Systematic Units

However, empirical units have left a lasting impression on terminology, and while still employed from time to time in providing names for base stocks (e.g., 100N, 250N), their actual viscosity measurements and their ranges on specification sheets are measured in systematic units and converted to empirical 

Increasingly used are those corresponding to the SI system (International System of Units), where the newton (N, kg m/s2) is the unit of force, and the pascal (Pa, N/m2) is the unit of pressure. Therefore, 

Therefore, to summarize, in the SI system, dynamic viscosity is expressed as pascal seconds and kinematic viscosity is expressed as square meters per second. In practice, dynamic viscosities are reported as millipascal seconds (mPa-s). Base stock viscosities are usually reported as kinematic viscosities. 

In the centimeter-gram-second (CGS) system, where the smaller units of the centimeter and gram are employed, the unit of dynamic viscosity is the poise  

For practical use, the poise is too large a unit the unit normally seen is the centipoise (cP). 

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The English system equivalent is a pressure of 14.7 Ib/in (poimds per square inch) or 29.9 in Hg (inches of mercury). A recommended, yet less frequently used, systematic unit is the pascal (or kUopascal), named in honor of Blaise Pascal, a seventeenth-century French mathematician and scientist ... 

Viscosity measurements are expressed in either systematic or empirical units both are used, but the current trend is very much toward using systematic units. 

Unit of Measurement n Systematic and non-systematic units for measuring physical quantities, including metric ad US pound-inch systems. Also called units. 

Red lead is insoluble in water. Like lead(II) oxide it can readily be reduced to lead. The structure of the solid, as the systematic name suggests, consists of two interpenetrating oxide structures, in which each Pb atom is surrounded octahedrally by six oxygen atoms, and each Pb" by three (pyramidal) oxygen atoms, the oxygen atoms being shared between these two units of structure. With dilute nitric acid the lead(ll) part dissolves, and the lead(IV) part precipitates as lead(IV) oxide ... 

The first attempt to formulate a systematic nomenclature for polymers was based on the smallest repeating stmctural unit it was pubHshed in 1952 by a Subcommission on Nomenclature of the lUPAC Commission on Macromolecules (95). The report covered not only the naming of polymers, but also symbology and definitions of terms. However, these nomenclature recommendations did not receive widespread acceptance. Further progress was slow, with a report on steric regularity in high polymers pubHshed in 1962 and updated in 1966 (96). 

Plant-fiber identification is described in TAPPI T8 and TIO. In order to identify synthetic fibers, it usually is necessary to conduct solubihty and physical properties tests in addition to light microscopy observations. Systematic sampling is required to obtain quantitative information on sample composition. Because different types of pulps contain varying numbers of fibers per unit weight, it is necessary to multiply the total number of each kind of fiber by a relative weight factor, thereby the weight percentage that each fiber type contributes to the sample can be deterrnined. 

An example adapted from Verneuil, et al. (Verneuil, V.S., P. Yan, and F. Madron, Banish Bad Plant Data, Chemical Engineeiing Progress, October 1992, 45-51) shows the impact of flow measurement error on misinterpretation of the unit operation. The success in interpreting and ultimately improving unit performance depends upon the uncertainty in the measurements. In Fig. 30-14, the materi balance constraint would indicate that S3 = —7, which is unrealistic. However, accounting for the uncertainties in both Si and S9 shows that the value for S3 is —7 28. Without considering uncertainties in the measurements, analysts might conclude that the flows or model contain bias (systematic) error. 

Model Development PreHminary modeling of the unit should be done during the familiarization stage. Interactions between database uncertainties and parameter estimates and between measurement errors and parameter estimates coiJd lead to erroneous parameter estimates. Attempting to develop parameter estimates when the model is systematically in error will lead to systematic error in the parameter estimates. Systematic errors in models arise from not properly accounting for the fundamentals and for the equipment boundaries. Consequently, the resultant model does not properly represent the unit and is unusable for design, control, and optimization. Cropley (1987) describes the erroneous parameter estimates obtained from a reactor study when the fundamental mechanism was not properly described within the model. 

Single-Module Analysis Consider the single-module unit shown in Fig. 30-10. If the measurements were complete, they would consist of compositions, flows, temperatures, and pressures. These would contain significant random and systematic errors. Consequently, as collected, they do not close the constraints of the unit being studied. The measurements are only estimates of the actual plant operation. If the actual operation were known, the analyst could prepare a scatter diagram comparing the measurements to the actual values, which is a useful analysis tool Figure 30-19 is an example. 

Both common and systematic names of compounds are used throughout this volume, depending on which the Editor-in-Chief feels is most appropriate. Preparations appear in the alphabetical order of names of the compound or names of the synthetic procedures. The Chemical Abstracts indexing name for each title compound, if it differs from the title name, is given as a subtitle. Because of the major shift to new systematic nomenclature adopted by Chemical Abstracts in 1972, many common names used in the text are immediately followed by the bracketed, new names. Whenever two names are concurrently in use, the carre CChemical Abstracts name is adopted. The prefix n- is deleted from -alkanes and w-alkyls. All reported dimensions are now expressed in S st me International units. 

The successive crops of crystals are systematically recrystallized as follows, using Norite if necessary. About two-thirds of the first crop is dissolved in about three parts of water and the hot solution allowed to deposit crystals by slow cooling (Note 3). The liquor is filtered or decanted, the remainder of the first crop is dissolved in it, and the process of crystallization is repeated. The remaining crops are then similarly recrystallized in succession from the same liquor, the solution being evaporated to the appropriate volume before each crystallization. The final mother liquor is evaporated in stages and the viscous residue is united with that from the original crystallization. The various crops are systematically recrystallized from fresh water until pure... 

As with other major plastics materials, there is at present little use of the lUPAC systematic nomenclature, which is based on the nature of the repeating unit rather than the monomer used. The following names may, however, be noted ... 

The emission yield, Ra, defined as the radiation of the spectral line, k, of an element, i, emitted per unit sputtered mass must be determined independently for each spectral line. The quantities g, and Ry are derived from a variety of different standard bulk samples with different sputtering rates. In practice, both sputtering rates and excitation probability are influenced by the working conditions of the discharge. Systematic variation of the discharge voltage, L/g, and current, I, leads to the empirical intensity expression [4.185] ... 

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