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The international standard ISO 11843 specifies basic methods to design experiments for estimation of critical values referring to the capability of detection. The detection capability depends on the experimental design, the calibr...
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The international standard ISO 11843 specifies basic methods to design experiments for estimation of critical values referring to the capability of detection. The detection capability depends on the experimental design, the calibration model used, and the errors of the measurement process. This study reports how the specification of the calibration points within the calibration range can be used as a-priori information for evaluation of calibration uncertainty without any consideration of the response variables of the calibration. As result of investigation of the experimental designs, calibration points within the calibration range can be omitted without significant changes of calibration uncertainty. The approach is demonstrated at a practical example, the determination of arsenic in surface water samples taken from a river in Germany.
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Calibration is a technique that adjusts the initial sample on margins that are supposed known for the whole population. Its basic idea consists of using the auxiliary information not taken into account during the sampling design, ...
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Calibration is a technique that adjusts the initial sample on margins that are supposed known for the whole population. Its basic idea consists of using the auxiliary information not taken into account during the sampling design, in order to increase the precision of the Horvitz and Thompson estimator. However, the improvement provided by the calibration estimator depends on the choice of the auxiliary variables as well as their number. In fact, the variance of the calibration estimator may increase very much when a huge number of auxiliary variables are used or when there is a strong multicollinearity. For this reason, some solutions have been proposed in the literature: the Principal Component calibration and the Ridge calibration. Through this paper we propose a new technique named the Partial Least Squares calibration (PLS calibration) that allows to avoid the multiollinearity problem. To show the effectiveness of our method in comparison with the Ridge calibration and the PC calibration, we applied the three methods on a data provided by Marocmetrie a Morrocan company specialized on TV audience measurement.
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A criticalview of univariate calibration techniques developed in the flow injection analysis (FIA) is presented.A classification system based on three main calibration categories-interpolative,extrapolative,extrapolative or indica...
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A criticalview of univariate calibration techniques developed in the flow injection analysis (FIA) is presented.A classification system based on three main calibration categories-interpolative,extrapolative,extrapolative or indicative-is proposed and rationale behind it discussed.Then,the reasons for rather poor applicability of FIA techniques to routine analysis are considered from various points of view.Finally,a novelapproach to the FIA calibration is suggested:the integrated calibration technique.It is believed to be more acceptablein analyticalpractice due to such features (discussed theoretically and shown experimentally) as reliability,simplicity,versatility and procedural similarity to the common batch calibration technique.
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An original focus on univariate calibration as an experimental process of quantitative analysis is presented. A novel classification system is introduced against the background of the present situation concerning nomenclature of c...
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An original focus on univariate calibration as an experimental process of quantitative analysis is presented. A novel classification system is introduced against the background of the present situation concerning nomenclature of calibration methods. Namely, it has been revealed that four methods well-known in analytical chemistry: the conventional method, the internal standard method, the indirect method and the dilution method, can be split into those carried out in both the interpolative and the extrapolative mode. It is then shown that the basic procedures of all these methods can be modified including different approaches, such as matrix-matched technique, spiking the sample with a reactant, bracketing calibration, and others. For the first time (as compared to monographies dealing with univariate calibration) it is reviewed how the methods are mixed and integrated with one another thereby creating new calibration strategies of extended capabilities in terms of enhanced resistance to the interference and non-linear effects - as the main sources of systematic calibration errors. As additional novelty, rationally possible combinations of the calibration methods - not met hitherto in the literature - have been predicted. Finally, some general rules relating to calibration are formulated and the main calibration problems that still need to be solved are displayed. (C) 2016 Elsevier B.V. All rights reserved.
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摘要 :
The international standard ISO 11843 specifies basic methods to design experiments for estimation of critical values referring to the capability of detection. The detection capability depends on the experimental design, the calibr...
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The international standard ISO 11843 specifies basic methods to design experiments for estimation of critical values referring to the capability of detection. The detection capability depends on the experimental design, the calibration model used, and the errors of the measurement process. This study reports how the specification of the calibration points within the calibration range can be used as a-priori information for evaluation of calibration uncertainty without any consideration of the response variables of the calibration. As result of investigation of the experimental designs, calibration points within the calibration range can be omitted without significant changes of calibration uncertainty. The approach is demonstrated at a practical example, the determination of arsenic in surface water samples taken from a river in Germany.
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Often it is assumed that electronic recording by observers necessarily provides better quality data than pen-and-paper methods. Fifteen novice observers recorded rates of responding from 10 role-played video samples using one of t...
