Danilo Quagliotti

A finite element analysis of surface-stress effects on measurement of the Si lattice parameter

A stress exists in solid surfaces even if the underlying bulk material is stress-free. This paper investigates the effect of surface stress on the value of the Si lattice parameter measured by combined x-ray and optical interferometry. An elastic-film model has been used to provide a surface load in a finite element model on the x-ray interferometer crystal. Eventually, an interferometer design is proposed to determine a measurement where the effect of the surface stress is deemed to be detected.

Stray capacitances in the watt balance operation: electrostatic forces

In a watt balance, stray capacitances exist between the coil and the magnet. Since the electric current flowing in the coil creates a difference in electric potentials between the coil and magnet, their electrostatic interactions must be taken into account. This paper reports the results of a finite element analysis of the forces acting on the coil.

Correction of systematic behaviour in topographical surface analysis

(14/12/2018) Correction of systematic behaviour in topographical surface analysis Four specimens in the sub-micrometre range and with different polishing were topographically investigated in fiveareas over their respective surfaces. Uncertainties were evaluated with and without correction for systematicbehaviour and successively analysed by a design of experiment (DOE). Results showed that the correction forsystematic behaviour allowed for a lower value of the estimated uncertainty when the correction was adequate tocompletely recognise the systematic effects. If not, the correction can produce an overestimation of the uncertainty.