AE signal extraction under the strong noise
According to the technology of using acoustic emission signal to extrapolate the acoustic emission source, the multiple signal classification algorithm based on far-field uniform linear array model had been researched in this paper. Combined with the property of AE monitoring, we present that the far-field multiple signal classification algorithm can be applied to estimate the position of the AE signal source. We can basically find the position of the AE signal source by making this algorithm adaptation with roadway shape and workface in the coal mine AE signal detection. The simulation results show that the proposed algorithm could effectively estimate the position of the AE signal source.
Estimation of the Site of Hypocenter and the Magnitude of Seism Based on Array Signal Processing
The first section of this paper presents a new approach to estimate the location and magnitude of seismic origin in the important area and the region suffered frequently from seism.The approach is mathematically analyzed in detail.The notable achieve-ments include the model of realistic lithosphere fabricated with complicated nonuniform transmission media and its shifted simplified al-ternative constructed with uniform transmission media.And then a concrete algorithm is detailed for clarity followed with the simulation results generated by computer.It is easy to find by the new approach people are probably free of the puzzle in locating the hypocenter for the special monitored area.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.