Mean time to failure (MTTF ) is one of the most frequently used dependability measures in practice. By convention, MTTF is the expected time for a system to reach any one of the failure states. For some systems however, the mean time to absorb to a subset of the failure states is of interest. Therefore, the concept of conditional MTTF may well be useful. In this paper, we formalize the de nitio...

A widely accepted equation for availability is Availability=MTTF/(MTTF+MTTR), where MTTF is the mean time to failure of a system or subsystem (i.e. the reciprocal of reliability), MTTR is its mean time to recovery, and A is a number between 0 and 1. The equation suggests that to improve availability, a 10x decrease in MTTR (for example) is just as valuable as a 10x increase in MTTF, a founding ...

How do you calculate the MTTF (Mean Time To Failure) when you have zero failures? If you use the standard equation for MTTF, which is the ratio of total testing time and the number of failures, you get an answer of infinity. In such cases, you define a confidence level between 0 and 100 and then compute the lower bound chi-square value using two degrees of freedom. The equation for calculating ...

When P2P systems are used for data sensitive systems, the data availability has become an important issue. The availabilitybased replication using individual node availability is the most popular method keeping high data availability efficiently. However, since the individual node availability is derived by the individual lifetime information of each node, the availability-based replication may...

This paper presents the reliability and mean time to failure estimation of a deteriorating system that deteriorates with time. The system is two unit active parallel system where the units operates simultaneously. In this study maintenance is not allowed to the system. Laplace transforms is being utilize to solve the mathematical model developed. Expressions for reliability and Mean time to fai...

Two, ASENs and ZTNs, fault-tolerant multistage interconnection networks of different class are compared, based on their analytic bounds of MTTF, cost, and cost-effectiveness. The full-access condition and deadfault model are used for the MTTF analysis. The simulation study reveals that ZTNs are better in terms of cost and cost-effectiveness while both networks are equally reliable in terms of u...

All genomes require a system for avoidance or handling of collisions between the machineries of DNA replication and transcription. We have investigated the roles in this process of the mTERF (mitochondrial transcription termination factor) family members mTTF and mTerf5 in Drosophila melanogaster. The two mTTF binding sites in Drosophila mtDNA, which also bind mTerf5, were found to coincide wit...

This paper describes theoretical reliability analysis of a system containing n optical ports in which each port contains m redundant vertical-cavity surface-emitting lasers. We study the wearout failure statistics, modelled with lognormal distribution, for three different chip-level integration approaches: (A) laser on its own chip, resulting m·n chips, (B) lasers associated one channel are sin...

Abstract The average lifetime or the mean time to failure (MTTF) of a product is an important metric measure reliability. Current methods evaluating MTTF are mainly based on statistics data. They need testing number products get samples, which then used estimate MTTF. testing, however, expensive in terms both and cost. efficiency also low because it cannot be effectively incorporated early desi...

The 2 out of 4-system (2oo4) is an advanced safety architecture. A 2oo4-system is 2-failure safe, this means that at least two of the four channels have to work correctly in order to trigger the safety function. In order to classify the quality of a system different parameters have to be calculated, like the PFD and MTTF. In this paper, equations are indicated for PFD for normal and common-caus...