In June 2009, the Laboratory in hydrology of Nancy (Ansès-LHN, Nancy) conducted anexploratory inter-laboratory proficiency tests (ILT) test in collaboration with theAQUAREF network to identify laboratory practices and estimate inter-laboratory uncertaintyfor the compounds under study. There were a total of 12 compounds belonging to sixfamilies (hormones, antibiotics, non-steroidal anti-inflammatory drugs, beta blockers,antipsychotics and others) including one compound used in veterinary medicine. It was thefirst ILT conducted in France on water intended for human consumption. Thirty-onelaboratories participated, 4 of which were located abroad.

Optimum safety and reliability can be achieved by coordinating an interlaboratoryproficiency testing among different laboratories. Testing laboratories need to verifytheir test procedures and testing capability for reliable results. In this study,equivalent samples are prepared by cellulose based transformed board material used intransformers as electrical isolation material. Randomly selected test samples havingspecified dimensions are sent to the participant laboratories. Then they are tested andresults are analyzed according to previously defined parameters. Each laboratory appliedtensile and flexural tests on the samples according to procedures given in IEC 60641-2,2004 and IEC 60763-2, 2007 standards respectively. Test results are evaluated according tosame procedures explained in related standards by the participant laboratories. TUBITAKUME Material Testing Laboratory being the pilot laboratory collected to the all evaluatedresults including associated measurement uncertainties. Then the collected resultsevaluated according to ISO 17043, 2010 are reported by each laboratory as a part of theproficiency test report. Z-scores of the participant laboratories are presented.

The Guide to the expression of measurement uncertainty, (GUM, JCGM 100)and its Supplement 1: propagation of distributions by a Monte Carlomethod, (GUMS1, JCGM 101) are two of the most widely used documents concerningmeasurement uncertainty evaluation in metrology. Both documents describe three phases (a)the construction of a measurement model, (b) the assignment of probability distributionsto quantities, and (c) a computational phase that specifies the distribution for thequantity of interest, the measurand. The two approaches described in these two documentsagree in the first two phases but employ different computational approaches, with the GUMusing linearisations to simplify the calculations. Recent years have seen an increasinginterest in using Bayesian approaches to evaluating measurement uncertainty. The Bayesianapproach in general differs in the assignment of the probability distributions and itscomputational phase usually requires Markov chain Monte Carlo (MCMC) approaches. In thispaper, we summarise the three approaches to evaluating measurement uncertainty and showhow we can regard the GUM and GUMS1 as providing approximate solutions to the Bayesianapproach. These approximations can be used to design effective MCMC algorithms.

Calibration of volumetric proving tanks can be done using different methods. For thecalibration of large proving tanks the master meter method can be used as a goodalternative to the volumetric transfer method or the gravimetric method. When the mastermeter method is used in most cases a positive displacement meter is used. A better optionis to make use a Coriolis mass flow meter as the master meter. Test data is presented of acalibration of a proving tank with a nominal volume of 500 L. Small repeatability figurescan be obtained of consecutive calibration runs with a Coriolis mass flow meter. Also thelinearity of the meter factor curve of the Coriolis mass flow meter makes this a betteroption for the master meter method.

A new comparison system has been constructed for the calibration of capsule-type standardplatinum resistance thermometers (CSPRTs) below 273.16 K at the National Institute ofStandards (NIS-Egypt). The system can compare two CSPRTs at once. A gold plated comparisonblock, in which CSPRTs are mounted for calibration, is made from oxygen-freehigh-conductivity copper. A description of the system and the comparison block along withthe comparison method is given. The standard uncertainty related to the temperaturecontrol of the system is estimated to be 0.04 mK. The calibrated values for CSPRTs andobtained using the comparison system are in good agreement with those obtained by thedirect realization of the low temperature fixed points of the ITS-90 within the combinedstandard uncertainty.

Laser trackers are becoming the tool of choice for large volume dimensional metrologyapplications such as the measurement of aerospace assemblies, power plant structures,civil engineering structures and terrestrial transportation vehicles. A laser tracker is aportable coordinate measuring system that tracks a moving target reflector and measuresthe position of the target in spherical coordinates (r,θ, φ). The metrological performance of a laser trackeris influenced by many factors including: compensation for atmospheric effects, thermalexpansion of the instrument and its mount, thermal distortion of the workpiece or artefactbeing measured, the wavelength of the laser radiation, the internal alignment of thegimbal axes and the linearity and alignment of the internal angular measuring scales. Themost important of these potential error sources, which fundamentally limit the achievableuncertainty, are the internal mechanical and optical alignments and the quality andalignment of the angular scales. Several national and international standards exist or arein the process of being developed for performance verification of laser trackers. ASMEB89.4.19-2006 is one of the established standards used to verify the performance of lasertrackers. The main test relies on measuring a known reference length in a variety ofconfigurations and ranges and comparison of the observed error (laser tracker measuredlength minus reference length) with the specified maximum permissible error (MPE) definedby the manufacturer. The establishment of an ASME B89.4.19 laser tracker verificationfacility at NPL is introduced. We highlight the importance of tracker verification anddiscuss the error sources, which contribute to the tracker measurement uncertainty. Someinitial results obtained using this new facility are presented.

