The article discusses the method used in the Central Military Calibration Laboratory to calibrate Fluke 5790 AC/DC transfer standard with reference transfer standard Fluke 792A. It presents the measurement equation and the uncertainty budget. The contribution of uncertainty components in the measurement uncertainty has been presented. The metrological traceability has been evaluated by comparing calibration results with the results in the last Fluke certificate of calibration. Keywords: AC/DC converters, AC/DC difference, thermal voltage converters (TVCs), AC voltage measurement.
Die Kombination von qualitativen Daten mit der Qualitative Comparative Analysis (QCA) verspricht großes analytisches Potenzial, da sie sowohl detaillierte Untersuchungen sozialer Prozesse als auch systematische Fallvergleiche ermöglicht. Viele QCA-Anwendungen greifen auf qualitative Daten zurück. Dennoch bleibt eine zentrale methodologische Frage für QCA-Anwendungen mit qualitativen Daten weitgehend unbeantwortet: Wie können die Informationen qualitativer Daten "kalibriert", das heißt, in formalisierte Fuzzy Sets übersetzt werden? Die sogenannte "Kalibrierung" beeinflusst QCA-Ergebnisse in entscheidender Weise, sodass die Reliabilität des Kalibrierungsverfahrens enormen Einfluss auf die Qualität und Glaubwürdigkeit einer Studie hat. Die fehlende Diskussion der Kalibrierung qualitativer Daten in der methodologischen QCA-Literatur überrascht umso mehr, da QCA in anderen Bereichen stetige methodologische Weiterentwicklungen erfährt und die fehlende Transparenz von Messverfahren in QCA vermehrt kritisiert wird. Im vorliegenden Artikel entwickle ich Anchored Calibration als einen Ansatz zur Kalibrierung qualitativer Daten, der wichtige Lücken in bisherigen Ansätzen schließt und dabei hilft, die Reliabilität von Kalibrierungen zu erhöhen. Anchored Calibration besteht aus drei Arbeitsschritten: 1. der Formulierung eines konzeptuellen Rahmens für Bedingungen und das Outcome, 2. der Verankerung dieses Rahmens in den empirischen Daten und 3. der Anwendung dieses verankerten konzeptuellen Rahmens zur Vergabe von Mitgliedswerten in Fuzzy Sets. Ich diskutiere diese drei Arbeitsschritte sowie die dazu notwendigen Teilschritte im Detail und illustriere das Vorgehen am Beispiel von qualitativen Daten aus Leitfadeninterviews zum Thema Bildungsaufstieg.
"In a repeated game of incomplete information, myopic players form beliefs on next-period play and choose strategies to maximize next-period payoffs. Beliefs are treated as forecast of future plays. Forecast accuracy is assessed using calibration tests, which measure asymptotic accuracy of beliefs against some realizations. Beliefs are calibrated if they pass all calibration tests. For a positive Lebesgue measure of payoff vectors, beliefs are not calibrated. But, if payoff vector and calibration test are drawn from a suitable product measure, beliefs pass the calibration test almost surely"--Federal Reserve Bank of Minneapolis web site
Predicting high pilot mental workload is important to the U.S. Air Force because lives and aircraft can be lost when errors are made during periods of mental overload and task saturation. Current research efforts use psychophysiological measures such as electroencephalography, cardiac, ocular, and respiration measures in an attempt to identify and predict mental workload levels. The primary focus of this effort is the development of a calibration scheme that allows a small subset of salient psychophysiological features developed using actual flight data for one pilot on a given day to accurately classify pilot mental workload for a separate pilot on a different day. To accomplish this objective, the signal-to-noise ratio feature screening method is employed to determine the usefulness of 151 psychophysiological features in feed-forward artificial neural networks. Factor analysis identifies patterns in features that vary with changes in workload level. Methodologies for workload level modification and data calibration are presented and tested. Our results indicate the calibration scheme can increase classification accuracy (CA) over 55%, decrease CA variance by 88%, and decrease by 88% the number of features to process than previous classification methods and classifiers.
