Azimuth Data Research Articles

Real-time Dangerous Driving Behavior Analysis Utilizing the Digital Tachograph and Smartphone

In this paper, we propose the assistance method to enable safe driving through analysis of dangerous driving behavior using real-time alarm by vehicle speed, azimuth data and smartphone. For this method, smartphone is receiving driving data from digital tachograph using communication. Safe driving habit is a very important issue to commercial vehicle because that driver's long time driving than other vehicle type driver. Existing methods are very inefficient to improve immediately dangerous driving habits during driving because proceed driving behavior analysis after the vehicle operation. We propose the new safe driving assistance method that can prevent traffic accidents by real-time and improve the driver's wrong driving habits through real-time dangerous driving behavior analysis and notification the result to the driver. We have confirmed that the method in this paper will help to improve driving habits and can be applied through the proposed method implementation and simulation experiment.

A Realization of Signal-Model-Based SAR Imaging via Atomic Decomposition

A signal-model-based SAR image formation algorithm is proposed in this paper. A model is used to describe the received signal, and each scatterer can be characterized by a set of its parameters. Two parameter estimation methods via atomic decomposition are presented: (1) applying 1-D matching pursuit to azimuthal projection data; (2) applying 2-D matching pursuit to raw data. The estimated parameters are mapped to form a SAR image, and the mapping procedure can be implemented under application guidelines. This algorithm requires no prior information about the relative motion between the platform and the target. The Cramer-Rao bounds of parameter estimation are derived, and the root mean square errors of the estimates are close to the bounds. Experimental results are given to validate the algorithm and indicate its potential applications.

Two-Dimensional Imaging Algorithm Based on Linear Prognosis for Space Target in Bistatic ISAR System

In bistatic inverse synthetic aperture radar (Bi-ISAR) system, its image resolution is lower than monostatic ISAR system. In order to solve this problem, the linear prognosis algorithm is adopted in the imaging process and the imaging algorithm based on linear prognosis is proposed. Space target Bi-ISAR imaging is taken as example in the research. The one-dimensional range profile is created through pulse compression method. Before the azimuth compression, burg entropy maximum algorithm in Levions recursive method is used to estimate the prognosis coefficients and the azimuth echo data. Then Fourier transformation is used to compress the azimuth data in order to get the high resolution azimuth image. This imaging method can obtain the two-dimensional image with the resolution equal to the monostatic ISAR or even higher than it. Simulation experiments have verified the effectiveness and availability of the algorithm.

Determination and identification of focal mechanism solutions for Himalayan earthquakes from waveform inversion employing ISOLA software

ISOLA software has been used to determine moment tensor solutions by using the single-station three-component seismogram data. This will be useful and worthwhile for analysis of the earthquakes occurred in Himalayan region, where well azimuthal coverage data are not available. Two earthquakes occurred in Garhwal Himalaya on 21 September 2009 (Mw 5.2) near Uttarkashi and on 3 May 2010 (Mw 4.1) near Ghansali with known fault plane solutions from polarity inversion have been used to identify and verify the obtained moment tensor solutions from waveform inversion. The focal mechanism solutions of 21 September 2009 and 3 May 2010 estimated by two different independent schemes, i.e. single- and multiple-station waveform inversion and polarity inversion, have been found in agreement. Also the magnitude estimated by waveform inversion agrees with the report by various agencies. The inversion has been performed by using maximum azimuthal coverage data as well as using only single-station data. The frequency bands used for inversion of 21 September 2009 and 3 May 2010 are 0.02–0.11 and 0.08–0.20 Hz, respectively. These bands correspond to the maximum signal-to-noise ratio. The solutions estimated by polarity inversion, maximum-station data and single-station data have almost similar focal mechanism parameters. This infers that if an accurate crustal velocity structure, hypocentre location and a proper frequency band have been used, then moment tensor solutions can be estimated by single-station waveform data.

