Pitch change

Waters (1963) reported on the mixing obtained in wire-wrapped bundles. He found that a increased from 0.1 to 1 as the wrap pitch changed from 0.7 to... 

In spite of the many successes of the phase vocoder, numerous problems have limited its use. In the applications of time-scale modification and compression, for example, it is assumed that only one sine wave enters each bandpass filter within the filter bank. When more than one sine wave enters a bandpass filter, the meaning of the input sine-wave amplitude and phase envelope is lost. A particular sine wave also may not be adequately estimated when it falls between two adjacent filters of the filter bank. In addition, sine waves with rapidly-varying frequency due to large vibrato or fast pitch change are difficult to track. A result of using a fixed filter bank is that the frequency of... 

Helix pitch change change in optical properties due to a change in herix pitch... 

Yamaguchi T, Inagawa T, Nakazumi H, Irie S, Irie M. 2001. Photoinduced pitch changes in chiral nematic liquid crystals formed by doping with chiral diarylethene. J Mater Chem 11(10) 2453 2458. 

T. Yamaguchi, T. Inagawa, H. Nakazumi, S. Irie, M. Irie, Photoswitching of helical twisting power of a chiral diarylethene dopant pitch change in a chiral nematic liquid crystal. Chem. Mater. 12, 869-871 (2000)... 

For mass flow hopper applications, these features limit the effective length of screws that vary in pitch only, to about five or six screw diameters. For non-mass flow applications, pitch changes are a useful means to reduce power and secure an improved extraction pattern, and much longer exposed sections of screws can be used. These benefits may not be essential, but offer advantages by avoiding excessive dead zones of storage. 

While the linearity is thus not a problem, the fact that the periodic pitch changes during switching is a problem. At high tilt this will lead to the appearance of ripples in the homogeneous structure. This is very similar to the instability appearing in the electroclinic switching in the smectic A ... 

When the pitch changes with variation of temperature the colours also change. This phenomenon is used in thermography, a sensitive technique for measurements of the distribution of temperature over various objects, for example, in medicine for making temperature maps of human skin. In technics, cholesterics are used for the estimation of the temperature distribution over plane electrOTiic circuits and other objects with a relatively flat surface. 

Figure 1.13 Schematic diagram showing how the pitch change of a thermochromic cholesteric liquid crystal.

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