Mum proof read of English

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Robin Clark 2010-08-17 21:47:01 +01:00
parent d3ba235571
commit 2b5b46e8cb
6 changed files with 29 additions and 27 deletions

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@ -20,7 +20,7 @@
% numbers at outer edges
\pagenumbering{arabic} % Arabic page numbers hereafter
\author{R.P.Clark}
\title{Definitions, Components, Functional Groups and Unitary State Failure Mode Sets}
\title{Definitions, Components, Functional Groups \\ and Unitary State Failure Mode Sets}
\maketitle
\input{component_failure_modes_definition_paper}

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@ -37,7 +37,7 @@ will have an $\alpha$ value of 1.
%of the highest assigned to any of its components.
%
%With a derived component $DC$ having an abstraction level
The attribute $\alpha$ we can be used to track the
The attribute $\alpha$ can be used to track the
level of fault abstraction of components in an FMMD hierarchy. Because base and derived components
are collected to form functional groups, a hierarchy is
naturally formed with the abstraction levels increasing with each tier.
@ -84,7 +84,7 @@ $$FM(FG) = F$$
\begin{algorithmic}[1]
\REQUIRE {FG is a set of components (a functional~group)}
\STATE { Let $FG$ be a set of components } \COMMENT{ The functional group should be chosen to be minimally sized collections of components that perform a specific function}
\STATE { Let $FG$ be a set of components } \COMMENT{The functional group should be chosen to be minimally sized collections of components that perform a specific function}
\FORALL { $c \in FG $ }
\REQUIRE{ Each component $c \in FG $ has a known set of failure modes i.e. $ \forall c \in FG \; such \; that\; FM(c) \neq \emptyset$ }
@ -171,7 +171,7 @@ $$ DTC(F) = TC $$
\COMMENT { This corresponds to checking that each possible double failure mode is considered
as a test case; more rigorous cardinality constraint
checks may be required for some safety standards. Note if both failure modes
in the check are sourced from the same component $c$ the test case is impossible
in the check are sourced from the same component $c$, the test case is impossible
under unitary state failure mode conditions}
\ENDIF
@ -240,7 +240,7 @@ the test case failure modes will cause.
%
In the case of a simple
electronic circuit, we could calculate the effect on voltages
within the circuit given certain component failure modes for instance.
within the circuit given certain component failure modes, for instance.
The affect of these unusual volatges would then be a failure
mode of the functional group and become the result of the test case.
When each test case has been analysed, we have a set of
@ -334,7 +334,7 @@ component created in the next stage.
}
{
Note ensuring that no result belongs to more than one symptom
set enforces unitary state failure mode constraint for derived components.
set enforces the `unitary state failure mode constraint' for derived components.
}
%% Interesting to draw a graph here.
@ -440,7 +440,7 @@ Because the fault modes are determined from the bottom-up, the causes
for all high level faults naturally form trees.
These trees can be traversed to produce
minimal cut sets\cite{nasafta} or entire FTA trees\cite{nucfta}, and by
analysing the statistical likelyhood of the component failures,
analysing the statistical likelihood of the component failures,
the MTTF and SIL\cite{en61508} levels can be automatically calculated.

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@ -1,20 +1,20 @@
{
\section{Introduction}
This chapter describes a process for taking a functional group of components,
applying FMEA analysis on all the component failure modes possible in that functional~group,
and then determining how that functional group can fail.
This chapter describes a process for taking a {\fg} of components,
applying FMEA analysis on all the component failure modes possible in that {\fg},
and then determining how that {\fg} can fail.
%
%
With this information, we can treat the functional group
With this information, we can treat the {\fg}
as a component in its own right.
This new component is a derived from the functional~group.
In the field of safety engineering this derived component correspond to a low~level sub-system.
This new component, is a derived from the {\fg}.
In the field of safety engineering this derived component corresponds to a low~level sub-system.
%The technique uses a graphical notation, based on Euler\cite{eulerviz} and Constraint diagrams\cite{constraint} to model failure modes and failure mode common symptom collection. The technique is designed for making building blocks for a hierarchical fault model.
%
Once the failure modes have been determined for a sub-system/derived~component,
this derived component can be combined with others to form functional groups
Once the failure modes have been determined for a sub-system/{\dc},
this {\dc} can be combined with others to form {\fgs} groups
to model
higher level sub-systems/derived~components.
higher level sub-systems/{\dcs}.
%
In this way a hierarchy to represent the fault behaviour
of a system can be built from the bottom~up. This process can continue
@ -24,7 +24,7 @@ behaviour of the entire system under analysis.
Using the FMMD technique the hierarchy is built from the bottom up to ensure complete failure mode coverage.
Because the process is bottom-up, syntax checking and tracking can ensure that
no component failure mode can be overlooked.
Once a hierarchy is in place it can be converted into a fault data model.
Once a hierarchy is in place, it can be converted into a fault data model.
%
From the fault data model, automatic generation
of FTA\cite{nasafta} (Fault Tree Analysis) and mimimal cuts sets\cite{nucfta} are possible.

