Simultaneous Sources Research Articles

Convergence analysis of a coherency‐constrained inversion for the separation of blended data

ABSTRACTBlended or simultaneous sources have been the focus of a good deal of interest recently. In conventional acquisition the time intervals between successive sources are large enough to avoid interference in time. In blended acquisition, temporal overlap between source responses is allowed. The procedure of retrieving data as if they were acquired in the conventional way is called deblending. This is an essential step if standard processing flows are to be applied.Several inversion techniques have been proposed for solving this ill‐posed problem. We study the properties of an iterative estimation and subtraction algorithm that integrates a coherency‐pass filter in a dedicated iteration. We begin by stating the problem we wish to solve and develop a new, more general, interpretation of the method. We then apply an algebraic analysis of the iteration to establish the convergence characteristics of the algorithm. In order to facilitate this analysis, the notion of leakage subspace is introduced, i.e., a subspace where energy that cannot be uniquely assigned to one of the sources resides. We find that a unique solution exists, if, and only if, there is no leakage subspace. If a unique solution does not exist, then the iteration converges to a least‐norm solution contaminated by the projection of the initial guess onto the leakage subspace. The insights gained by this analysis lead us to the development of a simple tool that can provide valuable information during the design of a blended survey. Finally we present results from the application of this method to real blended marine data and then draw our conclusions.

Foreword

Geophysical ProspectingVolume 60, Issue 4 p. 589-590 Foreword Claudio Bagaini, Claudio BagainiSearch for more papers by this authorGary Hampson, Gary HampsonSearch for more papers by this authorChristine Krohn, Christine KrohnSearch for more papers by this authorIan Moore, Ian MooreSearch for more papers by this author Claudio Bagaini, Claudio BagainiSearch for more papers by this authorGary Hampson, Gary HampsonSearch for more papers by this authorChristine Krohn, Christine KrohnSearch for more papers by this authorIan Moore, Ian MooreSearch for more papers by this author First published: 15 June 2012 https://doi.org/10.1111/j.1365-2478.2012.01093.xCitations: 1 No power can stop an idea whose time has come (Victor Hugo, Histoire d'un Crime, 1877) Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume60, Issue4Special Issue: Simultaneous Source Methods for Seismic DataJuly 2012Pages 589-590 RelatedInformation

Microwave Data Inversions Using the Source-Receiver Compression Scheme

We apply a source-receiver compression approach to reduce the computational time and memory usage of the nonlinear inversion approaches for interpreting three-dimensional microwave data. By detecting and quantifying the extent of redundancy in the data, we assemble a reduced set of simultaneous sources and receivers that are weighted sums of the physical sources and receivers employed in the measurement setup. Because the number of these simultaneous sources and receivers can be significantly less than those of the physical sources and receivers, the computational time and memory usage of any inversion method such as steepest-descent, nonlinear conjugate-gradient, contrast-source inversion, and quasi-Newton can be tremendously reduced. The scheme is based on decomposing the data into their principal components using a singular-value decomposition approach and the data compression is done through the elimination of eigenvectors corresponding to small eigenvalues. Consequently, this will also suppress the effect of noise in the data. As a concept demonstration we show that this approach has the potential of significantly reducing both computational time and memory usage of the Gauss-Newton inversion method by few orders of magnitude.