National audience ; Air pollution is an increasingly concerning issue in urban areas because of its impact on citizens' health. To tackle pollution effectively, accurate monitoring is a must. Precise stations managed by governmental or specialised institutions do exist, but they are both costly and bulky, which limits the potential to deploy them densely. However, recent progress in micro, connected sensors brings new alternative deployment schemes for dense monitoring by low-cost, imprecise sensors. For such a deployment to be relevant relative to urban air quality monitoring aspects, we are concerned with maintaining the system's properties over time. Indeed, one of the major drawbacks of cheap sensors is their drift: chemical properties degrade over time and alter the measurement accuracy. We challenge this issue by designing distributed, online recalibration procedures. We present a simulation framework modelling a mobile wireless sensor network and we assess the system's measurement confidence using trust propagation paradigms. As WSN calibrations translate as information exchange between sensors, we also study means of limiting the number of such transmissions by skipping the calibrations deemed least profitable to the system. ; La pollution de l'air est un problème majeur en milieu urbain à cause de son impact sur la santé. Afin de lutter efficacement contre cette pollution, il est nécessaire de savoir la mesurer finement. Il existe des stations de mesure gouvernementales ou institutionnelles très précises, cependant elles sont coûteuses et volumineuses, ce qui limite la densité potentielle de leur déploiement. Cependant, les avancées récentes dans le domaine des micro-capteurs connectés soulèvent de nouvelles perspectives de déploiement dense de capteurs bon marché, mais moins précis. Pour en tirer un suivi exploitable de la qualité de l'air, il est nécessaire de conserver les propriétés du système au fil du temps. En effet, l'inconvénient majeur de ces capteurs bon marché est leur dérive : les réactifs ...
National audience ; Air pollution is an increasingly concerning issue in urban areas because of its impact on citizens' health. To tackle pollution effectively, accurate monitoring is a must. Precise stations managed by governmental or specialised institutions do exist, but they are both costly and bulky, which limits the potential to deploy them densely. However, recent progress in micro, connected sensors brings new alternative deployment schemes for dense monitoring by low-cost, imprecise sensors. For such a deployment to be relevant relative to urban air quality monitoring aspects, we are concerned with maintaining the system's properties over time. Indeed, one of the major drawbacks of cheap sensors is their drift: chemical properties degrade over time and alter the measurement accuracy. We challenge this issue by designing distributed, online recalibration procedures. We present a simulation framework modelling a mobile wireless sensor network and we assess the system's measurement confidence using trust propagation paradigms. As WSN calibrations translate as information exchange between sensors, we also study means of limiting the number of such transmissions by skipping the calibrations deemed least profitable to the system. ; La pollution de l'air est un problème majeur en milieu urbain à cause de son impact sur la santé. Afin de lutter efficacement contre cette pollution, il est nécessaire de savoir la mesurer finement. Il existe des stations de mesure gouvernementales ou institutionnelles très précises, cependant elles sont coûteuses et volumineuses, ce qui limite la densité potentielle de leur déploiement. Cependant, les avancées récentes dans le domaine des micro-capteurs connectés soulèvent de nouvelles perspectives de déploiement dense de capteurs bon marché, mais moins précis. Pour en tirer un suivi exploitable de la qualité de l'air, il est nécessaire de conserver les propriétés du système au fil du temps. En effet, l'inconvénient majeur de ces capteurs bon marché est leur dérive : les réactifs ...
International audience ; Nowadays, automotive manufacturers are submitted to strong constraints in engine calibration such as: low fuel consumption, emission-control legislation and driver requests for driving comfort and performances. These constraints lead to an increasing complexity of the engines and thus an increasing number of parameters to be tuned, making the empirical engine calibration by a scan of parameter values impossible at engine test-bench. New methodologies in automated engine calibration based on statistics and optimization have emerged in order to limit the number of experimental tests to be run. The optimization problem of engine calibration consists in the determination of engine tuning parameters that minimize the cumulated fuel consumption and pollutant emissions on a driving cycle generally associated with legislation norms. This cycle is decomposed in a set of stationary operating points of the engine characterized by its speed and its torque (the transient behaviors of the engine are not taken into account in the stabilized calibration). Then, the optimal tuning parameters of the engine should be defined for each operating points, the functions defining these parameters on the whole engine operating domain are called the engine maps. These two-dimensional optimal engine maps are then integrated in the engine control unit in the vehicle. We illustrate the difficulties associated with this application and propose adapted optimization methodologies: LoLiMoT models for engine map parameterization in order to handle intrinsic constraints on the map regularity, multi-objective optimization method based on CMA-ES approach. Finally , application on real dataset obtained at IFP automated test-bench for a diesel engine are presented. 