Multiple problems, including high computational cost, spurious local minima, and solutions with no geologic sense, have prevented widespread application of full waveform inversion (FWI), especially FWI seismic reflections. These problems are fundamentally related to a large number model parameters the absence low frequencies in recorded seismograms. Instead inverting for all dense model, image-guided inverts sparse space that contains far fewer parameters. We represent set values, from these...

The effects of replacing calcined clay with sewage sludge ash (SSA) treated under room temperature and high ranging from 500 °C to 900 in limestone cement (LC3) have been investigated this paper. optimal calcination for SSA was found be 800 based on the results strength microstructure observations. main inorganic components are Fe2O3, SiO2, Al2O3, CaO, which very similar LC3, but a content Fe2O3 (55–61%) P2O5 (9–10%). With different levels replacement SSA, setting time, compressive strength,...

The seismic response of palace-style timber structures is closely related to the rocking characteristics column. To accurately describe dynamic structures, a nonlinear rotational spring employed simulate behavior column base joints under excitation. Firstly, spring-rigid rod analysis model that comprehensively considers properties joints, mortise-tenon and bracket set proposed, simplified lumped mass obtained through centroid method equivalent stiffness method. accuracy verified shake table...

By minimizing the difference between synthetic and field data sets, full waveform inversion (FWI) can produce high resolution fidelity earth model parameters that are not resolvable by commonly used ray-based tomography. In this paper, we share our experience on applying 3-D acoustic time-domain to an OBC set collected over Valhall in North Sea.

Full waveform inversion (FWI) with an image‐guided gradient improves convergence by reducing the number of parameters in subsurface model. We represent model a sparse set values, and from these we use interpolation (IGI) to compute finely‐ uniformly‐sampled gradients data misfit function FWI. IGI makes models more blocky than finely‐sampled models, this blockiness space mitigates absence low frequencies recorded data. A smaller invert also reduces iterations required converge solution Tests...

In the paper, a simple-supported wooden beam is used as research object to identify damage of wood by finite element analysis and experimental research. First, ANSYS was establish solid model before after damage, then discrete wavelet transform performed on curvature mode coefficient difference index obtained obtaining high frequency coefficients. Then, location judged according sudden peak index, degree estimated fitting relationship between damage. Finally, verified test. The results show...

Large-scale seismic acquisition based on compressive sensing (CS) has been made practical recently, thanks to the advance in CS algorithms and increasing computation power (Mosher, 2014; Li, 2013). Compressive (CSA) can substantially reduce time costs with proper de-blending (CSD) especially reconstruction (CSR). Projection onto convex sets (POCS) is a very popular choice among various mathematical approaches for CSR, because of its efficiency, simple parameterization, flexibility expand...

The assessment of concrete structures' durability in chlorine environments is significantly impacted by the uncertainty inherent existing models. It introduce an integrated approach for updating these models, based on detection information structures. This narrows gap between theoretical predictions and observed structural durability. Specifically, we refine probability model critical chloride content analyzing steel bar corrosion sample proportions, using Bayesian theory greater...

In situ dynamic testing is conducted to study the characteristics of wooden structure North House main hall. The velocity response signals on measurement points are obtained and analyzed using self-interaction spectral method stochastic subspace method, yielding natural frequencies, mode shapes, damping ratios. This reveals that frequencies ratios highly consistent between two methods. Therefore, eliminate errors, average results from both modal identification methods taken as final measured...

PreviousNext No AccessSEG Technical Program Expanded Abstracts 19993‐D analytical migration velocity analysis I: Two‐step estimation by reflector‐normal updateAuthors: Zhaobo MengNorman BleisteinKay D. WyattZhaobo MengCenter for Wave Phenomena, Colorado School of Mines, Norman BleisteinCenter and Kay WyattPhillips Petroleum Companyhttps://doi.org/10.1190/1.1820868 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail...

Velocity/depth ambiguity in the conventional premigration (time domain) velocity analysis has been studied by Bickel (1990) and Lines (1993) for horizontal reflector case. Rathor (1997) extended this to dipping These studies answered some important questions that arose traditional common midpoint (CMP) time‐domain analysis. However, it is not clear their conclusions apply migration (MVA) prestack‐migrated depth domain.

Accurate subsurface velocity estimation is crucial in seismic exploration, especially for prestack depth migration, conversion, geopressure prediction and AVO attribute computation. 3D reflection tomography the most accurate method available estimation. The challenge that we face designing an tomographic system capable of efficiently handling large volumes data acquired over increasingly complex targets. To address this need have developed a using tetrahedra‐based model parameterization....

In order to inspect the influence of micro-vibration excited by vehicles on timber structure Xi'an Bell Tower, dynamic response test had been carried out. The vibration model has established and security evaluation accomplished based GB/T50452-2008. results indicated that differences levels in are extraordinary obvious during different interval time. Comparing column foundation, upper floor enlarged obviously. horizontal velocity (in NS EW directions) also obvious. It is shown at top...

Rock material is a kind of mineral assemblage with complex structural heterogeneity, whose mechanical behavior strongly affected by water or moisture content. In this work, we carried out series laboratory tests to investigate the response (e.g., deformation, strength, and failure characteristics) Yunnan limestone in natural saturated states. Our test results show that (1) after saturation, stiffness strength degenerate considerably. Compared condition, elastic modulus, deformation tensile...

Summary Salt body delineation plays a critical role in oil and gas exploration the Gulf of Mexico. Common practices for building salt model rely on interpreting top (TOS) first, then followed by base (BOS) migrated image. This process can be extremely time consuming resource intensive complex geometry. even more tedious presence overhangs. The interpretation base-salt geometry is often most challenging part workflow because BOS typically poorly imaged due to limited illumination, which...

Three‐dimensional finite element model of the wood structure‐foundation North House’s main hall in Tianshui under ground traffic excitation was established, and damage first‐floor longitudinal beam structure simulated by method. The node acceleration response signals on beams were decomposed with a wavelet packet. packet energy curvature difference index proposed to determine structural location. results show that can decide location middle part beam, value increases increase degree. If SNR...

Surrounding rock pressure, water and joint roughness are the important factors that affect fractured mass seepage. It is of great significance to quantify influence these through experiments. In this study, fracture surfaces were measured. Next, 3D coordinates extracted with using Geomagic software, was described mean variance protrusion height equidistant fluctuation angle, which acquired calculation. Stress-seepage coupling test then conducted on samples a triaxial apparatus, effects...

We show here a successful case study of applying 3D model-based water-layer demultiple (MWD) for shallow water data from West Africa. MWD (Wang et al., 2011) is especially useful when the water-bottom recorded beyond critical angle, depth roughly less than half near offset. that in such an environment, provided advantageous alternative to SRME (Verschuur al, 1997) removing water-layer-related multiples. also simultaneous subtraction and models better attenuates multiples separate two models.

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The assessment of concrete structure durability in chlorine environments is significantly impacted by the uncertainty inherent existing models. It introduces an integrated approach for updating these models based on detection information structures. This narrows gap between theoretical predictions and observed structural durability. Specifically, we refined probability model critical chloride content analyzing steel bar corrosion sample proportions using Bayesian theory greater accuracy....