Investigation of acoustic properties of snow-covered sea ice
Notice bibliographique
Résumé
The paper presents results of field observations of hydroacoustic characteristics of snow-covered ice cover in shallow seas of the Arctic shelf. The purpose of the research was to determine the quantitative characteristics of the reflection and absorption coefficients of sound from the bottom of the drifting ice cover, as well as the Doppler broadening of the frequency spectrum of acoustic signals depending on the thickness of the ice, the structure of the reflecting surface, the thickness of the snow cover, and the ice drift speed. The objective of the research was to obtain the data necessary for choosing optimal parameters of specialized hydroacoustic equipment designed to monitor ice conditions in the areas of operation of offshore oil and gas platforms. Researches were conducted in areas of active construction of engineering marine constructions and carrying out the transport operations. The research methodology was based on the use of an autonomous measuring complex, which for a long period was installed on the bottom of the sea at depths of 50 to 130 m. The recording system consisted of the following components: upward looking pulse sonar of the IPS-5 type produced by the Canadian company ASL; the Doppler meter of the ice drift speed ADCP (the RDI firm); and a RSM-7 electromechanical current meter. All devices operated in continuous mode with a measurement cycle of 1s, the results were recorded in memory and processed after lifting the devices to the surface. The time delays of signals reflected from the ice cover, as well as the amplitudes and variations of the sound attenuation depending on the reflectance and absorption coefficients were recorded in the memory of the up-looking sonar. Variations of time delays were used to calculate a settlement of ice formations and to determine the shape of the reflective surface, including the angles of inclination of ice keels. Doppler shift of frequency of reflected acoustic signals and broadening of the frequency spectrum were calculated using values of the ice drift speed and changes of immersion depths of hummocks. Acoustic characteristics were measured repeatedly during several seasons of each year from 2010 to 2017. This investigation made possible to obtain statistical estimates of the distributions of the reflection coefficient of the sound and the quantitative values of broadening of the frequency spectrum of acoustic signals depending on the angle of incidence of the acoustic rays, the nature of the irregularities and the structure of the reflective surfaces of ice and snow cover thickness and the drift speed. The results obtained by this research allowed reasonable choosing and calculating the basic characteristics of the hydroacoustic equipment intended for runtime diagnostics of ice cover in zones of marine engineering structures.
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 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 ».