Calibration curve

About: Calibration curve is a research topic. Over the lifetime, 6552 publications have been published within this topic receiving 95128 citations.

High accuracy particle dimension measurement system

Abstract: A measurement tool connects to an automatic inspection machine for identifying and measuring microscopic dimensions such as area, diameter, height and line width of defects and lines of a photographic mask An operator draws a rough region of interest around a feature and the tool automatically identifies the feature and calculates its dimensions For features less than one micron in size, the size of light photons interferes with measurement, so a non-linear polynomial calibration curve is developed for each machine Features of known sizes are measured on a production machine to produce a calibration curve for each type of defect or line Features of unknown sizes are measured on the same machine and the measured size in pixels are calibrated using the calibration curve to return a more accurate reading in microns To determine a dimension, the type of a feature is determined by using a bounding box and light transitions of an intensity profile of the feature; multiple regions of interest are developed for each feature to accommodate angled lines; columns of pixels in each region of interest are summed to produce a light intensity distribution profile for each region of interest; total flux is determined from each profile and the best flux measurement is used to calculate a dimension of the feature A good image of a feature is obtained by subtracting a reference image from an original image if a profile is of low quality For lines separated by less than one resolution unit, a fall-width half-maximum technique is used to calculate line width

On-Site Quantitative Elemental Analysis of Metal Ions in Aqueous Solutions by Underwater Laser-Induced Breakdown Spectroscopy Combined with Electrodeposition under Controlled Potential

Abstract: We propose a technique of on-site quantitative analysis of Zn2+ in aqueous solution based on the combination of electrodeposition for preconcentration of Zn onto a Cu electrode and successive underwater laser-induced breakdown spectroscopy (underwater LIBS) of the electrode surface under electrochemically controlled potential. Zinc emission lines are observed with the present technique for a Zn2+ concentration of 5 ppm. It is roughly estimated that the overall sensitivity over 10 000 times higher is achieved by the preconcentration. Although underwater LIBS suffers from the spectral deformation due to the dense plasma confined in water and also from serious shot-to-shot fluctuations, a linear calibration curve with a coefficient of determination R2 of 0.974 is obtained in the range of 5–50 ppm.

A Direct J-R Curve Analysis of Fracture Toughness Tests

Abstract: A method is proposed to evaluate fracture toughness in a J-R curve format directly from load displacement records without the need for automatic crack length measurement devices. This method uses the calibration curve in which the flow properties of a material for a stationary crack provide the relationships between load, displacement, and crack length. Crack growth is then evaluated by comparing load and displacement pairs for the growing crack case with this stationary crack curve. This is similar to the approach in which a common “key curve” was used to determine crack length; however, in this case, individual calibration curves are developed for each specimen. The calibration curve is described by separate elastic and plastic components of displacement. The relationship between load and elastic displacement is described by a compliance function and between load and plastic displacement by a power term with constant coefficient and exponent. Three methods are suggested for evaluating the power term exponent and coefficient. The first assumes that the exponent coming from a fit of the true-stress true-strain tensile test results can be used, the second determines all information directly from the test record, and a third does the same but uses a plastic zone adjustment. The method is applied to a set of results from an A508 steel in which the J-R curve had previously been determined using the elastic compliance method of crack length measurement. These tests were conducted on compact specimens with a range of sizes varying by a factor of 20 (10T to 1/2T). The method is also applied to a 4340 steel and stainless steel weld metal. The results show that second approach works best. Although further evaluation of the method is needed, it showed promise as a replacement for automatic crack length measurement techniques in the evaluation of J-R curves.

Advances in second-order calibration

Abstract: Several multivariate methods are now available for the calibration of second-order or hyphenated instruments (e.g. GC/MS). When applied to bilinear data, it has been shown that calibration can be performed in the presence of unknown interferences - a significant advantage over first-order calibration. In this paper, non-bilinear rank annihilation (NBRA), a method which has the potential of handling, second-order non-bi-linear data, is studied through theoretical analysis and computer simulation. It is found that the second-order advantage can be carried over to non-bilinear data if a property defined as net analyte rank (NAR) holds for the analyte of interest. The net analyte signal (NAS) is defined accordingly for second-order calibration and the analogy to and difference from lower-order calibration are discussed. With NAS, some analytical figures of merit such as signal-to noise ratio, selectivity, sensitivity and limit of determination can be calculated for second order calibration. An application to MS/MS data is also given.