The Specialist Committee on Uncertainty Analysis Final Report and - PDF document

Proceedings of 25th ITTC – Volume II 433 The Specialist Committee on Uncertainty Analysis Final Report and Recommendations to the 25th ITTC 1. INTRODUCTION Southern Europe appointed a new member to replace him. 1.1 Membership and Meetings The uncertainty analysis committee (UAC) was appointed by the 24th ITTC in Edinburgh, Scotland, 2005, and it consists of the following members shown in Figure 1: � Dr. Joel T. Park (Chairman): Naval Surface Warfare Center Carderock Division, NSWCCD, West Bethesda, Maryland, USA. � Dr. Ahmed Derradji-Aouat (Secretary): National Research Council Canada, Insti- tute for Ocean Technology, NRC-IOT, Newfoundland and Labrador, Canada. Figure 1 Photograph of Uncertainty Analysis � Mr. Baoshan Wu: China Ship Scientific Committee during its first meeting in France at Research Centre, CSSRC, Wuxi, Jiangsu, BEC. Viewer’s left to right are: Mr. Baoshan China. Wu (China), Dr. Ahmed Derradji-Aouat (Can- � Dr. Shigeru Nishio: Kobe University, Fac- ada), Mr. Erwan Jacquin (France), Dr. Joel Park ulty of Maritime Sciences, Department of (USA), and Dr. Shigeru Nishio (Japan). Maritime Safety Management, Kobe, Japan. � Mr. Erwan Jacquin: Formerly a staff mem- ber of the Bassin d’Essais des Carènes, 1.2 Terms of Reference BEC, Val-de-Reuil, France. From the reference document provided by Four (4) UAC meetings were held. The host the 24 th ITTC via the Advisory Council (AC), Countries, host laboratories, and dates of the the UAC was tasked to develop 5 new proce- meetings were: dures and revise another five (5) existing pro- � France, BEC, March 30-31, 2006. cedures. A total of 10 procedures were to be � China, CSSRC, October 23-25, 2006. completed. � Canada, NRC-IOT, June 7-8, 2007. � USA, NSWCCD, January 30-February 1, The five new uncertainty analysis proce- 2008. dures were for the following topics: Captive model testing � After the meeting in China, Mr. Erwan Jac- Free running model testing � quin left his position at BEC and the UAC. Laser Doppler Velocimetry (LDV) � Neither the BEC nor the ITTC representative of Particle Imaging Velocimetry (PIV) � Full-scale testing �

The Specialist Committee on Uncertainty Analysis 434 the 24 th ITTC in 2005, the ITTC opted for the Since the UAC started with only with 5 members, the departure of Mr. E. Jacquin from method of AIAA (1995), which was revised as the BEC, France, led to the decision to elimi- AIAA (1999) for the development of ITTC UA nate the work for full-scale testing. Addition- procedures. AIAA (1999) is for wind tunnel ally, future full-scale test procedures may be testing. The UA standards for wind tunnel test- derived from the procedures on captive and ing were considered applicable to experimental free-running model tests. hydrodynamics and tow tank testing. The five existing uncertainty analysis pro- Starting in 2005 just after the creation of the UAC during the 24 th ITTC, ITTC member or- cedures that were to be revised are as follows: � 7.5-02-01-01 Uncertainty Analysis in EFD, ganizations from geographic areas other than Uncertainty Assessment Methodology (19 North America have demanded the use of ISO pages) (1995) rather than AIAA (1999) or ASME � 7.5-02-01-02 Uncertainty Analysis in EFD, (2005). Both AIAA and ASME are American Guidelines for Resistance Towing Tank organizations, and ISO was viewed as the le- Tests (5 pages) gitimate international organization for guides � 7.5-02-03-01.2 Propulsion, Performance and standards development. Uncertainty Analysis, Example for Propul- sion Test (26 pages) Since the procedures for development by � 7.5-02-03-02.2 Propulsion, Propulsor Un- the UAC should be consistent with ISO (1995), certainty Analysis, Example for Open Wa- the review of the 3 procedures 7.5-02-03-01.2, ter Test (15 pages) 7.5-2-03-02.2, and 7.5-02-07-03.2 were post- � 7.5-02-07-03.2 Testing and Extrapolation poned after completion of ITTC (2008a). The Methods Loads and Responses, Ocean En- development of the 2 new procedures on LDV gineering Analysis Procedure for Model and PIV were possible because the committee Tests in Regular Waves (8 pages). members were specialists in the subject areas as well as in ISO (1995). ITTC procedure 7.5-02-07-03.2 did not have an uncertainty component; therefore, An uncertainty analysis procedure for free- nothing was available to review. The UAC may running model testing was not developed. In- provide a document to the appropriate commit- stead, the UAC provides an example on the ap- tee so it can be added to that existing procedure. plication of uncertainty analysis to free-running models in section 12 of this report. During the first meeting in France, the UAC concluded that ITTC 7.5-02-01-02 could be As a consequence for adoption of the ISO eliminated since it provided no new informa- (1995) as the basis of ITTC (2008a), all exist- tion in support of ITTC 7.5-02-01-02. The ing and recommended ITTC UA procedures UAC subsequently submitted two revised pro- should be reviewed and revised accordingly. The 26 th ITTC General and Specialist Commit- cedures, ITTC (2008a, b). More importantly, during the first meeting in France, the UAC de- tees should harmonize their existing UA proce- cided to adopt a more inclusive philosophy and dures with ITTC (2008a). Any new UA proce- follow the guidelines of the ISO (1995), also dures should also follow this new procedure as known as ISO-GUM (Guide to the Expression well. The UAC will provide assistance and of Uncertainty in Measurements). guidance to various ITTC committees for har- monization of their existing and new proce- Application of the ISO (1995) to experi- dures. Since ISO (1995) is concerned only with mental hydrodynamics is a fundamental shift in general guidelines for expressing uncertainties thinking and in assessing uncertainties from in measurements, specific disciplines such as what the ITTC historically had followed. Up to experimental hydrodynamics should produce

