



\ifthenelse {\boolean{paper}}
{
\abstract{ 
This paper describes how the Failure Mode Modular De-composition (FMMD) methodology 
can be applied to the problems of common mode failure
analysis.
%
Common mode failures are often difficult to
determine in embedded real time systems.
%
Environmental effects can lead to component failure
modes, that can occur in separate sub-systems
in a system, but interact to create unexpected fault.
% WHAT IS DID
The FMMD methodology can model and warn for two types of common mode failures.
Failures caused by separate sub-systems relying on 
a common component, and environmental effects that can induce failure
modes in components in separate sub-systems.
% WHAT I FOUND
From the FMMD data model it is possible to link the environmental effects
and ensure determine the weak points in a design, where the failure modes may interact.
For the component dependency case, the dependent component 
can be automatically highlighted by traversing the data model.
% WHY YOU WOULD WANT TO READ IT
This feature of FMMD proides another tool in the safety engineers
repotiore, one that can shake out difficult to find common mode failure
effects. 
}
}
{
\paragraph{Chapter overview}
This chapter describes how the % Failure Mode Modular De-composition (FMMD) 
FMMD methodology 
can be applied to the problems of common mode failure
analysis.
%
Common mode failures are often difficult to
determine in embedded real time systems.
%
Environmental effects can lead to component failure
modes, that can occur in separate sub-systems
in a system, but interact to create unexpected fault.
% WHAT IS DID
The FMMD methodology can model and warn for two types of common mode failures.
Failures caused by separate sub-systems relying on 
a common component, and environmental effects that can induce failure
modes in components in separate sub-systems.
% WHAT I FOUND
From the FMMD data model it is possible to link the environmental effects
and ensure determine the weak points in a design, where the failure modes may interact.
For the component dependency case, the dependent component 
can be automatically highlighted by traversing the data model.
% WHY YOU WOULD WANT TO READ IT
This feature of FMMD proides another tool in the safety engineers
repotiore, one that can shake out difficult to find common mode failure
effects. 

}

 
\section{Introduction}

\ifthenelse {\boolean{paper}}
{
paper
}
{
chapter
}


Outline the fmmd process.


Show modules with common dependencies (like on a power supply, a powersupply could have a fault
like nopisy output)


Trace a theoretical example and show how FMMD detects this (common dependency - like two
{\dc}s being depemdent on the same failure mode.


Then show an environmental effect, such as temperature and how 
it can induce faults in sepatate modulkes that
would not be obviously related.

Trace a theoretical example and show how FMMD detects this
i.e. the environmental factor affecting both systems and causing a problem.


what about the third way it can be affected.

Like a chain of relays...... all could get welded .... think about that one.....

