Measurement rules

There are several general rules about making measurements. These rules are standard regardless of the type of equipment being used, material being studied, or the measurement units being used. 

The quality of the measurement is only as good as the last clearly read number. No matter how obvious an estimated number may seem, it is not as reliable as the one your equipment actually provides for you. For example, see Fig. 2.1 and Fig. 2.2. If you want greater accuracy in your readings, you need better equipment, which provides more precise measurements. One safe way to indicate greater accuracy is to qualify a number. In the case of Fig. 2.1, you could write 6.2 0.2. The selection of 0.2 is somewhat arbitrary, as the length is obviously greater than 6.0, yet smaller than 6.5. 

It may be tempting to read the length of the block as 6.2 units, but an accurate measurement would be 6 units. 

Be aware of equipment error. Measuring tools can be improperly cali- 

Name Symbol Power Name Symbol Power 

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Symmetry of superconducting state. No Hebel-Slichter coherence peak was observed in either k -(ET)2Cu(NCS)2 or c-(ET)2Cu[N(CN)2]Br in NMR measurements, ruling out a BCS s-wave state. The symmetry of the superconducting state of c-(ET)2Cu(NCS)2 had been controversially described as normal BCS-type or non-BCS type however, scanning tunneling spectroscopy showed f-wave symmetry with line nodes along the direction near ti/4 from k - and Kc-axes [228, 229], and thermal conductivity measurements were consistent with this result [230]. c-(ET)2Cu [N(CN)2]Br showed the same symmetry [231]. 

Mechanism is a technical term, referring to a relatively detailed, microscopic description of a chemical transformation, which, nevertheless, slill falls far short of a complete dynamical description at the atomic level. A mechanism for a reaction is sufficient to predict the macroscopic rale law til the reaction This deductive process is valid only in one direction, i.e,. an unlimited number of mechanisms are consistent with any measured rule law. A successful kinetic study postulates a mechanism, derives the rate law. and demonstrates that the rale law is sufliciem to explain experimental data over some range of conditions, New data may be discovered later that prove inconsistent with the assumed tuic law and lequite that a new mechanism he postulated. Mechanisms stale, in particular, what molecules actually react in an elementary step and what products these produce. An overall chemical equation tnuy involve a variety of intermediates, and the mechanism specifies those intermediates. 

For porous solids such as coal, there are five different density measurements true density, apparent density, particle density, bulk density, and in-place density. The true density of coal is the mass divided by the volume occupied by the actual, pore-free solid in coal. However, determining mass of coal may be deemed as being rather straightforward, but determining volume presents some difficulties. Volume, as the word pertains to a solid, cannot be expressed universally in a simple definition. Indeed, the method used to determine volume experimentally, and subsequently, the density, must be one that applies measurement rules consistent with the adopted definition. 

The zeros in the numbers of parts (b) and (c) do not affect the magnitude they must therefore show something about the precision of the measurements (rule 3). I... 

Figure 3 Sample holders made of Dehin for Mossbauer spectroscopy of powders (left) and frozen solutions (right). The measurement rule has units of centimeters...

For years Celsius thermometers were referred to as Centigrade thermometers. However, in 1948, the Ninth General Conference of Weights and Measures ruled that degrees centigrade would be referred to as degrees Celsius in his honor. The Celsius scale is still used today by most scientists. 

Many kinetic studies of the thermal decomposition of silver oxalate have been reported. Some ar-time data have been satisfactorily described by the cube law during the acceleratory period ascribed to the three-dimensional growth of nuclei. Other results were fitted by the exponential law which was taken as evidence of a chain-branching reaction. Results of both types are mentioned in a report [64] which attempted to resolve some of the differences through consideration of the ionic and photoconductivities of silver oxalate. Conductivity measurements ruled out the growth of discrete silver nuclei by a cationic transport mechanism and this was accepted as evidence that the interface reaction is the more probable. A mobile exciton in the crystal is trapped at an anion vacancy (see barium azide. Chapter 11) and if this is further excited by light absorption before decay, then decomposition yields two molecules of carbon dioxide ... 

Pure VSb04 has been prepared and shown to have a structure similar to rutile, with a random distribution of Sb and V atoms. Magnetic measurements rule out the Sb V 04 formulation but it is not possible to make a decision between the alternatives Sb V 04 and Sb V 04. The ferroelectric properties of synthetic SbNb04 prepared by a hydrothermal method have been studied, and a phase diagram for the Li(Taj,Sbi a )03 system has been constructed from A -ray data, ... 

Nonbarometric measuring rules out the effects of site elevation, since vacuum pumps still operate with no losses at high elevations. The custo-... 

Electrochemical measurements ruled out ion-association between lie and H+ (namely, protonation of the POM). Quantitative analysis of rate expressions for possible mechanisms then showed CPET to be the only plausible mechanism that could result in a linear dependence of rates on [H+]. The CPET pathway was found to be first-order in [H+] (as well as in [O2] and [lie]), with the proton involved as a reactant (Eq. 12.11). 

