Abstract: A method, which is used to make controlled defects corresponding to natural flaws and residual stresses in various kinds of test pieces. Defects identical to natural flaws are required to qualify non-destructive testing (NDT) procedures. In the method, sequential, repeated, heating-cooling cycles are used to create defects and residual stresses. The shape of the heating and cooling pattern, the duration of the heating and cooling, and the number of thermal cycles are used to control the size of the defects and residual stresses obtained. The defect is grown without initial flaw or other nucleator. The defects correspond to natural flaws in terms of morphology and also of the signals obtained with NDT methods, and are suitable for use in, for example, NDT-qualification blocks.

Abstract: Procedures are provided for analyzing multicomponent FT-IR spectra for unknown mixtures of gases. In the analysis, the FT-IR spectrum is measured for the particular unknown mixture of gases to be analyzed. The operations of the multicomponent analysis are divided into three different levels so that the most laborious operations, which have to be performed very seldom or only once, are on the highest level. Rapid calculation operations to be performed in connection with each spectrum analysis are on the lowest level. The levels are as follows: 1) Forming a spectrum library; 2) Introducing a new basis and adding a new vector to the old basis; and 3) Individual analysis. Variances, error limits, and residual spectrums are calculated in the analysis. A windowing procedure is followed to reject spectrum portions where the transmittance approaches zero or which do not contain real information for some other reason.