AVAZ inversion for fracture weakness parameters based on the rock physics model

Subsurface fractures within many carbonates and unconventional resources play an important role in the storage and movement of fluid. The more reliably the detection of fractures could be performed, the more finely the reservoir description could be made. In this paper, we aim to propose a method which uses two important tools, a fractured anisotropic rock physics effective model and AVAZ (amplitude versus incident and azimuthal angle) inversion, to predict fractures from azimuthal seismic data. We assume that the rock, which contains one or more sets of vertical or sub-vertical fractures, shows transverse isotropy with a horizontal axis of symmetry (HTI). Firstly, we develop one improved fractured anisotropic rock physics effective model. Using this model, we estimate P-wave velocity, S-wave velocity and fracture weaknesses from well-logging data. Then the method is proposed to predict fractures from azimuthal seismic data based on AVAZ inversion, and well A is used to verify the reliability of the improved rock physics effective model. Results show that the estimated results are consistent with the real log value, and the variation of fracture weaknesses may detect the locations of fractures. The damped least squares method, which uses the estimated results as initial constraints during the inversion, is more stable. Tests on synthetic data show that fracture weaknesses parameters are still estimated reasonably with moderate noise. A test on real data shows that the estimated results are in good agreement with the drilling.

Enhanced subsurface illumination from separated wavefield imaging

Shaoping Lu, Dan Whitmore, Alejandro Valenciano and Nizar Chemingui present applications of separated wavefield imaging to a deepwater wide-azimuth survey in the Gulf of Mexico and to a narrow azimuth data set from offshore Malaysia.

An iterative approach to updating velocities beneath postsalt anomalies and its impact on presalt imaging

Complex geology and deepwater presalt targets offshore Brazil lend themselves to seismic imaging challenges. The postsalt sections of the Santos and Campos Basins also featured thin-bed, high-impedance layers of volcanic material and other shallow velocity anomalies. These features were often near the top of salt (TOS) and produced areas of poor presalt focusing. Because accurately modeling the postsalt was imperative for imaging the presalt, we developed a new workflow for velocity model updating. Where previous top-down methods have failed, our method embraced the challenges of imaging beneath the volcanics by incorporating additional presalt information into the updates. Our method is interpretation-dependent but provides a robust and reliable workflow for updating the postsalt velocity model in the presence of complex geology. Using a narrow azimuth data set acquired with variable-depth streamers, we evaluated the effectiveness of our iterative workflow. The result was improved presalt imaging.

Effect of azimuthal coverage of an earthquake on moment tensor solutions estimated by waveform inversion

The purposes of this seismological investigation are to understand and describe the effect of decrease in the azimuthal coverage of an earthquake on moment tensor solution estimated by waveform inversion. It will be very useful and worthwhile as mostly seismological networks are sparse and in case when only one or two station data are available. In this work, we have used two moderate earthquakes, 21 September 2009 (near Uttarakashi) and 3 May 2010 (near Ghansali). The waveform inversion has been carried using ISOLA software. The moment tensor is first estimated by using all station data and then by removing the stations so that the azimuthal coverage changes. The results show that strike of both nodal planes is varying with the change in azimuthal coverage. However, the slip and dip of both nodal planes remain quite stable against the variation in azimuthal coverage for these two earthquakes analyzed. The effect of decrease in the azimuthal coverage showed increase in double-couple percentage (DC %) and decrease in compensated linear vector decomposition (CLVD %). The other focal parameters such as T-axis azimuth, P-axis azimuth, T-axis plunge, and P-axis plunge have been found stable against the variation in azimuth coverage. The study also demonstrates that the moment tensor solutions obtained from waveform inversion using single station are almost similar to those estimated using maximum azimuthal coverage data and by polarity inversion.

