Techniques of Measurement

A. W. Neumann and R. J. Good, in Techniques of Measuring Contact Angles, Surface and Colloid Science, Vol. II, Experimental Methods, R. J. Good and R. R. Stromberg, ed.. Plenum, New York, 1979. 

This subsertion deals with the techniques of measuring pressures, temperatures, velocities, and flow rates of flowing fluids. 

It is worthwhile to present this episode in eonsiderable detail, beeause it eneapsulates very elearly what was new in physieal metallurgy in the middle of the eentury. The elements are an aecurate theory of the effects in question, preferably without disposable parameters and, to check the theory, the use of a technique of measurement (the Snoek pendulum) which is simple in the extreme in construction and use but subtle in its quantitative interpretation, so that theory ineluctably comes into the measurement itself. It is impossible that any handwaver could ever have conceived the use of a pendulum to measure dissolved carbon concentrations ... 

However, I believe that enough has been described to support my contention that modern methods of characterisation are absolutely central to materials science in its modern incarnation following the quantitative revolution of mid-century. That revolution owed everything to the availability of sensitive and precise techniques of measurement and characterisation. 

Confirmation that a thicker tube wall may slightly increase the burn-out flux has been given by Hewitt et al. (H6). These authors have even gone to the extent of showing that not only the burn-out flux, but the wall-film flow rate prior to burn-out as well, is affected by the wall thickness, as shown in Fig. 16. The technique of measuring the film flow-rate has been described in Section II,D. The reason a thicker-walled tube should maintain a higher wall-film flow rate is not clearly understood. 

Neumann AW, Good RJ (1979) Techniques of Measuring Contact Angles. In Good RJ, Stromberg RR (eds) Surf and Coll Sci, vol 1, Plenum, p 31... 

Many other techniques of measuring viscoelastic parameters, such as transient shear, creep and sinusoidally-varying shear, are available. A good description, together with the merits and demerits of each of these techniques, is available in Whorlow(19. ... 

As happens so often in science, a new and more precise technique of measurement led to a major discovery. When scientists first used mass spectrometers they found—much to their surprise—that not all the atoms of a single element have the same mass. In a sample of perfectly pure neon, for example, most of the atoms have mass 3.32 X 10-26 kg, which is about 20 times as great as the mass of a hydrogen atom. Some neon atoms, however, are found to be about 22 times as heavy as hydrogen. Others are about 21 times as heavy (Fig. B.6). All three types of atoms have the same atomic number so they are definitely atoms of neon. 

The technique of measuring the 0+ kinetic energy distribution produced by reaction of He + and 02 showed promise for establishing the existence of HeO+. Experiments with He3 and He4 isotopes and 02 were carried out in the ion source of a mass spectrometer. Retarding potential curves for O + in the two systems were determined, and the com-... 

The calculated lifetimes (Table 4) are several powers of ten larger then those corresponding to usual electric dipolar transitions (10- -10 s). They constitute therefore true predictions which require special techniques of measurements that were available only in recent years. 

The emission methods of EEP detection are based on the ability of some metastable particles (N2(A ZJ, metastable atoms of rare gases) to knock electrons out of the surface of metals [59]. The present-day technique of measuring small currents allows one to record any small fluxes... 

The experimental technique of measuring out the amount of acid and alkali needed for neutralization is termed a titration. 

Experimental Techniques of Measurements of True, Apparent, and Bulk Density... 

The flow rate of fluids is a critical variable in most chemical engineering applications, ranging from flows in the process indnstries to environmental flows and to flows within the hnman body. Flow is defined as mass flow or volume flow per unit of time at specified temperatnre and pressure conditions for a given flnid. This snbsection deals with the techniques of measuring pressure, temperature, velocities, and flow rates of flowing fluids. For more detailed discussion of these variables, consult Sec. 8. Section 8 introduces methods of measuring flow rate, temperature, and pressure. This subsection bnilds on the coverage in Sec. 8 with emphasis on measurement of the flow of fluids. 

An additional difficulty in studies of slow chemisorption is evidenced by the Taylor-Liang technique of measuring adsorption isobars at successively higher temperatures without pumping between runs, a technique that has been reviewed in an earlier volume of this series (8). The ad-sorption-desorption phenomena observed between room temperature and about 150°C. clearly show in this temperature range the existence on the surface of zinc oxide of two types of hydrogen chemisorption (9). 

At present there are three basic techniques of measuring particle velocity, namely free surface velocity (FSV) measurements, electromagnetic velocity (EMV) measurements, and flash X-ray measurements. Before proceeding to describe these techniques, it should be noted that agreement among these techniques is not satisfactory. At present there is no consensus as to which technique is best , nor is there any real understanding as to why these different methods give different results... 

It seems to the present authors that the above-mentioned scheme of the initiation process in the glass matrices can be extended, at least, to the radiation-induced ionic polymerizations in liquid solutions at higher temperatures. This will be verified by rapid techniques of measurement, such as the pulse radiolysis method. 

Since benzo[c]furan is too unstable for the usual techniques of measuring bond lengths and angles its precise geometry remains unknown and various assumed values have been... 

The techniques of measuring drying of stationary products, as on trays, are relatively straightforward. Details may be found in the references made with the data of Figure 9.3. Mass transfer resistances were eliminated by Wenzel through use of superheated steam as the drying medium. 

Another way to state Equation 8.24 is that the voltage across a resistor is proportional to the current through the resistor. These simple relationships are the basis of virtually all techniques of measuring conductance (or resistance) the measurement of the I/E ratio for a conductor yields G directly, while the E/I... 

As happens so often in science, a new and more precise technique of measurement led to a major discovery. When scientists first used mass... 

The average accuracy of the data was 4.9% for volume, 2.5% for mass and 5.6% for the particulate matter levels. Future improvements in our technique of measurement of Ah will permit a decrease in the uncertainty of PMi0 levels to about 4%. Further decreases in the final error are limited by the quality of mass measurements. For example, a decrease of 0.001 g in the uncertainty of mass measurements will reduce the PM10 final error to a value as low as 0.5%. Thus, we are now focusing efforts in the improvement of our weighting procedure, particularly in what concerns ambient conditions for the operation of the analytical balance. 

Little sampling was performed with the cobalt glass since a limited supply of chips was available. The sampling did, however, confirm uniformity. The techniques of measurement are quite straightforward but require some refinements over the cellophane. The orientation of the chips appears to be quite critical. 

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