Journal articles on the topic 'Calibration of solutions'
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Van De Voort, Frederick R., Abdel Aziz Elkashef, and Jean-Simon Blais. "Interlaboratory Assessment of Dry Calibration Milk Powders for Calibrating Infrared Milk Analyzers." Journal of AOAC INTERNATIONAL 74, no. 5 (September 1, 1991): 772–79. http://dx.doi.org/10.1093/jaoac/74.5.772.
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Abstract An interlaboratory study was carried out to assess the performance of preformulated, preanalyzed, dry calibration milk powders designed for calibrating infrared milk analyzers. The calibration powders can be reconstituted to produce consistent calibrations within laboratories. The powders met AOAC specifications In terms of accuracy and repeatability, and provide calibrations with performance characteristics comparable to those produced with conventional calibration milks. The reconstituted solutions were shown to be stable for up to 6 h at 40°C, and can be stored under refrigerated conditions and used for repeated analyses for up to 21 days without apparent deterioration In calibration performance. In general, the calibration powders perform as well as, or better than, the conventional calibrants used by the laboratories participating in the study, and the calibrations could be switched without significantly changing the analytical results. Simulation and cross-calibration analyses indicated that the powdered calibrants produced more consistent results overall than fluid calibration milks. The powdered calibrants, as formulated, are shown to be suitable for any application requiring calibrations that meet AOAC specifications, Including payment applications. The calibration powders have the stability and performance characteristics to serve as a consistent, stable reference standard for monitoring instrument performance, and would be a useful tool for Interlaboratory standardization or accrediting payment and dairy herd analysis laboratories.
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Senn, J. A., J. P. Mills, P. E. Miller, C. Walsh, S. Addy, E. Loerke, and M. V. Peppa. "ON-SITE GEOMETRIC CALIBRATION OF THERMAL AND OPTICAL SENSORS FOR UAS PHOTOGRAMMETRY." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B1-2020 (August 6, 2020): 355–61. http://dx.doi.org/10.5194/isprs-archives-xliii-b1-2020-355-2020.
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Abstract. UAS imagery has become a widely used source of information in geomorphic research. When photogrammetric methods are applied to quantify geomorphic change, camera calibration is essential to ensure accuracy of the image measurements. Insufficient self-calibration based on survey data can induce systematic errors that can cause DEM deformations. The typically low geometric stability of consumer grade sensors necessitates in-situ calibration, as the reliability of a lab based calibration can be affected by transport. In this research a robust on-site workflow is proposed that allows the time-efficient and repeatable calibration of thermal and optical sensors at the same time. A stone building was utilised as calibration object with TLS scans for reference. The approach was applied to calculate eight separate camera calibrations using two sensors (DJI Phantom 4 Pro and Workswell WIRIS pro), two software solutions (Vision Measurement System (VMS) and Agisoft Metashape) and two different subsets of images per sensor. The presented results demonstrate that the approach is suitable to determine camera parameters for pre-calibrating photogrammetric surveys.
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Garbacz, Tomasz, and Ľudmila Dulebova. "Calibration Process and Constructions of Extrusion Calibrators." Key Engineering Materials 635 (December 2014): 135–38. http://dx.doi.org/10.4028/www.scientific.net/kem.635.135.
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In the cellular extrusion process, the extrusion head gives the extrudate the desired cross-section shape and dimensions, taking into account the Barus effect and the shrinkage effect. However, if strict requirements are imposed with regard to cross-section shape and dimensions, it is necessary to fix the shape and dimensions by calibrating the extrudate obtained. The aim of this study is to present methods and constructional solutions of calibration tooling (calibrators) and to present the new calibrator that constitutes a significant element of the adapted and modernized technological extrusion line.
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Sob, U. M., H. L. Bester, O. M. Smirnov, J. S. Kenyon, and C. Russeeawon. "Solution intervals considered harmful: on the optimality of radio interferometric gain solutions." Monthly Notices of the Royal Astronomical Society 504, no. 2 (April 5, 2021): 1714–32. http://dx.doi.org/10.1093/mnras/stab928.
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ABSTRACT Solution intervals are often used to improve the signal-to-noise ratio during radio interferometric gain calibration. This work investigates how factors such as the noise level, intrinsic gain variability, degree of model incompleteness, and the presence of radio frequency interference impact the selection of solution intervals for calibration. We perform different interferometric simulations to demonstrate how these factors, in combination with the choice of solution intervals, affect calibration and imaging outputs and discuss practical guidelines for choosing optimal solution intervals. Furthermore, we present an algorithm capable of automatically selecting suitable solution intervals during calibration. By applying the algorithm to both simulated and real data, we show that it can successfully choose solution intervals that strike a good balance between capturing intrinsic gain variability and not fitting noise as long as the data are not too inhomogeneously flagged. Furthermore, we elaborate on several practical aspects that emphasize the need to develop regularized calibration algorithms that do not require solution intervals.
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Byrne, Ruby, Miguel F. Morales, Bryna J. Hazelton, and Michael Wilensky. "A unified calibration framework for 21 cm cosmology." Monthly Notices of the Royal Astronomical Society 503, no. 2 (March 8, 2021): 2457–77. http://dx.doi.org/10.1093/mnras/stab647.
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ABSTRACT Calibration precision is currently a limiting systematic in 21 cm cosmology experiments. While there are innumerable calibration approaches, most can be categorized as either ‘sky-based,’ relying on an extremely accurate model of astronomical foreground emission, or ‘redundant,’ requiring a precisely regular array with near-identical antenna response patterns. Both of these classes of calibration are inflexible to the realities of interferometric measurement. In practice, errors in the foreground model, antenna position offsets, and beam response inhomogeneities degrade calibration performance and contaminate the cosmological signal. Here, we show that sky-based and redundant calibration can be unified into a highly general and physically motivated calibration framework based on a Bayesian statistical formalism. Our new framework includes sky-based and redundant calibration as special cases but can additionally support relaxing the rigid assumptions implicit in those approaches. We present simulation results demonstrating that, in a simple case, working in an intermediate regime between sky-based and redundant calibration improves calibration performance. Our framework is highly general and encompasses novel calibration approaches including techniques for calibrating compact non-redundant arrays, calibrating to incomplete sky models, and constraining calibration solutions across frequency.
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Salit, Marc L., and Gregory C. Turk. "Traceability of Single-Element Calibration Solutions." Analytical Chemistry 77, no. 7 (April 2005): 136 A—141 A. http://dx.doi.org/10.1021/ac053354n.
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Geladi, Paul, Jim Burger, and Torbjörn Lestander. "Hyperspectral imaging: calibration problems and solutions." Chemometrics and Intelligent Laboratory Systems 72, no. 2 (July 2004): 209–17. http://dx.doi.org/10.1016/j.chemolab.2004.01.023.
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Augustini, Alexander L. R. M., Stefanie Sielemann, and Ursula Telgheder. "Quantitation of Flavor Compounds in Refill Solutions for Electronic Cigarettes Using HS-GCxIMS and Internal Standards." Molecules 27, no. 22 (November 20, 2022): 8067. http://dx.doi.org/10.3390/molecules27228067.
