Search results for "Calibration"
showing 10 items of 890 documents
Time calibration of the ANTARES neutrino telescope
2011
The ANTARES deep-sea neutrino telescope comprises a three-dimensional array of photomultipliers to detect the Cherenkov light induced by upgoing relativistic charged particles originating from neutrino interactions in the vicinity of the detector. The large scattering length of light in the deep sea facilitates an angular resolution of a few tenths of a degree for neutrino energies exceeding 10 TeV. In order to achieve this optimal performance, the time calibration procedures should ensure a relative time calibration between the photomultipliers at the level of ~1 ns. The methods developed to attain this level of precision are described.
Optimization of a polarization imaging system for 3D measurements of transparent objects
2009
This paper presents a multispectral imaging system for 3D reconstruction of transparent objects based on "shape from polarization" technique. The originality of this work relies on a multispectral active lighting system which enables to cope with the two ambiguities on the zenith angle and azimuth angle. A calibration step allows optimising the polarimetric measurements. Example of a reconstructed transparent object is presented.
Scene-based spectral calibration assessment of high spectral resolution imaging spectrometers
2009
An accurate knowledge of the spectral calibration of imaging spectrometers is required for optimum data processing and interpretation. The scene-based spectral characterization of imaging spectrometers is frequently necessary to update or replace the pre-flight laboratory-based spectral characterization supplied by the data provider. An automatic method for the estimation of spectral calibration parameters (channel position and bandwidth) at atmospheric absorption regions from high spectral resolution imaging spectrometers (spectral sampling interval below 5 nm) is presented in this contribution. The method has been tested on two commercial instruments with spectral sampling intervals below…
Traffic simulation models calibration using speed–density relationship: An automated procedure based on genetic algorithm
2016
Calibration of traffic models.Calibration as optimization problem.Use of genetic algorithm. This paper presents the first results of a research which applied a genetic algorithm to calibrate a microscopic traffic simulation model based on speed-density relationships. A large set of traffic data collected from the A22 Freeway, Italy, was used and a comparison was performed between the field measurements and the simulation outputs obtained for a test freeway segment by using the Aimsun microscopic simulator.The calibration was formulated as an optimization problem to be solved based on a genetic algorithm; the objective function was defined in order to minimize the differences between the sim…
Assaying multiple 125 I seeds with the well-ionization chamber SourceCheck 4π 33005 and a new insert
2015
PURPOSE To provide a practical solution that can be adopted in clinical routine to fulfill the AAPM-ESTRO recommendations regarding quality assurance of seeds used in prostate permanent brachytherapy. The aim is to design a new insert for the well-ionization chamber SourceCheck(4π) 33005 (PTW, Germany) that allows evaluating the mean air-kerma strength of up to ten (125)I seeds with one single measurement instead of measuring each seed individually. MATERIAL AND METHODS The material required is: a) the SourceCheck(4π) 33005 well-ionization chamber provided with a PTW insert to measure the air-kerma strength S K of one single seed at a time; b) a newly designed insert that accommodates ten s…
Predicting the landslides triggered by the 2009 96E/Ida tropical storms in the Ilopango caldera area (El Salvador, CA): optimizing MARS-based model b…
2019
The main topic of this research was to evaluate the effect in the performance of stochastic landslide susceptibility models, produced by differences between the triggering events of the calibration and validation datasets. In the Caldera Ilopango area (El Salvador), MARS (multivariate adaptive regression splines)-based susceptibility modeling was applied using a set of physical–environmental predictors and two remotely recognized landslide inventories: one dated at 2003 (1503 landslides), which was the result of a normal rainfall season, and one which was produced by the combined effect of the Ida hurricane and the 96E tropical depression in 2009 (2237 landslides). Both the event inventorie…
A high precision calorimeter for hunting the sterile neutrino in the SOX experiment
2019
Abstract A thermal calorimetric apparatus was designed, built and calibrated for measuring the activity of the artificial 144 Ce —144 Pr antineutrino source. This measurement will be performed at the Laboratori Nazionali del Gran Sasso in Italy, just before the source insertion in the tunnel under the Borexino detector and a precision better than 1% is required for a disappearance technique measurement in the SOX (Short distance neutrino Oscillation with BoreXino) project. In this work the apparatus is described and the most important results from the calibration measurements are shown, where the final precision of few per thousand is demonstrated.
Quality of individually calibrated customary printers for assessment of typical dental diagnoses on glossy paper prints: a multicenter pilot study.
2007
Objective The objective of this study was to compare dental radiographs printed on glossy paper from calibrated low-cost printers with monitor display. Study design Three typical intraoral radiographs were selected and a questionnaire was developed with questions assessing accuracy and subjective quality. A test pattern was designed for printer calibration. After calibration, radiographs were printed on glossy paper with 3 ink-jet and 2 thermo-sublimation printers. Sixteen raters evaluated the printed radiographs, 9 of them also on standardized viewing monitors. Subjective ratings were compared, and an ROC-analysis based on expert-consensus monitor readings was performed. Results Low inter-…
Combining Mendonça-Cipolla self-calibration and scene constraints
2011
International audience; In this paper, we propose a method that combines plane parallelism and the Mendonça/Cipolla self-calibration constraints. In our method each pair of images is treated independently and can therefore use a different pair of parallel planes not necessarily visible in the other views. While, for each pair of images, constraints on the singular values of the essential matrix provide two algebraic constraints on the intrinsic parameters, those we derive from plane parallelism have the advantage of providing two additional ones making the calibration of a no-skew camera possible from two images only.
Improved luminosity determination in pp collisions at root s=7 TeV using the ATLAS detector at the LHC
2013
The luminosity calibration for the ATLAS detector at the LHC during pp collisions at sqrt(s) = 7 TeV in 2010 and 2011 is presented. Evaluation of the luminosity scale is performed using several luminosity-sensitive detectors, and comparisons are made of the long-term stability and accuracy of this calibration applied to the pp collisions at sqrt(s) = 7 TeV. A luminosity uncertainty of Delta L/L = +/- 3.5% is obtained for the 47 pb-1 of data delivered to ATLAS in 2010, and an uncertainty of Delta L/L = +/- 1.8% is obtained for the 5.5 fb-1 delivered in 2011.