Horizontal positional accuracy of Google Earth's imagery over rural areas: a study case in Tamaulipas, Mexico

Due to the popularity of Google Earth (GE), users commonly assume that it is a credible and accurate source of information. Consequently, GE's imagery is frequently used in scientific and others projects. However, Google states that data available in their geographic products are only approximations and, therefore, their accuracy is not officially documented. In this paper, the horizontal positional accuracy of GE's imagery is assessed by means of comparing coordinates extracted from a rural cadastral database against coordinates extracted from well-defined and inferred check points in GE's imagery. The results suggest that if a large number of well-defined points are extracted from areas of high resolution imagery, GE's imagery over rural areas meets the horizontal accuracy requirements of the ASPRS for the production of "Class 1" 1:20,000 maps. Nonetheless, the results also show that georegistration and large horizontal errors occur in GE's imagery. Consequently, despite its overall horizontal positional accuracy, coordinates extracted from GE's imagery should be used with caution

The Effects of Chemistry Variations in New Nickel-Based Superalloys for Industrial Gas Turbine Applications

Industrial gas turbines (IGT) require novel single-crystal superalloys with demonstrably superior corrosion resistance to those used for aerospace applications and thus higher Cr contents. Multi-scale modeling approaches are aiding in the design of new alloy grades; however, the CALPHAD databases on which these rely remain unproven in this composition regime. A set of trial nickel-based superalloys for IGT blades is investigated, with carefully designed chemistries which isolate the influence of individual additions. Results from an extensive experimental characterization campaign are compared with CALPHAD predictions. Insights gained from this study are used to derive guidelines for optimized gas turbine alloy design and to gauge the reliability of the CALPHAD databases