Stability and numerical dispersion analysis of CE-FDTD method
Bibliographic record
Abstract
The complex-envelope finite-difference time-domain (CE-FDTD) method has been developed in order to efficiently simulate electromagnetic structures with band-limited signals. This method has most often been formulated in terms of wave equations, leaving its numerical properties significantly understudied. In this paper, full-wave CE-FDTD formulations, and a comprehensive analysis of the numerical stability and dispersion of this method are presented. It is found that that the maximum time step allowed for stability is strongly dependent upon the ratio of the carrier wavelength to spatial step sizes. When this ratio is larger than a threshold value, the time step is bounded by a Courant-Frederick-Levy (CFL) condition. When this ratio is lower than the threshold value, the time step is no longer bounded by this stability condition. However, in such instances, the associated numerical dispersion errors become unacceptably large (more than 200%). Therefore, in comparison with the conventional FDTD method, the CE-FDTD method is proven to be not advantageous in terms of computation efficiency for an accuracy of a similar 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 | 0.001 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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 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".