Statistical Approach for Estimating Intervals of Certification or Biases of Facilities or Measurement Systems Including Uncertainties

2005 ◽  
Vol 127 (3) ◽  
pp. 604-610 ◽  
Author(s):  
F. Stern ◽  
A. Olivieri ◽  
J. Shao ◽  
J. Longo ◽  
T. Ratcliffe
Keyword(s):  
Uncertainty Analysis ◽  
Measurement System ◽  
Statistical Approach ◽  
Scale Effects ◽  
Standard Uncertainty ◽  
Cfd Validation ◽  
Towing Tank ◽  
Measurement Systems ◽  
The Mean ◽  
Resistance Tests

A statistical approach for estimating intervals of certification or biases of facilities or measurement systems including uncertainties is set forth based on M×N-order level testing, which is defined as M repetitions of the same N-order level experiment in M different facilities or in the same facility with M different measurement systems. In the absence of reference values, the mean facility or measurement system is used for assessing intervals of certification or biases. Certification or biases of facilities or measurement systems are defined as processes for assessing probabilistic confidence intervals for facilities or measurement systems for specific tests, data reduction equations, conditions, procedures, and uncertainty analysis. Similarly, subgroup analysis is performed for isolating and assessing levels of differences due to use of different model sizes (scale effects) or measurement systems. An example is provided for towing tank facilities for resistance tests using standard uncertainty analysis procedures based on an international collaboration between three facilities. Although the number of facilities are at a minimum, the results demonstrate the usefulness of an approach and support recommendation of future collaborations between more facilities. Knowledge of intervals of certification or biases is important for design, accrediting facilities or measurement systems, and CFD validation.

scholarly journals A statistical approach to quantify uncertainty in carbon monoxide measurements at the Izaña global GAW station: 2008–2011

2012 ◽  
Vol 5 (5) ◽  
pp. 6949-6989 ◽  
Author(s):  
A. J. Gomez-Pelaez ◽  
R. Ramos ◽  
V. Gomez-Trueba ◽  
P. C. Novelli ◽  
R. Campo-Hernandez
Keyword(s):  
Carbon Monoxide ◽  
Response Function ◽  
Measurement System ◽  
Minimum Variance ◽  
Standard Uncertainty ◽  
In Situ Measurements ◽  
North East ◽  
The Mean ◽  
Mean Differences

Abstract. Atmospheric CO in-situ measurements are carried out at the Izaña (Tenerife) global GAW mountain station using a RGA (Reduction Gas Analyser). In-situ measurements at Izaña are representative of the subtropical North-East Atlantic free troposphere, specially during the night period. We present the measurement system configuration, the response function, the calibration scheme, the data processing, the Izaña's 2008–2011 CO nocturnal time series, and the mean diurnal cycle by months. We have developed a rigorous uncertainty analysis for carbon monoxide measurements carried out at the Izaña station which could be applied to other GAW stations. We determine the combined standard uncertainty from four components of the measurement: uncertainty of the WMO standard gases interpolated over the range of measurement, the uncertainty that takes into account the agreement between the standard gases and the response function used, the uncertainty due to the repeatability of the injections, and the propagated uncertainty related to the response function parameters uncertainties (which also takes into account the covariance between the parameters). The mean value of the combined standard uncertainty decreased significantly after March 2009, from 2.37 nmol mol−1 to 1.66 nmol mol−1, due to improvements in the measurement system. A fifth type of uncertainty we call representation uncertainty is considered when some of the data necessary to compute exactly the mean are absent. Any computed mean has also a propagated uncertainty arising from the uncertainties of the data used to compute the mean. The law of propagation depends on the type of uncertainty component (random or systematic). In-situ hourly means are compared with simultaneous and collocated NOAA flask samples. The uncertainty in the differences is determined and whether these are significant. For 2009–2011, only 24.5% of the differences are significant, and 68% of the differences are between −2.39 and 2.5 nmol mol−1. Total and annual mean differences are computed using conventional expressions but also expressions with weights based on the minimum variance method. The annual mean differences for 2009–2011 are well within the ±2 nmol mol−1 compatibility goal of GAW.

