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Calibration Data

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Norbert Ulbrich – 1st expert on this subject based on the ideXlab platform

  • Improved Regression Analysis of Temperature-Dependent Strain-Gage Balance Calibration Data
    31st AIAA Aerodynamic Measurement Technology and Ground Testing Conference, 2015
    Co-Authors: Norbert Ulbrich

    Abstract:

    An improved approach is discussed that may be used to directly include first and second order temperature effects in the load prediction algorithm of a wind tunnel strain-gage balance. The improved approach was designed for the Iterative Method that fits strain-gage outputs as a function of Calibration loads and uses a load iteration scheme during the wind tunnel test to predict loads from measured gage outputs. The improved approach assumes that the strain-gage balance is at a constant uniform temperature when it is calibrated and used. First, the method introduces a new independent variable for the regression analysis of the balance Calibration Data. The new variable is designed as the difference between the uniform temperature of the balance and a global reference temperature. This reference temperature should be the primary Calibration temperature of the balance so that, if needed, a tare load iteration can be performed. Then, two temperature{dependent terms are included in the regression models of the gage outputs. They are the temperature difference itself and the square of the temperature difference. Simulated temperature{dependent Data obtained from Triumph Aerospace’s 2013 Calibration of NASA’s ARC-30K five component semi{span balance is used to illustrate the application of the improved approach.

  • Hidden Connections between Regression Models of Strain-Gage Balance Calibration Data
    51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2013
    Co-Authors: Norbert Ulbrich

    Abstract:

    Hidden connections between regression models of wind tunnel strain–gage balance Calibration Data are investigated. These connections become visible whenever balance Calibration Data is supplied in its design format and both the Iterative and Non–Iterative Method are used to process the Data. First, it is shown how the regression coefficients of the fitted balance loads of a force balance can be approximated by using the corresponding regression coefficients of the fitted strain–gage outputs. Then, Data from the manual Calibration of the Ames MK40 six–component force balance is chosen to illustrate how estimates of the regression coefficients of the fitted balance loads can be obtained from the regression coefficients of the fitted strain–gage outputs. The study illustrates that load predictions obtained by applying the Iterative or the Non–Iterative Method originate from two related regression solutions of the balance Calibration Data as long as balance loads are given in the design format of the balance, gage outputs behave highly linear, strict statistical quality metrics are used to assess regression models of the Data, and regression model term combinations of the fitted loads and gage outputs can be obtained by a simple variable exchange.

  • Detection of Bi-Directionality in Strain-Gage Balance Calibration Data
    28th Aerodynamic Measurement Technology Ground Testing and Flight Testing Conference, 2012
    Co-Authors: Norbert Ulbrich

    Abstract:

    An indicator variable was developed for both visualization and detection of bi-directionality in wind tunnel strain-gage balance Calibration Data. First, the calculation of the indicator variable is explained in detail. Then, a criterion is discussed that may be used to decide which gage outputs of a balance have bi- directional behavior. The result of this analysis could be used, for example, to justify the selection of certain absolute value or other even function terms in the regression model of gage outputs whenever the Iterative Method is chosen for the balance Calibration Data analysis. Calibration Data of NASA s MK40 Task balance is analyzed to illustrate both the calculation of the indicator variable and the application of the proposed criterion. Finally, bi directionality characteristics of typical multi piece, hybrid, single piece, and semispan balances are determined and discussed.

Soroosh Sorooshian – 2nd expert on this subject based on the ideXlab platform

  • automatic Calibration of conceptual rainfall runoff models sensitivity to Calibration Data
    Journal of Hydrology, 1996
    Co-Authors: Patrice Ogou Yapo, Hoshin Vijai Gupta, Soroosh Sorooshian

    Abstract:

    Abstract The identification of hydrologic models requires that appropriate Data be selected for model Calibration. In the research presented here, the shuffled complex evolution (SCE-UA) global optimization method was used to calibrate the NWSRFS-SMA conceptual rainfall-runoff flood forecasting model of the US National Weather Service, using a 40-year record of historical Data. Based on 344 Calibration runs using different lengths of Data from different sections of the historical record, we conclude that approximately 8 years of Data are required to obtain Calibrations that are relatively insensitive to the period selected. Further, the reduction in parameter uncertainty is maximal when the wettest Data periods on record are used. A residual analysis is used to compare the performance of the daily root mean square (DRMS) and heteroscedastic maximum likelihood error (HMLE) objective functions. The results suggest that the factor currently limiting model performance is the unavailability of strategies that explicitly account for model error during Calibration.

D. R. Keyser – 3rd expert on this subject based on the ideXlab platform

  • A Method for the Extrapolation of Calibration Data of PTC 6 Throat Tap Nozzles
    Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 1991
    Co-Authors: J. W. Murdock, D. R. Keyser

    Abstract:

    This paper describes a precise method for extrapolating the coefficient of discharge of PTC 6 throat tap nozzles using all or most of the Calibration Data. Numerical examples are given using actual Calibration Data to describe this method. Because this method permits the use of all Calibration Data at or above Reynolds numbers of 1,000,000 it is a clear improvement over the PTC 6 -1976 method which permits only the highest single point.

  • Theoretical basis for extrapolation of Calibration Data of PTC 6 throat tap nozzles
    Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 1991
    Co-Authors: J. W. Murdock, D. R. Keyser

    Abstract:

    Equations for the extrapolation of Calibration Data for ASME/PTC 6 throat tap nozzles are derived from boundary layer theory. The results match published coefficients with a maximum difference of +0.03 percent