2. Keywords: Engine calibration, LoLiMoT, Multi-objective optimization, Evolutionary algorithm 3. Introduction Engine calibration consists in fulfilling the engine tuning maps that are used in engine controls of the vehicle, i.e. in defining the optimal tuning of parameters used by engine control strategies. Due to the highly increased number of these parameters (especially for diesel engines but spark ignition engines are following the same trend) and the reduction of the development schedule available for the calibration process, manual tuning of engine parameters is now replaced by mathematically assisted calibration process. Such a process is based on the design of experiments with associated modeling methods, in order to reduce the number of tests used to build engine response models depending on engine control parameters, and optimization techniques to determine the optimal settings within the model definition domain. In order to perform the tests in a more productive way, these mathematical techniques are generally associated with test automation, requiring well controlled measurement methods and reliable test equipments. This paper describes the optimization methods developed for this application and illustrates their effectiveness on a real case of a common rail diesel Engine. The first section introduces the classical steps of the calibration process and discusses the associated difficulties. In the second section, we propose the Multi-Objective Covariance-Adaptation Evolutionary Strategy method for solving the optimization problem associated with a given engine operating point defined by the engine speed and the engine load. In the third part, an integrated approach is proposed in order to directly optimize the engine maps on the whole driving cycle (associated with legislation norms) instead of the individual optimization of each engine operating point. 4. Engine calibration 4.1. Sketch of the engine calibration process The emission calibration workflow is classically divided into four steps: 1. a preliminary phase consisting in choosing a sample of operating points (referred to as OP in the 1
International audience ; Nowadays, automotive manufacturers are submitted to strong constraints in engine calibration such as: low fuel consumption, emission-control legislation and driver requests for driving comfort and performances. These constraints lead to an increasing complexity of the engines and thus an increasing number of parameters to be tuned, making the empirical engine calibration by a scan of parameter values impossible at engine test-bench. New methodologies in automated engine calibration based on statistics and optimization have emerged in order to limit the number of experimental tests to be run. The optimization problem of engine calibration consists in the determination of engine tuning parameters that minimize the cumulated fuel consumption and pollutant emissions on a driving cycle generally associated with legislation norms. This cycle is decomposed in a set of stationary operating points of the engine characterized by its speed and its torque (the transient behaviors of the engine are not taken into account in the stabilized calibration). Then, the optimal tuning parameters of the engine should be defined for each operating points, the functions defining these parameters on the whole engine operating domain are called the engine maps. These two-dimensional optimal engine maps are then integrated in the engine control unit in the vehicle. We illustrate the difficulties associated with this application and propose adapted optimization methodologies: LoLiMoT models for engine map parameterization in order to handle intrinsic constraints on the map regularity, multi-objective optimization method based on CMA-ES approach. Finally , application on real dataset obtained at IFP automated test-bench for a diesel engine are presented. 2. Keywords: Engine calibration, LoLiMoT, Multi-objective optimization, Evolutionary algorithm 3. Introduction Engine calibration consists in fulfilling the engine tuning maps that are used in engine controls of the vehicle, i.e. in defining the optimal tuning of ...
This paper was published in OPTICS EXPRESS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OE.19.010769. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law ; Different methods based on photogrammetry or self-calibration exist to calibrate intrinsic and extrinsic camera parameters and also for data pre- and post-processing. From a practical viewpoint, it is quite difficult to decide which calibration method gives accurate results and even whether any data processing is necessary. This paper proposes a set of optimal conditions to resolve the calibration process accurately. The calibration method uses several images of a 2D pattern. Optimal conditions define the number of points and the number of images to resolve the calibration accurately, as well as positions and orientations from where images should be taken. ; This work was partially funded by the Universidad Politecnica de Valencia research funds (PAID 2010-2431 and PAID 10017), Generalitat Valenciana (GV/2011/057) and by Spanish government and the European Community under the project DPI2010-20814-C02-02 (FEDER-CICYT) and DPI2010-20286 (CICYT). ; Ricolfe Viala, C.; Sánchez Salmerón, AJ. (2011). Camera calibration under optimal conditions. Optics Express. 19(11):10770-10776. https://doi.org/10.1364/OE.19.010769 ; S ; 10770 ; 10776 ; 19 ; 11 ; Lin, P. D., & Sung, C. K. (2007). Comparing two new camera calibration methods with traditional pinhole calibrations. Optics Express, 15(6), 3012. doi:10.1364/oe.15.003012 ; Bauer, M., Grießbach, D., Hermerschmidt, A., Krüger, S., Scheele, M., & Schischmanow, A. (2008). Geometrical camera calibration with diffractive optical elements. Optics Express, 16(25), 20241. doi:10.1364/oe.16.020241 ; Choi, K. S., Lam, E. Y., & Wong, K. K. Y. (2006). Automatic source camera identification using the ...
