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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This can be essential to establishing agreement on any deviations from applicable test code requirements and can help reduce the risk that disagreements regarding the testing method will surface after conducting the test. At other times, a tolerance interval is used when a prediction interval is needed. The effect on the curve-fit is to shift it to the right or left depending on the sign of the errors the signs and magnitudes of the errors are unknown.
ASME PTC 试验不确定度 Test -电源技术相关资料下载-EEWORLD下载中心
The values for h1 and h2 are evaluated at the measured inlet and exit conditions. Its use for such comparisons is than the other two intervals, but that the relative especially appropriate when it is reasonable to sizes uncetainty the tolerance and prediction intervals de- assume that each of the uncertxinty processes has pend upon the proportion of the population to the same statistical variability as measured by the be contained in the prediction interval.
The details of the uncertainty 4 systematic error resulting from imperfect analysis are discussed in paras. Instead of, or in addition to, a confidence interval talk about prediction intervals.
The effect of the propa- gation can be approximated by the Taylor series method see Nonmandatory Appendix C.
ASME PTC 19.1-2005 试验不确定度 Test Uncertainty.pdf
Failure to do so leads to additional errors in the reported test result which are not accounted for in the test uncertainty analysis. From the previous analysis, the conductivity was determined to be k p 3. For the purposes of this example, a summary w of this evaluation is presented in Table Iyer, Colorado State University J. The cator elemental systematic standard uncertainties associ- 6 systematic error resulting from imperfect ated with the error sources identified in para. The time interval must be clearly specified to classify an error, and it may not always be the same interval as the test duration.
The coverage factor is the value from the t distribution for the required confidence level corresponding to the effective degrees of freedom.
The Pitot tube, digital pressure transmitter, and DAS are calibrated together as a system. The value of 2 in the equation is based on the assumption that the population of possible systematic errors is normally distributed.
Journal of Thermophysics and Heat Transfer, 7: This Supplement bXkp an the estimate of the standard deviation kth elemental error source of Note that in eq. Statistical Theory and Methodology in Science and Engineering, 2nd edition.
This interval accounts for systematic errors only. In this case, the calibration random standard uncertainty should be treated as another elemental systematic standard uncertainty and combined with the other calibration systematic standard uncertainties to obtain the total systematic standard uncertainty for the calibration as,e as: When a statistic is calculated from the sample, the degrees tesh freedom associated with the statistic is reduced by one for w every estimated parameter used in calculating the statistic.
Users of a code or standard are expressly advised that determination of ptcc validity of any such patent rights, and the risk of infringement of such rights, is entirely their own responsibility. The second test is then run in the same facility with the design change and hopefully with instruments, setups, and calibrations identical to those used in the first test.
In certain situations, knowledge of the physics asm the measurement system will lead the analyst to believe that the limits of w error are nonsymmetric likely to be larger in either the positive or negative direction. The latter describes the limits to which a systematic error may be expected to go with some confidence. The uncertainty is calculated using the method in subsections through The process is outlined in the following paragraphs.
The results of this uncertainty analysis are presented in Tables and in which each symbol has the same description as in Table w International Organization for Standardization; The best method to minimize the effects of many of these uncertainty sources is to perform overall system calibrations. In a sample of measurements, the degrees of freedom is the sample size N. The calibration process random standard uncertainty is a function of the random standard uncertainties in both the master and test meters.
This could, in turn, lead to expression of an uncertainty interval for a test result that does not encompass the true value. The appa- ratus consists of a closed loop tube containing.
Since only a finite number of measurements are acquired during a test, asje true population mean w and population standard deviation are unknown but can be estimated from sample statistics. 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.
In this case, the user of the thermocouple believes that the true gas temperature falls between the average measured with the thermocouple, X p For example, when comparing asem among various laboratories, it may be appropriate to classify an error as random rather than as systematic even though that error may have been constant for the duration of any single test.
Examples of error sources include Measurement uncertainty can also exist from imperfect calibration tesr, uncontrolled test interactions between a the test instrumentation conditions, measurement methods, environmental and the test media or b between the test article conditions, and data reduction techniques.
A frequent mistake is to calculate a confidence interval on the uncertaingy population ujcertainty when the actual problem calls for a tolerance interval or a prediction interval.
The only differences are the following: The uuncertainty of freedom associated with each Use of the 2 in the above equation is appropriate of the uncertainty estimates are assumed to be as it can be shown using eq. While this point characteristic text be useful for other purposes, it raises a problem in determining performance level. For small degrees of freedom, see Nonmandatory Appendix B.
The second step is to create a bar chart which depicts the percentage contributions of individual systematic and random standard uncertainties to the combined standard uncertainty in descending order of size. The total random population of measurements that is normally dis- error in a measurement is usually the sum of the tributed. 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.
ASME PTC – Test Uncertainty
The end result of an uncertainty analysis is a numerical estimate of the test uncertainty with an appropriate confidence level. A summary of these uncertainties is given in Table Errors of this type should not be included as part of the uncertainty of the measurement.
This is true since the systematic uncertainty component of a parameter BXi is assumed to equal two times the standard deviation square root of the variance of the possible distri- bution of systematic uncertainty. This requires a calculation of the sensitivity factors, either by differentiation or by numerical analysis.