A Bayesian framework for fracture characterization from surface seismic data

We describe a methodology for quantitatively characterizing the fractured nature of a hydrocarbon or geothermal reservoir from surface seismic data under a Bayesian inference framework. The method combines different kinds of measurements of fracture properties to find a best-fitting model while providing estimates of the uncertainty of model parameters. Fractures provide pathways for fluid flow in a reservoir, and hence, knowledge about a reservoir's fractured nature can be used to enhance production from the reservoir. The fracture properties of interest in this study (to be inferred) are fracture orientation and excess compliance, where each of these properties are assumed to vary spatially over a 2-D horizontal grid which is assumed to represent the top of a reservoir. The Bayesian framework in which the inference problem is cast has the key benefits of (1) utilization of a prior model that allows geological information to be incorporated, (2) providing a straightforward means of incorporating all measurements (across the 2-D spatial grid) into the estimates at each gridpoint, (3) allowing different types of measurements to be combined under a single inference procedure and (4) providing a measure of uncertainty in the estimates. The observed data are taken from a 2-D array of surface seismic receivers responding to an array of surface sources. Well understood features from the seismic traces are extracted and treated as the observed data, namely the P-wave reflection amplitude variation with acquisition azimuth and offset (amplitude versus azimuth data) and fracture transfer function (FTF) data. Amplitude versus azimuth data are known to be more sensitive to fracture properties when the fracture spacing is significantly smaller than the seismic wavelength, whereas FTF data are more sensitive to fracture properties when the fracture spacing is on the order of the seismic wavelength. Combining these two measurements has the benefit of allowing inferences to be made about fracture properties over a larger range of fracture spacing than otherwise attainable. Geophysical forward models for the measurements are used to arrive at likelihood models for the data. The prior distribution for the fracture variables is obtained by defining a Markov random field over the lateral 2-D grid where we wish to obtain fracture properties, where this method for defining the prior has the added benefit of allowing for non-stationarity in the resulting model covariance. The fracture variables are then inferred by application of loopy belief propagation to yield approximations for the posterior marginal distributions of the fracture properties, as well as the maximum a posteriori and Bayes least-squares (posterior mean) estimates of these properties. Verification of the inference procedure is performed using a synthetic data set, where the estimates obtained are shown to be at or near ground truth for the full range of fracture spacings for fracture orientation and at low fracture spacings for excess compliance estimates.

Initial-state bremsstrahlung versus final-state hydrodynamic sources of azimuthal harmonics in p+A at RHIC and LHC

Recent pT<2~GeV azimuthal correlation data from the Beam Energy Scan (BES) and D+Au runs at RHIC/BNL and, especially, the surprising similarity of azimuthal $v_n\{2m\}(p_T)$ ``transeverse flow'' harmonics in $p+Pb$ and $Pb+Pb$ at LHC have challenged the uniqueness of local equilibrium ``perfect fluid'' interpretations of those data. We report results at QM14 on azimuthal harmonics associated with initial-state non-abelian ``wave interference'' effects predicted by perturbative QCD gluon bremsstrahlung and sourced by Color Scintillation Arrays (CSA) of color antennas. CSA are naturally identified with multiple projectile and target beam jets produced in inelastic p+A reactions. We find a remarkable similarity between azimuthal harmonics sourced by initial state CSA and those predicted with final state perfect fluid models of high energy p+A reactions. The question of which mechanism dominates in $p+A$ and $A+A$ remains open at this time.

Full-Aperture SAR Data Focusing in the Spaceborne Squinted Sliding-Spotlight Mode

This paper analyzes the signal properties of spaceborne squinted sliding-spotlight synthetic aperture radar (SAR). Both the squint angle and the azimuth beam steering during the whole acquisition interval will lead to the Doppler spectrum back-folding. According to the special signal properties of this mode, a new full-aperture focusing approach, which includes three major processing steps, is proposed. In this approach, the first processing step introduces an azimuth convolution and azimuth data mosaic to resolve the azimuth spectral folding phenomenon by generalizing the existing two-step focusing technique for conventional sliding-spotlight SAR data focusing. Afterward, the modified range migration algorithm is adopted to process the resulting raw data. As the azimuth time duration of the raw data is obviously reduced in the first processing step, the obtained SAR image may be back-folded in azimuth. The final azimuth postfiltering step is to resolve the possible aliased SAR image without any azimuth data extension. The proposed full-aperture focusing processor is efficient since only a limited azimuth data extension is required to resolve the back-folded Doppler spectrum and SAR image. Imaging results on simulated raw data validate the proposed imaging approach.

