Ambient air monitoring for organic compounds, acids, and metals at Los Alamos National Laboratory, January 1991

Williams, C H; Eberhart, C.F.

doi:10.2172/6914375

Cited by 1 publication

(3 citation statements)

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“…It is advisable to fix one of these calibration parameters at their nominal values or to perform coordinate transformation of the correlated parameters to obtain new relatively uncorrelated parameters. An alternative solution to this problem can be achieved by uncoupling the correlated or dependent parameters such that each parameter is calibrated against an independent comparative feature (Williams 2008a).…”

Section: Parameter Sensitivitymentioning

confidence: 99%

“…The common practice is to consider that accurate GPM surrogates are obtained when the number of computer experiments is 10 times or more the number of calibration parameters (Williams 2008b).…”

Section: Surrogate Model -η(X T)mentioning

confidence: 99%

“…To train a surrogate model reliably, the rule of (Williams 2008a). Therefore, a total of 50 samples are generated from uncorrelated, uniformly distributed calibration parameters and accordingly the FE model is run 50 times, at each of the sampled parameter sets.…”

Section: Characterization Of Modeling Parametersmentioning

confidence: 99%

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Calibration under uncertainty for finite element models of masonry monuments

Atamturktur¹,

Hemez²,

Unal³

2010

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About the Cover:The figures on the cover illustrate three aspects of the validation of a computational model developed to predict the vibration response of historic masonry monuments. Top right: The National Cathedral, Washington, DC, where vibration response of vaults is experimentally measured to assess the effect of structural damage. The measurements provide acceleration time series used to verify and validate predictions of the numerical simulation. Top left: The computational finite element model is shown to illustrate the mesh discretization of a vault. The model is analyzed to simulate the vibration response. Colors represent different material properties whose uncertainties are propagated through the calculation. Bottom: The measurement of a vibration mode shape of the structure (solid line) is compared to the prediction of the finite element model (dashed line). Crosses illustrate the uncertainty of predictions due to variability of the boundary conditions and material properties. Statistical tests are implemented to quantify the accuracy of the finite element model, given measurement variability and prediction uncertainty. Tables Table 3- Calibration Under Uncertainty for Finite List of Figures List of ABSTRACTHistorical unreinforced masonry buildings often include features such as load bearing unreinforced masonry vaults and their supporting framework of piers, fill, buttresses, and walls. The masonry vaults of such buildings are among the most vulnerable structural components and certainly among the most challenging to analyze. The versatility of finite element (FE) analyses in incorporating various constitutive laws, as well as practically all geometric configurations, has resulted in the widespread use of the FE method for the analysis of complex unreinforced masonry structures over the last three decades. However, an FE model is only as accurate as its input parameters, and there are two fundamental challenges while defining FE model input parameters: (1) material properties and (2) support conditions. The difficulties in defining these two aspects of the FE model arise from the lack of knowledge in the common engineering understanding of masonry behavior. As a result, engineers are unable to define these FE model input parameters with certainty, and, inevitably, uncertainties are introduced to the FE model.As the complexity of the building increases, as is the case for historical unreinforced masonry buildings, the errors and uncertainties in the analysis also increase. In the presence of high and numerous uncertainties originating from multiple sources, deterministic approaches in which parameters are defined as constant values assumed to be known with certainty cannot be implemented reliably. Probabilistic methods, however, provide a rigorous and rational means in treating the uncertainty present in the FE analysis of historical unreinforced masonry buildings. The way in which uncertainty in historical unreinforced masonry construction is treated is one of the novel and main contributions...

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Section: Parameter Sensitivitymentioning

confidence: 99%

Section: Surrogate Model -η(X T)mentioning

confidence: 99%