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Calibration curve
About: Calibration curve is a research topic. Over the lifetime, 6552 publications have been published within this topic receiving 95128 citations.
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01 Dec 1985-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, K and L line calibration has been performed for a PIXE setup by the independent use of experimental and theoretical methods using thin film standards of known thicknesses, while in the latter one cross section values were derived from different theoretical models.
Abstract: K and L line calibration has been performed for a PIXE setup by the independent use of experimental and theoretical methods. In the former case, thin film standards of known thicknesses were applied, while in the latter one cross section values were derived from different theoretical models. Programs REV5S and PIXEKL developed here were used for spectrum evaluation and concentration determination, respectively. They proved to be reliable and especially appropriate for routine serial evaluation of spectra measured on samples of nearly identical matrices. As a result of the work, an accurate calibration of the setup has been obtained and it was shown that experimental and theoretical techniques used lead to calibration curves which fit each other reasonably well.
56 citations
TL;DR: In this paper, the uncertainty of results gained through the two commonly used, but quite different, calibration methods (DOAS and calibration cells) is investigated with three different instruments, an SO2 camera, a NFOV-DOAS system, and an Imaging DOAS (I-DoAS), where the measurements presented in this work were taken at Popocatepetl, Mexico, between 1 March 2011 and 4 March 2011.
Abstract: . Sulphur dioxide emission rate measurements are an important tool for volcanic monitoring and eruption risk assessment. The SO2 camera technique remotely measures volcanic emissions by analysing the ultraviolet absorption of SO2 in a narrow spectral window between 300 and 320 nm using solar radiation scattered in the atmosphere. The SO2 absorption is selectively detected by mounting band-pass interference filters in front of a two-dimensional, UV-sensitive CCD detector. One important step for correct SO2 emission rate measurements that can be compared with other measurement techniques is a correct calibration. This requires conversion from the measured optical density to the desired SO2 column density (CD). The conversion factor is most commonly determined by inserting quartz cells (cuvettes) with known amounts of SO2 into the light path. Another calibration method uses an additional narrow field-of-view Differential Optical Absorption Spectroscopy system (NFOV-DOAS), which measures the column density simultaneously in a small area of the camera's field-of-view. This procedure combines the very good spatial and temporal resolution of the SO2 camera technique with the more accurate column densities obtainable from DOAS measurements. This work investigates the uncertainty of results gained through the two commonly used, but quite different, calibration methods (DOAS and calibration cells). Measurements with three different instruments, an SO2 camera, a NFOV-DOAS system and an Imaging DOAS (I-DOAS), are presented. We compare the calibration-cell approach with the calibration from the NFOV-DOAS system. The respective results are compared with measurements from an I-DOAS to verify the calibration curve over the spatial extent of the image. The results show that calibration cells, while working fine in some cases, can lead to an overestimation of the SO2 CD by up to 60% compared with CDs from the DOAS measurements. Besides these errors of calibration, radiative transfer effects (e.g. light dilution, multiple scattering) can significantly influence the results of both instrument types. The measurements presented in this work were taken at Popocatepetl, Mexico, between 1 March 2011 and 4 March 2011. Average SO2 emission rates between 4.00 and 14.34 kg s−1 were observed.
56 citations
TL;DR: In this paper, a laser-induced breakdown spectroscopy (LIBS) is used for measuring the concentration of cement ingredient in a cement powder and a microplasma is formed in the front of samples.
56 citations
TL;DR: In this article, the calibration curves for a TDR (Time Domain Reflectometry) equipment using five soils from the Piracicaba, SP, Brazil, have been obtained.
Abstract: The aim of this study was to obtain the calibration curves for a TDR (Time Domain Reflectometry) equipment using five soils from the Piracicaba, SP, Brazil. The suitability of the built-in and generic calibration curves was also tested. Individual fitted curves for each soil showed determination coefficients (R2) of about 0.99 and the fitted curve for all five soils together showed a value of R2 = 0.976. The standard error of estimate analysis has pointed out that generic curves are not suitable for more sensible applications, such as for absolute determination of soil water content. Comparison tests among fitted curves, generic curve and the equipment curve, pointed out that the first one is superior to the others. This study showed also that the equipment built-in calibration curve is not suitable for soil water content determinations for the five studied soils.
56 citations
TL;DR: In this article, the functional relationship describing the mixing of the suspension in the tank is expressed in a dimensionless form, and the relationship between the actual and the measured concentration is shown to be linear.
Abstract: Many plots for soil loss measurements are equipped with a sequence of tanks for measuring runoff volume and sediment concentration. The stored water volume is easily determined by a water depth measurement while the sediment concentration is often measured by collecting samples of the mixed suspension. In this paper, using the Π-theorem of dimensional analysis, the functional relationship describing the mixing of the suspension in the tank is expressed in a dimensionless form. The recognized dimensionless groups allow the establishment, for given soil and water depth in the tank, of the relationship (calibration curve) between the actual and the measured concentration. The calibration curve, using measured concentration values obtained from sampling taps located at different heights on the vertical of a tank wall, is shown to be linear. For a given soil, the slope of the calibration curve is related to the water depth. We also show that the same dimensionless groups allow the deduction of a scale-up procedure and the possibility of using a small tank, similar to the field one, for investigating additional effects neglected in the theoretical analysis. The effects of the following factors on the calibration curve are examined: (1) sampling direction along the vertical, i.e. starting the sampling from the upper tap to the lower one or vice versa; (2) mathematical shape of the concentration profile; (3) representativeness of the calibration cufve; (4) sampling volume; (5) water depth into the tank (i.e. filling level); (6) suspension mixing time; (7) grain size distribution of the eroded soil particles for given soil type; (8) time between the end of the erosive event and the starting of the sampling procedure (delay time). Finally, an attempt is made to define a simpler sampling procedure based on a single measurement with a dipped sampler. Copyright © 1998 John Wiley & Sons, Ltd.
56 citations