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New regulations on the use of flavor compounds in tobaccoless electronic cigarettes require comprehensive analyses. Gas chromatography coupled ion mobility spectrometry is on the rise as an analytical technique for analyzing volatile organic compounds as it combines sensitivity, selectivity, and easy usage with a full-range screening. A current challenge is the quantitative GCxIMS-analysis. Non-linear calibration methods are predominantly used. This work presents a new calibration method using linearization and its corresponding fit based on the relation between the reactant and analyte ions from the chemical ionization. The analysis of e-liquids is used to compare the presented calibration with an established method based on a non-linear Boltzmann fit. Since e-liquids contain matrix compounds that have been shown to influence the analyte signals, the use of internal standards is introduced to reduce these effects in GCxIMS-analysis directly. Different matrix mixtures were evaluated in the matrix-matched calibration to improve the quantitation further. The system’s detection and quantitation limits were determined using a separate linear calibration. A matrix-matched calibration series of 29 volatile compounds with 12 levels were used to determine the concentration of these substances in a spiked, flavorless e-liquid and a banana-flavored e-liquid, validating the quality of the different calibrations.
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Shishov, Yu A., D. V. Gubanov, M. G. Vahlov, and V. M. Balashov. "Calibration method for large-aperture digital antenna array." Issues of radio electronics, no. 10 (October 31, 2019): 37–44. http://dx.doi.org/10.21778/10.21778/2218-5453-2019-10-37-44.
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Вased on the analysis of known technical solutions, the article proposes a method for calibrating the large-aperture receiving AESA radar for early warning. The peculiarity of this technique is that a coherent radio pulse sequence is applied as the calibration signal supplied to the inputs of the receiving modules. The power of each of the radio pulses is of the same order as the power of the signals arriving at the inputs of the receiving modules when the radar is operating normally, that is, with the signal-to-noise ratio at the input of the AFAR receiving module of 10-6-10-3. Thus, the calibration should occur in the region of small signals, within the working dynamic range. The technical implementation of this technique allows to obtain a higher accuracy of the calibration of the AESA while simplifying the design of the receiving modules, compared with similar technical solutions.
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Телега, Ніна Олександрівна. "Calibration of dataloggers with saturated salt solutions." Ukrainian Metrological Journal, no. 4 (December 29, 2016): 58–60. http://dx.doi.org/10.24027/2306-7039.4.2016.112813.
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Bonnassieux, Etienne, Cyril Tasse, Oleg Smirnov, and Philippe Zarka. "The variance of radio interferometric calibration solutions." Astronomy & Astrophysics 615 (July 2018): A66. http://dx.doi.org/10.1051/0004-6361/201732190.
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This paper investigates the possibility of improving radio interferometric images using an algorithm inspired by an optical method known as “lucky imaging”, which would give more weight to the best-calibrated visibilities used to make a given image. A fundamental relationship between the statistics of interferometric calibration solution residuals and those of the image-plane pixels is derived in this paper. This relationship allows us to understand and describe the statistical properties of the residual image. In this framework, the noise map can be described as the Fourier transform of the covariance between residual visibilities in a new differential Fourier plane. Image-plane artefacts can be seen as one realisation of the pixel covariance distribution, which can be estimated from the antenna gain statistics. Based on this relationship, we propose a means of improving images made with calibrated visibilities using weighting schemes. This improvement would occur after calibration, but before imaging; it is thus ideally used between major iterations of self-calibration loops. Applying the weighting scheme to simulated data improves the noise level in the final image at negligible computational cost.
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Weber, Michael, and Jürg Wüthrich. "CCQM-P32 pilot study. Anion calibration solutions." Metrologia 40, no. 1A (January 2003): 08007. http://dx.doi.org/10.1088/0026-1394/40/1a/08007.
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Dumedah, Gift, Aaron A. Berg, and Mark Wineberg. "Pareto-optimality and a search for robustness: choosing solutions with desired properties in objective space and parameter space." Journal of Hydroinformatics 14, no. 2 (June 22, 2011): 270–85. http://dx.doi.org/10.2166/hydro.2011.120.
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Multi-objective genetic algorithms are increasingly being applied to calibrate hydrological models by generating several competitive solutions usually referred to as a Pareto-optimal set. The Pareto-optimal set comprises non-dominated solutions at the calibration phase but it is usually unknown whether all or only a subset of non-dominated solutions at the calibration phase remains non-dominated at the validation phase. In practice, users would like to know solutions (and their associated properties) which remain non-dominated at both the calibration and validation phases. This study investigates robustness of the Pareto-optimal set by developing a model characterization framework (MCF). The MCF uses cluster analysis to examine the distribution of solutions in parameter space and objective space, and conditional probability to combine linkages between the distributions of solutions in both spaces. The MCF has been illustrated for calibration output generated from application of the Non-dominated Sorting Genetic Algorithm-II to calibrate the Soil and Water Assessment Tool for streamflow in the Fairchild Creek watershed in southern Ontario. Our results show that not all non-dominated solutions found at the calibration phase perform the same for different validation periods. The MCF illustrates that robust solutions – non-dominated solutions which cluster in similar locations in parameter space and objective space – performed consistently well for several validation periods.
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Read, Mark N., Kieran Alden, Louis M. Rose, and Jon Timmis. "Automated multi-objective calibration of biological agent-based simulations." Journal of The Royal Society Interface 13, no. 122 (September 2016): 20160543. http://dx.doi.org/10.1098/rsif.2016.0543.
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Computational agent-based simulation (ABS) is increasingly used to complement laboratory techniques in advancing our understanding of biological systems. Calibration, the identification of parameter values that align simulation with biological behaviours, becomes challenging as increasingly complex biological domains are simulated. Complex domains cannot be characterized by single metrics alone, rendering simulation calibration a fundamentally multi-metric optimization problem that typical calibration techniques cannot handle. Yet calibration is an essential activity in simulation-based science; the baseline calibration forms a control for subsequent experimentation and hence is fundamental in the interpretation of results. Here, we develop and showcase a method, built around multi-objective optimization, for calibrating ABSs against complex target behaviours requiring several metrics (termed objectives ) to characterize. Multi-objective calibration (MOC) delivers those sets of parameter values representing optimal trade-offs in simulation performance against each metric, in the form of a Pareto front. We use MOC to calibrate a well-understood immunological simulation against both established a priori and previously unestablished target behaviours. Furthermore, we show that simulation-borne conclusions are broadly, but not entirely, robust to adopting baseline parameter values from different extremes of the Pareto front, highlighting the importance of MOC's identification of numerous calibration solutions. We devise a method for detecting overfitting in a multi-objective context, not previously possible, used to save computational effort by terminating MOC when no improved solutions will be found. MOC can significantly impact biological simulation, adding rigour to and speeding up an otherwise time-consuming calibration process and highlighting inappropriate biological capture by simulations that cannot be well calibrated. As such, it produces more accurate simulations that generate more informative biological predictions.
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Zelinková, Hana, Rostislav Červenka, and Josef Komárek. "Stabilizing Agents for Calibration in the Determination of Mercury Using Solid Sampling Electrothermal Atomic Absorption Spectrometry." Scientific World Journal 2012 (2012): 1–7. http://dx.doi.org/10.1100/2012/439875.
