We propose an elliptical sub-aperture stitching (ESAS) method to measure the aspheric surfaces. In our method, the non-null configuration is used to overcome the disadvantages of the null testing. By adding the dynamic tilt, the different local nearly null fringe patterns are obtained and the corresponding phase data in the elliptical masks is extracted with negligible retrace errors. In order to obtain the full aperture result, a stitching algorithm is developed to stitch all the phase data together. We firstly show the principle of our method. Then the performance of the proposed method is analyzed by simulation experiments. In the end, practical examples are given to demonstrate the correctness of the proposed method. The stitching result shows a good agreement with the full-aperture null testing result.
Diethylene glycol (DEG) + H2O solutions (DEGWs) were used as the promising medium for the absorption processes of SO2. In this work, when UV, FTIR,1H NMR, and fluorescence spectroscopic techniques were used for inspection of spectral changes of DEGWs with increasing SO2 concentration, the results suggest that H2O can interact with DEG by hydrogen bonds as the formation of −CH2CH2O(H)...−HOH...− and −CH2−CH2−O(CH2−CH2−)...−HOH...− in DEGWs. Furthermore, SO2 can interact with DEG in various DEGWs by hydrogen bonds as the formation of −CH2CH2OH...−OSO...− and the intermolecular S...−O interaction in the absorption processes of SO2, which was not discussed in the previous similar systems. The results of this work can be used to provide an important absorption mechanism for the design and operation of the absorption and desorption process in flue gas desulfurization with potential industrial application of DEG aqueous solutions.
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