Topic
Fundamental frequency
About: Fundamental frequency is a research topic. Over the lifetime, 8941 publications have been published within this topic receiving 131583 citations.
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17 Jul 1989
TL;DR: In this paper, a method and apparatus for improving the performance of polyphase AC machines is presented, where the fundamental flux wave and the harmonic flux wave will travel at synchronous speed in the air gap.
Abstract: A method and apparatus for improving the performance of polyphase AC machines. The polyphase AC machines are excited both with a fundamental frequency and with an odd harmonic of the fundamental frequency. The fundamental flux wave and the harmonic flux wave will travel at synchronous speed in the air gap. This facilitates redistributing the flux densities in the machine and thereby increasing the total flux per pole in the machine.
59 citations
TL;DR: In this paper, the exact solution and some approximate solutions for the free vibrations of uniform rectangular curved panels with simply supported edges are given Exact solutions are not available for all boundary conditions and a general energy method, in which the mid surface displacements are represented by truncated double-power series in the mid-surface co-ordinates of the panel, is outlined.
59 citations
TL;DR: A tuning fork vibrating in its fundamental mode is approximately a linear quadrupole sound source whose strength can be increased by use of a baffle or by touching the stem to a soundboard as mentioned in this paper.
Abstract: Tuning forks can vibrate in many different modes in which the tines move either in the plane or perpendicular to the plane of the fork. Symmetrical modes can be modeled by the motion of two cantilever beams, antisymmetrical modes by the motion of a beam with free ends. A tuning fork vibrating in its fundamental mode is approximately a linear quadrupole sound source whose strength can be increased by use of a baffle or by touching the stem to a soundboard. The motion of the stem includes strong components at both the fundamental frequency and its second harmonic. Slight alterations in a tuning fork can enhance or suppress either of these components. At large amplitudes, the tines vibrate nonsinusoidally, the nth harmonic increasing approximately as the nth power of the fundamental.
59 citations
21 Jun 2011
TL;DR: Fluctuations of the frictional force arising from the stroke of a finger against flat and sinusoidal surfaces are studied and are consistent with the existence of a multiplicity of simultaneous and rapid stick-slip relaxation oscillations.
Abstract: Fluctuations of the frictional force arising from the stroke of a finger against flat and sinusoidal surfaces are studied A custom-made high-resolution friction force sensor, able to resolve milli-newton forces, was used to record those fluctuations as well as the net, low-frequency components of the interaction force Measurements show that the fluctuations of the sliding force are highly non-stationary Despite their randomness, force spectra averages reveal regularities With a smooth, flat, but not mirror-finish, surface the background noise follows a 1/f trend Recordings made with pure-tone sinusoidal gratings reveal complexities in the interaction between a finger and a surface The fundamental frequency is driven by the periodicity of the gratings and harmonics follow a non-integer power-law decay that suggests strong nonlinearities in the fingertip interaction The results are consistent with the existence of a multiplicity of simultaneous and rapid stick-slip relaxation oscillations Results have implications for high fidelity haptic rendering and biotribology
59 citations
TL;DR: In this paper, the authors further explored how frequencies vary during a vehicle passage and empirically showed that the frequency shift depends also on the vehicle-to-bridge frequency ratio, and the results confirmed different frequency shifts for vehicles with the same mass but different suspension properties.
59 citations