Other Measuring Techniques

The solid-liquid two-phase flow is widely applied in modern industry, such as chemical-mechanical polish (CMP), chemical engineering, medical engineering, bioengineering, and so on [80,81]. Many research works have been made focusing on the heat transfer or transportation of particles in the micro scale [82-88], In many applications, e.g., in CMP process of computer chips and computer hard disk, the size of solid particles in the two-phase flow becomes down to tens of nanometres from the micrometer scale, and a study on two-phase flow containing nano-particles is a new area apart from the classic hydrodynamics and traditional two-phase flow research. In such an area, the forces between particles and liquid are in micro or even to nano-Newton scale, which is far away from that in the traditional solid-liquid two-phase flow. 

For most existing measuring methods, the actual motion of individual nano-particles in two-phase flow cannot be observed easily. Conventional particle image velocimetry (PIV) apparatus can measure the particles in micro scale 

These spherical nano-particles about 55 nm in diameter have a fluorescent material of ruthenium pyridine inside, and the shell of silicon dioxide, as shown in Fig. 36. The excitation wavelength of the ruthenium pyridine is 480 nm and the emission wavelength is 592 nm [81]. In order to get a clear image of nano-particles, the mass concentration of the fluorescent particles should be limited to a very low level. 

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Therefore, the samples are prepared by mixing fluorescent particles solution and silicon dioxide nano-particles solution as shown in Table 1. 

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The brief history, operation principle, and applications of the above-mentioned techniques are described in this chapter. There are several other measuring techniques, such as the fluorometry technique. Scanning Acoustic Microscopy, Laser Doppler Vibrometer, and Time-of-flight Secondary Ion Mass Spectroscopy, which are successfully applied in micro/nanotribology, are introduced in this chapter, too. 

Many years have passed since the early days of AFM, when adhesion was seen as a hindrance, and it is now regarded as a useful parameter for identification of material as well as a key to understanding many important processes in biological function. In this area, the ability of AFM to map spatial variations of adhesion has not yet been fully exploited but in future could prove to be particularly useful. At present, the chemical nature and interaction area of the AFM probe are still rarely characterized to a desirable level. This may be improved dramatically by the use of nanotubes, carbon or otherwise, with functionalized end groups. However, reliance on other measurement techniques, such as transmission electron microscopy and field ion microscopy, will probably be essential in order to fully evaluate the tip-sample systems under investigation. 

One other measurement technique that has been used to measure Kl over a shorter time period, and is thus more responsive to changes in wind velocity, is the controlled flux technique (Haupecker et al., 1995). This technique uses radiated energy that is turned into heat within a few microns under the water surface as a proxy tracer. The rate at which this heat diffuses into the water column is related to the liquid film coefficient for heat, and, through the Prandtl-Schmidt number analogy, for mass as well. One problem is that a theory for heat/mass transfer is required, and Danckwert s surface renewal theory may not apply to the low Prandtl numbers of heat transfer (Atmane et al., 2004). The controlled flux technique is close to being viable for short-period field measurements of the liquid film coefficient. 

The fact that the measured points of Fig. 3.1 lie more closely to the free-draining line, is in accordance with the experience obtained on anionic polystyrenes with other measuring techniques [dynamic oscillatory measurements (115), measurements of normal stresses (776)]. This result is quite surprising since for the description of intrinsic viscosity the non-draining case has clearly been shown to be valid (100). It will be shown below and in Chapter 4 that this inconsistency is in reality a consequence of the fact that the reduction with respect to concentration is less perfect than one would think at a first inspection of Fig. 3.1. 

Peak height due to its simplicity, speed, and inherent measurement precision is the preferred manual method. Chromatographic conditions are much more critical here than in any other measurement technique. Today s instrumentation helps in this regard. However more frequent standardization is the real solution. 

The goal of this chapter is to provide an overview of the measurement of colloidal forces at liquid/Iiquid interfaces, using predominately atomic force microscopy (AFM)-First, some of the types and origins of the relevant colloidal forces are introduced. This is followed by a general description of the operation of AFM at rigid interfaces. The next sections focus on forces at liquid/Iiquid interfaces, beginning with a discussion of other measuring techniques employed at liquid/Iiquid interfaces, followed by a summary of... 

During the test it is important that mechanical breakdowns be avoided, that the test not be interrupted by regular field production cycles, and that maximum use of tracers, pressure falloff measurements, observation wells, and other measurement techniques be employed. 

In addition, other measurement techniques in the linear viscoelastic range, such as stress relaxation, as well as static tests that determine the modulus are also useful to characterize gels. For food applications, tests that deal with failure, such as the dynamic stress/strain sweep to detect the critical properties at structure failure, the torsional gelometer, and the vane yield stress test that encompasses both small and large strains are very useful. 

Some experimental techniques may produce relatively noisy a, tor a, T traces and it may be advisable to introduce some smoothing of the data, as no model is sufficiently sophisticated to allow for temporary small fluctuations. Any reluctance to resort to such a procedure can be weighed against the consideration that the extent of mathematical smoothing can be monitored, while the smooth experimental traces from other measurement techniques may contain an unknown amoimt and type of instrumental damping. 