A comparisonal study in the context of seismic fracture characterization based on effective stiffness and compliance methods

The use of rock physics modeling in seismic fracture characterization offers a relative advantage of reducing the number of unknown parameters during seismic inversion. This advantage can be used more constructively if the chosen rock physics model is able to relate the parameters of fractures to the effective elastic constants and makes much more physical sense. We have investigated the predictions of commonly used rock physics models (T-matrix, Hudson’s model, and non-interacting approximation) for fractured porous media within the context of seismic fracture characterization. Our reservoir model consists of a single set of aligned vertical fractures making a medium of horizontally transversely isotropic (HTI) symmetry. Seismic amplitude versus angle and azimuth (AVAZ) data was computed in the form of reflection coefficients using Ruger’s approximation. A Bayesian inversion method is then applied to seismic AVAZ data to estimate the fracture parameters and uncertainty involved in estimates. Our forward numerical experiments suggest that the predictions of non-interacting approximation (NIA) approach and T-matrix approach are equivalent to each other at very small fracture densities (<0.01), while predictions can be very different at higher fracture densities depending on the choice of aspect ratios. The predictions of NIA and T-matrix approach become same when the effect of interactions cancel at higher fracture densities, but T-matrix predictions make much more physical sense when fractures are degenerated to spherical pores. Hudson’s and T-matrix model give exactly the same predictions to the first order in fracture density, while the predictions of second-order Hudson’s model give an increasing moduli with an increasing fracture density making no physical sense. From inverse numerical experiments, NIA approach is unable to recover true fracture density and the peak of marginal distribution is always shifted towards the right of the true value. The choice of different rock physics models does not affect the estimation of azimuthal fracture orientation, and it can always be recovered with small uncertainty. It is much safer to use an interacting approach like T-matrix based on above findings within the context of seismic fracture characterization.

Data Fusion Algorithm Research Based on Multi Scout Radar Networking

Considering the shortcoming of low measurement precision of single scout radar in battlefield, this paper advances the scheme of multi scout radar networking. Aiming at the core problem of networking data fusion of multi scout radars, this paper conducts research and advances data fusion algorithm based on polar coordinate system. This paper provides the realization flow of data fusion algorithm and pays more attention to the problem of coordinate conversion, error calculation, weight determination and data synthesis based on weight, and advances solution. Finally, taking five radars networking for example, conducts simulation experiment and result analysis, and the results shows that whether the fusion precision of distance data or the azimuth data all has greater improvement than measurement data.

Fracture parameter inversion for Marcellus Shale

We inverted P-wave amplitude variation with offset and azimuth (AVOAz) data from the Marcellus Shale to obtain fracture parameters that can fully describe the elastic behavior of fractured rocks with overall symmetry of orthorhombic or monoclinic. AVOAz data from two interfaces, (1) the upper interface between top Marcellus and Stafford limestone and (2) the lower interface between base Marcellus and Onondaga limestone, were used for inversion. To check the validity of our inversion results, fracture parameters for the Marcellus Shale were inverted for each interface using Monte Carlo simulation to include uncertainty in our a priori information, i.e., elastic properties of unfractured rocks that are assumed to be known from well logs. Inversion results appeared robust with respect to uncertainties and converge to the same values for the two inversions. Our results were also consistent with singular value decomposition analysis (resolution matrix).

