phase problem


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phase problem

[′fāz ‚präb·ləm]
(crystallography)
The problem that arises in determining the electron density function of a crystal from x-ray diffraction data, namely that a complete determination requires knowledge of both the magnitudes and phases of the structure factors, but experimental measurements yield only the magnitudes.
References in periodicals archive ?
This phase problem approach seems to me to have promise, using nanofabrication techniques to create cellular optical device encryption surfaces (or CODES) on the surface of banknotes in order to generate unique optical features which are very difficult to invert or counterfeit--in other words a secure easily recognizable physical one-way function.
The period of the interfering signal that is causing the phase problem can be calculated from this display.
If one could minimize the value of this complicated expression containing thousands of variables, one could solve the phase problem.
In this study, a problem is considered to be a transfer problem if the solution of the problem uses the application of previous knowledge to solve a problem in a new situation, the validators classified them as transfer problems and the items are not similar to the acquisition and evaluation phase problems.
Phase problems and the nature of a proper sound-stage presentation are only part of the ongoing debate about microphones and their placement for two-channel recordings.
Done with skill, multi-microphone use can greatly reduce the kinds of phase problems disliked by the coincident-source proponents, while still allowing the kind of control over the resulting sound mix that some recording engineers can feel comfortable with -- particularly if they have to re-master later on for a DVD-audio version.