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Tetramethylene dithiocarbamate (TMDTC), diethyldithiocarbamate (DEDTC), and thiourea were investigated as stabilizing agents for calibration purposes in the determination of mercury using solid sampling electrothermal atomic absorption spectrometry (SS-ETAAS). These agents were used for complexation of mercury in calibration solutions and its thermal stabilization in a solid sampling platform. The calibration solutions had the form of methyl isobutyl ketone (MIBK) extracts or MIBK-methanol solutions with the TMDTC and DEDTC chelates and aqueous solutions with thiourea complexes. The best results were obtained for MIBK-methanol solutions in the presence of2.5 g L-1TMDTC. The surface of graphite platforms for solid sampling was modified with palladium or rhenium by using electrodeposition from a drop of solutions. The Re modifier is preferable due to a higher lifetime of platform coating. A new SS-ETAAS procedure using the direct sampling of solid samples into a platform with an Re modified graphite surface and the calibration against MIBK-methanol solutions in the presence of TMDTC is proposed for the determination of mercury content in solid environmental samples, such as soil and plants.
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Gołąb, Małgorzata, Michał Woźniakiewicz, Paweł M. Nowak, and Paweł Kościelniak. "An Automated Hydrodynamically Mediated Technique for Preparation of Calibration Solutions via Capillary Electrophoresis System as a Promising Alternative to Manual Pipetting." Molecules 26, no. 20 (October 16, 2021): 6268. http://dx.doi.org/10.3390/molecules26206268.
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In this paper, a novel procedure for preparing calibration solutions for capillary electrophoresis (CE)-based quantitative analysis is proposed. Our approach, named the automated hydrodynamically mediated technique (AHMT), uses a capillary and a pressure system to deliver the expected amount of working solution and diluent directly to a sample vial. As a result, calibration solutions are prepared automatically inside the CE instrument, without any or with minimal manual operation. Two different modes were tested: forward and reverse, differing in the direction of hydrodynamic flow. The calibration curves obtained for a model mixture of analytes using AHMT were thorough compared to the standard procedure based on manual pipetting. The results were consistent, though the volume of obtained calibration solutions and the potential risk of random errors were significantly minimized by AHMT. Its effectiveness was further enhanced by the application of SCIEX® nanoVials, reducing the actual volume of calibration solutions down to 10 μL.
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Mosley, Matt, and Ron Williams. "Determination of the Accuracy and Efficiency of Genetic Regression." Applied Spectroscopy 52, no. 9 (September 1998): 1197–202. http://dx.doi.org/10.1366/0003702981945011.
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Genetic regression (GR) is an application of genetic algorithms to the problem of producing optimal calibration models by wavelength selection. GR has been shown to provide excellent calibration models under many conditions that typically result in poor calibration models with the use of other multivariate techniques. In this study, GR is applied to the calibration of the components of a ternary mixture with the use of near-infrared spectroscopic data. To determine how close GR comes to the true global optimum, a random search of the possible solutions was performed and the distribution of the solutions' predictive abilities determined. Through this study it has been determined that GR is capable of searching through extremely large search spaces and eliminating over 99.9999% of the unsuitable solutions in a matter of minutes. GR is also capable of finding multiple solutions of similar quality, something not available in many other calibration techniques. Comparison with results from partial least-squares (PLS) is also included.
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Trabasso, Luis Gonzaga, and Cezary Zielinski. "Semi-automatic calibration procedure for the vision-robot interface applied to scale model decoration." Robotica 10, no. 4 (July 1992): 303–8. http://dx.doi.org/10.1017/s0263574700008134.
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SUMMARYA semi-automatic method for calibrating a robot-vision interface is presented. It puts a small work-load on the operator, requires a simple calibration jig and a solution of a very simple system of equations. It has been extensively used in an experimental robotic cell set up at Loughborough University of Technology, where various aspects of the manufacturing and the decoration of scale models are being investigated. As an extension of the calibration procedure, the paper also shows practical solutions for the problem of dealing with three dimensional objects using a single camera.
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Glick, Mark, and Gary M. Hieftje. "Classification of Alloys with an Artificial Neural Network and Multivariate Calibration of Glow-Discharge Emission Spectra." Applied Spectroscopy 45, no. 10 (December 1991): 1706–16. http://dx.doi.org/10.1366/0003702914335238.
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Artificial neural networks were constructed for the classification of metal alloys based on their elemental constituents. Glow discharge-atomic emission spectra obtained with a photodiode array spectrometer were used in multivariate calibrations for 7 elements in 37 Ni-based alloys (different types) and 15 Fe-based alloys. Subsets of the two major classes formed calibration sets for stepwise multiple linear regression. The remaining samples were used to validate the calibration models. Reference data from the calibration sets were then pooled into a single set to train neural networks with different architectures and different training parameters. After the neural networks learned to discriminate correctly among alloy classes in the training set, their ability to classify samples in the testing set was measured. In general, the neural network approach performed slightly better than the K-nearest neighbor method, but it suffered from a hidden classification mechanism and nonunique solutions. The neural network methodology is discussed and compared with conventional sample-classification techniques, and multivariate calibration of glow discharge spectra is compared with conventional univariate calibration.
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Beser, Katarzyna, Maaijke Mevius, Marcin Grzesiak, and Hanna Rothkaehl. "Detection of Periodic Disturbances in LOFAR Calibration Solutions." Remote Sensing 14, no. 7 (April 2, 2022): 1719. http://dx.doi.org/10.3390/rs14071719.
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The Earth’s ionosphere is a highly variable medium on a wide range of spatio-temporal scales. The responsiveness of plasma to the geomagnetic field and its changes gives rise to anisotropy, which may introduce wave-like characteristics while scanning the ionosphere with a line-of-sight towards a radio source. Previous studies of LOw Frequency ARray (LOFAR) calibration phase solutions report that the estimated beta parameter of a structure function calculated over 6–8 h of astronomical observation timespan has a range of values from 1.6 to 2.0, with an average of 1.89. Such difference between the observations could result from transient wave-like disturbances within the data. This study aims to present a method of signal processing of ionospheric calibration datasets that allows the extraction of a transient wave-like signal and discuss its possible origin. We use complex Morlet wavelet analysis applied to two 8 h observations corresponding to very quiet geomagnetic conditions. We find a wave-like signal in the interferometric Total Electron Content data even during periods of no geomagnetic activity. We suggest it results from the relative velocity changes between the LOFAR line-of-sight and a convection pattern in the ionospheric F layer. Establishing the relationship between quiet time ionosphere, geomagnetic field changes and LOFAR’s calibration solutions may prove beneficial to determination of the dominant signals in the more disturbed conditions, which we leave for future study.
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Sinclair, Andrew J., Ryan E. Sherrill, and T. Alan Lovell. "Calibration of Linearized Solutions for Satellite Relative Motion." Journal of Guidance, Control, and Dynamics 37, no. 4 (July 2014): 1362–67. http://dx.doi.org/10.2514/1.g000037.
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Merl, Reinhard, Christian Jung, Arno Huss, and Kurt Klumaier. "Innovative Solutions for the Calibration of Hybrid Drives." ATZ worldwide 122, no. 5 (April 24, 2020): 38–43. http://dx.doi.org/10.1007/s38311-020-0225-x.
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Croxton, T. L., and W. M. Armstrong. "Calibration of ion-selective microelectrodes." American Journal of Physiology-Cell Physiology 262, no. 5 (May 1, 1992): C1324—C1334. http://dx.doi.org/10.1152/ajpcell.1992.262.5.c1324.
