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This paper compares the interpolation methods used in network‐based GPS techniques, including the linear combination model, distance‐based linear interpolation method, linear interpolation method, lower‐order surface model, and least‐squares collocation. The advantages and disadvantages of each method are discussed. All of the methods use an n‐1 independent error vector generated from a network of n reference stations to model the distance‐dependent biases at the user station. General formulas for all of the methods involve first computation of the n‐1 coefficients, and then formation of an n‐1 linear combination with an n‐1 error vector from the reference stations to mitigate the spatially correlated errors for the user station(s). Test results from multiple reference stations show that all of the methods can significantly reduce the distance‐dependent biases at the GPS user station. The performance of all the methods is comparable.

Blend films of silk fibrion (SF) and poly(vinyl alcohol) (PVA), with glycerin as an additive, were made, and the structure and properties of the blends were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and wide-angle X-ray diffraction (WAXD) and with an Instron Material Tester. The results showed that SF and PVA are principally incompatible and the blends made by the two polymers were phase-separated. The results, however, also demonstrated that the blend structure could be changed to some extent by addition of 3-8% glycerin. The boundary of the PVA and SF phases became indistinct, as reported by SEM, a new peak appeared in the WAXD curves, the width of the OH absorption peak in the FT-IR spectra increased, and the melting points changed in the DSC curves. In particular, the mechanical properties obviously increased, from 350 kg/cm 2 and 10% of PVA/SF (80/20) film to 832 kg/cm 2 and 39% of PVA/SF (80/20) film because of the increase in glycerin. It was suggested that glycerin plays a role in building the relationship between PVA and SF, strengthening the interaction between them and improving their compatibility.

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