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A method is developed for determining concentrations in Zeeman electrothermal atomic absorption spectrometry based on the conversion of the transformation function of an atomic absorption spectrometer into a calibration dependence adapted to the matrix of the analyzed sample. The transformation function is expressed as a one-parameter saturation function, which is an integral optical characteristic of the spectrometer, independent of the composition of the analyzed sample. The algorithm of the method includes measurement of the analytical signals of an analyzed sample and a same sample with a known additive of the analyte and calculation of the matrix coefficient and the desired concentration of the analyte in the analyzed sample from these signals. The adaptive calibration method is tested for As, Au, Cd, Cu, Mo, Pd, Pb, Mo, Pd, Pb, Ti, V. The relative systematic error in determining the concentration of an element in the range of measuring the absorbance of atomic vapor does not exceed 10%. The analytical ranges for the elements exceed three orders of magnitude., Author(s): Yu. M. Sadagov [sup.1] , A. Yu. Sadagov [sup.1] Author Affiliations: (1) Cortec Ltd., , 119602, Moscow, Russia The calibration of an analytical instrument is considered a key procedure [...]

doi: 10.1287/trsc.1100.0367 We present an operational framework for the calibration of demand models for dynamic traffic simulations, where calibration refers to the estimation of a structurally predefined model's parameters from [...]

We provide yet another proof of the existence of calibrated forecasters; it has two merits. First, it is valid for an arbitrary finite number of outcomes. Second, it is short [...]

Vicarious calibration (VC) technology, developed in the mid-1980s, has been employed to establish the absolute radiometric calibration of Earth-viewing sensors aboard satellites and aircraft. This method has heretofore required special visits by a field team to collect surface and atmospheric measurements, at specific times necessarily coincident with a sensor overflight. With the recent creation of an autonomous calibration facility, VC data can now be made available to the sensor community without the need for each research group to deploy its own field team. Beginning in mid-November 2006, there have been ongoing efforts to expand the data processing capabilities of the Jet Propulsion Laboratory-operated LED Spectrometer (LSpec) automatic facility, which has been making continual measurements of surface reflectances and atmospheric transmittances since that time. The facility is located at Frenchman Flat, within the Nevada Test Site. Data are used to support the VC of sensors which make observations at visible and near-infrared wavelengths. An array of eight LSpecs performs the autonomous function of recording surface reflectances at 5-min intervals, thereby permitting accurate and continual real-time adjustments to high-resolution Analytical Spectral Devices spectrometer measurements, acquired every several months during on-site visits. Moreover, resident at the LSpec site is a Cimel sunphotometer, used to make atmospheric transmittance measurements. The Cimel is part of the Aerosol Robotic Network (AERONET). Measurements made by the LSpec Cimel are used by AERONET to derive values of aerosol optical depths. From continuous in situ measurement of spectral reflectance of the playa surface, along with acquired aerosol optical depths and ozone optical depths (obtained from the Ozone Mapping Instrument), an LSpec database is being produced and is available via a web-based interface. To highlight the viability of making use of LSpec-derived data, we have executed a few distinct multiple scattering radiative transfer codes in order to perform VCs of the Earth Observing-1 (EO-1) Hyperion and EO-1 Advanced Land Imager sensors. Index Terms--Atmospheric measurements, calibration, remote sensing.

This is the second installment in a series of "LC Troubleshooting" articles on calibration curves for liquid chromatography (LC) separations. Last month's column (1) looked briefly at single-point, two-point, and [...]

This paper presents two new structures for four-port-based systems with ultrawide operating bandwidth, using a combination of power dividers and delay lines. The prototype circuits, initially conceived to operate in the frequency band from I to 4 GHz, are fabricated to validate these new architectures by means of a hybrid integrated-circuit technology. Associated with these systems, a new explicit calibration solution is developed to extend the frequency band of use up to 10 GHz. Comparison between the results obtained from the new structures with those given by a conventional network analyzer show the validity of the systems proposed. Index Terms--Calibration, four-port, quadratic detector, reflectometer, six-port, S-parameters.