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Measurements of intracellular and extracellular ion activities with ion-selective microelectrodes generally involve calibration of the electrodes in solutions of known composition and fitting of the calibration data with a theoretical expression. The Nicolsky equation is frequently used to describe the variation of electrode potential with primary ion activity in the presence of a constant amount of interference. In this report, we review the estimation of primary ion activities in calibration solutions and discuss the practical use of the Nicolsky equation. We describe a specialized computer program, developed in this laboratory, for routine input and editing of calibration data, fitting of data with the Nicolsky equation, and calculation of experimental ion activities from the fitted curve. Earlier versions of this program have proven helpful in several investigations in this and in other laboratories.
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Mevius, M., F. Mertens, L. V. E. Koopmans, A. R. Offringa, S. Yatawatta, M. A. Brentjens, E. Chapman, et al. "A numerical study of 21-cm signal suppression and noise increase in direction-dependent calibration of LOFAR data." Monthly Notices of the Royal Astronomical Society 509, no. 3 (November 10, 2021): 3693–702. http://dx.doi.org/10.1093/mnras/stab3233.
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ABSTRACT We investigate systematic effects in direction-dependent gain calibration in the context of the Low-Frequency Array (LOFAR) 21-cm Epoch of Reionization (EoR) experiment. The LOFAR EoR Key Science Project aims to detect the 21-cm signal of neutral hydrogen on interferometric baselines of 50–250 λ. We show that suppression of faint signals can effectively be avoided by calibrating these short baselines using only the longer baselines. However, this approach causes an excess variance on the short baselines due to small gain errors induced by overfitting during calibration. We apply a regularized expectation–maximization algorithm with consensus optimization (sagecal-co) to real data with simulated signals to show that overfitting can be largely mitigated by penalising spectrally non-smooth gain solutions during calibration. This reduces the excess power with about a factor of 4 in the simulations. Our results agree with earlier theoretical analysis of this bias-variance trade off and support the gain-calibration approach to the LOFAR 21-cm signal data.
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Zhao, Zijian, and Ying Weng. "A flexible method combining camera calibration and hand–eye calibration." Robotica 31, no. 5 (February 1, 2013): 747–56. http://dx.doi.org/10.1017/s0263574713000040.
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SUMMARYWe consider the conventional techniques of vision robot system calibration where camera parameters and robot hand–eye parameters are computed separately, i.e., first performing camera calibration and then carrying out hand–eye calibration based on the calibrated parameters of cameras. In this paper we propose a joint algorithm that combines the camera calibration and the hand–eye calibration together. The proposed algorithm gives the solutions of the cameras' parameters and the hand–eye parameters simultaneously by using nonlinear optimization. Both simulations and real experiments show the superiority of our algorithm. We also apply our algorithm in the real application of the robot-assisted surgical system, and very good results have been obtained.
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Iwema, Joost, Rafael Rosolem, Mostaquimur Rahman, Eleanor Blyth, and Thorsten Wagener. "Land surface model performance using cosmic-ray and point-scale soil moisture measurements for calibration." Hydrology and Earth System Sciences 21, no. 6 (June 9, 2017): 2843–61. http://dx.doi.org/10.5194/hess-21-2843-2017.
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Abstract. At very high resolution scale (i.e. grid cells of 1 km2), land surface model parameters can be calibrated with eddy-covariance flux data and point-scale soil moisture data. However, measurement scales of eddy-covariance and point-scale data differ substantially. In our study, we investigated the impact of reducing the scale mismatch between surface energy flux and soil moisture observations by replacing point-scale soil moisture data with observations derived from Cosmic-Ray Neutron Sensors (CRNSs) made at larger spatial scales. Five soil and evapotranspiration parameters of the Joint UK Land Environment Simulator (JULES) were calibrated against point-scale and Cosmic-Ray Neutron Sensor soil moisture data separately. We calibrated the model for 12 sites in the USA representing a range of climatic, soil, and vegetation conditions. The improvement in latent heat flux estimation for the two calibration solutions was assessed by comparison to eddy-covariance flux data and to JULES simulations with default parameter values. Calibrations against the two soil moisture products alone did show an advantage for the cosmic-ray technique. However, further analyses of two-objective calibrations with soil moisture and latent heat flux showed no substantial differences between both calibration strategies. This was mainly caused by the limited effect of calibrating soil parameters on soil moisture dynamics and surface energy fluxes. Other factors that played a role were limited spatial variability in surface fluxes implied by soil moisture spatio-temporal stability, and data quality issues.
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Lan, Tian, Kairong Lin, Chong-Yu Xu, Xuezhi Tan, and Xiaohong Chen. "Dynamics of hydrological-model parameters: mechanisms, problems and solutions." Hydrology and Earth System Sciences 24, no. 3 (March 23, 2020): 1347–66. http://dx.doi.org/10.5194/hess-24-1347-2020.
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Abstract. It has been demonstrated that the application of time-varying hydrological-model parameters based on dynamic catchment behavior significantly improves the accuracy and robustness of conventional models. However, the fundamental problems for calibrating dynamic parameters still need to be addressed. In this study, five calibration schemes for dynamic parameters in hydrological models were designed to investigate the underlying causes of poor model performance. The five schemes were assessed with respect to the model performance in different flow phases, the transferability of the dynamic parameters to different time periods, the state variables and fluxes time series, and the response of the dynamic parameter set to the dynamic catchment characteristics. Furthermore, the potential reasons for the poor response of the dynamic parameter set to the catchment dynamics were investigated. The results showed that the underlying causes of poor model performance included time-invariant parameters, “compensation” among parameters, high dimensionality and abrupt shifts in the parameters. The recommended calibration scheme exhibited good performance and overcame these problems by characterizing the dynamic behavior of the catchments. The main reason for the poor response of the dynamic parameter set to the catchment dynamics may be the poor convergence performance of the parameters. In addition, the assessment results of the state variables and fluxes and the convergence performance of the parameters provided robust indications of the dominant response modes of the hydrological models in different sub-periods or catchments with distinguishing catchment characteristics.
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Edler, H. W., F. de Gasperin, and D. Rafferty. "Investigating ionospheric calibration for LOFAR 2.0 with simulated observations." Astronomy & Astrophysics 652 (August 2021): A37. http://dx.doi.org/10.1051/0004-6361/202140465.
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Context. There are a number of hardware upgrades for the Low-Frequency Array (LOFAR) currently under development. These upgrades are collectively referred to as the LOFAR 2.0 upgrade. The first stage of LOFAR 2.0 will introduce a distributed clock signal and allow for simultaneous observations using all the low-band and high-band antennas of the array. Aims. Our aim is to provide a tool for obtaining accurate simulations for LOFAR 2.0. Methods. We present our software for simulating LOFAR and LOFAR 2.0 observations, which includes realistic models for all important systematic effects such as the first- and second-order ionospheric corruptions, time-variable primary-beam attenuation, station-based delays, and bandpass response. The ionosphere is represented as a thin layer of frozen turbulence. Furthermore, thermal noise can be added to the simulation at the expected level. We simulate a full eight-hour simultaneous low- and high-band antenna observation of a calibrator source and a target field with the LOFAR 2.0 instrument. The simulated data are calibrated using readjusted LOFAR calibration strategies. We examine novel approaches of solution-transfer and joint calibration to improve direction-dependent ionospheric calibration for LOFAR. Results. We find that the calibration of the simulated data behaves very similarly to a real observation and reproduces certain characteristic properties of LOFAR data, such as realistic solutions and image quality. We analyze strategies for direction-dependent calibration of LOFAR 2.0 and find that the ionospheric parameters can be determined most accurately when combining the information of the high-band and low-band in a joint calibration approach. In contrast, the transfer of total electron content solutions from the high-band to the low-band shows good convergence but is highly susceptible to the presence of non-ionospheric phase errors in the data.