In order to achieve nanometer accuracy, metrologists need to identify the sources oferror and develop solutions to eradicate or minimize their effects. A stabilized low powerdual-frequency laser heterodyne interferometer (ZMI-1000A) designed to measure linear andangular displacement with nominal measurement resolution 1.24 nm and 0.0025 arcsec,respectively, is used to achieve measurement of displacements over different travellingaxes by comparison with the electronically reference measurements of the stage over widerange 500 mm. The repeatability and reversal error of linear stage over the workingdistance have agreed opto-electronically and the positioning uncertainty been reduced. Amultivariable framework was implemented for the x-axis due to the crosscoupling between the forward and backward course of the linear stage. Thermal errorreduction is achieved using environmental temperature control (20 ± 0.2 °C)to help reduce thermal errors.

The optical frequency comb generator (OFCG) is an attractive optical reference source forvarious applications such as optical frequency metrology, precision spectroscopy andtelecommunications [D.J. Jones, S.A. Diddams, J.K. Ranka, A. Stentz, R.S. Windeler, S.T.Cundiff, Science 288, 635–639 (2000); T. Udem, R. Holzwarth, T.W. Hänsch,Nature 416, 233–237 (2002); T.W. Hänsch, J. Alnis, P. Fendel, M. Fischer, C.Gohle, M. Herrmann, R. Holzwarth, N. Kolachevsky, Th. Udem, M. Zimmermann, Philos. Trans.R. Soc. A 363, 2155–2163 (2005)]. In particular, the OFCG can be used assource for absolute frequency measurement, providing a precise ruler for length metrology.In the present work we describe the results of absolute frequency measurements of primarywavelength standards at 633 nm on the sixth components, d, e, f, g, h and i of the R(127)11-5 hyperfine transition of the 127I2 molecule, at the SpanishCentre of Metrology, CEM. The values obtained with a femtosecond frequency comb (FC1500,Menlo Systems) at CEM are compared with the values recommended by the ConsultativeCommittee for Length (CCL) [T.J. Quinn, Metrologia 40, 103–133 (2003)]. Thisdetermination was made by beat frequency method between a femtosecond laser comb and aniodine-stabilized He-Ne laser. The difference between the mean frequency of the sixthcomponents of the standard laser and those of CCL recommended values for the samecomponents was found to be 6.557 kHz.

Computed tomography has entered the industrial world in 1980’s as a technique fornon-destructive testing and has nowadays become a revolutionary tool for dimensionalmetrology, suitable for actual/nominal comparison and verification of geometrical anddimensional tolerances. This paper evaluates measurement results using different measuringstrategies applied in different inspection software packages for volume and surface dataanalysis. The strategy influence is determined by calculating the measurement uncertainty.This investigation includes measurements of two industrial items, an aluminium pipeconnector and a plastic toggle, a hearing aid component. These are measured using acommercial CT scanner. Traceability is transferred using tactile and optical coordinatemeasuring machines, which are used to produce reference measurements. Results show thatmeasurements of diameter for both parts resulted in smaller systematic errors compared todistance and height measurements. It was found that uncertainties of all measurandsevaluated on surface data were generally greater compared to measurements performed onvolume data.

Least squares regression is commonly used in metrology for calibration and estimation. Inregression relating a response y to a predictor x, thepredictor x is often measured with error that is ignored in analysis.Practitioners wondering how to proceed when x has non-negligible errorface a daunting literature, with a wide range of notation, assumptions, and approaches.For the model ytrue = β0 + β1   xtrue,we provide simple expressions for errors in predictors (EIP) estimators \hbox{$\Hat{{\beta }}_{0, {\rm EIP}} $}β̂0, EIP for β0 and \hbox{$\Hat{{\beta }}_{1, {\rm EIP}} $}β̂1, EIP for β1 and for anapproximation to covariance (\hbox{$\Hat{{\beta }}_{0, {\rm EIP}} $}β̂0, EIP, \hbox{$\Hat{{\beta }}_{1, {\rm EIP}} $}β̂1, EIP). It is assumed that there are measured datax = xtrue + ex,andy = ytrue + eywith errors ex in x andey in y and thevariances of the errors ex andey are allowed to depend onxtrue and ytrue, respectively.This paper also investigates the accuracy of the estimated cov(\hbox{$\Hat{{\beta }}_{0, {\rm EIP}} $}β̂0, EIP, \hbox{$\Hat{{\beta }}_{1, {\rm EIP}} $}β̂1, EIP) and provides a numerical Bayesian alternative usingMarkov Chain Monte Carlo, which is recommended particularly for small sample sizes wherethe approximate expression is shown to have lower accuracy than desired.