Topic
Harmonic
About: Harmonic is a research topic. Over the lifetime, 44833 publications have been published within this topic receiving 495922 citations. The topic is also known as: overtone & partial.
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TL;DR: In this paper, the linearized water wave theory is used to show that a submerged long circular cylinder suitably constrained by springs and dampers to make small harmonic oscillations, can be extremely efficient in absorbing the energy in an incident regular wave whose crests are parallel to the axis of the cylinder.
110 citations
TL;DR: In this paper, the periodic response of an oscillating system supported on a frictional interface was studied and the most fundamental periodic solutions were derived analytically and numerically, and it was shown that such a system has several subharmonic resonant frequencies and that while the friction reduces the peak response of the system when it is excited at its "fixed-base" natural frequency, w, the sliding can induce considerably higher levels of response, when compared with those of a non-sliding, fixed-base system, for frequencies less than w,.
Abstract: SUMMARY This paper deals with the periodic response of an oscillating system which is supported on a frictional interface. The base excitation is assumed harmonic and the frictional force is assumed to be of the Coulomb type. Though each segment of the motion of such a system is described by linear equations, its complete response is highly non-linear and varied. The most fundamental periodic solutions are derived analytically and numerically. The results indicate that such a system has several subharmonic resonant frequencies and that while the friction reduces the peak response of the system when it is excited at its ‘fixed-base’ natural frequency, w,, the sliding can induce considerably higher levels of response, when compared with those of a non-sliding, fixed-base system, for frequencies less than w,. The results obtained herein may find application in the area of vibration isolation.
110 citations
TL;DR: The analytical model could be employed to assess the influencing factors of current harmonics and offers insightful guidance to the effective reductions of harmonic losses, torque ripples, and electromagnetic noises.
Abstract: The sideband current harmonic components would inhere in permanent-magnet (PM) synchronous machine systems driven by a voltage-source inverter with space vector pulsewidth modulation (SVPWM). However, these harmonics could potentially deteriorate the overall performance of the drive system by increasing the resultant losses, torque ripple, and electromagnetic and acoustic noises. The main sideband harmonic voltages and currents in PM synchronous machine driven by voltage-source inverter with SVPWM technique, are analytically derived and expressed in both stator and rotor frame. The experimental results are carried out to underpin the validity of the analytical model. The analytical model could be employed to assess the influencing factors of current harmonics. In addition, it offers insightful guidance to the effective reductions of harmonic losses, torque ripples, and electromagnetic noises.
110 citations
TL;DR: This paper investigating the three-dimensional evolution of harmonic radiation based on the coupled Maxwell-Klimontovich equations that take into account nonlinear harmonic interactions finds that the gain length, transverse profile, and temporal structure of the first few harmonics are eventually governed by those of the fundamental.
Abstract: In a high-gain free-electron laser (FEL) employing a planar undulator, strong bunching at the fundamental wavelength can drive substantial bunching and power levels at the harmonic frequencies. In this paper we investigate the three-dimensional evolution of harmonic radiation based on the coupled Maxwell-Klimontovich equations that take into account nonlinear harmonic interactions. Each harmonic field is a sum of a linear amplification term and a term driven by nonlinear harmonic interactions. After a certain stage of exponential growth, the dominant nonlinear term is determined by interactions of the lower nonlinear harmonics and the fundamental radiation. As a result, the gain length, transverse profile, and temporal structure of the first few harmonics are eventually governed by those of the fundamental. Transversely coherent third-harmonic radiation power is found to approach 1% of the fundamental power level for current high-gain FEL projects.
110 citations
TL;DR: This paper represents Part I of a two-part article which summarizes the probabilistic aspects of harmonics in electric distribution systems and various ways to describe recorded data in statistical terms.
Abstract: This paper represents Part I of a two-part article which summarizes the probabilistic aspects of harmonics in electric distribution systems. This first part reviews the problems associated with direct application of the fast Fourier transform to compute harmonic levels of nonsteady state distorted waveforms, and various ways to describe recorded data in statistical terms. Each statistical description is applied to a set of recorded data for illustration purposes.
110 citations