diff --git a/submission_thesis/appendixes/algorithmic.tex b/submission_thesis/appendixes/algorithmic.tex index 0231e6e..fb8590f 100644 --- a/submission_thesis/appendixes/algorithmic.tex +++ b/submission_thesis/appendixes/algorithmic.tex @@ -51,7 +51,7 @@ This process allows us to modularise and thus simplify FMEA analysis of systems. \paragraph{FMEA applied to the {\fg}: choosing test~cases.} As a {\fg} is a collection of components, the failure~modes -that we have to consider are the failure modes of its components. +to consider are the failure modes of its components. %, as %developed in the function definition $fm : \;\mathcal{G} \rightarrow \mathcal{F}$. %The aim here is to build `test cases', @@ -83,7 +83,7 @@ environmental conditions to which it may be exposed. In this way, all possible failure mode behaviour, due to all the conditions that can be applied for all the test~cases will be examined. % \paragraph{Symptom Identification.} -When all test~cases have been analysed, we have a set of FMEA results for the given {\fg}. % applied. +When all test~cases have been analysed, a set of FMEA results exists for the given {\fg}. % applied. These results can be viewed as symptoms of failure of the {\fg}. % %This looks at the results of the `test~cases' as failure modes from the perspective not of the components, but of the {\fg}/sub-system. @@ -115,12 +115,12 @@ These results can be viewed as symptoms of failure of the {\fg}. % We can now create a new component and consider the symptoms as its failure modes. Common symptoms of failure of the {\fg} are collected. % -We can now create a new component to represent the {\fg} and consider these aggregated symptoms as its failure modes. +A new component is created to represent the {\fg} and the aggregated symptoms considered as its failure modes. % -We call this new component a `{\dc}'. +This new component is called a `{\dc}'. % %Note that here, b -Because the FMMD process is bottom up, we can ensure that all failure modes +Because the FMMD process is bottom up, it can be ensured that all failure modes from the components in a {\fg} have been considered. %\footnote{Software can check that all failure modes have been included in at least one test case, and modelled individually. For Double %Simultaneous fault mode checking, all valid double failure modes can be checked for coverage as well.}. @@ -154,7 +154,7 @@ form `test~cases'. % \item Where simultaneous failures are examined use overlapping contours % \item For each region on the diagram, make a test case \item Using the `test cases' as scenarios to examine the effects of component failures, %% APPLY FMEA -we determine the failure~mode behaviour of the {\fg}. + the failure~mode behaviour of the {\fg} is determined. % This is a human process, applying FMEA for each test case. % @@ -192,7 +192,7 @@ that will be used in the algorithmic description of FMMD. Let the set of all possible components be $\mathcal{C}$ and let the set of all possible failure modes be $\mathcal{F}$ and $\mathcal{P}$ the powerset. \fmmdgloss -We can define a function $fm$ which returns the failure modes for a given component (see section~\ref{sec:formal7}): +The function $fm$ is defined which returns the failure modes for a given component (see section~\ref{sec:formal7}): \begin{equation} {fm} : \mathcal{C} \rightarrow \mathcal{P}\mathcal{F} . @@ -201,8 +201,8 @@ We can define a function $fm$ which returns the failure modes for a given compo %defined by (where $C$ is a component and $F$ is a set of failure modes): %$$ fm ( C ) = F $$ -We overload the notation for the function $fm$ -and define it for the set of components within a {\fg} $FG$ (i.e. where $FG \subset \mathcal{C} $) thus: +The notation for the function $fm$ is overloaded +and defined for the set of components within a {\fg} $FG$ (i.e. where $FG \subset \mathcal{C} $) thus: \begin{equation} fm : FG \rightarrow \mathcal{F} . @@ -211,7 +211,7 @@ fm : FG \rightarrow \mathcal{F} . Where $\mathcal{FG}$ is the set of all sets of {\fgs}, and $\mathcal{DC}$ -is the set of all derived components, we can define the symptom abstraction process thus: +is the set of all derived components, the symptom abstraction process is defined thus: $$ %\derivec : SubSystemComponentFaultModes \rightarrow DerivedComponent \derivec : \mathcal{FG} \rightarrow \mathcal{DC} . @@ -327,13 +327,15 @@ all components within the given {\fg}. \subsection{ Determine Test Cases} From the