This paper addresses the problem of calibrating camera parameters using variational methods. One problem addressed is the severe lens distortion in low-cost cameras. For many computer vision algorithms aiming at reconstructing reliable representations of 3D scenes, the camera distortion effects will lead to inaccurate 3D reconstructions and geometrical measurements if not accounted for. A second problem is the color calibration problem caused by variations in camera responses that result in different color measurements and affects the algorithms that depend on these measurements. We also address the extrinsic camera calibration that estimates relative poses and orientations of multiple cameras in the system and the intrinsic camera calibration that estimates focal lengths and the skew parameters of the cameras. To address these calibration problems, we present multiview stereo techniques based on variational methods that utilize partial and ordinary differential equations. Our approach can also be considered as a coordinated refinement of camera calibration parameters. To reduce computational complexity of such algorithms, we utilize prior knowledge on the calibration object, making a piecewise smooth surface assumption, and evolve the pose, orientation, and scale parameters of such a 3D model object without requiring a 2D feature extraction from camera views. We derive the evolution equations for the distortion coefficients, the color calibration parameters, the extrinsic and intrinsic parameters of the cameras, and present experimental results. Index Terms--Calibration, variational methods, color calibration, lens distortion calibration, camera parameters refinement.

Equity derivative pricing models are calibrated to market data of plain vanilla options by minimization of an error functional. From the economic viewpoint, there are several possibilities to measure the [...]

The in situ procedure for determining the solar calibration constants, originally developed for the PREDE Sun--sky radiometers and based on a modified version of the Langley plot, was applied to a CIMEL instrument located in Valencia, Spain, not integrated into AERONET. Taking into account the different mechanical and electronic characteristics of the two radiometers, the method was adapted to the characteristics of the CIMEL instrument. The iterative procedure for the determination of the solar calibration constants was applied to a 3-year data set. The results were compared with the two sets of experimental calibration constants determined during this period using the standard Langley plot method. The agreement was found to be consistent with the experimental errors, and the method can definitely also be used to determine the solar calibration constant for the CIMEL instrument, improving its calibration. The method can be used provided the radiometer is previously calibrated for diffuse radiance using a standard lamp. a OCIS codes: 010.1290, 010.1110.

This report addresses the task of calibrating an optical sensor for oxygen determination. Detailed analyses of the functional dependences from our measurement system results have been carried out with the additional aim of temperature compensation. As a result, an empirical calibration function has been successfully derived for the luminescent quenching-based oxygen sensor included in a self-designed portable instrument. This function also compensates for the temperature influence on the quenching luminescence process in the range from 0 to 45 [degrees]C. Moreover, the calibration procedure is extremely simple because only a single standard is needed. In fact, the oxygen measurement system can be calibrated with exposure to an open air atmosphere, and therefore, neither laboratory standards nor trained personnel are required. The method has been applied to a set of 11 units of the mentioned sensor (up to 24% oxygen concentration) giving an overall deviation between our calibrated system results and the laboratory standards of 0.3% oxygen concentration (calculated with 95% confidence level). The proposed calibration function has shown itself to be applicable for different sensing film thicknesses and luminophore concentrations using the same fittings parameter. Additionally, this function has been successfully applied to other oxygen dyes. Good agreement has also been found when the performance of the instrument was compared to a commercially available portable instrument based on an electrochemical sensor. We believe that this work could be an interesting finding for spreading the use of optical sensors for atmospheric oxygen determination in commercial measurement equipment for different purposes in confined working atmospheres, such as mines, undergrounds, warehouses, vehicles, and ships.

Near-field beamforming using a microphone array has found many applications, such as sound acquisition in small rooms. However, robust near-field adaptive beamforming (NABF) against focal point errors has not been studied much in the literature until recently. In this brief, a robust near-field adaptive beamformer is proposed. The proposed method is developed by combining a new formulation of the point-constrained NABF and a self-calibration technique, in the presence of focal point uncertainties. The proposed method suffers from no loss in the degrees of freedom for interference rejection. Compared with conventional calibration-based adaptive beamformers, the proposed method has the advantage of not needing a noise-free calibration signal. Simulation results demonstrate that the performance of the proposed method is superior to that of the existing methods. Index Terms--Near-field broadband beamforming, robust adaptive beamforming, microphone arrays.