Measurement absolute

It would be tlierefore thus easy to obtain in real time, on computer, tlie image of a long standard defect that is to even to produce the impedance variation observed. It would be thus possible to realize the control by absolute measures and to avoid the recourse to standard defects. 

It means that we may determine the cross section of the defect by measuring the variation of the inductance. It is an absolute measurement because the coefficient depends only of... 

Laser-based profilometry is now being applied to a wide variety of both NDT and Quality Control gauging applications. In the world of NDT, the primary interest is in the details associated with surface topography or deformation of a particular component. Laser-based profilometry systems are commonly used to inspect surfaces for defects such as pitting, corrosion, deformation and cracking. Quality control gauges are used for absolute measurement of dimensions, such as the diameter and thickness of a given part. 

The absolute measurement of areas is not usually usefiil, because tlie sensitivity of the spectrometer depends on factors such as temperature, pulse length, amplifier settings and the exact tuning of the coil used to detect resonance. Peak intensities are also less usefiil, because linewidths vary, and because the resonance from a given chemical type of atom will often be split into a pattern called a multiplet. However, the relative overall areas of the peaks or multiplets still obey the simple rule given above, if appropriate conditions are met. Most samples have several chemically distinct types of (for example) hydrogen atoms within the molecules under study, so that a simple inspection of the number of peaks/multiplets and of their relative areas can help to identify the molecules, even in cases where no usefid infonnation is available from shifts or couplings. 

The accurate and absolute measurement of the distance, D, between the surfaces is central to the SFA teclmique. In a typical experiment, the SFA controls the base position, z, of the spring and simultaneously measures D, while the spring constant, k, is a known quantity. Ideally, the simple relationship A F(D) = IcA (D-z ) applies. Since surface forces are of limited range, one can set F(D = go) = 0 to obtain an absolute scale for the force. Furthennore, SF(D = cc)/8D 0 so that one can readily obtain a calibration of the distance control at large distances relying on an accurate measurement of D. Therefore, D and F are obtained at high accuracy to yield F(D), the so-called force versus distance cur >e. 

The absolute measurement of the distance, D, between the surfaces is central to the SFA teclmique. In interferometric SFAs, it is realized tluough an optical method called multiple beam interferometry (MBI), which has been described by Tolansky [47]. 

A low-energy electron beam can also be obtained using a field emission tip and used in the field emission retarding-potential method. This combination provides an absolute measure of the sample work fiinction and the resolution is excellent [52]. 

In practical appHcations, diffraction instmments may exhibit certain problems. Eor example, there may be poor resolution for the larger droplets. Also, it is not possible to obtain an absolute measure of droplet number density or concentration. Furthermore, the Fraunhofer diffraction theory cannot be appHed when the droplet number density or optical path length is too large. Errors may also be introduced by vignetting, presence of nonspherical... 

As with RBS, the simplest and most precise measurement that ERS can provide is the absolute measure of total hydrogen content ( H and/or H) within a surface layer or film of thickness less than a few thousand angstroms. When the layer is thin, this is determined from the total number of events, or yield Ysummed over the elastic recoil spectral peak. The yield may be expressed as... 

With these facts in mind, it seems reasonable to calculate the pore volume from the calibration curve that is accessible for a certain molar mass interval of the calibration polymer. A diagram of these differences in elution volume for constant M or AM intervals looks like a pore size distribution, but it is not [see the excellent review of Hagel et al. (5)]. Absolute measurements of pore volume (e.g., by mercury porosimetry) show that there is a difference on principle. Contrary to the absolute pore size distribution, the distribution calcu-... 

It would appear that measurement of the integrated absorption coefficient should furnish an ideal method of quantitative analysis. In practice, however, the absolute measurement of the absorption coefficients of atomic spectral lines is extremely difficult. The natural line width of an atomic spectral line is about 10 5 nm, but owing to the influence of Doppler and pressure effects, the line is broadened to about 0.002 nm at flame temperatures of2000-3000 K. To measure the absorption coefficient of a line thus broadened would require a spectrometer with a resolving power of 500000. This difficulty was overcome by Walsh,41 who used a source of sharp emission lines with a much smaller half width than the absorption line, and the radiation frequency of which is centred on the absorption frequency. In this way, the absorption coefficient at the centre of the line, Kmax, may be measured. If the profile of the absorption line is assumed to be due only to Doppler broadening, then there is a relationship between Kmax and N0. Thus the only requirement of the spectrometer is that it shall be capable of isolating the required resonance line from all other lines emitted by the source. 