The acquisition and processing of dithered slip‐sweep vibroseis data

ABSTRACTWe introduce the distance‐separated dithered slip‐sweep vibroseis acquisition technique with the objective of maximizing acquisition productivity for land data whilst maintaining the prestack amplitude fidelity required for detailed amplitude analysis. High productivity is achieved through the use of simultaneous sources and the technique is enabled by the large channel count, continuous recording and rule‐based acquisition technologies inherent in modern land acquisition systems. The technique is very flexible and allows surveys to be designed such that the source‐interference effects, after source separation, are limited to an acceptable level.Two examples illustrate the effectiveness of the technique. Firstly, we simulate a 2D, dithered data set by summing pairs of shots acquired conventionally. After separation using a sparse inversion technique, the interference noise due to simultaneous shooting is substantially eliminated and the prestack and post‐stack data are comparable with those obtainable with sequential shooting using the same number of shot locations.The second example is based on a 3D field test, in which up to 3 fleets of 2 vibrators were swept simultaneously and up to 4 fleets swept with some time overlap. The simultaneous‐source data set is coincident with existing data sets acquired with flip‐flop and slip‐sweep methods in the same area, each requiring significantly more acquisition effort. Migrated images for all three data sets are equivalent, even when no specific attempt is made to remove the interference in the simultaneous‐source data set. Separation using sparse inversion is effective in attenuating this interference prestack and is necessary for detailed amplitude analysis. It is envisaged that separation by sparse inversion will become more important as the number of simultaneous sources is increased, or the minimum distance between fleets that sweep simultaneously is decreased.

Source Separation on Seismic Data: Application in a Geophysical Setting

This article gives a brief description of the degenerate unmixing estimation technique (DUET) and applies it in a geophysical setting. Source separation has not been fully addressed by geophysicists and is a crucial first step to locating simultaneous sources, which in turn helps with understanding the dynamics of the sources and their source mechanisms. DUET is applied to synthetic seismic signals. The source separation method works success fully to separate two contemporary explosive sources, and two simultaneous oblique tensile cracks in a three-dimensional (3-D) structural model of Mount Etna. The method has also been applied to field recordings on Mount Etna since 2008. The method separates long-period (LP) events from tremor, LP events from volcano tectonic (VT) events, and different sources of tremor from each other.

Unconstrained simultaneous source land data processing*

ABSTRACTIn the past few years, significant effort has been put into developing land acquisition field techniques that can improve production performance, reduce acquisition cost and increase seismic data quality. In 2010, Saudi Aramco conducted a high‐productivity, unconstrained, simultaneous source acquisition field test. A fixed, active super‐spread continuously recorded 18 single vibrators operating simultaneously in 18 separate quadrants. The test employed high source density, unique up‐sweep lengths and spatial source separation to maximize the seismic data quality and minimize the effects of crosstalk. This test achieved an optimum productivity rate of 45,000 vibrator points (VP) per 24 hours with real time QC. In this paper, we demonstrate that the conventional processing techniques produced acceptable images despite noise interference or crosstalk. In addition, we illustrate suitable deblending processing workflows and algorithms for attenuating source interference noise. The objective of the deblending processing is to attenuate random uncompressed crosstalk and to improve the resolution of the prestack migrated time image. Finally, comparisons with legacy 3D seismic data acquired over the same area are depicted. This paper reviews how this unique integration of data acquisition and deblending processing yields a superior seismic image.

When two sources of fluency meet one cognitive mindset

Fluency, the subjective experience of ease associated with information processing, has been shown to affect a host of judgments. Previous research has typically focused on specific factors that affect the use of a single, specific fluency source. In the present study we examine how cognitive mindsets, or processing modes, moderate fluency emanating from two simultaneous sources of fluency. As a cognitive mindset manipulation, participants performed Jacoby’s process dissociation paradigm. Subsequently, participants engaged in a metamemory task that incorporates (and can separately measure the influence of) two simultaneous sources of fluency: familiarity and accessibility. Our results confirmed that our content-unrelated mindset procedure had affected the use of fluency. Moreover, the use of both fluency sources was attenuated, demonstrating the generality of the effect. The findings highlight the causal dependency of fluency on a complex, cognitively-rich environment.

