Qualitative methods

Goldshtein R., Entov V. (1989) Qualitative methods in continuum mechanics. Nauka, Moscow (in Russian). 

We previously encountered failure modes and effects (FMEA) and failure modes effects and criticality analysis (FMECA) as qualitative methods for accident analysis. These tabular methods for reliability analysis may be made quantitative by associating failure rates with the parts in a systems model to estimate the system reliability. FMEA/FMECA may be applied in design or operational phases (ANSI/IEEE Std 352-1975, MIL-STD-1543 and MIL-STD-1629A). Typical headings in the F.Mld. A identify the system and component under analysis, failure modes, the ef fect i>f failure, an estimale of how critical apart is, the estimated probability of the failure, mitigaturs and IHissihiy die support systems. The style and contents of a FMEA are flexible and depend upon the. ilitcLiives of the analyst. 

Evaluation can be performed by measuring capture efficiency using real contaminants and applying the real process or by substituting with tracer materials. A simpler, but qualitative, method of evaluation is the visualization of the airflow. If the relationship between capture efficiency and airflow rate is known, a measurement of the airflow rate can be used for frequent evaluation. See Section 10.5. 

Given these uncertainties, it becomes even more important that a systematic and comprehensive qualitative method is adopted for identifying the sources of risk and the consequences of failures. Such a procedure must ensure... 

It is important to recognize that the following analytical methods essentially determine EO-PO ratio ( H NMR, IR, cleavage methods) or even simply alkylene oxide content (compleximetric methods) of the analyte, and as such are not specific quantitative or qualitative methods for poloxamers, since EO-PO copolymers of a different structure (for instance, random copolymers, or PO-EO-PO block copolymers) may respond to the methods in a way indistinguishable from poloxamers. The principal technique that permits definitive identification of a sample as a poloxamer is C NMR, which allows structural details, such as the distribution of EO and PO units along the polymer chain, to be elucidated [10]. 

Bromine number (ASTM D-1159) and bromine index (ASTM D-2710) are qualitative methods to measure the reactive sites of a sample. Bromine reacts not only with olefm bonds, but also with basic nitrogen molecules and with some aromatic sulfur derivatives. Neverthele.ss. olefins are the most common reactive sites and the bromine number is used to indicate olefinicity of the feed. 

As one dilutes the amount of an element in an arc, the number of lines observable is reduced, and ultimately there remain only a few lines of the element which is diluted. These lines are referred to in Section 20.2 as the raies ultimes or persistent lines and tables of their wavelengths may be found in chemical handbooks. The identification of these lines will permit detection of elements present in low concentration, and all qualitative methods utilise the persistent lines. 

Everything we have mentioned so far has been the qualitative method for comparing acidity of different protons. In other words, we never said how much more acidic one proton is over another, and we never said exactly how acidic each proton is. We have talked only about relative acidities which proton is more acidic ... 

The calculation of standard deviation may be based on single or duphcate determinations qualitative methods need other criteria, which are given... 

Carrying out a number of co-oxidation experiments with various hydrocarbon mixtures, one compares the results of experiment with that of computer simulations and step by step estimates of the parameters rl5 r2, Sl5 S2, and (/>. This technique is an effective qualitative method for estimating these coefficients. This technique is described in monographs and papers [5-9],... 

The QRA method is designed to provide managers with a tool to help them evaluate the overall risk of a process. QRAs are used to evaluate potential risks when qualitative methods cannot provide an adequate understanding of the risks. QRA is especially effective for evaluating alternative risk reduction strategies. 

In general, risk reduction is accomplished by implementing one or more protective layers, which reduce the frequency and/or consequence of the hazard scenario. LOPA provides specific criteria and restrictions for the evaluation of protection layers, eliminating the subjectivity of qualitative methods at substantially less cost than fully quantitative techniques. LOPA is a rational, defensible methodology that allows a rapid, cost-effective means for identifying the protection layers that lower the frequency and/or the consequence of specific hazard scenarios. 

Patton M.Q., 1987. How to use qualitative methods in evaluation, Sage publishing, Newbury Park. 

Infrared analysis is usually used as a qualitative method to identify substances. Liquids are usually analyzed as pure substances in cells with very small optical path lengths of 0.1-1.0 mm. Usable spectra can be obtained by placing a drop of relatively non-volatile sample between two sodium chloride plates, allowing them to be held together by capillary action. 

A qualitative method enables only the presence of the substance to be detected. 

The reactions of the carbonyl group form the basis of many qualitative methods for the detection of carbohydrates and several have been used quantitatively. These are general methods that often only measure the total amount present in the sample. However, in some cases, reagents or reaction conditions have been modified to improve specificity. 

Selected applications of small-scale preparative l.c. of carbohydrates are given in Table IV. Although the amounts of carbohydrate isolated are low (several pig to 20 mg), they are often enough for subsequent qualitative methods such as H-n.m.r. spectroscopy. By computer automa-... 

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