Realizing the redefined Kelvin: Extending the life of ITS-90
Bibliographic record
Abstract
Following the redefinition of the kelvin, the user is presented with a more nuanced traceability route for temperature through the mise en pratique for the definition of the kelvin (MeP-K-19).Here we describe research to address several present and potential shortcomings with the current main dissemination route, namely the International Temperature Scale of 1990 (ITS-90).The ITS-90 has served the global temperature measurement community well, providing reliable, low uncertainty traceability for over 30 years.However, there are some potentially life-limiting issues for it.Among these are the impact of the main types (1 and 3) of non-uniqueness which represent an important contribution to the uncertainties achievable with the ITS-90, and the possible need to identify an alternative to the mercury triple point, a key fixed point of the ITS-90 whose use could be banned by an international treaty.Significant progress has been made in addressing these problems through a) new determinations of Type 3 non-uniqueness which have been undertaken in the range -189 C to 156 C; b) a comprehensive evaluation of Type 1 non-uniqueness on a large number of Standard Platinum Resistance Thermometers (SPRTs) across multiple temperature regions; c) comparison of high temperature SPRTs in pressurecontrolled heat pipes to characterize Type 3 non-uniqueness between 660.323 C and 961.78 C and d) new designs of CO2 and SF6 cells for use with long-stem SPRTs.The fixed-point cells have been improved compared to previous versions by using purer gases and more stable and uniform temperature-controlled baths, and by the development of a flexible set-up that can accommodate both capsule and long-stem SPRTs.The effect of replacing mercury on the ITS-90 interpolating equations and uncertainty propagation has also been investigated.
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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 | 0.000 | 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".