parameters of available well logs to generate realistic initial models, uses fractal theory to generate these models. When such fractal-based initial models estimate P- and S-impedance profiles in a prestack stochastic inversion of seismic angle gathers, very fast simulated annealing — a global optimization method — finds the minimum of an objective function that minimizes data misfit and honors the statistics derived from well logs. The new stochastic inversion method addresses frequencies missing because of band limitation of the wavelet; it combines the low- and high-frequency variation from well logs with seismic data. This method has been implemented successfully using real prestack seismic data, and results have been compared with deterministic inversion. Models derived by a deterministic inversion are devoid of high-frequency variations in the well log; however, models derived by stochastic inversion reveal high-frequency variations that are consistent with seismic and well-log data.

scholarly journals 3D Sonoembryology

2011 ◽  
Vol 5 (1) ◽  
pp. 7-15
Keyword(s):  
High Resolution ◽  
Gestational Age ◽  
Congenital Anomalies ◽  
High Frequency ◽  
Cleft Lip ◽  
Three Dimensional ◽  
Staging System ◽  
Inversion Method ◽  
Crown Rump Length ◽  
Transvaginal Approach

ABSTRACT After the introduction of high-frequency transvaginal transducers in clinical obstetrics, the term ‘sonoembryology’ was first coined in 1990.1 Three-dimensional sonography performed with a transvaginal approach has expanded the depth of inquiry and allowed threedimensional sonoembryology. Transvaginal approach combined with high frequency (12 MHz) and a harmonic phase inversion method can provide us images with high quality and high resolution demonstrating detailed embryonal structures, including normal development of embryos and fetuses, and many congenital abnormalities, such as conjoined twin from 9 weeks, vertebral abnormality from 9 weeks, cleft lip/palate from 12 weeks, congenital cataract from 14 weeks, limb abnormality from 11 weeks, thoracoabdominal abnormality from 12 weeks of gestation. It is possible that by developing 3D neurosonoembryology imaging in utero, current fetal staging (which uses gestational age based on last menstrual period or crown-rump length measurement) may change into a ‘morphological staging system’, such as the Carnegie staging system, which has been central to embryology. A novel imaging technique of high-resolution transvaginal 3D sonography is illustrated in the definition of normal embryonic anatomy as well as in the identification of many congenital anomalies. They allow extending the detection of anatomical congenital anomalies to an earlier gestational age.

scholarly journals Estimates of European emissions of methyl chloroform using a Bayesian inversion method

2014 ◽  
Vol 14 (6) ◽  
pp. 8209-8256 ◽  
Author(s):  
M. Maione ◽  
F. Graziosi ◽  
J. Arduini ◽  
F. Furlani ◽  
U. Giostra ◽  
...  
Keyword(s):  
Point Source ◽  
High Frequency ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Source Analysis ◽  
Bayesian Inversion ◽  
Inversion Method ◽  
Data Set ◽  
Methyl Chloroform

Abstract. Methyl chloroform (MCF) is a man-made chlorinated solvent contributing to the destruction of stratospheric ozone and is controlled under the Montreal Protocol on Substances that Deplete the Ozone Layer. Long-term, high-frequency observations of MCF carried out at three European sites show a constant decline of the background mixing ratios of MCF. However, we observe persistent non-negligible mixing ratio enhancements of MCF in pollution episodes suggesting unexpectedly high ongoing emissions in Europe. In order to identify the source regions and to give an estimate of the magnitude of such emissions, we have used a Bayesian inversion method and a point source analysis, based on high-frequency long-term observations at the three European sites. The inversion identified south-eastern France (SEF) as a region with enhanced MCF emissions. This estimate was confirmed by the point source analysis. We performed this analysis using an eleven-year data set, from January 2002 to December 2012. Overall emissions estimated for the European study domain decreased nearly exponentially from 1.1 Gg yr−1 in 2002 to 0.32 Gg yr−1 in 2012, of which the estimated emissions from the SEF region accounted for 0.49 Gg yr−1 in 2002 and 0.20 Gg yr−1 in 2012. The European estimates are a significant fraction of the total semi-hemisphere (30–90° N) emissions, contributing a minimum of 9.8% in 2004 and a maximum of 33.7% in 2011, of which on average 50% are from the SEF region. On the global scale, the SEF region is thus responsible from a minimum of 2.6% (in 2003) to a maximum of 10.3% (in 2009) of the global MCF emissions.

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