ASME PTC 19.1 TEST UNCERTAINTY PDF

ASME PTC 19.1 TEST UNCERTAINTY PDF

The edition of ASME PTC will be revised when the Society approves the issuance of the next edition. There will be no Addenda issued to ASME PTC. ASME PTC Test Uncertainty [ASME] on *FREE* shipping on qualifying offers. The scope of this Code is to specify procedures for . (Revision of ASME PTC ). Test Uncertainty. Performance Test Codes. AN AMERICAN NATIONAL STANDARD. Two Park Avenue • New York, NY.

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As elemental sources of standard uncertainty are m not combined as arithmetic sums but are instead combined as described in subsectionderivation of the percentage contribution of an elemental o source of standard uncertainty to the combined uncertainty is computed as etst ratio of the square of the combined standard uncertainty that would.

A weighting principle which is statistically valid 4. The values for t are given in Table B C-3 we will be able to express the mean and variance of r X1, X2.

Steele, Vice Chair G. As can be seen by looking at the formulas shown. In a sample of measurements, the degrees of freedom is the sample size N.

ASME PTC 19.1-2005 试验不确定度 Test Uncertainty.pdf

Ni will be 1 for a single data point or w assigned value of a parameter. As part of this effort the effect of measurement uncertainty must be considered. Let s1 and b1 denote, respectively, the random and systematic standard uncertainties associated with X1. Errors of this type should not be included as part of the uncertainty of the measurement. The results are plotted in Fig. Each additional level in the calibration hierarchy adds uncertainty in the measurement process see Fig.

The fuel consumption of an automotive engine changes with altitude and speed. The compressor inlet and exit total pressures were measured using multiport impact pressure arrays which are permanently installed in the compressor inlet and exit. The approach will be to relate the deviations w in r X1, X2. In some cases, elemental systematic standard uncertainties may arise from the same elemental error source and are therefore correlated.

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Applied Regres- sion Analysis.

The use of back-to-back tests is an excellent method to reduce the systematic standard uncertainty when comparing two or more designs. This is known as a prediction interval. Each bXiXk, term represents the sum of the products of the portions of bXi and bXk that asmme from the same source and are therefore perfectly correlated [10]. Finally, a new time-sharing computer program calculates a wide variety of statistical intervals, including confidence, tolerance, and prediction aasme, Reference 6.

The absolute systematic standard uncertainty, bP, associated with each gage is 3, Pa. For treatment uncertainyy fx nonsymmetric systematic uncertainty see subsec- tion If in each of the N measurements of the variable X the output of an elemental component is averaged Nk times to w obtain Xk, then the method in para.

Note that for this example the derivatives for eq. As noted earlier, the uncertainty expression in eq. For a pump b The rest is operating better than the mini- test, the applied flow might be slightly different mum required design condition. This article also considers additional types of statistical intervals such as: The units of the correlation terms covariancesbXiXk, are the product of the units of Xi and Xk.

The significance of this is discussed in para. Association, 65, December, The value of 2 in the equation is based on the assumption that 119.1 population of possible systematic errors is normally distributed. A normalization coefficient can be estimated from the 119.1 test data in wTable A posttest uncertainty analysis serves to 1 validate the quality of the test result by demonstrating compliance with test requirements; 2 facilitate communication of the quality of the test result to all parties to the test; and 3 facilitate interpretation of the quality of the test by those using the test result.

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This uncertainty of method is sometimes referred to as uncertainty sV 1 0. The tets step is to create a bar chart which depicts the percentage contributions of individual systematic and random standard uncertainties to the tes standard uncertainty in descending order of size.

The cator elemental systematic standard uncertainties associ- 6 systematic error resulting from imperfect ated with the error sources identified in para. John Wiley and Sons; In the first test program, different pressure transducers were used in the tests on the w two designs.

ASME PTC – Test Uncertainty

Depending on the application, vari- w ous confidence levels may be appropriate. However, it the ambient pressure at the test article exhaust and is not always possible to do this. The table has been developed in accordance with the step-bystep procedure of Section 9. Experimentation Uncer- w tainty Analysis for Engineers, 2nd edition.

In general, increasing the number of measurements collected during a test and used in the preceding formulas is beneficial as w a it improves the sample mean as an estimator of the true population mean; b it improves the sample standard deviation as an estimator of the true population standard devia- w tion; and c it typically reduces the value of the random wstandard uncertainty of the sample mean. The true value being measured is the integrated average of the velocity w over the cross-sectional flow area.

The partial derivatives for eq. Thus, an engineer who is concerned with the performance of a mass-produced item, such as a transistor or a lamp, would generally be interested in a tolerance interval to enclose a high proportion of the sampled population.