The Standards

VCCI label, for Voluntary Control Council for Interference) is completely voluntary (as the name itself suggests). But we must realize that all such EMI/EMC/Safety marks, whether required by regional/national laws or not, are increasingly perceived by the market as an indication of product quality. Thus, though in theory some of these may be voluntary, in practice, marketing pressures may make them inevitable. 

As an example of how other countries tend to follow the lead set by Europe and the United States in these matters, take Canada for example. The regulatory Canadian body having jurisdiction over EMI is called Industry Canada. However, its technical requirements are essentially equivalent to those of the FCC. Therefore, if FCC approval 

The ratio c/u is always greater than 1, and is called the index of refraction of the material (through which the wave travels at the speed u). Note that though c is popularly called the velocity of light, it is the same for any electromagnetic wave. It can be shown that c = l/ y/( Xo o) where x0 is the permeability of free space (vacuum or air) and e0 is the permittivity of free space. x0 and e0 are fundamental constants, since they represent the properties of our universe. 

P band (.band S band C band X band Ku band Kband Ka band Millimeter band 

It is well-known from our physics class that if a piece of electronic equipment has a dimension close to 74, it can end up radiating (or receiving) the corresponding frequency very effectively. This is the principle behind a radio antenna. Note that although a TV antenna is symmetrical around the point where it connects to the cable and has a total physical length of 72, it actually has only 74 (effective receiving length) on each side. 

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For such components, as the composition of the solution approaches that of the pure liquid, the fugacity becomes equal to the mole fraction multiplied by the standard-state fugacity. In this case,the standard-state fugacity for component i is the fugacity of pure liquid i at system temperature T. In many cases all the components in a liquid mixture are condensable and Equation (13) is therefore used for all components in this case, since all components are treated alike, the normalization of activity coefficients is said to follow the symmetric convention. ... 

According to Equation (14), the fugacity of component i becomes equal to the mole fraction multiplied by the standard-... 

Henry s constant is the standard-state fugacity for any component i whose activity coefficient is normalised by Equation (14). ... 

In a binary liquid solution containing one noncondensable and one condensable component, it is customary to refer to the first as the solute and to the second as the solvent. Equation (13) is used for the normalization of the solvent s activity coefficient but Equation (14) is used for the solute. Since the normalizations for the two components are not the same, they are said to follow the unsymmetric convention. The standard-state fugacity of the solvent is the fugacity of the pure liquid. The standard-state fugacity of the solute is Henry s constant. 

The use of Henry s constant for a standard-state fugacity means that the standard-state fugacity for a noncondensable component depends not only on the temperature but also on the nature of the solvent. It is this feature of the unsymmetric convention which is its greatest disadvantage. As a result of this disadvantage special care must be exercised in the use of the unsymmetric convention for multicomponent solutions, as discussed in Chapter 4. 

The standard-state fugacity of any component must be evaluated at the same temperature as that of the solution, regardless of whether the symmetric or unsymmetric convention is used for activity-coefficient normalization. But what about the pressure At low pressures, the effect of pressure on the thermodynamic properties of condensed phases is negligible and under such con-... 

We find that the standard-state fugacity fV is the fugacity of pure liquid i at the temperature of the solution and at the reference pressure P. ... 

In some cases, the temperature of the system may be larger than the critical temperature of one (or more) of the components, i.e., system temperature T may exceed T. . In that event, component i is a supercritical component, one that cannot exist as a pure liquid at temperature T. For this component, it is still possible to use symmetric normalization of the activity coefficient (y - 1 as x - 1) provided that some method of extrapolation is used to evaluate the standard-state fugacity which, in this case, is the fugacity of pure liquid i at system temperature T. For highly supercritical components (T Tj,.), such extrapolation is extremely arbitrary as a result, we have no assurance that when experimental data are reduced, the activity coefficient tends to obey the necessary boundary condition 1... 

Enthalpies are referred to the ideal vapor. The enthalpy of the real vapor is found from zero-pressure heat capacities and from the virial equation of state for non-associated species or, for vapors containing highly dimerized vapors (e.g. organic acids), from the chemical theory of vapor imperfections, as discussed in Chapter 3. For pure components, liquid-phase enthalpies (relative to the ideal vapor) are found from differentiation of the zero-pressure standard-state fugacities these, in turn, are determined from vapor-pressure data, from vapor-phase corrections and liquid-phase densities. If good experimental data are used to determine the standard-state fugacity, the derivative gives enthalpies of liquids to nearly the same precision as that obtained with calorimetric data, and provides reliable heats of vaporization. 