To obtain information on the intrinsic conductivity of the film, several methods were applied. Optical conductivity of the doped film was estimated from IR measurements as microwave conductivity measurements and thermoelectric power measurements ruled out the hypothesis of a metal-like behaviour of the film [47]. Measurements of the Hall effect were also attempted [48]. The effect of electron beam irradiation on the film conductivity showed the possibilities for application to the area of microlithography [49]. 

For the refiner, the main problem is to meet the specifications for kinematic viscosity and sulfur content. Dilution by light streams such as home-heating oil and LCO, and selection of feedstocks coming from low-sulfur crude oils give him a measure of flexibility that will nevertheless lead gradually to future restrictions, most notably the new more severe antipollution rules imposing lower limits on sulfur and nitrogen contents. 

This rule is justified by the need to limit the benzene emissions from evaporation (Tims, 1983) Figure 5.25 shows that emissions increase linearly with the benzene content of the fuel. It is noteworthy that current legislation limits the measured evaporation to 2 g per test conducted in accordance with a standard procedure (Sealed Housing for Evaporative Determination, or SHED). Yet for a fuel containing 5% benzene, an evaporation of 0.7 g benzene /test is observed. 

The accuracy of the presented methods was verified using test pipes with various diameters and wall thickness of which the wall thickness was measured independently using a slide-rule. Both on film and on the monitor the wall thickness could be determined within an accuracy of ca. 0.2 - 0.3 mm. 

For all the probes we design a specific and simple measurement set-up. The figure 2 illustrates the three different targets we made for the illustrated probes, following the rules ... 

Finally, under the heading Specific pressure equipment requirements specific requirements are set out for equipment with a risk of overheating, for piping and, last but not least, specific quantitative requirements which set out a series of safety factors for certain pressure equipment. These latter provisions apply as a general rule which means that a manufacturer or a harmonised standard may deviate from these factors if it can be demonstrated that appropriate measures have been taken to achieve an equivalent level of safety. 

The main purposes of the System of accreditation is to ensure reproducibility of measurements, harmonisation of rules and procedures of the National system of accreditation with guidelines of international organizations and national systems of different countries, creation of conditions for mutual recognition of the results of testing, calibration, attestation. 

It may be realised by means of definite complex of intereonneeted and interrelated common rules and norms direeted to the assurance of traceability and uniformity of measuring equipment, NDT equipment including. In another words NDT equipment must be metrologically supported. 

While the phase rule requires tliree components for an unsymmetrical tricritical point, theory can reduce this requirement to two components with a continuous variation of the interaction parameters. Lindli et al (1984) calculated a phase diagram from the van der Waals equation for binary mixtures and found (in accord with figure A2.5.13 that a tricritical point occurred at sufficiently large values of the parameter (a measure of the difference between the two components). 

If we consider the optical response of a molecular monolayer of increasing surface density, the fomi of equation B 1.5.43 is justified in the limit of relatively low density where local-field interactions between the adsorbed species may be neglected. It is difficult to produce any rule for the range of validity of this approximation, as it depends strongly on the system under study, as well as on the desired level of accuracy for the measurement. The relevant corrections, which may be viewed as analogous to the Clausius-Mossotti corrections in linear optics, have been the... 

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 transition between levels coupled by the oscillating magnetic field B corresponds to the absorption of the energy required to reorient the electron magnetic moment in a magnetic field. EPR measurements are a study of the transitions between electronic Zeeman levels with A = 1 (the selection rule for EPR). 

According to an elegant remark by Davies [5], "Modem scientific data handling is multitechnique, multisystem, and manufacturer-independent, with results being processed remotely from the measuring apparatus. Indeed, data exchange and storage are steps of the utmost importance in the data acquisition pathway. The simplest way to store data is to define some special format (i.e., collection of rules) of a flat file. Naturally, one cannot overestimate the importance of databases, which are the subject of Chapter 5 in this book. Below we discuss three simple, yet efficient, data formats. 

The Cahn-Ingold-Prelog (CIP) rules stand as the official way to specify chirahty of molecular structures [35, 36] (see also Section 2.8), but can we measure the chirality of a chiral molecule. Can one say that one structure is more chiral than another. These questions are associated in a chemist s mind with some of the experimentally observed properties of chiral compounds. For example, the racemic mixture of one pail of specific enantiomers may be more clearly separated in a given chiral chromatographic system than the racemic mixture of another compound. Or, the difference in pharmacological properties for a particular pair of enantiomers may be greater than for another pair. Or, one chiral compound may rotate the plane of polarized light more than another. Several theoretical quantitative measures of chirality have been developed and have been reviewed elsewhere [37-40]. 

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