Institutionalizing Ethical Innovation in Organizations: An Integrated Causal Model of Moral Innovation Decision Processes

This article answers several calls—coming as well from corporate governance practitioners as from corporate governance researchers—concerning the possibility of complying simultaneously with requirements of innovation and ethics. Revealing the long-term orientation as the variable which permits us to link the principal goal of organization, being “survival,” with innovation and ethic, the article devises a framework for incorporating ethics into a company’s processes and strategies for innovation. With the principal goal of organizations being “survival” in the long-term, it is assumed that innovation is necessary in order to realize a going concern. Firms that do not innovate and adapt to rapidly changing business environments are less likely to be sustainable. Thus, it is in a business’ best interests to adopt an innovation process for long-term success. We posit that there are two simultaneous sources of innovation and change that are unavoidable and embedded in the corporate landscape. First, we argue for genetically embedded, Darwinian explanations for adaptations that enable an entity’s survival. This view is combined with more conventional, social science explanations for change. Our new, comprehensive model of the governance of innovation processes hinges on the one hand on an organization’s long-term orientation, which we argue, is not possible without a consideration of an ethical dimension. On the other hand, the model employs, for the first time, the concept of duality, in order to make the positive coexistence of innovation and ethic analytically visible. Guided by this concept the roots of the ethic within innovation are traced from both natural science forces for change, and cultural pressures operating on members of an organization. We present our Integrated Causal Model of Innovation and propose theoretical relationships that will generate numerous avenues for future research in the field, and help managers to reorient their governance strategies.

Functional imaging of the hemodynamic sensory gating response in schizophrenia

The cortical (auditory and prefrontal) and/or subcortical (thalamic and hippocampal) generators of abnormal electrophysiological responses during sensory gating remain actively debated in the schizophrenia literature. Functional magnetic resonance imaging has the spatial resolution for disambiguating deep or simultaneous sources but has been relatively under-utilized to investigate generators of the gating response. Thirty patients with chronic schizophrenia (SP) and 30 matched controls participated in the current experiment. Hemodynamic response functions (HRFs) for single (S1) and pairs (S1 + S2) of identical ("gating-out" redundant information) or nonidentical ("gating-in" novel information) tones were generated through deconvolution. Increased or prolonged activation for patients in conjunction with deactivation for controls was observed within auditory cortex, prefrontal cortex, and thalamus in response to single tones during the late hemodynamic response, and these group differences were not associated with clinical or cognitive symptomatology. Although patient hyperactivation to paired-tones conditions was present in several regions of interest, the effects were not statistically significant for either the gating-out or gating-in conditions. Finally, abnormalities in the postundershoot of the auditory HRF were also observed for both single and paired-tones conditions in patients. In conclusion, the amalgamation of the entire electrophysiological response to both S1 and S2 stimuli may limit hemodynamic sensitivity to paired tones during sensory gating, which may be more readily overcome by paradigms that use multiple stimuli rather than pairs. Patient hyperactivation following single tones is suggestive of deficits in basic inhibition, neurovascular abnormalities, or a combination of both factors.

Fast source optimization involving quadratic line-contour objectives for the resist image

In Abbe's formulation, source optimization (SO) is often formulated into a linear or quadratic problem, depending on the choice of objective functions. However, the conventional approach for the resist image, involving a sigmoid transformation of the aerial image, results in an objective with a functional form. The applicability of the resist-image objective to SO or simultaneous source and mask optimization (SMO) is therefore limited. In this paper, we present a linear combination of two quadratic line-contour objectives to approximate the resist image effect for fast convergence. The line-contour objectives are based on the aerial image on drawn edges using a constant threshold resist model and that of pixels associated with an intensity minimum for side-lobe suppression. A conjugate gradient method is employed to assure the convergence to the global minimum within the number of iterations less than that of source variables. We further compare the optimized illumination with the proposed line-contour objectives to that with a sigmoid resist-image using a steepest decent method. The results show a 100x speedup with comparable image fidelity and a slightly improved process window for the two cases studied.