For pure liquids the standard-stare fugacity is represented... 

The diagonal elements of this matrix approximate the variances of the corresponding parameters. The square roots of these variances are estimates of the standard errors in the parameters and, in effect, are a measure of the uncertainties of those parameters. 

At temperatures above those corresponding to the highest experimental pressures, data were generated using the Lyckman correlation all of these were assigned an uncertainty of 5% of the standard-state fugacity at zero pressure. Frequently, this uncertainty amounts to one half or more atmosphere for the lowest point, and to 1 to 5 atmospheres for the highest point. 

H. The next cards provide estimates of the standard deviations of the experimental data. At least one card is needed with non-zero values. Units are the same as those of the VLE data. FORMAT(4f10.2,I2). ... 

Standard-state fugacities at zero pressure are evaluated using the Equation (A-2) for both condensable and noncondensable components. The Rackett Equation (B-2) is evaluated to determine the liquid molar volumes as a function of temperature. Standard-state fugacities at system temperature and pressure are given by the product of the standard-state fugacity at zero pressure and the Poynting correction shown in Equation (4-1). Double precision is advisable. 

Many catalysts have been used but the standard catalysts are generally mixtures of silica and alumina or natural or synthetic aluminium silicate zeolites. 

In thermodynamic terms the equilibrium constant is related to the standard chemical potential by the equation... 

Thermodynamic quantities which refer to the standard state are denoted by superscript zeros ( ), e.g. AG/, AH/, AS/, the subscript denoting the temperature T of the system. 

A major contribution to the Pelican Social History of Britain, which will undoubtedly be the standard work for students of modern Britain for many years to come - The Times Educational Supplement... 

Because of their diversity and complexity as well as the gradual internationalization of the different standards, it has proven necessary to standardize the methods of sample preservation, handling, fractionation, and analysis throughout the chain of separation and treatment. All these stages are the object of precise protocols established by official national and international organizations. They describe in as minute detail as possible the procedures employed not only for each analysis but very often giving different procedures for the same analysis in different matrices. These are the standards or standardized methods discussed in Chapter 7. 

An important application of this type of analysis is in the determination of the calculated cetane index. The procedure is as follows the cetane number is measured using the standard CFR engine method for a large number of gas oil samples covering a wide range of chemical compositions. It was shown that this measured number is a linear combination of chemical family concentrations as determined by the D 2425 method. An example of the correlation obtained is given in Figure 3.3. 

We would add that this method is applicable to other gas oil cuts by ultimately changing if necessary the standards for refractometric response. 

Group the component in a petroleum fraction, which is possible if the normal boiling temperature and the standard specific gravity are known. This method gives correct results when the chemical structure is simple as in the case of a paraffin or naphthene. 

The standard specific gravity is the ratio of the density of a hydrocarbon at 15.55°C (60°F) to that of water at the same temperature. It differs from the specific gravity d] which is the ratio of the density of a hydrocarbon at 15°C to that of water at 4°C. 

The standard specific gravity can be estimated from using the followinc relation ... 

It is common that a mixture of hydrocarbons whose boiling points are far enough apart petroleum cut) is characterized by a distillation curve and an average standard specific gravity. It is then necessary to calculate the standard specific gravity of each fraction composing the cut by using the relation below [4.8] ... 

Using the principle of corresponding states requires knowledge of pseudo-critical constants of petroleum fractions these should be estimated starting from characteristic properties which are the normal boiling temperature and the standard specific gravity. 

For petroleum fractions, the values should be calculated starting with the standard specific gravity accor( ing to the relation ... 

Calculation of the atmospheric TBP is rapid if it can be assumed that this distillation is ideal (which is not always the case in reality). It is only necessary to arrange the components in order of increasing boiling points and to accumulate the volumes determined by using the standard specific gravity. 

The criterion retained up to now in the specifications is not the true vapor pressure, but an associated value called the Reid vapor pressure, RVP. The procedure is to measure the relative pressure developed by the vapors from a sample of motor fuel put in a metallic cylinder at a temperature of 37.8°C. The variations characteristic of the standard method are around 15 millibar in repeatability and 25 millibar in reproducibility. 

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