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Chen, Hsuan-Yu, and Chiachung Chen. "Determination of Optimal Measurement Points for Calibration Equations—Examples by RH Sensors." Sensors 19, no. 5 (March 9, 2019): 1213. http://dx.doi.org/10.3390/s19051213.
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The calibration points for sensors must be selected carefully. This study uses accuracy and precision as the criteria to evaluate the required numbers of calibration points required. Two types of electric relative humidity (RH) sensors were used to illustrate the method and the standard RH environments were maintained using different saturated salt solutions. The best calibration equation is determined according to the t-value for the highest-order parameter and using the residual plots. Then, the estimated standard errors for the regression equation are used to determine the accuracy of the sensors. The combined uncertainties from the calibration equations for different calibration points for the different saturated salt solutions were then used to evaluate the precision of the sensors. The accuracy of the calibration equations is 0.8% RH for a resistive humidity sensor using 7 calibration points and 0.7% RH for a capacitance humidity sensor using 5 calibration points. The precision is less than 1.0% RH for a resistive sensor and less than 0.9% RH for a capacitive sensor. The method that this study proposed for the selection of calibration points can be applied to other sensors.
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Yang, Ming, Jia-Lei Chen, Xiu-Feng Shi, and Hui-Jue Niu. "Rapid Determination of Aesculin, Aesculetin and Fraxetin inCortex FraxiniExtract Solutions Based on Ultraviolet Spectroscopy." E-Journal of Chemistry 8, s1 (2011): S225—S236. http://dx.doi.org/10.1155/2011/294298.
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To evaluate the application of ultraviolet spectroscopy for the rapid determination of aesculin, aesculetin and fraxetin inCortex fraxiniextract solutions, ultraviolet spectra ofCortex fraxiniextract solutions from different batches were collected in the spectral range from 200 nm to 400 nm. The relationship between ultraviolet spectra and chemical parameters displayed some non-linear characteristics. Thus, K-OPLS was proposed to establish the calibration models for the determination ofCortex fraxiniextract solutions between the reference data and ultraviolet spectra. The calibration results were achieved for the determination ofCortex fraxiniextract solutions. The coefficients of determination in calibration (R2) for aesculin, aesculetin and fraxetin were 0.989, 0.957 and 0.939, while in prediction (R2) were 0.982, 0.979 and 0.962, respectively. And the root-mean-square error of prediction (RMSEP) for aesculin, aesculet and fraxetin were 11.99, 3.02 and 1.59 μg/mL. The results demonstrated that ultraviolet spectroscopy could be used for the rapid determination of these three components inCortex fraxiniextract solutions.
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Annus, Ivar, Anatoli Vassiljev, Nils Kändler, and Katrin Kaur. "Automatic Calibration Module for an Urban Drainage System Model." Water 13, no. 10 (May 19, 2021): 1419. http://dx.doi.org/10.3390/w13101419.
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The purpose of the study was to present an automated module for the calibration of urban drainage system models. A prepared tool based on the Open Water Analytics toolkit included 12 additional calibration parameters as compared to the existing similar solutions. The module included a gradient optimization method that allowed adjustment of up to five parameters simultaneously, and a trial-and-error method that provided the possibility of testing one or two parameters. The user interface was built in MS Excel to simplify use of the developed tool. The user can select preferable parameters for calibration, choose the optimization method, and determine the limits for the calculated values. The performance and functionality of the automatic calibration module was tested in two scenarios using the drainage model of a 10 ha heavily developed area in Tallinn, Estonia. The calibration results revealed that the maximum deviation between the modelled and measured flow rates was less than 5% for both cases. This is a reasonably good fit for drainage models, which typically encounter numerous uncertainties. Therefore, it was concluded that the module can be successfully used for calibrating hydraulic models created in SWMM5.
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Ma, Xiao, Xiaotian Du, Lei Li, Caroline Ladegard, Xuanhong Cheng, and James C. M. Hwang. "Broadband Electrical Sensing of a Live Biological Cell with In Situ Single-Connection Calibration." Sensors 20, no. 14 (July 9, 2020): 3844. http://dx.doi.org/10.3390/s20143844.
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Single-connection in situ calibration using biocompatible solutions is demonstrated in single-cell sensing from 0.5 to 9 GHz. The sensing is based on quickly trapping and releasing a live cell by dielectrophoresis on a coplanar transmission line with a little protrusion in one of its ground electrodes. The same transmission line is used as the calibration standard when covered by various solutions of known permittivities. The results show that the calibration technique may be precise enough to differentiate cells of different nucleus sizes, despite the measured difference being less than 0.01 dB in the deembedded scattering parameters. With better accuracy and throughput, the calibration technique may allow broadband electrical sensing of live cells in a high-throughput cytometer.
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Deniz, Cengiz, and Mustafa Cakir. "A solution to the hand-eye calibration in the manner of the absolute orientation problem." Industrial Robot: An International Journal 45, no. 1 (January 15, 2018): 64–77. http://dx.doi.org/10.1108/ir-08-2017-0152.
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Purpose This paper aims to introduce a simple hand-eye calibration method that can be easily applied with different objective functions. Design/methodology/approach The hand-eye calibration is solved by using the closed form absolute orientation equations. Instead of processing all samples together, the proposed method goes through all minimal solution sets. Final result is chosen after evaluating the solution set for arbitrary objectives. In this stage, outliers can be excluded optionally if more accuracy is desired. Findings The proposed method is very flexible and gives more accurate and convenient results than the existing solutions. The mathematical error expression defined by the calibration equations may not be valid in practice, where especially systematic distortions are present. It is shown in the simulations that the solution which results the least mathematical error in systems may have incorrect, incompatible results in the presence of practical demands. Research limitations/implications The performance of the calibration performed with the proposed method is compared with the reference methods in the literature. When the back-projection error is benchmarked, which corresponds to the point repeatability, the proposed approach is considered as the most successful method among all others. Due to its robustness, it is decided to make tooling-sensor calibrations by the recommended method, in the robotic non-destructive testing station in Ford-OTOSAN Kocaeli Plant Body Shop Department. Originality/value Arranging the well-known AX = XB calibration equation in quaternion representation as Q_A = Q_x × Q_B × Q_x reveals another common spatial rotation equation. In this way, absolute orientation solution satisfies the hand-eye calibration equations. The proposed solution is not presented in the literature as a standalone hand-eye calibration method, although some researchers drop a hint to the relative formulations.
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Flom, Walter D., Nobumasa Tanaka, Susan K. Kovats, and Lynda M. Finn. "Improved Procedure for Determining Water Activity in a High Range." Journal of AOAC INTERNATIONAL 69, no. 6 (November 1, 1986): 952–56. http://dx.doi.org/10.1093/jaoac/69.6.952.