Investigation on Full-Aperture Multichannel Azimuth Data Processing in TOPS

The novel displaced phase center antenna (DPCA) azimuth multichannel technique is well suited to improve the coarser azimuth resolution of the terrain observation by progressive scans (TOPS) mode for a fixed total receive antenna length. However, both the azimuth multichannel nonuniform sampling and the aliased Doppler spectrum in TOPS raise the azimuth data processing difficulty. This letter proposes an innovative full-aperture processing approach, which adds an azimuth derotation step for each azimuth channel before azimuth multichannel data reconstruction and utilizes the prefiltering operation in the two-step focusing technique to resolve both azimuth ambiguity problems caused by the DPCA technique and azimuth beam progressive scanning. In addition to presenting the proposed azimuth preprocessing approach, the impact of the approach on the azimuth ambiguity-to-signal ratio is analyzed in detail. Simulation results validate the proposed multichannel processing approach for the TOPS mode.

New Software for Processing of LWD Extradeep Resistivity and Azimuthal Resistivity Data

Summary In petroleum exploration, reservoir navigation is used for reaching a productive reservoir and placing the borehole optimally inside the reservoir to maximize production. For proper well placement, it is necessary to calculate in real-time the parameters of the formation we are drilling in and the parameters of formations we are approaching. On the basis of these results, a decision to change the direction of drilling could be made. Modern logging-while-drilling (LWD) extra-deep and azimuthal resistivity tools acquire multicomponent, multispacing, and multifrequency data that provide sufficient information for resolving the surrounding formation parameters. These tools are generally used for reservoir navigation and real-time formation evaluation. However, real-time interpretation software is very often based on simplified resistivity models that can be inadequate and lead to incorrect geosteering decisions. The core of the newly developed software is an inversion algorithm based on transversely isotropic layered Earth with an arbitrary number of layers. The following model parameters are determined in real time: horizontal and vertical resistivities and thickness of each layer, formation dip, and azimuth. The inversion algorithm is based on the method of the most-probable parameter combination. The algorithm has good performance and excellent convergence because of its enhanced capability of avoiding local minima. This capability enables interpretation of real-time resistivity data, including azimuthal and extra-deep measurements. A graphical user interface (GUI) was developed to provide an interactive environment for each stage of the resistivity data interpretation process: preview of input resistivity logs, initial preprocessing and filtering of raw data, creation of initial guess, running inversion and viewing inversion results, and quality-control indicators. Applications of the developed software will be shown on a series of synthetic examples and field data from the North Sea and Gulf of Mexico (GOM). This newly developed software is currently in use for real-time reservoir navigation and post-well analysis.

Azimuthfinder: ferramenta para a extração de dados e apoio na análise estrutural

Apresenta-se uma ferramenta computacional denominada de AzimuthFinder, para funcionamento dentro do conjunto de programas do ArcGis®. O programa desenvolvido na linguagem Python tem por finalidade facilitar e otimizar a geração de tabelas de dados azimutais, a partir de lineamentos estruturais previamente traçados em imagens de satélite, fotografias aéreas ou mapas geológicos em meio digital. As características do AzimuthFinder permitem que, a critério do usuário, sejam geradas diferentes tabelas para o mesmo objeto de análise, dependendo do peso relativo atribuído aos lineamentos, por exemplo dando maior peso àqueles de traçado mais longo. Outra característica da ferramenta é a exportação dos dados no formato TXT, que é universal para vários tipos de programas, com formatação específica para softwares como o Stereo32, Win Tensor, OpenStereo e StereoNet 7, que por sua vez são softwares livres preparados para a confecção de diagramas de rosetas. Os testes com a ferramenta demonstraram que é bastante eficiente e rápida para a geração das tabelas azimutais, facilitando de maneira eficaz a confecção de diagramas de rosetas necessários à análise estrutural em áreas essencialmente submetidas à deformação frágil.

