ADVANCED MATERIALS & PROCESSES | MAY/JUNE 2025 26 ore mineralogy and metal smelting debris, provenance studies can produce significant results...” Figure 4 compares Chinese LIA data assemblages for 1st millennium BC Wangdahu burial site bronzes, Upper Xiajiadan copper smelting site ores and slags, and ancient and modern Dajing ores[11]. This example was chosen for its clarity and a comparison between traditional bivariate plots and the more modern kernel density estimate (KDE) method, which uses a probabilistic approach. Figure 4a is a bivariate scatter plot showing that lead (Pb) in the bronzes most likely did not come from ancient Dajing ores and, by inference, from Dajing smelting sites. But some uncertainty is introduced by ore and slag data from the Upper Xiajiadan smelting sites. Figure 4b shows the superposition of KDE probability contour plots on the data assemblages. The KDE contour plots indicate first, that the Upper Xiajiadan smelting site ores and slags are most probably a subset of the Dajing ores data. Second, the kernel distribution for the slags is skewed toward lower values of 206Pb/204Pb. This implies that the smelters may have mixed Dajing ores with other sources that had lower lead isotope ratios[11]. INVASIVE: LOCKHEED MARTIN F-16 WING ATTACHMENT FITTING BOLTS Scheduled inspections at the beginning of July 2007 revealed surface rusting of wing attachment fitting (WAF) steel bolt assemblies in three Royal Netherlands Air Force (RNLAF) F-16 aircraft. See Fig. 5 for a schematic of some of the assemblies (32 per aircraft). Checks showed that these aircraft and 30 others had taken part in a wing modification program, during which all the bolts had been immersed for up to three days in paint stripper. This was a nonapproved cleaning liquid that removed much of the original protective cadmium plating on the bolts. The OEM (Lockheed Martin) responded to the inspection results by designating the entire cohort as suspect and Fig. 2 — Detail of one of the failure-initiating fuse pins (outboard, see Fig. 3, label 3) and the concatenation of damage to the 747-200 Cargo aircraft. Engines 3 and 4 and most of their pylon components detached during flight and were later recovered from a lake. Fig. 3 — Most probable sequence of events leading to loss of engine 3 and its pylon[8,9]. Fig. 4 — Chinese LIA data assemblages: (a) bivariate scatter plot for 1st millennium BC Wangdahu burial site bronzes, Upper Xiajiadan copper smelting site ores and slags, and ancient and modern Dajing ores; (b) superposition of KDE probability contour plots on the data assemblages[11].
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