Human reliability curve

Such a task description invites task analysis, which would lead naturally to human reliability analysis (HRA). Indeed, perhaps the earliest work in this field applied HRA techniques to construct fault trees for aircraft structural inspection (Lock and Strutt 1985). The HRA tradition lists task steps, such as expanded versions of the generic functions above, lists possible errors for each step, then compiles performance shaping factors for each error. Such an approach was tried early in the FAA s human factors initiative (Drury et al. 1990) but was ultimately seen as difficult to use because of the sheer number of possible errors and PSFs. It is occasionally revised, such as in the current FRANCIE project (Haney 1999), using a much expanded framework that incorporates inspection as one of a number of possible maintenance tasks. Other attempts have been made to apply some of the richer human error models (e.g.. Reason 1990 Hollnagel 1997 Rouse 1985) to inspection activities (La-toreUa and Drury 1992 Prabhu and Drury 1992 Latorella and Prabhu 2000) to inspection tasks. These have given a broader understanding of the possible errors but have not helped better define the PoD curve needed to ensure continuing airworthiness of the civil air fleet. 

Figures from 7 to 12 give the curves of probability evaluation for the 6 experimental data. From the curves, the differences are small among the different groups and conditions. The results of parameters identification are concentrative, and then can be used as the base for human reliability evaluation.

This study demonstrates high efficacy and expediency of the TCNQ derivative-based point-contact multistracture as a prospective asset for development of new sensors. The complex character of the sensors response curve and correlation of some response characteristics with different pathological manifestations in human breath, may be further used as a noninvasive diagnostic method alternative to some invasive approaches currently routinely used in clinic. The need for reliable and feasible gas analysis methods functional in presence of atmospheric air, opens opportunities for application of the proposed sensor technique in other spheres of human activity. High sensitivity of the point-contact multistructure enabling analysis of composite gas mixtures, opens up wide possibilities to apply the demonstrated approach for environment and health protection, such as detection of trace amounts... 

Semi-automatic features. Facilities such as autozero, automatic linearization of the calibration curve, digital readout in concentration units, and a printer are all highly desirable, and jointly they greatly improve the cost-effectiveness of analysis, because the cost of the operator and the instrument can be distributed among a disproportionately larger number of samples. However, it has yet to be demonstrated that, over a long period, an automatic sample introduction system is as quick or reliable as a motivated human operator in flame AAS. Fully automatic systems are rarely... 

Potency estimates derived from such animal studies help to characterize the dose-response relationship at the low-exposure levels to which humans are likely to be exposed and to predict the quantitative estimate of the risks that humans are likely to encounter at ambient exposures. Experimental evidence for various shapes of the dose-response curve for carcinogens showed that reliable high-dose data from human studies contain examples of superlinearity, linearity, and sublinearity. These are also seen in animal studies. But there are no data to indicate the shape of the dose-response relationship corresponding to lifetime risk of one in a million, the insignificant risk level generally used by the regulatory agencies. 

If the statistical fluctuations discussed above, the human factor introduced by the technician doing the work, as well as the differences in presentation and interpretation of data by various test methods are all taken into consideration, it seems extremely difficult to obtain reliable and reproducible results. This conjecture was proved some time ago with a very interesting, but also very shocking, diagram. Figure 23.1 shows twenty-one (21) particle size distribution curves in a probability log diagram. The cumulative percent undersize is plotted versus the measured particle size in micrometers. 

The predicted risk to humans based on these types of studies is completely dependent upon the underlying assumptions used to make the prediction. If we only have the high-dose data, and even if we determine in laboratory animal studies that there is a dose-response curve and a threshold exists, we often must use a straight-line (linear) approach from this high-dose data since it is the only reliable and legally accepted data we have. However, other models are possible if more data are available and certain assumptions are made. Whatever we do, we are essentially guessing since no human data is collected at these lower doses. This process is depicted in Figure 2.2. 

Hemolysis data are known to provide a simple and reliable measure for the estimation of CyD-induced membrane damage or cytotoxicity [10, 14). Figure 14.2 shows the hemolysis curves of hydrophilic CyDs on rabbit erythrocytes. The hemolytic effects of methylated CyDs are much higher than those of other CyDs [32, 33). In a series of CyD derivatives, there is a positive correlation between the hemolytic activity and their capacity to solubilize the lipophilic components of the cell membranes (cholesterol and phospholipids). Since the methylated CyDs remove cholesterol significantly from human intestinal epithelial cell monolayers [34], this will... 

The FN-curve due to flooding on a national scale of Vietnam are in Fig. 1 (Mai Van et al. 2008). It is noted that these curves were estabUshed on the basis of historical loss information in terms of economic damages and human lives due to all-cause-flood events of Vietnam in the last century. The most important and reliable source of information used in these analysis is the top 25 flood disasters of Vietnam in the 20th century, which currently available in the report of Asian Disaster Reduction Centre (ADRC, 2006). 

Statistical values can also be used to determine expected periods of optimum performance in the life cycle of products, systems, hardware, or equipment. For example, if the life cycle of humans were plotted on a curve, the period of their lives that may be considered most useful, in terms of productivity and success, could be represented as shown in Figure 5.4. This plotted curve is often referred to as the bathtub curve because of its obvious shape. A similar curve can be used to determine the most productive period of a product s life cycle according to the five known phases of that life cycle, as discussed in Chapter 3. The resultant curve, known as a product s reliability curvey would resemble the curve that appears in Figure 5.5. During the breakin period, failures in the system may occur more frequently, but decreasingly less frequently as the curve begins to level toward the useful life period. Then, as the system reaches the end of its useful life and approaches wearout, more frequent failure experience is likely until disposal. 

Methane gas served as both the gas chromatographic carrier gas and the reagent gas in the chemical ionization source (at 1000 y pressure). The mass spectrometer was operated in the selected ion recording mode, and the quasimolecular ions of PF and Ara-Virazole were monitored at m/e 692 and m/e 517, respectively two fragment ions (loss of methyl group) were also monitored. A calibration curve was established using known amounts of PF added to pooled human serum. The observed areas of PF and the internal standard were used to calculate area ratios which, in turn, were used to determine the amount of PF in serum. Using this method minimum detectable quantity is 10 ng/ml serum lowest level at which quantification is still reliable is 100 ng/ml serum. 

---