Results 261 to 270 of about 203,397 (298)

Higher Harmonic Rotor Control

Aircraft Engineering and Aerospace Technology, 1958
The elimination of the retreating blade stall speed limitation for helicopters by means of an appropriately programmed feathering input is studied for the general case of a rigid flapping blade with hinge constraint (thus making the results applicable to conventional, offset‐hinged or cantilevered rotor blades).
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Higher Harmonic Control ­ A Historical Perspective

Proceedings of the Vertical Flight Society 74th Annual Forum, 2018
Higher Harmonic Control (HHC) is an approach for achieving reduced helicopter vibration by controlling the vibratory rotor airloads in such a way that the fuselage excitation is minimized. This paper is a historical look at how a program aimed at helicopter vibration reduction started as an outgrowth of fixed wing flutter suppression at NASA ...
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Deriving Harmonic Functions in Higher Dimensional Spaces

Zeitschrift für Analysis und ihre Anwendungen, 2003
For a harmonic function, by replacing its variables with norms of vectors in some multi-dimensional spaces, we may induce a new function in a higher dimensional space. We show that, after applying to it a certain power of the Laplacian, we obtain a new harmonic function in the higher dimensional space. We show that Poisson and Cauchy kernels and Newton
Qian, T., Sommen, F.
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Spatial waveform discrimination following higher-harmonic adaptation

Journal of the Optical Society of America A, 1988
Campbell and Robson [J. Physiol. (London) 197, 551 (1968)] proposed that a near-threshold square-wave grating can be distinguished from a sine-wave grating of the same spatial frequency and fundamental amplitude when the channel tuned to the third-harmonic component of the square wave reaches its own threshold.
M W, Greenlee, S, Magnussen
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Moiré and higher grating harmonics

Journal of the Optical Society of America, 1975
The conditions for and formation of low-spatial-frequency beat patterns between superposed grid structures are studied. The application of moire techniques for Fourier analysis of incoherently illuminated distributions is demonstrated. The different multiples of the fundamental spatial frequency of a grating are used to form distinguishable moire ...
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Nonlinear Impedances (Higher Harmonics)

2013
When linear electrical elements are used in circuits, the measured impedances are independent of the amplitude of the ac perturbation. However, in electrochemistry, the electrical equivalent parameters related to the kinetics, diffusion, and other aspects are nonlinear because the current is a nonlinear function of the applied potential. In such cases,
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Moiré fringes of higher-order harmonics versus higher-order moiré patterns

Applied Optics, 2018
This work presents a very simple and comprehensive approach for classification of the combinational spatial frequencies of the superimposed periodic or quasi-periodic structures. The reciprocal vectors of the structures are used to express their respective spectral components, and a unique reciprocal vectors equation is introduced for presenting the ...
Mohammad Yeganeh, Saifollah Rasouli
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Scatter at Higher Harmonics

2001
The oscillation of gas bubbles is known to be highly nonlinear for moderate driving pressure amplitudes [87]. “Moderate amplitude” means amplitude between 100 and 500 kPa, amplitudes that occur frequently in diagnostic ultrasound imaging. The nonlinear oscillations cause the bubbles to radiate sound at harmonics of the driving acoustic pressure pulse.
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Squeezing by multiple higher-harmonic generation

Czechoslovak Journal of Physics, 1987
It is shown that by generating higher harmonic in a cascade of thin nonlinear plates and filtering out the generated harmonic behind each plate, considerable squeezing in the fundamental mode occurs. The multiple higher-harmonic generation processes are aimed to simulate ideal multi-photon absorbers without undesirable lower-order absorption and ...
P. Chmela, M. Kozierowski, S. Kielich
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Decomposing magnetic fields into their higher harmonics

Proceedings of the American Institute of Electrical Engineers, 1915
When it is necessary to decompose a magnetic field into its higher harmonics the same methods used for analyzing current and voltage waves may be employed. In many cases, however, the usual long mathematical operations can be avoided by representing the field shapes as geometrical figures, such as triangles, rectangles, trapezoids, etc., all of which ...
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