failure modes associated with the functional~group, -we now need to determine test cases. +test cases must next be determined. +%we now need to determine test cases. +% The test cases are collections of failure modes. These can be formed from single failure modes or failure modes in combination. Let $\mathcal{TC}$ be the set of all test cases, $\mathcal{F}$ be the set of all failure modes. %(associated with the functional group $FG$). -We define the function $dtc$ thus: +The function $dtc$ is defined thus: % $$ dtc: \mathcal{F} \rightarrow \mathcal{TC}, $$ % @@ -507,7 +509,7 @@ Ideally field data and/or formal physical testing should be used in addition to where possible. % When all the test cases have been analysed, -we will have a `result' for each `test case'. +a `result' will exist for each `test case'. % Each result will be described from the perspective of %{\wrt} to the {\fg}, not the members of it i.e. the components. % failure modes. @@ -519,8 +521,10 @@ the {\fg}, not the members of it i.e. the components. % failure modes. %% % -Thus we will have a set of -results corresponding to our test cases. These share a common index value ($j$ in the algorithm description). +A set of +results corresponding to our test cases is now available. +% +These share a common index value ($j$ in the algorithm description). These results are the failure modes of the {\fg}. \fmmdgloss %Once a functional group has been analysed, it can be re-used in @@ -546,7 +550,7 @@ has the same failure symptom. Let set $\mathcal{SP}$ be the set of all symptoms, and $\mathcal{R}$ be the set of all test case results. % -We define the function $fcs$ thus: +The function $fcs$ is defined thus: % $$fcs: \mathcal{R} \rightarrow \mathcal{SP} ,$$ given by @@ -602,7 +606,7 @@ $$ fcs(R) = SP .$$ This raises the failure~mode abstraction level, $\abslev$ (see section~\ref{sec:alpha}). The failures have now been considered not from the component level, but from the sub-system or functional~group level. -We now have a set $SP$ of the symptoms of failure. +A set $SP$, the symptoms of failure is obtained. % \ifthenelse {\boolean{paper}} { @@ -638,7 +642,7 @@ This final stage is the creation of the derived component. This derived component may now be used to build new {\fgs} at higher levels of fault abstraction. Let $DC$ be a derived component with its own set of failure~modes. -We define the function $cdc$ thus: +The function $cdc$ is defined thus: $$ cdc: \mathcal{SP} \rightarrow \mathcal{DC} , $$ % given by @@ -670,19 +674,23 @@ The new component will have a set of failure modes that correspond to the common % %Algorithm \ref{alg55} %The function $cdc$ is the final stage in the process. -We now have a -derived~component $DC$, which has its own set of failure~modes. This can now be +A +derived~component $DC$, which has its own set of failure~modes has been created. +% +This can now be used in with other components (or derived~components) to form functional~groups at higher levels of failure~mode~abstraction. %Hierarchies of fault abstraction can be built that can model an entire SYSTEM. \paragraph{Enumerating abstraction levels.} \label{sec:abstractionlevel} -As described in section~\ref{sec:alpha} we can assign the attribute of abstraction level $\abslev$ to +% +As described in section~\ref{sec:alpha} the attribute of abstraction level $\abslev$ can be assigned to components, where $\abslev$ is a natural number, ($\abslev \in \mathbb{N}_0$). +% For a base component, let the abstraction level be zero. % -If we apply the symptom abstraction process $\derivec$, -the resulting derived~component will have an $\abslev$ value +The symptom abstraction process is applied giving a $\derivec$, +this derived~component will have an $\abslev$ value one higher than the highest $\abslev$ value of any of the components in the {\fg} used to derive it. % @@ -725,7 +733,8 @@ as is found in practise in real world systems. Since the fault modes are determined from the bottom-up, the causes for all high level faults naturally form trees. % -That is to say from the bottom-up causes become symptoms, which in the next level become causes as we traverse up the tree. +That is to say from the bottom-up causes become symptoms, +which in the next level become causes as the tree is traversed upwards. % This is demonstrated in the examples chapter~\ref{sec:chap5} where DAGS are drawn linking failure mode causes and symptoms in FMMD analysis hierarchies.