Data assessment

Data have been obtained from two prime sources - published literature and the material suppliers. 

Published literature has been primarily accessed via RAPRA s bibliographic base using a suitable search strategy. This has been supplemented from other sources including references cited in the original source documents. Where possible, additional information has been sought directly from the material suppliers. 

The time frame is primarily from 1985 onwards for the following reasons  

Materials suppliers have a vast amount of information, mainly unpublished, which has been accumulated in characterizing their own products singly and in combination with other resins or reinforcements. 

This information has been used selectively to infill gaps that appear in the literature and to provide the basis for inter-comparison with other data. The assessment strategy is listed in Table 2.10. 

particularly normalized data, is evaluated to determine the nature of the loss in membrane performance (see Chapter 11.3 for a complete discussion on data normalization). Normalized permeate flow, salt rejection, and differential pressure should be evaluated to determine trends in performance. 

As discussed in Chapter 13.2, normalized data should be used to determine when the membranes should be cleaned. Normalized data should be scanned to determine if the membranes were cleaned on time, or if potential fouling and/or scaling could become permanent because the membranes were not cleaned on time. 

Case Normalized Permeate Flow Normalized Salt Passage Normalized Differential Pressure Location Probable Causes 

3 Up Greatly up Stable Random O-ring, membrane failure 

6 Greatly down Stable Stable All stages Organic fouling 

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Appendix III contains failure rate estimates for various genetic types of mechanical and electrical equipment. Included ate listings of failure rates with range estimates for specified component failure modes, demand probabilities, and times to maintain repair. It also contains some discussion on such special topics as human errors, aircraft crash probabilities, loss of electric power, and pipe breaks. Appendix III contains a great deal of general information of use to analysts on the methodology of data assessment for PRA. 

WASH-1400 is a fundamental document for PRA methodology. The data appendixes contain a great deal of useful information on methods of data assessment. A large number of sources for data are considered, and very general failure rate estimates will produce only gross approximations. Since the advent of data collection schemes across and within plants, the WASH-1400 data are solely useful as a constituent to a data aggregation process or as widely bounded figures that provide a basis for comparison. 

Hoemke, P. Experience in Germany with Reliability Data Assessment, Results and Current Problems. Paper II.B.2, ANS/ENS Topical Meeting on PRA, September, 1981. 

Combustion controls such as oxygen trim help to maintain optimum operating conditions, especially on gaseous fuels. Instrumentation can give continuous visual and recorded information of selected boiler and plant functions. To be effective, it must be maintained and the data assessed and any required action taken before the information is stored. 

Technical resources are readily available to identify chemical reactivity hazards, acquire needed data, assess risks, and develop safeguards. 

ESCIS 1993. Thermal Process Safety Data, Assessment Criteria, Measures. Safety Series, Booklet 8. Basel, Switzerland Expert Commission for Safety in the Swiss Chemical Industry. April. Order online at www.escis.ch/seiten/englrsh/ publication.htm. 

NRTL-SAC has been demonstrated through the case study on Cimetidine as a valuable aid to solubility data assessment and targeted solvent selection for crystallization process design. The average model error is typically 0.5 Ln (x) [1] and is sufficient as a solvent screening tool. Methods that can deliver greater accuracy would increase the value and utility of these techniques. It is impressive in the case of Cimetidine that the NRTL-SAC correlation is capable of reasonable accuracy and predictive capability on the basis of just 2 fitted parameters. Further work to extend the solvent database and optimize the descriptive parameters will be beneficial, and are planned by the developers. 

When can a set of data be regarded as a database Guidelines such as the number of records or the publication medium may not be useful. CODATA values, for example, which are the recommended starting point for any database (or any thermochemical calculation, for that matter), involve only about 150 species. Also, the CODATA reports have been printed in regular scientific journals before the final set was released as a book and later posted on the Internet. Second, we could have distinguished between databases and data compilations. The former involve recalculation of quantities such as standard enthalpies of formation to ensure a consistent set of values (see section 2.5). Databases may also include data assessment, leading to recommended values. Data compilations, on the other hand, are just collections of literature values. Although this distinction is important (see table Bl), a data compilation can be rather useful for the expert user and save many hours of literature search. 

Johnson BM, Charman WN, Porter CJH (2003) Application of compartmental modelling to an examination of in vitro intestinal permeability data Assessing the impact of tissue uptake, P-glycoprotein, and CYP3A. Drug Metab Dispos 31 1151-1160. 

The determination of hydrocarbon contaminants in soil is one of the most frequently performed analyses in the study of contaminated sites and is also one of the least standardized. Given the wide variety of hydrocarbon contaminants that can potentially enter and exist in the soil environment, a need exists for methods that quantify these chemicals satisfactorily. Formerly, the idea of total hydrocarbon determination in soil was seen as providing a satisfactory tool for assessing contaminated sites, but the nature of the method and the site specificity dictate a risk-based approach in data assessment. Quantitation of particular hydrocarbon species may be required. 

It is obvious that such an assessment is formidable, technically difficult, and extremely expensive. Since an environmental source assessment study is required to characterize the total pollution potential of all waste streams, the sampling program must be more extensive than those conducted for the acquisition of process or control engineering data. Assessment sampling is more complete in that all waste streams are sampled and no attempt is made to limit sampling to a preselected number of process streams. The sampling is also more comprehensive in that all substances of potential environmental concern must be detectable above some minimum level of concern. These requiements of completeness and comprehensiveness call for a strategy of approach in which the philosophy and structure ensure maximum utilization of available resources. 

Gygax, R. (1993) Thermal Process Safety, Data Assessment, Criteria, Measures,... 

To further characterize the mobility of the IRE loop, time-resolved isotropic fluorescence emission decay components of the IRE RNAs were determined as a function of temperature. Some details of the measurements and data assessment will be necessary here to appreciate both the utility of the information and caveats about its literal interpretation. Considering first the TCSPC instrument itself, some uncertainty in the measurements arise from its intrinsic parameters. With 300 nm incident light, the IRF of the photomultiplier tube ranged from 190 to 276 ps full-width at half-height (FWHH). The width of the IRF and the time resolution (32.5 ps/channel) limit the short components that can be reliably extracted from the fit, and certainly those <200 ps will have large errors on their amplitudes and lifetimes. Fluorescence emission decay components as short as 9—20 ps (Larsen et al., 2001) and 30—70 ps (Guest el al., 1991) (and much shorter by Wan et al., 2000) have been measured for 2AP in a stacked conformation, but in our instrument, a fit to such a short lifetime would be inaccurate. 

Data are most appropriate to use when there is a close match between the needs of the assessment and the characteristics, methods and assumptions underlying the data. Assessment of appropriateness is an important first step towards ensuring accuracy of the data, the second of the hallmarks we discuss (see next section). At worst, when data are completely inappropriate, they should not be used. However, in cases when the match is not as close as desired, clear documentation at least allows for an appraisal of the potential bias and/or uncertainty introduced by utilization of the data. 

In this programme, co-producers of chemicals work together to share health, environmental and safety data, assess chemicals, and engage in a peer review of their assessments with government experts of OECD member countries and NGOs. 

Proposals of compounds for which MRLs are elaborated or proposals for the revision of existing MRLs are considered initially by the CCRVDF and then subsequently submitted to the Codex Commission for approval as new work. The scientific data assessments for these compounds are undertaken by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). 

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