Tank Volume Measurement Systems: Volume Measurement Uncertainty Analysis

2004 ◽  
Author(s):  
J. D. Oracheski ◽  
Neil Rausch
Keyword(s):  
United States ◽  
Uncertainty Analysis ◽  
Crude Oil ◽  
Measurement System ◽  
The United States ◽  
Volume Measurement ◽  
Pipeline System ◽  
Measurement Systems ◽  
Volume Measurements ◽  
Products Pipeline

Enbridge Inc. operates the world’s longest crude oil and products pipeline system. The company owns and operates Enbridge Pipelines Inc. (the Canadian portion of the Enbridge crude oil mainline) and a variety of affiliated pipelines in Canada and the United States, including Enbridge Energy Partners, L.P. that operates the Lakehead Pipeline System in the United States. Much of the main pipeline system has been in operation for over 55 years. The mainline system has been in operation for over 55 years. The mainline system is comprised of approximately 15,000 kilometers (9000 miles) of pipeline, 3 million barrels of cavern storage and 3.7 million barrels of tankage (352 tanks) which collectively are integral to transporting more than 2.2 million barrels per day of crude oil and refined products. Enbridge’s measurement needs and practices have continuously evolved, with radar gauging on tanks becoming the standard over the past few years. This paper discusses a number of issues associated with the accuracy of volume measurements in upright, cylindrical petroleum product storage tanks with floating roofs. It includes the analysis and discussion of the process of determining tank volumes and the overall accuracy of a tank volume measurement system. It also includes a discussion of the influence and relevance of each measurement variable on the overall accuracy of tank volume measurements, in order to provide pipeline operators with some insight into determining which variables are most important to the process of tank volume measurement. Finally, it discusses issues regarding tank volume measurement system accuracy, as opposed to overall tank volume measurement accuracy. The focus of this paper is not on the uncertainty analysis process itself, but rather on understanding the results of the uncertainty analysis performed for tank volume measurement systems.

scholarly journals Performance of snow density measurement systems in snow stratigraphies

2021 ◽  
Author(s):  
Hao Jiansheng ◽  
Richard Mind'je ◽  
Feng Ting ◽  
Li Lanhai
Keyword(s):  
Shear Strength ◽  
Measurement System ◽  
Density Measurement ◽  
Field Measurements ◽  
Liquid Water Content ◽  
Snow Density ◽  
Measurement Systems ◽  
Accuracy And Precision ◽  
The Mean ◽  
Precision And Accuracy

Abstract Gravimetric and dielectric permittivity measurement systems (DMS) are applied to measure snow density, but few studies have addressed differences between the two measurement systems under complex snowpack conditions. A field experiment was conducted to measure the snow density using the two measurement systems in stratigraphical layers of different densities, liquid water content (LWC), hardness, and shear strength, and the performance of the two measurement systems was analyzed and compared. The results showed that the snow density from the DMS tended to underestimate by 9% in the dry snowpack and overestimate by 3% in the wet snowpack, expressed as the percentage of the mean density from the gravimetric measurement system (GMS). Compared with the GMS, the DMS has relatively low precision and accuracy in the dry snowpack and similar precision and accuracy in the wet snowpack. The accuracy and precision of the two measurement systems increased with the increase of hardness and shear strength of snow in the dry snowpack, but the accuracy and precision measured of the DMSs increased with the decrease of hardness and shear strength of snow in wet snowpack. The results will help field operators to choose a more reasonable measurement system based on snowpack characteristics to get reliable density data and optimize field measurements.

scholarly journals A statistical approach to quantify uncertainty in carbon monoxide measurements at the Izaña global GAW station: 2008–2011

2013 ◽  
Vol 6 (3) ◽  
pp. 787-799 ◽  
Author(s):  
A. J. Gomez-Pelaez ◽  
R. Ramos ◽  
V. Gomez-Trueba ◽  
P. C. Novelli ◽  
R. Campo-Hernandez
Keyword(s):  
Carbon Monoxide ◽  
Response Function ◽  
Measurement System ◽  
Minimum Variance ◽  
Standard Uncertainty ◽  
In Situ Measurements ◽  
Temporal Consistency ◽  
The Mean ◽  
Mean Differences

