Acoustic Reflectivity From Variously Oriented Orthorhombic Media: Analogies to Seismic Responses From a Fractured Anisotropic Crust
Bibliographic record
Abstract
Abstract The variations in the strength of seismic reflections with both angles of incidence and azimuth are being used to constrain the orientations and degrees of mechanical anisotropy of geological formations. This information is often used in turn to infer the directions of fracturing and stress usually assuming simplified geological structures that in many cases are not realistic. In order to further understand this problem, the reflectivities from a set of variously titled samples cut from a single block of a common anisotropic composite material are measured with both angles of incidence and azimuth in the laboratory. Each sample is analogous to a formation in which the fracture sets increasingly dip. The observed responses differ from plane wave theory due to the finite nature of the experiment. However, the deviations are well accounted for by modeling the acoustic reflectivity using its bounded pulse. As expected, the reflectivities vary with the sample tilt, the angle of incidence, and the azimuth at which the measurements are made. However, some of these responses, such as the precritical reflectivities, do not appear to strongly vary with azimuth for a given sample. Critical angle phenomena, too, must be used cautiously as the observed reflectivity peaks do not lie at the exact critical angle. These results suggest that reflectivities could be an important source of information with regard to the spatial orientation of anisotropic layer.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".