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Abstract A procedure for accurate determination of water activity (aw) in a high range (aw between 0.920 and 0.970) using a Beckman Hygroline apparatus was devised because the prescribed calibration procedure was inadequate. This new procedure uses NaCl solutions as standards and the aw values for NaCl solutions reported by Robinson as the reference scale. A quadratic calibration curve: Recorder reading = b0 + b1aw + b2aw2 was established for each sensor. A 3-point calibration scheme, taking measurements of 0.9m (molal), 1.6m, and 2.4m NaCl solutions, was used before and after a series of aw measurements of samples to estimate b0 and verify the constancy of shape of the calibration curve. The equation was solved for aw to convert each recorder reading to an aw value on Robinson’s scale. This procedure yielded precision and accuracy levels for a single determination of 0.0009 and 0.0013 aw unit, respectively. Accuracy of 0.0009 aw unit was obtained by averaging 2 determinations on different sensors.
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Josephs, R. D., M. Bedu, A. Daireaux, Xiuqin Li, Xiaomin Li, Z. Guo, Xianjiang Li, et al. "Key Comparison Study - Organic Solvent Calibration Solution - Gravimetric preparation and value assignment of aflatoxin B1 (AfB1) in acetonitrile (ACN)." Metrologia 59, no. 1A (January 1, 2022): 08002. http://dx.doi.org/10.1088/0026-1394/59/1a/08002.
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Main text The CCQM-K154.b comparison was coordinated by the Bureau International des Poids et Mesures (BIPM) and the Chinese National Institute of Metrology (NIM) on behalf of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) for National Measurement Institutes (NMIs) and Designated Institutes (DIs) which provide measurement services in organic analysis under the 'Comité International des Poids et Mesures' Mutual Recognition Arrangement (CIPM MRA) and/or have participated in the BIPM's Mycotoxin Metrology Capacity Building and Knowledge Transfer (MMCBKT) project as part of its "Metrology for Safe Food and Feed in Developing Economies" Capacity Building Programme. Gravimetrically-prepared solutions having an assigned mass fraction of specified organic analytes are routinely used to calibrate measurement processes for the quantification of the same analytes in matrix samples. Appropriate assignments of the property value and associated uncertainty of calibration solutions thus underpin the traceability of routine analysis and are critical for accurate measurements. Evidence of successful participation in relevant international comparisons is needed to document calibration and measurement capability claims (CMCs) made by national metrology institutes and designated institutes. In total, eleven NMIs/DIs participated in the Track C, Model II, Key Comparison CCQM-K154.b [Gravimetric preparation and value assignment of aflatoxin B1 (AfB1) in acetonitrile (ACN)] for emerging areas of global interest and innovation. Participants were requested to gravimetrically prepare calibration solutions and value assign the mass fractions, expressed in mg/kg, of aflatoxin B1 (AfB1) in the acetonitrile (ACN) solution. Study samples, with assigned values and associated uncertainties were prepared by the comparison participants and sent to the coordinating laboratory for comparison. The Key Comparison Reference Values (KCRVs), calculated form values measured by the coordinating laboratory based on calibrations obtained from independent gravimetrically prepared calibrant solutions, agreed with participants reported values, within their stated uncertainties. AfB1 was selected to be representative of polar aflatoxins. Aflatoxins are a class of mycotoxins generally produced by fungi of the genus Aspergillus. It was anticipated to provide a challenge representative for the gravimetrical preparation and value assignment of calibration solutions in the mass fraction range of 2 mg/kg to 50 mg/kg of mycotoxins with broadly similar structural characteristics. Nine participants of the MMCBKT programme were provided with a stock solution having a known AfB1 mass fraction and expanded uncertainty to use to gravimetrically prepare and value assign a calibration solution. Three NMIs/DIs also participated using their own calibration solutions. The use of in-house solutions required an additional capacity to undertake a fit-for-purpose purity assessment. NIM was the only NMI participating using both the MMCBKT based and their own in-house assigned solutions in order to connect the two different groups. It was decided to propose separate KCRVs for each of the two ampoules provided by the participating NMIs/DIs based on the AfB1 mass fraction. This allowed participants to demonstrate the efficacy of their implementation of the approaches used to gravimetrically prepare calibration solutions and to assess the AfB1 mass fraction. The majority of the AfB1 mass fraction KCRVs (wKCRV) for CCQM-K154.b spanned a mass fraction range of 2.02 mg/kg to 31.57 mg/kg. The relative expanded uncertainties U(wKCRV) ranged from 0.69 % to 2.93 %. Inspection of the degree of equivalence plots for the AfB1 mass fraction assignments in CCQM-K154.b indicated that there was an excellent agreement of results. Solely, the AfB1 mass fraction assignments of INRAP did not agree with the KCRVs. It was found that the samples were altered as a result of an acid contamination. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
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Josephs, R. D., M. Bedu, A. Daireaux, Z. Guo, Xianjiang Li, Y. Gao, Xiuqin Li, et al. "Key comparison study - organic solvent calibration solution - gravimetric preparation and value assignment of deoxynivalenol (DON) in acetonitrile (ACN)." Metrologia 60, no. 1A (December 16, 2022): 08002. http://dx.doi.org/10.1088/0026-1394/60/1a/08002.
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Main text The CCQM-K154.c comparison was coordinated by the the Bureau International des Poids et Mesures (BIPM) and the Chinese National Institute of Metrology (NIM) on behalf of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) for National Measurement Institutes (NMIs) and Designated Institutes (DIs) which provide measurement services in organic analysis under the 'Comité International des Poids et Mesures' Mutual Recognition Arrangement (CIPM MRA) and/or have participated in the BIPM's Mycotoxin Metrology Capacity Building and Knowledge Transfer (MMCBKT) project as part of its "Metrology for Safe Food and Feed in Developing Economies" Capacity Building Programme. Gravimetrically-prepared solutions having an assigned mass fraction of specified organic analytes are routinely used to calibrate measurement processes for the quantification of the same analytes in matrix samples. Appropriate assignments of the property value and associated uncertainty of calibration solutions thus underpin the traceability of routine analysis and are critical for accurate measurements. Evidence of successful participation in relevant international comparisons is needed to document calibration and measurement capability claims (CMCs) made by national metrology institutes and designated institutes. In total, nine NMIs/DIs participated in the Track C, Model II, Key Comparison CCQM-K154.c [Gravimetric preparation and value assignment of deoxynivalenol (DON) in acetonitrile (ACN)] for emerging areas of global interest and innovation. Participants were requested to gravimetrically prepare calibration solutions and value assign the mass fractions, expressed in mg/kg, of deoxynivalenol (DON) in the acetonitrile (ACN) solution. Study samples, with assigned values and associated uncertainties were prepared by the comparison participants and sent to the coordinating laboratory for comparison. The Key Comparison Reference Values (KCRVs), calculated from values measured by the coordinating laboratory based on calibrations obtained from independent gravimetrically prepared calibrant solutions, agreed with participants reported values, within their stated uncertainties. DON belongs to the large group of trichothecene mycotoxins. It is produced by certain fungi of the genus Fusarium that predominantly infect wheat, corn, oats, barley, rice, and other grains in the field or during storage. It was anticipated to provide a challenge representative for the gravimetrical preparation and value assignment of calibration solutions in the mass fraction range of 10 mg/kg to 100 mg/kg of mycotoxins with broadly similar structural characteristics. Ten participants of the MMCBKT programme were provided with a stock solution having a known DON mass fraction and expanded uncertainty to use to gravimetrically prepare and value assign a calibration solution. Three NMIs/DIs also participated using their own calibration solutions. The use of in-house solutions required an additional capacity to undertake a fit-for-purpose purity assessment. NIM was the only NMI participating using both the MMCBKT based and their own in-house assigned solutions in order to connect the two different groups. It was decided to propose separate KCRVs for each of the two ampoules provided by the participating NMIs/DIs based on the DON mass fraction. This allowed participants to demonstrate the efficacy of their implementation of the approaches used to gravimetrically prepare calibration solutions and to assess the DON mass fraction. The majority of the DON mass fraction KCRVs (w KCRV ) for CCQM-K154.c spanned a mass fraction range of 9.88 mg/kg to 123.45 mg/kg. The relative expanded uncertainties U(w KCRV ) ranged from 2.8 % to 6.8 %. Inspection of the degree of equivalence plots for the DON mass fraction assignments in CCQM-K154.c indicated that there was an excellent agreement of results. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
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Rienitz, Olaf, Detlef Schiel, Volker Görlitz, Reinhard Jährling, Jochen Vogl, Judith Velina Lara-Manzano, Agnieszka Zon, et al. "Final report on CCQM-K87: Mono-elemental calibration solutions." Metrologia 49, no. 1A (January 1, 2012): 08010. http://dx.doi.org/10.1088/0026-1394/49/1a/08010.
