Field measurements measured results

Even thought a significant difference does not exist between the linear regression uncertainty and the overall uncertainty, this approach takes into account all sources of uncertainty and underlines the link between the field measurement results and the values of the standards used for the instrument s calibration. The ratio uncertainty between the CRMs and the photometer involved, gives the strength of the traceability link. Moreover, the evaluation of the overall uncertainty in spectrochemical measurements must take into account the steps of the spectrometric measurement process. 

The gas emission in mined working faces, field measure results and theoretical analysis showed that the gas in 33207 working face is mainly from mining coal seams, adjacent seams (including wall rocks), and gobs, the gas from adjacent seam... 

The model of motion study for the skips (65 ft, 4000 Ipm) was extrapolated from the existing setting (48 ft, 3300 fpm) that has been correlated with the field tests. The field measurement results of skip movement (clearance), Coriofls effect, guide rope with tension from cheese weight, and air pressure during the skip travels were incorporated in the model. Minimum clearance between the skips during the travels was predicted. No skip collision was predicted to occur under the tested conditions. 

The available field measurement results exhibit a wide range of wave setup to wave height ratios. Some of this variability is undoubtedly due to the effect of profile slope, which is not accounted for explicitly in some of the analyses and part is due to the effect of wave-breaking in depths greater than the shallow water limit. 

FIELD MEASUREMENT RESULTS FOR LEAD IN PAINT FILMS... 

A detailed method of determining pressure coefficients is to perform experiments with a wind tunnel facility. Cochran and Cermak compared wind tunnel pressure coefficient measurements with field measures on a test building and found excellent results, with the exception of small areas beneath the vortices near the upwind roof corner for winds approaching at 45 . For infiltration and natural ventilation designs, wind tunnel results should be sufficiently accurate. 

Photodiodes produce an electric field as a result of pn transitions. On illumination a photocurrent flows that is strictly proportional to the radiation intensity. Photodiodes are sensitive and free from inertia. They are, thus, suitable for rapid measurement [1, 59] they have, therefore, been employed for the construction of diode array detectors. 

Evidence from field measurements indicated slow decay near the source of contamination but persistence further downstream. This was consistent with the results of laboratory experiments that showed only slow biodegradation of MTBE under aerobic condition (Borden et al. 1997). 

In addition to the requirements regarding traceability of measurement results, the measurement methods employed should represent "state-of-the-art in the particular field. Failing to do so would lead to a reference material with an uncertainty that has become too large to serve as a quality control. The better the methods perform in terms of uncertainty and traceability, the better the reference material will serve the interests of the (potential) users. 

The hypothesis of a normal distribution is a strong limitation that should be always kept in mind when PCA is used. In electronic nose experiments, samples are usually extracted from more than one class, and it is not always that the totality of measurements results in a normally distributed data set. Nonetheless, PCA is frequently used to analyze electronic nose data. Due to the high correlation normally shown by electronic nose sensors, PCA allows a visual display of electronic nose data in either 2D or 3D plots. Higher order methods were proposed and studied to solve pattern recognition problems in other application fields. It is worth mentioning here the Independent Component Analysis (ICA) that has been applied successfully in image and sound analysis problems [18]. Recently ICA was also applied to process electronic nose data results as a powerful pre-processor of data [19]. 

In order to answer these questions, laboratory experiments were compared with field measurements in a local river (Muller and Sigg, 1990). Laboratory experiments with the centrifuged particulate matter, isolated from a river, were used. The results obtained by titrating a metal solution with a suspension of the centrifuged particles were interpreted in terms of binding capacities and conditional stability constants (Fig. 11.5). 

For a range of typical meteorological conditions this formulation results in diffusivities of 0(50-100 m sec" ). Some typical results (given in Table VIII) are in quite close agreement with field measurements and the formulas recommended by Briggs (1974) for city conditions. In the above model, Kyy varies as a function of the surface conditions at different spatial locations but is assumed to be invariant with height. 

In some fields where measurement results are used, it is not yet common practice to explicitly define decision rules. The best way to do it, is in the product specification or the regulation. Wliere this is not the case, it should be clarified as part of the analytical requirement by the customer. When compliance or non-comphance is reported, it should be clear to all involved parties, which decision rules were used. 

Different soils show varying rates of degradation. Phelan and Webb s summary included both laboratory and field measurements from multiple sources. Results from laboratory and field results correlate reasonably well. Continuing their summary [1, p. 36] ... 

Table 9.1 lists some of the theoretical relationships from Chapter 8, for example, and the difficulties in applying these relationships to field situations. Eventually, application to the field comes down to a creative use of laboratory and field measurements, with a good understanding of the results that theory has given us and to make sure that we do not violate some of the basic principles of the theoretical relationships. 

A technique that has been used in laboratory studies for oxides of nitrogen and shows promise for field measurements is resonance-enhanced multiphoton ionization (REMPI) (Guizard et al., 1989 Lemire et al., 1993 Simeonsson et al., 1994). For example, Akimoto and co-workers (Lee et al., 1997) have reported a REMPI system in which a (1 + 1) two-photon absorption of light at 226 nm by NO results in ionization (vide supra). They report a detection limit of 16 ppt in their laboratory studies. Other oxides of nitrogen such as NOz and HN03 can also photodissociate in the... 

If there is any doubt about whether 100% of the analyte is presented to the measuring system or that the response of the calibrated system leads to no bias, then the assumptions must be tested during method validation and appropriate actions taken. If a series of measurements of a CRM (not used for calibration) leads to the conclusion that there is significant bias in the observed measurement result, the result should be corrected, and the measurement uncertainty should include the uncertainty of the measurement of the bias. If the bias is considered insignificant, no correction need be made, but measuring the bias and concluding that it is zero adds uncertainty (perhaps the bias was not really zero but is less than the uncertainty of its measurement). One approach to measurement uncertainty is therefore to include CRMs in the batch to be used to correct for bias, and then the uncertainty of estimation of bias, which includes the uncertainty of the quantity value of the CRM, is combined with the within-laboratory reproducibility. In some fields of analysis it is held that routine measurement and correction for bias... 

Figure 7.9. A possible metrological traceability chain for the result of a measurement of protein in a sample of grain. aTris = 2-amino-2-hydroxymethyl-1,3-propanediol b Dumas apparatus is calibrated using tris CRM and grain samples are certified in an interlaboratory study cthe master instruments measure grain samples to act as the grower s calibrator for field measurements.

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