A Two‐Domain Approach Using CAT Scanning to Model Solute Transport in Soil
Bibliographic record
Abstract
Abstract Multi‐region modeling can be used to simulate dynamics of preferential flow in soils. However, the criteria used to determine boundaries between flow regions have been defined arbitrarily up to now. Therefore, there is a need to develop a reliable technique to isolate and characterize flow domains in soil. The primary objective of this study was to develop a reliable method for isolating and characterizing flow domains in a large undisturbed soil column using a computer assisted tomography (CAT) scanner. This approach allows for real‐time examination of flow mechanisms through soil macropores at various depths along the length of soil columns. With the knowledge of the macropore structure and the spatial distribution of the solute, breakthrough in the macropore and matrix flow domains was evaluated. Flow in the matrix domain suggested that part of the matrix contains small pores that are connected to macropore networks. These pores contribute to a rapid tracer buildup in the matrix domain. The breakthrough curves (BTCs) measured in the matrix domain were fitted using the convection dispersion equation (CDE) with CXTFIT 2.0. The macropore domain was divided into two regions, namely the laminar and turbulent regions. A modified version of Poiseullle's law was used to model solute breakthrough in the laminar region. For the turbulent region, a new formula was derived based on Manning's equation. The modifications were done so that these simple models would take into account the distribution density functions of macropore size and hydraulic radius. This approach provides reliable approximation of the overall breakthrough of solutes in the macropore domain.
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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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".