Failure targets

Treatment of acute heart failure targets relief of congestion and optimization of cardiac output utilizing oral or intravenous diuretics, intravenous vasodilators, and when appropriate, inotropes. 

Figure 1.56 Schematic view of relationships among hypothetical times-to-failure, targets for design life (DLO, DLCO, LEO, and LECO) action levels (AL 1, AL 2, AL 3, AL 4, and AL 5) and responses appropriate for each action level. Black dots indicate high priority actions, shaded dots indicate lower priority actions open circles indicate no action...

Heart failure, targeting 1284 Heat shock proteins... 

The failure target or goal-based approach (Kritzinger (2006), Chapter 6) found in standards such as FAR25.1309. 

Operation of FBTR at 10.5 MWt is continued The maximum fiml burnup reached is 32,000 MWd/t without any failure. Targeted bumup is 50,000 MWd/t. Post irradiation examination has been completed on one fuel subassembly taken out at 25,000 MWd/t. The performance of the fuel is very good Turbine was rolled upto synchronous speed of 3000 rpm several times during the year and operation was found to be smooth. TG synchronisation with grid will be achieved during the reactor operation at 12.5 MWt, with the addition of fuel subassemblies in the core. 

Statistical data available at 70% confidence to verify random hardware failures target ... 

ASIL Random hardware failure target values... 

In practice, most of the ground-based ATC barriers are implemented by the same controllers and equipment items so the barriers are not independent, and methods such as Fault Tree Analysis (FTA) are needed to apportion both success and failure targets to individual subsystems within the overall ATM system. 

Tests using a constant stress (constant load) normally by direct tension have been described in ISO 6252 (262). This test takes the specimen to failure, or a minimum time without failure, and frequently has a flaw (drilled hole or notch) to act as a stress concentrator to target the area of failure. This type of testing, as well as the constant strain techniques, requires careful control of specimen preparation and test conditions to achieve consistent results (263,264). 

Should any discrete device not remain in its target state, failure logic must be initiated. 

Local Failure The penetration or perforation of most industrial targets cannot be assessed using theoretical analysis methods, and recourse is made to using one of the many empirical equations. In using the equations, it is essential that the parameters of the empirical equation embrace the conditions of the actual fragment. 

Modern equipment is frequently eomposed of thousands of eomponents, all of whieh interaet within various toleranees. Failures often arise from a eombination of drift eonditions rather than the failure of a speeifie eomponent (Smith, 1993). For example, typieally an assembly toleranee exists only to limit the degradation of the assembly performanee. Being off target may involve later warranty eosts beeause the produet is more likely to break down than one whieh has a performanee eloser to the target value (Vasseur et al., 1992). This again is related to manufaeturing variation problems, and is more diffieult to prediet, and therefore less likely to be foreseen by the designer (Smith, 1993). 

The analysis indicated that the conformance problems associated with the hub design had a cost of failure of more than 30%. This would represent at the annual production quantity required and target selling price, a loss to the business of several million pounds. As a result of the study the business had further detailed discussions with their suppliers and not surprisingly it turned out that the supplier would only be prepared to stand by its original quotation provided the tolerances on the hub, discussed above, were opened up considerably (more than 50%). Subsequently, this result supported the adoption of another more capable design scheme. 

We now have a means of predieting the standard deviation multiplier z whieh ean be used in equation 3.2. However, z, the assembly toleranee standard deviation multiplier, must be estimated before this equation ean be satisfied. This is aehieved by setting a eapability requirement. The level of eapability required typieally by industry is Cp = 2 (Harry and Stewart, 1988 O Connor, 1991) whieh equates to 0.002 parts-per-million (ppm) (see Appendix II for a relationship between Cp, Cp and ppm). Note, this value is with no failure severity taken into aeeount, but is a blanket target value diffieult to realize in praetiee. It follows then for the overall assembly proeess eapability for a bilateral assembly toleranee ean be given from equation 3.7 as ... 

Sinee the poorest performanee of the assembly distribution would oeeur when shifted, Cpk values rather than Cp values are better design targets. The Cp value ean be used as a target for the assembly based on the severity of applieation and minimum failure eost of 0.01% of the total produet eost as determined by the Conformability Map. If only eapable solutions are to be generated, whieh have a minimum proeess eapability index of Cp =1.33 (or 30 ppm) for both eomponent and assembly distributions, then the number of eomponents in the assembly staek ean be as low as three using the proposed statistieal model (Harry and Stewart, 1988). The overall requirement is... 

Reliability targets are typically set based on previous product failures or existing design practice (Ditlevsen, 1997) however, from the above arguments, an approach based on FMEA results would be useful in setting reliability targets early in the design process. 

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