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The bathtub curve is a particular shape of a failure rate graph. This graph is used in reliability engineering and deterioration modeling. The 'bathtub' refers to the shape of a line that curves up at both ends, similar in shape to a bathtub. The bathtub curve has 3 regions: The first region has a decreasing failure rate due to early failures.
A well-known model to show the probability of failure of an asset throughout its life is called bathtub curve. This curve is made of three main stages: infant failure, constant failure, and wear out failure. In infrastructure asset management the dominant mode of deterioration is because of aging, traffic, and climatic attribute.
However, this is only valid if the failure rate () is actually constant over time, such as within the flat region of the bathtub curve. In many cases where MTBF is quoted, it refers only to this region; thus it cannot be used to give an accurate calculation of the average lifetime of a system, as it ignores the "burn-in" and "wear-out" regions.
An example is the bathtub curve hazard function, which is large for small values of , decreasing to some minimum, and thereafter increasing again; this can model the property of some mechanical systems to either fail soon after operation, or much later, as the system ages.
The occurrence of infant mortality in a population can be described by the infant mortality rate (IMR), which is the number of deaths of infants under one year of age per 1,000 live births. [1] Similarly, the child mortality rate , also known as the under-five mortality rate, compares the death rate of children up to the age of five.
The Fogg Behavior Model (FBM) [12] is a design behavior change model introduced by BJ Fogg. This model posits that behavior is composed of three different factors: motivation, ability and a prompt. Under the FBM, for any person (user) to succeed at behavior change needs to be motivated, have the ability to perform the behavior and needs a ...
Examples are maximum one-day rainfalls and the time a user spends on a web page. The distribution is named after Swedish mathematician Waloddi Weibull , who described it in detail in 1939, [ 1 ] [ 2 ] although it was first identified by René Maurice Fréchet and first applied by Rosin & Rammler (1933) to describe a particle size distribution .
Child mortality is the death of children under the age of five. [2] The child mortality rate (also under-five mortality rate) refers to the probability of dying between birth and exactly five years of age expressed per 1,000 live births. [3] It encompasses neonatal mortality and infant mortality (the probability of death in the first year of ...