Ethanol-sensing properties of potassium bromide/multi-walled carbon nanotube composites

The work reported in this paper is related to the fabrication and electrical characterization of multi-walled carbon nanotubes (MWNT)-based solid composites pellets with potential application as gas sensor at room temperature, using potassium bromide as supporting material. Results show an electrical conductivity of the composites as a function of the MWNT loading following a power law associated with a percolation phenomenon. A variation of the electrical resistance of the composites as a function of ethanol concentration in a nitrogen atmosphere has also been observed, allowing detection of ethanol from about hundred of ppm. It is also shown the existence of an optimal MWNT loading for which the composite reaches its best ethanol-sensing performances.     

Novel CMM-based implementation of the multi-step method for the separation of machine and probe errors

Coordinate measuring machines (CMMs) are subject to periodic verification to ensure measurement capability. However, users also need to rapidly diagnose the source of accuracy degradation to guide corrective actions. This paper presents a novel CMM-based implementation of the multi-step method for the separation of machine and reference sphere errors on one side and triggering probe and probe tip errors on the other. The procedure uses multiple redundancy probing of the machine's own reference sphere and result in a mathematical system similar to that of the multi-step method. The procedure's effectiveness is demonstrated for a variety of stylus lengths and shows its ability to detect changes in lobing errors. A metrological validation is conducted by measuring the errors of the probe and errors of the machine using independent methods.