Inclinaison orbitale

Résumé

En mécanique céleste et en mécanique spatiale, l'inclinaison orbitale, ou simplement inclinaison quand il n'y a pas d'ambiguïté, est un élément orbital d'un corps en orbite autour d'un autre. Il décrit l'angle dièdre entre le plan de l'orbite et le plan principal du système de référence (généralement le plan de l'écliptique, c'est-à-dire le plan moyen de l'orbite de la Terre, ou le plan équatorial). L'inclinaison est couramment notée i (lettre i minuscule de l'alphabet latin). Lorsque l'inclinaison est non nulle, l'orbite est dite inclinée. Le plan de l'orbite et le plan de référence sont alors deux plans sécants. La droite d'intersection des deux plans est la ligne des nœuds. L'orbite la coupe en deux points d'intersection dits nœuds. Le nœud ascendant est celui que le corps en orbite franchit en trajectoire ascendante ; le nœud descendant, celui qu'il franchit en trajectoire descendante. L'inclinaison se compte de 0 à 90° dans le cas d'une orbite directe et de 90° à

Source officielle

https://fr.wikipedia.org/wiki/Inclinaison_orbitale

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Séances de cours associées (14)

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This study aims to characterize human convective boundary layer (CBL) in a quiescent indoor environment. The study has two objectives: first, to characterize the velocity field around the thermal manikin under two ambient temperatures and body postures; and secondly, the influence of clothing insulation/design, chair design, table positioning and seated body inclination on airflow characteristics in the breathing zone of a sitting manikin is examined. The increase of the ambient temperature from 20 to 26 °C widens the CBL flow in front of the sitting manikin but do not influence the shape of the CBL in front of the standing manikin. The same temperature increase causes the reduction of the CBL mean peak velocity from 0.24 to 0.16 m/s in front of the sitting manikin. Dressing the nude manikin with thin-tight clothing ensemble reduces the peak velocity in the breathing zone from 0.205 m/s by 17%, and by 40% for thick-loose ensemble. Removing the wig increases the peak velocity from 0.17 to 0.187 m/s. Clothing and chair design have a minor influence on the velocity profile beyond 5 cm distance from the body. Closing the gap between the table and the manikin reduces the peak velocity from 0.17 to 0.111 m/s. Manikin leaned backwards induces the peak velocity of 0.185 m/s, which is 45% above the case when manikin is leaned forward. PIV measurements complemented with Pseudo color visualization (PCV) technique provide a good synergy between quantitative and qualitative airflow characteristics and can be adequately employed for the CBL investigation.

2014

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Air temperature investigation in microenvironment around a human body

Dusan Licina

The aim of this study is to investigate the temperature boundary layer around a human body in a quiescent indoor environment. The air temperature, mean in time and standard deviation of the temperature fluctuations around a breathing thermal manikin are examined in relation to the room temperature, body posture and human respiratory flow. To determine to what extent the experiments represent the realistic scenario, the additional experiments were performed with a real human subject. The results show that at a lower room air temperature (20 °C), the fluctuations of air temperature increased close to the surface of the body. The large standard deviation of air temperature fluctuations, up to 1.2 °C, was recorded in the region of the chest, and up to 2.9 °C when the exhalation was applied. The manikin leaned backwards increased the air temperature in the breathing zone, which was opposite from the forward body inclination. Exhalation through the mouth created a steady air temperature drop with increased distance from the mouth without disturbing the region of the chest. Exhalation through the nose did not affect the air temperature in front of the chest due to physics of the jets flow from the nose. The additional carbon dioxide (CO2) measurements showed that the exhaled air from the nose could penetrate the region below the chest. Small discrepancies between the results obtained with the breathing thermal manikin and a real human subject suggest that the manikin can be used for accurate measurements of occupant's thermal microenvironment.

2015

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Transport of gaseous pollutants by convective boundary layer around a human body

Dusan Licina

This study investigates the ability of the human convective boundary layer to transport pollution in a quiescent indoor environment. The impact of the source location in the vicinity of a human body is examined in relation to pollution distribution in the breathing zone and the thickness of the pollution boundary layer. The study, in addition, evaluates the effects of the room air temperature, table positioning, and seated body inclination. The human body is represented by a thermal manikin that has a body shape, size, and surface temperature that resemble those of a real person. The results show that the source location has a considerable influence on the breathing zone pollution concentrations and on the thickness of the pollution boundary layer. The highest breathing zone concentrations are achieved when the pollution is located at the chest, while there is negligible exposure for the pollution emitted at the upper back or behind the chair. The results also indicate that a decrease in personal exposure to pollutants released from or around the human body increases the extent to which the pollution spreads to the surroundings. Reducing the room air temperature or backward body inclination intensifies the transport of the pollution to the breathing zone and increases personal exposure. The front edge of a table positioned at zero distance from the human body can reduce the pollution transport to the breathing zone, or it can increase transport of the clean air from beneath if positioned at a 10-cm (0.33-ft) distance.

2015

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