Calibrate meaning

An unbroken chain of comparisons/calibrations means that there must be an identified path of assignments of value to calibrators from the calibrator used in the final measurement back to the primary calibrator that is the embodiment (also known as the realization) of the unit. 

Fig. 1 Traceability system for the determination of the most important diagnostic markers in human body fluids in Germany. The clinical reference laboratories at the intermediate level providing calibration means to the routine medical laboratories are accredited as calibration laboratories in the framework of the German Calibration Service (DKD) and are firmly linked to the national metrology institute, PTB, by comparison measurements carried out on actual laboratory samples. Accreditation is in part required by the Federal Physicians Council (BAK) or is voluntary. The traceability system is still under development...

Abstract Current developments in Germany for establishing a traceability system for chemical measurements are reported. The focus is on a dissemination mechanism which employs chemical calibration laboratories accredited within the framework of the German Calibration Service (DKD) and acting as multipliers between the national standards level and the user level by providing the user with calibration means which are traceable to the SI via national standards. At the national standards level, a network of high-level chemistry institutes coordinated by the national metrology institute, PTB, provides the primary references for chemical measurements. 

This secondary or intermediate level has an important multiplier function. It is firmly linked to the national standards and provides traceable calibration means (mainly certified reference materials) and test samples to the workshop level, which consists essentially of chemical testing laboratories (including medical laboratories) which are required to give evidence to their customers that their measurement results are traceable to recognized references. In the case of medical laboratories, the traceability requirement also has a legal background. 

Meeting these stringent requirements enables the chemical calibration laboratories to act as providers of calibration means at the secondary level. This task requires that the value assignment to the reference materials and other calibration means provided to the user is more accurate than the measurement results at the user level need to be. Chemical calibration laboratories also exist in other countries, for example in the Netherlands and in the U.K. 

Calibration means [1] the operation of establishing, under well-specified conditions, the relationship between the values of a quantity indicated by an instrument or a measurement system or and the value of a measure or RM, or the corresponding values of standards. 

Prediction step Note that because the calibration mean-centered data is used, concentration predictions obtained by Equation 5.22 must be un-mean-centered if actual prediction values are to be reported. 

The energy assignment to the peaks of the spectrum is accomplished by calibrating the detector with a source that emits gammas of known energy and intensity. As explained in Sec. 9.10, calibration means to determine the con-... 

Resubstitution of the benzanthracene concentrations reveals perfect fit, that is, the calibration mean squared error (Eq. (6.106)) is almost zero. Estimation of predictions from a single tree by leave-one-out cross-validation reveals a mean squared prediction error of 0.428. A plot of the recovery function for the individual predictions is given in Eigure 6.16a. Further improvement of the model is feasible if again ensemble methods (cf Tree-Based Classification Section) are applied. Figure 6.16b shows the recovery function for a bagged model with a smaller prediction error of 0.337. 

In active sampling procedures, air is drawn through an absorbing or adsorbing medium by a pump in order to trap the gas phase material. It is important that the sampler has an accurate, calibrated means to determine the total volume of the gaseous sample and the rate at which the gas is being sampled. This is most easily accomplished by the use of calibrated mass flow controllers. 

An SEC system can be calibrated relatively simply by plotting the elution volume (or time) of the peak maxima of a series of calibrants with polydispersities (ratio of to M ) of less than 1.1, against their molecular masses. The use of such narrow MMD calibrants means that sensible calibrations will be obtained regardless of which molecular mass average is used for the plot in practice, the manufacturers of these calibrants now usually supply a peak molecular mass to be used in the calibration. How this calibration is defined will be considered later. 

Field calibration means verifying whether an instrument is functioning properly and giving the correct readout within the limits specified by the manufacturer of the span (calibration or cal) gas. 

Here G(f), F(f) and W(f) are Fourier transforms of g(t), f(t) and w(t), respectively. w(t) and W(f) are named the transfer function and the function of frequency response. A calibration of AE sensor is equivalent to determination of function W(f). On the other hand, it implies that fiequency contents of AE waves are usually smeared by function W(f) of AE sensor. Thus, the absolute calibration means quantitative estimation of function w(t) or W0. 

In practice this simple additive model may not describe the situation completely. There are two reasons for this. The first is that the substances of interest may interfere with each other chemically in a way that affects their spectra. The second is that the specimens from real-life sources may well contain substances other than those of interest, which make a contribution to the absorbance. In these cases it is better to use inverse calibration and calibrate with real-life specimens. The term inverse calibration means that the analyte concentration is modelled as a function of the spectrum (i.e. the reverse of the classical method). For the data in Table 8.4 the regression equations take the form q = fooi + + 2/ 2 + + Inverse... 

According to Webster s Ninth Collegiate Dictionary, the verb calibrate means [...] (3) to standardize (as a measuring instrument) by determining the deviation from a standard so as to ascertain the proper correction factors . In addition, the word caliber has as one of its definitions [...] (3b) degree of excellence or importance . 

A poor calibration means that the model is essentially fixed to a single data point, and it will result in a model that responds wildly even to small changes in the input variables. 11 is better to avoid poor calibration even at the expense of not fully matching plant measurements. When this situation happens, it means that there is likely mass imbalance or hydrogen imbalance in the feed and product measurements. It is best to recheck model inputs before attempting any further calibration. 

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