Plasma turbulence of nonspecular trail plasmas as measured by a high‐power large‐aperture radar

AbstractHigh‐power, large‐aperture radars have been used to characterize plasmas formed as meteoroids ablate in Earth's atmosphere. These plasmas are referred to as heads, the plasmas surrounding the meteoroids, and trails, the plasmas left behind by the meteoroids. A subset of trails is nonspecular trails, which are detected when the radar beam is quasi‐perpendicular to the magnetic field. Radar returns from trail plasma are thought to originate from field‐aligned irregularity reflections that form due to turbulence within the trail. In this paper, we present theory and analysis of plasma trail diffusion using nonspecular trails detected by the Advanced Research Project Agency Long‐range Tracking and Identification Radar. These data include dual frequency, dual polarized, and high‐range resolution in‐phase and quadrature returns with azimuth and elevation data. We present turbulence onset times for nonspecular trails and derive comparisons to models. We compare diffusion coefficients calculated from the decay in signal return with ambipolar diffusion coefficients derived for specular meteor trails. These results, in conjunction with an analysis of the diffusion perpendicular and parallel to the magnetic field, demonstrate that the ambipolar diffusion coefficient is not a sufficient description of the turbulent diffusion in nonspecular trails and that other influences, such as external electric fields and anomalous cross‐field diffusion, must be considered when calculating the diffusion coefficients of nonspecular trails. In addition, we examined these results with respect to the polarization of the returns and found similar trends between all polarizations with slight differences for the right circular return.

Anisotropic permeability in fractured reservoirs from frequency‐dependent seismic Amplitude Versus Angle and Azimuth data

ABSTRACTAttempts have previously been made to predict anisotropic permeability in fractured reservoirs from seismic Amplitude Versus Angle and Azimuth data on the basis of a consistent permeability‐stiffness model and the anisotropic Gassmann relations of Brown and Korringa. However, these attempts were not very successful, mainly because the effective stiffness tensor of a fractured porous medium under saturated (drained) conditions is much less sensitive to the aperture of the fractures than the corresponding permeability tensor. We here show that one can obtain information about the fracture aperture as well as the fracture density and orientation (which determines the effective permeability) from frequency‐dependent seismic Amplitude Versus Angle and Azimuth data. Our workflow is based on a unified stiffness‐permeability model, which takes into account seismic attenuation by wave‐induced fluid flow. Synthetic seismic Amplitude Versus Angle and Azimuth data are generated by using a combination of a dynamic effective medium theory with Rüger's approximations for PP reflection coefficients in Horizontally Transversely Isotropic media. A Monte Carlo method is used to perform a Bayesian inversion of these synthetic seismic Amplitude Versus Angle and Azimuth data with respect to the parameters of the fractures. An effective permeability model is then used to construct the corresponding probability density functions for the different components of the effective permeability constants. The results suggest that an improved characterization of fractured reservoirs can indeed be obtained from frequency‐dependent seismic Amplitude Versus Angle and Azimuth data, provided that a dynamic effective medium model is used in the inversion process and a priori information about the fracture length is available.

Validation of Geostationary Satellite Orbit Determination Using Single-Station Antenna Tracking Data

A method to precisely estimate the azimuth bias for the geostationary satellite is introduced and evaluated with orbit-determination results. The issue analyzed in this paper is the singularity associated with the simultaneous estimation of the satellite’s position and azimuth bias using tracking data from a single ground station when it is located near the longitude of the ground control center. The present method of orbit estimation eliminates the azimuth bias of real tracking data using redundant ranging data from an external station and the predicted azimuth data. The accuracy of the orbit determination employing the corrected azimuth data is verified by comparing it to the ephemeris adjusted using ranging data from two ground stations. To confirm the accuracy, the longitude and latitude of the satellite ground track are compared with the optical telescope scanning results. The accuracy of the present orbit determination satisfies within 2.0 km root sum squares when compared with the ephemeris made by orbit determination using ranging data from two stations.