A multi-step phase calibration procedure for closely spaced multi-tone signals

2010 ◽  
Author(s):  
M. Mirra ◽  
M. Marchetti ◽  
F. Tessitore ◽  
M. Spirito ◽  
L.C.N. de Vreede ◽  
...  
Keyword(s):  
Calibration Procedure ◽  
Phase Calibration

Calibrating a Discrete-Event Simulation for Quantification of Sex-Specific Colorectal Neoplasia Development

2021 ◽  
Author(s):  
Carolina Vivas-Valencia ◽  
Nan Kong ◽  
Aditya Sai ◽  
Thomas F Imperiale
Keyword(s):  
Local Search ◽  
Colorectal Neoplasia ◽  
Discrete Event ◽  
Calibration Procedure ◽  
Disease Models ◽  
Model Parameters ◽  
Two Phase ◽  
Event Simulation ◽  
Male Cohort ◽  
Phase Calibration

Abstract Background: Medical evidence collected from new observational studies can sometimes significantly alter our understanding of disease incidence and progression. This requires efficient and accurate calibration of disease models to help quantify the differences between observed cohorts. However, in model calibration, it is common to encounter overfitting with many model parameters but few observational outcomes. Additionally, the difficulty in evaluating fitting performance is significant due to a large degree of outcome variation and expensive computations for even a single simulation run. Methods: We developed a two-phase calibration procedure to address the above challenges. As a proof-of-the-concept study, we verified the procedure with a discrete-event-simulation-based study on sex-specific colorectal neoplasia development. For the study, we estimated eight disease model parameters that govern colorectal adenoma incidence risk and growth rates at three distinct states: non-advanced, advanced adenoma, and adenoma becoming cancerous. For the calibration, we defined the likelihood measure by a relative weighted sum-of-squares difference between the three actual prevalence values reported in a recent publication and those predicted by a discrete-event colorectal cancer simulation. In phase I of the calibration procedure, we performed a series of low-dimensional sampling-based grid searches to identify reasonably good candidate parameter designs. In phase II, we performed a local search-based approach to further improve the model fit.Results: Overall, our two-phase procedure showed better goodness of fit than a straightforward implementation of the Nelder-Mead algorithm, yielding a 10-fold reduction in calibration error (0.0025 vs. 0.0251 for an all-white mixed-family-history male cohort on the likelihood measure defined above). Further, the two-phase procedure was more effective in calibrating a validated simulation model for a female cohort than a male cohort. Finally, in phase II, performing local search on each of the parameters sequentially is more effective than searching the entire parameter space simultaneously. Conclusions: The proposed two-phase calibration procedure is effective for estimating computationally expensive stochastic dynamic disease models. In addition, initial parameter search range truncation and sensitivity analysis on various parameters can be computationally cost-effective.

Flame ionization detector response to coeluting hydrocarbons and carbon disulphide and its application to the determination of the sum of C6-C11 alkanes and cycloalkanes in air

1983 ◽  
Vol 48 (3) ◽  
pp. 722-734
Author(s):  
Martin Koval
Keyword(s):  
Carbon Disulphide ◽  
Internal Standard ◽  
Calibration Procedure ◽  
Detector Response ◽  
Column Temperature ◽  
Flame Ionization ◽  
Other Substances ◽  
Flame Ionisation Detector ◽  
Ionisation Detector

The flame ionisation detector response to C6-C11 aliphatic hydrocarbon solutions in carbon disulphide in the concentration range between 1.3-9.5 mg ml-1 retained lineary despite the excess of solvent entering the detector simultaneously with the analyte. Pure carbon disulphide exhibited a small positive detector response which did not interfere in calibration procedure and which, under certain GC conditions, inverted to negative values. This response was not proportional to the injected volume and was strongly influenced by the column temperature and/or bleed. On the basis of these findings, a method compatible with the widely used charcoal tube carbon disulphide desorption procedure was developed and evaluated. It consists of static desorption of the sum of aliphatic alkanes and cycloalkanes from the activated charcoal after which an internal standard is added to the supernatant eluate. The resulting carbon disulphide solution is analysed on a highly polar stationary phase 1,2,3-tris(2-cyanoethoxy)propane where the solvent and the analyte coelute in a single peak, the height of which is practically proportional to the sum of alkanes and cycloalkanes present. This also makes determinations of other substances present in the sample more simple. The field test of the proposed method yielded values comparable in precision and accuracy with a control infrared spectrophotometric method.

