Course de fond

Résumé

La course de fond ou course longue distance ou encore course d'endurance désigne la course à pied sur une distance d'au moins . Physiologiquement, c'est un effort impliquant principalement un processus métabolique d'aérobie (production d'énergie par consommation d'oxygène) et qui requiert des capacités physiques d'endurance. Parmi les mammifères, les humains sont bien adaptés à la course sur longue distance, à l'opposé des autres primates. Une hypothèse scientifique suggère que la course d'endurance serait apparue dans le genre Homo parce que le déplacement sur de grandes distances améliorait les chances de trouver des charognes et permettait la chasse à l'épuisement. Cette capacité de course d'endurance se retrouve aussi chez les ongulés migrateurs et un petit nombre de carnivores terrestres, tels que chien, loup et hyène. Dans la société moderne, la course longue distance a de multiples usages : elle peut être pratiquée comme exercice physique, loisir, manière de voyager. Elle p

Source officielle

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

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Publications associées (31)

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Cours associés (24)

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Séances de cours associées (42)

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Nowadays the methods of design, planning and managing of integrated energetic systems which allow an overall view of all possibilities are still embryonic. However, this first phase of the design is crucial if we want to aim at a better resources management and at the decrease of energy consumption togheter with reduced pollution. Dealing with energetic energy integrated systems implies dealing with complex systems exploiting the synergy between the various components (for example the thermal energy of a diesel engine produced during the night is valorised by the Rankine Organic Cycle of a solar thermal plant). The context of the isolated communities further increases the difficulties and the needs for a more rational energy use considering the long distance of transportation linked to the supply of fossil fuels. These sites are often located in very precarious environments, with limited or inexistent resources, and with additional requirements for desalination (arid zones). ...........

2004

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Measurement of the inner structure of turbidity currents by ultrasound velocity profiling

Jumpei Hitomi, Shun Nomura

The inner velocity structure and particle concentration profile of opaque turbidity currents were mea- sured simultaneously by ultrasound velocity profilers. Currents consisting of a quartz particle suspension were generated by using the lock-exchange method in a flume to experimentally reproduce the quasi- steady state of a turbidity current. A pair of ultrasound transducers captured the horizontal and vertical velocities from Doppler frequencies, and the particle concentration profile was extracted from the echo amplitude. The data obtained were analyzed in terms of momentum conservation according to the two- fluid model. We found that: i) the viscous and Reynolds shear stresses balance in the top half of the current; and ii) the lower border of the stress balancing appears around the depth of the maximum ver- tical density gradient. These findings indicate that the reduction of flow resistance inside the body region of the turbidity current is maintained downstream, which enables the current to transport particles over a long distance.

2021

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Steady state in experimentally produced turbidity current under a large amount of suspension supply

Giovanni De Cesare, Jumpei Hitomi, Shun Nomura

Turbidity current is generated in an inclined lock-gate flume under a large amount of suspension supply. By opening the gate, turbidity current generates and flows to downstream. The turbidity current maintains its interface structure and progresses with constant frontal velocity. The inner velocity profile of the quasi-steady body by ultrasound velocity profiler (UVP) falls on the similar convex lines within the fluctuations in space and time. We conclude that turbidity current progresses in a steady state flow structure with small dissipation, which is a key to transport a large amount of sediment in a long distance.

2019

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