On the relation between seismic interferometry and the simultaneous‐source method

ABSTRACTIn seismic interferometry the response to a virtual source is created from responses to sequential transient or simultaneous noise sources. Most methods use crosscorrelation, but recently seismic interferometry by multidimensional deconvolution (MDD) has been proposed as well. In the simultaneous‐source method (also known as blended acquisition), overlapping responses to sources with small time delays are recorded. The crosstalk that occurs in imaging of simultaneous‐source data can be reduced by using phase‐encoded sources or simultaneous noise sources, by randomizing the time interval between the shots, or by inverting the blending operator. Seismic interferometry and the simultaneous‐source method are related. In this paper we make this relation explicit by deriving deblending as a form of seismic interferometry by MDD. Moreover, we discuss a deblending algorithm for blended data acquired at the surface.

Simultaneous Source Localization and Polarization Estimation via Non-Orthogonal Joint Diagonalization with Vector-Sensors

Joint estimation of direction-of-arrival (DOA) and polarization with electromagnetic vector-sensors (EMVS) is considered in the framework of complex-valued non-orthogonal joint diagonalization (CNJD). Two new CNJD algorithms are presented, which propose to tackle the high dimensional optimization problem in CNJD via a sequence of simple sub-optimization problems, by using LU or LQ decompositions of the target matrices as well as the Jacobi-type scheme. Furthermore, based on the above CNJD algorithms we present a novel strategy to exploit the multi-dimensional structure present in the second-order statistics of EMVS outputs for simultaneous DOA and polarization estimation. Simulations are provided to compare the proposed strategy with existing tensorial or joint diagonalization based methods.

A 3D simultaneous source field test processed using alternating projections: a new active separation method

ABSTRACTIn 2008, a wide azimuth simultaneous source (SimSrc) 3D data set was acquired over an area coinciding with an existing conventional wide azimuth survey. Using two (nearly) simultaneous sources provided twice the number of shots, an increased shot density and twice the fold for essentially the same acquisition time. Although the improved sampling for the SimSrc data was predicted to yield improvements in processes such as 3D multiple attenuation and migration, cross‐talk between the sources was a concern. Cross‐talk can be suppressed by known techniques such as separation algorithms that estimate the individual shots and thereby separate SimSrc records into their constituent shots. However, separation algorithms available at the time suffered from aliasing and were not effective for severely shot‐aliased data such as those encountered in the experimental data set, which had a 75‐m in‐line shot spacing, half that typical for wide azimuth geometries.In this paper we present a new separation technique called the Alternating Projection Method (APM), which is demonstrated to be robust in the presence of aliasing. Through comparisons with conventional wide azimuth data we show that 3D multiple removal and migration are both aided by the increase in shots. Moreover, the high quality of the APM separated data indicates that prestack products such as migration angle gathers will have better quality than was achieved a few years ago using a passive separation approach. We found that by carefully selecting and tailoring the method's projection operators, excellent separation results can be achieved efficiently.

Focus on land seismic technology: The near-surface challenge

A new era in land seismic is at hand. Growing energy demand will spur greater efforts in exploration and development into regions of the world where hydrocarbons occur in land environments. Interpreters will require accurate near-surface solutions for mapping low-relief structures and stratigraphic traps, and to improve data quality for placing horizontal wells. This will require solutions to near-surface challenges, such as energy penetration, scattering, source-generated noise, surface-generated multiples, statics, and source and receiver coupling. Solutions to these problems will become possible due to advances in seismic acquisition, including simultaneous source acquisition and wireless seismic-driven ultrahigh channel systems. Additionally, advances in seismic processing technology for processing the resulting huge data volumes will be made possible by continual growth in computational capability. These advances will for the first time allow acquisition of true 3D seismic data. This will not only result in better imaging of the subsurface, but also will allow the near surface to be addressed as an imaging problem with better description of velocities and suppression of surface-related noise.

Attenuating crosstalk noise with simultaneous source full waveform inversion★

ABSTRACTFor some acquisition geometries, the cost of Full Waveform Inversion (FWI) can be considerably reduced by inverting simultaneously encoded shots. Encoded‐shot strategies have the undesirable effect of leaving crosstalk noise in the final result. For FWI, changing the coding sequence periodically mitigates this effect. Another alternative is to use preconditioning, whereby the gradient is smoothed at every iteration along predefined directions. Preconditioning steers the solution towards accurate models while attenuating crosstalk artefacts. It also increases convergence speed and robustness to noise present in the data.

