The behavior of the optimizer is influenced by three key factors: the value of OPTCOMPIND parameter in the Informix configuration file, query directives, and the accuracy of internal statistics.
The result of comparison demonstrates that the device based on internal reflection effect has small size, simple structure and high accuracy and it can be used in the on-line production.
Generally, the internal forces of shells are analysed by the plate elements, but because of the slope discontinuity of internal boundaries, it always influences the accuracy of the solution.