Notice bibliographique
Résumé
Border ice is one of many ice freeze-up processes, but it is discussed only to a limited extent in the literature. Border ice formation can be a precursor for ice jam formation that may restrict navigation and lead to flooding. This master’s thesis is mainly devoted to the research on the border ice on the Saint Lawrence River from Montréal to Québec City. This reach stays artificially open all winter because commercial ships are continuously preventing a full ice cover to form. The traffic also limits the extent of border ice.\n This study provides key information on ice formation and decay. Through analysis of Environment Canada’s historical data (ice charts from 2004 to 2009), the areal coverage of border ice is analyzed during freeze-up, winter and breakup periods. The historical information of ice coverage is collected in order to find out the factors which influence its formation and its spatial limits. Border ice growth and decay rates are also discussed. \n The thesis shows that border ice coverage has three stages including the rapid growth period at the beginning of the winter, the relatively stable period in the mid-winter and the breakup period as March progresses. During the mid-winter period, the border ice coverage sometimes drops sharply if the air temperature rises above 0 °C and/or if there is some rain. It was also found that the maximum border ice spatial limits are quite similar over the five winter seasons.\n Based on the analysis of the ice charts, a number of empirical laws regarding the formation and decay of border ice are proposed. Along the river flowing direction, the border ice is formed easily when there are obstacles particularly at the downstream end. The obstacles could include river bends, ice booms, shoals, artificial islands, bridge piers and so on. Thus, the obstacle influences the flow velocity, which is an important factor for ice formation and also provides an object against which the ice can become fast and initiate its formation.\n On average, border ice reaches 20% of its maximum coverage when the accumulated freezing degree days (AFDD) reaches 124 °C-D. This is followed by a rapid growth period that ends when the ice cover reaches about 80% of its maximum cover corresponding to AFDD equal to 247 °C-D. Border ice coverage usually reaches the maximum value when the average AFDD is 551 °C-D corresponding to the end of January.\n The winter period is characterised by a stable ice cover (>90% of max) upstream of Trois-Rivières except in the event of a mid-winter thaw. Downstream of Trois-Rivières there is no stable period as the decay begins very soon after the ice reaches its maximum value.\n Breakup is a gradual process that normally begins on about Feb. 15th downstream of Trois- Rivières and about March 1st upstream. Most ice has normally gone by March 31st. \n Moreover, the river flow velocity, river depth and Froude number along the limits of border ice once it reaches its maximal areal coverage are evaluated and analyzed. The flow velocity is almost always less than 1.0 m/s; the maximum Froude number is normally 0.1 at Lake Saint-Pierre and 0.2 in the Montréal to Sorel reach; river depth at the ice edge can vary widely.\n Through numerical modelling, it was found that border ice increased the current velocity by 0.1 m/s in the Lake Saint-Pierre reach and raised water levels by 14 cm in the Montréal to Sorel reach. \n
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».