EDMCAL: Processing EDM calibrations in NSW
The Surveyor General of New South Wales is a verifying authority under the National Measurement Act 1960 and responsible for ensuring that surveyors use verified measuring equipment. According to the Surveying and Spatial Information Regulation 2012, surveyors are required to verify their Electronic Distance Measurement (EDM) equipment in relation to an Australian standard of measurement of length at least once a year. For this purpose, Land and Property Information (LPI) provides and maintains several EDM baselines across the state. LPI is currently in the process of improving this infrastructure by upgrading existing baselines and building new baselines for the calibration of EDM instruments. This paper presents the current status of EDM baseline infrastructure in NSW and outlines the data processing performed by LPI in regards to EDM calibrations. The EDMCAL software currently employed by LPI is described and compared to a spreadsheet calculation generated by the University of New South Wales. Finally, LPI’s new online EDM baseline booking system is introduced. This online system should now be used by surveyors to book access to all EDM baselines in NSW in order to allow efficient and effective use of existing and future baseline infrastructure.
ELECTRONIC DISTANCERS FOR SHORT RANGES: ACCURACY AND CHECKING PROCEDURES
Abstract Since the first infra-red distancers were exhibited in July 1968 at the International Society of Photogrammetry Congress in Lausanne, the electronic distancer has ceased to be regarded by the practising surveyor as a mysterious instrument which could only be used by specialists. There is no doubt that modern electronic distancers can nowadays be used economically for day to day survey work [1]. Since 1968, the number of distancers available for ranges up to 1000 m has increased. Most of these instruments use an infra-red carrier wave with a wavelength of about 0.9 μm, i.e. that portion of the infra-red spectrum next to visible light. The chief reason for using infra-red as a carrier wave is the ease with which the GaAs diode—which is normally used as the source of radiation—can be modulated. Unlike incandescent or gas-discharge lamps, the GaAs-diode can be modulated directly in the high-frequency range by varying its supply current. Other advantages of infra-red radiation with regard to absorptio...
Review of Literature on Probability of Detection for Magnetic Particle Nondestructive Testing
Abstract : A critical review of the available literature concerning the minimum reliably detectable defect size aNDI for magnetic particle testing (MPT) in aerospace applications is presented. Four probability of detection (POD) studies relevant to detection of fatigue cracks in aircraft components were found over the period 1968 to 2011. As the statistical methods used in these four previous studies were either outdated or otherwise deficient, the original data were reanalysed using currently accepted techniques. A meta-analysis of the results is presented, with emphasis on statistical inferences for the defect size expected to be detected with 90% POD. It is shown that the minimum reliably detectable defect size aNDI = 2.0 mm currently specified by the Royal Australian Air Force for wet fluorescent magnetic particle inspection using the continuous method is consistent with estimates of the average performance of MPT derived from the reanalysis of the literature.