Rotational speed

About: Rotational speed is a research topic. Over the lifetime, 23327 publications have been published within this topic receiving 151696 citations. The topic is also known as: speed of revolution & revolution rate.

Variable valve actuation control system

Abstract: In a control system for a valve actuation property variable control device which can switch over between a plurality of modes including a low speed mode for adapting at least one of an intake valve and an exhaust valve of an engine to a low speed range and a high speed mode for adapting the valve to a high speed range at least according to the rotational speed of the engine and a representative temperature of the engine, to prevent an abrupt change in the engine output by switching over valve actuating properties while the engine is being warmed up, the load condition of the engine is detected so that the transition from the low speed mode to the high speed mode may be prohibited if the representative temperature of the engine exceeds a prescribed level while a load higher than a prescribed level is being detected Thereby, the driveability of the engine is improved

Avalanche dynamics of granular materials under the slumping regime in a rotating drum as revealed by speckle visibility spectroscopy

Abstract: We used speckle visibility spectroscopy to measure the time-resolved dynamcis of avalanching down the inclined surface of a granular material in a half-full rotating drum operating in the slumping regime. The distribution of the avalanche period, t(d), rest time between them, t(r), and peak particle velocity fluctuation, δv(p)(2), are all normally distributed. While the distributions of the two times at the top and bottom of the free surface are very similar, the particle velocity fluctuation is greater at the bottom of the free surface than at the top. The rest time is observed to be inversely related to the drum speed. Combining this with the relation of t(r) and the difference of the upper and lower angle of repose for the granular material, Δθ, we find that the latter decreases linearly with increasing rotational speed. We also observe that t(d) increases in a linear fashion with the drum speed. Using the relation of t(r) and the distance that particles have to move during an avalanche, we further find that a new scaling relation of the mean number of avalanches required to traverse the free surface with drum speed. We find that the slumping frequency increases with the rotating speed before becoming constant in the slumping-to-rolling transition region. Finally, we find that the average peak of the fluctuation speed of the avalanche, δv(p)(2), increases linearly with the drum speed.

Process for the early recognition of hydroplaning of a vehicle tire on a wet road

Abstract: The invention provides a process for the advance recognition of the hydroplaning of a vehicle tire on a wet road, in which the rotational speed of the wheel carrying the tire is sensed by a rotational speed sensor and the frequency spectrum of the rotational wheel speed is evaluated. According to the invention, in the frequency range above 20 Hz, the natural resonance behavior of the rotational tire vibrations is evaluated continuously, and a conclusion on hydroplaning of the tire is drawn from detuning of the rotatory natural frequencies.