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Sloan, G. C., T. L. Herter, V. Charmandaris, K. Sheth, M. Burgdorf, and J. R. Houck. "SPECTRAL CALIBRATION IN THE MID-INFRARED: CHALLENGES AND SOLUTIONS." Astronomical Journal 149, no. 1 (December 10, 2014): 11. http://dx.doi.org/10.1088/0004-6256/149/1/11.
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Williams, Chad, John Morkeh, Kathryn Dorfschmidt, Crystal Poon, Paul Matlashewski, and Jose Carvalho. "Innovative Rockfall Solutions Based on Calibration and Field Testing." Mining, Metallurgy & Exploration 37, no. 1 (July 25, 2019): 101–16. http://dx.doi.org/10.1007/s42461-019-0092-4.
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Aminot, Alain, and Roger Kérouel. "Stability and preservation of primary calibration solutions of nutrients." Marine Chemistry 52, no. 2 (April 1996): 173–81. http://dx.doi.org/10.1016/0304-4203(95)00085-2.
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Weber, Michael, and Jürg Wüthrich. "Key comparison CCQM-K29: Anion calibration solutions: final report." Metrologia 43, no. 1A (January 2006): 08012. http://dx.doi.org/10.1088/0026-1394/43/1a/08012.
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Morgan, Jamie. "Piketty's Calibration Economics: Inequality and the Dissolution of Solutions?" Globalizations 12, no. 5 (August 7, 2015): 803–23. http://dx.doi.org/10.1080/14747731.2015.1072950.
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Pelletier, Christine C., James L. Lambert, and Mark Borchert. "Determination of Glucose in Human Aqueous Humor Using Raman Spectroscopy and Designed-Solution Calibration." Applied Spectroscopy 59, no. 8 (August 2005): 1024–31. http://dx.doi.org/10.1366/0003702054615133.
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Glucose concentrations of in vitro human aqueous humor (HAH) samples from cataract patients were determined using 785 nm Raman spectra and partial least squares (PLS) calibration. PLS models were created from spectra of prepared calibration solutions rather than aqueous humor samples. Spectra were obtained with an excitation energy (100 mW for 150 s), which was higher than can be applied in vivo, to decrease the models' contribution to prediction uncertainty. The solutions contained experimentally designed levels of glucose, bicarbonate, lactate, urea, and ascorbate. Multiplicative signal correction of spectra helped compensate for the ±20% drift in laser power observed at the sample over six noncontiguous days of data collection. Seventeen HAH samples containing 38–775 mg/dL of glucose exhibited a root-mean-square error (RMSEP) of 22 mg/dL, coefficient of determination ( r2) of 0.989, and bias of 6 mg/dL when predicted from lower energy (30 s) spectra collected contemporaneously with fifty calibration spectra. Similar results were obtained even when spectral data were gathered separately for human aqueous humor samples and calibration samples: 10 HAH samples, calibrated on 25 solutions measured 3.6 weeks earlier, exhibited an RMSEP of 23 mg/dL, r2 of 0.992, and bias of 9 mg/dL. The results demonstrate progress toward the determination of glucose levels in patient-derived aqueous humor using laboratory-derived “artificial aqueous humor” calibration solutions.
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Lidbe, Abhay D., Alexander M. Hainen, and Steven L. Jones. "Comparative study of simulated annealing, tabu search, and the genetic algorithm for calibration of the microsimulation model." SIMULATION 93, no. 1 (January 2017): 21–33. http://dx.doi.org/10.1177/0037549716683028.
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Microsimulation modeling is one of the contemporary techniques that has potential to perform complex transportation studies faster, safer, and in a less expensive manner. However, to get accurate and reliable results, the microsimulation models need to be well calibrated. Microsimulation model consists of various sub-models each having many parameters, most of which are user-adjustable and are attuned for calibrating the model. Manual calibration involves an iterative trial-and-error process of using the intuitive discrete values of each parameter and feasible combinations of multiple parameters each time until the desired results are obtained. With this approach, it is possible to easily get caught in a never-ending circular process of fixing one problem only to generate another. This can make manual calibration a time-consuming process and is suggested only when the number of parameters is small. However, when the calibration parameter subset is large, an automated process is suggested in the literature. Amongst the meta-heuristics used for calibrating microsimulation models, the genetic algorithm (GA) has been widely used and simulated annealing (SA) has been used only once in the past. Thus, the question of which meta-heuristics is more suitable for the problem of calibration of the microsimulation model still remains open. Thus, the objective of this paper is to evaluate and compare the manual and three (the GA, SA, and tabu search (TS)) meta-heuristics for calibration of microsimulation models. This paper therefore addresses the need to examine and identify the suitability of a meta-heuristics for calibrating microsimulation models. The results show that the meta-heuristics approach can be relied upon for calibrating simulation models very effectively, as it offers the benefit of automating the cumbersome calibrating process. All three meta-heuristics (the GA, SA, and TS) have the ability to find better calibrating parameters than the manually calibrated parameters. The number of better solutions, the best solution, and convergence to the best solution by TS is better than those by the GA and SA. Significant time can be saved by automating calibration of microsimulation models using meta-heuristics. The approach presented in this research can be used to help engineers and planners achieve better modeled results, as the calibration of microsimulation models is likely to become more complex in the future.
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Srinara, S., Y. T. Chiu, M. L. Tsai, and K. W. Chiang. "HIGH-DEFINITION POINT CLOUD MAP-BASED 3D LiDAR-IMU CALIBRATION FOR SELF-DRIVING APPLICATIONS." International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B1-2022 (May 30, 2022): 271–77. http://dx.doi.org/10.5194/isprs-archives-xliii-b1-2022-271-2022.
