Low voltage AC-DC transfer standards at LNE
This paper describes the method used to establish the traceability of LNE AC-DC transfer standards in the mV-range to the 1 V multijunction converter, which serves as the primary AC-DC standard. Main uncertainty components are listed and final uncertainty given for the different voltage levels. An independent method was developed for the calibration of thermal converters at 0.3 V and 0.2 V. The agreement between this method and the step-down is within the standard uncertainty.
Automated comparator for accurate AC-DC difference measurements at the BNM-LCIE
This paper describes the new automated comparator system developed at the BNM-LCIE for the calibration of voltage thermal converters used as national AC-DC transfer standards. The system achieves Type A standard uncertainties of a few parts in 10/sup 7/ in the frequency range from 10 Hz to 1 MHz (100 kHz for voltages above 100 V). Type B standard uncertainties, depending on the type of converters to be compared and on the measurement voltage level, are between a few parts in 10/sup 7/ and a few parts in 10/sup 6/.
Concentrated solar energy in materials processing
Solar energy, which is available in abundant in nature, is least utilised. As per primary energy product, solar energy conversion can be of three different ways: solar fuels, solar electricity, and solar thermal systems. These three approaches are presently not being fully utilised. Concentrated solar energy (CSE) is an alternative to other types of energy for modifying the surfaces of metallic materials. Attempt has been made to overview the current status of CSE in materials processing technology. In this paper, applications of CSE through solar furnace and Fresnel lens for hardening, coatings, sintering, nitriding, synthesis and welding are discussed.