Spin-echo measurements for capillary rheometry at low field
Bibliographic record
Abstract
A single spin-echo, acquired in the presence of a constant magnetic field gradient, has a phase proportional to the average velocity of the sample and an amplitude determined by the distribution of velocities for laminar flow in a pipe. If we make assumptions about symmetry, it is therefore possible to reconstruct a velocity profile from a series of spin echoes acquired with different echo times, . The velocity profile encompasses a range of shear stresses and so describes the shear-rate dependence of the fluid viscosity, making this a rapid, non-invasive rheometric measurement. The appeal of this approach lies in its simplicity: a constant, uniform magnetic field gradient can be readily constructed using low-field permanent magnets and the resulting magnetic resonance instrument is relatively cheap and easily sited. In order to extend the range of fluids to which such a rheometer can be applied, we have designed a pre-measurement polarization unit to maximize the polarization of fluids with a long , such as aqueous solutions.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
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".