diff --git a/component_failure_modes_definition/paper.tex b/component_failure_modes_definition/paper.tex index 4d20f40..1e593b9 100644 --- a/component_failure_modes_definition/paper.tex +++ b/component_failure_modes_definition/paper.tex @@ -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} diff --git a/symptom_ex_process/algorithm.tex b/symptom_ex_process/algorithm.tex index b237572..281747f 100644 --- a/symptom_ex_process/algorithm.tex +++ b/symptom_ex_process/algorithm.tex @@ -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. diff --git a/symptom_ex_process/introduction.tex b/symptom_ex_process/introduction.tex index b59f35a..c9ec4de 100644 --- a/symptom_ex_process/introduction.tex +++ b/symptom_ex_process/introduction.tex @@ -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. diff --git a/symptom_ex_process/process.tex b/symptom_ex_process/process.tex index 82b6b4b..7583660 100644 --- a/symptom_ex_process/process.tex +++ b/symptom_ex_process/process.tex @@ -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. diff --git a/symptom_ex_process/topbot.tex b/symptom_ex_process/topbot.tex index c4b141d..dd27a39 100644 --- a/symptom_ex_process/topbot.tex +++ b/symptom_ex_process/topbot.tex @@ -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 diff --git a/thesis.tex b/thesis.tex index afc12e1..f2d0605 100644 --- a/thesis.tex +++ b/thesis.tex @@ -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}