Abstract One of the most important reliability parameters is mean time to failure (MTTF). It widely accepted that MTTF equal life E T . This article shows this not necessarily true. Although for commonly used statistical distributions (such as exponential, Gaussian, chi-square, Fisher-Tippett distributions) values and are equal, case log-normal distribution. Similarity, some less Breit-Wigner d...

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...

MTBF (mean time between failures) is the expected time between two successive failures of a system. Therefore, MTBF is a key reliability metric for systems that can be repaired or restored. MTTF (mean time to failure) is the expected time to failure of a system. Non-repairable systems can fail only once. Therefore, for a non-repairable system, MTTF is equivalent to the mean of its failure time ...

In this investigation, the explicit expressions for reliability function and mean time to failure (MTTF) of a repairable system with provision of spares and removable multi-repair facility have been established. In removable repairmen strategy, the repairmen turn on when there are N or more than N failed units and turn-off when system is empty. The failure times of operating/spare units and rep...

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...

Some theoretical evaluation methods of mean time to failure (MTTF) in 2-component standby redundant system with priority have been suggested under the prerequisite that the probability distributions of failure and repair times in each component are respectively specified by the explicit functions. However, this prerequisite might be considerably strict in practical scenes. If we cannot identify...

Un-availability can be quantitatively defined as the ratio of MTTR (mean time to repair) to the sum of MTTR (mean time to repair) and MTTF (mean time to failure). Decreasing MTTR is as valuable as increasing MTTF. By learning why systems fail, failure distribution across parts of an IS, we attempt to envision a plausible model for future Information Technology (IT). In this endeavor, we focus o...

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 ...