Tai, C.-K. and Wunsch, C. (1983). Absolute measurement by satellite altimetry of dynamic topography of the Pacific Ocean. Nature 301,408-410. 

Many publications use an absolute measure that denotes water security, frequently referring to an index that identifies a threshold of 1,700 CM per capita per year of renewable water, based on estimates of water requirements in the household, agricultural, industrial, and energy sectors as well as the needs of the enviromnent. Countries whose renewable water supplies cannot sustain this figure experience water stress. When supply falls below 1,000 m per capita per year, a country is said to experience water scarcity, and below 500 m per capita per year, absolute scarcity. However, these terms are easy to misinterpret, because they do not take into account possibilities for trade in agricultural products, efficiency of water use in agriculture, and other variables, and thus obscure the primacy of economic demand rather than physical need in determining water use [3-5]. 

Partitioning or cell-based methods provide an absolute measure of the chemical space covered by a collection of compounds. They are based on the definition of a low-dimensional chemistry space, for example, one based on a small number of physicochemical properties such as molecular weight, calculated logP, and number of hydrogen bond donors [45]. Each property defines an axis of the chemistry-space. The range of values for each property is divided into a set of bins, and the combinatorial product of all bins then defines the set of cells or partitions that make up the space. 

For all of these reasons, neuroradiologists and stroke neurologists often interpret perfusion maps not by absolute measurement of perfusion levels, but by... 

Here, Q is the heat energy input per area p and Cp are the density and specific heat capacity, respectively and indices g, d, and s refer to the gas, metal, and liquid sample layers, respectively. With Eq. (106), the thermal conductivity of the sample liquid is obtained from the measured temperature response of the metal without knowing the thermal conductivity of the metal disk and the thickness of the sample liquid. There is no constant characteristic of the apparatus used. Thus, absolute measurement of thermal conductivity is possible, and the thermal conductivities of molten sodium and potassium nitrates have been measured. ... 

NIS provides an absolute measurement of the so-called normal mode composition factors that characterize the extent of involvement of the resonant nucleus in a given normal mode. On the basis of the analysis of experimental NIS data, one can therefore construct a partial vibrational density of states (PVDOS) that can be... 

Absolute measurements by fundamental quantities like Faraday constant and quotients of atomic and molar masses, respectively (coulom-etry, electrogravimetry, gravimetry, gas volumetry)... 

Depending on the type of relationships between the measured quantity and the measurand (analytical quantity) it can be distinguished (Danzer and Currie [1998]) between calibrations based on absolute measurements (one calibration is valid for all1 on the basis of the simple proportion y = b x, where the sensitivity factor b is a fundamental quantity see Sect. 2.4 Hula-nicki [1995] IUPAC Orange Book [1997, 2000]), definitive measurements (b is given either by a fundamental quantity complemented by an empirical factor or a well-known empirical (transferable) constant like molar absorption coefficient and Nernst factor), and experimental calibration. 

No theory can possibly take into account the arrangement of a real heat-flow calorimeter in all its details. Theoretical models of heat-flow calorimeters, which are necessarily simplified versions of the actual instruments, will therefore be used in the following calculations. It must be remarked that because of the limitations of the theory, no absolute measurements can be made with a heat-flow calorimeter, nor with any calorimeter. It is possible, however, to compare successive measurements with precision. A calorimetric study necessarily involves the calibration of the calorimeter and, upon this operation, depends the accuracy of the whole series of measurements. 

R. Bezman and L. R. Faulkner discussed theoretical and practical aspects for measurements of the efficiencies of chemiluminescent electron transfer reactions 189>. They also performed absolute measurements of the chemiluminescence of the fluoranthene- 10-methyl-phenothiazine system 211h... 

The experimental realization of a Carnot cycle to measure the temperature T is unusual. The coincidence of the thermodynamic temperature T with the temperature read by a gas thermometer, for example, allows the use of such thermometer to know T. As we shall see, also other laws of physics relating T with physical parameters other than heat can be used to get an absolute measure of T. 

Parallax calculations are the only absolute measure of distance... 

The ion-beam analysis techniques described in preceding sections have been applied in many investigations of hydrogen in semiconductors. In this section we will mention studies in two areas where ion-beam analysis of H has made a significant contribution these are the thermal release and redistribution of implanted hydrogen and the absolute measurement of IR absorption cross sections in a-Si H. In addition, we will mention a developing field, the study of hydrogen in interfaces. 

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