As with any type of experimental procedure, it is desirable to compare data acquired in field studies with controlled laboratory studies and/or related models. Various comparisons with models, as well as other measurement techniques, have been made with data collected via the dynamic flow-through chamber system. Some results are presented in the following discussion. 

The following tables list the carrier concentrations, Hall mobility, conditions of the growth technique and polytype. In some cases, C-V and other measurement techniques have been employed. 

Alpha counting and alpha spectrometry are the two most common analytical methods for measuring plutonium concentrations in environmental samples. Other measurement techniques available are liquid scintillation, mass spectrometry, and gamma spectrometry. 

Electrical resistivity comes in two different flavours resistivity at initial geometry (subscript IG, p/o), and resistivity including thermal volume expansion (subscript VE, py. The former can be directly determined from the electric signals by rationing the voltage and the current, whereas information about the volume expansion is needed to obtain the latter, by multiplying V/Vq and Physically, electrical resistivity with volume expansion considered is of greater interest because it can be directly compared with data from other measurement techniques, e.g., 4-point measurements. 

Besides wet chemistry, several other measurement techniques are in general use, including gas chromatography and mass spectrometry. However, these techniques are relatively complicated, and in general the gas samples have to be preconditioned before any quantitative analytical measurement. As a consequence, the methods are normally slow moreover, they may suffer from the same problem as any method requiring preconditioning. 

Therefore, the methyl-terminated phosphate signal can be used to show the dependency of the surface composition of the mixed self-assembled monolayers on the molar concentrations of the amphiphile in solution. Figure 8 shows the relative counts for the DDPO4 ion expressed as a function of the solution molar fraction of the OH-terminated molecule (xoh-ddpo,). If taken quantitatively, this would represent a nonlinear dependence similar to the observations based on our other measurement techniques and in that way supports our view of the dependence of adlayer composition on assembly solution composition. However, it has to be admitted that the situation is rather complex in the sense that the adlayer composition and order are changingat the same time. More information on the order of these mixed adlayers is presented elsewhere. ... 

It may be assumed,that a knowledge of the local turbulence data in or near to the flame front could improve this type of correlation, and that the values of the turbulent burning velocity for different distances from the grid, on such a basis of local turbulence parameters, could really be presented by a single straight line. Further experimental efforts using other measuring techniques will be applied to clarify this question. 

As can be seen from their principle of operation (Figure 2.2), thermocouples are particularly suitable for the measurement of temperature differences, there being no need for a thermostat for the reference junction. Series connection into thermopiles, comprising up to 1000 thermocouples, permits the rapid measurement of temperature differences of 10 K, which is not achieved by other measuring techniques. Thus, thermocouples constitute ideal measuring instm-ments for the determination and continuous monitoring or control of minor differences of temperature. They are consequently used in many calorimeters. At temperatures above 1300 K, thermocouples surpass resistance thermometers for absolute temperature measurements because the precision of the latter instruments deteriorates rapidly in this range. The measurement uncertainty is on the order of 1% of the absolute temperature. 

In many cases, or may have values such that the differences Rj — Rj or Si — S2 are small differences of two very large numbers. Such a situation results in a severe loss of accuracy in AR or AS. When this condition occurs, other measurement techniques must be used. 

Figure 7-6. Impedance of pure iron in 0.5 M H2SO4 sdlution without (-0-) and with 100 mM triphenylbencylphosphonium-chloride as inhibitor (-X-) For comparison, values of the polarization resistance Rp derived from other measurement techniques are Rj cyclic voltammet-ric, /fpi galvanostatic, and Rp po-tentiostatic polarization curves, and solution analysis by atomic absorption (AA) (Jiittner et al., 1985).

Even when the determination of the interfacial tension through this method is empirical, the results obtained proved to be very well correlated with the ones obtained by other measuring techniques as sphere and cyUnder tensiometry. The main factors restricting the general apphcabiUty of the drop detachment technique are the lack of suflScient experimental drop correction factor data for < 0.25 and situations... 

FTIR techniques in combination with or as complement to other measurement techniques have been used in a wide range of photochemistry studies on polymers. These include bisphenol-A polycarbonate [173], polycarbonate coatings on mirrors [174], PMMA [175], poly( -butyl acrylate) [176] and polypropylene [177]. DSC and FTIR studies have been used in conjunction to investigate the nature of y-radiation-induced degradation and its effect on the 19°C and 30°C phase transitions in PTFE [178]. IR studies of the hydrolysis of melamine-formaldehyde crosslinked acrylic copolymer films have shown that copolymer-melamine formaldehyde crosslinks are broken and that crosslinks between melamine molecules are formed [179]. The thermal and photo-degradation mechanisms in an IR study of cured epoxy resins were found to be related to the autoxidative degradation processes for aliphatic hydrocarbons [180]. 

Con osition and Physical Properties Many composition measurements are obtained indirecdy. Physical properties such as temperature, viscosity, vapor pressure, electric conductivity, density, and refractive index are measured and used to infer the conposition of a stream, in place of a direct measurement. A number of other measurement techniques have become commonplace for the on-line analysis of composition. These include gas chromatography and mass and infrared spectrometry. These instruments are very accurate but are expensive and often fail to provide the continuous measurements that are required for rapid regulation. 

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