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Often it is assumed that electronic recording by observers necessarily provides better quality data than pen-and-paper methods. Fifteen novice observers recorded rates of responding from 10 role-played video samples using one of three continuous recording input formats:keyboard (laptop), touchscreen (personal digital assistants), or pen-and-paper. We evaluated the quality of the observers' data compared with criterion records using calibration and interobserver agreement algorithms. Results of the calibration analysis revealed that observers in the touchscreen group produced the most consistently accurate and precise data, the keyboard group observers showed wide variation in precision and accuracy, and the pen-and-paper group observers were significantly less precise than the touchscreen group. We conclude that although electronic recording has the potential to be as accurate as, and more precise than, pen-and-paper methods, this is far from guaranteed. Analyses of observers' errors advise recommendations for improving data accuracy and precision when using each method.
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Modelling the hydrology of the Greenland ice sheet, including the filling and drainage of supraglacial lakes, requires melt inputs generated at high spatial and temporal resolution. Here we apply a high spatial (100 m) and tempora...
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Modelling the hydrology of the Greenland ice sheet, including the filling and drainage of supraglacial lakes, requires melt inputs generated at high spatial and temporal resolution. Here we apply a high spatial (100 m) and temporal (1 hour) mass-balance model to a 450 km2 subset of the Paakitsoq region, West Greenland. The model is calibrated by adjusting the values for parameters of fresh snow density, threshold temperature for solid/liquid precipitation and elevation-dependent precipitation gradient to minimize the error between modelled output and surface height and albedo measurements from three Greenland Climate Network stations for the mass-balance years 2000/01 and 2004/05. Bestfit parameter values are consistent between the two years at 400kgm~3, 2°C and +14% (100m)-1, respectively. Model performance is evaluated, first, by comparing modelled snow and ice distribution with that derived from Landsat-7 ETM+ satellite imagery using normalized-difference snow index classification and supervised image thresholding; and second, by comparing modelled albedo with that retrieved from the MODIS sensor MOD10A1 product. Calculation of mass-balance components indicates that 6% of surface meltwater and rainwater refreezes in the snowpack and does not become runoff, such that refreezing accounts for 31% of the net accumulation.
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In recent years, the camera calibration using 1D patterns has been studied and improved by researchers all over the world. However, the progress in that area has been mainly in the sense of reducing the restrictions to the 1D patt...
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In recent years, the camera calibration using 1D patterns has been studied and improved by researchers all over the world. However, the progress in that area has been mainly in the sense of reducing the restrictions to the 1D pattern movement. On the other hand, the method's accuracy still demands improvements. In the present paper, the original technique proposed by Zhang is revisited and we demonstrate that the method's accuracy can be significantly improved, simply by analyzing and reformulating the problem. The numerical conditioning can be improved if a simple data normalization is performed. Furthermore, a non-linear solution based on the Partitioned Levenberg-Marquardt algorithm is proposed. That solution takes advantage of the problem's particular structure to reduce the computational complexity of the original method and to improve the accuracy. Tests using both synthetic and real images demonstrate that the calibration method using 1D patterns can be applied in practice, with accuracy comparable to other already traditional methods.
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Phillip L. Reu discusses about the art and application of 2D digital image correction (DIC) with the help of calibration. The reasons to calibrate in 2D include correcting for lens distortions, obtaining the correct image scaling ...
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Phillip L. Reu discusses about the art and application of 2D digital image correction (DIC) with the help of calibration. The reasons to calibrate in 2D include correcting for lens distortions, obtaining the correct image scaling for units in millimeters, and correcting for non-planar surface. There are some real risks when 2D-calibration is going to be skipped. The primary one is that the measured displacement or strain results may be corrupted by the lens distortions. This is more important when the object is going to be loaded and the loading then results in a translation of the test item across the image, as this will increase the problem. There are a number of things the single camera model cannot tell. Most importantly is the distance from the camera to the object. Because of this, the 2D assumption that the camera remains exactly the same distance from the test object is critically important. If one cannot ensure in-plane motion, or the errors introduced by the motion are too large, he may use stereo-DIC, which removes the in-plane assumptions.
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Computer-based reconstruction models can be used to approximate urban environments. These models are usually based on several mathematical approximations and the usage of different sensors, which implies dependency on many variabl...
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Computer-based reconstruction models can be used to approximate urban environments. These models are usually based on several mathematical approximations and the usage of different sensors, which implies dependency on many variables. The sensitivity analysis presented in this paper is used to weigh the relative importance of each uncertainty contributor into the calibration of a panoramic camera-LiDAR system. Both sensors are used for three-dimensional urban reconstruction. Simulated and experimental tests were conducted. For the simulated tests we analyze and compare the calibration parameters using the Monte Carlo and Latin hypercube sampling techniques. Sensitivity analysis for each variable involved into the calibration was computed by the Sobol method, which is based on the analysis of the variance breakdown, and the Fourier amplitude sensitivity test method, which is based on Fourier's analysis. Sensitivity analysis is an essential tool in simulation modeling and for performing error propagation assessments. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
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