An experimental investigation of hanging ice dam formation
Bibliographic record
Abstract
Understanding the formation of hanging ice dams could reduce energy losses, and consequent financial losses, experienced at northern hydroelectric generating stations. Despite several studies that focused on hanging ice dams, a lack of research has been identified in the literature, and no comprehensive study on the factors influencing hanging ice dam formation has been conducted. No previous studies have been conducted to simulate a real world geometric condition that influences the evolution of hanging ice dam. The research presented in this thesis attempts to address this gap. A better comprehension of dynamics beneath a hanging ice dam will help river ice engineers to reduce economic, environmental, and ecological damages. Experimental investigations were conducted in a fixed-bed, with flat (zero sloped) flume in the Hydraulics Research & Testing Facility (HRTF) at the University of Manitoba. Experiments were conducted to investigate the formation of a hanging ice dam and its evolution in terms of areal extent, average thickness, length and maximum width under different flow conditions (e.g., Froude number and ice volume). The effect of various ice concentrations on the same variables was also tested. The whole investigation was divided into two primary conditions; firstly, experiments were conducted to investigate the effects of different Froude numbers on the evolution of hanging ice dam where ice concentration was kept constant. Additional experiments were later conducted to observe the effect of different ice concentrations on hanging ice dam formation keeping the Froude number at a fixed value. A high-resolution GoPro camera was installed above the flume to get top-down photographs at regular intervals during the experiments. Emphasis was also given on how a hanging ice dam develops under a thin ice cover for a certain flow condition. An underwater laser scanner was deployed to observe the approximate shape of hanging ice dams and the changes of maximum thickness. The results indicate that Froude number has a significant impact on the mentioned parameters during hanging ice dam formation. Flow from a narrow channel that outfalls into a wider lake (higher cross sectional area) acts as a surface jet. The evolution and decay of the surface jet are directly related to the streamwise and lateral development of hanging ice dams. Ice concentration also plays an important role in hanging ice dam development. The formation of a hanging ice dam depends on the ice transport capacity and the result of the experiments from this study supports this concept developed by Shen and Wang (1995). It is believed that the results from this experiment will improve our fundamental understanding of hanging ice dam formation, and can be used for validation of subsequent numerical models.
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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 | 0.000 | 0.001 |
| 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 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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 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".