Accuracy, in measurement

Measurements and Audits. The enabling element of continuous improvement is measurement. An old rule of thumb says that increased accuracy in measuring an energy use ultimately yields a reduction in use equal to 10% of the increased closure of the balance. A basic principle of economics is that any thing that is free is used in excess, ie, an unmetered electrical use is bigger than expected by at least 10%. Metering of the cost elements at each unit in a chemical plant provides effective accountabhity. Measurements should be linked via computer software to production as weh as to weather to result in maximum feedback. 

The Half-micro-nitrometer.—The half-micro-nitrometer used to collect the nitrogen has a capacity of 8-10 c.c., a volume which corresponds to 20-30 mg. of substance. A completely satisfactory degree of accuracy in measuring the gas is attained by graduating in sub-divisions of 0-02 c.c. 

Instruments that can be employed to measure energy barriers in acyl heterocycles should thus be able to follow these interconversion processes that occur in the energy range between 4 and 80 kJ mol". Furthermore, detection of separate conformers in equilibrium is an important intrinsic feature of experimental methods for quantitative population analysis while its sensitivity limits accuracy in measuring biased equilibria. 

Friedel partners under very similar conditions, and always from the same crystal. Diffractometry is ideal for anomalous scattering because of its inherently great accuracy in measuring intensities, and because the diffractometer can be programmed to collect Friedel pairs in succession, thus assuring that the crystal is in the same condition during collection of the two reflections. But diffractometry is slow compared to collecting data with area detectors. 

This reproducibility is important for a high accuracy in measuring diffusivity (see Section 6.1.2). 

The determination of crystal structure in synthetic polymers is often made difficult by the lack of resolution in the diffraction data. The diffuseness of the reflections observed in most x-ray fiber patterns results from the small size and imperfect lattice nature of the polymer crystallites. Resolution of individual reflections is also made difficult from misorientation of the crystallites about the fiber axis. This lack of resolution leads to poor accuracy in measurement of peak positions. In particular, this lack of accuracy makes determination of layer line heights difficult with a corresponding loss of significant figures in evaluation of the repeat distance for the molecular conformation. In the case of helical conformations, the repeat distance may be of considerable length or, as we shall show, indeterminate and, in effect, nonperiodic. This evaluation requires high accuracy in measurements of layer line heights. 

Dynamic testing DMTA, DMA, torsional braid analysis (Enns and Gillham, 1983) is first used as a thermal analysis method to detect the transitions, using dissipation peaks. Certain commercial DMTA instruments have a relatively low accuracy in measuring forces and/or strains. In contrast, they give relatively accurate values of the damping factor tan 5, so that dissipation spectra tan 8 = f (oo, T), are very useful analytical tools. 

We know that with an increase in confidence or its coefficient the t-value also rises, which means that AX also goes up resulting in a decrease of accuracy in determining X. In accord with Eq. (2.26), to maintain accuracy in measuring X, it is nec-... 

Cali, J.P. and Marsh, K.N., An Annotated Bibliography on Accuracy in Measurement, Pure Appl. Chem. 55 (1983) 907-930. 

The difference in level of the mercury surfaces in the limbs, as measured with a metre stick, gives the pressure in the limb attached to the apparatus. The open limb is exposed to atmospheric pressure, which must be measured on the laboratory barometer and allowed for. A good standard of accuracy in measuring pressures is possible with this type of gauge if the mercury and the inside surface of the glass U-tube are clean and the levels are measured with a cathetometer. 

Normally the sensing chips are produced using microlithography and a four point measuring technique is used to achieve high accuracy in measurement [51], How the polymer is laid on top of the four track sensing device is critical (Fig. 

R.S. TREPTOW, Precision and accuracy in measurements. J. Chem. Educ.,... 

Diagnostic ultrasound has advanced to a very exact science, particularly in the field of medical imaging indeed it is this field which has led the drive for increased accuracy in measurements [ 1 ]. Other areas have benefited from such developments for example diagnostic ultrasound can be used in polymer science. A review of this application has been presented by Pethrick in a chapter published previously in this series [2],... 

The calculated and experimental values in Table 6.10 show quite reasonable agreement. The accuracy of these comparisons is limited by use of limiting equivalent conductances instead of the equivalent conductances at the concentrations actually used, imprecise temperature control, and somewhat limited accuracy in measuring the cell constant. Nevertheless, calculations from a table of equivalent conductances provide a useful estimation of expected experimental results. 

To improve accuracy in measuring R, sieving in gels more concentrated than 0.9% (i.e., in the region of convex curvature in Ferguson plots for particles 13-42 nm in R) was measured by using... 

Dunken and Fritzsche (6) have summarized all the equilibrium constant calculations from infrared data used by earlier workers. They have shown that within the limits of accuracy in measurement, agreement can be reached between the results of two methods of calculation which contradict each other in their assumptions. By making infrared measurements at different temperatures, they also show that these chance agreements can come about at one temperature and not at another. Dunken and Fritzsche consider that simplified treatments of the type enumerated by Lussan are only approximations to the truth, and one should always employ a general model of association in which all the associated species (up to a certain maximum size) are present. The authors discuss the evidence for the cyclic dimer form but do not refer specifically to it in their calculations nor do they suggest that any of the higher multimers are cyclic. 

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