Proceedings of 25th ITTC – Volume II 435 specific UA procedures and show how the ISO � 7.5-02-01-02. Guidelines for Uncertainty (1995) guidelines are implemented. Analysis in Resistance Towing Tank Tests. � 7.5-01-03-01. Uncertainty Analysis: In- strument Calibrations. 1.3 Additional Activities � 7.5-01-03-02. Uncertainty Analysis: Laser Doppler Velocimetry (LDV). The UAC proposed a new procedure on in- � 7.5-01-03-03. Uncertainty Analysis: Parti- strument calibration, ITTC (2008c). Although cle Imaging Velocimetry (PIV). the ITTC terms of reference did not include a mandate for such a procedure, a procedure for 3. STRUCTURE OF THE REPORT UA Instrument Calibration is a fundamental extension to the general procedure (ITTC, 2008a). This document is divided into four sections: � Uncertainty Analysis section that includes In addition to the AC mandated tasks, the general literature for the UA, its history, UAC played a proactive role in interacting and its importance, and why it is needed. discussing UA related issues with other ITTC � Summary for the new and revised proce- committees. Among these committees are the dure completed by the UAC. Specialist Committee on Powering, Perform- � Other activities section that includes inter- ance Prediction, the Propulsion Committee, the actions with other ITTC committees, dis- Manoeuvring Committee, Resistance Commit- cussion of UA application to free running tee, and the Seakeeping Committee. Some lim- model tests, and UA in fundamental equa- ited discussions with members of the Specialist tions for water properties (density, viscos- Committee on Ice took place. ity and vapour pressure). � Conclusions and recommendations. 1.4 Symbols and Definitions 4. UNCERTAINTY ANALYSIS The basic and general definitions for me- trology terms in ITTC (2008a) are the same as 4.1 Brief History of Uncertainty Analysis those given by the International Vocabulary for Metrology (VIM, 2007). This is also an ISO publication from the Bureau International des Modern uncertainty analysis in North Poids et Mesures (BIPM) that is complimentary America evolved from a series of papers pub- to the ISO (1995). Among these, are definitions lished by professors and their students from for terms such as “measurand”, “measurement”, Stanford University, S. R. Kline, R. J. Moffat, “error”, “uncertainty”, “repeatability”, “repro- and H. W. Coleman. The earliest paper was by ducibility”, and other expressions routinely Kline and McKlintock (1953). They introduced mentioned in ISO (1995). concepts such as single sample uncertainty, un- certainty interval, and the law of propagation of uncertainty. Kline and McKlintock (1953) also 2. COMPLETED PROCEDURES suggested describing the uncertainty with 20 to 1 odds. In current practice, uncertainty esti- Five procedures were completed by the mates are stated at the 95 % confidence level UAC, all based on ISO (1995) guidelines. The rather than 20 to 1 odds, which are equivalent. five procedures are: � 7.5-02-01-01. Guide to the Expression of In the international community, a group of Uncertainty in Experimental Hydrodynam- experts formulated recommendation INC-1 ics. (1980) “expression of uncertainty in measure-