Geoacoustic Parameter Extraction Using Reverberation Data From the 2000 Boundary Characterization Experiment on the Malta Plateau
Bibliographic record
Abstract
This paper presents some new results from measurements of seafloor reverberation and pulse spreading using horizontal and vertical line arrays. The principal objective of this paper is to extract useful geoacoustic and bottom-scattering parameters that apply over a large ocean area. Analysis is presented on reverberation data from the 2000 Boundary Characterization Experiment performed jointly with North Atlantic Treaty Organization (NATO) Undersea Research Center (NURC), Applied Research Laboratory (ARL) of Pennsylvania State University, Defence Research and Development Canada (DRDC), and Naval Research Laboratory (NRL). Sources were SUS charges and coherent pulses. The receivers were horizontal arrays used monostatically. Data were analyzed in bands from 80 to 4000 Hz. Highlights of the reverberant returns are discussed. The experiment site is the Malta Plateau area south of Sicily, a relatively flat heavily sedimented area, but with a rocky ridge to the east. An original aspect of this paper is the design and implementation of a new automated inverse method using towed-array data to accomplish that goal. For each data set, a multiple-step simulated annealing (SA) algorithm is used together with the Generic Sonar Model (GSM). After automatically adjusting bottom loss and scattering strength, good agreement is achieved between the diffuse reverberation data and model predictions in relatively flat areas. Model/data differences are generally correlated with bottom-scattering features. Since reverberation from SUS charges typically lasts 10-40 s or more, extracted parameters apply over wide areas. Independent acoustic measurements provided a basis for a comparison with extracted values. Local bottom-loss and backscattering measurements were made by Holland in these areas. Additionally, chirp-sonar measurements were analyzed by Turgut. A comparison of geoacoustic models obtained with their methods and with this one was quite good. Comparing transmission loss (TL) predicted with Turgut's local inverse method and TL predicted with the method presented here gave answers that were usually within 3 dB of each other. Typical two-way time spreads of 0.25 s were seen at a range of 7.5 km, with normalized peak correlations of 0.5, and which were fairly consistent with predictions made using the inverse results
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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 teacher head, 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".