Temperature Coefficients of Direct Voltage Reference Standards at National Research Council Canada
Bibliographic record
Abstract
We experimentally determine the temperature coefficients of direct voltage reference standards known as Fluke model 732B at the National Research Council Canada. Two units, used as references, are maintained at ambient temperature for the entire measurement duration of 4 weeks. Ambient conditions are monitored using calibrated environmental data loggers. The standards under test are placed into a temperature-regulated air bath, where calibrated environmental data loggers monitor bath conditions near the voltage terminals and near the thermistor terminals. The following quantities are measured: voltage difference between standard under test and reference standard for both 10 V and 1.018 V channels, thermistor resistance of all standards, environmental conditions both inside and outside the air bath. The air bath temperature is set to stay on alternate weeks at higher and lower temperatures following the sequence (25, 20, 25, 20) °C. The ambient temperature is between 21 and 22 °C. The entire process is repeated a second time with the locations of the standards under tests and reference standards inverted. Data analysis consists of calculating the average temperature-induced voltage and resistance changes and dividing the results by the measured temperature change to obtain the temperature coefficients. A detailed uncertainty analysis is performed. The results are compared to manufacturer specifications. The majority of our standards are better than specifications, even when taking into account the measurement uncertainties. Such experiments are beneficial, as they allow the identification of the standards with the smallest temperature coefficients to be used as direct voltage reference in client calibration services. The results can be combined into a thermistor resistance coefficient, which can be used to provide a quantitative estimate for the size of the largest temperature-induced change of resistance that has negligible effect on the voltage outputs for a given tolerance level.
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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 | 0.004 | 0.015 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.004 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.004 |
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".