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Inline inspection tools that are used to scan the interior defects of gas and oil pipelines tend to suffer from measuring error due to their sizing accuracy. This error often causes an over- or under-estimation of the operating conditions of the pipeline, which might lead to a system failure. While parametric calibration models provide a simple method to reduce the measuring error, it is limited to datasets that follow the normal distribution only. Thus, in this paper, a nonparametric calibration model based on k-nearest neighbor interpolation was proposed to improve the measurements recorded by the scanning tools. Corrosion data collected using an ultrasonic scan device and the magnetic flux leakage intelligent pig are considered in the research. The k-nearest neighbor interpolation is studied based on the effect of using six kernel functions with two different positioning approaches on the interpolation behavior. The results have shown enhancement in the accuracy of the readings obtained from the intelligent pig from ±20% of the pipeline wall thickness to only ±8%. This enhancement in the sizing accuracy is meant to prevent a possible system failure for using the corroded part of the studied pipeline for an extra 4.6 years instead of replacing it. [ABSTRACT FROM AUTHOR]

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The influence of particle morphology on the accuracy of nanoparticle size distributions measured by the engine exhaust particle sizer spectrometer (EEPS, TSI Model 3090) was studied using the scanning mobility particle sizer (SMPS, TSI Model 3936) as a reference. The EEPS shows higher total number concentrations with the maximum relative difference up to 67 % and smaller number median mobility diameters for polydisperse silver nanoparticles generated in the laboratory. To provide a quantitative explanation of the difference, generated polydisperse nanoparticles were classified as monodisperse particles with the initial equivalent mobility diameter ( d) and sintered in the second furnace at different temperatures (room temperature to 600 °C), to change their morphologies for the comparison tests. Without sintering (room temperature), results show that the measured mobility diameter ( d) of the EEPS is smaller than that measured by the SMPS when d is larger than 30 nm and the difference increases as d is increased from 30 to 300 nm. But the difference decreases as the morphology of particles is changed from branched chain agglomerates to spheres for d less than 80 nm and the sintering temperature higher than 200 °C. Theoretical analysis shows that the mean charge per agglomerates is more than that of spheres resulting in overestimation of the electrical mobility and underestimation of the d by the EEPS. [ABSTRACT FROM AUTHOR]