Frequency Dependence in AC Harmonic Interference to Pipelines
Bibliographic record
Abstract
Abstract Studies of Alternating Current (AC) interference on pipelines from nearby power lines usually consider the fundamental (50Hz or 60Hz) frequency of the power line currents. However, these currents can also contain considerable harmonics of the fundamental AC frequency. Measurements on pipelines in Canada and Sweden have shown that these harmonics can produce significant interference in the pipe-to-soil potentials. The electromagnetic fields experienced by the pipeline are dependent on three types of parameters. The first is associated with the phase relations of the power line harmonics, classified as ‘positive sequence’, ‘negative sequence’, and ‘zero sequence’. The second is related to the conductivity of the host media (ground) that affects the electromagnetic field experienced by a pipeline. The third is pipeline series impedance and parallel admittance, which introduces additional frequency dependence. This paper examines the frequency dependence of the phase relation of the power line currents, the Earth response, and the pipeline response and shows how they can be combined to provide an AC risk assessment.
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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) | 0.002 | 0.001 |
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".