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Abstract. The multi-sensor fusion scheme has become more and more popular these days with its great potential to estimate reliable navigation information for the modern development in automated driving system (ADS) and mobile mapping systems (MMS). Since these systems are combined with numerous navigation sensors, thus their geometric relationship should be precisely known. This study focuses on practical aspects when calibrating LiDAR-IMU mounting parameters (lever-arms and bore-sight angles) in land-based MMS. This calibration model is based on expressing the mounting parameters within the direct georeferencing equation for each epoch time and conditioning a set of INS/GNSS and LiDAR navigation solutions to lie on it. There is no need for a required information about the planar features in the calibration field as part of the unknowns. Such conditions are only benefitable in the residential area where the presence of sufficient planes in form of building is abundant. We present an approach for recovery the mounting parameters by conditioning the high-definition (HD) point cloud map-based LiDAR information and INS/GNSS navigation solutions through the least-squares solutions. The presented results and discussion mainly focus on practical examples with data from land-based MMS. Preliminary results indicate that correct calibration parameters are not only capable to improve the performance of point cloud georeferencing but also dramatically provide reliable performance evaluation of navigation estimation. Moreover, these findings show that the studied method is not only applicable in the featureless environment but also in its practicality to the self-driving applications.
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Yatawatta, Sarod. "Stochastic calibration of radio interferometers." Monthly Notices of the Royal Astronomical Society 493, no. 4 (March 13, 2020): 6071–78. http://dx.doi.org/10.1093/mnras/staa648.
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ABSTRACT With ever-increasing data rates produced by modern radio telescopes like LOFAR and future telescopes like the SKA, many data-processing steps are overwhelmed by the amount of data that needs to be handled using limited compute resources. Calibration is one such operation that dominates the overall data processing computational cost; none the less, it is an essential operation to reach many science goals. Calibration algorithms do exist that scale well with the number of stations of an array and the number of directions being calibrated. However, the remaining bottleneck is the raw data volume, which scales with the number of baselines, and which is proportional to the square of the number of stations. We propose a ‘stochastic’ calibration strategy where we read only in a mini-batch of data for obtaining calibration solutions, as opposed to reading the full batch of data being calibrated. None the less, we obtain solutions that are valid for the full batch of data. Normally, data need to be averaged before calibration is performed to accommodate the data in size-limited compute memory. Stochastic calibration overcomes the need for data averaging before any calibration can be performed, and offers many advantages, including: enabling the mitigation of faint radio frequency interference; better removal of strong celestial sources from the data; and better detection and spatial localization of fast radio transients.
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Cecílio, Roberto Avelino, Helder De Amorim Mendes, and Sidney Sara Zanetti. "Multiple solutions, multi-site, and parameter transfer to calibrate DHSVM hydrological model." Ciência e Natura 43 (February 1, 2021): e7. http://dx.doi.org/10.5902/2179460x42826.
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The application of hydrologic models often needs sets of input parameters related to environmental attributes which are not always available. This leads to the necessity of calibrating the input parameters. However, due to the non-linearity of the hydrologic phenomena, there may be multiple “best” solutions for the calibration. This paper proposes a method for calibrating the DHSVM hydrologic model using the concepts of multiple solutions, multi-site, and parameter transfer among catchments. Eight watersheds were calibrated, resulting in obtaining five sets of “best” parameters (clusters) for each one. Afterward, each watershed was modeled using the parameters of the other catchments in order to verify if the transfer of the calibrated parameters could promote satisfactory modeling of the streamflows. The results show that clusters calibrated for one watershed may be suitable for other catchments. Besdes, the calibrated parameters of the smaller catchments were satisfactory to simulate the streamflow of the bigger catchments. The proposed method can be useful in calibrating and extrapolating the input parameters to regions that do not have information about them.
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Yan, Xun. "Short-Chain Polysaccharide Analysis in Ethanol–Water Solutions." Journal of AOAC INTERNATIONAL 100, no. 4 (July 1, 2017): 1134–36. http://dx.doi.org/10.5740/jaoacint.16-0426.
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Abstract This study demonstrates that short-chain polysaccharides, or oligosaccharides, could be sufficiently separated with hydrophilic interaction LC (HILIC) conditions and quantified by evaporative light-scattering detection (ELSD). The multianalyte calibration approach improved the efficiency of calibrating the nonlinear detector response. The method allowed easy quantification of short-chain carbohydrates. Using the HILIC method, the oligosaccharide solubility and its profile in water/alcohol solutions at room temperature were able to be quantified. The results showed that the polysaccharide solubility in ethanol–water solutions decreased as ethanol content increased. The results also showed oligosaccharides to have minimal solubility in pure ethanol. In a saturated maltodextrin ethanol (80%) solution, oligosaccharide components with a degree of polymerization >12 were practically insoluble and contributed less than 0.2% to the total solute dry weight. The HILIC–ELSD method allows for the identification and quantification of low-MW carbohydrates individually and served as an alternative method to current gel permeation chromatography procedures.
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Rodríguez, Luis Cuadros, Ana M. García Campaña, Fermin Alés Barrero, Carlos Jiménez Linares, and Manuel Román Ceba. "Validation of an Analytical Instrumental Method by Standard Addition Methodology." Journal of AOAC INTERNATIONAL 78, no. 2 (March 1, 1995): 471–76. http://dx.doi.org/10.1093/jaoac/78.2.471.
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Abstract A statistical procedure to validate an analytical methodology by standard addition methodology is described. The data set obtained in 3 calibration experiments with standard solutions, standard additions, and portions of sample is used. The accuracy of the analytical results is checked by comparison of analyte contents in the different calibrations and from the recovery. Mathematical expressions to estimate the statistical parameters are proposed. The statistical protocol has been applied to fluorimetric determination of molybdenum with alizarin S in vegetable tissues.
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Boyarsky, G., C. Hanssen, and L. A. Clyne. "Inadequacy of high K+/nigericin for calibrating BCECF. II. Intracellular pH dependence of the correction." American Journal of Physiology-Cell Physiology 271, no. 4 (October 1, 1996): C1146—C1156. http://dx.doi.org/10.1152/ajpcell.1996.271.4.c1146.
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In the accompanying study [G. Boyarsky, C. Hanssen, and L.A. Clyne. Am. J. Physiol. 271 (Cell Physiol. 40): C1131-C1145, 1996], it was demonstrated that steady-state intracellular pH (pHi) determined using high K+/nigericin calibrations was systematically in error in vascular smooth muscle (VSM) cells by approximately 0.2 pH units. In this paper the possibility is explored that this correction (pHcor) to the nigericin-calibrated pHi (pHnig) might not be a constant but could vary as pHi varies. The range of pHi during exposures to "null solutions" designed to bracket pHi was extended to acidic and alkaline levels relative to the starting pHi in VSM cells. The pHcor necessary to correct pHnig was linearly dependent on pHnig, increasing from near zero at approximately 6.0 to approximately 0.2 at steady-state pHi, to approximately 0.3 at alkaline pHnig. It is shown how to retrieve previously acquired (tabulated) data using the linear relationship between pHcor and pHnig. Also examined were what corrections must be made to high K+/nigericin calibration curves to correct for this pHi-dependent pHcor. The following changes in the calibration parameters were found: the maximal fluorescence ratio increased from 16.75 to 17.28; the minimal fluorescence ratio decreased from 2.15 to 1.57; and the pK of 2',7'-bis (carboxy-ethyl)-5 (6)-carboxyfluorescein decreased from 7.13 to 6.93. Three potential explanations for these changes are discussed: external [K+] in the nigericin solutions could have been too low; internal [K+] changes during the calibration because of the finite buffering power of cells; and other acid-base transport/generation could have been contributing during the nigericin calibrations (i.e., nigericin does not overwhelm to insignificance other processes generating/consuming H+). The nonconstancy of pHcor is shown to have profound implications for measuring changes in pHi.