Abstract. Atmospheric CO in situ measurements are carried out at the Izaña (Tenerife) global GAW (Global Atmosphere Watch Programme of the World Meteorological Organization – WMO) mountain station using a Reduction Gas Analyser (RGA). In situ measurements at Izaña are representative of the subtropical Northeast Atlantic free troposphere, especially during nighttime. We present the measurement system configuration, the response function, the calibration scheme, the data processing, the Izaña 2008–2011 CO nocturnal time series, and the mean diurnal cycle by months. We have developed a rigorous uncertainty analysis for carbon monoxide measurements carried out at the Izaña station, which could be applied to other GAW stations. We determine the combined standard measurement uncertainty taking into consideration four contributing components: uncertainty of the WMO standard gases interpolated over the range of measurement, the uncertainty that takes into account the agreement between the standard gases and the response function used, the uncertainty due to the repeatability of the injections, and the propagated uncertainty related to the temporal consistency of the response function parameters (which also takes into account the covariance between the parameters). The mean value of the combined standard uncertainty decreased significantly after March 2009, from 2.37 nmol mol−1 to 1.66 nmol mol−1, due to improvements in the measurement system. A fifth type of uncertainty we call representation uncertainty is considered when some of the data necessary to compute the temporal mean are absent. Any computed mean has also a propagated uncertainty arising from the uncertainties of the data used to compute the mean. The law of propagation depends on the type of uncertainty component (random or systematic). In situ hourly means are compared with simultaneous and collocated NOAA flask samples. The uncertainty of the differences is computed and used to determine whether the differences are significant. For 2009–2011, only 24.5% of the differences are significant, and 68% of the differences are between −2.39 and 2.5 nmol mol−1. Total and annual mean differences are computed using conventional expressions but also expressions with weights based on the minimum variance method. The annual mean differences for 2009–2011 are well within the ±2 nmol mol−1 compatibility goal of GAW.

scholarly journals Accuracy of Digitization Using Automated and Manual Methods

1999 ◽  
Vol 79 (6) ◽  
pp. 558-566 ◽  
Author(s):  
Daniel J Wilson ◽  
Bryan K Smith ◽  
J Kyle Gibson ◽  
Byung K Choe ◽  
Brenda C Gaba ◽  
...  
Keyword(s):  
Measurement System ◽  
Angular Speed ◽  
Human Motion ◽  
Motion Measurement ◽  
3 Dimensional ◽  
Measurement Systems ◽  
Mean Error ◽  
Manual Methods ◽  
The Mean ◽  
High Degree

Abstract Background and Purpose. Computerized 3-dimensional (3-D) motion measurement systems are used by those interested in human motion. The purposes of this study were (1) to determine the limits of accuracy in determining intersegmental angles during pendular motion at varying speeds and (2) to determine changes in accuracy introduced by autodigitization and digitization by experienced manual raters. Methods. Angular speed of a T-shaped pendulum was systematically increased by releasing the pendulum from 4 angles (0° [no movement], 45°, 90°, and 120°). Twelve reference angles calculated from markers placed on the pendulum were estimated over 20 frames for 10 trials at each release position. Results. Mean errors across trials and frames for intersegmental angles reconstructed by a 3-D motion measurement system were within ±1 degree across all release positions. An analysis of variance and a post hocTukey test revealed that the mean error for the autodigitized trials was larger than that for the manually digitized trials. For the autodigitized trials, the static trials (release position=0°) produced less mean error than the trials with movement produced. The ICCs showed a high degree of consistency among all raters, ranging from .707 to .999. Conclusion and Discussion. Our findings support the conclusion that under carefully controlled conditions, a 3-D motion measurement system can produce clinically acceptable measurements of accuracy across a range of angular speeds. Furthermore, acceptable accuracy is possible regardless of the digitization method.

Understanding the CoVID-19 pandemic Curve through statistical approach (Preprint)

2020 ◽  
Author(s):  
Ibrar Ul Hassan Akhtar
Keyword(s):  
Probability Density ◽  
Change Point ◽  
Statistical Approach ◽  
Sudden Change ◽  
Global Scale ◽  
Change Point Detection ◽  
Segment Length ◽  
Infected Population ◽  
The Mean ◽  
Point Detection