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@ -52,7 +52,9 @@ It is possible here for an automated system to flag unhandled failure modes.
\ref{requirement at the start}
\section{The Process : To analyse a base level Derived~Component/sub-system}
\section{The Process}
\paragraph{To analyse a base level Derived~Component/sub-system}
To sumarise:
@ -73,7 +75,7 @@ form `test cases'.
\clearpage
\pagebreak[1]
\section{A theoretical `Derived Component' example}
Consider a functional group $FG$ with components $C_1$, $C_2$ and $C_3$.
@ -270,9 +272,9 @@ Where DC is a derived component, and FG is a functional group:
% \caption{Deriving a new diagram}
This sub-system or derived~component $DC$ , with its three error modes, can now be treated as a component (although at a higher level of abstraction)
This sub-system or {\dc} $DC$, with its three error modes, can now be treated as a component (although at a higher level of abstraction)
with known failure modes.
This process can be repeated using derived~components to build a
This process can be repeated using {\dcs} to build a
hierarchical fault~mode model.

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@ -4,7 +4,7 @@
\subsection{Static Analysis}
In the field of safety critical engineering; to comply with
European Law a product must be certified under the approriate `EN' standard.
European Law a product must be certified under the appropriate `EN' standard.
Typically environmental stress, EMC, electrical stressing, endurance tests,
software~inspections and project~management quality reviews are applied\cite{sccs}.
@ -14,7 +14,7 @@ Three main techniques are currently used,
Statistical failure models, FMEA (Failure mode Effects Analysis) and FTA (Fault Tree Analysis).
The FMMD technique is a static modelling methodology, aimed primarily as design verification for
safety critical systems.
However, FMMD also provides the mathematical frame work
However, FMMD also provides the mathematical framework
to assist in the production of the three traditional methods of static analysis.
From the model created by the FMMD technique, statistical, FTA and FMEA models
can be derived.
@ -133,10 +133,10 @@ component failure modes.
Using the reasoning that working from the bottom up forces the consideration of all possible
component failures (which can be missed in a top~down approach)
we are presented with a problem. Which initial collections of base components should we choose ?
we are presented with a problem. Which initial collections of base components should we choose?
For instance in the CD~player example; to start at the bottom; we are presented with
a massive list of base~components, resistors, motors, user~switches, laser~diodes, all sorts !
a massive list of base~components, resistors, motors, user~switches, laser~diodes, all sorts!
Clearly, working from the bottom~up, we need to pick small
collections of components that work together in some way.
These are termed `functional~groups'. For instance the circuitry that powers the laser diode

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@ -58,7 +58,7 @@
\chapter{Safety Critical systems Analysis}
\input{statistics/statistics}
\chapter{Survey of Safety Critical Analysis Methodologies and Tools Available}
\chapter{Survey of Safety Critical \\ Analysis Methodologies \\ and Tools Available}
\input{survey/survey}
@ -66,7 +66,7 @@
\input{standards/standards}
\typeout{ ---------------- Component Failure Modes Definition }
\chapter { Component Failure Modes Definition}
\chapter { Component Failure \\ Modes Definition}
\input{component_failure_modes_definition/component_failure_modes_definition}