a) How can a system’s reliability be predicted prior to manufacture? 

b) On a sketch of failure rate against time, show how the failure rate is affected when a system is replaced by a dual active redundant solution. 

c) On a sketch of failure rate against time show the effect that environment stress screening would have on failure rate. 

d) Give examples of three different environmental stress screening methods and identify the failure mechanisms. 

Comment on the relative advantages of using environmental stress screening over a hardware redundancy method and identify any risk associated with either approach.