UNSTRUCTURED Current research is an attempt to understand the CoVID-19 pandemic curve through statistical approach of probability density function with associated skewness and kurtosis measures, change point detection and polynomial fitting to estimate infected population along with 30 days projection. The pandemic curve has been explored for above average affected countries, six regions and global scale during 64 days of 22nd January to 24th March, 2020. The global cases infection as well as recovery rate curves remained in the ranged of 0 ‒ 9.89 and 0 ‒ 8.89%, respectively. The confirmed cases probability density curve is high positive skewed and leptokurtic with mean global infected daily population of 6620. The recovered cases showed bimodal positive skewed curve of leptokurtic type with daily recovery of 1708. The change point detection helped to understand the CoVID-19 curve in term of sudden change in term of mean or mean with variance. This pointed out disease curve is consist of three phases and last segment that varies in term of day lengths. The mean with variance based change detection is better in differentiating phases and associated segment length as compared to mean. Global infected population might rise in the range of 0.750 to 4.680 million by 24th April 2020, depending upon the pandemic curve progress beyond 24th March, 2020. Expected most affected countries will be USA, Italy, China, Spain, Germany, France, Switzerland, Iran and UK with at least infected population of over 0.100 million. Infected population polynomial projection errors remained in the range of -78.8 to 49.0%.

scholarly journals Development of Thermal Performance Metrics for Direct Gas-Fired Circulating Heaters

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 588
Author(s):  
Benjamin C. Smith ◽  
Brett C. Ramirez ◽  
Steven J. Hoff
Keyword(s):  
Mass Flow ◽  
Measurement System ◽  
Thermal Efficiency ◽  
Performance Metrics ◽  
Standardized Test ◽  
Flow System ◽  
Standard Test ◽  
Testing System ◽  
Measurement Systems ◽  
Selection Of

Many climate-controlled agricultural buildings use direct gas-fired circulating heaters (DGFCH) for supplement heat. There is no standardized test to calculate thermal efficiency for these heaters. This study aimed to develop a measurement system and analytical analysis for thermal efficiency, quantify the measurement uncertainty, and assess economics of DGFCH efficiency. The measurement system developed was similar to the ASHRAE 103 standard test stand with adaptations to connect the apparatus to the DGFCH. Two different propane measurement systems were used: input ratings < 30 kW used a mass flow system and input ratings > 30 kW used a volumetric gas meter. Three DGFCHs (21.9, 29.3, 73.3 kW) were tested to evaluate the system. Thermal efficiencies ranged from 92.4% to 100.9%. The resulting uncertainty (coverage factor of 2; ~95% Confidence Interval) ranged from 13.1% to 30.7% for input ratings of 56.3 to 11.4 kW. Key sources of uncertainty were propane and mass flow of air measurement. The economic impact of 1% difference in thermal efficiency ranged from USD $61.3 to $72.0 per heating season. Refinement of the testing system and procedures are needed to reduce the uncertainty. The application of this system will aid building designers in selection of DGFCHs for various applications.

Resistance of a Ship Undergoing Oscillatory Motion

2010 ◽  
Vol 54 (02) ◽  
pp. 120-132
Author(s):  
Lawrence J. Doctors ◽  
Alexander H. Day ◽  
David Clelland
Keyword(s):  
Finite Depth ◽  
Mean Value ◽  
Wave Resistance ◽  
General Effect ◽  
Towing Tank ◽  
Ship Model ◽  
Average Value ◽  
Unsteady Effects ◽  
Oscillatory Cycle ◽  
Resistance Tests

In this paper, we describe extensions to the research of Doctors et al. (Doctors, L. J., Day, A. H., and Clelland, D., 2008, Unsteady effects during resistance tests on a ship model in a towing tank, Journal of Ship Research, 52, 4, 263–273) and Day et al. (Day, A. H., Clelland, D., and Doctors, L. J., 2009, Unsteady finite-depth effects during resistance tests in a towing tank, Journal of Marine Science and Technology, 14, 3, 387–397) in which the oscillations in the wave resistance during the constant-velocity phase of a towing-tank resistance test on a ship model were measured and predicted, in the cases of relatively deep and relatively shallow water. In the current study, the ship model was towed with a harmonic velocity component superimposed on the usual constant forward velocity. This work constitutes a first step in the understanding of the unsteady hydrodynamics of a racing shell (rowing boat). We show here that the unsteady wave resistance varies considerably from the traditional (steady) average value. Indeed, the wave resistance is frequently negative during part of the oscillatory cycle. However, the general effect is an increase in the temporal mean value of the wave resistance; this suggests that every effort should be made to reduce the unsteadiness of the motion. We also demonstrate that the unsteady wave-resistance theory provides an excellent prediction of the measured effects summarized here. These predictions are often within a few percent of the measured values of the resistance.

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