Use wear analysis

Olduvay Gorge, Tanzania Fleischer et al. (1965a, 1965b, 1965c) 

The ancient use of lithic tools is generally determined from an analysis of their shape. The latter is frequently assessed by analogy to modern equivalents, or by making experimental replicas and using them for different tasks. 

Use may also be determined by examining the way the tools wore when used and by analyzing residues on their surface. 

The composition of the particles is related to that of the source rocks. Quartz sand [composed of silica (silicon dioxide)], which makes up the most common variety of silica sand, is derived from quartz rocks. Pure quartz is usually almost free of impurities and therefore almost colorless (white). The coloration of some silica sand is due to chemical impurities within the structure of the quartz. The corranon buff, brown, or gray, for example, is caused by small amounts of metallic oxides iron oxide makes the sand buff or brown, whereas manganese dioxide makes it gray. Other minerals that often also occur as sand are calcite, feldspar and obsidian Calcite (composed of calcium carbonate), is generally derived from weathered limestone or broken shells or coral feldspar is an igneous rock of complex composition, and obsidian is a natural glass derived from the lava erupting from volcanoes see Chapter 2. 

Throughout the ages humans have used sand for many and the most varied uses. Some river sand, known as auriferous sand, contains native gold 

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Hayden, B. (ed.) (1979), Lithic Use-Wear Analysis, Academic Press, London. 

Hurcombe, L. (1992), Use - Wear Analysis and Obsidian Theory, Experiment and Results, Collis, Sheffield. 

Vaughan, P. (1985), Use-Wear Analysis of Flaked Stone Tools, Univ. Arizona Press, Tucson. 

Other studies on stones beyond identification and provenience studies include microscopic studies of use-wear and analysis of possible residues for DNA or other, biologically distinctive organic molecules, which will be separately discussed in a later section. 

Stemp, W.J., B.E. Childs, S. Vionnet, and C.A. Brown. 2008. Quantification and discrimination of lithic use-wear surface profile measurements and length-scale fractal analysis. Archaeometry XXX. 

SIMS has proved to be a very useful tool in polymer film studied and accordingly wear analysis. Various polymers have been fingerprinted with SIMS including in addition to those already discussed, low density polyethylene, polypropylene, polystyrene, nylon-6 and polyethylene terephthalate (8,9). 

Some assessors also do a useful life analysis to provide the safety instrumentation engineer with knowledge of any wear out mechanisms and the time periods imtil wear out. Preventative maintenance programs can be established to replace instruments at the end of their useful life knowing this information. Some FMEDA analyses are also extended to evaluate the effectiveness of proposed proof test methods. This provides the safety instrument engineer with proof test coverage factors used for more realistic PFH/PFD/PFDavg calculations. 

As we discussed in introduction, the field return data can not be used for analysis of the wear out region since electronic boards get into this region long after their warranties expire. Therefore, we only deal with early failure and useful time periods. We develop our hazard rate function with phases having Decreasing Failure/Hazard Rate (DFR) and Constant Failure Rate (CFR) like those proposed by Yuan et al. (2010) and Chen et al. (1999). Here, DFR and CFR correspond to early failure and useful hfe regions, respectively. The proposed overall hazard rate function h it) is presented in Equation 1 where h i) = hazard rate function in early failure period, h ii) = hazard rate function in useful-life period, t = time (TTF), and X = change point from DFR to CFR. 

The goal of using radiographic analysis techniques to measure wear in total hip arthroplasty has changed over time. Originally, they were used to correlate the amount of femoral head penetration with the incidence of periprosthetic osteolysis. This association is now well established and irrefutable. New bearing materials, such as... 

Using the analysis from a white hght interferometer (Zygo New View 5000-3D), it was possible to obtain volume losses and calculate the dimensionless wear coefficient values of K using the Archard equation 1 [3] where V is volume loss, H hardness, Wload and L sliding distance. 

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