scholarly journals Mass Spectrometric Calibration Procedure for Real-Time Detection of Lighter Hydrocarbons

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2123
Author(s):  
Makuachukwu F. Mbaegbu ◽  
Puspa L. Adhikari ◽  
Ipsita Gupta ◽  
Mathew Rowe
Keyword(s):  
Real Time ◽  
Mass Spectrometer ◽  
Calibration Procedure ◽  
Mass Spectrometric ◽  
Spectrometric Method ◽  
Mass Selection ◽  
Mass Spectrometric Method ◽  
Mass Spectrometers ◽  
Drilling Rig

Determining gas compositions from live well fluids on a drilling rig is critical for real time formation evaluation. Development and utilization of a reliable mass spectrometric method to accurately characterize these live well fluids are always challenging due to lack of a robust and effectively selective instrument and procedure. The methods currently utilized need better calibration for the characterization of light hydrocarbons (C1–C6) at lower concentrations. The primary goal of this research is to develop and optimize a powerful and reliable analytical method to characterize live well fluid using a quadruple mass spectrometer (MS). The mass spectrometers currently being used in the field have issues with detection, spectra deconvolution, and quantification of analytes at lower concentrations (10–500 ppm), particularly for the lighter (<30 m/z) hydrocarbons. The objectives of the present study are thus to identify the detection issues, develop and optimize a better method, calibrate and QA/QC the MS, and validate the MS method in lab settings. In this study, we used two mass spectrometers to develop a selective and precise method to quantitatively analyze low level lighter analytes (C1–C6 hydrocarbons) with masses <75 m/z at concentrations 10–500 ppm. Our results suggest that proper mass selection like using base peaks with m/z 15, 26, 41, 43, 73, and 87, respectively, for methane, ethane, propane, butane, pentane, and hexane can help detect and accurately quantify hydrocarbons from gas streams. This optimized method in quadrupole mass spectrometer (QMS) will be invaluable for early characterization of the fluid components from a live hydrocarbon well in the field in real time.

Simple Index to Assess the Calibration Quality of Safety Performance Functions Based on Multiple Goodness-of-Fit Metrics

2021 ◽  
pp. 036119812110088
Author(s):  
Raul E. Avelar ◽  
Karen Dixon ◽  
Boniphace Kutela ◽  
Sam Klump ◽  
Beth Wemple ◽  
...  
Keyword(s):  
Goodness Of Fit ◽  
Synthetic Data ◽  
Calibration Procedure ◽  
Safety Performance ◽  
Absolute Deviation ◽  
Data Set ◽  
Safety Database ◽  
Simple Index ◽  
Safety Performance Functions

The calibration of safety performance functions (SPFs) is a mechanism included in the Highway Safety Manual (HSM) to adjust SPFs in the HSM for use in intended jurisdictions. Critically, the quality of the calibration procedure must be assessed before using the calibrated SPFs. Multiple resources to aid practitioners in calibrating SPFs have been developed in the years following the publication of the HSM 1st edition. Similarly, the literature suggests multiple ways to assess the goodness-of-fit (GOF) of a calibrated SPF to a data set from a given jurisdiction. This paper uses the calibration results of multiple intersection SPFs to a large Mississippi safety database to examine the relations between multiple GOF metrics. The goal is to develop a sensible single index that leverages the joint information from multiple GOF metrics to assess overall quality of calibration. A factor analysis applied to the calibration results revealed three underlying factors explaining 76% of the variability in the data. From these results, the authors developed an index and performed a sensitivity analysis. The key metrics were found to be, in descending order: the deviation of the cumulative residual (CURE) plot from the 95% confidence area, the mean absolute deviation, the modified R-squared, and the value of the calibration factor. This paper also presents comparisons between the index and alternative scoring strategies, as well as an effort to verify the results using synthetic data. The developed index is recommended to comprehensively assess the quality of the calibrated intersection SPFs.

scholarly journals A calibration procedure for the assessment of work hardening part I: Effects of the microstructure and load type

2021 ◽  
Vol 175 ◽  
pp. 111067
Author(s):  
J.P. Goulmy ◽  
E. Rouhaud ◽  
P. Kanoute ◽  
L. Toualbi ◽  
S. Kruch ◽  
...  
Keyword(s):  
Work Hardening ◽  
Calibration Procedure
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