Lifetime expectancy

The design engineer would like to be able to predict the life of a component under given conditions on the basis of materials information or short-term tests. He can then choose his material such that the component will outlive its design life, its warranty period, or the lifetime expected by the market. Alternatively, he can set out a plan for maintenance or replacement. This book attempts to explain the methods currently used to make these predictions. 

Design tests during the conception, type tests before the launching of the product, and routine tests after the production are performed by the manufacturers. They are intended to eliminate the component early failures and to provide a high reliability during the given lifetime. The lifetime expectancy estimation presented below concerns the statistical failures of the components considering only the wear out failures. 

An extensive study has been performed to demonstrate a general approach to assess electrochemical capacitor reliability as a function of operating conditions on commercial capacitor cells [75,76], For the temperature dependency an Arrhenius law is used, whereas for the voltage dependency an inverse power law is used. Some electronic apparatus concepts are already available to estimate in situ the DLC residual life by monitoring the temperature and voltage constraints of the application [77], DLC capacitance lifetime expectancies are displayed in Figure 11.16 as a function of the temperature for different values of the applied DC voltage. 

FIGURE 11.16 DLC capacitance lifetime expectation as a function of the temperature for different voltages. The DLC is considered as failed when its capacitance drops below 80% of its nominal value. 

In order to evaluate a material s lifetime expectancy in a short laboratory test the temperature is increased and a temperature-time relationship is developed for some property of the material. Of course, there Is a limit to how high the temperature can be (e.g., 80-90 c for Neoprenes) without Inducing extraneous and unrealistic chemical reactions. More difficult sometimes is the decision criterion when the decay of the... 

Horiuchi S. Demography Greater lifetime expectations. Nature 2000 405 744-745. 

Lifetime expectancy, based on latest experience is one year... 

The increased lifetime expected from reinforcement by particulate fillers naturally refers to cured pieces. The incorporation of reinforcing fillers greatly... 

In the present paper, their application to molecular spectroscopy has been described, with several examples of spectra which could not have been obtained by other means. These results have depended primarily on the tunability and monochromaticity of this radiation. Its directionality has also permitted the use of small gas volumes, and the short duration (of a few nanoseconds) has led to its importance in studies of lifetimes. Expected improvements in intensity, tunability, linewidth, and pulse duration of these laser-driven Sources will further enhance their use in spectroscopy. 

These lifetimes are two orders of magnitude greater than the lifetime expected for a secondary carbocation. The longer lifetimes and the observation of exclusive anti addition support the view that the intermediates are bromo-nium ions and not j8-bromocarbocations. ... 

The model we used to study the interface between OSHA and WC differs from the model developed in Chapter 3 in two respects. First, to increase realism we assumed workers attempt to maximize lifetime expected utility and firms attempt to maximize the present value of long-run expected profits. Second, to study the impact of possible public policy changes we incorporated specific relationships representing OSHA activities and the WC insurance system. 

The problem facing the representative worker is finding the level of risk (n) that maximizes lifetime expected utility subject to it > 0. We represented a worker s expected utility using the strongly separable power utility function... 

Whether or not it is true, I do not like to think of polyurethanes in such terms, simply because these materials can have an excellent durability and lifetime expectancy they are currently used for the most severe applications in industries such as aerospace and military applications. The inherent strength of these materials is vital in the building of other external structures which are subjected to high levels of weight, impact and weathering. 

The problem is complete except for consideration of fatigue effects and of in-use hazards and environmental exposure. The fatigue analysis consists of an examination of the S-N curves for the three materials used, to determine if the lifetime expectancy is adequate for the stress levels used. If there are no S-N data available, the only alternative is a life test on the part or S-N data accumulation for the... 

Mertens B, Weiss M, Meiling H et al (2004) Progress in EUV optics lifetime expectations. Micromech Micromeng 73 16-22... 

The CO-AB optimization process involves three steps (1) determine an AB range for a reformate of certain CO and concentrations (2) measure VDR and ERR at selected AB levels (3) select the optimum AB set point on the basis of VDR/FRR data and cell lifetime expectations. The optimization should consider two additional factors hydrogen safety and anode stoichiometry. The hydrogen safety requirement (Air Prodncts and Chemicals 2004) limits the use of AB to less than 15% as an effective mitigation method for no higher than 200 ppm CO at a Pt-Ru anode. When high AB is nsed, the anode stoichiometry should be adjusted to compensate for the consnmed by the excess to avoid fuel starvation. 

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