Identification of two simultaneous partial discharge sources in an oil-pressboard insulation system using acoustic emission techniques

Insulation failure is one of the major causes of catastrophic failure of transformers. It is established that partial discharge (PD) causes insulation degradation and premature failure of insulation. In power apparatus, more than one PD source may be active simultaneously. The nature of insulation degradation for multiple PD sources is different from that due to single PD source. Therefore, it will be helpful for severity assessment of insulation degradation, if the number of active PD sources are identified and classified. This paper presents a method for identification and classification of two simultaneously active PD sources using acoustic emission techniques. The acoustic emission (AE) signals are measured for laboratory simulated PD in an oil-pressboard insulation system for three different electrode systems. The measurements of partial discharge acoustic emission (PDAE) signals are carried out for single PD source and for two simultaneous PD sources. The measured signals are analyzed using discrete wavelet transform (DWT), box counting fractal dimension and lacunarity. Box counting fractal dimension and lacunarity are calculated for DWT decomposed signal of major frequency band. Energy distribution in different frequency bands of DWT decomposed signal along with box counting fractal dimension and lacunarity is used for classification of two simultaneous PD sources.

Automatic Recognition of an Unknown and Time-Varying Number of Simultaneous Environmental Sound Sources

Automatic Recognition of an Unknown and Time-Varying Number of Simultaneous Environmental Sound Sources

The High-Power of DC Power with Auto Tracking Power Frequency

This paper analyzes the reason that the common thyristor trigger is unable to fulfill power supply in wide range changes of frequency. The high precise frequency/voltage converter is used to monitor and track frequency changes of the simultaneous power supply. The simultaneous signal and charge current source are provided by the converter for saw tooth wave trigger. The frequency of saw tooth wave changes as the same time the frequency of power supply changes in wide range. However, the amplitude of the saw tooth wave can be kept constant. This can achieve the controlled angle of the thyristor trigger does not change with the large-scale voltage frequency changes of the simultaneous power supply when the same Phase-shifted control voltage was used.

IT assets, organization capital and market power: Contributions to business value

How much IT capital contributes to the economic value of firms is a relevant but complex issue, since the contribution may come from different sources that are difficult to separate. In this paper, we model the determinants of the economic value of multi-asset firms with market power when the adjustment costs of investing in IT capital turn into organization capital, increasing the future cash flow of the firm. The resulting valuation equation, new in the literature, has four simultaneous sources of economic value: (i) purchase costs of the assets, (ii) adjustment costs, (iii) organization capital, and (iv) rents from market power. The model is tested with a unique data base from Spanish banks in a time period when these banks invested heavily in IT capital. We find that 54% of the economic value of the representative bank corresponds to the purchase cost of material and immaterial assets, including IT capital. The remaining 46% corresponds to the contributions of: adjustment costs (17%), organization capital (7%) and rents from market power (22%).

Unpaced production lines with three simultaneous imbalance sources

Purpose – The purpose of this paper is to investigate the performance of unpaced reliable production lines that are unbalanced in terms of their mean operation times, coefficients of variation and buffer capacities.Design/methodology/approach – Simulations were carried out for five‐ and eight‐station lines with various buffer capacities and degrees of means imbalance. Throughput, idle time and average buffer level performance indicators were generated and statistically analysed.Findings – The results show that an inverted bowl allocation of mean service times, combined with a bowl configuration for coefficients of variation and a decreasing order of buffer sizes results in higher throughput and lower idle times than a balanced line counterpart. In addition, considerable reductions in average inventory levels were consistently obtained when utilizing a configuration of progressively faster stations, coupled with a bowl‐shaped pattern for coefficients of variation and an ascending buffer size order.Research...